Dosimetric implications of inter- and intrafractional prostate positioning errors during tomotherapy : Comparison of gold marker-based registrations with native MVCT.

Science.gov (United States)

Wust, Peter; Joswig, Marc; Graf, Reinhold; Böhmer, Dirk; Beck, Marcus; Barelkowski, Thomasz; Budach, Volker; Ghadjar, Pirus

2017-09-01

For high-dose radiation therapy (RT) of prostate cancer, image-guided (IGRT) and intensity-modulated RT (IMRT) approaches are standard. Less is known regarding comparisons of different IGRT techniques and the resulting residual errors, as well as regarding their influences on dose distributions. A total of 58 patients who received tomotherapy-based RT up to 84 Gy for high-risk prostate cancer underwent IGRT based either on daily megavoltage CT (MVCT) alone (n = 43) or the additional use of gold markers (n = 15) under routine conditions. Planned Adaptive (Accuray Inc., Madison, WI, USA) software was used for elaborated offline analysis to quantify residual interfractional prostate positioning errors, along with systematic and random errors and the resulting safety margins after both IGRT approaches. Dosimetric parameters for clinical target volume (CTV) coverage and exposition of organs at risk (OAR) were also analyzed and compared. Interfractional as well as intrafractional displacements were determined. Particularly in the vertical direction, residual interfractional positioning errors were reduced using the gold marker-based approach, but dosimetric differences were moderate and the clinical relevance relatively small. Intrafractional prostate motion proved to be quite high, with displacements of 1-3 mm; however, these did not result in additional dosimetric impairments. Residual interfractional positioning errors were reduced using gold marker-based IGRT; however, this resulted in only slightly different final dose distributions. Therefore, daily MVCT-based IGRT without markers might be a valid alternative.

Dosimetric comparison of IMRT and modulated arc-therapy techniques in the treatment of cervical cancers; Comparaison dosimetrique des techniques de RCMI et d'arctherapie modulee dans le traitement des cancers du col uterin

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Renard-Oldrini, S.; Charra-Brunaud, C.; Tournier-Rangeard, L.; Huger, S.; Marchesi, V.; Bouziz, D.; Peiffert, D. [Centre Alexis-Vautrin, Nancy (France)

2011-10-15

The authors report the dosimetric comparison of two techniques used for the treatment of cervical cancers: the intensity-modulated conformational radiotherapy (IMRT) with static beams and modulated arc-therapy with RapidArc. The treatment plans of 15 patients have been compared. The clinical target volume (CTV) comprises the gross target volume, the cervix, the upper third of the vagina, and ganglionary areas. The previsional target volume comprises the clinical target volume and a one centimetre margin. Organs at risk are rectum, bladder, intestine and bone marrow. Arc-therapy seems to provide a better sparing of intestine that IMRT, while maintaining a good coverage of the previsional target volume and decreasing treatment duration. Short communication

Evaluating the dosimetric effect of treatment-induced changes in virally mediated head and neck cancer patients

International Nuclear Information System (INIS)

Brown, Elizabeth; Owen, Rebecca; Mengersen, Kerrie; Harden, Fiona; Porceddu, Sandro

2013-01-01

Patients with virally mediated head and neck cancer (VMHNC) often present with advanced nodal disease that is highly radioresponsive as demonstrated by tumour and nodal regression during treatment. The resultant changes may impact on the planned dose distribution and so adversely affect the therapeutic ratio. The aim of this study was to evaluate the dosimetric effect of treatment-induced anatomical changes in VMHNC patients who had undergone a replan. Thirteen patients with virally mediated oropharyngeal or nasopharyngeal cancer who presented for definitive radiotherapy between 2005 and 2010 and who had a replan generated were investigated. The dosimetric effect of anatomical changes was quantified by comparing dose–volume histograms (DVH) of primary and nodal gross target volumes and organs at risk (OAR), including spinal cord and parotid glands, from the original plan and a comparison plan. Eleven three-dimensional conformal radiation therapy (3DCRT) and two intensity modulated radiation therapy (IMRT) plans were evaluated. Dose to the spinal cord and brainstem increased by 4.1% and 2.6%, respectively. Mean dose to the parotid glands also increased by 3.5%. In contrast, the dose received by 98% of the primary and nodal gross tumour volumes decreased by 0.15% and 0.3%, respectively, when comparing the initial treatment plan to the comparison plan. In this study, treatment-induced anatomical changes had the greatest impact on OAR dose with negligible effect on the dose to nodal gross tumour volumes. In the era of IMRT, accounting for treatment-induced anatomical changes is important as focus is placed on minimizing the acute and long-term side effects of treatment

A comparison of the quality assurance of four dosimetric tools for intensity modulated radiation therapy

International Nuclear Information System (INIS)

Son, Jaeman; Baek, Taesung; Lee, Boram; Shin, Dongho; Park, Sung Yong; Park, Jeonghoon; Lim, Young Kyung; Lee, Se Byeong; Kim, Jooyoung; Yoon, Myonggeun

2015-01-01

This study was designed to compare the quality assurance (QA) results of four dosimetric tools used for intensity modulated radiation therapy (IMRT) and to suggest universal criteria for the passing rate in QA, irrespective of the dosimetric tool used. Thirty fields of IMRT plans from five patients were selected, followed by irradiation onto radiochromic film, a diode array (Mapcheck), an ion chamber array (MatriXX) and an electronic portal imaging device (EPID) for patient-specific QA. The measured doses from the four dosimetric tools were compared with the dose calculated by the treatment planning system. The passing rates of the four dosimetric tools were calculated using the gamma index method, using as criteria a dose difference of 3% and a distance-to-agreement of 3 mm. The QA results based on Mapcheck, MatriXX and EPID showed good agreement, with average passing rates of 99.61%, 99.04% and 99.29%, respectively. However, the average passing rate based on film measurement was significantly lower, 95.88%. The average uncertainty (1 standard deviation) of passing rates for 6 intensity modulated fields was around 0.31 for film measurement, larger than those of the other three dosimetric tools. QA results and consistencies depend on the choice of dosimetric tool. Universal passing rates should depend on the normalization or inter-comparisons of dosimetric tools if more than one dosimetric tool is used for patient specific QA

A comparison of the quality assurance of four dosimetric tools for intensity modulated radiation therapy.

Science.gov (United States)

Son, Jaeman; Baek, Taesung; Lee, Boram; Shin, Dongho; Park, Sung Yong; Park, Jeonghoon; Lim, Young Kyung; Lee, Se Byeong; Kim, Jooyoung; Yoon, Myonggeun

2015-09-01

This study was designed to compare the quality assurance (QA) results of four dosimetric tools used for intensity modulated radiation therapy (IMRT) and to suggest universal criteria for the passing rate in QA, irrespective of the dosimetric tool used. Thirty fields of IMRT plans from five patients were selected, followed by irradiation onto radiochromic film, a diode array (Mapcheck), an ion chamber array (MatriXX) and an electronic portal imaging device (EPID) for patient-specific QA. The measured doses from the four dosimetric tools were compared with the dose calculated by the treatment planning system. The passing rates of the four dosimetric tools were calculated using the gamma index method, using as criteria a dose difference of 3% and a distance-to-agreement of 3 mm. The QA results based on Mapcheck, MatriXX and EPID showed good agreement, with average passing rates of 99.61%, 99.04% and 99.29%, respectively. However, the average passing rate based on film measurement was significantly lower, 95.88%. The average uncertainty (1 standard deviation) of passing rates for 6 intensity modulated fields was around 0.31 for film measurement, larger than those of the other three dosimetric tools. QA results and consistencies depend on the choice of dosimetric tool. Universal passing rates should depend on the normalization or inter-comparisons of dosimetric tools if more than one dosimetric tool is used for patient specific QA.

A dosimetric comparison of 3D conformal vs intensity modulated vs volumetric arc radiation therapy for muscle invasive bladder cancer

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Foroudi Farshad

2012-07-01

Full Text Available Abstract Background To compare 3 Dimensional Conformal radiotherapy (3D-CRT with Intensity Modulated Radiotherapy (IMRT with Volumetric-Modulated Arc Therapy (VMAT for bladder cancer. Methods Radiotherapy plans for 15 patients with T2-T4N0M0 bladder cancer were prospectively developed for 3-DCRT, IMRT and VMAT using Varian Eclipse planning system. The same radiation therapist carried out all planning and the same clinical dosimetric constraints were used. 10 of the patients with well localised tumours had a simultaneous infield boost (SIB of the primary tumour planned for both IMRT and VMAT. Tumour control probabilities and normal tissue complication probabilities were calculated. Results Mean planning time for 3D-CRT, IMRT and VMAT was 30.0, 49.3, and 141.0 minutes respectively. The mean PTV conformity (CI index for 3D-CRT was 1.32, for IMRT 1.05, and for VMAT 1.05. The PTV Homogeneity (HI index was 0.080 for 3D-CRT, 0.073 for IMRT and 0.086 for VMAT. Tumour control and normal tissue complication probabilities were similar for 3D-CRT, IMRT and VMAT. The mean monitor units were 267 (range 250–293 for 3D-CRT; 824 (range 641–1083 for IMRT; and 403 (range 333–489 for VMAT (P  Conclusions VMAT is associated with similar dosimetric advantages as IMRT over 3D-CRT for muscle invasive bladder cancer. VMAT is associated with faster delivery times and less number of mean monitor units than IMRT. SIB is feasible in selected patients with localized tumours.

Individualized margins in 3D conformal radiotherapy planning for lung cancer: analysis of physiological movements and their dosimetric impacts.

Science.gov (United States)

Germain, François; Beaulieu, Luc; Fortin, André

2008-01-01

In conformal radiotherapy planning for lung cancer, respiratory movements are not taken into account when a single computed tomography (CT) scan is performed. This study examines tumor movements to design individualized margins to account for these movements and evaluates their dosimetric impacts on planning volume. Fifteen patients undergoing CT-based planning for radical radiotherapy for localized lung cancer formed the study cohort. A reference plan was constructed based on reference gross, clinical, and planning target volumes (rGTV, rCTV, and rPTV, respectively). The reference plans were compared with individualized plans using individualized margins obtained by using 5 serial CT scans to generate individualized target volumes (iGTV, iCTV, and iPTV). Three-dimensional conformal radiation therapy was used for plan generation using 6- and 23-MV photon beams. Ten plans for each patient were generated and dose-volume histograms (DVHs) were calculated. Comparisons of volumetric and dosimetric parameters were performed using paired Student t-tests. Relative to the rGTV, the total volume occupied by the superimposed GTVs increased progressively with each additional CT scans. With the use of all 5 scans, the average increase in GTV was 52.1%. For the plans with closest dosimetric coverage, target volume was smaller (iPTV/rPTV ratio 0.808) but lung irradiation was only slightly decreased. Reduction in the proportion of lung tissue that received 20 Gy or more outside the PTV (V20) was observed both for 6-MV plans (-0.73%) and 23-MV plans (-0.65%), with p = 0.02 and p = 0.04, respectively. In conformal RT planning for the treatment of lung cancer, the use of serial CT scans to evaluate respiratory motion and to generate individualized margins to account for these motions produced only a limited lung sparing advantage.

Individualized Margins in 3D Conformal Radiotherapy Planning for Lung Cancer: Analysis of Physiological Movements and Their Dosimetric Impacts

International Nuclear Information System (INIS)

Germain, Francois; Beaulieu, Luc; Fortin, Andre

2008-01-01

In conformal radiotherapy planning for lung cancer, respiratory movements are not taken into account when a single computed tomography (CT) scan is performed. This study examines tumor movements to design individualized margins to account for these movements and evaluates their dosimetric impacts on planning volume. Fifteen patients undergoing CT-based planning for radical radiotherapy for localized lung cancer formed the study cohort. A reference plan was constructed based on reference gross, clinical, and planning target volumes (rGTV, rCTV, and rPTV, respectively). The reference plans were compared with individualized plans using individualized margins obtained by using 5 serial CT scans to generate individualized target volumes (iGTV, iCTV, and iPTV). Three-dimensional conformal radiation therapy was used for plan generation using 6- and 23-MV photon beams. Ten plans for each patient were generated and dose-volume histograms (DVHs) were calculated. Comparisons of volumetric and dosimetric parameters were performed using paired Student t-tests. Relative to the rGTV, the total volume occupied by the superimposed GTVs increased progressively with each additional CT scans. With the use of all 5 scans, the average increase in GTV was 52.1%. For the plans with closest dosimetric coverage, target volume was smaller (iPTV/rPTV ratio 0.808) but lung irradiation was only slightly decreased. Reduction in the proportion of lung tissue that received 20 Gy or more outside the PTV (V20) was observed both for 6-MV plans (-0.73%) and 23-MV plans (-0.65%), with p = 0.02 and p = 0.04, respectively. In conformal RT planning for the treatment of lung cancer, the use of serial CT scans to evaluate respiratory motion and to generate individualized margins to account for these motions produced only a limited lung sparing advantage

Dosimetric Comparison in Breast Radiotherapy of 4 MV and 6 MV on Physical Chest Simulator

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Donato da Silva, Sabrina; Passos Ribeiro Campos, Tarcisio [Nuclear Engineering Department, Federal University of Minas Gerais, Belo Horizonte (Brazil); Batista Nogueira, Luciana [Anatomy and Imaging Department, Federal University of Minas Gerais, Belo Horizonte (Brazil); Lima Souza Castro, Andre [Nuclear Engineering Department, Federal University of Minas Gerais, Belo Horizonte (Brazil); Institute of Radiation San Francisco, Belo Horizonte (Brazil); Alves de oliveira, Marcio; Galvao Dias, Humberto [Cancer Hospital in Uberlandia, Uberlandia (Brazil)

2015-07-01

According to the World Health Organization (2014) breast cancer is the main cause of death by cancer in women worldwide. The biggest challenge of radiotherapy in the treatment of cancer is to deposit the entire prescribed dose homogeneously in the breast, sparing the surrounding tissue. In this context, this paper aimed at evaluating and comparing internal dose distribution in the mammary gland based on experimental procedures submitted to two distinct energy spectra produced in breast cancer radiotherapy. The methodology consisted of reproducing opposite parallel fields used in the treatment of breast tumors in a chest phantom. This simulator with synthetic breast, composed of equivalent tissue material (TE), was previously developed by the NRI Research Group (UFMG). The computer tomography (CT) scan of the simulator was obtained antecedently. The radiotherapy planning systems (TPS) in the chest phantom were performed in the ECLIPSE system from Varian Medical Systems and CAT 3D system from MEVIS. The irradiations were reproduced in the Varian linear accelerator, model SL- 20 Precise, 6 MV energy and Varian linear accelerator, 4 MV Clinac 6x SN11 model. Calibrations of the absorbed dose versus optical density from radiochromic films were generated in order to obtain experimental dosimetric distribution at the films positioned within the glandular and skin equivalent tissues of the chest phantom. The spatial dose distribution showed equivalence with the TPS on measurement data performed in the 6 MV spectrum. The average dose found in radiochromic films placed on the skin ranged from 49 to 79%, and from 39 to 49% in the mammary areola, for the prescribed dose. Dosimetric comparisons between the spectra of 4 and 6 MV, keeping the constant geometry of the fields applied in the same phantom, will be presented showing their equivalence in breast radiotherapy, as well as the variations will be discussed. To sum up, the dose distribution has reached the value expected in

Dosimetric Feasibility of Hypofractionated Proton Radiotherapy for Neoadjuvant Pancreatic Cancer Treatment

International Nuclear Information System (INIS)

Kozak, Kevin R.; Kachnic, Lisa A.; Adams, Judith C; Crowley, Elizabeth M.; Alexander, Brian M.; Mamon, Harvey J.; Fernandez-Del Castillo, Carlos; Ryan, David P.; DeLaney, Thomas F.; Hong, Theodore S.

2007-01-01

Purpose: To evaluate tumor and normal tissue dosimetry of a 5 cobalt gray equivalent (CGE) x 5 fraction proton radiotherapy schedule, before initiating a clinical trial of neoadjuvant, short-course proton radiotherapy for pancreatic adenocarcinoma. Methods and Materials: The first 9 pancreatic cancer patients treated with neoadjuvant intensity-modulated radiotherapy (1.8 Gy x 28) at the Massachusetts General Hospital had treatment plans generated using a 5 CGE x 5 fraction proton regimen. To facilitate dosimetric comparisons, clinical target volumes and normal tissue volumes were held constant. Plans were optimized for target volume coverage and normal tissue sparing. Results: Hypofractionated proton and conventionally fractionated intensity-modulated radiotherapy plans both provided acceptable target volume coverage and dose homogeneity. Improved dose conformality provided by the hypofractionated proton regimen resulted in significant sparing of kidneys, liver, and small bowel, evidenced by significant reductions in the mean doses, expressed as percentage prescribed dose, to these structures. Kidney and liver sparing was most evident in low-dose regions (≤20% prescribed dose for both kidneys and ≤60% prescribed dose for liver). Improvements in small-bowel dosimetry were observed in high- and low-dose regions. Mean stomach and duodenum doses, expressed as percentage prescribed dose, were similar for the two techniques. Conclusions: A proton radiotherapy schedule consisting of 5 fractions of 5 CGE as part of neoadjuvant therapy for adenocarcinoma of the pancreas seems dosimetrically feasible, providing excellent target volume coverage, dose homogeneity, and normal tissue sparing. Hypofractionated proton radiotherapy in this setting merits Phase I clinical trial investigation

Postoperative Intensity Modulated Radiation Therapy in High Risk Prostate Cancer: A Dosimetric Comparison

International Nuclear Information System (INIS)

Digesu, Cinzia; Cilla, Savino; De Gaetano, Andrea; Massaccesi, Mariangela; Macchia, Gabriella; Ippolito, Edy; Deodato, Francesco; Panunzi, Simona; Iapalucci, Chiara; Mattiucci, Gian Carlo; D'Angelo, Elisa; Padula, Gilbert D.A.; Valentini, Vincenzo; Cellini, Numa

2011-01-01

The aim of this study was to compare intensity-modulated radiation therapy (IMRT) with 3D conformal technique (3D-CRT), with respect to target coverage and irradiation of organs at risk for high dose postoperative radiotherapy (PORT) of the prostate fossa. 3D-CRT and IMRT treatment plans were compared with respect to dose to the rectum and bladder. The dosimetric comparison was carried out in 15 patients considering 2 different scenarios: (1) exclusive prostate fossa irradiation, and (2) pelvic node irradiation followed by a boost on the prostate fossa. In scenario (1), a 3D-CRT plan (box technique) and an IMRT plan were calculated and compared for each patient. In scenario (2), 3 treatment plans were calculated and compared for each patient: (a) 3D-CRT box technique for both pelvic (prophylactic nodal irradiation) and prostate fossa irradiation (3D-CRT only); (b) 3D-CRT box technique for pelvic irradiation followed by an IMRT boost to the prostatic fossa (hybrid 3D-CRT and IMRT); and (c) IMRT for both pelvic and prostate fossa irradiation (IMRT only). For exclusive prostate fossa irradiation, IMRT significantly reduced the dose to the rectum (lower Dmean, V50%, V75%, V90%, V100%, EUD, and NTCP) and the bladder (lower Dmean, V50%, V90%, EUD and NTCP). When prophylactic irradiation of the pelvis was also considered, plan C (IMRT only) performed better than plan B (hybrid 3D-CRT and IMRT) as respect to both rectum and bladder irradiation (reduction of Dmean, V50%, V75%, V90%, equivalent uniform dose [EUD], and normal tissue complication probability [NTCP]). Plan (b) (hybrid 3D-CRT and IMRT) performed better than plan (a) (3D-CRT only) with respect to dose to the rectum (lower Dmean, V75%, V90%, V100%, EUD, and NTCP) and the bladder (Dmean, EUD, and NTCP). Postoperative IMRT in prostate cancer significantly reduces rectum and bladder irradiation compared with 3D-CRT.

Patient feature based dosimetric Pareto front prediction in esophageal cancer radiotherapy.

Science.gov (United States)

Wang, Jiazhou; Jin, Xiance; Zhao, Kuaike; Peng, Jiayuan; Xie, Jiang; Chen, Junchao; Zhang, Zhen; Studenski, Matthew; Hu, Weigang

2015-02-01

To investigate the feasibility of the dosimetric Pareto front (PF) prediction based on patient's anatomic and dosimetric parameters for esophageal cancer patients. Eighty esophagus patients in the authors' institution were enrolled in this study. A total of 2928 intensity-modulated radiotherapy plans were obtained and used to generate PF for each patient. On average, each patient had 36.6 plans. The anatomic and dosimetric features were extracted from these plans. The mean lung dose (MLD), mean heart dose (MHD), spinal cord max dose, and PTV homogeneity index were recorded for each plan. Principal component analysis was used to extract overlap volume histogram (OVH) features between PTV and other organs at risk. The full dataset was separated into two parts; a training dataset and a validation dataset. The prediction outcomes were the MHD and MLD. The spearman's rank correlation coefficient was used to evaluate the correlation between the anatomical features and dosimetric features. The stepwise multiple regression method was used to fit the PF. The cross validation method was used to evaluate the model. With 1000 repetitions, the mean prediction error of the MHD was 469 cGy. The most correlated factor was the first principal components of the OVH between heart and PTV and the overlap between heart and PTV in Z-axis. The mean prediction error of the MLD was 284 cGy. The most correlated factors were the first principal components of the OVH between heart and PTV and the overlap between lung and PTV in Z-axis. It is feasible to use patients' anatomic and dosimetric features to generate a predicted Pareto front. Additional samples and further studies are required improve the prediction model.

A Dosimetric Comparison of Tomotherapy and Volumetric Modulated Arc Therapy in the Treatment of High-Risk Prostate Cancer With Pelvic Nodal Radiation Therapy

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Pasquier, David, E-mail: d-pasquier@o-lambret.fr [Departement Universitaire de Radiotherapie, Centre O. Lambret, Lille (France); Universite Lille Nord de France, Lille (France); Centre Galilee, Clinique de la Louviere, Lille (France); Cavillon, Fabrice [Universite Lille Nord de France, Lille (France); Faculte Libre de Medecine, Lille (France); Lacornerie, Thomas [Departement Universitaire de Radiotherapie, Centre O. Lambret, Lille (France); Universite Lille Nord de France, Lille (France); Touzeau, Claire [Centre Galilee, Clinique de la Louviere, Lille (France); Tresch, Emmanuelle [Unite de Methodologie et Biostatistique, Centre O. Lambret, Lille (France); Lartigau, Eric [Departement Universitaire de Radiotherapie, Centre O. Lambret, Lille (France); Universite Lille Nord de France, Lille (France)

2013-02-01

Purpose: To compare the dosimetric results of volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) in the treatment of high-risk prostate cancer with pelvic nodal radiation therapy. Methods and Materials: Plans were generated for 10 consecutive patients treated for high-risk prostate cancer with prophylactic whole pelvic radiation therapy (WPRT) using VMAT and HT. After WPRT, a sequential boost was delivered to the prostate. Plan quality was assessed according to the criteria of the International Commission on Radiation Units and Measurements 83 report: the near-minimal (D98%), near-maximal (D2%), and median (D50%) doses; the homogeneity index (HI); and the Dice similarity coefficient (DSC). Beam-on time, integral dose, and several organs at risk (OAR) dosimetric indexes were also compared. Results: For WPRT, HT was able to provide a higher D98% than VMAT (44.3 {+-} 0.3 Gy and 43.9 {+-} 0.5 Gy, respectively; P=.032) and a lower D2% than VMAT (47.3 {+-} 0.3 Gy and 49.1 {+-} 0.7 Gy, respectively; P=.005), leading to a better HI. The DSC was better for WPRT with HT (0.89 {+-} 0.009) than with VMAT (0.80 {+-} 0.02; P=.002). The dosimetric indexes for the prostate boost did not differ significantly. VMAT provided better rectum wall sparing at higher doses (V70, V75, D2%). Conversely, HT provided better bladder wall sparing (V50, V60, V70), except at lower doses (V20). The beam-on times for WPRT and prostate boost were shorter with VMAT than with HT (3.1 {+-} 0.1 vs 7.4 {+-} 0.6 min, respectively; P=.002, and 1.5 {+-} 0.05 vs 3.7 {+-} 0.3 min, respectively; P=.002). The integral dose was slightly lower for VMAT. Conclusion: VMAT and HT provided very similar and highly conformal plans that complied well with OAR dose-volume constraints. Although some dosimetric differences were statistically significant, they remained small. HT provided a more homogeneous dose distribution, whereas VMAT enabled a shorter delivery time.

A dosimetric comparison of two-phase adaptive intensity-modulated radiotherapy for locally advanced nasopharyngeal cancer

International Nuclear Information System (INIS)

Chitapanarux, Imjai; Chomprasert, Kittisak; Nobnaop, Wannapa; Wanwilairat, Somsak; Tharavichitkul, Ekasit; Jakrabhandu, Somvilai; Onchan, Wimrak; Patrinee, Traisathit; Gestel, Dirk Van

2015-01-01

The purpose of this investigation was to evaluate the potential dosimetric benefits of a two-phase adaptive intensity-modulated radiotherapy (IMRT) protocol for patients with locally advanced nasopharyngeal cancer (NPC). A total of 17 patients with locally advanced NPC treated with IMRT had a second computed tomography (CT) scan after 17 fractions in order to apply and continue the treatment with an adapted plan after 20 fractions. To simulate the situation without adaptation, a hybrid plan was generated by applying the optimization parameters of the original treatment plan to the anatomy of the second CT scan. The dose-volume histograms (DVHs) and dose statistics of the hybrid plan and the adapted plan were compared. The mean volume of the ipsilateral and contralateral parotid gland decreased by 6.1 cm 3 (30.5%) and 5.4 cm 3 (24.3%), respectively. Compared with the hybrid plan, the adapted plan provided a higher dose to the target volumes with better homogeneity, and a lower dose to the organs at risk (OARs). The Dmin of all planning target volumes (PTVs) increased. The Dmax of the spinal cord and brainstem were lower in 94% of the patients (1.6-5.9 Gy, P < 0.001 and 2.1-9.9 Gy, P < 0.001, respectively). The D mean of the contralateral parotid decreased in 70% of the patients (range, 0.2-4.4 Gy). We could not find a relationship between dose variability and weight loss. Our two-phase adaptive IMRT protocol improves dosimetric results in terms of target volumes and OARs in patients with locally advanced NPC. (author)

Dosimetric comparison of flattened and unflattened beams for stereotactic ablative radiotherapy of stage I non-small cell lung cancer

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Hrbacek, Jan, E-mail: jan.hrbacek@psi.ch [Klinik für Radio-Onkologie, UniversitätsSpital Zürich, 8091 Zürich, Switzerland and Center for Proton Therapy, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Lang, Stephanie; Graydon, Shaun N.; Klöck, Stephan; Riesterer, Oliver [Klinik für Radio-Onkologie, UniversitätsSpital Zürich, 8091 Zürich (Switzerland)

2014-03-15

Purpose: To compare contribution and accuracy of delivery for two flattening filter free (FFF) beams of the nominal energy 6 and 10 MV and a 6 MV flattened beam for early stage lung cancer. Methods: For each of 11 patients with stage I nonsmall cell lung cancer three volumetric modulated arc therapy plans were prepared utilizing a 6 MV flattened photon beam (X6FF) and two nonflattened beams of nominal energy 6 and 10 MV (X6FFF, X10FFF). Optimization constraints were set to produce dose distributions that meet the criteria of the RTOG-0915 protocol. The radiation schedule used for plan comparison in all patients was 50 Gy in five fractions. Dosimetric parameters of planning target volume (PTV) and organs-at-risk and delivery times were assessed and compared. All plans were subject to verification using Delta{sup 4} unit (Scandidos, Sweden) and absolutely calibrated gafchromic films in a thorax phantom. Results: All plans had a qualitatively comparable outcome. Obtained dose distributions were conformal (CI < 1.17) and exhibited a steep dose fall-off outside the PTV. The ratio of monitor units for FFF versus FF plans in the authors' study ranged from 0.95 to 1.21 and from 0.93 to 1.25 for X6FFF/X6FF and X10FFF/X6FF comparisons, respectively. The ratio systematically increased with increasing size of the PTV (up to +25% for 150 cm{sup 3} PTV). Yet the integral dose to healthy tissue did not follow this trend. Comparison of cumulative dose volume histograms for a patient's body showed that X6FFF plans exhibit improved conformity and reduced the volume of tissue that received more than 50% of the prescription dose. Parameters related to dose gradient showed statistically significant improvement. CI{sub 50%}, CI{sub 60%}, CI{sub 80%}, and CI{sub 100%} were on average reduced by 4.6% (p < 0.001), 4.6% (p = 0.002), 3.1% (p = 0.002), and 1.2% (p = 0.039), respectively. Gradient measure was on average reduced by 4.2% (p < 0.001). Due to dose reduction in the

A Dosimetric Comparison of Tomotherapy and Volumetric Modulated Arc Therapy in the Treatment of High-Risk Prostate Cancer With Pelvic Nodal Radiation Therapy

International Nuclear Information System (INIS)

Pasquier, David; Cavillon, Fabrice; Lacornerie, Thomas; Touzeau, Claire; Tresch, Emmanuelle; Lartigau, Eric

2013-01-01

Purpose: To compare the dosimetric results of volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) in the treatment of high-risk prostate cancer with pelvic nodal radiation therapy. Methods and Materials: Plans were generated for 10 consecutive patients treated for high-risk prostate cancer with prophylactic whole pelvic radiation therapy (WPRT) using VMAT and HT. After WPRT, a sequential boost was delivered to the prostate. Plan quality was assessed according to the criteria of the International Commission on Radiation Units and Measurements 83 report: the near-minimal (D98%), near-maximal (D2%), and median (D50%) doses; the homogeneity index (HI); and the Dice similarity coefficient (DSC). Beam-on time, integral dose, and several organs at risk (OAR) dosimetric indexes were also compared. Results: For WPRT, HT was able to provide a higher D98% than VMAT (44.3 ± 0.3 Gy and 43.9 ± 0.5 Gy, respectively; P=.032) and a lower D2% than VMAT (47.3 ± 0.3 Gy and 49.1 ± 0.7 Gy, respectively; P=.005), leading to a better HI. The DSC was better for WPRT with HT (0.89 ± 0.009) than with VMAT (0.80 ± 0.02; P=.002). The dosimetric indexes for the prostate boost did not differ significantly. VMAT provided better rectum wall sparing at higher doses (V70, V75, D2%). Conversely, HT provided better bladder wall sparing (V50, V60, V70), except at lower doses (V20). The beam-on times for WPRT and prostate boost were shorter with VMAT than with HT (3.1 ± 0.1 vs 7.4 ± 0.6 min, respectively; P=.002, and 1.5 ± 0.05 vs 3.7 ± 0.3 min, respectively; P=.002). The integral dose was slightly lower for VMAT. Conclusion: VMAT and HT provided very similar and highly conformal plans that complied well with OAR dose-volume constraints. Although some dosimetric differences were statistically significant, they remained small. HT provided a more homogeneous dose distribution, whereas VMAT enabled a shorter delivery time.

A dosimetric comparison of tomotherapy and volumetric modulated arc therapy in the treatment of high-risk prostate cancer with pelvic nodal radiation therapy.

Science.gov (United States)

Pasquier, David; Cavillon, Fabrice; Lacornerie, Thomas; Touzeau, Claire; Tresch, Emmanuelle; Lartigau, Eric

2013-02-01

To compare the dosimetric results of volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) in the treatment of high-risk prostate cancer with pelvic nodal radiation therapy. Plans were generated for 10 consecutive patients treated for high-risk prostate cancer with prophylactic whole pelvic radiation therapy (WPRT) using VMAT and HT. After WPRT, a sequential boost was delivered to the prostate. Plan quality was assessed according to the criteria of the International Commission on Radiation Units and Measurements 83 report: the near-minimal (D98%), near-maximal (D2%), and median (D50%) doses; the homogeneity index (HI); and the Dice similarity coefficient (DSC). Beam-on time, integral dose, and several organs at risk (OAR) dosimetric indexes were also compared. For WPRT, HT was able to provide a higher D98% than VMAT (44.3 ± 0.3 Gy and 43.9 ± 0.5 Gy, respectively; P=.032) and a lower D2% than VMAT (47.3 ± 0.3 Gy and 49.1 ± 0.7 Gy, respectively; P=.005), leading to a better HI. The DSC was better for WPRT with HT (0.89 ± 0.009) than with VMAT (0.80 ± 0.02; P=.002). The dosimetric indexes for the prostate boost did not differ significantly. VMAT provided better rectum wall sparing at higher doses (V70, V75, D2%). Conversely, HT provided better bladder wall sparing (V50, V60, V70), except at lower doses (V20). The beam-on times for WPRT and prostate boost were shorter with VMAT than with HT (3.1 ± 0.1 vs 7.4 ± 0.6 min, respectively; P=.002, and 1.5 ± 0.05 vs 3.7 ± 0.3 min, respectively; P=.002). The integral dose was slightly lower for VMAT. VMAT and HT provided very similar and highly conformal plans that complied well with OAR dose-volume constraints. Although some dosimetric differences were statistically significant, they remained small. HT provided a more homogeneous dose distribution, whereas VMAT enabled a shorter delivery time. Copyright © 2013 Elsevier Inc. All rights reserved.

Dosimetric planning study for the prevention of anal complications after post-operative whole pelvic radiotherapy in cervical cancer patients with hemorrhoids.

Science.gov (United States)

Baek, J G; Kim, E C; Kim, S K; Jang, H

2015-01-01

Radiation-induced anal toxicity can be induced by low radiation doses in patients with haemorrhoids. The object of this study was to determine the dosimetric benefits of different whole pelvic radiotherapy (WPRT) techniques in terms of dose delivered to the anal canal in post-operative patients with cervical cancer. The planning CT images of 10 patients with cervical cancer undergoing postoperative radiotherapy were used for comparison of three different plans. All patients had been treated using the conventional box technique WPRT (CV-WPRT), and we tried low-margin-modified WPRT (LM-WPRT), three-dimensional conformal techniques WPRT (CF-WPRT) and intensity-modulated WPRT (IM-WPRT) planning for dosimetric comparison of the anal canal, retrospectively. Mean anal canal doses of the IM-WPRT were significantly lower (p 99%, and the proportion that received ≥108% of the prescribed dose for IM-WPRT was <2%. Volumes of bladders and rectums that received ≥30 or ≥40 Gy were significantly lower for IM-WPRT than for three of the four-field WPRT plans (p = 0.000). IM-WPRT can significantly reduce radiation dose delivered to the anal canal and does not compromise PTV coverage. In patients with haemorrhoids, IM-WPRT may be of value for the prevention of anal complications. Although tolerance of the anal canal tends to be ignored in patients undergoing post-operative WPRT, patients with haemorrhoids may suffer complications at low radiation doses. The present study shows IM-WPRT can be meaningful in these patients.

Dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer

International Nuclear Information System (INIS)

Yang, Yun; Catalano, Suzanne; Kelsey, Chris R.; Yoo, David S.; Yin, Fang-Fang; Cai, Jing

2014-01-01

To quantitatively evaluate dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer. Overall, 11 lung SBRT patients (8 female and 3 male; mean age: 75.0 years) with medially located tumors were included. Treatment plans with simulated rotational offsets of 1°, 3°, and 5° in roll, yaw, and pitch were generated and compared with the original plans. Both clockwise and counterclockwise rotations were investigated. The following dosimetric metrics were quantitatively evaluated: planning target volume coverage (PTV V 100% ), max PTV dose (PTV D max ), percentage prescription dose to 0.35 cc of cord (cord D 0.35 cc ), percentage prescription dose to 0.35 cc and 5 cc of esophagus (esophagus D 0.35 cc and D 5 cc ), and volume of the lungs receiving at least 20 Gy (lung V 20 ). Statistical significance was tested using Wilcoxon signed rank test at the significance level of 0.05. Overall, small differences were found in all dosimetric matrices at all rotational offsets: 95.6% of differences were 100% , PTV D max , cord D 0.35 cc , esophagus D 0.35 cc , esophagus D 5 cc , and lung V 20 was − 8.36%, − 6.06%, 11.96%, 8.66%, 6.02%, and − 0.69%, respectively. No significant correlation was found between any dosimetric change and tumor-to-cord/esophagus distances (R 2 range: 0 to 0.44). Larger dosimetric changes and intersubject variations were observed at larger rotational offsets. Small dosimetric differences were found owing to rotational offsets up to 5° in lung SBRT for medially located tumors. Larger intersubject variations were observed at larger rotational offsets

Organ motion study and dosimetric impact of respiratory gating radiotherapy for esophageal cancer; Etude de mobilite organique et impact dosimetrique de l'asservissement respiratoire dans la radiotherapie des cancers de l'oesophage

Energy Technology Data Exchange (ETDEWEB)

Lorchel, F

2007-04-15

Chemoradiotherapy is now the standard treatment for locally advanced or inoperable esophageal carcinoma. In this indication, conformal radiotherapy is generally used. However, prognosis remains poor for these patients. Respiratory gating radiotherapy can decrease healthy tissues irradiation and allows escalation dose in lung, liver and breast cancer. In order to improve radiotherapy technique, we propose to study the feasibility of respiratory gating for esophageal cancer. We will study the respiratory motions of esophageal cancer to optimize target volume delineation, especially the internal margin (I.M.). We will test the correlation between tumour and chest wall displacements to prove that esophageal cancer motions are induced by respiration. This is essential before using free breathing respiratory gating systems. We will work out the dosimetric impact of respiratory gating using various dosimetric analysis parameters. We will compare dosimetric plans at end expiration, end inspiration and deep inspiration with dosimetric plan in free-breathing condition. This will allow us to establish the best respiratory phase to irradiate for each gating system. This dosimetric study will be completed with linear quadratic equivalent uniform dose (E.U.D.) calculation for each volume of interest. Previously, we will do a theoretical study of histogram dose volume gradation to point up its use. (author)

Dosimetric comparison of partial and whole breast external beam irradiation in the treatment of early stage breast cancer

International Nuclear Information System (INIS)

Kim, Yongbok; Parda, David S.; Trombetta, Mark G.; Colonias, Athanasios; Werts, E. Day; Miller, Linda; Miften, Moyed

2007-01-01

A dosimetric comparison was performed on external-beam three-dimensional conformal partial breast irradiation (PBI) and whole breast irradiation (WBI) plans for patients enrolled in the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-39/Radiation Therapy Oncology Group (RTOG) 0413 protocol at our institution. Twenty-four consecutive patients were treated with either PBI (12 patients) or WBI (12 patients). In the PBI arm, the lumpectomy cavity was treated to a total dose of 38.5 Gy at 3.85 Gy per fraction twice daily using a four-field noncoplanar beam setup. A minimum 6 h interval was required between fractions. In the WBI arm, the whole breast including the entirety of the lumpectomy cavity was treated to a total dose of 50.4 Gy at 1.8 Gy per fraction daily using opposed tangential beams. The lumpectomy cavity volume, planning target volume for evaluation (PTV E VAL), and critical structure volumes were contoured for both the PBI and WBI patients. Dosimetric parameters, dose volume histograms (DVHs), and generalized equivalent uniform dose (gEUD) for target and critical structures were compared. Dosimetric results show the PBI plans, compared to the WBI plans, have smaller hot spots in the PTV E VAL (maximum dose: 104.2% versus 110.9%) and reduced dose to the ipsilateral breast (V50: 48.6% versus 92.1% and V100: 10.2% versus 50.5%), contralateral breast (V3: 0.16% versus 2.04%), ipsilateral lung (V30: 5.8% versus 12.7%), and thyroid (maximum dose: 0.5% versus 2.0%) with p values ≤0.01. However, similar dose coverage of the PTV E VAL (98% for PBI and 99% for WBI, on average) was observed and the dose difference for other critical structures was clinically insignificant in both arms. The gEUD data analysis showed the reduction of dose to the ipsilateral breast and lung, contralateral breast and thyroid. In addition, preliminary dermatologic adverse event assessment data suggested reduced skin toxicity for patients treated with the PBI technique

Toxicity and dosimetric analysis of non-small cell lung cancer patients undergoing radiotherapy with 4DCT and image-guided intensity modulated radiotherapy: a regional centre's experience.

Science.gov (United States)

Livingston, Gareth C; Last, Andrew J; Shakespeare, Thomas P; Dwyer, Patrick M; Westhuyzen, Justin; McKay, Michael J; Connors, Lisa; Leader, Stephanie; Greenham, Stuart

2016-09-01

For patients receiving radiotherapy for locally advance non-small cell lung cancer (NSCLC), the probability of experiencing severe radiation pneumonitis (RP) appears to rise with an increase in radiation received by the lungs. Intensity modulated radiotherapy (IMRT) provides the ability to reduce planned doses to healthy organs at risk (OAR) and can potentially reduce treatment-related side effects. This study reports toxicity outcomes and provides a dosimetric comparison with three-dimensional conformal radiotherapy (3DCRT). Thirty curative NSCLC patients received radiotherapy using four-dimensional computed tomography and five-field IMRT. All were assessed for early and late toxicity using common terminology criteria for adverse events. All plans were subsequently re-planned using 3DCRT to the same standard as the clinical plans. Dosimetric parameters for lungs, oesophagus, heart and conformity were recorded for comparison between the two techniques. IMRT plans achieved improved high-dose conformity and reduced OAR doses including lung volumes irradiated to 5-20 Gy. One case each of oesophagitis and erythema (3%) were the only Grade 3 toxicities. Rates of Grade 2 oesophagitis were 40%. No cases of Grade 3 RP were recorded and Grade 2 RP rates were as low as 3%. IMRT provides a dosimetric benefit when compared to 3DCRT. While the clinical benefit appears to increase with increasing target size and increasing complexity, IMRT appears preferential to 3DCRT in the treatment of NSCLC.

A dosimetric comparison of 3D conformal vs intensity modulated vs volumetric arc radiation therapy for muscle invasive bladder cancer

International Nuclear Information System (INIS)

Foroudi, Farshad; Kron, Tomas; Wilson, Lesley; Bressel, Mathias; Haworth, Annette; Hornby, Colin; Pham, Daniel; Cramb, Jim; Gill, Suki; Tai, Keen Hun

2012-01-01

To compare 3 Dimensional Conformal radiotherapy (3D-CRT) with Intensity Modulated Radiotherapy (IMRT) with Volumetric-Modulated Arc Therapy (VMAT) for bladder cancer. Radiotherapy plans for 15 patients with T2-T4N0M0 bladder cancer were prospectively developed for 3-DCRT, IMRT and VMAT using Varian Eclipse planning system. The same radiation therapist carried out all planning and the same clinical dosimetric constraints were used. 10 of the patients with well localised tumours had a simultaneous infield boost (SIB) of the primary tumour planned for both IMRT and VMAT. Tumour control probabilities and normal tissue complication probabilities were calculated. Mean planning time for 3D-CRT, IMRT and VMAT was 30.0, 49.3, and 141.0 minutes respectively. The mean PTV conformity (CI) index for 3D-CRT was 1.32, for IMRT 1.05, and for VMAT 1.05. The PTV Homogeneity (HI) index was 0.080 for 3D-CRT, 0.073 for IMRT and 0.086 for VMAT. Tumour control and normal tissue complication probabilities were similar for 3D-CRT, IMRT and VMAT. The mean monitor units were 267 (range 250–293) for 3D-CRT; 824 (range 641–1083) for IMRT; and 403 (range 333–489) for VMAT (P < 0.05). Average treatment delivery time were 2:25min (range 2:01–3:09) for 3D-CRT; 4:39 (range 3:41–6:40) for IMRT; and 1:14 (range 1:13–1:14) for VMAT. In selected patients, the SIB did not result in a higher dose to small bowel or rectum. VMAT is associated with similar dosimetric advantages as IMRT over 3D-CRT for muscle invasive bladder cancer. VMAT is associated with faster delivery times and less number of mean monitor units than IMRT. SIB is feasible in selected patients with localized tumours

Dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer

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Yang, Yun; Catalano, Suzanne; Kelsey, Chris R.; Yoo, David S.; Yin, Fang-Fang; Cai, Jing, E-mail: jing.cai@duke.edu

2014-04-01

To quantitatively evaluate dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer. Overall, 11 lung SBRT patients (8 female and 3 male; mean age: 75.0 years) with medially located tumors were included. Treatment plans with simulated rotational offsets of 1°, 3°, and 5° in roll, yaw, and pitch were generated and compared with the original plans. Both clockwise and counterclockwise rotations were investigated. The following dosimetric metrics were quantitatively evaluated: planning target volume coverage (PTV V{sub 100%}), max PTV dose (PTV D{sub max}), percentage prescription dose to 0.35 cc of cord (cord D{sub 0.35} {sub cc}), percentage prescription dose to 0.35 cc and 5 cc of esophagus (esophagus D{sub 0.35} {sub cc} and D{sub 5} {sub cc}), and volume of the lungs receiving at least 20 Gy (lung V{sub 20}). Statistical significance was tested using Wilcoxon signed rank test at the significance level of 0.05. Overall, small differences were found in all dosimetric matrices at all rotational offsets: 95.6% of differences were < 1% or < 1 Gy. Of all rotational offsets, largest change in PTV V{sub 100%}, PTV D{sub max}, cord D{sub 0.35} {sub cc}, esophagus D{sub 0.35} {sub cc}, esophagus D{sub 5} {sub cc}, and lung V{sub 20} was − 8.36%, − 6.06%, 11.96%, 8.66%, 6.02%, and − 0.69%, respectively. No significant correlation was found between any dosimetric change and tumor-to-cord/esophagus distances (R{sup 2} range: 0 to 0.44). Larger dosimetric changes and intersubject variations were observed at larger rotational offsets. Small dosimetric differences were found owing to rotational offsets up to 5° in lung SBRT for medially located tumors. Larger intersubject variations were observed at larger rotational offsets.

Single-fraction flattening filter–free volumetric modulated arc therapy for lung cancer: Dosimetric results and comparison with flattened beams technique

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Barbiero, Sara [Medical Physics Division, Centro di Riferimento Oncologico, Aviano (Italy); Specialty School in Medical Physics, University of Pisa, Pisa (Italy); Rink, Alexandra [Radiation Physics Department, Princess Margaret Cancer Centre, University Health Network, Toronto (Canada); Department of Radiation Oncology, University of Toronto, Toronto (Canada); Matteucci, Fabrizio [Radiation Oncology Department, S.Chiara University Hospital, Pisa (Italy); Fedele, David [Radiotherapy Department, Casa di Cura S. Rossore, Pisa (Italy); Paiar, Fabiola; Pasqualetti, Francesco [Radiation Oncology Department, S.Chiara University Hospital, Pisa (Italy); Avanzo, Michele, E-mail: mavanzo@cro.it [Medical Physics Division, Centro di Riferimento Oncologico, Aviano (Italy)

2016-01-01

Purpose: To report on single-fraction stereotactic body radiotherapy (RT) (SBRT) with flattening filter (FF)–free (FFF) volumetric modulated arc therapy (VMAT) for lung cancer and to compare dosimetric results with VMAT with FF. Methods and materials: Overall, 25 patients were treated with 6-MV FFF VMAT (Varian TrueBeam STx LINAC) to a prescribed dose of 24 Gy in a single fraction. Treatment plans were recreated using FF VMAT. Dose-volume indices, monitor units (MU), and treatment times were compared between FFF and FF VMAT techniques. Results: Dose constraints to PTV, spinal cord, and lungs were reached in FFF and FF plans. In FFF plans, average conformity index was 1.13 (95% CI: 1.07 to1.38). Maximum doses to spinal cord, heart, esophagus, and trachea were 2.9 Gy (95% CI: 0.4 to 6.7 Gy), 0.8 Gy (95% CI: 0 to 3.6 Gy), 3.3 Gy (95% CI: 0.02 to 13.9 Gy), and 1.5 Gy (95% CI: 0 to 4.9 Gy), respectively. Average V7 Gy, V7.4 Gy, and mean dose to the healthy lung were 126.5 cc (95% CI: 41.3 to 248.9 cc), 107.3 cc (95% CI: 18.7 to 232.8 cc), and 1.1 Gy (95% CI: 0.3 to 2.2 Gy), respectively. No statistically significant differences were found in dosimetric results and MU between FF and FFF treatments. Treatment time was reduced by an average factor of 2.31 (95% CI: 2.15 to 2.43) from FF treatments to FFF, and the difference was statistically significant. Conclusions: FFF VMAT for lung SBRT provides equivalent dosimetric results to the target and organs at risk as FF VMAT while significantly reducing treatment time.

SU-E-T-125: Dosimetric Comparison of Intensity Modulated Radiation Therapy Using Robotic Versus Traditional Linac Platform in Prostate Cancer

International Nuclear Information System (INIS)

Hayes, T; Rella, J; Yang, J; Sims, C; Fung, C

2014-01-01

Purpose: Recent development of an MLC for robotic external beam radiotherapy has the potential of new clinical application in conventionally fractionated radiation therapy. This study offers a dosimetric comparison of IMRT plans using Cyberknife with MLC versus conventional linac plans. Methods: Ten prostate cancer patients treated on a traditional linac with IMRT to 7920cGy at 180cGy/fraction were randomly selected. GTVs were defined as prostate plus proximal seminal vesicles. PTVs were defined as GTV+8mm in all directions except 5mm posteriorly. Conventional IMRT planning was performed on Philips Pinnacle and delivered on a standard linac with CBCT and 10mm collimator leaf width. For each case a Cyberknife plan was created using Accuray Multiplan with same CT data set, contours, and dose constraints. All dosimetric data was transferred to third party software for independent computation of contour volumes and DVH. Delivery efficiency was evaluated using total MU, treatment time, number of beams, and number of segments. Results: Evaluation criteria including percent target coverage, homogeneity index, and conformity index were found to be comparable. All dose constraints from QUANTEC were found to be statistically similar except rectum V50Gy and bladder V65Gy. Average rectum V50Gy was lower for robotic IMRT (30.07%±6.57) versus traditional (34.73%±3.62, p=0.0130). Average bladder V65Gy was lower for robotic (17.87%±12.74) versus traditional (21.03%±11.93, p=0.0405). Linac plans utilized 9 coplanar beams, 48.9±3.8 segments, and 19381±2399MU. Robotic plans utilized 38.4±9.0 non-coplanar beams, 85.5±21.0 segments and 42554.71±16381.54 MU. The average treatment was 15.02±0.60 minutes for traditional versus 20.90±2.51 for robotic. Conclusion: The robotic IMRT plans were comparable to the traditional IMRT plans in meeting the target volume dose objectives. Critical structure dose constraints were largely comparable although statistically significant

Effect of stereotactic dosimetric end points on overall survival for Stage I non–small cell lung cancer: A critical review

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Mulryan, Kathryn; Leech, Michelle; Forde, Elizabeth, E-mail: eforde@tcd.ie

2015-01-01

Stereotactic body radiation therapy (SBRT) delivers a high biologically effective dose while minimizing toxicities to surrounding tissues. Within the scope of clinical trials and local practice, there are inconsistencies in dosimetrics used to evaluate plan quality. The purpose of this critical review was to determine if dosimetric parameters used in SBRT plans have an effect on local control (LC), overall survival (OS), and toxicities. A database of relevant trials investigating SBRT for patients with early-stage non–small cell lung cancer was compiled, and a table of dosimetric variables used was created. These parameters were compared and contrasted for LC, OS, and toxicities. Dosimetric end points appear to have no effect on OS or LC. Incidences of rib fractures correlate with a lack of dose-volume constraints (DVCs) reported. This review highlights the great disparity present in clinical trials reporting dosimetrics, DVCs, and toxicities for lung SBRT. Further evidence is required before standard DVCs guidelines can be introduced. Dosimetric end points specific to stereotactic treatment planning have been proposed but require further investigation before clinical implementation.

Dose-to-medium vs. dose-to-water: Dosimetric evaluation of dose reporting modes in Acuros XB for prostate, lung and breast cancer

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Suresh Rana

2014-12-01

Full Text Available Purpose: Acuros XB (AXB dose calculation algorithm is available for external beam photon dose calculations in Eclipse treatment planning system (TPS. The AXB can report the absorbed dose in two modes: dose-to-water (Dw and dose-to-medium (Dm. The main purpose of this study was to compare the dosimetric results of the AXB_Dm with that of AXB_Dw on real patient treatment plans. Methods: Four groups of patients (prostate cancer, stereotactic body radiation therapy (SBRT lung cancer, left breast cancer, and right breast cancer were selected for this study, and each group consisted of 5 cases. The treatment plans of all cases were generated in the Eclipse TPS. For each case, treatment plans were computed using AXB_Dw and AXB_Dm for identical beam arrangements. Dosimetric evaluation was done by comparing various dosimetric parameters in the AXB_Dw plans with that of AXB_Dm plans for the corresponding patient case. Results: For the prostate cancer, the mean planning target volume (PTV dose in the AXB_Dw plans was higher by up to 1.0%, but the mean PTV dose was within ±0.3% for the SBRT lung cancer. The analysis of organs at risk (OAR results in the prostate cancer showed that AXB_Dw plans consistently produced higher values for the bladder and femoral heads but not for the rectum. In the case of SBRT lung cancer, a clear trend was seen for the heart mean dose and spinal cord maximum dose, with AXB_Dw plans producing higher values than the AXB_Dm plans. However, the difference in the lung doses between the AXB_Dm and AXB_Dw plans did not always produce a clear trend, with difference ranged from -1.4% to 2.9%. For both the left and right breast cancer, the AXB_Dm plans produced higher maximum dose to the PTV for all cases. The evaluation of the maximum dose to the skin showed higher values in the AXB_Dm plans for all 5 left breast cancer cases, whereas only 2 cases had higher maximum dose to the skin in the AXB_Dm plans for the right breast cancer

Is there room for combined modality treatments? Dosimetric comparison of boost strategies for advanced head and neck and prostate cancer

International Nuclear Information System (INIS)

Gora, Joanna; Hopfgartner, Johannes; Kuess, Peter; Paskeviciute, Brigita; Georg, Dietmar

2013-01-01

The purpose of the study was to determine the dosimetric difference between three emerging treatment modalities-volumetric-modulated arc therapy (VMAT), intensity-modulated proton beam therapy (IMPT) and intensity-modulated carbon ion beam therapy (IMIT)-for two tumour sites where selective boosting of the tumour is applied. For 10 patients with locally advanced head and neck (H and N) cancer and 10 with high-risk prostate cancer (PC) a VMAT plan was generated for PTV initial that included lymph node regions, delivering 50 Gy (IsoE) for H and N and 50.4 Gy (IsoE) for PC patients. Furthermore, separate boost plans (VMAT, IMPT and IMIT) were created to boost PTV boost up to 70 Gy (IsoE) and 78 Gy (IsoE) for H and N and PC cases, respectively. Doses to brainstem, myelon, larynx and parotid glands were assessed for H and N cases. Additionally, various organs at risk (OARs) (e.g. cochlea, middle ear, masticator space) were evaluated that are currently discussed with respect to quality of life after treatment. For PC cases, bladder, rectum and femoral heads were considered as OARs. For both tumour sites target goals were easily met. Looking at OAR sparing, generally VMAT + VMAT was worst. VMAT + IMIT had the potential to spare some structures in very close target vicinity (such as cochlea, middle ear, masticator space) significantly better than VMAT + IMPT. Mean doses for rectal and bladder wall were on average 4 Gy (IsoE) and 1.5 Gy (IsoE) higher, respectively, compared to photons plus particles scenarios. Similar results were found for parotid glands and larynx. Concerning target coverage, no significant differences were observed between the three treatment concepts. Clear dosimetric benefits were observed for particle beam therapy as boost modality. However, the clinical benefit of combined modality treatments remains to be demonstrated. (author)

Dosimetric Comparison of 6 MV and 15 MV Single Arc Rapidarc to Helical TomoTherapy for the Treatment of Pancreatic Cancer

International Nuclear Information System (INIS)

Cai Jing; Yue Jinbo; McLawhorn, Robert; Yang Wensha; Wijesooriya, Krishni; Dunlap, Neal E.; Sheng Ke; Yin Fangfang; Benedict, Stanley H.

2011-01-01

We conducted a planning study to compare Varian's RapidArc (RA) and helical TomoTherapy (HT) for the treatment of pancreatic cancer. Three intensity-modulated radiotherapy (IMRT) plans were generated for 8 patients with pancreatic cancer: one using HT with 6-MV beam (Plan HT6 ), one using single-arc RA with 6-MV beam (Plan RA6 ), and one using single-arc RA with 15-MV beam (Plan RA15 ). Dosimetric indices including high/low conformality index (CI 100% /CI 50% ), heterogeneity index (HI), monitor units (MUs), and doses to organs at risk (OARs) were compared. The mean CI 100% was statistically equivalent with respect to the 2 treatment techniques, as well as beam energy (0.99, 1.01, and 1.02 for Plan HT6 , Plan RA6 , and Plan RA156, respectively). The CI 50% and HI were improved in both RA plans over the HT plan. The RA plans significantly reduced MU (MU RA6 = 697, MU RA15 = 548) compared with HT (MU HT6 = 6177, p = 0.008 in both cases). The mean maximum cord dose was decreased from 29.6 Gy in Plan H T6 to 21.6 Gy (p = 0.05) in Plan RA6 and 21.7 Gy (p = 0.04) in Plan RA15 . The mean bowel dose decreased from 17.2 Gy in Plan HT6 to 15.2 Gy (p = 0.03) in Plan RA6 and 15.0 Gy (p = 0.03) Plan RA15 . The mean liver dose decreased from 8.4 Gy in Plan HT6 to 6.3 Gy (p = 0.04) in Plan RA6 and 6.2 Gy in Plan RA15 . Variations of the mean dose to the duodenum, kidneys, and stomach were statistically insignificant. RA and HT can both deliver conformal dose distributions to target volumes while limiting the dose to surrounding OARs in the treatment of pancreatic cancer. Dosimetric advantages might be gained by using RA over HT by reducing the dose to OARs and total MUs used for treatment.

Dosimetric comparison of axilla and groin radiotherapy techniques for high-risk and locally advanced skin cancer

International Nuclear Information System (INIS)

Mattes, Malcolm D.; Zhou, Ying; Berry, Sean L.; Barker, Christopher A.

2016-01-01

Radiation therapy targeting axilla and groin lymph nodes improves regional disease control in locally advanced and high-risk skin cancers. However, trials generally used conventional two-dimensional radiotherapy (2D-RT), contributing towards relatively high rates of side effects from treatment. The goal of this study is to determine if three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), or volumetric-modulated arc therapy (VMAT) may improve radiation delivery to the target while avoiding organs at risk in the clinical context of skin cancer regional nodal irradiation. Twenty patients with locally advanced/high-risk skin cancers underwent computed tomography simulation. The relevant axilla or groin planning target volumes and organs at risk were delineated using standard definitions. Paired t-tests were used to compare the mean values of several dose-volumetric parameters for each of the 4 techniques. In the axilla, the largest improvement for 3D-CRT compared to 2D-RT was for homogeneity index (13.9 vs. 54.3), at the expense of higher lung V 20 (28.0% vs. 12.6%). In the groin, the largest improvements for 3D-CRT compared to 2D-RT were for anorectum D max (13.6 vs. 38.9 Gy), bowel D 200cc (7.3 vs. 23.1 Gy), femur D 50 (34.6 vs. 57.2 Gy), and genitalia D max (37.6 vs. 51.1 Gy). IMRT had further improvements compared to 3D-CRT for humerus D mean (16.9 vs. 22.4 Gy), brachial plexus D 5 (57.4 vs. 61.3 Gy), bladder D 5 (26.8 vs. 36.5 Gy), and femur D 50 (18.7 vs. 34.6 Gy). Fewer differences were observed between IMRT and VMAT. Compared to 2D-RT and 3D-CRT, IMRT and VMAT had dosimetric advantages in the treatment of nodal regions of skin cancer patients

Dosimetric comparison of axilla and groin radiotherapy techniques for high-risk and locally advanced skin cancer

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Mattes, Malcolm D.; Zhou, Ying; Berry, Sean L.; Barker, Christopher A. [Memorial Sloan Kettering Cancer Center, New York (United States)

2016-06-15

Radiation therapy targeting axilla and groin lymph nodes improves regional disease control in locally advanced and high-risk skin cancers. However, trials generally used conventional two-dimensional radiotherapy (2D-RT), contributing towards relatively high rates of side effects from treatment. The goal of this study is to determine if three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), or volumetric-modulated arc therapy (VMAT) may improve radiation delivery to the target while avoiding organs at risk in the clinical context of skin cancer regional nodal irradiation. Twenty patients with locally advanced/high-risk skin cancers underwent computed tomography simulation. The relevant axilla or groin planning target volumes and organs at risk were delineated using standard definitions. Paired t-tests were used to compare the mean values of several dose-volumetric parameters for each of the 4 techniques. In the axilla, the largest improvement for 3D-CRT compared to 2D-RT was for homogeneity index (13.9 vs. 54.3), at the expense of higher lung V{sub 20} (28.0% vs. 12.6%). In the groin, the largest improvements for 3D-CRT compared to 2D-RT were for anorectum D{sub max} (13.6 vs. 38.9 Gy), bowel D{sub 200cc} (7.3 vs. 23.1 Gy), femur D{sub 50} (34.6 vs. 57.2 Gy), and genitalia D{sub max} (37.6 vs. 51.1 Gy). IMRT had further improvements compared to 3D-CRT for humerus D{sub mean} (16.9 vs. 22.4 Gy), brachial plexus D{sub 5} (57.4 vs. 61.3 Gy), bladder D{sub 5} (26.8 vs. 36.5 Gy), and femur D{sub 50} (18.7 vs. 34.6 Gy). Fewer differences were observed between IMRT and VMAT. Compared to 2D-RT and 3D-CRT, IMRT and VMAT had dosimetric advantages in the treatment of nodal regions of skin cancer patients.

Comparison of dosimetric methods for virtual wedge analysis

International Nuclear Information System (INIS)

Bailey, M.; Nelson, V.; Collins, O.; West, M.; Holloway, L.; Rajapaske, S.; Arts, J.; Varas, J.; Cho, G.; Hill, R.

2004-01-01

Full text: The Siemens Virtual Wedge (Concord, USA) creates wedged beam profile by moving a single collimator jaw across the specified field size whilst varying the dose rate and jaw speed for use in the delivery of radiotherapy treatments. The measurement of the dosimetric characteristics of the Siemens Virtual Wedge poses significant challenges to medical physicists. This study investigates several different methods for measuring and analysing the virtual wedge for data collection for treatment planning systems and ongoing quality assurance. The beam profiles of the Virtual Wedge (VW) were compared using several different dosimetric methods. Open field profiles were measured with Kodak X-Omat V (Rochester, NY, USA) radiographic film and compared with measurements made using the Sun Nuclear Profiler with a Motorized Drive Assembly (MDA) (Melbourne, FL, USA) and the Scanditronix Wellhofer CC13 ionisation chamber and 24 ion Chamber Array (CA24) (Schwarzenbruck, Germany). The resolution of each dosimetric method for open field profiles was determined. The Virtual Wedge profiles were measured with radiographic film the Profiler and the Scanditronix Wellhofer CA 24 ion Chamber Array at 5 different depths. The ease of setup, time taken, analysis and accuracy of measurement were all evaluated to determine the method that would be both appropriate and practical for routine quality assurance of the Virtual Wedge. The open field profiles agreed within ±2% or 2mm for all dosimetric methods. The accuracy of the Profiler and CA24 are limited to half of the step size selected for each of these detectors. For the VW measurements a step size of 2mm was selected for the Profiler and the CA24. The VW profiles for all dosimetric methods agreed within ±2% or 2mm for the main wedged section of the profile. The toe and heel ends of the wedges showed the significant discrepancies dependent upon the dosimetry method used, up to 7% for the toe end with the CA24. The dosimetry of the

Dosimetric Comparison of Split Field and Fixed Jaw Techniques for Large IMRT Target Volumes in the Head and Neck

International Nuclear Information System (INIS)

Srivastava, Shiv P.; Das, Indra J.; Kumar, Arvind; Johnstone, Peter A.S.

2011-01-01

Some treatment planning systems (TPSs), when used for large-field (>14 cm) intensity-modulated radiation therapy (IMRT), create split fields that produce excessive multiple-leaf collimator segments, match-line dose inhomogeneity, and higher treatment times than nonsplit fields. A new method using a fixed-jaw technique (FJT) forces the jaw to stay at a fixed position during optimization and is proposed to reduce problems associated with split fields. Dosimetric comparisons between split-field technique (SFT) and FJT used for IMRT treatment is presented. Five patients with head and neck malignancies and regional target volumes were studied and compared with both techniques. Treatment planning was performed on an Eclipse TPS using beam data generated for Varian 2100C linear accelerator. A standard beam arrangement consisting of nine coplanar fields, equally spaced, was used in both techniques. Institutional dose-volume constraints used in head and neck cancer were kept the same for both techniques. The dosimetric coverage for the target volumes between SFT and FJT for head and neck IMRT plan is identical within ±1% up to 90% dose. Similarly, the organs at risk (OARs) have dose-volume coverage nearly identical for all patients. When the total monitor unit (MU) and segments were analyzed, SFT produces statistically significant higher segments (17.3 ± 6.3%) and higher MU (13.7 ± 4.4%) than the FJT. There is no match line in FJT and hence dose uniformity in the target volume is superior to the SFT. Dosimetrically, SFT and FJT are similar for dose-volume coverage; however, the FJT method provides better logistics, lower MU, shorter treatment time, and better dose uniformity. The number of segments and MU also has been correlated with the whole body radiation dose with long-term complications. Thus, FJT should be the preferred option over SFT for large target volumes.

Radiotherapy for gastric mucosa-associated lymphoid tissue lymphoma: Dosimetric comparison and risk assessment of solid secondary cancer

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Bae, Sun Hyun; Park, Hee Chul; Lim, Do Hoon [Dept. of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kim, Dong Wook [Dept. of Radiation Oncology, Kyung Hee University Hospital at Gangdong, Seoul (Korea, Republic of); Kim, Mi Sook [Dept. of Radiation Oncology, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Shin, Myung Hee [Dept. of Social and Preventive Medicine, Sungkyunkwan University School of Medicine, Suwon (Korea, Republic of)

2017-03-15

We compared the dosimetric parameters and the risk of solid secondary cancer from scattered doses among anterior-posterior/posterior-anterior parallel-opposed fields (AP/PA), anterior, posterior, right, and left lateral fields (4{sub f}ield), 3-dimensional conformal radiotherapy (3D-CRT) using noncoplanar beams, and intensity-modulated radiotherapy composed of 7 coplanar beams (IMRT{sub c}o) and 7 coplanar and noncoplanar beams (IMRT{sub n}on). We retrospectively generated 5 planning techniques for 5 patients with gastric MALToma. Homogeneity index (HI), conformity index (CI), and mean doses of the kidney and liver were calculated from the dose-volume histograms. Applied the Biological Effects of Ionizing Radiation VII report to scattered doses, the lifetime attributable risk (LAR) was calculated to estimate the risk of solid secondary cancer. The best value of CI was obtained with IMRT, although the HI varied among patients. The mean kidney dose was the highest with AP/PA, followed by 4{sub f}ield, 3D-CRT, IMRT{sub c}o, and IMRT{sub n}on. On the other hand, the mean liver dose was the highest with 4{sub f}ield and the lowest with AP/PA. Compared with 4{sub f}ield, the LAR for 3D-CRT decreased except the lungs, and the LAR for IMRT{sub c}o and IMRT{sub n}on increased except the lungs. However, the absolute differences were much lower than <1%. Tailored RT techniques seem to be beneficial because it could achieve adjacent organ sparing with very small and clinically irrelevant increase of secondary solid cancer risk compared to the conventional techniques.

Dosimetric impact of mixed-energy volumetric modulated arc therapy plans for high-risk prostate cancer

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Shyam Pokharel

2013-10-01

Full Text Available Purpose: This study investigated the dosimetric impact of mixing low and high energy treatment plans for prostate cancer treated with volumetric modulated arc therapy (VMAT technique in the form of RapidArc.Methods: A cohort of 12 prostate cases involving proximal seminal vesicles and lymph nodes was selected for this retrospective study. For each prostate case, the single-energy plans (SEPs and mixed-energy plans (MEPs were generated.  First, the SEPs were created using 6 mega-voltage (MV energy for both the primary and boost plans. Second, the MEPs were created using 16 MV energy for the primary plan and 6 MV energy for the boost plan. The primary and boost MEPs used identical beam parameters and same dose optimization values as in the primary and boost SEPs for the corresponding case. The dosimetric parameters from the composite plans (SEPs and MEPs were evaluated. Results: The dose to the target volume was slightly higher (on average <1% in the SEPs than in the MEPs. The conformity index (CI and homogeneity index (HI values between the SEPs and MEPs were comparable. The dose to rectum and bladder was always higher in the SEPs (average difference up to 3.7% for the rectum and up to 8.4% for the bladder than in the MEPs. The mean dose to femoral heads was higher by about 0.8% (on average in the MEPs than in the SEPs. The number of monitor units and integral dose were higher in the SEPs compared to the MEPs by average differences of 9.1% and 5.5%, respectively.Conclusion: The preliminary results from this study suggest that use of mixed-energy VMAT plan for high-risk prostate cancer could potentially reduce the integral dose and minimize the dose to rectum and bladder, but for the higher femoral head dose.-----------------------------------------------Cite this article as:Pokharel S. Dosimetric impact of mixed-energy volumetric modulated arc therapy plans for high-risk prostate cancer. Int J Cancer Ther Oncol 2013;1(1:01011.DOI: http

Dosimetric comparison of proton and photon three-dimensional, conformal, external beam accelerated partial breast irradiation techniques

International Nuclear Information System (INIS)

Kozak, Kevin R.; Katz, Angela; Adams, Judith C.; Crowley, Elizabeth M.; Nyamwanda, Jacqueline A.C.; Feng, Jennifer K.C.; Doppke, Karen P.; DeLaney, Thomas F.; Taghian, Alphonse G.

2006-01-01

Purpose: To compare the dosimetry of proton and photon-electron three-dimensional, conformal, external beam accelerated partial breast irradiation (3D-CPBI). Methods and Materials: Twenty-four patients with fully excised, Stage I breast cancer treated with adjuvant proton 3D-CPBI had treatment plans generated using the mixed-modality, photon-electron 3D-CPBI technique. To facilitate dosimetric comparisons, planning target volumes (PTVs; lumpectomy site plus 1.5-2.0 cm margin) and prescribed dose (32 Gy) were held constant. Plans were optimized for PTV coverage and normal tissue sparing. Results: Proton and mixed-modality plans both provided acceptable PTV coverage with 95% of the PTV receiving 90% of the prescribed dose in all cases. Both techniques also provided excellent dose homogeneity with a dose maximum exceeding 110% of the prescribed dose in only one case. Proton 3D-CPBI reduced the volume of nontarget breast tissue receiving 50% of the prescribed dose by an average of 36%. Statistically significant reductions in the volume of total ipsilateral breast receiving 100%, 75%, 50%, and 25% of the prescribed dose were also observed. The use of protons resulted in small, but statistically significant, reductions in the radiation dose delivered to 5%, 10%, and 20% of ipsilateral and contralateral lung and heart. The nontarget breast tissue dosimetric advantages of proton 3D-CPBI were not dependent on tumor location, breast size, PTV size, or the ratio of PTV to breast volume. Conclusions: Compared to photon-electron 3D-CPBI, proton 3D-CPBI significantly reduces the volume of irradiated nontarget breast tissue. Both approaches to accelerated partial breast irradiation offer exceptional lung and heart sparing

Characterizing Interfraction Variations and Their Dosimetric Effects in Prostate Cancer Radiotherapy

International Nuclear Information System (INIS)

Peng Cheng; Ahunbay, Ergun; Chen Guangpei; Anderson, Savannah; Lawton, Colleen; Li, X. Allen

2011-01-01

Purpose: To quantitatively characterize the interfraction variations and their dosimetric effects in radiotherapy for prostate cancer. Methods and Materials: A total of 486 daily computed tomography (CT) sets acquired for 20 prostate cancer patients treated with daily CT-guided repositioning using a linear accelerator and CT-on-rail combination were analyzed. The prostate, rectum, and bladder, delineated on each daily CT data set, were compared with those from the planning CT scan. Several quantities, including Dice's coefficient and the maximal overlapping rate, were used to characterize the interfraction variations. The delivered dose was reconstructed by applying the original plan to the daily CT scan with consideration of proper repositioning. Results: The mean prostate Dice's coefficient and maximal overlapping rate after bony registration was 69.7% ± 13.8% (standard deviation) and 85.6% ± 7.8% (standard deviation), respectively. The daily delivered dose distributions were generally inferior to the planned dose distribution for target coverage and/or normal structure sparing. For example, for approximately 5% of the treatment fractions, the prostate volume receiving 100% of the prescription dose decreased dramatically (15-20%) compared with its planned value. The magnitudes of the interfraction variations and their dosimetric effects indicated that, statistically, current standard repositioning using prostate alignment might be adequate for two-thirds of the fractions, but for the rest of the fractions, better on-line correction strategies, such as on-line replanning, are needed. Conclusion: Different adaptive correction schemes for prostatic interfraction changes can be used according to the anatomic changes, as quantified by the organ displacement and deformation parameters. On-line replanning is needed for approximately one-third of the treatment fractions.

Dosimetric Evaluation of Automatic Segmentation for Adaptive IMRT for Head-and-Neck Cancer

International Nuclear Information System (INIS)

Tsuji, Stuart Y.; Hwang, Andrew; Weinberg, Vivian; Yom, Sue S.; Quivey, Jeanne M.; Xia Ping

2010-01-01

Purpose: Adaptive planning to accommodate anatomic changes during treatment requires repeat segmentation. This study uses dosimetric endpoints to assess automatically deformed contours. Methods and Materials: Sixteen patients with head-and-neck cancer had adaptive plans because of anatomic change during radiotherapy. Contours from the initial planning computed tomography (CT) were deformed to the mid-treatment CT using an intensity-based free-form registration algorithm then compared with the manually drawn contours for the same CT using the Dice similarity coefficient and an overlap index. The automatic contours were used to create new adaptive plans. The original and automatic adaptive plans were compared based on dosimetric outcomes of the manual contours and on plan conformality. Results: Volumes from the manual and automatic segmentation were similar; only the gross tumor volume (GTV) was significantly different. Automatic plans achieved lower mean coverage for the GTV: V95: 98.6 ± 1.9% vs. 89.9 ± 10.1% (p = 0.004) and clinical target volume: V95: 98.4 ± 0.8% vs. 89.8 ± 6.2% (p 3 of the spinal cord 39.9 ± 3.7 Gy vs. 42.8 ± 5.4 Gy (p = 0.034), but no difference for the remaining structures. Conclusions: Automatic segmentation is not robust enough to substitute for physician-drawn volumes, particularly for the GTV. However, it generates normal structure contours of sufficient accuracy when assessed by dosimetric end points.

Matched-pair analysis and dosimetric variations of two types of software for interstitial permanent brachytherapy for prostate cancer

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Ishiyama, Hiromichi, E-mail: hishiyam@kitasato-u.ac.jp [Department of Radiology, Kitasato University School of Medicine, Sagamihara, Kanagawa (Japan); Nakamura, Ryuji [Department of Radiology, Iwate Medical University, Morioka, Iwate (Japan); Satoh, Takefumi [Department of Urology, Kitasato University School of Medicine, Sagamihara, Kanagawa (Japan); Tanji, Susumu [Department of Urology, Iwate Medical University, Morioka, Iwate (Japan); Teh, Bin S. [Department of Radiation Oncology, The Methodist Hospital, Houston, TX (United States); Uemae, Mineko [Division of Radiation Oncology, Kitasato University Hospital, Sagamihara, Kanagawa (Japan); Baba, Shiro [Department of Urology, Kitasato University School of Medicine, Sagamihara, Kanagawa (Japan); Hayakawa, Kazushige [Department of Radiology, Kitasato University School of Medicine, Sagamihara, Kanagawa (Japan)

2012-04-01

The purpose of this study was to determine whether identical dosimetric results could be achieved using different planning software for permanent interstitial brachytherapy for prostate cancer. Data from 492 patients treated with brachytherapy were used for matched-pair analysis. Interplant and Variseed were used as software for ultrasound-based treatment planning. Institution, neoadjuvant hormonal therapy, prostate volume, and source strength were used for factors to match the 2 groups. The study population comprised of 126 patients with treatment planning using Interplant software and 127 matched patients using Variseed software. Dosimetric results were compared between the 2 groups. The Variseed group showed significantly higher values for dose covering 90% of prostate volume (pD90), prostate volume covered by 150% of prescription dose (pV150), and dose covering 30% of the urethra (uD30) compared with the Interplant group. Our results showed that use of different software could lead to different dosimetric results, which might affect the clinical outcomes.

Forward-planned intensity modulated radiation therapy using a cobalt source: A dosimetric study in breast cancer

Directory of Open Access Journals (Sweden)

Savino Cilla

2013-01-01

Full Text Available This analysis evaluates the feasibility and dosimetric results of a simplified intensity-modulated radiotherapy (IMRT treatment using a cobalt-therapy unit for post-operative breast cancer. Fourteen patients were included. Three plans per patient were produced by a cobalt-60 source: A standard plan with two wedged tangential beams, a standard tangential plan optimized without the use of wedges and a plan based on the forward-planned "field-in-field" IMRT technique (Co-FinF where the dose on each of the two tangential beams was split into two different segments and the two segments weight was determined with an iterative process. For comparison purposes, a 6-MV photon standard wedged tangential treatment plan was generated. D mean , D 98% , D 2% , V 95% , V 107%, homogeneity, and conformity indices were chosen as parameters for comparison. Co-FinF technique improved the planning target volume dose homogeneity compared to other cobalt-based techniques and reduced maximum doses (D 2% and high-dose volume (V 110% . Moreover, it showed a better lung and heart dose sparing with respect to the standard approach. The higher dose homogeneity may encourage the adoption of accelerated-hypofractionated treatments also with the cobalt sources. This approach can promote the spread of breast conservative treatment in developing countries.

Can dosimetric parameters predict acute hematologic toxicity in rectal cancer patients treated with intensity-modulated pelvic radiotherapy?

International Nuclear Information System (INIS)

Wan, Juefeng; Liu, Kaitai; Li, Kaixuan; Li, Guichao; Zhang, Zhen

2015-01-01

To identify dosimetric parameters associated with acute hematologic toxicity (HT) in rectal cancer patients undergoing concurrent chemotherapy and intensity-modulated pelvic radiotherapy. Ninety-three rectal cancer patients receiving concurrent capecitabine and pelvic intensity-modulated radiation therapy (IMRT) were analyzed. Pelvic bone marrow (PBM) was contoured for each patient and divided into three subsites: lumbosacral spine (LSS), ilium, and lower pelvis (LP). The volume of each site receiving 5–40 Gy (V 5, V10, V15, V20, V30, and V40, respectively) as well as patient baseline clinical characteristics was calculated. The endpoint for hematologic toxicity was grade ≥ 2 (HT2+) leukopenia, neutropenia, anemia or thrombocytopenia. Logistic regression was used to analyze correlation between dosimetric parameters and grade ≥ 2 hematologic toxicity. Twenty-four in ninety-three patients experienced grade ≥ 2 hematologic toxicity. Only the dosimetric parameter V40 of lumbosacral spine was correlated with grade ≥ 2 hematologic toxicity. Increased pelvic lumbosacral spine V40 (LSS-V40) was associated with an increased grade ≥ 2 hematologic toxicity (p = 0.041). Patients with LSS-V40 ≥ 60 % had higher rates of grade ≥ 2 hematologic toxicity than did patients with lumbosacral spine V40 < 60 % (38.3 %, 18/47 vs.13 %, 6/46, p =0.005). On univariate and multivariate logistic regression analysis, lumbosacral spine V40 and gender was also the variable associated with grade ≥ 2 hematologic toxicity. Female patients were observed more likely to have grade ≥ 2 hematologic toxicity than male ones (46.9 %, 15/32 vs 14.8 %, 9/61, p =0.001). Lumbosacral spine -V40 was associated with clinically significant grade ≥ 2 hematologic toxicity. Keeping the lumbosacral spine -V40 < 60 % was associated with a 13 % risk of grade ≥ 2 hematologic toxicity in rectal cancer patients undergoing concurrent chemoradiotherapy

SU-E-J-21: Setup Variability of Colorectal Cancer Patients Treated in the Prone Position and Dosimetric Comparison with the Supine Position

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Kim, A; Foster, J; Chu, W; Karotki, A [Sunnybrook Health Sciences Centre/Odette Cancer Centre, Toronto, Ontario (Canada)

2015-06-15

Purpose: Many cancer centers treat colorectal patients in the prone position on a belly board to minimize dose to the small bowel. That may potentially Result in patient setup instability with corresponding impact on dose delivery accuracy for highly conformal techniques such as IMRT/VMAT. Two aims of this work are 1) to investigate setup accuracy of rectum patients treated in the prone position on a belly board using CBCT and 2) to evaluate dosimetric impact on bladder and small bowel of treating rectum patients in supine vs. prone position. Methods: For the setup accuracy study, 10 patients were selected. Weekly CBCTs were acquired and matched to bone. The CBCT-determined shifts were recorded. For the dosimetric study, 7 prone-setup patients and 7 supine-setup patients were randomly selected from our clinical database. Various clinically relevant dose volume histogram values were recorded for the small bowel and bladder. Results: The CBCT-determined rotational shifts had a wide variation. For the dataset acquired at the time of this writing, the ranges of rotational setup errors for pitch, roll, and yaw were [−3.6° 4.7°], [−4.3° 3.2°], and [−1.4° 1.4°]. For the dosimetric study: the small bowel V(45Gy) and mean dose for the prone position was 5.6±12.1% and 18.4±6.2Gy (ranges indicate standard deviations); for the supine position the corresponding dose values were 12.9±15.8% and 24.7±8.8Gy. For the bladder, the V(30Gy) and mean dose for prone position were 68.7±12.7% and 38.4±3.3Gy; for supine position these dose values were 77.1±13.7% and 40.7±3.1Gy. Conclusion: There is evidence of significant rotational instability in the prone position. The OAR dosimetry study indicates that there are some patients that may still benefit from the prone position, though many patients can be safely treated supine.

Neo-adjuvant chemo-radiation of rectal cancer with Volumetric Modulated Arc Therapy: summary of technical and dosimetric features and early clinical experience

International Nuclear Information System (INIS)

Richetti, Antonella; Fogliata, Antonella; Clivio, Alessandro; Nicolini, Giorgia; Pesce, Gianfranco; Salati, Emanuela; Vanetti, Eugenio; Cozzi, Luca

2010-01-01

To report about initial technical and clinical experience in preoperative radiation treatment of rectal cancer with volumetric modulated arcs with the RapidArc ® (RA) technology. Twenty-five consecutive patients (pts) were treated with RA. All showed locally advanced rectal adenocarcinoma with stage T2-T4, N0-1. Dose prescription was 44 Gy in 22 fractions (or 45 Gy in 25 fractions). Delivery was performed with single arc with a 6 MV photon beam. Twenty patients were treated preoperatively, five did not receive surgery. Twenty-three patients received concomitant chemotherapy with oral capecitabine. A comparison with a cohort of twenty patients with similar characteristics treated with conformal therapy (3DC) is presented as well. From a dosimetric point of view, RA improved conformality of doses (CI 95% = 1.1 vs. 1.4 for RA and 3DC), presented similar target coverage with lower maximum doses, significant sparing of femurs and significant reduction of integral and mean dose to healthy tissue. From the clinical point of view, surgical reports resulted in a down-staging in 41% of cases. Acute toxicity was limited to Grade 1-2 diarrhoea in 40% and Grade 3 in 8% of RA pts, 45% and 5% of 3DC pts, compatible with known effects of concomitant chemotherapy. RA treatments were performed with an average of 2.0 vs. 3.4 min of 3DC. RA proved to be a safe, qualitatively advantageous treatment modality for rectal cancer, showing some improved results in dosimetric aspects

Neo-adjuvant chemo-radiation of rectal cancer with Volumetric Modulated Arc Therapy: summary of technical and dosimetric features and early clinical experience

Directory of Open Access Journals (Sweden)

Salati Emanuela

2010-02-01

Full Text Available Abstract Background To report about initial technical and clinical experience in preoperative radiation treatment of rectal cancer with volumetric modulated arcs with the RapidArc® (RA technology. Methods Twenty-five consecutive patients (pts were treated with RA. All showed locally advanced rectal adenocarcinoma with stage T2-T4, N0-1. Dose prescription was 44 Gy in 22 fractions (or 45 Gy in 25 fractions. Delivery was performed with single arc with a 6 MV photon beam. Twenty patients were treated preoperatively, five did not receive surgery. Twenty-three patients received concomitant chemotherapy with oral capecitabine. A comparison with a cohort of twenty patients with similar characteristics treated with conformal therapy (3DC is presented as well. Results From a dosimetric point of view, RA improved conformality of doses (CI95% = 1.1 vs. 1.4 for RA and 3DC, presented similar target coverage with lower maximum doses, significant sparing of femurs and significant reduction of integral and mean dose to healthy tissue. From the clinical point of view, surgical reports resulted in a down-staging in 41% of cases. Acute toxicity was limited to Grade 1-2 diarrhoea in 40% and Grade 3 in 8% of RA pts, 45% and 5% of 3DC pts, compatible with known effects of concomitant chemotherapy. RA treatments were performed with an average of 2.0 vs. 3.4 min of 3DC. Conclusion RA proved to be a safe, qualitatively advantageous treatment modality for rectal cancer, showing some improved results in dosimetric aspects.

Contura Multi-Lumen Balloon Breast Brachytherapy Catheter: Comparative Dosimetric Findings of a Phase 4 Trial

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Arthur, Douglas W., E-mail: darthur@mcvh-vcu.edu [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States); Vicini, Frank A. [Michigan Healthcare Professionals/21st Century Oncology, Farmington Hills, Michigan (United States); Todor, Dorin A. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States); Julian, Thomas B. [Allegheny General Hospital, Temple University School of Medicine, Pittsburgh, Pennsylvania (United States); Cuttino, Laurie W.; Mukhopadhyay, Nitai D. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States)

2013-06-01

Purpose: Final dosimetric findings of a completed, multi-institutional phase 4 registry trial using the Contura Multi-Lumen Balloon (MLB) breast brachytherapy catheter to deliver accelerated partial breast irradiation (APBI) in patients with early-stage breast cancer are presented. Methods and Materials: Three dosimetric plans with identical target coverage were generated for each patient for comparison: multilumen multidwell (MLMD); central-lumen multidwell (CLMD); and central-lumen single-dwell (CLSD) loading of the Contura catheter. For this study, a successful treatment plan achieved ideal dosimetric goals and included the following: ≥95% of the prescribed dose (PD) covering ≥95% of the target volume (TV); maximum skin dose ≤125% of the PD; maximum rib dose ≤145% of the PD; and V150 ≤50 cc and V200 ≤10 cc. Results: Between January 2008 and February 2011, 23 institutions participated. A total of 318 patients were available for dosimetric review. Using the Contura MLB, all dosimetric criteria were met in 78.93% of cases planned with MLMD versus 55.38% with the CLMD versus 37.66% with the CLSD (P≤.0001). Evaluating all patients with the full range of skin to balloon distance represented, median maximum skin dose was reduced by 12% and median maximum rib dose by 13.9% when using MLMD-based dosimetric plans compared to CLSD. The dosimetric benefit of MLMD was further demonstrated in the subgroup of patients where skin thickness was <5 mm, where MLMD use allowed a 38% reduction in median maximum skin dose over CLSD. For patients with rib distance <5 mm, the median maximum rib dose reduction was 27%. Conclusions: Use of the Contura MLB catheter produced statistically significant improvements in dosimetric capabilities between CLSD and CLMD treatments. This device approach demonstrates the ability not only to overcome the barriers of limited skin thickness and close rib proximity, but to consistently achieve a higher standard of dosimetric planning goals.

Contura Multi-Lumen Balloon breast brachytherapy catheter: comparative dosimetric findings of a phase 4 trial.

Science.gov (United States)

Arthur, Douglas W; Vicini, Frank A; Todor, Dorin A; Julian, Thomas B; Cuttino, Laurie W; Mukhopadhyay, Nitai D

2013-06-01

Final dosimetric findings of a completed, multi-institutional phase 4 registry trial using the Contura Multi-Lumen Balloon (MLB) breast brachytherapy catheter to deliver accelerated partial breast irradiation (APBI) in patients with early-stage breast cancer are presented. Three dosimetric plans with identical target coverage were generated for each patient for comparison: multilumen multidwell (MLMD); central-lumen multidwell (CLMD); and central-lumen single-dwell (CLSD) loading of the Contura catheter. For this study, a successful treatment plan achieved ideal dosimetric goals and included the following: ≥ 95% of the prescribed dose (PD) covering ≥ 95% of the target volume (TV); maximum skin dose ≤ 125% of the PD; maximum rib dose ≤ 145% of the PD; and V150 ≤50 cc and V200 ≤ 10 cc. Between January 2008 and February 2011, 23 institutions participated. A total of 318 patients were available for dosimetric review. Using the Contura MLB, all dosimetric criteria were met in 78.93% of cases planned with MLMD versus 55.38% with the CLMD versus 37.66% with the CLSD (P ≤.0001). Evaluating all patients with the full range of skin to balloon distance represented, median maximum skin dose was reduced by 12% and median maximum rib dose by 13.9% when using MLMD-based dosimetric plans compared to CLSD. The dosimetric benefit of MLMD was further demonstrated in the subgroup of patients where skin thickness was <5 mm, where MLMD use allowed a 38% reduction in median maximum skin dose over CLSD. For patients with rib distance <5 mm, the median maximum rib dose reduction was 27%. Use of the Contura MLB catheter produced statistically significant improvements in dosimetric capabilities between CLSD and CLMD treatments. This device approach demonstrates the ability not only to overcome the barriers of limited skin thickness and close rib proximity, but to consistently achieve a higher standard of dosimetric planning goals. Copyright © 2013 Elsevier Inc. All rights

Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer

Energy Technology Data Exchange (ETDEWEB)

Yang, Ruijie, E-mail: ruijyang@yahoo.com; Zhao, Nan; Liao, Anyan; Wang, Hao; Qu, Ang

2016-10-01

To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5 mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78 Gy in 39 fractions were prescribed for PTV. For HDR and LDR plans, the dose prescription was D{sub 90} of 34 Gy in 8.5 Gy per fraction, and 145 Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2 Gy per fraction, EQD{sub 2}) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The D{sub mean} (EQD{sub 2}) of rectum decreased 22.36 Gy in HDR and 17.01 Gy in LDR from 30.24 Gy in VMAT, respectively. The D{sub mean} (EQD{sub 2}) of bladder decreased 6.91 Gy in HDR and 2.53 Gy in LDR from 13.46 Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD{sub 2}) was 80.26, 70.23, and 104.91 Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR.

Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer

International Nuclear Information System (INIS)

Yang, Ruijie; Zhao, Nan; Liao, Anyan; Wang, Hao; Qu, Ang

2016-01-01

To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5 mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78 Gy in 39 fractions were prescribed for PTV. For HDR and LDR plans, the dose prescription was D 90 of 34 Gy in 8.5 Gy per fraction, and 145 Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2 Gy per fraction, EQD 2 ) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The D mean (EQD 2 ) of rectum decreased 22.36 Gy in HDR and 17.01 Gy in LDR from 30.24 Gy in VMAT, respectively. The D mean (EQD 2 ) of bladder decreased 6.91 Gy in HDR and 2.53 Gy in LDR from 13.46 Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD 2 ) was 80.26, 70.23, and 104.91 Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR.

Clinical and dosimetric predictors of acute hematologic toxicity in rectal cancer patients undergoing chemoradiotherapy

International Nuclear Information System (INIS)

Yang, T. Jonathan; Oh, Jung Hun; Apte, Aditya; Son, Christina H.; Deasy, Joseph O.; Goodman, Karyn A.

2014-01-01

Background and purpose: To identify clinical and dosimetric factors associated with hematologic toxicity (HT) during chemoradiotherapy for rectal cancer. Materials and methods: We analyzed 120 rectal cancer patients treated with neoadjuvant pelvic radiotherapy (PRT) with concurrent 5-fluorouracil-based chemotherapy. The coxal (ilium, ischium, and pubis) bone marrow (BM), sacral BM, and femoral BM were contoured and dose-volume parameters were extracted. Associations between cell count trend and clinical predictors were tested using repeated-measures analysis of variance (ANOVA) test. Associations between clinical variables, Vx (percentage volume receiving x Gy), and cell count ratio at nadir were tested using linear regression models. Results: Nadirs for white blood cell count (WBC), absolute neutrophil count (ANC), and platelets (PLT) occurred in the second week of PRT and the fifth week for hemoglobin and absolute lymphocyte count (ALC). Using cell count ratio, patients treated with 3DCRT had a lower WBC ratio trend during PRT compared to patients treated with IMRT (p = 0.04), and patients ⩾59 years of age had a lower hemoglobin ratio trend during PRT (p = 0.02). Using absolute cell count, patients treated with 3DCRT had lower ANC cell count trend (p = 0.03), and women had lower hemoglobin cell count trend compared to men (p = 0.03). On univariate analysis, use of 3DCRT was associated with a lower WBC ratio at nadir (p = 0.02). On multiple regression analysis using dosimetric variables, coxal BM V45 (p = 0.03) and sacral BM V45 (p = 0.03) were associated with a lower WBC and ANC ratio at nadir, respectively. Conclusions: HT trends during PRT revealed distinct patterns: WBC, ANC, and PLT cell counts reach nadirs early and recover, while hemoglobin and ALC decline steadily. Patients who were treated with 3DCRT and older patients experienced lower cell count ratio trend during PRT. Dosimetric constraints using coxal BM V45 and sacral BM V45 can be considered

Dosimetric characteristics of biological effect of sulfur-35

International Nuclear Information System (INIS)

Borisova, V.V.

1990-01-01

Experimental materials related to evaluation of dosimetric characteristics of sulfur-35 are presented. Hemogenic organs are subjected to greatest influence especially in the first hours after radionuclide entry into the organism. Comparison is made of absorbed doses in blood with observed blastomogen effect of hemogenic organs. It is noted, that quantitative evaluation of relative biological efficiency of low energy beta-emitters should be performed with account of dosimetric peculiarities of the nuclides mentioned above. 10 refs.; 3 tabs

Dosimetric improvements following 3D planning of tangential breast irradiation

International Nuclear Information System (INIS)

Aref, Amr; Thornton, Dale; Youssef, Emad; He, Tony; Tekyi-Mensah, Samuel; Denton, Lori; Ezzell, Gary

2000-01-01

Purpose: To evaluate the dosimetric difference between a simple radiation therapy plan utilizing a single contour and a more complex three-dimensional (3D) plan utilizing multiple contours, lung inhomogeneity correction, and dose-based compensators. Methods and Materials: This is a study of the radiation therapy (RT) plans of 85 patients with early breast cancer. All patients were considered for breast-conserving management and treated by conventional tangential fields technique. Two plans were generated for each patient. The first RT plan was based on a single contour taken at the central axis and utilized two wedges. The second RT plan was generated by using the 3D planning system to design dose-based compensators after lung inhomogeneity correction had been made. The endpoints of the study were the comparison between the volumes receiving greater than 105% and greater than 110% of the reference dose, as well as the magnitude of the treated volume maximum dose. Dosimetric improvement was defined to be of significant value if the volume receiving > 105% of one plan was reduced by at least 50% with the absolute difference between the volumes being 5% or greater. The dosimetric improvements in 49 3D plans (58%) were considered of significant value. Patients' field separation and breast size did not predict the magnitude of improvement in dosimetry. Conclusion: Dose-based compensator plans significantly reduced the volumes receiving > 105%, >110%, and volume maximum dose.

A dose-volume histogram based decision-support system for dosimetric comparison of radiotherapy treatment plans

International Nuclear Information System (INIS)

Alfonso, J. C. L.; Herrero, M. A.; Núñez, L.

2015-01-01

The choice of any radiotherapy treatment plan is usually made after the evaluation of a few preliminary isodose distributions obtained from different beam configurations. Despite considerable advances in planning techniques, such final decision remains a challenging task that would greatly benefit from efficient and reliable assessment tools. For any dosimetric plan considered, data on dose-volume histograms supplied by treatment planning systems are used to provide estimates on planning target coverage as well as on sparing of organs at risk and the remaining healthy tissue. These partial metrics are then combined into a dose distribution index (DDI), which provides a unified, easy-to-read score for each competing radiotherapy plan. To assess the performance of the proposed scoring system, DDI figures for fifty brain cancer patients were retrospectively evaluated. Patients were divided in three groups depending on tumor location and malignancy. For each patient, three tentative plans were designed and recorded during planning, one of which was eventually selected for treatment. We thus were able to compare the plans with better DDI scores and those actually delivered. When planning target coverage and organs at risk sparing are considered as equally important, the tentative plan with the highest DDI score is shown to coincide with that actually delivered in 32 of the 50 patients considered. In 15 (respectively 3) of the remaining 18 cases, the plan with highest DDI value still coincides with that actually selected, provided that organs at risk sparing is given higher priority (respectively, lower priority) than target coverage. DDI provides a straightforward and non-subjective tool for dosimetric comparison of tentative radiotherapy plans. In particular, DDI readily quantifies differences among competing plans with similar-looking dose-volume histograms and can be easily implemented for any tumor type and localization, irrespective of the planning system and

Study of dosimetric parameters for iodine-125 brachytherapy sources development from IPEN-CNEN/SP using Monte Carlo method

International Nuclear Information System (INIS)

Oliveira, Tiago Batista de

2016-01-01

Expectations of the World Health Organization for the year 2030 are that the number of cancer deaths is approximately 13.2 million, reflecting the high proportion of this disease in global health issue. With respect to prostate cancer, according to the National Cancer Institute, the number of cases diagnosed worldwide in 2012 was approximately 1.1 million, while in Brazil the data demonstrated the incidence of 68,000 new cases. The treatment of cancer can be performed with surgery (prostatectomy) or radiation therapy. Among radiotherapy, we can highlight the brachytherapy technique, which consists in the introduction of small radioactive sources (seeds) within the prostate, which is delivered a high dose value in the treatment volume and low dose in the surrounding tissues. In Brazil, the medical profession estimates a demand of approximately 8000 seeds / month, and the unit cost of each seed at least US $ 26.00. The AAPM protocol TG-43 recommend the dose-rate constant, radial dose function and anisotropy function for dosimetric analysis LDR brachytherapy seeds. In this work, Monte Carlo simulations were performed in order to assess the dosimetric parameters of the OncoSeed-6711, manufactured by Oncura-GEHealthcare, and a seed developed by Radiation Technology Center, using the MCNP5 code. A 6711 seed, an IPEN seed and the 30 x 30 x 30cm 3 phantom filled with water were modeled to simulate the dose distribution. The 6711 seed parameters were compared with literature, and the results presented relative error less than 0.1% for Λ. In comparison with the 6711 seed, the IPEN model seed dosimetric parameters were similar, account the statistical uncertainty. (author)

Dosimetric comparison of interactive planned and dynamic dose calculated prostate seed brachytherapy

International Nuclear Information System (INIS)

Meijer, Gert J.; Berg, Hetty A. van den; Hurkmans, Coen W.; Stijns, Pascal E.; Weterings, Jan H.

2006-01-01

Purpose: To compare the dosimetrical results of an interactive planning procedure and a procedure based on dynamic dose calculation for permanent prostate brachytherapy. Materials and methods: Between 6/2000 and 11/2005, 510 patients underwent 125 I implants for T1-T2 prostate cancer. Before 4/2003, 187 patients were treated using an interactive technique that included needle updating. After that period, 323 patients were treated with a more refined dynamic technique that included constant updating of the deposited seed position. The comparison is based on postimplant dose-volume parameters such as the V 100 and d 90 for the target, V 100 r for the rectum and d 10 u for the urethra. Furthermore, the target volume ratios (TVR=V 100 body /V 100 ), and the homogeneity indices (HI=[V 100 -V 150 ]/V 100 ) were calculated as additional quality parameters. Results: The dose outside the target volume was significantly reduced, the V 100 r decreased from 1.4cm 3 for the interactive technique to 0.6cm 3 for the dynamic technique. Similarly the mean TVR reduced from 1.66 to 1.44. In addition, the mean V 100 increased from 92% for the interactive procedure to 95% for the dynamic procedure. More importantly, the percentage of patients with a V 100 10 u (136% vs. 140%) and the HI (0.58 vs. 0.51). Conclusion: The dynamic implant procedure resulted in improved implants. Almost ideal dose coverage was achieved, while minimizing the dose outside the prostate

Postoperative Radiotherapy for Prostate Cancer: A Comparison of Four Consensus Guidelines and Dosimetric Evaluation of 3D-CRT Versus Tomotherapy IMRT

International Nuclear Information System (INIS)

Malone, Shawn; Croke, Jennifer; Roustan-Delatour, Nicolas; Belanger, Eric; Avruch, Leonard; Malone, Colin; Morash, Christopher; Kayser, Cathleen; Underhill, Kathryn; Li Yan; Malone, Kyle; Nyiri, Balazs; Spaans, Johanna

2012-01-01

Purpose: Despite the benefits of adjuvant radiotherapy after radical prostatectomy, approximately one-half of patients relapse. Four consensus guidelines have been published (European Organization for Research and Treatment of Cancer, Faculty of Radiation Oncology Genito-Urinary Group, Princess Margaret Hospital, Radiation Therapy Oncology Group) with the aim of standardizing the clinical target volume (CTV) delineation and improve outcomes. To date, no attempt has been made to compare these guidelines in terms of treatment volumes or organ at risk (OAR) irradiation. The extent to which the guideline-derived plans meet the dosimetric constraints of present trials or of the Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) trial is also unknown. Our study also explored the dosimetric benefits of intensity-modulated radiotherapy (IMRT). Methods and Materials: A total of 20 patients treated with postoperative RT were included. The three-dimensional conformal radiotherapy (3D-CRT) plans were applied to cover the guideline-generated planning target volumes (66 Gy in 33 fractions). Dose–volume histograms (DVHs) were analyzed for CTV/planning target volume coverage and to evaluate OAR irradiation. The OAR DVHs were compared with the constraints proposed in the QUANTEC and Radiotherapy and Androgen Deprivation In Combination After Local Surgery (RADICALS) trials. 3D-CRT plans were compared with the tomotherapy plans for the Radiation Therapy Oncology Group planning target volume to evaluate the advantages of IMRT. Results: The CTV differed significantly between guidelines (p < 0.001). The European Organization for Research and Treatment of Cancer-CTVs were significantly smaller than the other CTVs (p < 0.001). Differences in prostate bed coverage superiorly accounted for the major volumetric differences between the guidelines. Using 3D-CRT, the DVHs rarely met the QUANTEC or RADICALS rectal constraints, independent of the guideline used. The RADICALS

Dosimetric Comparison of Real-Time MRI-Guided Tri-Cobalt-60 Versus Linear Accelerator-Based Stereotactic Body Radiation Therapy Lung Cancer Plans.

Science.gov (United States)

Wojcieszynski, Andrzej P; Hill, Patrick M; Rosenberg, Stephen A; Hullett, Craig R; Labby, Zacariah E; Paliwal, Bhudatt; Geurts, Mark W; Bayliss, R Adam; Bayouth, John E; Harari, Paul M; Bassetti, Michael F; Baschnagel, Andrew M

2017-06-01

Magnetic resonance imaging-guided radiation therapy has entered clinical practice at several major treatment centers. Treatment of early-stage non-small cell lung cancer with stereotactic body radiation therapy is one potential application of this modality, as some form of respiratory motion management is important to address. We hypothesize that magnetic resonance imaging-guided tri-cobalt-60 radiation therapy can be used to generate clinically acceptable stereotactic body radiation therapy treatment plans. Here, we report on a dosimetric comparison between magnetic resonance imaging-guided radiation therapy plans and internal target volume-based plans utilizing volumetric-modulated arc therapy. Ten patients with early-stage non-small cell lung cancer who underwent radiation therapy planning and treatment were studied. Following 4-dimensional computed tomography, patient images were used to generate clinically deliverable plans. For volumetric-modulated arc therapy plans, the planning tumor volume was defined as an internal target volume + 0.5 cm. For magnetic resonance imaging-guided plans, a single mid-inspiratory cycle was used to define a gross tumor volume, then expanded 0.3 cm to the planning tumor volume. Treatment plan parameters were compared. Planning tumor volumes trended larger for volumetric-modulated arc therapy-based plans, with a mean planning tumor volume of 47.4 mL versus 24.8 mL for magnetic resonance imaging-guided plans ( P = .08). Clinically acceptable plans were achievable via both methods, with bilateral lung V20, 3.9% versus 4.8% ( P = .62). The volume of chest wall receiving greater than 30 Gy was also similar, 22.1 versus 19.8 mL ( P = .78), as were all other parameters commonly used for lung stereotactic body radiation therapy. The ratio of the 50% isodose volume to planning tumor volume was lower in volumetric-modulated arc therapy plans, 4.19 versus 10.0 ( P guided tri-cobalt-60 radiation therapy is capable of delivering lung high

Treatment of Non-Small Cell Lung Cancer Patients With Proton Beam-Based Stereotactic Body Radiotherapy: Dosimetric Comparison With Photon Plans Highlights Importance of Range Uncertainty

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Seco, Joao, E-mail: jseco@partners.org [Department of Radiation Oncology, Harvard Medical School and Massachusetts General Hospital, Boston, MA (United States); Panahandeh, Hamid Reza [Department of Radiation Oncology, Harvard Medical School and Massachusetts General Hospital, Boston, MA (United States); Westover, Kenneth [Department of Radiation Oncology, Harvard Medical School and Massachusetts General Hospital, Boston, MA (United States); Harvard Radiation Oncology Program, Harvard Medical School, Boston, MA (United States); Adams, Judith; Willers, Henning [Department of Radiation Oncology, Harvard Medical School and Massachusetts General Hospital, Boston, MA (United States)

2012-05-01

Purpose: Proton beam radiotherapy has been proposed for use in stereotactic body radiotherapy (SBRT) for early-stage non-small-cell lung cancer. In the present study, we sought to analyze how the range uncertainties for protons might affect its therapeutic utility for SBRT. Methods and Materials: Ten patients with early-stage non-small-cell lung cancer received SBRT with two to three proton beams. The patients underwent repeat planning for photon SBRT, and the dose distributions to the normal and tumor tissues were compared with the proton plans. The dosimetric comparisons were performed within an operational definition of high- and low-dose regions representing volumes receiving >50% and <50% of the prescription dose, respectively. Results: In high-dose regions, the average volume receiving {>=}95% of the prescription dose was larger for proton than for photon SBRT (i.e., 46.5 cm{sup 3} vs. 33.5 cm{sup 3}; p = .009, respectively). The corresponding conformity indexes were 2.46 and 1.56. For tumors in close proximity to the chest wall, the chest wall volume receiving {>=}30 Gy was 7 cm{sup 3} larger for protons than for photons (p = .06). In low-dose regions, the lung volume receiving {>=}5 Gy and maximum esophagus dose were smaller for protons than for photons (p = .019 and p < .001, respectively). Conclusions: Protons generate larger high-dose regions than photons because of range uncertainties. This can result in nearby healthy organs (e.g., chest wall) receiving close to the prescription dose, at least when two to three beams are used, such as in our study. Therefore, future research should explore the benefit of using more than three beams to reduce the dose to nearby organs. Additionally, clinical subgroups should be identified that will benefit from proton SBRT.

Dosimetric comparison of standard bi-dimensional radiotherapy, mono-isocentric three-dimensional and arc-therapy for a bilateral breast cancer case with ganglionary attack; Comparaison dosimetrique pour un cas de cancer du sein bilateral avec atteinte ganglionnaire de la radiotherapie bidimensionnelle standard, la radiotherapie tridimensionnelle mono-isocentrique et l'arctherapie

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Arnaud, A. [Centre Leon-Berard, Lyon (France); Bodez, V.; Alric, K.; Chastel, D.; Mege, A. [Institut Sainte-Catherine, Avignon (France)

2011-10-15

The authors report a study which aimed at determining the optimal radiotherapy technique for a patient operated from a bilateral breast cancer with ganglionary attack and peculiar thoracic conformation. A dosimetric study has been performed. Target volumes and lung and heart coverages have been compared for three techniques: bi-dimensional and three-dimensional radiotherapy, and arc-therapy. It appears that arc-therapy would allow a dosimetric and therapeutic duration gain without improving the target volume coverage while increasing doses delivered to organs at risk. Short communication

Dosimetric and radiobiological comparison of TG-43 and Monte Carlo calculations in 192Ir breast brachytherapy applications.

Science.gov (United States)

Peppa, V; Pappas, E P; Karaiskos, P; Major, T; Polgár, C; Papagiannis, P

2016-10-01

To investigate the clinical significance of introducing model based dose calculation algorithms (MBDCAs) as an alternative to TG-43 in 192 Ir interstitial breast brachytherapy. A 57 patient cohort was used in a retrospective comparison between TG-43 based dosimetry data exported from a treatment planning system and Monte Carlo (MC) dosimetry performed using MCNP v. 6.1 with plan and anatomy information in DICOM-RT format. Comparison was performed for the target, ipsilateral lung, heart, skin, breast and ribs, using dose distributions, dose-volume histograms (DVH) and plan quality indices clinically used for plan evaluation, as well as radiobiological parameters. TG-43 overestimation of target DVH parameters is statistically significant but small (less than 2% for the target coverage indices and 4% for homogeneity indices, on average). Significant dose differences (>5%) were observed close to the skin and at relatively large distances from the implant leading to a TG-43 dose overestimation for the organs at risk. These differences correspond to low dose regions (<50% of the prescribed dose), being less than 2% of the prescribed dose. Detected dosimetric differences did not induce clinically significant differences in calculated tumor control probabilities (mean absolute difference <0.2%) and normal tissue complication probabilities. While TG-43 shows a statistically significant overestimation of most indices used for plan evaluation, differences are small and therefore not clinically significant. Improved MBDCA dosimetry could be important for re-irradiation, technique inter-comparison and/or the assessment of secondary cancer induction risk, where accurate dosimetry in the whole patient anatomy is of the essence. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Comparison of MRI-based and CT/MRI fusion-based postimplant dosimetric analysis of prostate brachytherapy

International Nuclear Information System (INIS)

Tanaka, Osamu; Hayashi, Shinya; Matsuo, Masayuki; Sakurai, Kota; Nakano, Masahiro; Maeda, Sunaho; Kajita, Kimihiro R.T.; Deguchi, Takashi; Hoshi, Hiroaki

2006-01-01

Purpose: The aim of this study was to compare the outcomes between magnetic resonance imaging (MRI)-based and computed tomography (CT)/MRI fusion-based postimplant dosimetry methods in permanent prostate brachytherapy. Methods and Materials: Between October 2004 and March 2006, a total of 52 consecutive patients with prostate cancer were treated by brachytherapy, and postimplant dosimetry was performed using CT/MRI fusion. The accuracy and reproducibility were prospectively compared between MRI-based dosimetry and CT/MRI fusion-based dosimetry based on the dose-volume histogram (DVH) related parameters as recommended by the American Brachytherapy Society. Results: The prostate volume was 15.97 ± 6.17 cc (mean ± SD) in MRI-based dosimetry, and 15.97 ± 6.02 cc in CT/MRI fusion-based dosimetry without statistical difference. The prostate V100 was 94.5% and 93.0% in MRI-based and CT/MRI fusion-based dosimetry, respectively, and the difference was statistically significant (p = 0.002). The prostate D90 was 119.4% and 114.4% in MRI-based and CT/MRI fusion-based dosimetry, respectively, and the difference was statistically significant (p = 0.004). Conclusion: Our current results suggested that, as with fusion images, MR images allowed accurate contouring of the organs, but they tended to overestimate the analysis of postimplant dosimetry in comparison to CT/MRI fusion images. Although this MRI-based dosimetric discrepancy was negligible, MRI-based dosimetry was acceptable and reproducible in comparison to CT-based dosimetry, because the difference between MRI-based and CT/MRI fusion-based results was smaller than that between CT-based and CT/MRI fusion-based results as previously reported

Dosimetric comparison between intensity modulated brachytherapy versus external beam intensity modulated radiotherapy for cervix cancer: a treatment planning study

International Nuclear Information System (INIS)

Subramani, V.; Sharma, D.N.; Jothy Basu, K.S.; Rath, G.K.; Gopishankar, N.

2008-01-01

To evaluate the dosimetric superiority of intensity modulated brachytherapy (IMBT) based on inverse planning optimization technique with classical brachytherapy optimization and also with external beam intensity modulated radiotherapy planning technique in patients of cervical carcinoma

Helical Tomotherapy Versus Single-Arc Intensity-Modulated Arc Therapy: A Collaborative Dosimetric Comparison Between Two Institutions

International Nuclear Information System (INIS)

Rong Yi; Tang, Grace; Welsh, James S.; Mohiuddin, Majid M.; Paliwal, Bhudatt; Yu, Cedric X.

2011-01-01

Purpose: Both helical tomotherapy (HT) and single-arc intensity-modulated arc therapy (IMAT) deliver radiation using rotational beams with multileaf collimators. We report a dual-institution study comparing dosimetric aspects of these two modalities. Methods and Materials: Eight patients each were selected from the University of Maryland (UMM) and the University of Wisconsin Cancer Center Riverview (UWR), for a total of 16 cases. Four cancer sites including brain, head and neck (HN), lung, and prostate were selected. Single-arc IMAT plans were generated at UMM using Varian RapidArc (RA), and HT plans were generated at UWR using Hi-Art II TomoTherapy. All 16 cases were planned based on the identical anatomic contours, prescriptions, and planning objectives. All plans were swapped for analysis at the same time after final approval. Dose indices for targets and critical organs were compared based on dose-volume histograms, the beam-on time, monitor units, and estimated leakage dose. After the disclosure of comparison results, replanning was done for both techniques to minimize diversity in optimization focus from different operators. Results: For the 16 cases compared, the average beam-on time was 1.4 minutes for RA and 4.8 minutes for HT plans. HT provided better target dose homogeneity (7.6% for RA and 4.2% for HT) with a lower maximum dose (110% for RA and 105% for HT). Dose conformation numbers were comparable, with RA being superior to HT (0.67 vs. 0.60). The doses to normal tissues using these two techniques were comparable, with HT showing lower doses for more critical structures. After planning comparison results were exchanged, both techniques demonstrated improvements in dose distributions or treatment delivery times. Conclusions: Both techniques created highly conformal plans that met or exceeded the planning goals. The delivery time and total monitor units were lower in RA than in HT plans, whereas HT provided higher target dose uniformity.

Dosimetric implications of inter- and intrafractional prostate positioning errors during tomotherapy. Comparison of gold marker-based registrations with native MVCT

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Wust, Peter; Joswig, Marc; Graf, Reinhold; Boehmer, Dirk; Beck, Marcus; Barelkowski, Thomasz; Budach, Volker; Ghadjar, Pirus [Charite Universitaetsmedizin Berlin, Department of Radiation Oncology and Radiotherapy, Berlin (Germany)

2017-09-15

For high-dose radiation therapy (RT) of prostate cancer, image-guided (IGRT) and intensity-modulated RT (IMRT) approaches are standard. Less is known regarding comparisons of different IGRT techniques and the resulting residual errors, as well as regarding their influences on dose distributions. A total of 58 patients who received tomotherapy-based RT up to 84 Gy for high-risk prostate cancer underwent IGRT based either on daily megavoltage CT (MVCT) alone (n = 43) or the additional use of gold markers (n = 15) under routine conditions. Planned Adaptive (Accuray Inc., Madison, WI, USA) software was used for elaborated offline analysis to quantify residual interfractional prostate positioning errors, along with systematic and random errors and the resulting safety margins after both IGRT approaches. Dosimetric parameters for clinical target volume (CTV) coverage and exposition of organs at risk (OAR) were also analyzed and compared. Interfractional as well as intrafractional displacements were determined. Particularly in the vertical direction, residual interfractional positioning errors were reduced using the gold marker-based approach, but dosimetric differences were moderate and the clinical relevance relatively small. Intrafractional prostate motion proved to be quite high, with displacements of 1-3 mm; however, these did not result in additional dosimetric impairments. Residual interfractional positioning errors were reduced using gold marker-based IGRT; however, this resulted in only slightly different final dose distributions. Therefore, daily MVCT-based IGRT without markers might be a valid alternative. (orig.) [German] Bei der hochdosierten Bestrahlung des Prostatakarzinoms sind die bildgesteuerte (IGRT) und die intensitaetsmodulierte Bestrahlung (IMRT) Standard. Offene Fragen gibt es beim Vergleich von IGRT-Techniken im Hinblick auf residuelle Fehler und Beeinflussungen der Dosisverteilung. Bei 58 Patienten, deren Hochrisiko-Prostatakarzinom am

A dosimetric selectivity intercomparison of HDR brachytherapy, IMRT and helical tomotherapy in prostate cancer radiotherapy

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Hermesse, Johanne; Biver, Sylvie; Jansen, Nicolas; Coucke, Philippe [Dept. of Radiation Oncology, Liege Univ. Hospital (Belgium); Lenaerts, Eric [Dept. of Medical Physics, Liege Univ. Hospital (Belgium); De Patoul, Nathalie; Vynckier, Stefaan [Dept. of Medical Physics, St Luc Univ. Hospital, Brussels (Belgium); Scalliet, Pierre [Dept. of Radiation Oncology, St Luc Univ. Hospital, Brussels (Belgium); Nickers, Philippe [Dept. of Radiation Oncology, Oscar Lambret Center, Lille (France)

2009-11-15

Background and purpose: dose escalation in order to improve the biochemical control in prostate cancer requires the application of irradiation techniques with high conformality. The dosimetric selectivity of three radiation modalities is compared: high-dose-rate brachytherapy (HDR-BT), intensity-modulated radiation radiotherapy (IMRT), and helical tomotherapy (HT). Patients and methods: ten patients with prostate adenocarcinoma treated by a 10-Gy HDR-BT boost after external-beam radiotherapy were investigated. For each patient, HDR-BT, IMRT and HT theoretical treatment plans were realized using common contour sets. A 10-Gy dose was prescribed to the planning target volume (PTV). The PTVs and critical organs' dose-volume histograms obtained were compared using Student's t-test. Results: HDR-BT delivers spontaneously higher mean doses to the PTV with smaller cold spots compared to IMRT and HT. 33% of the rectal volume received a mean HDR-BT dose of 3.86 {+-} 0.3 Gy in comparison with a mean IMRT dose of 6.57 {+-} 0.68 Gy and a mean HT dose of 5.58 {+-} 0.71 Gy (p < 0.0001). HDR-BT also enables to better spare the bladder. The hot spots inside the urethra are greater with HDR-BT. The volume of healthy tissue receiving 10% of the prescribed dose is reduced at least by a factor of 8 with HDR-BT (p < 0.0001). Conclusion: HDR-BT offers better conformality in comparison with HT and IMRT and reduces the volume of healthy tissue receiving a low dose. (orig.)

Dosimetric and Late Radiation Toxicity Comparison Between Iodine-125 Brachytherapy and Stereotactic Radiation Therapy for Juxtapapillary Choroidal Melanoma

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Krema, Hatem, E-mail: htmkrm19@yahoo.com [Department of Ocular Oncology, Princess Margaret Hospital/University Health Network, University of Toronto, Toronto, Ontario (Canada); Heydarian, Mostafa [Department of Radiation Medicine, Princess Margaret Hospital/University Health Network, University of Toronto, Toronto, Ontario (Canada); Beiki-Ardakani, Akbar [Department of Radiation Oncology, Princess Margaret Hospital/University Health Network, University of Toronto, Toronto, Ontario (Canada); Weisbrod, Daniel [Department of Ocular Oncology, Princess Margaret Hospital/University Health Network, University of Toronto, Toronto, Ontario (Canada); Xu, Wei [Department of Biostatistics, Princess Margaret Hospital/University Health Network, University of Toronto, Toronto, Ontario (Canada); Laperriere, Normand J.; Sahgal, Arjun [Department of Radiation Oncology, Princess Margaret Hospital/University Health Network, University of Toronto, Toronto, Ontario (Canada)

2013-07-01

Purpose: To compare the dose distributions and late radiation toxicities for {sup 125}I brachytherapy (IBT) and stereotactic radiation therapy (SRT) in the treatment of juxtapapillary choroidal melanoma. Methods: Ninety-four consecutive patients with juxtapapillary melanoma were reviewed: 30 have been treated with IBT and 64 with SRT. Iodine-125 brachytherapy cases were modeled with plaque simulator software for dosimetric analysis. The SRT dosimetric data were obtained from the Radionics XKnife RT3 software. Mean doses at predetermined intraocular points were calculated. Kaplan-Meier estimates determined the actuarial rates of late toxicities, and the log–rank test compared the estimates. Results: The median follow-up was 46 months in both cohorts. The 2 cohorts were balanced with respect to pretreatment clinical and tumor characteristics. Comparisons of radiation toxicity rates between the IBT and SRT cohorts yielded actuarial rates at 50 months for cataracts of 62% and 75% (P=.1), for neovascular glaucoma 8% and 47% (P=.002), for radiation retinopathy 59% and 89% (P=.0001), and for radiation papillopathy 39% and 74% (P=.003), respectively. Dosimetric comparisons between the IBT and SRT cohorts yielded mean doses of 12.8 and 14.1 Gy (P=.56) for the lens center, 17.6 and 19.7 Gy (P=.44) for the lens posterior pole, 13.9 and 10.8 Gy (P=.30) for the ciliary body, 61.9 and 69.7 Gy (P=.03) for optic disc center, and 48.9 and 60.1 Gy (P<.0001) for retina at 5-mm distance from tumor margin, respectively. Conclusions: Late radiation-induced toxicities were greater with SRT, which is secondary to the high-dose exposure inherent to the technique as compared with IBT. When technically feasible, IBT is preferred to treat juxtapapillary choroidal melanoma.

Dosimetric comparison between intra-cavitary breast brachytherapy techniques for accelerated partial breast irradiation and a novel stereotactic radiotherapy device for breast cancer: GammaPod™

Science.gov (United States)

Ödén, Jakob; Toma-Dasu, Iuliana; Yu, Cedric X.; Feigenberg, Steven J.; Regine, William F.; Mutaf, Yildirim D.

2013-07-01

The GammaPod™ device, manufactured by Xcision Medical Systems, is a novel stereotactic breast irradiation device. It consists of a hemispherical source carrier containing 36 Cobalt-60 sources, a tungsten collimator with two built-in collimation sizes, a dynamically controlled patient support table and a breast immobilization cup also functioning as the stereotactic frame for the patient. The dosimetric output of the GammaPod™ was modelled using a Monte Carlo based treatment planning system. For the comparison, three-dimensional (3D) models of commonly used intra-cavitary breast brachytherapy techniques utilizing single lumen and multi-lumen balloon as well as peripheral catheter multi-lumen implant devices were created and corresponding 3D dose calculations were performed using the American Association of Physicists in Medicine Task Group-43 formalism. Dose distributions for clinically relevant target volumes were optimized using dosimetric goals set forth in the National Surgical Adjuvant Breast and Bowel Project Protocol B-39. For clinical scenarios assuming similar target sizes and proximity to critical organs, dose coverage, dose fall-off profiles beyond the target and skin doses at given distances beyond the target were calculated for GammaPod™ and compared with the doses achievable by the brachytherapy techniques. The dosimetric goals within the protocol guidelines were fulfilled for all target sizes and irradiation techniques. For central targets, at small distances from the target edge (up to approximately 1 cm) the brachytherapy techniques generally have a steeper dose fall-off gradient compared to GammaPod™ and at longer distances (more than about 1 cm) the relation is generally observed to be opposite. For targets close to the skin, the relative skin doses were considerably lower for GammaPod™ than for any of the brachytherapy techniques. In conclusion, GammaPod™ allows adequate and more uniform dose coverage to centrally and peripherally

Dosimetric predictors of diarrhea during radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Sanguineti, Giuseppe; Endres, Eugene J.; Parker, Brent C.; Sormani, Maria Pia

2009-01-01

Purpose: to investigate dosimetric predictors of diarrhea during radiotherapy (RT) for prostate cancer. Patients and methods: all patients who underwent external-beam radiotherapy as part of treatment for localized prostate cancer at the University of Texas Medical Branch, Galveston, TX, USA, from May 2002 to November 2006 were extracted from the own database. From the cumulative dose-volume histogram (DVH), the absolute volumes (V-value) of intestinal cavity (IC) receiving 15, 30, and 45 Gy were extracted for each patient. Acute gastrointestinal toxicity was prospectively scored at each weekly treatment visit according to CTC (common toxicity criteria) v2.0. The endpoint was the development of peak grade ≥ 2 diarrhea during RT. Various patient, tumor, and treatment characteristics were evaluated using logistic regression. Results: 149 patients were included in the analysis, 112 (75.2%) treated with whole-pelvis intensity-modulated radiotherapy (WP-IMRT) and 37 (24.8%) with prostate-only RT, including or not including, the seminal vesicles (PORT ± SV). 45 patients (30.2%) developed peak grade ≥ 2 diarrhea during treatment. At univariate analysis, IC-V 15 and IC-V 30 , but not IC-V 45 , were correlated to the endpoint; at multivariate analysis, only IC-V 15 (p = 0.047) along with peak acute proctitis (p = 0.041) was independently correlated with the endpoint. Conclusion: these data provide a novel and prostate treatment-specific ''upper limit'' DVH for IC. (orig.)

Dosimetric comparison of interactive planned and dynamic dose calculated prostate seed brachytherapy.

Science.gov (United States)

Meijer, Gert J; van den Berg, Hetty A; Hurkmans, Coen W; Stijns, Pascal E; Weterings, Jan H

2006-09-01

To compare the dosimetrical results of an interactive planning procedure and a procedure based on dynamic dose calculation for permanent prostate brachytherapy. Between 6/2000 and 11/2005, 510 patients underwent (125)I implants for T1-T2 prostate cancer. Before 4/2003, 187 patients were treated using an interactive technique that included needle updating. After that period, 323 patients were treated with a more refined dynamic technique that included constant updating of the deposited seed position. The comparison is based on postimplant dose - volume parameters such as the V(100) and d(90) for the target, V(100)(r) for the rectum and d(10)(u) for the urethra. Furthermore, the target volume ratios (TVR identical with V(100)(body)/V(100)), and the homogeneity indices (HI identical with [V(100)-V(150)]/V(100)) were calculated as additional quality parameters. The dose outside the target volume was significantly reduced, the V(100)(r) decreased from 1.4 cm(3) for the interactive technique to 0.6 cm(3) for the dynamic technique. Similarly the mean TVR reduced from 1.66 to 1.44. In addition, the mean V(100) increased from 92% for the interactive procedure to 95% for the dynamic procedure. More importantly, the percentage of patients with a V(100) < 80% reduced from 5% to 1%. A slight decline was observed with regard to the d(10)(u) (136% vs. 140%) and the HI (0.58 vs. 0.51). The dynamic implant procedure resulted in improved implants. Almost ideal dose coverage was achieved, while minimizing the dose outside the prostate.

Dosimetric comparison of field in field intensity-modulated radiotherapy technique with conformal radiotherapy techniques in breast cancer

International Nuclear Information System (INIS)

Ercan, T.; Alco, G.; Zengin, F.; Atilla, S.; Dincer, M.; Igdem, S.; Okkan, S.

2010-01-01

The aim of this study was to be able to implement the field-in-field intensity-modulated radiotherapy (FiF) technique in our daily practice for breast radiotherapy. To do this, we performed a dosimetric comparison. Treatment plans were produced for 20 consecutive patients. FiF plans and conformal radiotherapy (CRT) plans were compared for doses in the planning target volume (PTV), the dose homogeneity index (DHI), doses in irradiated soft tissue outside the target volume (SST), ipsilateral lung and heart doses for left breast irradiation, and the monitor unit counts (MU) required for treatment. Averaged values were compared using Student's t-test. With FiF, the DHI is improved 7.0% and 5.7%, respectively (P<0.0001) over the bilateral and lateral wedge CRT techniques. When the targeted volumes received 105% and 110% of the prescribed dose in the PTV were compared, significant decreases are found with the FiF technique. With the 105% dose, the SST, heart, and ipsilateral lung doses and the MU counts were also significantly lower with the FiF technique. The FiF technique, compared to CRT, for breast radiotherapy enables significantly better dose distribution in the PTV. Significant differences are also found for soft tissue volume, the ipsilateral lung dose, and the heart dose. Considering the decreased MUs needed for treatment, the FiF technique is preferred over tangential CRT. (author)

Dosimetric comparison of intensity-modulated, conformal, and four-field pelvic radiotherapy boost plans for gynecologic cancer: a retrospective planning study

International Nuclear Information System (INIS)

Chan, Philip; Yeo, Inhwan; Perkins, Gregory; Fyles, Anthony; Milosevic, Michael

2006-01-01

To evaluate intensity-modulated radiation therapy (IMRT) as an alternative to conformal radiotherapy (CRT) or 4-field box boost (4FB) in women with gynecologic malignancies who are unsuitable for brachytherapy for technical or medical reasons. Dosimetric and toxicity information was analyzed for 12 patients with cervical (8), endometrial (2) or vaginal (2) cancer previously treated with external beam pelvic radiotherapy and a CRT boost. Optimized IMRT boost treatment plans were then developed for each of the 12 patients and compared to CRT and 4FB plans. The plans were compared in terms of dose conformality and critical normal tissue avoidance. The median planning target volume (PTV) was 151 cm 3 (range 58–512 cm 3 ). The median overlap of the contoured rectum with the PTV was 15 (1–56) %, and 11 (4–35) % for the bladder. Two of the 12 patients, both with large PTVs and large overlap of the contoured rectum and PTV, developed grade 3 rectal bleeding. The dose conformity was significantly improved with IMRT over CRT and 4FB (p ≤ 0.001 for both). IMRT also yielded an overall improvement in the rectal and bladder dose-volume distributions relative to CRT and 4FB. The volume of rectum that received the highest doses (>66% of the prescription) was reduced by 22% (p < 0.001) with IMRT relative to 4FB, and the bladder volume was reduced by 19% (p < 0.001). This was at the expense of an increase in the volume of these organs receiving doses in the lowest range (<33%). These results indicate that IMRT can improve target coverage and reduce dose to critical structures in gynecologic patients receiving an external beam radiotherapy boost. This dosimetric advantage will be integrated with other patient and treatment-specific factors, particularly internal tumor movement during fractionated radiotherapy, in the context of a future image-guided radiation therapy study

A dosimetric comparison of IORT techniques in limited-stage breast cancer

International Nuclear Information System (INIS)

Nairz, O.; Deutschmann, H.; Kopp, M.; Wurstbauer, K.; Kametriser, G.; Fastner, G.; Merz, F.; Sedlmayer, F.; Reitsamer, R.; Menzel, C.

2006-01-01

Background and purpose: for intraoperative radiotherapy (IORT) during breast-conserving treatment four different techniques have been addressed: interstitial brachytherapy, an inflatable balloon with a central high-dose-rate source (MammoSite), a miniature orthovolt system (Intrabeam), and linac-based electron radiotherapy (IOERT). The dosimetric properties of these methods are compared. Material and methods: planning target volumes (PTVs) of the same size but of different shapes are assumed, corresponding to the technique's specific situs. Dose distributions for the PTVs and for surrounding tissues are demonstrated by dose-volume histograms and a list of physical parameters. A dose inhomogeneity index (DII) is introduced to describe the deviation of a delivered from the prescribed dose, reaching its minimal value 0 in case of perfect homogeneity. Results: in terms of DII, IOERT reaches the lowest value followed by the MammoSite, the Intrabeam and interstitial implants. The surrounding tissues receive the smallest average dose with IOERT, closely followed by the orthovolt system. Conclusion: when comparing simplified geometric figures, IOERT delivers the most homogeneous dose distributions. However, in clinical reality PTVs often present asymmetric shapes instead of ideal geometries. Due to a strictly centric dose fall-off, any system with a round central applicator will have technical limits. During IOERT margin-directed applicator guidance is possible and interstitial brachytherapy allows for polygonal dose shaping. These techniques seem to be superior for asymmetric PTV irradiation. (orig.)

Single-arc volumetric-modulated arc therapy (sVMAT) as adjuvant treatment for gastric cancer: Dosimetric comparisons with three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT)

International Nuclear Information System (INIS)

Wang, Xin; Li, Guangjun; Zhang, Yingjie; Bai, Sen; Xu, Feng; Wei, Yuquan; Gong, Youling

2013-01-01

To compare the dosimetric differences between the single-arc volumetric-modulated arc therapy (sVMAT), 3-dimensional conformal radiotherapy (3D-CRT), and intensity-modulated radiotherapy (IMRT) techniques in treatment planning for gastric cancer as adjuvant radiotherapy. Twelve patients were retrospectively analyzed. In each patient's case, the parameters were compared based on the dose-volume histogram (DVH) of the sVMAT, 3D-CRT, and IMRT plans, respectively. Three techniques showed similar target dose coverage. The maximum and mean doses of the target were significantly higher in the sVMAT plans than that in 3D-CRT plans and in the 3D-CRT/IMRT plans, respectively, but these differences were clinically acceptable. The IMRT and sVMAT plans successfully achieved better target dose conformity, reduced the V 20/30 , and mean dose of the left kidney, as well as the V 20/30 of the liver, compared with the 3D-CRT plans. And the sVMAT technique reduced the V 20 of the liver much significantly. Although the maximum dose of the spinal cord were much higher in the IMRT and sVMAT plans, respectively (mean 36.4 vs 39.5 and 40.6 Gy), these data were still under the constraints. Not much difference was found in the analysis of the parameters of the right kidney, intestine, and heart. The IMRT and sVMAT plans achieved similar dose distribution to the target, but superior to the 3D-CRT plans, in adjuvant radiotherapy for gastric cancer. The sVMAT technique improved the dose sparings of the left kidney and liver, compared with the 3D-CRT technique, but showed few dosimetric advantages over the IMRT technique. Studies are warranted to evaluate the clinical benefits of the VMAT treatment for patients with gastric cancer after surgery in the future

Dosimetric predictors of hypothyroidism in oropharyngeal cancer patients treated with intensity-modulated radiation therapy

International Nuclear Information System (INIS)

Chyan, Arthur; Chen, Josephine; Shugard, Erin; Lambert, Louise; Quivey, Jeanne M; Yom, Sue S

2014-01-01

Radiation to the neck has long been associated with an elevated risk of hypothyroidism development. The goal of the present work is to define dosimetric predictors of hypothyroidism in oropharyngeal cancer (OPC) patients treated with intensity-modulated radiation therapy. Data for 123 patients, with a median follow up of 4.6 years, were retrospectively analyzed. Patients with elevated thyroid-stimulating hormone levels or with a clinical diagnosis were categorized as hypothyroid. Patient demographic parameters, thyroid volume, mean thyroid dose, the percent of thyroid volume receiving minimum specified dose levels (VxxGy), and the absolute thyroid volume spared from specified dose levels (VSxxGy) were analyzed. Normal-tissue complication probability (NTCP) was also calculated using several recently published models. Thyroid volume and many radiation dosimetric parameters were statistically different in the hypothyroid group. For the patients with initial thyroid volumes of 8 cc or greater, several dosimetric parameters were found to define subgroups at statistically significant lower risk of developing hypothyroidism. Patients with VS45 Gy of at least 3 cc, VS50 Gy at least 5 cc, VS50 Gy at least 6 cc, V50 Gy below 45%, V50 Gy below 55%, or mean thyroid dose below 49 Gy had a 28-38% estimated risk of hypothyroidism at 3 years compared to a 55% risk for the entire study group. Patients with a NTCP of less than 0.75 or 0.8, calculated using recently published models, were also observed to have a lower risk of developing hypothyroidism. Based on long-term follow up data for OPC patients treated with IMRT, we recommend plan optimization objectives to reduce the volume of thyroid receiving over 45 Gy to significantly decrease the risk of developing hypothyroidism. The online version of this article (doi:10.1186/s13014-014-0269-4) contains supplementary material, which is available to authorized users

Dosimetric comparison between helical tomotherapy and intensity-modulated radiation therapy plans for non-small cell lung cancer.

Science.gov (United States)

Meng, Ling-Ling; Feng, Lin-Chun; Wang, Yun-Lai; Dai, Xiang-Kun; Xie, Chuan-Bin

2011-06-01

Helical tomotherapy (HT) is a new image-guided intensity-modulated radiation therapy (IMRT) technique. It is reported that HT plan for non-small-cell lung cancer (NSCLC) can give better dose uniformity, dose gradients, and protection for the lung than IMRT plan. We compared the dosimetric characteristics of HT for NSCLC with those of conventional IMRT to observe the superiority of HT. There was a comparative case series comprising 10 patients with NSCLC. Computed tomographic (CT) images of delineated targets were transferred to the PrecisePlan planning system (IMRT) and Tomo planning system (HT). The prescription doses were 70 Gy/33F for the gross tumor volume (GTV) and the visible lymph nodes (GTVnd), and 60 Gy/33F for the clinical target volume (CTV) and the clinical target volume of the visible lymph nodes (CTVnd). The dose restrictions for organs at risk were as follows: the maximum dose to spinal cord ≤ 45 Gy, V20 to the total lungs 0.05). The maximum doses to the spinal cord, heart, esophagus and trachea in the HT plan were lower than those in the IMRT plan, but the differences were not statistically significant. The HT plan provids better dose uniformity, dose gradients, and protection for the organs at risk. It can reduce the high-dose radiation volume for lung and the MLD, but may deliver a larger lung volume of low-dose radiation.

ESR dosimetric properties of some biomineral materials

International Nuclear Information System (INIS)

Hassan, Gamal M.; Sharaf, M.A.

2005-01-01

Dosimetric properties of g-irradiated modern coral and bioactive glass (Bio-G) samples analyzed with electron spin resonance (ESR) have been separately reported (Hassan et al., 2004; Sharaf and Hassan, 2004) and compared with alanine. These are combined here to allow a three-way comparison between these materials

ESR dosimetric properties of some biomineral materials

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Hassan, Gamal M. [Department of Ionizing Radiation Metrology, National Institute for Standards (NIS), Tersa Street, El-Haram, El-Giza, P.O. Box 136 Giza, El-Giza (Egypt)]. E-mail: gamalhassan65@hotmail.com; Sharaf, M.A. [Department of Ionizing Radiation Metrology, National Institute for Standards (NIS), Tersa Street, El-Haram, El-Giza, P.O. Box 136 Giza, El-Giza (Egypt)

2005-02-01

Dosimetric properties of g-irradiated modern coral and bioactive glass (Bio-G) samples analyzed with electron spin resonance (ESR) have been separately reported (Hassan et al., 2004; Sharaf and Hassan, 2004) and compared with alanine. These are combined here to allow a three-way comparison between these materials.

IPIP: A new approach to inverse planning for HDR brachytherapy by directly optimizing dosimetric indices

International Nuclear Information System (INIS)

Siauw, Timmy; Cunha, Adam; Atamtuerk, Alper; Hsu, I-Chow; Pouliot, Jean; Goldberg, Ken

2011-01-01

Purpose: Many planning methods for high dose rate (HDR) brachytherapy require an iterative approach. A set of computational parameters are hypothesized that will give a dose plan that meets dosimetric criteria. A dose plan is computed using these parameters, and if any dosimetric criteria are not met, the process is iterated until a suitable dose plan is found. In this way, the dose distribution is controlled by abstract parameters. The purpose of this study is to develop a new approach for HDR brachytherapy by directly optimizing the dose distribution based on dosimetric criteria. Methods: The authors developed inverse planning by integer program (IPIP), an optimization model for computing HDR brachytherapy dose plans and a fast heuristic for it. They used their heuristic to compute dose plans for 20 anonymized prostate cancer image data sets from patients previously treated at their clinic database. Dosimetry was evaluated and compared to dosimetric criteria. Results: Dose plans computed from IPIP satisfied all given dosimetric criteria for the target and healthy tissue after a single iteration. The average target coverage was 95%. The average computation time for IPIP was 30.1 s on an Intel(R) Core TM 2 Duo CPU 1.67 GHz processor with 3 Gib RAM. Conclusions: IPIP is an HDR brachytherapy planning system that directly incorporates dosimetric criteria. The authors have demonstrated that IPIP has clinically acceptable performance for the prostate cases and dosimetric criteria used in this study, in both dosimetry and runtime. Further study is required to determine if IPIP performs well for a more general group of patients and dosimetric criteria, including other cancer sites such as GYN.

Dosimetric rationale and early experience at UFPTI of thoracic proton therapy and chemotherapy in limited-stage small cell lung cancer

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Colaco, Rovel J.; Huh, Soon; Nichols, Romaine; Morris, Christopher G.; Flampouri, Stella; Li, Zuofeng; Hoppe, Bradford S. [Univ. of Florida Proton Therapy Inst., Jacksonville (United States)], e-mail: bhoppe@floridaproton.org; D' Agostino, Harry [Dept. of Thoracic Surgery, Univ. of Florida Coll. of Medicine, Gainesville (United States); Pham, Dat C. [Dept. of Hematology and Medical Oncology, Univ. of Florida Coll. of Medicine, Gainesville (United States); Bajwa, Abubakr A. [Dept. of Medicine, Univ. of Florida Coll. of Medicine, Gainesville (United States)

2013-04-15

Background: Concurrent chemoradiotherapy (CRT) is the standard of care in patients with limited-stage small cell lung cancer (SCLC). Treatment with conventional x-ray therapy (XRT) is associated with high toxicity rates, particularly acute grade 3+ esophagitis and pneumonitis. We present outcomes for the first known series of limited-stage SCLC patients treated with proton therapy and a dosimetric comparison of lung and esophageal doses with intensity-modulated radiation therapy (IMRT). Material and methods: Six patients were treated; five concurrently and one sequentially. Five patients received 60-66 CGE in 30-34 fractions once daily and one patient received 45 CGE in 30 fractions twice daily. All six patients received prophylactic cranial irradiation. Common Terminology Criteria for Adverse Events, v3.0, was used to grade toxicity. IMRT plans were also generated and compared with proton plans. Results: The median follow-up was 12.0 months. The one-year overall and progression-free survival rates were 83% and 66%, respectively. There were no cases of acute grade 3+ esophagitis or acute grade 2+ pneumonitis, and no other acute grade 3+ non-hematological toxicities were seen. One patient with a history of pulmonary fibrosis and atrial fibrillation developed worsening symptoms four months after treatment requiring oxygen. Three patients died; two of progressive disease and one after a fall. The latter patient was disease-free at 36 months after treatment. Another patient recurred and is alive, while two patients remain disease-free at 12 months of follow-up. Proton therapy proved superior to IMRT across all esophageal and lung dose volume points. Conclusion. In this small series of SCLC patients treated with proton therapy with radical intent, treatment was well tolerated with no cases of acute grade 3+ esophagitis or acute grade 2+ pneumonitis. Dosimetric comparison showed better sparing of lung and esophagus with proton therapy. Proton therapy merits further

Dosimetric rationale and early experience at UFPTI of thoracic proton therapy and chemotherapy in limited-stage small cell lung cancer

International Nuclear Information System (INIS)

Colaco, Rovel J.; Huh, Soon; Nichols, Romaine; Morris, Christopher G.; Flampouri, Stella; Li, Zuofeng; Hoppe, Bradford S.; D'Agostino, Harry; Pham, Dat C.; Bajwa, Abubakr A.

2013-01-01

Background: Concurrent chemoradiotherapy (CRT) is the standard of care in patients with limited-stage small cell lung cancer (SCLC). Treatment with conventional x-ray therapy (XRT) is associated with high toxicity rates, particularly acute grade 3+ esophagitis and pneumonitis. We present outcomes for the first known series of limited-stage SCLC patients treated with proton therapy and a dosimetric comparison of lung and esophageal doses with intensity-modulated radiation therapy (IMRT). Material and methods: Six patients were treated; five concurrently and one sequentially. Five patients received 60-66 CGE in 30-34 fractions once daily and one patient received 45 CGE in 30 fractions twice daily. All six patients received prophylactic cranial irradiation. Common Terminology Criteria for Adverse Events, v3.0, was used to grade toxicity. IMRT plans were also generated and compared with proton plans. Results: The median follow-up was 12.0 months. The one-year overall and progression-free survival rates were 83% and 66%, respectively. There were no cases of acute grade 3+ esophagitis or acute grade 2+ pneumonitis, and no other acute grade 3+ non-hematological toxicities were seen. One patient with a history of pulmonary fibrosis and atrial fibrillation developed worsening symptoms four months after treatment requiring oxygen. Three patients died; two of progressive disease and one after a fall. The latter patient was disease-free at 36 months after treatment. Another patient recurred and is alive, while two patients remain disease-free at 12 months of follow-up. Proton therapy proved superior to IMRT across all esophageal and lung dose volume points. Conclusion. In this small series of SCLC patients treated with proton therapy with radical intent, treatment was well tolerated with no cases of acute grade 3+ esophagitis or acute grade 2+ pneumonitis. Dosimetric comparison showed better sparing of lung and esophagus with proton therapy. Proton therapy merits further

Dosimetric comparison of volumetric modulated arc therapy (VMAT), DMlC (Dynamic IMRT), and 3DCRT in left breast cancer after breast conserving surgery receiving left breast irradiation

International Nuclear Information System (INIS)

Pratibha, Bauskar; Vibhay, Pareek; Rajendra, Bhalavat; Chandra, Manish

2016-01-01

Previous studies have demonstrated that the risk of ischemic heart disease is increased as a result of exposure to ionizing radiation in women treated for breast cancer. Alternative radiation techniques, such as dynamic intensity-modulated radiation therapy (DMLC), volumetric-modulated arc therapy (VMAT), have been shown to improve dosimetric parameters of the heart and substructures. However, these techniques have not been compared with each other to potentially guide treatment decisions. Volumetric modulated arc therapy (VMAT) is a novel extension of conventional intensity-modulated radiotherapy (c-IMRT), in which an optimized three dimensional dose distribution may be delivered in a single gantry rotation. VMAT is the predecessor to Rapid-Arc (Varian Medical System). This study uses VMAT, DMLC and 3DCRT to compare target volume coverage and doses to organs at risk (OARs), especially lung and heart doses, using these three techniques in whole breast irradiation after breast conserving surgery in left breast cancer cases

Dosimetric and geometric evaluation of a novel stereotactic radiotherapy device for breast cancer: The GammaPod Trade-Mark-Sign

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Mutaf, Yildirim D.; Yi, Byong Yong; Prado, Karl; D' Souza, Warren D.; Regine, William F.; Feigenberg, Steven J. [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201 (United States); Zhang Jin [Xcision Medical Systems, Columbia, Maryland 21045 (United States); Yu, Cedric X. [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201 and Xcision Medical Systems, Columbia, Maryland 21045 (United States)

2013-04-15

Purpose: A dedicated stereotactic gamma irradiation device, the GammaPod Trade-Mark-Sign from Xcision Medical Systems, was developed specifically to treat small breast cancers. This study presents the first evaluation of dosimetric and geometric characteristics from the initial prototype installed at University of Maryland Radiation Oncology Department. Methods: The GammaPod Trade-Mark-Sign stereotactic radiotherapy device is an assembly of a hemi-spherical source carrier containing 36 {sup 60}Co sources, a tungsten collimator, a dynamically controlled patient support table, and the breast immobilization system which also functions as a stereotactic frame. The source carrier contains the sources in six columns spaced longitudinally at 60 Degree-Sign intervals and it rotates together with the variable-size collimator to form 36 noncoplanar, concentric arcs focused at the isocenter. The patient support table enables motion in three dimensions to position the patient tumor at the focal point of the irradiation. The table moves continuously in three cardinal dimensions during treatment to provide dynamic shaping of the dose distribution. The breast is immobilized using a breast cup applying a small negative pressure, where the immobilization cup is embedded with fiducials also functioning as the stereotactic frame for the breast. Geometric and dosimetric evaluations of the system as well as a protocol for absorbed dose calibration are provided. Dosimetric verifications of dynamically delivered patient plans are performed for seven patients using radiochromic films in hypothetical preop, postop, and target-in-target treatment scenarios. Results: Loaded with 36 {sup 60}Co sources with cumulative activity of 4320 Ci, the prototype GammaPod Trade-Mark-Sign unit delivers 5.31 Gy/min at the isocenter using the largest 2.5 cm diameter collimator. Due to the noncoplanar beam arrangement and dynamic dose shaping features, the GammaPod Trade-Mark-Sign device is found to deliver

Dosimetric predictors of radiation-induced pericardial effusion in esophageal cancer

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Ogino, Ichiro; Watanabe, Shigenobu [Yokohama City University Medical Center, Department of Radiation Oncology, Minami-ku, Yokohama, Kanagawa-prefecture (Japan); Sakamaki, Kentaro [Yokohama City University, Department of Biostatistics, Yokohama City University, Yokohama (Japan); Ogino, Yuka [Tokyo Institute of Technology, Department of Systems and Control Engineering, Tokyo (Japan); Kunisaki, Chikara [Yokohama City University Medical Center, Department of Surgery, Gastroenterological Center, Yokohama (Japan); Kimura, Kazuo [Yokohama City University Medical Center, Division of Cardiology, Yokohama (Japan)

2017-07-15

To evaluate the dose-volume parameters of the pericardium and heart in order to reduce the risk of radiation-induced pericardial effusion (PE) and symptomatic PE (SPE) in esophageal cancer patients treated with concurrent chemoradiotherapy. In 86 of 303 esophageal cancer patients, follow-up CT was obtained at least 24 months after concurrent chemoradiotherapy. Correlations between clinical factors, including risk factors for cardiac disease, dosimetric factors, and the incidence of PE and SPE after radiotherapy were analyzed using Cox proportional hazard regression analysis. Significant dosimetric factors with the highest hazard ratios were investigated using zones separated according to their distance from esophagus. PE developed in 49 patients. Univariate analysis showed the mean heart dose, heart V{sub 5}-V{sub 55}, mean pericardium dose, and pericardium V{sub 5}-V{sub 50} to all significantly affect the incidence of PE. Additionally, body surface area was correlated with the incidence of PE in multivariate analysis. Grade 3 and 4 SPE developed in 5 patients. The pericardium V{sub 50} and pericardium D{sub 10} significantly affected the incidence of SPE. The pericardium V{sub 50} in patients with SPE ranged from 17.1 to 21.7%. Factors affecting the incidence of SPE were the V{sub 50} of the pericardium zones within 3 cm and 4 cm of the esophagus. A wide range of radiation doses to the heart and pericardium were related to the incidence of PE. A pericardium V{sub 50} ≤ 17% is important to avoid symptomatic PE in esophageal cancer patients treated with concurrent chemoradiotherapy. (orig.) [German] Beurteilung der Dosis-Volumen-Parameter fuer Perikard und Herz zur Risikoreduzierung eines strahleninduzierten Perikardergusses (PE) und eines symptomatischen PE (SPE) bei mit kombinierter Strahlenchemotherapie behandelten Speiseroehrenkrebspatienten. Bei 86 von 303 Speiseroehrenkrebspatienten wurde mindestens 24 Monate nach der Strahlenchemotherapie ein Kontroll

Dosimetric comparison of intensity modulated radiosurgery with dynamic conformal arc radiosurgery for small cranial lesions

Directory of Open Access Journals (Sweden)

Juan F Calvo-Ortega

2016-01-01

Conclusions: We have shown that IMRS provides the dosimetric advantages compared with DCARS. Based on the dosimetric findings in this study, fixed gantry IMRS technique can be adopted as a standard procedure for cranial SRS when micro-MLC technology is not available on the linear accelerator.

Neurovascular bundle–sparing radiotherapy for prostate cancer using MRI-CT registration: A dosimetric feasibility study

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Cassidy, R.J., E-mail: richardjcassidy@emory.edu [Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA (United States); Yang, X.; Liu, T.; Thomas, M. [Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA (United States); Nour, S.G. [Department of Radiology, Emory University, Atlanta, GA (United States); Jani, A.B. [Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA (United States)

2016-01-01

Purpose: Sexual dysfunction after radiotherapy for prostate cancer remains an important late adverse toxicity. The neurovascular bundles (NVB) that lie posterolaterally to the prostate are typically spared during prostatectomy, but in traditional radiotherapy planning they are not contoured as an organ-at-risk with dose constraints. Our goal was to determine the dosimetric feasibility of “NVB-sparing” prostate radiotherapy while still delivering adequate dose to the prostate. Methods: Twenty-five consecutive patients with prostate cancer (with no extraprostatic disease on pelvic magnetic resonance imaging [MRI]) who that were treated with external beam radiotherapy, with the same primary planning target volume margins, to a dose of 79.2 Gy were evaluated. Pelvic MRI and simulation computed tomography scans were registered using dedicated software to allow for bilateral NVB target delineation on T2-weighted MRI. A volumetric modulated arc therapy plan was generated using the NVB bilaterally with 2 mm margin as an organ to spare and compared to the patient’s previously delivered plan. Dose-volume histogram endpoints for NVB, rectum, bladder, and planning target volume 79.2 were compared between the 2 plans using a 2-tailed paired t-test. Results: The V70 for the NVB was significantly lower on the NVB-sparing plan (p <0.01), while rectum and bladder endpoints were similar. Target V100% was similar but V{sub 105%} was higher for the NVB-sparing plans (p <0.01). Conclusions: “NVB-sparing” radiotherapy is dosimetrically feasible using CT-MRI registration, and for volumetric modulated arc therapy technology — target coverage is acceptable without increased dose to other normal structures, but with higher target dose inhomogeneity. The clinical impact of “NVB-sparing” radiotherapy is currently under study at our institution.

SU-E-T-123: Dosimetric Comparison Between Portrait and Landscape Orientations in Radiochromic Film Dosimetry

International Nuclear Information System (INIS)

Kakinohana, Y; Toita, T; Kasuya, G; Ariga, T; Heianna, J; Murayama, S

2014-01-01

Purpose: To compare the dosimetric properties of radiochromic films with different orientation. Methods: A sheet of EBT3 film was cut into eight pieces with the following sizes: 15×15 cm2 (one piece), 5x15 cm 2 (two) and 4×5 cm 2 (five). A set of two EBT3 sheets was used at each dose level. Two sets were used changing the delivered doses (1 and 2 Gy). The 5×15 cm 2 pieces were rotated by 90 degrees in relation to each other, such that one had landscape orientation and the other had portrait orientation. All 5×15 cm2 pieces were irradiated with their long side aligned with the x-axis of the radiation field. The 15×15 cm 2 pieces were irradiated rotated at 90 degrees to each other. Five pieces, (a total of ten from two sheets) were used to obtain a calibration curve. The irradiated films were scanned using an Epson ES-2200 scanner and were analyzed using ImageJ software. In this study, no correction was applied for the nonuniform scanner signal that is evident in the direction of the scanner lamp. Each film piece was scanned both in portrait and landscape orientations. Dosimetric comparisons of the beam profiles were made in terms of the film orientations (portrait and landscape) and scanner bed directions (perpendicular and parallel to the scanner movement). Results: In general, portrait orientation exhibited higher noise than landscape and was adversely affected to a great extent by the nonuniformity in the direction of the scanner lamp. A significant difference in the measured field widths between the perpendicular and parallel directions was found for both orientations. Conclusion: Without correction for the nonuniform scanner signal in the direction of the scanner lamp, a landscape orientation is preferable. A more detailed investigation is planned to evaluate quantitatively the effect of orientation on the dosimetric properties of a film

SU-E-T-123: Dosimetric Comparison Between Portrait and Landscape Orientations in Radiochromic Film Dosimetry

Energy Technology Data Exchange (ETDEWEB)

Kakinohana, Y [University of the Ryukyus, Okinawa (Japan); Toita, T; Kasuya, G; Ariga, T; Heianna, J; Murayama, S [University of the Ryukyus, Nishihara-cho, Okinawa (Japan)

2014-06-01

Purpose: To compare the dosimetric properties of radiochromic films with different orientation. Methods: A sheet of EBT3 film was cut into eight pieces with the following sizes: 15×15 cm2 (one piece), 5x15 cm{sup 2} (two) and 4×5 cm{sup 2} (five). A set of two EBT3 sheets was used at each dose level. Two sets were used changing the delivered doses (1 and 2 Gy). The 5×15 cm{sup 2} pieces were rotated by 90 degrees in relation to each other, such that one had landscape orientation and the other had portrait orientation. All 5×15 cm2 pieces were irradiated with their long side aligned with the x-axis of the radiation field. The 15×15 cm{sup 2} pieces were irradiated rotated at 90 degrees to each other. Five pieces, (a total of ten from two sheets) were used to obtain a calibration curve. The irradiated films were scanned using an Epson ES-2200 scanner and were analyzed using ImageJ software. In this study, no correction was applied for the nonuniform scanner signal that is evident in the direction of the scanner lamp. Each film piece was scanned both in portrait and landscape orientations. Dosimetric comparisons of the beam profiles were made in terms of the film orientations (portrait and landscape) and scanner bed directions (perpendicular and parallel to the scanner movement). Results: In general, portrait orientation exhibited higher noise than landscape and was adversely affected to a great extent by the nonuniformity in the direction of the scanner lamp. A significant difference in the measured field widths between the perpendicular and parallel directions was found for both orientations. Conclusion: Without correction for the nonuniform scanner signal in the direction of the scanner lamp, a landscape orientation is preferable. A more detailed investigation is planned to evaluate quantitatively the effect of orientation on the dosimetric properties of a film.

Large planning target volume in whole abdomen radiation therapy in ovarian cancers - a comparison between volumetric arc and fixed beam based intensity modulation in ovarian cancers: a comparison between volumetric arc and fixed beam based intensity modulation

International Nuclear Information System (INIS)

Krishnan, Jayapalan; Rao, Suresh; Hedge, Sanath; Shambhavi

2013-01-01

Aim of this study is to assess dosimetric characteristics of multiple iso-centre volumetric-modulated arc therapy for the treatment of a large PTV in whole abdomen and ovarian cancers and in comparison with IMRT. Two patients with Epithelial Ovarian Cancer (EOC) underwent CT-simulation in supine position with vacuum cushion and acquired CT-image with 3 mm slice thickness. IMRT and VMAT plans were generated with multiple isocenter using Eclipse Planning System (V10.0.39) for (6 MV photon) Varian UNIQUE Performance Linac equipped with a Millennium-120 MLC and optimised with Progressive Resolution optimizer (PRO3) for prescription 36 Gy to the whole abdomen (PTV W AR) and 45 Gy with daily fraction of 1.8 Gy to the pelvis and pelvic nodes (PTV P elvis) with Simultaneous Integrated Boost and calculated with AAA algorithm in 2.5 mm grid resolution. Mean, V 95% , V 90% , V 107% and uniformity number (Uniformity was defined as US-95%=D5%-D95%/D mean ) was calculated for Planning Target Volumes (PTVs). Organs at Risk (OAR's) were analysed statistically in terms of dose and volume. MU and delivery time were compared. Pre-treatment quality assurance was scored with Gamma Agreement Index (GAl) with 3% and 3 mm thresholds with EPID as well as corresponding Dynalog files were generated and analysed. Feasibility and deliverability of VMAT plans showed to be a solution for the treatment planning and delivery for a large PTV volume (PTV-WAR) treatments, surrounded by critical structures such as liver, spinal canal, and kidneys, offering good dosimetric features with significant logistic improvements compared to IMRT. VMAT combines the advantages of faster delivery and lower number of monitor units (MU). It would help to reduce potential risk of secondary malignancy. VMAT(RapidArc) showed to be a solution to WAR treatments offering good dosimetric features with significant logistic improvements compared to IMRT

Weekly Volume and Dosimetric Changes During Chemoradiotherapy With Intensity-Modulated Radiation Therapy for Head and Neck Cancer: A Prospective Observational Study

Energy Technology Data Exchange (ETDEWEB)

Bhide, Shreerang A [Institute of Cancer Research, 237 Fulham Road, London SW6 6JB (United Kingdom); Head and Neck Unit, Royal Marsden NHS Foundation Trust Hospital, London SW3 6JJ (United Kingdom); Davies, Mark; Burke, Kevin; McNair, Helen A; Hansen, Vibeke [Department of Radiation Oncology, Royal Marsden NHS Foundation Trust Hospital, London and Sutton (United Kingdom); Barbachano, Y [Department of Statistics, Royal Marsden NHS Foundation Trust Hospital, London and Sutton (United Kingdom); El-Hariry, I A [Head and Neck Unit, Royal Marsden NHS Foundation Trust Hospital, London SW3 6JJ (United Kingdom); Newbold, Kate [Department of Radiation Oncology, Royal Marsden NHS Foundation Trust Hospital, London and Sutton (United Kingdom); Harrington, Kevin J [Institute of Cancer Research, 237 Fulham Road, London SW6 6JB (United Kingdom); Head and Neck Unit, Royal Marsden NHS Foundation Trust Hospital, London SW3 6JJ (United Kingdom); Nutting, Christopher M., E-mail: chris.nutting@rmh.nhs.u [Head and Neck Unit, Royal Marsden NHS Foundation Trust Hospital, London SW3 6JJ (United Kingdom)

2010-04-15

Purpose: The aim of this study was to investigate prospectively the weekly volume changes in the target volumes and organs at risk and the resulting dosimetric changes during induction chemotherapy followed by chemoradiotherapy with intensity-modulated radiation therapy (C-IMRT) for head-and-neck cancer patients. Methods and Materials: Patients receiving C-IMRT for head-and-neck cancer had repeat CT scans at weeks 2, 3, 4, and 5 during radiotherapy. The volume changes of clinical target volume 1 (CTV1) and CTV2 and the resulting dosimetric changes to planning target volume 1 (PTV1) and PTV2 and the organs at risk were measured. Results: The most significant volume differences were seen at week 2 for CTV1 and CTV2. The reductions in the volumes of CTV1 and CTV2 at week 2 were 3.2% and 10%, respectively (p = 0.003 and p < 0.001). The volume changes resulted in a significant reduction in the minimum dose to PTV1 and PTV2 (2 Gy, p = 0.002, and 3.9 Gy, p = 0.03, respectively) and an increased dose range across PTV1 and PTV2 (2.5 Gy, p < 0.001, and 5.1 Gy, p = 0.008, respectively). There was a 15% reduction in the parotid volumes by week 2 (p < 0.001) and 31% by week 4 (p < 0.001). There was a statistically significant increase in the mean dose to the ipsilateral parotid only at week 4 (2.7 Gy, p = 0.006). The parotid glands shifted medially by an average of 2.3 mm (p < 0.001) by week 4. Conclusion: The most significant volumetric changes and dosimetric alterations in the tumor volumes and organs at risk during a course of C-IMRT occur by week 2 of radiotherapy. Further adaptive radiotherapy with replanning, if appropriate, is recommended.

Use of a dosimetric system using a SMT phototransistor in the measurement for some dosimetric parameters in conventional radiotherapy

International Nuclear Information System (INIS)

Silva, J.O. da; Magalhaes, C.M.S. de; Santos, L.A.P.

2008-01-01

For monitoring the delivered dose in the patient undergoing a cancer treatment with high-energy ionizing radiation beams is necessary to use appropriate dosimeters for the beam control quality and if it is possible, to obtain the dose information during the treatment. For this, semiconductor-based devices are used because of their high spatial resolution and to be easy to handle in spite of the ionization chambers. Nowadays the bipolar phototransistors are being proposed as ionizing radiation detectors for presenting, beyond these characteristics, the signal amplification factor (gain). So, the aim of this work is to present the use of a dosimetric system using a SMT phototransistor in the measurement for some dosimetric parameters in conventional radiotherapy: the field factor and the off-axis ratio. The phototransistors readings were compared with ones obtained from a PTW 23343 Markus chamber, under the same conditions. (author)

Comparison and utilization of two dosimetric systems for e-beam industrial irradiation

Energy Technology Data Exchange (ETDEWEB)

Fortes, Marcio Z., E-mail: mzamboti@aceletron.com.b [Aceletron Irradiacao Industrial, Rio de Janeiro, RJ (Brazil). Gerencia Tecnica e Operacoes; Sousa, Fernando N.C. de; Boente, Otavio C., E-mail: fernando.nuno@aceletron.com.b, E-mail: otavio@aceletron.com.b [Aceletron Irradiacao Industrial, Rio de Janeiro, RJ (Brazil). Gerencia de Desenvolvimento de Produtos; Sousa, Nuno R.A., E-mail: engenheiro.nuno.sousa@gmail.co [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Dept. de Engenharia Mecanica

2009-07-01

The utilization of electron linear accelerators (LINAC's) for industrial irradiation of several products like turf, sterilization of medical products, cosmetics, polymers, food, and gems, can only be successful if a reliable dosimetric system is chosen. There are several different available technologies and two were selected for this study. The first one uses alanine dosimeters which can be read with electron spin resonance spectrometers (ESR); the second uses B3 radiochromic dosimeters which are read with a spectrophotometer. This study presents a comparison of both technologies in the dose range of 1 to 80 kGy, taking into account initial cost, precision, reading time, calibration, among others, for a typical 24 hour production run, and for normal operational routines and tests. It is shown that each system has its own advantages and disadvantages, and that both can be used in an e-beam installation. However, for industrial applications it is necessary to optimize the process, so it is presented which dosimeter is used for each routine application. (author)

Improved Dosimetric and Clinical Outcomes With Intensity-Modulated Radiotherapy for Head-and-Neck Cancer of Unknown Primary Origin

International Nuclear Information System (INIS)

Chen, Allen M.; Li Baoqing; Farwell, D. Gregory; Marsano, Joseph; Vijayakumar, Srinivasan; Purdy, James A.

2011-01-01

Purpose: To compare differences in dosimetric, clinical, and quality-of-life endpoints among a cohort of patients treated by intensity-modulated radiotherapy (IMRT) and conventional radiotherapy (CRT) for head-and-neck cancer of unknown primary origin. Methods and Materials: The medical records of 51 patients treated by radiation therapy for squamous cell carcinoma of the head and neck presenting as cervical lymph node metastasis of occult primary origin were reviewed. Twenty-four patients (47%) were treated using CRT, and 27 (53%) were treated using IMRT. The proportions of patients receiving concurrent chemotherapy were 54% and 63%, respectively. Results: The 2-year estimates of overall survival, local-regional control, and disease-specific survival for the entire patient population were 86%, 89%, and84%, respectively. There were no significant differences in any of these endpoints with respect to radiation therapy technique (p > 0.05 for all). Dosimetric analysis revealed that the use of IMRT resulted in significant improvements with respect to mean dose and V30 to the contralateral (spared) parotid gland. In addition, mean doses to the ipsilateral inner and middle ear structures were significantly reduced with IMRT (p < 0.05 for all). The incidence of severe xerostomia in the late setting was 58% and 11% among patients treated by CRT and IMRT, respectively (p < 0.001). The percentages of patients who were G-tube dependent at 6 months after treatment were 42% and 11%, respectively (p < 0.001). Conclusions: IMRT results in significant improvements in the therapeutic ratio among patients treated by radiation therapy for head-and-neck cancer of unknown primary origin.

Dosimetric comparison between RapidArc and fixed gantry intensity modulated radiation therapy in treatment of liver carcinoma

International Nuclear Information System (INIS)

Ma Changsheng; Yin Yong; Liu Tonghai; Chen Jinhu; Sun Tao; Lin Xiutong

2010-01-01

Objective: To compare the dosimetric difference of RapidArc and fixed gantry IMRT for liver carcinoma. Methods: The CT data of 10 liver cancer patients were used to design 3 groups of treatment plan: IMRT plan, single arc RapidArc plan (RA1), and dual arc RapidArc plan (RA2). The planning target volume (PTV) dosimetric distribution, the organs at risk (OAR) dose, the normal tissue dose, mornitor units (MU) and treatment time were compared. Results: The maximum dose of PTV in RA1 and RA2 plans were lower than that of IMRT (Z=-2.0990, -2.666, P 40 of stomach small bowel than IMRT plan, but higher in mean dose of left kidney (Z=-1.988, -2.191, P 5 , V 10 and 15 of healthy tissue in RapidArc plan groups were higher than those in IMRT plan, while the values of V 20 , V 25 and V 30 of healthy tissue in RapidArc plan groups were than those in IMRT plan. The number of computed MU/fraction of Rapid Arc plan was 40% or 46% of IMRT plan and the treatment time was 30% and 40% of IMRT. Conclusions: RapidArc showed improvements in conformity index and healthy tissue sparing with uncompromised target coverage. RapidArc could lead to the less MU and shorter delivery time compared to IMRT. (authors)

Correlation between gamma index passing rate and clinical dosimetric difference for pre-treatment 2D and 3D volumetric modulated arc therapy dosimetric verification.

Science.gov (United States)

Jin, X; Yan, H; Han, C; Zhou, Y; Yi, J; Xie, C

2015-03-01

To investigate comparatively the percentage gamma passing rate (%GP) of two-dimensional (2D) and three-dimensional (3D) pre-treatment volumetric modulated arc therapy (VMAT) dosimetric verification and their correlation and sensitivity with percentage dosimetric errors (%DE). %GP of 2D and 3D pre-treatment VMAT quality assurance (QA) with different acceptance criteria was obtained by ArcCHECK® (Sun Nuclear Corporation, Melbourne, FL) for 20 patients with nasopharyngeal cancer (NPC) and 20 patients with oesophageal cancer. %DE were calculated from planned dose-volume histogram (DVH) and patients' predicted DVH calculated by 3DVH® software (Sun Nuclear Corporation). Correlation and sensitivity between %GP and %DE were investigated using Pearson's correlation coefficient (r) and receiver operating characteristics (ROCs). Relatively higher %DE on some DVH-based metrics were observed for both patients with NPC and oesophageal cancer. Except for 2%/2 mm criterion, the average %GPs for all patients undergoing VMAT were acceptable with average rates of 97.11% ± 1.54% and 97.39% ± 1.37% for 2D and 3D 3%/3 mm criteria, respectively. The number of correlations for 3D was higher than that for 2D (21 vs 8). However, the general correlation was still poor for all the analysed metrics (9 out of 26 for 3D 3%/3 mm criterion). The average area under the curve (AUC) of ROCs was 0.66 ± 0.12 and 0.71 ± 0.21 for 2D and 3D evaluations, respectively. There is a lack of correlation between %GP and %DE for both 2D and 3D pre-treatment VMAT dosimetric evaluation. DVH-based dose metrics evaluation obtained from 3DVH will provide more useful analysis. Correlation and sensitivity of %GP with %DE for VMAT QA were studied for the first time.

Dosimetric properties of the fast neutron therapy beams at TAMVEC

International Nuclear Information System (INIS)

Almond, P.R.; Smith, A.R.; Smathers, J.R.; Otte, V.A.

1975-01-01

In October 1972, M.D. Anderson Hospital and Tumor Institute of the University of Texas System Cancer Center initiated a clinical trial of fast neutron radiotherapy using the cyclotron at Texas A and M University. Initially, the study used neutrons produced by bombarding beryllium with 16 MeV deuterons, but since March, 1973, neutrons from 50 MeV deuterons have been used. The dosimetric properties of the 30 MeV beams have also been measured for comparison with the neutron beams from D-T generators. The three beams are compared in terms of dose rate, skin sparing, depth dose and field flatness. Isodose curves for treatment planning were generated using the decrement line method and compared to curves measured by a computer controlled isodose plotter. This system was also used to measure the isodose curves for wedge fields. Dosimetry checks on various patients were made using silicon diodes as in vivo fast neutron dosimeters

Dosimetric and patient correlates of quality of life after prostate stereotactic ablative radiotherapy

International Nuclear Information System (INIS)

Elias, Evelyn; Helou, Joelle; Zhang, Liying; Cheung, Patrick; Deabreu, Andrea; D’Alimonte, Laura; Sethukavalan, Perakaa; Mamedov, Alexandre; Cardoso, Marlene; Loblaw, Andrew

2014-01-01

Background and purpose: Initial results of Stereotactic Ablative Body Radiotherapy (SABR) in the treatment of localized prostate cancer appear promising however long-term quality of life (QOL) outcomes and dosimetric correlates are necessary. Material and methods: A phase I/II study was performed where low risk prostate cancer patients received SABR 35 Gy in 5 fractions, once weekly. Patient self-reported QOL was measured using the Expanded Prostate Cancer Index Composite (EPIC) at baseline and q6 month up to 5 years. Urinary, bowel and sexual domains were analyzed. A minimally clinical important change (MCIC) was defined as 0.5 ∗ standard deviation of the baseline. Univariate and multivariate logistic regression were used to identify dosimetric predictors of MCIC. Results: 84 patients were included. The median follow-up was 50.8 months (interquartile range [IQR], 44.7–56.3). 17.9%, 26.2% and 37.5% of patients reported worse QOL on follow up in the urinary, bowel and sexual domains respectively. On univariate analysis Rectal V31.8 > 10%, D1cc > 35 Gy were associated with bowel MCIC, penile bulb (PB) V35 > 4%, V20 > 40% with sexual MCIC. Of these factors only rectal D1cc and PB V35 were predictors of worse QOL on multivariate analysis. Conclusions: Long-term single-institution QOL outcomes are encouraging. Rigorous dosimetric constraints are needed to keep bothersome side effects low

SU-E-J-94: Geometric and Dosimetric Evaluation of Deformation Image Registration Algorithms Using Virtual Phantoms Generated From Patients with Lung Cancer

International Nuclear Information System (INIS)

Shen, Z; Greskovich, J; Xia, P; Bzdusek, K

2015-01-01

Purpose: To generate virtual phantoms with clinically relevant deformation and use them to objectively evaluate geometric and dosimetric uncertainties of deformable image registration (DIR) algorithms. Methods: Ten lung cancer patients undergoing adaptive 3DCRT planning were selected. For each patient, a pair of planning CT (pCT) and replanning CT (rCT) were used as the basis for virtual phantom generation. Manually adjusted meshes were created for selected ROIs (e.g. PTV, lungs, spinal cord, esophagus, and heart) on pCT and rCT. The mesh vertices were input into a thin-plate spline algorithm to generate a reference displacement vector field (DVF). The reference DVF was used to deform pCT to generate a simulated replanning CT (srCT) that was closely matched to rCT. Three DIR algorithms (Demons, B-Spline, and intensity-based) were applied to these ten virtual phantoms. The images, ROIs, and doses were mapped from pCT to srCT using the DVFs computed by these three DIRs and compared to those mapped using the reference DVF. Results: The average Dice coefficients for selected ROIs were from 0.85 to 0.96 for Demons, from 0.86 to 0.97 for intensity-based, and from 0.76 to 0.95 for B-Spline. The average Hausdorff distances for selected ROIs were from 2.2 to 5.4 mm for Demons, from 2.3 to 6.8 mm for intensity-based, and from 2.4 to 11.4 mm for B-Spline. The average absolute dose errors for selected ROIs were from 0.2 to 0.6 Gy for Demons, from 0.1 to 0.5 Gy for intensity-based, and from 0.5 to 1.5 Gy for B-Spline. Conclusion: Virtual phantoms were modeled after patients with lung cancer and were clinically relevant for adaptive radiotherapy treatment replanning. Virtual phantoms with known DVFs serve as references and can provide a fair comparison when evaluating different DIRs. Demons and intensity-based DIRs were shown to have smaller geometric and dosimetric uncertainties than B-Spline. Z Shen: None; K Bzdusek: an employee of Philips Healthcare; J Greskovich: None; P Xia

Applicability and dosimetric impact of ultrasound-based preplanning in high-dose-rate brachytherapy of prostate cancer

International Nuclear Information System (INIS)

Aebersold, D.M.; Isaak, B.; Behrensmeier, F.; Kolotas, C.; Mini, R.; Greiner, R.H.; Thalmann, G.; Kranzbuehler, H.

2004-01-01

Background and purpose: analyses of permanent brachytherapy seed implants of the prostate have demonstrated that the use of a preplan may lead to a considerable decrease of dosimetric implant quality. The authors aimed to determine whether the same drawbacks of preplanning also apply to high-dose-rate (HDR) brachytherapy. Patients and methods: 15 patients who underwent two separate HDR brachytherapy implants in addition to external-beam radiation therapy for advanced prostate cancer were analyzed. A pretherapeutic transrectal ultrasound was performed in all patients to generate a preplan for the first brachytherapy implant. For the second brachytherapy, a subset of patients were treated by preplans based on the ultrasound from the first brachytherapy implant. Preplans were compared with the respective postplans assessing the following parameters: coverage index, minimum target dose, homogeneity index, and dose exposure of organs at risk. The prostate geometries (volume, width, height, length) were compared as well. Results: at the first brachytherapy, the matching between the preplan and actual implant geometry was sufficient in 47% of the patients, and the preplan could be applied. The dosimetric implant quality decreased considerably: the mean coverage differed by -0.11, the mean minimum target dose by -0.15, the mean homogeneity index by -0.09. The exposure of organs at risk was not substantially altered. At the second brachytherapy, all patients could be treated by the preplan; the differences between the implant quality parameters were less pronounced. The changes of prostate geometry between preplans and postplans were considerable, the differences in volume ranging from -8.0 to 13.8 cm 3 and in dimensions (width, height, length) from -1.1 to 1.0 cm. Conclusion: preplanning in HDR brachytherapy of the prostate is associated with a substantial decrease of dosimetric implant quality, when the preplan is based on a pretherapeutic ultrasound. The implant quality

Contribution of customised dosimetry for small animal to the treatments of cancers by metabolic radiotherapy

International Nuclear Information System (INIS)

Boutaleb, Samir

2010-01-01

This research thesis first reports a bibliographical study which addressed the use of ionizing radiations in cancer therapy (evolution from ionizing radiation to metabolic radiotherapy, biological and physical parameters, and absorbed dose in metabolic radiotherapy) and the role imagery has in customised dosimetry (absorbed dose calculation methods, determination of cumulative activity, dosimetric models for S factor calculation). Then, the author presents a software which has been specifically developed for the creation of dosimetric models, and reports its validation. He reports the comparison between different dosimetric models in the case of mice. He highlights two applications of the developed tool: radio-immunotherapy and metabolic radiotherapy. He finally proposes a general discussion on the impact of small animal dosimetry on metabolic radiotherapy [fr

Dosimetric comparison of water phantoms, ion chambers, and data acquisition modes for LINAC characterization

International Nuclear Information System (INIS)

Cruz, Wilbert; Narayanasamy, Ganesh; Papanikolaou, Niko; Stathakis, Sotirios

2015-01-01

Purpose: In this study a dosimetric comparison utilizing continuous data acquisition and discrete data acquisition is examined using IBA Blue Phantom (IBA Dosimetry, Schwarzenbruck, Germany) and PTW (PTW, Freiberg, Germany) MP3-M water tanks. The tanks were compared according to several factors including set up time, ease of use, and data acquisition times. A tertiary objective is to study the response of several ionization chambers in the two tanks examined. Methods: Measurements made using a Varian 23EX LINAC (Varian Medical Systems, Palo Alto, CA) include PDDs and beam profiles for various field sizes with IBA CC13, PTW Semiflex 31010, PTW Pinpoint N31016, and PTW 31013 ion chambers for photons (6, 18 MV) and electrons (6, 9, 12, 15, and 18 MeV). Radial and transverse profile scans were done at depths of maximum dose, 5 cm, 10 cm, and 20 cm using the same set of tanks and detectors for the photon beams. Radial and transverse profile scans were done at depth of maximum dose for the electron beams on the same tanks and chambers. Data processing and analysis was performed using PTW's MEPHYSTO Navigator software and IBA's OmniPro Accept version 6.6 for the respective water tank systems. Results: PDD values agree to within 1% and dmax to within 1 mm for the PTW MP3-M tank using PTW 31010 and Blue Phantom using IBA CC13 chamber, respectively and larger discrepancy with the PTW PinPoint N31016 chamber at 6 MV. With respect to setup time the PTW MP3-M and IBA Blue phantom tank took about 20 and 40 min, respectively. Scan times were longer by 5–15 min per field size in the PTW MP3-M tank for the square field sizes from 1 cm to 40 cm as compared to the IBA Blue phantom. However, data processing times were higher by 7 min per field size with the IBA system. Conclusions: Tank measurements showed little deviation with the higher energy photons as compared to the lower energy photons with regards to the PDD measurements. Chamber construction as well as tank

Dosimetric and Radiobiologic Comparison of 3D Conformal Versus Intensity Modulated Planning Techniques for Prostate Bed Radiotherapy

International Nuclear Information System (INIS)

Koontz, Bridget F.; Das, Shiva; Temple, Kathy; Bynum, Sigrun; Catalano, Suzanne; Koontz, Jason I.; Montana, Gustavo S.; Oleson, James R.

2009-01-01

Adjuvant radiotherapy for locally advanced prostate cancer improves biochemical and clinical disease-free survival. While comparisons in intact prostate cancer show a benefit for intensity modulated radiation therapy (IMRT) over 3D conformal planning, this has not been studied for post-prostatectomy radiotherapy (RT). This study compares normal tissue and target dosimetry and radiobiological modeling of IMRT vs. 3D conformal planning in the postoperative setting. 3D conformal plans were designed for 15 patients who had been treated with IMRT planning for salvage post-prostatectomy RT. The same computed tomography (CT) and target/normal structure contours, as well as prescription dose, was used for both IMRT and 3D plans. Normal tissue complication probabilities (NTCPs) were calculated based on the dose given to the bladder and rectum by both plans. Dose-volume histogram and NTCP data were compared by paired t-test. Bladder and rectal sparing were improved with IMRT planning compared to 3D conformal planning. The volume of the bladder receiving at least 75% (V75) and 50% (V50) of the dose was significantly reduced by 28% and 17%, respectively (p = 0.002 and 0.037). Rectal dose was similarly reduced, V75 by 33% and V50 by 17% (p = 0.001 and 0.004). While there was no difference in the volume of rectum receiving at least 65 Gy (V65), IMRT planning significant reduced the volume receiving 40 Gy or more (V40, p = 0.009). Bladder V40 and V65 were not significantly different between planning modalities. Despite these dosimetric differences, there was no significant difference in the NTCP for either bladder or rectal injury. IMRT planning reduces the volume of bladder and rectum receiving high doses during post-prostatectomy RT. Because of relatively low doses given to the bladder and rectum, there was no statistically significant improvement in NTCP between the 3D conformal and IMRT plans.

Dosimetric and radiobiologic comparison of 3D conformal versus intensity modulated planning techniques for prostate bed radiotherapy.

Science.gov (United States)

Koontz, Bridget F; Das, Shiva; Temple, Kathy; Bynum, Sigrun; Catalano, Suzanne; Koontz, Jason I; Montana, Gustavo S; Oleson, James R

2009-01-01

Adjuvant radiotherapy for locally advanced prostate cancer improves biochemical and clinical disease-free survival. While comparisons in intact prostate cancer show a benefit for intensity modulated radiation therapy (IMRT) over 3D conformal planning, this has not been studied for post-prostatectomy radiotherapy (RT). This study compares normal tissue and target dosimetry and radiobiological modeling of IMRT vs. 3D conformal planning in the postoperative setting. 3D conformal plans were designed for 15 patients who had been treated with IMRT planning for salvage post-prostatectomy RT. The same computed tomography (CT) and target/normal structure contours, as well as prescription dose, was used for both IMRT and 3D plans. Normal tissue complication probabilities (NTCPs) were calculated based on the dose given to the bladder and rectum by both plans. Dose-volume histogram and NTCP data were compared by paired t-test. Bladder and rectal sparing were improved with IMRT planning compared to 3D conformal planning. The volume of the bladder receiving at least 75% (V75) and 50% (V50) of the dose was significantly reduced by 28% and 17%, respectively (p = 0.002 and 0.037). Rectal dose was similarly reduced, V75 by 33% and V50 by 17% (p = 0.001 and 0.004). While there was no difference in the volume of rectum receiving at least 65 Gy (V65), IMRT planning significant reduced the volume receiving 40 Gy or more (V40, p = 0.009). Bladder V40 and V65 were not significantly different between planning modalities. Despite these dosimetric differences, there was no significant difference in the NTCP for either bladder or rectal injury. IMRT planning reduces the volume of bladder and rectum receiving high doses during post-prostatectomy RT. Because of relatively low doses given to the bladder and rectum, there was no statistically significant improvement in NTCP between the 3D conformal and IMRT plans.

Dosimetric comparison of intensity modulated radiation, Proton beam therapy and proton arc therapy for para-aortic lymph node tumor

Energy Technology Data Exchange (ETDEWEB)

Kim, Jung Hoon [Dept. of Radiation Oncology, Konyang University Hospital. Daejeon (Korea, Republic of)

2014-12-15

To test feasibility of proton arc therapy (PAT) in the treatment of para-aortic lymph node tumor and compare its dosimetric properties with advanced radiotherapy techniques such as intensity modulated radiation therapy (IMRT) and conventional 3D conformal proton beam therapy (PBT). The treatment plans for para-aortic lymph node tumor were planned for 9 patients treated at our institution using IMRT, PBT, and PAT. Feasibility test and dosimetric evaluation were based on comparisons of dose volume histograms (DVHs) which reveal mean dose, D{sub 30%}, D{sub 60%}, D{sub 90%}, V{sub 30%}, V{sub 60%}, V{sub 90}%, organ equivalent doses (OEDs), normal tissue complication probability (NTCP), homogeneity index (HI) and conformity index (CI). The average doses delivered by PAT to the liver, kidney, small bowel, duodenum, stomach were 7.6%, 3%, 17.3%, 26.7%, and 14.4%, of the prescription dose (PD), respectively, which is higher than the doses delivered by IMRT (0.4%, 7.2%, 14.2%, 15.9%, and 12.8%, respectively) and PBT (4.9%, 0.5%, 14.12%, 16.1% 9.9%, respectively). The average homogeneity index and conformity index of tumor using PAT were 12.1 and 1.21, respectively which were much better than IMRT (21.5 and 1.47, respectively) and comparable to PBT (13.1 and 1.23, respectively). The result shows that both NTCP and OED of PAT are generally lower than IMRT and PBT. This study demonstrates that PAT is better in target conformity and homogeneity than IMRT and PBT but worse than IMRT and PBT for most of dosimetric factor which indicate that PAT is not recommended for the treatment of para-aortic lymph node tumor.

SU-F-J-64: Comparison of Dosimetric Robustness Between Proton Therapy and IMRT Plans Following Tumor Regression for Locally Advanced Non-Small Cell Lung Cancer (NSCLC)

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Teng, C; Ainsley, C; Teo, B; Burgdorf, B; Berman, A; Levin, W; Xiao, Y; Lin, L; Simone, C; Solberg, T [University of Pennsylvania, Philadelphia, PA (United States); Janssens, G [IBA, Louvain-la-Neuve (Belgium)

2016-06-15

Purpose: In the light of tumor regression and normal tissue changes, dose distributions can deviate undesirably from what was planned. As a consequence, replanning is sometimes necessary during treatment to ensure continued tumor coverage or to avoid overdosing organs at risk (OARs). Proton plans are generally thought to be less robust than photon plans because of the proton beam’s higher sensitivity to changes in tissue composition, suggesting also a higher likely replanning rate due to tumor regression. The purpose of this study is to compare dosimetric deviations between forward-calculated double scattering (DS) proton plans with IMRT plans upon tumor regression, and assesses their impact on clinical replanning decisions. Methods: Ten consecutive locally advanced NSCLC patients whose tumors shrank > 50% in volume and who received four or more CT scans during radiotherapy were analyzed. All the patients received proton radiotherapy (6660 cGy, 180 cGy/fx). Dosimetric robustness during therapy was characterized by changes in the planning objective metrics as well as by point-by-point root-mean-squared differences for the entire PTV, ITV, and OARs (heart, cord, esophagus, brachial plexus and lungs) DVHs. Results: Sixty-four pairs of DVHs were reviewed by three clinicians, who requested a replanning rate of 16.7% and 18.6% for DS and IMRT plans, respectively, with a high agreement between providers. Robustness of clinical indicators was found to depend on the beam orientation and dose level on the DVH curve. Proton dose increased most in OARs distal to the PTV along the beam path, but these changes were primarily in the mid to low dose levels. In contrast, the variation in IMRT plans occurred primarily in the high dose region. Conclusion: Robustness of clinical indicators depends where on the DVH curves comparisons are made. Similar replanning rates were observed for DS and IMRT plans upon large tumor regression.

Dosimetric comparison of Acuros XB, AAA, and XVMC in stereotactic body radiotherapy for lung cancer

International Nuclear Information System (INIS)

Tsuruta, Yusuke; Nakata, Manabu; Higashimura, Kyoji; Nakamura, Mitsuhiro; Matsuo, Yukinori; Monzen, Hajime; Mizowaki, Takashi; Hiraoka, Masahiro

2014-01-01

Purpose: To compare the dosimetric performance of Acuros XB (AXB), anisotropic analytical algorithm (AAA), and x-ray voxel Monte Carlo (XVMC) in heterogeneous phantoms and lung stereotactic body radiotherapy (SBRT) plans. Methods: Water- and lung-equivalent phantoms were combined to evaluate the percentage depth dose and dose profile. The radiation treatment machine Novalis (BrainLab AG, Feldkirchen, Germany) with an x-ray beam energy of 6 MV was used to calculate the doses in the composite phantom at a source-to-surface distance of 100 cm with a gantry angle of 0°. Subsequently, the clinical lung SBRT plans for the 26 consecutive patients were transferred from the iPlan (ver. 4.1; BrainLab AG) to the Eclipse treatment planning systems (ver. 11.0.3; Varian Medical Systems, Palo Alto, CA). The doses were then recalculated with AXB and AAA while maintaining the XVMC-calculated monitor units and beam arrangement. Then the dose-volumetric data obtained using the three different radiation dose calculation algorithms were compared. Results: The results from AXB and XVMC agreed with measurements within ±3.0% for the lung-equivalent phantom with a 6 × 6 cm 2 field size, whereas AAA values were higher than measurements in the heterogeneous zone and near the boundary, with the greatest difference being 4.1%. AXB and XVMC agreed well with measurements in terms of the profile shape at the boundary of the heterogeneous zone. For the lung SBRT plans, AXB yielded lower values than XVMC in terms of the maximum doses of ITV and PTV; however, the differences were within ±3.0%. In addition to the dose-volumetric data, the dose distribution analysis showed that AXB yielded dose distribution calculations that were closer to those with XVMC than did AAA. Means ± standard deviation of the computation time was 221.6 ± 53.1 s (range, 124–358 s), 66.1 ± 16.0 s (range, 42–94 s), and 6.7 ± 1.1 s (range, 5–9 s) for XVMC, AXB, and AAA, respectively. Conclusions: In the phantom

Dosimetric comparison of Acuros XB, AAA, and XVMC in stereotactic body radiotherapy for lung cancer.

Science.gov (United States)

Tsuruta, Yusuke; Nakata, Manabu; Nakamura, Mitsuhiro; Matsuo, Yukinori; Higashimura, Kyoji; Monzen, Hajime; Mizowaki, Takashi; Hiraoka, Masahiro

2014-08-01

To compare the dosimetric performance of Acuros XB (AXB), anisotropic analytical algorithm (AAA), and x-ray voxel Monte Carlo (XVMC) in heterogeneous phantoms and lung stereotactic body radiotherapy (SBRT) plans. Water- and lung-equivalent phantoms were combined to evaluate the percentage depth dose and dose profile. The radiation treatment machine Novalis (BrainLab AG, Feldkirchen, Germany) with an x-ray beam energy of 6 MV was used to calculate the doses in the composite phantom at a source-to-surface distance of 100 cm with a gantry angle of 0°. Subsequently, the clinical lung SBRT plans for the 26 consecutive patients were transferred from the iPlan (ver. 4.1; BrainLab AG) to the Eclipse treatment planning systems (ver. 11.0.3; Varian Medical Systems, Palo Alto, CA). The doses were then recalculated with AXB and AAA while maintaining the XVMC-calculated monitor units and beam arrangement. Then the dose-volumetric data obtained using the three different radiation dose calculation algorithms were compared. The results from AXB and XVMC agreed with measurements within ± 3.0% for the lung-equivalent phantom with a 6 × 6 cm(2) field size, whereas AAA values were higher than measurements in the heterogeneous zone and near the boundary, with the greatest difference being 4.1%. AXB and XVMC agreed well with measurements in terms of the profile shape at the boundary of the heterogeneous zone. For the lung SBRT plans, AXB yielded lower values than XVMC in terms of the maximum doses of ITV and PTV; however, the differences were within ± 3.0%. In addition to the dose-volumetric data, the dose distribution analysis showed that AXB yielded dose distribution calculations that were closer to those with XVMC than did AAA. Means ± standard deviation of the computation time was 221.6 ± 53.1 s (range, 124-358 s), 66.1 ± 16.0 s (range, 42-94 s), and 6.7 ± 1.1 s (range, 5-9 s) for XVMC, AXB, and AAA, respectively. In the phantom evaluations, AXB and XVMC agreed better with

Dosimetric system for prolonged manned flights

International Nuclear Information System (INIS)

Akatov, Yu.A.; Kovalev, E.E.; Sakovich, V.A.; Deme, Sh.; Fekher, I.; Nguen, V.D.

1991-01-01

Comments for the All-Union state standard 25645.202-83 named Radiation safety of a spacecraft crew during space flight. Requirements for personnel dosimetric control, are given. Devices for the dosimetric control used in manned space flights nowadays are reviewed. The performance principle and structure of the FEDOR dosimetric complex under development are discussed

Dosimetric evaluation of three adaptive strategies for prostate cancer treatment including pelvic lymph nodes irradiation.

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Cantin, Audrey; Gingras, Luc; Lachance, Bernard; Foster, William; Goudreault, Julie; Archambault, Louis

2015-12-01

The movements of the prostate relative to the pelvic lymph nodes during intensity-modulated radiation therapy treatment can limit margin reduction and affect the protection of the organs at risk (OAR). In this study, the authors performed an analysis of three adaptive treatment strategies that combine information from both bony and gold marker registrations. The robustness of those treatments against the interfraction prostate movements was evaluated. A retrospective study was conducted on five prostate cancer patients with 7-13 daily cone-beam CTs (CBCTs). The clinical target volumes (CTVs) consisting of pelvic lymph nodes, prostate, and seminal vesicles as well as the OARs were delineated on each CBCT and the initial CT. Three adaptive strategies were analyzed. Two of these methods relied on a two-step patient positioning at each fraction. First step: a bony registration was used to deliver the nodal CTV prescription. Second step: a gold marker registration was then used either to (1) complete the dose delivered to the prostate (complement); (2) or give almost the entire prescription to the prostate with a weak dose gradient between the targets to compensate for possible motions (gradient). The third method (COR) used a pool of precalculated plans based on images acquired at previous treatment fractions. At each new fraction, a plan is selected from that pool based on the daily position of prostate center-of-mass. The dosimetric comparison was conducted and results are presented with and without the systematic shift in the prostate position on the CT planning. The adaptive strategies were compared to the current clinical standard where all fractions are treated with the initial nonadaptive plan. The minimum daily prostate D95% is improved by 2%, 9%, and 6% for the complement, the gradient, and the COR approaches, respectively, compared to the nonadaptive method. The average nodal CTV D95% remains constant across the strategies, except for the gradient approach

Dosimetric evaluation of three adaptive strategies for prostate cancer treatment including pelvic lymph nodes irradiation

International Nuclear Information System (INIS)

Cantin, Audrey; Gingras, Luc; Archambault, Louis; Lachance, Bernard; Foster, William; Goudreault, Julie

2015-01-01

Purpose: The movements of the prostate relative to the pelvic lymph nodes during intensity-modulated radiation therapy treatment can limit margin reduction and affect the protection of the organs at risk (OAR). In this study, the authors performed an analysis of three adaptive treatment strategies that combine information from both bony and gold marker registrations. The robustness of those treatments against the interfraction prostate movements was evaluated. Methods: A retrospective study was conducted on five prostate cancer patients with 7–13 daily cone-beam CTs (CBCTs). The clinical target volumes (CTVs) consisting of pelvic lymph nodes, prostate, and seminal vesicles as well as the OARs were delineated on each CBCT and the initial CT. Three adaptive strategies were analyzed. Two of these methods relied on a two-step patient positioning at each fraction. First step: a bony registration was used to deliver the nodal CTV prescription. Second step: a gold marker registration was then used either to (1) complete the dose delivered to the prostate (complement); (2) or give almost the entire prescription to the prostate with a weak dose gradient between the targets to compensate for possible motions (gradient). The third method (COR) used a pool of precalculated plans based on images acquired at previous treatment fractions. At each new fraction, a plan is selected from that pool based on the daily position of prostate center-of-mass. The dosimetric comparison was conducted and results are presented with and without the systematic shift in the prostate position on the CT planning. The adaptive strategies were compared to the current clinical standard where all fractions are treated with the initial nonadaptive plan. Results: The minimum daily prostate D 95% is improved by 2%, 9%, and 6% for the complement, the gradient, and the COR approaches, respectively, compared to the nonadaptive method. The average nodal CTV D 95% remains constant across the strategies

Dosimetric comparison of three intensity-modulated radiation therapies for left breast cancer after breast-conserving surgery.

Science.gov (United States)

Zhang, Huai-Wen; Hu, Bo; Xie, Chen; Wang, Yun-Lai

2018-05-01

This study aimed to evaluate dosimetric differences of intensity-modulated radiation therapy (IMRT) in target and normal tissues after breast-conserving surgery. IMRT five-field plan I, IMRT six-field plan II, and field-in-field-direct machine parameter optimization-IMRT plan III were designed for each of the 50 patients. One-way analysis of variance was performed to compare differences, and P mean dose (D mean ) for the heart (P optimization-IMRT plans III can reduce doses and volumes to the lungs and heart better while maintaining satisfying conformity index and homogeneity index of target. Nevertheless, plan II neglects target movements caused by respiration. In the same manner, plan III can substantially reduce MU and shorten patient treatment time. Therefore, plan III, which considers target movement caused by respiration, is a more practical radiation mode. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Investigation of clinical and dosimetric factors associated with postoperative pulmonary complications in esophageal cancer patients treated with concurrent chemoradiotherapy followed by surgery

International Nuclear Information System (INIS)

Wang Shulian; Liao Zhongxing; Vaporciyan, Ara A.; Tucker, Susan L.; Liu, Helen; Wei Xiong; Swisher, Stephen; Ajani, Jaffer A.; Cox, James D.; Komaki, Ritsuko

2006-01-01

Purpose: To assess the association of clinical and especially dosimetric factors with the incidence of postoperative pulmonary complications among esophageal cancer patients treated with concurrent chemoradiation therapy followed by surgery. Method and Materials: Data from 110 esophageal cancer patients treated between January 1998 and December 2003 were analyzed retrospectively. All patients received concurrent chemoradiotherapy followed by surgery; 72 patients also received irinotecan-based induction chemotherapy. Concurrent chemotherapy was 5-fluorouracil-based and in 97 cases included taxanes. Radiotherapy was delivered to a total dose of 41.4-50.4 Gy at 1.8-2.0 Gy per fraction with a three-dimensional conformal technique. Surgery (three-field, Ivor-Lewis, or transhiatal esophagectomy) was performed 27-123 days (median, 45 days) after completion of radiotherapy. The following dosimetric parameters were generated from the dose-volume histogram (DVH) for total lung: lung volume, mean dose to lung, relative and absolute volumes of lung receiving more than a threshold dose (relative V dose and absolute V dose ), and absolute volume of lung receiving less than a threshold dose (volume spared, or VS dose ). Occurrence of postoperative pulmonary complications, defined as pneumonia or acute respiratory distress syndrome (ARDS) within 30 days after surgery, was the endpoint for all analyses. Fisher's exact test was used to investigate the relationship between categorical factors and incidence of postoperative pulmonary complications. Logistic analysis was used to analyze the relationship between continuous factors (e.g., V dose or VS dose ) and complication rate. Logistic regression with forward stepwise inclusion of factors was used to perform multivariate analysis of those factors having univariate significance (p < 0.05). The Mann-Whitney test was used to compare length of hospital stay in patients with and without lung complications and to compare lung volumes, VS5

Dosimetric investigation depending on tumor location in patient breast in partial breast irradiation

International Nuclear Information System (INIS)

Kim, Min Joo; Park, So Hyun; Jung, Joo Young; Woong, Cho; Suh, Tae Suk

2012-01-01

The Partial Breast Irradiation (PBI) technique, which involves radiation beam delivery techniques that use a limited range of treatment volumes, has been a challenging approach that is worthy of consideration compared to whole-breast radiation therapy (WBRT). Because of a small target volumes used in the PBI technique, the radiation dose can be safely delivered to the targeted tissue without the unwanted delivery of radiation to normal breast tissues and organ at risk (OAR), such as contralateral breast, lung and heart.Through PBI technique, better cosmetic outcomes and minimizing damages to OARs could be expected and also the daily dose can be increased with smaller number of fractionation in radiation therapy. The purpose of this study was to evaluate the dosimetric effects according to tumor locations in patient's breast for Partial Breast Irradiation (PBI) technique using three Dimensional Conformal Radiation Therapy (3DCRT), Electron Beam Radiation therapy (EBRT) and Helical-tomotherapy (H-TOMO). Dosimetric comparisons of PBI technique for 3DCRT, EBRT, and H-TOMO depending on the classified tumor locations were performed. H-TOMO delivered the low dose to lager volume to surrounding normal tissue, such as the heart and lungs compared to 3DCRT and EBRT although it had the same degree of target coverage as the other methods (3DCRT, EBRT). EBRT had a curative effect for early-stage breast cancers located in the lower and inner sections (LIQ-S, LIQ-D)

SU-E-T-332: Dosimetric Impact of Photon Energy and Treatment Technique When Knowledge Based Auto-Planning Is Implemented in Radiotherapy of Localized Prostate Cancer

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Liu, Z; Kennedy, A [Sarah Cannon, Nashville, TN (United States); Larsen, E; Grow, A; Hayes, C; Balamucki, C [North Florida Cancer Center, Gainesville, FL (United States); Salmon, H; Thompson, M [Lake City Cancer Center, Lake City, FL (United States)

2015-06-15

Purpose: The aim of this study was to investigate the dosimetric impact of the combination of photon energy and treatment technique on radiotherapy of localized prostate cancer when knowledge based planning was used. Methods: A total of 16 patients with localized prostate cancer were retrospectively retrieved from database and used for this study. For each patient, four types of treatment plans with different combinations of photon energy (6X and 10X) and treatment techniques (7-field IMRT and 2-arc VMAT) were created using a prostate DVH estimation model in RapidPlan™ and Eclipse treatment planning system (Varian Medical System). For any beam arrangement, DVH objectives and weighting priorities were generated based on the geometric relationship between the OAR and PTV. Photon optimization algorithm was used for plan optimization and AAA algorithm was used for final dose calculation. Plans were evaluated in terms of the pre-defined dosimetric endpoints for PTV, rectum, bladder, penile bulb, and femur heads. A Student’s paired t-test was used for statistical analysis and p > 0.05 was considered statistically significant. Results: For PTV, V95 was statistically similar among all four types of plans, though the mean dose of 10X plans was higher than that of 6X plans. VMAT plans showed higher heterogeneity index than IMRT plans. No statistically significant difference in dosimetry metrics was observed for rectum, bladder, and penile bulb among plan types. For left and right femur, VMAT plans had a higher mean dose than IMRT plans regardless of photon energy, whereas the maximum dose was similar. Conclusion: Overall, the dosimetric endpoints were similar regardless of photon energy and treatment techniques when knowledge based auto planning was used. Given the similarity in dosimetry metrics of rectum, bladder, and penile bulb, the genitourinary and gastrointestinal toxicities should be comparable among the selections of photon energy and treatment techniques.

SU-E-J-169: The Dosimetric and Temporal Effects of Respiratory-Gated Radiation Therapy in Lung Cancer Patients

International Nuclear Information System (INIS)

Rouabhi, O; Gross, B; Xia, J; Bayouth, J

2015-01-01

Purpose: To evaluate the dosimetric and temporal effects of high dose rate treatment mode for respiratory-gated radiation therapy in lung cancer patients. Methods: Treatment plans from five lung cancer patients (3 nongated (Group 1), 2 gated at 80EX-80IN (Group 2)) were retrospectively evaluated. The maximum tumor motions range from 6–12 mm. Using the same planning criteria, four new treatment plans, corresponding to four gating windows (20EX–20IN, 40EX–40IN, 60EX–60IN, and 80EX–80IN), were generated for each patient. Mean tumor dose (MTD), mean lung dose (MLD), and lung V20 were used to assess the dosimetric effects. A MATLAB algorithm was developed to compute treatment time by considering gantry rotation time, time to position collimator leaves, dose delivery time (scaled relative to the gating window), and communication overhead. Treatment delivery time for each plan was estimated using a 500 MU/min dose rate for the original plans and a 1500 MU/min dose rate for the gated plans. Results: Differences in MTD were less than 1Gy across plans for all five patients. MLD and lung V20 were on average reduced between −16.1% to −6.0% and −20.0% to −7.2%, respectively for non-gated plans when compared with the corresponding gated plans, and between − 5.8% to −4.2% and −7.0% to −5.4%, respectively for plans originally gated at 80EX–80IN when compared with the corresponding 20EX-20IN to 60EX– 60IN gated plans. Treatment delivery times of gated plans using high dose rate were reduced on average between −19.7% (−1.9min) to −27.2% (−2.7min) for originally non-gated plans and −15.6% (−0.9min) to −20.3% (−1.2min) for originally 80EX-80IN gated plans. Conclusion: Respiratory-gated radiation therapy in lung cancer patients can reduce lung toxicity, while maintaining tumor dose. Using a gated high-dose-rate treatment, delivery time comparable to non-gated normal-dose-rate treatment can be achieved. This research is supported by Siemens

Needle migration and dosimetric impact in high-dose-rate brachytherapy for prostate cancer evaluated by repeated MRI.

Science.gov (United States)

Buus, Simon; Lizondo, Maria; Hokland, Steffen; Rylander, Susanne; Pedersen, Erik M; Tanderup, Kari; Bentzen, Lise

To quantify needle migration and dosimetric impact in high-dose-rate brachytherapy for prostate cancer and propose a threshold for needle migration. Twenty-four high-risk prostate cancer patients treated with an HDR boost of 2 × 8.5 Gy were included. Patients received an MRI for planning (MRI1), before (MRI2), and after treatment (MRI3). Time from needle insertion to MRI3 was ∼3 hours. Needle migration was evaluated from coregistered images: MRI1-MRI2 and MRI1-MRI3. Dose volume histogram parameters from the treatment plan based on MRI1 were related to parameters based on needle positions in MRI2 or MRI3. Regression was used to model the average needle migration per implant and change in D90 clinical target volume, CTV prostate+3mm . The model fit was used for estimating the dosimetric impact in equivalent dose in 2 Gy fractions for dose levels of 6, 8.5, 10, 15, and 19 Gy. Needle migration was on average 2.2 ± 1.8 mm SD from MRI1-MRI2 and 5.0 ± 3.0 mm SD from MRI1-MRI3. D90 CTV prostate+3mm was robust toward average needle migration ≤3 mm, whereas for migration >3 mm D90 decreased by 4.5% per mm. A 3 mm of needle migration resulted in a decrease of 0.9, 1.7, 2.3, 4.8, and 7.6 equivalent dose in 2 Gy fractions for dose levels of 6, 8.5, 10, 15, and 19 Gy, respectively. Substantial needle migration in high-dose-rate brachytherapy occurs frequently in 1-3 hours following needle insertion. A 3-mm threshold of needle migration is proposed, but 2 mm may be considered for dose levels ≥15 Gy. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Effect of photon-beam energy on VMAT and IMRT treatment plan quality and dosimetric accuracy for advanced prostate cancer

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Pasler, Marlies; Wirtz, Holger; Lutterbach, Johannes [Lake Constance Radiation Oncology Center Singen-Friedrichshafen, Singen (Germany); Georg, Dietmar [Medical Univ. Vienna (Austria). Dept. of Radiotherapy

2011-12-15

The goal of the research was to evaluate treatment plan quality and dosimetric accuracy of volumetric modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) plans using 6, 10, and 15 MV photon beams for prostate cancer including lymph nodes. In this retrospective study, VMAT and IMRT plans were generated with the Pinnacle {sup copyright} treatment planning system (TPS) (V9.0) for 10 prostate cancer cases. Each plan consisted of two target volumes: PTV{sub B} included the prostate bed, PTV{sub PC+LN} contained PTV{sub B} and lymph nodes. For plan evaluation statistics, the homogeneity index, conformity index, mean doses, and near-max doses to organs at risk (OAR) were analyzed. Treatment time and number of monitor units were assessed to compare delivery efficiency. Dosimetric plan verification was performed with a 2D ionization chamber array placed in a full scatter phantom. Results: No differences were found for target and OAR parameters in low and high energy photon beam plans for both VMAT and IMRT. A slightly higher low dose volume was detected for 6 MV VMAT plans (normal tissue: D{sub mean} = 16.47 Gy) compared to 10 and 15 MV VMAT plans (D{sub mean} = 15.90 Gy and 15.74 Gy, respectively), similar to the findings in IMRT. In VMAT, > 96% of detector points passed the 3%/ 3 mm {gamma} criterion; marginally better accuracy was found in IMRT (> 97%). Conclusion: For static and rotational IMRT, 15 MV photons did not show advantages over 6 and 10 MV high energy photon beams in large volume pelvic plans. For the investigated TPS and linac combination, 10 MV photon beams can be used as the general purpose energy for intensity modulation.

Dosimetric effects of immobilization devices on SABR for lung cancer using VMAT technique.

Science.gov (United States)

Park, Jong In; Ye, Sung-Joon; Kim, Hak Jae; Park, Jong Min

2015-01-08

The purpose of this study was to investigate the dosimetric effects of immobilization devices on the dose distributions of stereotactic ablative radiotherapy (SABR) for lung cancer using volumetric-modulated arc therapy (VMAT) technique. A total of 30 patients who underwent SABR for lung cancer were selected retrospectively. Every patient was immobilized using Body Pro-Lok with a vacuum bag customized for each patient body shape. Structure sets were generated to include the patient body inside the body structure with and without the immobilization device. Dose distributions, with and without the immobilization device, were calculated using identical VMAT plans for each patient. Correlations between the change in dose-volumetric parameters and the MU fraction of photon beams penetrating through the immobilization device were analyzed with Pearson correlation coefficients (r). The maximum change in D95%, D100%, and the minimum, maximum and mean dose to the planning target volume (PTV) due to the immobilization device were 5%, 7%, 4%, 5%, and 5%, respectively. The maximum changes in the maximum dose to the spinal cord, esophagus, heart, and trachea were 1.3 Gy, 0.9 Gy, 1 Gy, and 1.7 Gy, respectively. Strong correlations were observed between the changes in PTV D95%, the minimum, the maximum, and the mean dose to the PTV, the maximum dose to the esophagus and heart, and the MU fractions, showing values of r higher than 0.7. The decrease in dose to the target volume was considerable for lung SABR using VMAT technique, especially when MU fraction was large.

Comparison of Panasonic’s Dosimetric System with Gamma-31 Dosimeters

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Paweł Urban

2013-01-01

Full Text Available Equipment being used in medical or industrial institutions is often a source of ionizing radiation with different energies and types, which complicates the detection and assessment of doses. Up until now, for dosimetric measurements of ionizing radiation, Gamma-31 dosimeters have been used in the Central Mining Institute for many years. Now, this system will be expanded by a Panasonic system, for which measurement procedures were developed and comparisons with other dosimeters were held. The method is based on a four-element dosimeters UD-802 Panasonic equipped with CaSO and LiBO detectors additionally sheltered by filters of different surface mass. The use of UD-802 dosimeters, in contrast to Gamma-31 dosimeters, permits measuring radiation doses in a different range of photon energy. Consequently, it is possible to obtain a more accurate analysis of the hazards caused by gamma radiation in underground mines. The publication includes a description of the dosimetry system and presents the results of measurements conducted by means of both types of dosimeters. In order to verify the correctness of the indications of the new dosimetry system a series of measurements were carried out, which allowed examining the behaviour of the dosimeters under different environmental conditions. As a place of exposure, the selected laboratories in the Silesian Centre for Environmental Radiometry were chosen, where the work is connected with (TENORM and equipment producing ionizing radiation or containing sources of this type of radiation. Moreover, to observe the dosimeters behaviour in difficult environmental conditions, they were exposed in water treatment plants and an underground potassium salt mine.

Dosimetric analysis of urethral strictures following HDR 192Ir brachytherapy as monotherapy for intermediate- and high-risk prostate cancer

International Nuclear Information System (INIS)

Díez, Patricia; Mullassery, Vinod; Dankulchai, Pittaya; Ostler, Peter; Hughes, Robert; Alonzi, Roberto; Lowe, Gerry; Hoskin, Peter J.

2014-01-01

Background and purpose: To evaluate dosimetric parameters related to urethral strictures following high dose-rate brachytherapy (HDRBT) alone for prostate cancer. Material and methods: Ten strictures were identified in 213 patients treated with HDRBT alone receiving 34 Gy in four fractions, 36 Gy in four fractions, 31.5 Gy in 3 fractions or 26 Gy in 2 fractions. A matched-pair analysis used 2 controls for each case matched for dose fractionation schedule, pre-treatment IPSS score, number of needles used and clinical target volume. The urethra was divided into membranous urethra and inferior, mid and superior thirds of the prostatic urethra. Results: Stricture rates were 3% in the 34 Gy group, 4% in the 36 Gy group, 6% in the 31.5 Gy group and 4% in the 26 Gy group. The median time to stricture formation was 26 months (range 8–40). The dosimetric parameters investigated were not statistically different between cases and controls. No correlation was seen between stricture rate and fractionation schedule. Conclusions: Urethral stricture is an infrequent complication of prostate HDRBT when used to deliver high doses as sole treatment, with an overall incidence in this cohort of 10/213 (4.7%). In a matched pair analysis no association with dose schedule or urethral dosimetry was identified, but the small number of events limits definitive conclusions

SU-F-T-36: Dosimetric Comparison of Point Based Vs. Target Based Prescription for Intracavitary Brachytherapy in Cancer of the Cervix

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Ashenafi, M; McDonald, D; Peng, J; Mart, C; Koch, N; Cooper, L; Vanek, K [Medical University of South Carolina, Charleston, SC (United States)

2016-06-15

Purpose: Improved patient imaging used for planning the treatment of cervical cancer with Tandem and Ovoid (T&O) Intracavitary high-dose-rate brachytherapy (HDR) now allows for 3D delineation of target volumes and organs-at-risk. However, historical data relies on the conventional point A-based planning technique. A comparative dosimetric study was performed by generating both target-based (TBP) and point-based (PBP) plans for ten clinical patients. Methods: Treatment plans created using Elekta Oncentra v. 4.3 for ten consecutive cervical cancer patients were analyzed. All patients were treated with HDR using the Utrecht T&O applicator. Both CT and MRI imaging modalities were utilized to delineate clinical target volume (CTV) and organs-at-risk (rectum, sigmoid, bladder, and small bowel). Point A (left and right), vaginal mucosa, and ICRU rectum and bladder points were defined on CT. Two plans were generated for each patient using two prescription methods (PBP and TBP). 7Gy was prescribed to each point A for each PBP plan and to the target D90% for each TBP plan. Target V90%, V100%, and V200% were evaluated. In addition, D0.1cc and D2cc were analyzed for each organ-at-risk. Differences were assessed for statistical significance (p<0.05) by use of Student’s t-test. Results: Target coverage was comparable for both planning methods, with each method providing adequate target coverage. TBP showed lower absolute dose to the target volume than PBP (D90% = 7.0Gy vs. 7.4Gy, p=0.028), (V200% = 10.9cc vs. 12.8cc, p=0.014), (ALeft = 6.4Gy vs. 7Gy, p=0.009), and (ARight = 6.4Gy vs. 7Gy, p=0.013). TBP also showed a statistically significant reduction in bladder, rectum, small bowel, and sigmoid doses compared to PBP. There was no statistically significant difference in vaginal mucosa or ICRU-defined rectum and bladder dose. Conclusion: Target based prescription resulted in substantially lower dose to delineated organs-at-risk compared to point based prescription, while

Adjuvant radiation therapy for bladder cancer: A dosimetric comparison of techniques

Energy Technology Data Exchange (ETDEWEB)

Baumann, Brian C.; Noa, Kate [Department of Radiation Oncology at the University of Pennsylvania, Philadelphia, PA (United States); Wileyto, E. Paul [Department of Biostatistics and Epidemiology at the University of Pennsylvania, Philadelphia, PA (United States); Bekelman, Justin E. [Department of Radiation Oncology at the University of Pennsylvania, Philadelphia, PA (United States); Deville, Curtiland [Department of Radiation Oncology and Molecular Radiation Sciences at Johns Hopkins University School of Medicine, Baltimore, MD (United States); Vapiwala, Neha; Kirk, Maura; Both, Stefan; Dolney, Derek; Kassaee, Ali [Department of Radiation Oncology at the University of Pennsylvania, Philadelphia, PA (United States); Christodouleas, John P., E-mail: christojo@uphs.upenn.edu [Department of Radiation Oncology at the University of Pennsylvania, Philadelphia, PA (United States)

2015-01-01

Trials of adjuvant radiation after cystectomy are under development. There are no studies comparing radiation techniques to inform trial design. This study assesses the effect on bowel and rectal dose of 3 different modalities treating 2 proposed alternative clinical target volumes (CTVs). Contours of the bowel, rectum, CTV-pelvic sidewall (common/internal/external iliac and obturator nodes), and CTV-comprehensive (CTV-pelvic sidewall plus cystectomy bed and presacral regions) were drawn on simulation images of 7 post-cystectomy patients. We optimized 3-dimensional conformal radiation (3-D), intensity-modulated radiation (IMRT), and single-field uniform dose (SFUD) scanning proton plans for each CTV. Mixed models regression was used to compare plans for bowel and rectal volumes exposed to 35% (V{sub 35%}), 65% (V{sub 65%}), and 95% (V{sub 95%}) of the prescribed dose. For any given treatment modality, treating the larger CTV-comprehensive volume compared with treating only the CTV-pelvic sidewall nodes significantly increased rectal dose (V{sub 35%} {sub rectum}, V{sub 65%} {sub rectum}, and V{sub 95%} {sub rectum}; p < 0.001 for all comparisons), but it did not produce significant differences in bowel dose (V{sub 95%} {sub bowel}, V{sub 65%} {sub bowel}, or V{sub 35%} {sub bowel}). The 3-D plans, compared with both the IMRT and the SFUD plans, had a significantly greater V{sub 65%} {sub bowel} and V{sub 95%} {sub bowel} for each proposed CTV (p < 0.001 for all comparisons). The effect of treatment modality on rectal dosimetry differed by CTV, but it generally favored the IMRT and the SFUD plans over the 3-D plans. Comparison of the IMRT plan vs the SFUD plan yielded mixed results with no consistent advantage for the SFUD plan over the IMRT plan. Targeting a CTV that spares the cystectomy bed and presacral region may marginally improve rectal toxicity but would not be expected to improve the bowel toxicity associated with any given modality of adjuvant radiation

Dosimetric study of volumetric arc modulation with RapidArc and intensity-modulated radiotherapy in patients with cervical cancer and comparison with 3-dimensional conformal technique for definitive radiotherapy in patients with cervical cancer

Energy Technology Data Exchange (ETDEWEB)

Guy, Jean-Baptiste [Department of Radiation Oncology, Institut de Cancérologie de la Loire Lucien Neuwirth, Saint-Priest en Jarez (France); Falk, Alexander T. [Department of Radiation Oncology, Centre Antoine Lacassagne, Nice (France); Auberdiac, Pierre [Department of Radiation Oncology, Clinique Claude Bernard, Albi (France); Cartier, Lysian; Vallard, Alexis [Department of Radiation Oncology, Institut de Cancérologie de la Loire Lucien Neuwirth, Saint-Priest en Jarez (France); Ollier, Edouard [Department of Pharmacology-Toxicology, Centre Hospitalier Universitaire de Saint-Etienne, Saint-Priest en Jarez (France); Trone, Jane-Chloé; Khodri, Moustapha [Department of Radiation Oncology, Institut de Cancérologie de la Loire Lucien Neuwirth, Saint-Priest en Jarez (France); Chargari, Cyrus [Department of Radiation Oncology, Hôpital d’instruction de Armées du Val-de-Grâce, Paris (France); Magné, Nicolas, E-mail: nicolas.magne@icloire.fr [Department of Radiation Oncology, Institut de Cancérologie de la Loire Lucien Neuwirth, Saint-Priest en Jarez (France)

2016-04-01

Introduction: For patients with cervical cancer, intensity-modulated radiation therapy (IMRT) improves target coverage and allows dose escalation while reducing the radiation dose to organs at risk (OARs). In this study, we compared dosimetric parameters among 3-dimensional conformal radiotherapy (3D-CRT), “step-and-shoot” IMRT, and volumetric intensity-modulated arc radiotherapy (VMAT) in a series of patients with cervical cancer receiving definitive radiotherapy. Computed tomography (CT) scans of 10 patients with histologically proven cervical cancer treated with definitive radiation therapy (RT) from December 2008 to March 2010 at our department were selected for this study. The gross tumor volume (GTV) and clinical target volume (CTV) were delineated following the guidelines of the Gyn IMRT consortium that included cervix, uterus, parametrial tissues, and the pelvic nodes including presacral. The median age was 57 years (range: 30 to 85 years). All 10 patients had squamous cell carcinoma with Federation of Gynecology and Obstetrics (FIGO) stage IB-IIIB. All patients were treated by VMAT. OAR doses were significantly reduced for plans with intensity-modulated technique compared with 3D-CRT except for the dose to the vagina. Between the 2 intensity-modulated techniques, significant difference was observed for the mean dose to the small intestine, to the benefit of VMAT (p < 0.001). There was no improvement in terms of OARs sparing for VMAT although there was a tendency for a slightly decreased average dose to the rectum: − 0.65 Gy but not significant (p = 0.07). The intensity modulation techniques have many advantages in terms of quality indexes, and particularly OAR sparing, compared with 3D-CRT. Following the ongoing technologic developments in modern radiotherapy, it is essential to evaluate the intensity-modulated techniques on prospective studies of a larger scale.

Accelerated partial breast irradiation using robotic radiotherapy: a dosimetric comparison with tomotherapy and three-dimensional conformal radiotherapy.

Science.gov (United States)

Rault, Erwann; Lacornerie, Thomas; Dang, Hong-Phuong; Crop, Frederik; Lartigau, Eric; Reynaert, Nick; Pasquier, David

2016-02-27

Accelerated partial breast irradiation (APBI) is a new breast treatment modality aiming to reduce treatment time using hypo fractionation. Compared to conventional whole breast irradiation that takes 5 to 6 weeks, APBI is reported to induce worse cosmetic outcomes both when using three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT). These late normal tissue effects may be attributed to the dose volume effect because a large portion of the non-target breast tissue volume (NTBTV) receives a high dose. In the context of APBI, non-coplanar beams could spare the NTBTV more efficiently. This study evaluates the dosimetric benefit of using the Cyberknife (CK) for APBI in comparison to IMRT (Tomotherapy) and three dimensional conformal radiotherapy (3D-CRT). The possibility of using surgical clips, implanted during surgery, to track target movements is investigated first. A phantom of a female thorax was designed in-house using the measurements of 20 patients. Surgical clips of different sizes were inserted inside the breast. A treatment plan was delivered to the mobile and immobile phantom. The motion compensation accuracy was evaluated using three radiochromic films inserted inside the breast. Three dimensional conformal radiotherapy (3D-CRT), Tomotherapy (TOMO) and CK treatment plans were calculated for 10 consecutive patients who received APBI in Lille. To ensure a fair comparison of the three techniques, margins applied to the CTV were set to 10 mm. However, a second CK plan was prepared using 3 mm margins to evaluate the benefits of motion compensation. Only the larger clips (VITALITEC Medium-Large) could be tracked inside the larger breast (all gamma indices below 1 for 1 % of the maximum dose and 1 mm). All techniques meet the guidelines defined in the NSABP/RTOG and SHARE protocols. As the applied dose volume constraints are very strong, insignificant dosimetric differences exist between techniques regarding the PTV

Accelerated partial breast irradiation using robotic radiotherapy: a dosimetric comparison with tomotherapy and three-dimensional conformal radiotherapy

International Nuclear Information System (INIS)

Rault, Erwann; Lacornerie, Thomas; Dang, Hong-Phuong; Crop, Frederik; Lartigau, Eric; Reynaert, Nick; Pasquier, David

2016-01-01

Accelerated partial breast irradiation (APBI) is a new breast treatment modality aiming to reduce treatment time using hypo fractionation. Compared to conventional whole breast irradiation that takes 5 to 6 weeks, APBI is reported to induce worse cosmetic outcomes both when using three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT). These late normal tissue effects may be attributed to the dose volume effect because a large portion of the non-target breast tissue volume (NTBTV) receives a high dose. In the context of APBI, non-coplanar beams could spare the NTBTV more efficiently. This study evaluates the dosimetric benefit of using the Cyberknife (CK) for APBI in comparison to IMRT (Tomotherapy) and three dimensional conformal radiotherapy (3D-CRT). The possibility of using surgical clips, implanted during surgery, to track target movements is investigated first. A phantom of a female thorax was designed in-house using the measurements of 20 patients. Surgical clips of different sizes were inserted inside the breast. A treatment plan was delivered to the mobile and immobile phantom. The motion compensation accuracy was evaluated using three radiochromic films inserted inside the breast. Three dimensional conformal radiotherapy (3D-CRT), Tomotherapy (TOMO) and CK treatment plans were calculated for 10 consecutive patients who received APBI in Lille. To ensure a fair comparison of the three techniques, margins applied to the CTV were set to 10 mm. However, a second CK plan was prepared using 3 mm margins to evaluate the benefits of motion compensation. Only the larger clips (VITALITEC Medium-Large) could be tracked inside the larger breast (all gamma indices below 1 for 1 % of the maximum dose and 1 mm). All techniques meet the guidelines defined in the NSABP/RTOG and SHARE protocols. As the applied dose volume constraints are very strong, insignificant dosimetric differences exist between techniques regarding the PTV

Comparison of dosimetric properties of three commercial multi leaf collimator systems

International Nuclear Information System (INIS)

Hoever, K.H.; Hesse, B.M.; Haering, P.; Rhein, B.; Bannach, B.; Doll, T.; Doerner, K.J.

1996-01-01

Purpose: The dosimetric properties of different designs of multi leaf collimators used for the generation of irregular fields will be measured and compared with each other. Using multi leaf collimators is a practical method of achieving conformal therapy. The use for complex conformal treatment fields to be given in either in static or dynamic mode depends much on the leaf end penumbra and the leaf side penumbra as well as the transmission through the leafs. Penumbra and leakage caused by the leaves therefore are of special interest in this intercomparison. Material and Methods: To investigate the dosimetric properties of three multi leaf collimators of different technical design, measurements have been taken at two different facilities. Until now, comparative measurements have been performed for the following devices. The new Siemens double focusing MLC with 29 opposite leaf pairs, installed at the Mevatron Experimental in the German Cancer Research Center, Heidelberg. The energy used was 15 MV and 6 MV. The Philips quasi-double focusing MLC with 40 opposite leaf pairs, installed at the SL25 in the University Duesseldorf. The leaves move in a plane rather than on a circular arc and have rounded ends to reduce penumbra. The energy used was 25 MV and 6 MV. The Leibinger non-focusing micro-MLC with 40 opposite leaf pairs. This MLC was specially designed for stereotactic irradiation of the brain. The comparative study is to be continued and extended to involve additional devices in the future. Both, the film densitometry and a newly designed ten-bit Beam Imaging System BIS-710 developed by Wellhoefer company were used. The BIS-710 was developed especially for quantitative dose measuring, whereas most of the existing Portal Imaging Systems are used for image display only. The BIS-710 contains a camera for 10-bit digital data output. The size of each of the 512 x 512 detector elements is 0.6 mm x 0.6 mm Results: Measurements taken with the BIS-710 and with film

A Comparison of daily megavoltage CT and ultrasound image guided radiation therapy for prostate cancer

Energy Technology Data Exchange (ETDEWEB)

Peng Cheng; Kainz, Kristofer; Lawton, Colleen; Li, X. Allen [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States)

2008-12-15

In order to quantify the differences between ultrasound-imaging and megavoltage-CT (MVCT) daily prostate localization in prostate-cancer radiotherapy and their dosimetric impacts, daily shifts were analyzed for a total of 140 prostate cancer patients; 106 positioned using ultrasound-based imaging [B-mode Acquisition and Targeting (BAT)], and 34 using the MVCT from a TomoTherapy Hi-Art unit. The shifts indicated by the two systems were compared statistically along the right/left (R/L), superior/inferior (S/I), and anterior/posterior (A/P) directions. The systematic and random variations among the daily alignments were calculated. Margins to account for these shifts were estimated. The mean shifts and standard deviations along the R/L, S/I, and A/P directions were -0.11{+-}3.80, 0.67{+-}4.67, and 2.71{+-}6.31 mm for BAT localizations and -0.98{+-}5.13, 0.27{+-}3.35, and 1.00{+-}4.22 mm for MVCT localizations, respectively. The systematic and random variations in daily shifts based on MVCT were generally smaller than those based on BAT, especially along the A/P direction. A t-test showed this difference to be statistically significant. The planning target volume margins in the A/P direction estimated to account for daily variations were 8.81 and 14.66 mm based on MVCT and BAT data, respectively. There was no statistically significant difference in the daily prostate movement pattern between the first few fractions and the remaining fractions. Dosimetric comparison of MVCT and BAT prostate alignments was performed for seven fractions from a patient. The degradation from the plan caused by the MVCT alignment is trivial, while that by BAT is substantial. The MVCT technique results in smaller variations in daily shifts than ultrasound imaging, indicating that MVCT is more reliable and precise for prostate localization. Ultrasound-based localization may overestimate the daily prostate motion, particularly in the A/P direction, negatively impacting prostate dose coverage

A Comparison of daily megavoltage CT and ultrasound image guided radiation therapy for prostate cancer

International Nuclear Information System (INIS)

Peng Cheng; Kainz, Kristofer; Lawton, Colleen; Li, X. Allen

2008-01-01

In order to quantify the differences between ultrasound-imaging and megavoltage-CT (MVCT) daily prostate localization in prostate-cancer radiotherapy and their dosimetric impacts, daily shifts were analyzed for a total of 140 prostate cancer patients; 106 positioned using ultrasound-based imaging [B-mode Acquisition and Targeting (BAT)], and 34 using the MVCT from a TomoTherapy Hi-Art unit. The shifts indicated by the two systems were compared statistically along the right/left (R/L), superior/inferior (S/I), and anterior/posterior (A/P) directions. The systematic and random variations among the daily alignments were calculated. Margins to account for these shifts were estimated. The mean shifts and standard deviations along the R/L, S/I, and A/P directions were -0.11±3.80, 0.67±4.67, and 2.71±6.31 mm for BAT localizations and -0.98±5.13, 0.27±3.35, and 1.00±4.22 mm for MVCT localizations, respectively. The systematic and random variations in daily shifts based on MVCT were generally smaller than those based on BAT, especially along the A/P direction. A t-test showed this difference to be statistically significant. The planning target volume margins in the A/P direction estimated to account for daily variations were 8.81 and 14.66 mm based on MVCT and BAT data, respectively. There was no statistically significant difference in the daily prostate movement pattern between the first few fractions and the remaining fractions. Dosimetric comparison of MVCT and BAT prostate alignments was performed for seven fractions from a patient. The degradation from the plan caused by the MVCT alignment is trivial, while that by BAT is substantial. The MVCT technique results in smaller variations in daily shifts than ultrasound imaging, indicating that MVCT is more reliable and precise for prostate localization. Ultrasound-based localization may overestimate the daily prostate motion, particularly in the A/P direction, negatively impacting prostate dose coverage and rectal

Dosimetric properties of a novel brachytherapy balloon applicator for the treatment of malignant brain-tumor resection-cavity margins

International Nuclear Information System (INIS)

Dempsey, James F.; Williams, Jeffery A.; Stubbs, James B.; Patrick, Timothy J.; Williamson, Jeffrey F.

1998-01-01

Purpose: This paper characterizes the dosimetric properties of a novel balloon brachytherapy applicator for the treatment of the tissue surrounding the resection cavity of a malignant brain tumor. Methods and Materials: The applicator consists of an inflatable silicone balloon reservoir attached to a positionable catheter that is intraoperatively implanted into the resection cavity and postoperatively filled with a liquid radionuclide solution. A simple dosimetric model, valid in homogeneous media and based on results from Monte Carlo photon-transport simulations, was used to determine the dosimetric characteristics of spherical geometry balloons filled with photon-emitting radionuclide solutions. Fractional depth-dose (FDD) profiles, along with activity densities, and total activities needed to achieve specified dose rates were studied as a function of photon energy and source-containment geometry. Dose-volume histograms (DVHs) were calculated to compare idealized balloon-applicator treatments to conventional 125 I seed volume implants. Results: For achievable activity densities and total activities, classical low dose rate (LDR) treatments of residual disease at distances of up to 1 cm from the resection cavity wall are possible with balloon applicators having radii between 0.5 cm and 2.5 cm. The dose penetration of these applicators increases approximately linearly with balloon radius. The FDD profile can be made significantly more or less penetrating by combining selection of radionuclide with source-geometry manipulation. Comparisons with 125 I seed-implant DVHs show that the applicator can provide a more conformal therapy with no target tissue underdosing, less target tissue overdosing, and no healthy tissue ''hot spots;'' however, more healthy tissue volume receives a dose of the prescribed dosage or less. Conclusions: This device, when filled with 125 I solution, is suitable for classical LDR treatments and may be preferable to 125 I interstitial

Dosimetric evaluation of the feasibility of stereotactic body radiotherapy for primary lung cancer with lobe-specific selective elective nodal irradiation.

Science.gov (United States)

Komatsu, Tetsuya; Kunieda, Etsuo; Kitahara, Tadashi; Akiba, Takeshi; Nagao, Ryuta; Fukuzawa, Tsuyoshi

2016-01-01

More than 10% of all patients treated with stereotactic body radiotherapy (SBRT) for primary lung cancer develop regional lymph node recurrence. We evaluated the dosimetric feasibility of SBRT with lobe-specific selective elective nodal irradiation (ENI) on dose-volume histograms. A total of 21 patients were treated with SBRT for Stage I primary lung cancer between January 2010 and June 2012 at our institution. The extents of lobe-specific selective ENI fields were determined with reference to prior surgical reports. The ENI fields included lymph node stations (LNS) 3 + 4 + 11 for the right upper lobe tumors, LNS 7 + 11 for the right middle or lower lobe tumors, LNS 5 + 11 for the left upper lobe tumors, and LNS 7 + 11 for the left lower lobe tumors. A composite plan was generated by combining the ENI plan and the SBRT plan and recalculating for biologically equivalent doses of 2 Gy per fraction, using a linear quadratic model. The V20 of the lung, D(1cm3) of the spinal cord, D(1cm3) and D(10cm3) of the esophagus and D(10cm3) of the tracheobronchial wall were evaluated. Of the 21 patients, nine patients (43%) could not fulfill the dose constraints. In all these patients, the distance between the planning target volume (PTV) of ENI (PTVeni) and the PTV of SBRT (PTVsrt) was ≤2.0 cm. Of the three patients who developed regional metastasis, two patients had isolated lymph node failure, and the lymph node metastasis was included within the ENI field. When the distance between the PTVeni and PTVsrt is >2.0 cm, SBRT with selective ENI may therefore dosimetrically feasible. © The Author 2015. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

Dosimetric evaluation of a novel polymer gel dosimeter for proton therapy

Energy Technology Data Exchange (ETDEWEB)

Zeidan, O. A.; Sriprisan, S. I.; Lopatiuk-Tirpak, O.; Kupelian, P. A.; Meeks, S. L.; Hsi, W. C.; Li, Z.; Palta, J. R.; Maryanski, M. J. [M. D. Anderson Cancer Center Orlando, Orlando, Florida 32806 (United States); University of Florida Proton Therapy Institute, Jacksonville, Florida 32206 (United States); MGS Research, Inc., Madison, Connecticut 06443 (United States)

2010-05-15

Purpose: The aim of this study is to evaluate the dosimetric performance of a newly developed proton-sensitive polymer gel formulation for proton therapy dosimetry. Methods: Using passive scattered modulated and nonmodulated proton beams, the dose response of the gel was assessed. A next-generation optical CT scanner is used as the readout mechanism of the radiation-induced absorbance in the gel medium. Comparison of relative dose profiles in the gel to ion chamber profiles in water is performed. A simple and easily reproducible calibration protocol is established for routine gel batch calibrations. Relative stopping power ratio measurement of the gel medium was performed to ensure accurate water-equivalent depth dose scaling. Measured dose distributions in the gel were compared to treatment planning system for benchmark irradiations and quality of agreement is assessed using clinically relevant gamma index criteria. Results: The dosimetric response of the gel was mapped up to 600 cGy using an electron-based calibration technique. Excellent dosimetric agreement is observed between ion chamber data and gel. The most notable result of this work is the fact that this gel has no observed dose quenching in the Bragg peak region. Quantitative dose distribution comparisons to treatment planning system calculations show that most (>97%) of the gel dose maps pass the 3%/3 mm gamma criterion. Conclusions: This study shows that the new proton-sensitive gel dosimeter is capable of reproducing ion chamber dose data for modulated and nonmodulated Bragg peak beams with different clinical beam energies. The findings suggest that the gel dosimeter can be used as QA tool for millimeter range verification of proton beam deliveries in the dosimeter medium.

Dosimetric evaluation of a novel polymer gel dosimeter for proton therapy

International Nuclear Information System (INIS)

Zeidan, O. A.; Sriprisan, S. I.; Lopatiuk-Tirpak, O.; Kupelian, P. A.; Meeks, S. L.; Hsi, W. C.; Li, Z.; Palta, J. R.; Maryanski, M. J.

2010-01-01

Purpose: The aim of this study is to evaluate the dosimetric performance of a newly developed proton-sensitive polymer gel formulation for proton therapy dosimetry. Methods: Using passive scattered modulated and nonmodulated proton beams, the dose response of the gel was assessed. A next-generation optical CT scanner is used as the readout mechanism of the radiation-induced absorbance in the gel medium. Comparison of relative dose profiles in the gel to ion chamber profiles in water is performed. A simple and easily reproducible calibration protocol is established for routine gel batch calibrations. Relative stopping power ratio measurement of the gel medium was performed to ensure accurate water-equivalent depth dose scaling. Measured dose distributions in the gel were compared to treatment planning system for benchmark irradiations and quality of agreement is assessed using clinically relevant gamma index criteria. Results: The dosimetric response of the gel was mapped up to 600 cGy using an electron-based calibration technique. Excellent dosimetric agreement is observed between ion chamber data and gel. The most notable result of this work is the fact that this gel has no observed dose quenching in the Bragg peak region. Quantitative dose distribution comparisons to treatment planning system calculations show that most (>97%) of the gel dose maps pass the 3%/3 mm gamma criterion. Conclusions: This study shows that the new proton-sensitive gel dosimeter is capable of reproducing ion chamber dose data for modulated and nonmodulated Bragg peak beams with different clinical beam energies. The findings suggest that the gel dosimeter can be used as QA tool for millimeter range verification of proton beam deliveries in the dosimeter medium.

A dosimetric comparison of 3D-CRT, IMRT, and static tomotherapy with an SIB for large and small breast volumes

Energy Technology Data Exchange (ETDEWEB)

Michalski, Andrea [Department of Health Science (MRS), The University of Sydney, Lidcombe, New South Wales (Australia); Central Coast Cancer Centre, Gosford Hospital, Gosford, New South Wales (Australia); Atyeo, John, E-mail: john.atyeo@sydney.edu.au [Department of Health Science (MRS), The University of Sydney, Lidcombe, New South Wales (Australia); Cox, Jennifer [Department of Health Science (MRS), The University of Sydney, Lidcombe, New South Wales (Australia); Department of Radiation Oncology, Royal North Shore Hospital, St Leonards, New South Wales (Australia); Rinks, Marianne [Department of Health Science (MRS), The University of Sydney, Lidcombe, New South Wales (Australia); Radiation Oncology, Cancer Services, Illawarra Shoalhaven Local Health District, Wollongong, New South Wales (Australia); Morgia, Marita; Lamoury, Gillian [Department of Radiation Oncology, Royal North Shore Hospital, St Leonards, New South Wales (Australia)

2014-07-01

Radiation therapy to the breast is a complex task, with many different techniques that can be employed to ensure adequate dose target coverage while minimizing doses to the organs at risk. This study compares the dose planning outcomes of 3 radiation treatment modalities, 3 dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), and static tomotherapy, for left-sided whole-breast radiation treatment with a simultaneous integrated boost (SIB). Overall, 20 patients with left-sided breast cancer were separated into 2 cohorts, small and large, based on breast volume. Dose plans were produced for each patient using 3D-CRT, IMRT, and static tomotherapy. All patients were prescribed a dose of 45 Gy in 20 fractions to the breast with an SIB of 56 Gy in 20 fractions to the tumor bed and normalized so that D{sub 98%} > 95% of the prescription dose. Dosimetric comparisons were made between the 3 modalities and the interaction of patient size. All 3 modalities offered adequate planning target volume (PTV) coverage with D{sub 98%} > 95% and D{sub 2%} < 107%. Static tomotherapy offered significantly improved (p = 0.006) dose homogeneity to the PTV{sub boost} {sub eval} (0.079 ± 0.011) and breast minus the SIB volume (Breast{sub SIB}) (p < 0.001, 0.15 ± 0.03) compared with the PTV{sub boost} {sub eval} (0.085 ± 0.008, 0.088 ± 0.12) and Breast{sub SIB} (0.22 ± 0.05, 0.23 ± 0.03) for IMRT and 3D-CRT, respectively. Static tomotherapy also offered statistically significant reductions (p < 0.001) in doses to the ipsilateral lung mean dose of 6.79 ± 2.11 Gy compared with 7.75 ± 2.54 Gy and 8.29 ± 2.76 Gy for IMRT and 3D-CRT, respectively, and significantly (p < 0.001) reduced heart doses (mean = 2.83 ± 1.26 Gy) compared to both IMRT and 3D-CRT (mean = 3.70 ± 1.44 Gy and 3.91 ± 1.58 Gy). Static tomotherapy is the dosimetrically superior modality for the whole breast with an SIB compared with IMRT and 3D-CRT. IMRT is superior to 3D

Dosimetric Study of Pelvic Proton Radiotherapy for High-Risk Prostate Cancer

International Nuclear Information System (INIS)

Chera, Bhishamjit S.; Vargas, Carlos; Morris, Christopher G.; Louis, Debbie; Flampouri, Stella; Yeung, Daniel; Duvvuri, Srividya; Li Zuofeng; Mendenhall, Nancy Price

2009-01-01

Purpose: To compare dose distributions in targeted tissues (prostate, seminal vesicles, pelvic regional nodes) and nontargeted tissues in the pelvis with intensity-modulated radiotherapy (IMRT) and forward-planned, double-scattered, three-dimensional proton radiotherapy (3D-PRT). Methods and Materials: IMRT, IMRT followed by a prostate 3D-PRT boost (IMRT/3D-PRT), and 3D-PRT plans were created for 5 high-risk prostate cancer patients (n = 15 plans). A 78-CGE/Gy dose was prescribed to the prostate and proximal seminal vesicles and a 46-CGE/Gy was prescribed to the pelvic nodes. Various dosimetric endpoints were compared. Results: Target coverage of the prostate and nodal planning target volumes was adequate for all three plans. Compared with the IMRT and IMRT/3D-PRT plans, the 3D-PRT plans reduced the mean dose to the rectum, rectal wall, bladder, bladder wall, small bowel, and pelvis. The relative benefit of 3D-PRT (vs IMRT) at reducing the rectum and rectal wall V5-V40 was 53% to 71% (p < 0.05). For the bladder and bladder wall, the relative benefit for V5 to V40 CGE/Gy was 40% to 63% (p < 0.05). The relative benefit for reducing the volume of small bowel irradiated from 5 to 30 CGE/Gy in the 3D-PRT ranged from 62% to 69% (p < 0.05). Use of 3D-PRT did not produce the typical low-dose 'bath' of radiation to the pelvis seen with IMRT. Femoral head doses were higher for the 3D-PRT. Conclusions: Use of 3D-PRT significantly reduced the dose to normal tissues in the pelvis while maintaining adequate target coverage compared with IMRT or IMRT/3D-PRT. When treating the prostate, seminal vesicles, and pelvic lymph nodes in prostate cancer, proton therapy may improve the therapeutic ratio beyond what is possible with IMRT.

Quality control of dosimetric systems using thermoluminescent crystals

International Nuclear Information System (INIS)

Mahecha, L.; Plazas, M. C.; Machado, M.; Perea, M. D.

2006-01-01

To achieve an optimal tumoral control to prostate cancer in early and locally advanced stages, it is necessary to increase the dose with a low mobility probability at the vesicle an rectal level. This is achieved through conformal radiotherapy. The Instituto Nacional de Cancerologia uses this technique, but two questions arise from the medical-physicists and medical radio-oncologist: In accordance with clinical protocols, the conformal radiotherapy delivers a low dose to the adjacent healthy tissues. What experimental method exists that can prove with certainly the veracity of this affirmation?. And, Do the dosimetric simulation system calculate suitable the dose for each tissues?. Through thermoluminescent dosimetry and the use of a physical simulator,we measured the absorbed dose at the target volume and the adjacent tissues using conformal and conventional radiotherapy. We proved that organs such as the rectum and bladder, receiver a minor dose in conformal radiotherapy, hence reducing their mobility probability. In addition, the readings from the thermoluminescent dosimeters and the doses calculated by the ECLIPSE dosimetric system were compared, concluding that the patient's prescribed dose is effectively delivered as recommended by the quality control program in radiotherapy. (Author)

Dosimetric comparison between VMAT and RC3D techniques: case of prostate treatment

Science.gov (United States)

Chemingui, Fatima Zohra; Benrachi, Fatima; Bali, Mohamed Saleh; Ladjal, Hamid

2017-09-01

Considered as the second men cancer in Algeria, prostate cancer is treated in 70% by radiation. That's why radiation therapy is therapeutic weapon for prostate cancer. Conformational Radiotherapy in 3D is the most common technique [1-5]. The use of conventionally optimized treatment plans was compared at case scenario of optimized treatment plans VMAT for prostate cancer. The evaluation of the two optimizations strategies focused on the resulting plans ability to retain dose objectives under the influence of patient set up. Dose Volume Histogram in the Planning Target Volume and dose in the Organs At Risks were used to calculate the conformity index, and evaluation ratio of irradiated volume which represent the main tool of comparison [6,7]. The situation was analysed systematically. The 14% dose increase in the target leads to a decrease in the dose in adjacent organs with 39% in the bladder. Therefore, the criterion for better efficacy and less toxicity reveal that VMAT is the best choice.

Dosimetric comparison between VMAT and RC3D techniques: case of prostate treatment

Directory of Open Access Journals (Sweden)

Chemingui Fatima Zohra

2017-01-01

Full Text Available Considered as the second men cancer in Algeria, prostate cancer is treated in 70% by radiation. That's why radiation therapy is therapeutic weapon for prostate cancer. Conformational Radiotherapy in 3D is the most common technique [1−5]. The use of conventionally optimized treatment plans was compared at case scenario of optimized treatment plans VMAT for prostate cancer. The evaluation of the two optimizations strategies focused on the resulting plans ability to retain dose objectives under the influence of patient set up. Dose Volume Histogram in the Planning Target Volume and dose in the Organs At Risks were used to calculate the conformity index, and evaluation ratio of irradiated volume which represent the main tool of comparison [6,7]. The situation was analysed systematically. The 14% dose increase in the target leads to a decrease in the dose in adjacent organs with 39% in the bladder. Therefore, the criterion for better efficacy and less toxicity reveal that VMAT is the best choice.

A Monte Carlo dosimetric quality assurance system for dynamic intensity-modulated radiotherapy

International Nuclear Information System (INIS)

Takegawa, Hideki; Yamamoto, Tokihiro; Miyabe, Yuki; Teshima, Teruki; Kunugi, Tomoaki; Yano, Shinsuke; Mizowaki, Takashi; Nagata, Yasushi; Hiraoka, Masahiro

2005-01-01

We are developing a Monte Carlo (MC) dose calculation system, which can resolve dosimetric issues derived from multileaf collimator (MLC) design for routine dosimetric quality assurance (QA) of intensity-modulated radiotherapy (IMRT). The treatment head of the medical linear accelerator equipped with MLC was modeled using the EGS4 MC code. A graphical user interface (GUI) application was developed to implement MC dose computation in the CT-based patient model and compare the MC calculated results with those of a commercial radiotherapy treatment planning (RTP) system, Varian Eclipse. To reduce computation time, the EGS4 MC code has been parallelized on massive parallel processing (MPP) system using the message passing interface (MPI). The MC treatment head model and MLC model were validated by the measurement data sets of percentage depth dose (PDD) and off-center ratio (OCR) in the water phantom and the film measurements for the static and dynamic test patterns, respectively. In the treatment head model, the MC calculated results agreed with those of measurements for both of PDD and OCR. The MC could reproduce all of the MLC dosimetric effects. A quantitative comparison between the results of MC and Eclipse was successfully performed with the GUI application. Parallel speed-up became almost linear. An MC dosimetric QA system for dynamic IMRT has been developed, however there were large dose discrepancies between the MC and the measurement in the MLC model simulation, which are now being investigated. (author)

Analysis of Dosimetric Parameters Associated With Acute Gastrointestinal Toxicity and Upper Gastrointestinal Bleeding in Locally Advanced Pancreatic Cancer Patients Treated With Gemcitabine-Based Concurrent Chemoradiotherapy

International Nuclear Information System (INIS)

Nakamura, Akira; Shibuya, Keiko; Matsuo, Yukinori; Nakamura, Mitsuhiro; Shiinoki, Takehiro; Mizowaki, Takashi; Hiraoka, Masahiro

2012-01-01

Purpose: To identify the dosimetric parameters associated with gastrointestinal (GI) toxicity in patients with locally advanced pancreatic cancer (LAPC) treated with gemcitabine-based chemoradiotherapy. Methods and Materials: The data from 40 patients were analyzed retrospectively. Chemoradiotherapy consisted of conventional fractionated three-dimensional radiotherapy and weekly gemcitabine. Treatment-related acute GI toxicity and upper GI bleeding (UGB) were graded according to the Common Toxicity Criteria Adverse Events, version 4.0. The dosimetric parameters (mean dose, maximal absolute dose which covers 2 cm 3 of the organ, and absolute volume receiving 10–50 Gy [V 10–50 ]) of the stomach, duodenum, small intestine, and a composite structure of the stomach and duodenum (StoDuo) were obtained. The planning target volume was also obtained. Univariate analyses were performed to identify the predictive factors for the risk of grade 2 or greater acute GI toxicity and grade 3 or greater UGB, respectively. Results: The median follow-up period was 15.7 months (range, 4–37). The actual incidence of acute GI toxicity was 33%. The estimated incidence of UGB at 1 year was 20%. Regarding acute GI toxicity, a V 50 of ≥16 cm 3 of the stomach was the best predictor, and the actual incidence in patients with V 50 3 of the stomach vs. those with V 50 of ≥16 cm 3 was 9% vs. 61%, respectively (p = 0.001). Regarding UGB, V 50 of ≥33 cm 3 of the StoDuo was the best predictor, and the estimated incidence at 1 year in patients with V 50 3 of the StoDuo vs. those with V 50 ≥33 cm 3 was 0% vs. 44%, respectively (p = 0.002). The dosimetric parameters correlated highly with one another. Conclusion: The irradiated absolute volume of the stomach and duodenum are important for the risk of acute GI toxicity and UGB. These results could be helpful in escalating the radiation doses using novel techniques, such as intensity-modulated radiotherapy, for the treatment of pancreatic

Comparison of intraoperative dosimetric implant representation with postimplant dosimetry in patients receiving prostate brachytherapy.

Science.gov (United States)

Stone, Nelson N; Hong, Suzanne; Lo, Yeh-Chi; Howard, Victor; Stock, Richard G

2003-01-01

To compare the results of intraoperative dosimetry with those of CT-based postimplant dosimetry in patients undergoing prostate seed implantation. Seventy-seven patients with T1-T3 prostate cancer received an ultrasound-guided permanent seed implant (36 received (125)I, 7 (103)Pd, and 34 a partial (103)Pd implant plus external beam radiation therapy). The implantation was augmented with an intraoperative dosimetric planning system. After the peripheral needles were placed, 5-mm axial images were acquired into the treatment planning system. Soft tissue structures (prostate, urethra, and rectum) were contoured, and exact needle positions were registered. Seeds were placed with an applicator, and their positions were entered into the planning system. The dose distributions for the implant were calculated after interior needle and seed placement. Postimplant dosimetry was performed 1 month later on the basis of CT imaging. Prostate and urethral doses were compared, by using paired t tests, for the real-time dosimetry in the operating room (OR) and the postimplant dosimetry. The mean preimplant prostate volume was 39.8 cm(3), the postneedle planning volume was 41.5 cm(3) (psystem provides a close match to the actual delivered doses. These data support the use of this system to modify the implant during surgery to achieve more consistent dosimetry results.

Dosimetric benefit of adaptive re-planning in pancreatic cancer stereotactic body radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Li, Yongbao [Department of Engineering Physics, Tsinghua University, Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing (China); Center for Advanced Radiotherapy Technologies University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States); Hoisak, Jeremy D.P.; Li, Nan; Jiang, Carrie [Center for Advanced Radiotherapy Technologies University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Tian, Zhen [Center for Advanced Radiotherapy Technologies University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States); Gautier, Quentin; Zarepisheh, Masoud [Center for Advanced Radiotherapy Technologies University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Wu, Zhaoxia; Liu, Yaqiang [Department of Engineering Physics, Tsinghua University, Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing (China); Jia, Xun [Center for Advanced Radiotherapy Technologies University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States); and others

2015-01-01

Stereotactic body radiotherapy (SBRT) shows promise in unresectable pancreatic cancer, though this treatment modality has high rates of normal tissue toxicity. This study explores the dosimetric utility of daily adaptive re-planning with pancreas SBRT. We used a previously developed supercomputing online re-planning environment (SCORE) to re-plan 10 patients with pancreas SBRT. Tumor and normal tissue contours were deformed from treatment planning computed tomographies (CTs) and transferred to daily cone-beam CT (CBCT) scans before re-optimizing each daily treatment plan. We compared the intended radiation dose, the actual radiation dose, and the optimized radiation dose for the pancreas tumor planning target volume (PTV) and the duodenum. Treatment re-optimization improved coverage of the PTV and reduced dose to the duodenum. Within the PTV, the actual hot spot (volume receiving 110% of the prescription dose) decreased from 4.5% to 0.5% after daily adaptive re-planning. Within the duodenum, the volume receiving the prescription dose decreased from 0.9% to 0.3% after re-planning. It is noteworthy that variation in the amount of air within a patient's stomach substantially changed dose to the PTV. Adaptive re-planning with pancreas SBRT has the ability to improve dose to the tumor and decrease dose to the nearby duodenum, thereby reducing the risk of toxicity.

Dosimetric comparison in a cancer of the Cervix with different therapeutic modalities

International Nuclear Information System (INIS)

Alonso Iracheta, L.; Casa de Julian, M. A. de la; Samper Ots, P.; Penas Cabrera, M. D. de las; Jimenez Gonzalez, J. M.

2013-01-01

Cervical cancer is usually treated with radiotherapy composed of 3D (RC3D) and supine position, and is usually not usually outline the small intestine in cases of exclusively pelvic irradiation. In our Center we wanted to check what dose receives the small intestine in these cases and if the positioning of the patient or used irradiation technique influence the distribution of the histogram dose-volume. (Author)

Dosimetric Comparison of Helical Tomotherapy and Dynamic Conformal Arc Therapy in Stereotactic Radiosurgery for Vestibular Schwannomas

International Nuclear Information System (INIS)

Lee, Tsair-Fwu; Chao, Pei-Ju; Wang, Chang-Yu; Lan, Jen-Hong; Huang, Yu-Je; Hsu, Hsuan-Chih; Sung, Chieh-Cheng; Su, Te-Jen; Lian, Shi-Long; Fang, Fu-Min

2011-01-01

The dosimetric results of stereotactic radiosurgery (SRS) for vestibular schwannoma (VS) performed using dynamic conformal arc therapy (DCAT) with the Novalis system and helical TomoTherapy (HT) were compared using plan quality indices. The HT plans were created for 10 consecutive patients with VS previously treated with SRS using the Novalis system. The dosimetric indices used to compare the techniques included the conformity index (CI) and homogeneity index (HI) for the planned target volume (PTV), the comprehensive quality index (CQI) for nine organs at risk (OARs), gradient score index (GSI) for the dose drop-off outside the PTV, and plan quality index (PQI), which was verified using the plan quality discerning power (PQDP) to incorporate 3 plan indices, to evaluate the rival plans. The PTV ranged from 0.27-19.99 cm 3 (median 3.39 cm 3 ), with minimum required PTV prescribed doses of 10-16 Gy (median 12 Gy). Both systems satisfied the minimum required PTV prescription doses. HT conformed better to the PTV (CI: 1.51 ± 0.23 vs. 1.94 ± 0.34; p < 0.01), but had a worse drop-off outside the PTV (GSI: 40.3 ± 10.9 vs. 64.9 ± 13.6; p < 0.01) compared with DCAT. No significant difference in PTV homogeneity was observed (HI: 1.08 ± 0.03 vs. 1.09 ± 0.02; p = 0.20). HT had a significantly lower maximum dose in 4 OARs and significant lower mean dose in 1 OAR; by contrast, DCAT had a significantly lower maximum dose in 1 OAR and significant lower mean dose in 2 OARs, with the CQI of the 9 OARs = 0.92 ± 0.45. Plan analysis using PQI (HT 0.37 ± 0.12 vs. DCAT 0.65 ± 0.08; p < 0.01), and verified using the PQDP, confirmed the dosimetric advantage of HT. However, the HT system had a longer beam-on time (33.2 ± 7.4 vs. 4.6 ± 0.9 min; p < 0.01) and consumed more monitor units (16772 ± 3803 vs. 1776 ± 356.3; p < 0.01). HT had a better dose conformity and similar dose homogeneity but worse dose gradient than DCAT. Plan analysis confirmed the dosimetric advantage of HT

Dosimetric impact of systematic MLC positional errors on step and shoot IMRT for prostate cancer: a planning study

International Nuclear Information System (INIS)

Ung, N.M.; Harper, C.S.; Wee, L.

2011-01-01

Full text: The positional accuracy of multileaf collimators (MLC) is crucial in ensuring precise delivery of intensity-modulated radiotherapy (IMRT). The aim of this planning study was to investigate the dosimetric impact of systematic MLC positional errors on step and shoot IMRT of prostate cancer. A total of 12 perturbations of MLC leaf banks were introduced to six prostate IMRT treatment plans to simulate MLC systematic positional errors. Dose volume histograms (DVHs) were generated for the extraction of dose endpoint parameters. Plans were evaluated in terms of changes to the defined endpoint dose parameters, conformity index (CI) and healthy tissue avoidance (HTA) to planning target volume (PTV), rectum and bladder. Negative perturbations of MLC had been found to produce greater changes to endpoint dose parameters than positive perturbations of MLC (p 9 5 of -1.2 and 0.9% respectively. Negative and positive synchronised MLC perturbations of I mm in one direction resulted in median changes in D 9 5 of -2.3 and 1.8% respectively. Doses to rectum were generally more sensitive to systematic MLC en-ors compared to bladder (p < 0.01). Negative and positive synchronised MLC perturbations of I mm in one direction resulted in median changes in endpoint dose parameters of rectum and bladder from 1.0 to 2.5%. Maximum reduction of -4.4 and -7.3% were recorded for conformity index (CI) and healthy tissue avoidance (HT A) respectively due to synchronised MLC perturbation of 1 mm. MLC errors resulted in dosimetric changes in IMRT plans for prostate. (author)

Amorphous chalcogenide semiconductors for solid state dosimetric systems of high-energetic ionizing radiation

International Nuclear Information System (INIS)

Shpotyuk, O.

1997-01-01

The application possibilities of amorphous chalcogenide semiconductors use as radiation-sensitive elements of high-energetic (E > 1 MeV) dosimetric systems are analysed. It is shown that investigated materials are characterized by more wide region of registered absorbed doses and low temperature threshold of radiation information bleaching in comparison with well-known analogies based on coloring oxide glasses. (author)

SU-F-T-449: Dosimetric Comparison of Acuros XB, Adaptive Convolve in Intensity Modulated Radiotherapy for Head and Neck Cancer

Energy Technology Data Exchange (ETDEWEB)

Uehara, R [National Cancer Center Hospital East, Kashiwa, Chiba (Japan); Tachibana, H [National Cancer Center, Kashiwa, Chiba (Japan)

2016-06-15

Purpose: There have been several publications focusing on dose calculation in lung for a new dose calculation algorithm of Acuros XB (AXB). AXB could contribute to dose calculation for high-density media for bone and dental prosthesis rather than in lung. We compared the dosimetric performance of AXB, Adaptive Convolve (AC) in head and neck IMRT plans. Methods: In a phantom study, the difference in depth profile between AXB and AC was evaluated using Kodak EDR2 film sandwiched with tough water phantoms. 6 MV x-ray using the TrueBeam was irradiated. In a patient study, 20 head and neck IMRT plans had been clinically approved in Pinnacle3 and were transferred to Eclipse. Dose distribution was recalculated using AXB in Eclipse while maintaining AC-calculated monitor units and MLC sequence planned in Pinnacle. Subsequently, both the dose-volumetric data obtained using the two different calculation algorithms were compared. Results: The results in the phantom evaluation for the shallow area ahead of the build-up region shows over-dose for AXB and under-dose for AC, respectively. In the patient plans, AXB shows more hot spots especially around the high-density media than AC in terms of PTV (Max difference: 4.0%) and OAR (Max. difference: 1.9%). Compared to AC, there were larger dose deviations in steep dose gradient region and higher skin-dose. Conclusion: In head and neck IMRT plans, AXB and AC show different dosimetric performance for the regions inside the target volume around high-density media, steep dose gradient regions and skin-surface. There are limitations in skin-dose and complex anatomic condition using even inhomogeneous anthropomorphic phantom Thus, there is the potential for an increase of hot-spot in AXB, and an underestimation of dose in substance boundaries and skin regions in AC.

SU-F-T-449: Dosimetric Comparison of Acuros XB, Adaptive Convolve in Intensity Modulated Radiotherapy for Head and Neck Cancer

International Nuclear Information System (INIS)

Uehara, R; Tachibana, H

2016-01-01

Purpose: There have been several publications focusing on dose calculation in lung for a new dose calculation algorithm of Acuros XB (AXB). AXB could contribute to dose calculation for high-density media for bone and dental prosthesis rather than in lung. We compared the dosimetric performance of AXB, Adaptive Convolve (AC) in head and neck IMRT plans. Methods: In a phantom study, the difference in depth profile between AXB and AC was evaluated using Kodak EDR2 film sandwiched with tough water phantoms. 6 MV x-ray using the TrueBeam was irradiated. In a patient study, 20 head and neck IMRT plans had been clinically approved in Pinnacle3 and were transferred to Eclipse. Dose distribution was recalculated using AXB in Eclipse while maintaining AC-calculated monitor units and MLC sequence planned in Pinnacle. Subsequently, both the dose-volumetric data obtained using the two different calculation algorithms were compared. Results: The results in the phantom evaluation for the shallow area ahead of the build-up region shows over-dose for AXB and under-dose for AC, respectively. In the patient plans, AXB shows more hot spots especially around the high-density media than AC in terms of PTV (Max difference: 4.0%) and OAR (Max. difference: 1.9%). Compared to AC, there were larger dose deviations in steep dose gradient region and higher skin-dose. Conclusion: In head and neck IMRT plans, AXB and AC show different dosimetric performance for the regions inside the target volume around high-density media, steep dose gradient regions and skin-surface. There are limitations in skin-dose and complex anatomic condition using even inhomogeneous anthropomorphic phantom Thus, there is the potential for an increase of hot-spot in AXB, and an underestimation of dose in substance boundaries and skin regions in AC.

SU-E-T-311: Dosimetric Comparison of Volumetric Modulated Arc Therapy Plans for Preoperative Radiotherapy Rectal Cancer Using Flattening Filter-Free and Flattening Filter Modes

Energy Technology Data Exchange (ETDEWEB)

Zhang, W; Zhang, J; Lu, J; Chen, C [Cancer Hospital of Shantou University Medical College, Shantou, Guangdong (China)

2015-06-15

Purpose: To compare the dosimetric difference of volumetric modulated arc therapy(VMAT) for preoperative radiotherapy rectal cancer using 6MV X-ray flattening filter free(FFF) and flattening filter(FF) modes. Methods: FF-VMAT and FFF-VMAT plans were designed to 15 rectal cancer patients with preoperative radiotherapy by planning treatment system(Eclipse 10.0),respectively. Dose prescription was 50 Gy in 25 fractions. All plans were normalized to 50 Gy to 95% of PTV. The Dose Volume Histogram (DVH), target and risk organ doses, conformity indexes (CI), homogeneity indexes (HI), low dose volume of normal tissue(BP), monitor units(MU) and treatment time (TT) were compared between the two kinds of plans. Results: FF-VMAT provided the lower Dmean, V105, HI, and higher CI as compared with FFF-VMAT. The small intestine of D5, Bladder of D5, Dmean, V40, V50, L-femoral head of V40, R-femoral head of Dmean were lower in FF-VMAT than in FFF-VMAT. FF-VMAT had higher BP of V5, but no significantly different of V10, V15, V20, V30 as compared with FFF-VMAT. FF-VMAT reduceed the monitor units(MU) by 21%(P<0.05), as well as the treatment time(TT) was no significantly different(P>0.05), as compared with FFF-VMAT. Conclusion: The plan qualities of FF and FFF VMAT plans were comparable and both clinically acceptable. FF-VMAT as compared with FFF-VMAT, showing better target coverage, some of OARs sparing, the MUs of FFF-VMAT were higher than FF-VMAT, yet were delivered within the same time. This work was supported by the Medical Scientific Research Foundation of Guangdong Procvince (A2014455 to Changchun Ma)

Anatomic and dosimetric changes in patients with head and neck cancer treated with an integrated MRI-tri-60Co teletherapy device.

Science.gov (United States)

Raghavan, Govind; Kishan, Amar U; Cao, Minsong; Chen, Allen M

2016-11-01

Prior studies have relied on CT to assess alterations in anatomy among patients undergoing radiation for head and neck cancer. We sought to determine the feasibility of using MRI-based image-guided radiotherapy to quantify these changes and to ascertain their potential dosimetric implications. 6 patients with head and neck cancer were treated with intensity-modulated radiotherapy (IMRT) on a novel tri- 60 Co teletherapy system equipped with a 0.35-T MRI (VR, ViewRay Incorporated, Oakwood Village, OH) to 66-70 Gy in 33 fractions (fx). Pre-treatment MRIs on Fx 1, 5, 10, 15, 20, 25, 30 and 33 were imported into a contouring interface, where the primary gross tumour volume (GTV) and parotid glands were delineated. The centre of mass (COM) shifts for these structures were assessed relative to Day 1. Dosimetric data were co-registered with the MRIs, and doses to the GTV and parotid glands were assessed. Primary GTVs decreased significantly over the course of IMRT (median % volume loss, 38.7%; range, 29.5-72.0%; p < 0.05) at a median rate of 1.2%/fx (range, 0.92-2.2%/fx). Both the ipsilateral and contralateral parotid glands experienced significant volume loss (p < 0.05, for all) and shifted medially during IMRT. Weight loss correlated significantly with parotid gland volume loss and medial COM shift (p < 0.05). Integrated on-board MRI can be used to accurately contour and analyze primary GTVs and parotid glands over the course of IMRT. COM shifts and significant volume reductions were observed, confirming the results of prior CT-based exercises. Advances in knowledge: The superior resolution of on-board MRI may facilitate online adaptive replanning in the future.

SU-E-T-538: Lung SBRT Dosimetric Comparison of 3D Conformal and RapidArc Planning

International Nuclear Information System (INIS)

Jiang, R; Zhan, L; Osei, E

2015-01-01

Purpose: Dose distributions of RapidArc Plan can be quite different from standard 3D conformal radiation therapy. SBRT plans can be optimized with high conformity or mimic the 3D conformal treatment planning with very high dose in the center of the tumor. This study quantifies the dosimetric differences among 3D conformal plan; flattened beam and FFF beam RapidArc Plans for lung SBRT. Methods: Five lung cancer patients treated with 3D non-coplanar SBRT were randomly selected. All the patients were CT scanned with 4DCT to determine the internal target volume. Abdominal compression was applied to minimize respiratory motion for SBRT patients. The prescription dose was 48 Gy in 4 fractions. The PTV coverage was optimized by two groups of objective function: one with high conformity, another mimicking 3D conformal dose distribution with high dose in the center of PTV. Optimization constraints were set to meet the criteria of the RTOG-0915 protocol. All VMAT plans were optimized with the RapidArc technique using four full arcs in Eclipse treatment planning system. The RapidArc SBRT plans with flattened 6MV beam and 6MV FFF beam were generated and dosimetric results were compared with the previous treated 3D non-coplanar plans. Results: All the RapidArc plans with flattened beam and FFF beam had similar results for the PTV and OARs. For the high conformity optimization group, The DVH of PTV exhibited a steep dose fall-off outside the PTV compared to the 3D non-coplanar plan. However, for the group mimicking the 3D conformal target dose distribution, although the PTV is very similar to the 3D conformal plan, the ITV coverage is better than 3D conformal plan. Conclusion: Due to excellent clinical experiences of 3D conformal SBRT treatment, the Rapid Arc optimization mimicking 3D conformal planning may be suggested for clinical use

Measurements of air kerma index in computed tomography: a comparison among methodologies

International Nuclear Information System (INIS)

Alonso, T. C.; Mourao, A. P.; Da Silva, T. A.

2016-10-01

Computed tomography (CT) has become the most important and widely used technique for diagnosis purpose. As CT exams impart high doses to patients in comparison to other radiologist techniques, reliable dosimetry is required. Dosimetry in CT is done in terms of air kerma index in air or in a phantom measured by a pencil ionization chamber under a single X-ray tube rotation. In this work, a comparison among CT dosimetric quantities measured by an UNFORS pencil ionization chamber, MTS-N RADOS thermoluminescent dosimeters and GAFCHROMIC XR-CT radiochromic film was done. The three dosimetric systems were properly calibrated in X-ray reference radiations in a calibration laboratory. CT dosimetric quantities were measured in CT Bright Speed GE Medical Systems Inc., scanner in a PMMA trunk phantom and a comparison among the three dosimetric techniques was done. (Author)

Measurements of air kerma index in computed tomography: a comparison among methodologies

Energy Technology Data Exchange (ETDEWEB)

Alonso, T. C.; Mourao, A. P.; Da Silva, T. A., E-mail: alonso@cdtn.br [Universidade Federal de Minas Gerais, Programa de Ciencia y Tecnicas Nucleares, Av. Pres. Antonio Carlos 6627, Pampulha, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

2016-10-15

Computed tomography (CT) has become the most important and widely used technique for diagnosis purpose. As CT exams impart high doses to patients in comparison to other radiologist techniques, reliable dosimetry is required. Dosimetry in CT is done in terms of air kerma index in air or in a phantom measured by a pencil ionization chamber under a single X-ray tube rotation. In this work, a comparison among CT dosimetric quantities measured by an UNFORS pencil ionization chamber, MTS-N RADOS thermoluminescent dosimeters and GAFCHROMIC XR-CT radiochromic film was done. The three dosimetric systems were properly calibrated in X-ray reference radiations in a calibration laboratory. CT dosimetric quantities were measured in CT Bright Speed GE Medical Systems Inc., scanner in a PMMA trunk phantom and a comparison among the three dosimetric techniques was done. (Author)

SU-F-SPS-10: The Dosimetric Comparison of GammaKnife and Cyberknife Treatment Plans for Brain SRS Treatment

International Nuclear Information System (INIS)

Sanli, E; Mabhouti, H; Cebe, M; Codel, G; Pacaci, P; Serin, E; Kucuk, N; Kucukmorkoc, E; Doyuran, M; Canoglu, D; Altinok, A; Acar, H; Caglar Ozkok, H

2016-01-01

Purpose: Brain stereotactic radiosurgery (SRS) involves the use of precisely directed, single session radiation to create a desired radiobiologic response within the brain target with acceptable minimal effects on surrounding structures or tissues. In this study, the dosimetric comparison of GammaKnife perfection and Cyberknife M6 treatment plans were made. Methods: Treatment plannings were done for GammaKnife perfection unit using Gammaplan treatment planning system (TPS) on the CT scan of head and neck randophantom simulating the treatment of sterotactic treatments for one brain metastasis. The dose distribution were calculated using TMR 10 algorithm. The treatment planning for the same target were also done for Cyberknife M6 machine using Multiplan (TPS) with Monte Carlo algorithm. Using the same film batch, the net OD to dose calibration curve was obtained using both machine by delivering 0- 800 cGy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution were measured using EBT3 film dosimeter. The measured and calculated doses were compared. Results: The dose distribution in the target and 2 cm beyond the target edge were calculated on TPSs and measured using EBT3 film. For cyberknife treatment plans, the gamma analysis passing rates between measured and calculated dose distributions were 99.2% and 96.7% for target and peripheral region of target respectively. For gammaknife treatment plans, the gamma analysis passing rates were 98.9% and 93.2% for target and peripheral region of target respectively. Conclusion: The study shows that dosimetrically comparable plans are achievable with Cyberknife and GammaKnife. Although TMR 10 algorithm predicts the target dose

SU-F-SPS-10: The Dosimetric Comparison of GammaKnife and Cyberknife Treatment Plans for Brain SRS Treatment

Energy Technology Data Exchange (ETDEWEB)

Sanli, E; Mabhouti, H; Cebe, M; Codel, G; Pacaci, P; Serin, E; Kucuk, N; Kucukmorkoc, E; Doyuran, M; Canoglu, D; Altinok, A; Acar, H; Caglar Ozkok, H [Medipol University, Istanbul, Istanbul (Turkey)

2016-06-15

Purpose: Brain stereotactic radiosurgery (SRS) involves the use of precisely directed, single session radiation to create a desired radiobiologic response within the brain target with acceptable minimal effects on surrounding structures or tissues. In this study, the dosimetric comparison of GammaKnife perfection and Cyberknife M6 treatment plans were made. Methods: Treatment plannings were done for GammaKnife perfection unit using Gammaplan treatment planning system (TPS) on the CT scan of head and neck randophantom simulating the treatment of sterotactic treatments for one brain metastasis. The dose distribution were calculated using TMR 10 algorithm. The treatment planning for the same target were also done for Cyberknife M6 machine using Multiplan (TPS) with Monte Carlo algorithm. Using the same film batch, the net OD to dose calibration curve was obtained using both machine by delivering 0- 800 cGy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution were measured using EBT3 film dosimeter. The measured and calculated doses were compared. Results: The dose distribution in the target and 2 cm beyond the target edge were calculated on TPSs and measured using EBT3 film. For cyberknife treatment plans, the gamma analysis passing rates between measured and calculated dose distributions were 99.2% and 96.7% for target and peripheral region of target respectively. For gammaknife treatment plans, the gamma analysis passing rates were 98.9% and 93.2% for target and peripheral region of target respectively. Conclusion: The study shows that dosimetrically comparable plans are achievable with Cyberknife and GammaKnife. Although TMR 10 algorithm predicts the target dose.

Dosimetric pre-treatment verification of IMRT using an EPID; clinical experience

International Nuclear Information System (INIS)

Zijtveld, Mathilda van; Dirkx, Maarten L.P.; Boer, Hans C.J. de; Heijmen, Ben J.M.

2006-01-01

Background and purpose: In our clinic a QA program for IMRT verification, fully based on dosimetric measurements with electronic portal imaging devices (EPID), has been running for over 3 years. The program includes a pre-treatment dosimetric check of all IMRT fields. During a complete treatment simulation at the linac, a portal dose image (PDI) is acquired with the EPID for each patient field and compared with a predicted PDI. In this paper, the results of this pre-treatment procedure are analysed, and intercepted errors are reported. An automated image analysis procedure is proposed to limit the number of fields that need human intervention in PDI comparison. Materials and methods: Most of our analyses are performed using the γ index with 3% local dose difference and 3 mm distance to agreement as reference values. Scalar parameters are derived from the γ values to summarize the agreement between measured and predicted 2D PDIs. Areas with all pixels having γ values larger than one are evaluated, making decisions based on clinically relevant criteria more straightforward. Results: In 270 patients, the pre-treatment checks revealed four clinically relevant errors. Calculation of statistics for a group of 75 patients showed that the patient-averaged mean γ value inside the field was 0.43 ± 0.13 (1 SD) and only 6.1 ± 6.8% of pixels had a γ value larger than one. With the proposed automated image analysis scheme, visual inspection of images can be avoided in 2/3 of the cases. Conclusion: EPIDs may be used for high accuracy and high resolution routine verification of IMRT fields to intercept clinically relevant dosimetric errors prior to the start of treatment. For the majority of fields, PDI comparison can fully rely on an automated procedure, avoiding excessive workload

Quantitative comparison of volumetric modulated arc therapy and intensity modulated radiotherapy plan quality in sino-nasal cancer

International Nuclear Information System (INIS)

Sankaralingam, Marimuthu; Glegg, Martin; Smith, Suzanne; James, Allan; Rizwanullah, Mohammed

2012-01-01

The aim of this study was to compare various dosimetric parameters of dynamic mlc intensity modulated radiotherapy (IMRT) plans with volumetric modulated arc therapy (VMAT) plans for sino-nasal cancers, which are rare and complex tumors to treat with radiotherapy. IMRT using five fields, coplanar in the sagittal plane and VMAT employing two coplanar arc plans were created for five patients. The plans were assessed by comparing Conformity Index and Sigma Index (dose homogeneity) in the Planning Target Volume (PTV) and through comparison of dose-volume characteristics to the following organs at risk (OARs): Spinal cord, brainstem, eye, ipsilateral and contralateral optic nerve and the volume of brain receiving 10% of the prescribed dose (V 10% ). The total monitor units required to deliver the plan were also compared. Conformity Index was found to be superior in VMAT plans for three patients and in IMRT plans for two patients. Dose homogeneity within the PTV was better with VMAT plans for all five cases. The mean difference in Sigma Index was 0.68%. There was no significant difference in dose between IMRT and VMAT plans for any of the OARs assessed in these patients. The monitor units were significantly reduced in the VMAT plan in comparison to the IMRT plan for four out of five patients, with mean reduction of 66%. It was found in this study that for the treatment of sino-nasal cancer, VMAT produced minimal, and statistically insignificant improvement in dose homogeneity within the PTV when compared with IMRT. VMAT plans were delivered using significantly fewer monitor units. We conclude in this study that VMAT does not offer significant improvement of treatment for sino-nasal cancer over the existing IMRT techniques, but the findings may change with a larger sample of patients in this rare condition. (author)

Amorphous chalcogenide semiconductors for solid state dosimetric systems of high-energetic ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Shpotyuk, O. [Pedagogical University, Czestochowa (Poland)]|[Institute of Materials, Lvov (Ukraine)

1997-12-31

The application possibilities of amorphous chalcogenide semiconductors use as radiation-sensitive elements of high-energetic (E > 1 MeV) dosimetric systems are analysed. It is shown that investigated materials are characterized by more wide region of registered absorbed doses and low temperature threshold of radiation information bleaching in comparison with well-known analogies based on coloring oxide glasses. (author). 16 refs, 1 tab.

Cancer of the uterine cervix: dosimetric guidelines for prevention of late rectal and rectosigmoid complications as a result of radiotherapeutic treatment

International Nuclear Information System (INIS)

Pourquier, H.; Dubois, J.B.; Delard, R.

1982-01-01

This paper is the report of a dosimetric study of 41 rectal and rectosigmoid complications after radiotherapeutic treatment (1974-1978) of 287 cervical uterine tumors. Treatment consisted of external irradiation (25 MeV linear accelerator) and intracavitary irradiation (Fletcher-Suit applicator) at different doses depending on tumor stage. Dosimetric measurements were expressed as the maximum rectal dose and mean rectal dose on the anterior surface of the rectum, as proposed by the Groupe Europeen de Curietherapie. Rectal doses were also studied as a function of intracavitary irradiation and intracavitary + external irradiation (maximum rectal and mean cummulative doses for each). The results show a significant difference in the state of the patients with and without complications, based on the dose reaching the rectum. The maximum and the mean cumulative rectal doses serve as one of the primary indicators for predicting complications. These values should therefore be determined before placement of intracavitary sources or, at the latest, before the second intracavitary applications. We have shown that there is no fixed threshold dose, but that it varies from one region to another, depending on level of external irradiation. Our results argue in favor of adapting individual patient therapy based on simple precautions, which are adjustable to all treatment modalities. This method could lead to complete elimination of late rectal and rectosigmoid complications arising from radiotherapeutic treatment of cervical uterine cancer

Correlations of post-implant regional dosimetric parameters at 24 hours and one month, with clinical results of low-dose-rate brachytherapy for localized prostate cancer

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Eiichiro Okazaki

2017-12-01

Full Text Available Purpose : To evaluate the correlations of post-implant regional dosimetrics at 24 hours (24 h and 1 month after implant procedures, with clinical outcomes of low-dose-rate (LDR brachytherapy for localized prostate cancer. Material and methods : Between January 2008 and December 2014, 130 consecutive patients treated for localized prostate cancer, receiving definitive iodine-125 ( 125 I brachytherapy treatment were retrospectively analyzed. All patients underwent post-implant CT imaging for dosimetric analysis at 24 h and 1 month after implantation procedure. Prostate contours were divided into quadrants: anterior-superior (ASQ, posterior-superior (PSQ, anterior-inferior (AIQ, and posterior-inferior (PIQ. Predictive factors and cut-off values of biochemical failure-free survival (BFFS and toxicities of LDR brachytherapy were analyzed. Results : The median follow-up time was 69.5 months. Seven patients (5.4% had biochemical failure. The 3-year and 5-year BFFS rates were 96.7% and 93.1%, respectively. On multivariate analysis, prostate-specific antigen and Gleason score were significant prognostic factors for biochemical failure. D 90 (the minimal dose received by 90% of the volume of PSQ and PIQ at 24 h, and D 90 of PSQ at 1 month were also significant factors. The cut-off values of PSQ D 90 were 145 Gy at 24 h and 160 Gy at 1 month. D 90 of the whole prostate was not significant at 24 h and at 1 month. D 90 of PSQ at 1 month was a significant factor for rectal hemorrhage. Conclusions : Post-implant D 90 of PSQ is significantly associated with BFFS for localized prostate cancer not only at 1 month, but also at 24 hours. D 90 of PSQ at 1 month is also a significant factor for rectal hemorrhage.

Dosimetric evaluation of simultaneous integrated boost during stereotactic body radiation therapy for pancreatic cancer

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Yang, Wensha, E-mail: wensha.yang@cshs.org [Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, CA (United States); Reznik, Robert; Fraass, Benedick A. [Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, CA (United States); Nissen, Nicholas [Department of Surgery, Cedars Sinai Medical Center, Los Angeles, CA (United States); Hendifar, Andrew [Department of Gastrointestinal Oncology, Cedars Sinai Medical Center, Los Angeles, CA (United States); Wachsman, Ashley [Department of Cross-Sectional Imaging Interventional Oncology, Cedars Sinai Medical Center, Los Angeles, CA (United States); Sandler, Howard; Tuli, Richard [Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, CA (United States)

2015-04-01

Stereotactic body radiation therapy (SBRT) provides a promising way to treat locally advanced pancreatic cancer and borderline resectable pancreatic cancer. A simultaneous integrated boost (SIB) to the region of vessel abutment or encasement during SBRT has the potential to downstage otherwise likely positive surgical margins. Despite the potential benefit of using SIB-SBRT, the ability to boost is limited by the local geometry of the organs at risk (OARs), such as stomach, duodenum, and bowel (SDB), relative to tumor. In this study, we have retrospectively replanned 20 patients with 25 Gy prescribed to the planning target volume (PTV) and 33~80 Gy to the boost target volume (BTV) using an SIB technique for all patients. The number of plans and patients able to satisfy a set of clinically established constraints is analyzed. The ability to boost vessels (within the gross target volume [GTV]) is shown to correlate with the overlap volume (OLV), defined to be the overlap between the GTV + a 1(OLV1)- or 2(OLV2)-cm margin with the union of SDB. Integral dose, boost dose contrast (BDC), biologically effective BDC, tumor control probability for BTV, and normal tissue complication probabilities are used to analyze the dosimetric results. More than 65% of the cases can deliver a boost to 40 Gy while satisfying all OAR constraints. An OLV2 of 100 cm{sup 3} is identified as the cutoff volume: for cases with OLV2 larger than 100 cm{sup 3}, it is very unlikely the case could achieve 25 Gy to the PTV while successfully meeting all the OAR constraints.

SU-F-J-124: Reduction in Dosimetric Impact of Motion Using VMAT Compared to IMRT in Hypofractionated Prostate Cancer Patients

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Ravindranath, B; Xiong, J; Happersett, L; Mageras, G; Zhang, P; Hunt, M [Memorial Sloan Kettering Cancer Center, New York, NY (United States)

2016-06-15

Purpose: To quantify and compare the dosimetric impact of motion management correction strategies during VMAT and IMRT for hypofractionated prostate treatment. Methods: Two arc VMAT and 9 field IMRT plans were generated for two prostate cancer patients undergoing hypofractionated radiotherapy (7.5Gy × 5 and 8Gy × 5). 212 motion traces were retrospectively extracted from treatment records of prostate cancer patients with implanted Calypso beacons. Dose to the CTV and normal tissues was reconstructed for each trace and plan taking into account the actual treatment delivery time. Following motion correction scenarios were simulated: (1) VMAT plan – (a) No correction, (b) correction between arcs, (c) correction every 20 degrees of gantry rotation and (2) IMRT plan - (a) No correction,(b) correction between fields. Two mm action threshold for position correction was assumed. The 5–95% confidence interval (CI) range was extracted from the family of DVHs for each correction scenario. Results: Treatment duration for 8Gy plan (VMAT vs IMRT) was 3 vs 12 mins and for 7.5Gy plan was 3 vs 9 mins. In the absence of correction, the VMAT 5–−95% CI dose spread was, on average, less than the IMRT dose spread by 2% for CTVD95, 9% for rectalwall (RW) D1cc and 9% for bladderwall (BW) D53. Further, VMAT b/w arcs correction strategy reduced the spread about the planned value compared to IMRT b/w fields correction by: 1% for CTVD95, 2.6% for RW1cc and 2% for BWD53. VMAT 20 degree strategy led to greater reduction in dose spread compared to IMRT by: 2% for CTVD95, 4.5% for RW1cc and 6.7% for BWD53. Conclusion: In the absence of a correction strategy, the limited motion during VMAT’s shorter delivery times translates into less motion-induced dosimetric degradation than IMRT. Performing limited periodic motion correction during VMAT can yield excellent conformity to planned values that is superior to IMRT. This work was partially supported by Varian Medical Systems.

A comparative dosimetric study of conventional, conformal and intensity-modulated radiotherapy in postoperative pelvic irradiation of cervical cancer

International Nuclear Information System (INIS)

Li Bin; An Jusheng; Wu Lingying; Huang Manni; Gao Juzhen; Xu Yingjie; Dai Jianrong

2008-01-01

Objective: To evaluate target-volume coverage and organ at risk (OAR) protection achieved with conventional radiotherapy (CRT), three dimensional conformal radiotherapy (3DCRT), and intensity-modulated radiotherapy(IMRT) through dosimetric comparison in patients with cervical cancer after hysterectomy. Methods: The planning CT scans of 10 patients treated with pelvic radiation after hysterectomy for cervical cancer were used to generate CRT, 3DCRT and IMRT plans for this study. Clinical target volume(CTV) was contoured on the individual axial CT slices of every patient. The CTV was then uniformly expanded by 1.0 cm to create the planning target volume (PTV). The small bowel, rectum, bladder, bone marrow, ovaries, and femoral heads were outlined for the organ at risk (OAR) evaluation. The CRT, 3DCRT and IMRT plans were generated using commercial planning software. CRT plan was prescribed to deliver 45 Gy to the reference point, while IMRT and 3DCRT plans were 45 Gy to 95% of the PTV. Isodose line and dose volume histograms(DVH) were used to evaluate the dose distribution in CTV and OAR. Results: For 10 patients, the average volume of CTV receiving the prescribed dose of CRT was significantly lower than 3DCRT(Q=8.27, P<0.01) and IMRT(Q=8.37, P<0.01), respectively. Comparing with the CRT plan, the 3DCRT and IMRT plans notably reduced the volume of bowel at 30 and 45 Gy levels. The IMRT plan significantly spared rectum and bladder at 30 and 45 Gy levels comparing with the CRT (P<0.01) and 3DCRT(P<0.05) plans, while the 3DCRT plan significantly spared rectum and bladder at 45 Gy level comparing with the CRT(P<0.01) plans. For 4 patients with ovarian transposition, the average doses of ovary over 3 Gy were 2 patients with the 3 DCRT and IMRT plans, and 2 with all three plans. Conclusions: IMRT and 3DCRT are superior to CRT in improving dose coverage of target volume and sparing of OAR, while IMRT being the best. The superiority of IMRT and 3DCRT is obvious in sparing

Pencil beam scanning proton therapy vs rotational arc radiation therapy: A treatment planning comparison for postoperative oropharyngeal cancer

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Apinorasethkul, Ontida, E-mail: Ontida.a@gmail.com; Kirk, Maura; Teo, Kevin; Swisher-McClure, Samuel; Lukens, John N.; Lin, Alexander

2017-04-01

Patients diagnosed with head and neck cancer are traditionally treated with photon radiotherapy. Proton therapy is currently being used clinically and may potentially reduce treatment-related toxicities by minimizing the dose to normal organs in the treatment of postoperative oropharyngeal cancer. The finite range of protons has the potential to significantly reduce normal tissue toxicity compared to photon radiotherapy. Seven patients were planned with both proton and photon modalities. The planning goal for both modalities was achieving the prescribed dose to 95% of the planning target volume (PTV). Dose-volume histograms were compared in which all cases met the target coverage goals. Mean doses were significantly lower in the proton plans for the oral cavity (1771 cGy photon vs 293 cGy proton, p < 0.001), contralateral parotid (1796 cGy photon vs 1358 proton, p < 0.001), and the contralateral submandibular gland (3608 cGy photon vs 3251 cGy proton, p = 0.03). Average total integral dose was 9.1% lower in proton plans. The significant dosimetric sparing seen with proton therapy may lead to reduced side effects such as pain, weight loss, taste changes, and dry mouth. Prospective comparisons of protons vs photons for disease control, toxicity, and patient-reported outcomes are therefore warranted and currently being pursued.

Analysis of Dosimetric Parameters Associated With Acute Gastrointestinal Toxicity and Upper Gastrointestinal Bleeding in Locally Advanced Pancreatic Cancer Patients Treated With Gemcitabine-Based Concurrent Chemoradiotherapy

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Nakamura, Akira [Department of Radiation Oncology and Image-Applied Therapy, Kyoto University Graduate School of Medicine, Kyoto (Japan); Shibuya, Keiko, E-mail: kei@kuhp.kyoto-u.ac.jp [Department of Radiation Oncology and Image-Applied Therapy, Kyoto University Graduate School of Medicine, Kyoto (Japan); Matsuo, Yukinori; Nakamura, Mitsuhiro; Shiinoki, Takehiro; Mizowaki, Takashi; Hiraoka, Masahiro [Department of Radiation Oncology and Image-Applied Therapy, Kyoto University Graduate School of Medicine, Kyoto (Japan)

2012-10-01

Purpose: To identify the dosimetric parameters associated with gastrointestinal (GI) toxicity in patients with locally advanced pancreatic cancer (LAPC) treated with gemcitabine-based chemoradiotherapy. Methods and Materials: The data from 40 patients were analyzed retrospectively. Chemoradiotherapy consisted of conventional fractionated three-dimensional radiotherapy and weekly gemcitabine. Treatment-related acute GI toxicity and upper GI bleeding (UGB) were graded according to the Common Toxicity Criteria Adverse Events, version 4.0. The dosimetric parameters (mean dose, maximal absolute dose which covers 2 cm{sup 3} of the organ, and absolute volume receiving 10-50 Gy [V{sub 10-50}]) of the stomach, duodenum, small intestine, and a composite structure of the stomach and duodenum (StoDuo) were obtained. The planning target volume was also obtained. Univariate analyses were performed to identify the predictive factors for the risk of grade 2 or greater acute GI toxicity and grade 3 or greater UGB, respectively. Results: The median follow-up period was 15.7 months (range, 4-37). The actual incidence of acute GI toxicity was 33%. The estimated incidence of UGB at 1 year was 20%. Regarding acute GI toxicity, a V{sub 50} of {>=}16 cm{sup 3} of the stomach was the best predictor, and the actual incidence in patients with V{sub 50} <16 cm{sup 3} of the stomach vs. those with V{sub 50} of {>=}16 cm{sup 3} was 9% vs. 61%, respectively (p = 0.001). Regarding UGB, V{sub 50} of {>=}33 cm{sup 3} of the StoDuo was the best predictor, and the estimated incidence at 1 year in patients with V{sub 50} <33 cm{sup 3} of the StoDuo vs. those with V{sub 50} {>=}33 cm{sup 3} was 0% vs. 44%, respectively (p = 0.002). The dosimetric parameters correlated highly with one another. Conclusion: The irradiated absolute volume of the stomach and duodenum are important for the risk of acute GI toxicity and UGB. These results could be helpful in escalating the radiation doses using novel

SU-E-P-58: Dosimetric Study of Conventional Intensity-Modulated Radiotherapy and Knowledge-Based Radiation Therapy for Postoperation of Cervix Cancer

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Ma, C; Yin, Y [Shandong Tumor Hospital, Jinan, Shandong Provice (China)

2015-06-15

Purpose: To compare the dosimetric difference of the target volume and organs at risk(OARs) between conventional intensity-modulated radiotherapy(C-IMRT) and knowledge-based radiation therapy (KBRT) plans for cervix cancer. Methods: 39 patients with cervical cancer after surgery were randomly selected, 20 patient plans were used to create the model, the other 19 cases used for comparative evaluation. All plans were designed in Eclipse system. The prescription dose was 30.6Gy, 17 fractions, OARs dose satisfied to the clinical requirement. A paired t test was used to evaluate the differences of dose-volume histograms (DVH). Results: Comparaed to C-IMRT plan, the KBRT plan target can achieve the similar target dose coverage, D98,D95,D2,HI and CI had no difference (P≥0.05). The dose of rectum, bladder and femoral heads had no significant differences(P≥0.05). The time was used to design treatment plan was significant reduced. Conclusion: This study shows that postoperative radiotherapy of cervical KBRT plans can achieve the similar target and OARs dose, but the shorter designing time.

A Comparison of Helical Intensity-Modulated Radiotherapy, Intensity-Modulated Radiotherapy, and 3D-Conformal Radiation Therapy for Pancreatic Cancer

International Nuclear Information System (INIS)

Poppe, Matthew M.; Narra, Venkat; Yue, Ning J.; Zhou Jinghao; Nelson, Carl; Jabbour, Salma K.

2011-01-01

We assessed dosimetric differences in pancreatic cancer radiotherapy via helical intensity-modulated radiotherapy (HIMRT), linac-based IMRT, and 3D-conformal radiation therapy (3D-CRT) with regard to successful plan acceptance and dose to critical organs. Dosimetric analysis was performed in 16 pancreatic cases that were planned to 54 Gy; both post-pancreaticoduodenectomy (n = 8) and unresected (n = 8) cases were compared. Without volume modification, plans met constraints 75% of the time with HIMRT and IMRT and 13% with 3D-CRT. There was no statistically significantly improvement with HIMRT over conventional IMRT in reducing liver V35, stomach V45, or bowel V45. HIMRT offers improved planning target volume (PTV) dose homogeneity compared with IMRT, averaging a lower maximum dose and higher volume receiving the prescription dose (D100). HIMRT showed an increased mean dose over IMRT to bowel and liver. Both HIMRT and IMRT offer a statistically significant improvement over 3D-CRT in lowering dose to liver, stomach, and bowel. The results were similar for both unresected and resected patients. In pancreatic cancer, HIMRT offers improved dose homogeneity over conventional IMRT and several significant benefits to 3D-CRT. Factors to consider before incorporating IMRT into pancreatic cancer therapy are respiratory motion, dose inhomogeneity, and mean dose.

SU-G-TeP3-11: Radiobiological-Cum-Dosimetric Quality Assurance of Complex Radiotherapy Plans

Energy Technology Data Exchange (ETDEWEB)

Paudel, N; Narayanasamy, G; Zhang, X; Penagaricano, J; Morrill, S [University of Arkansas for Medical Sciences, Little Rock, AR (United States); Mavroidis, P [University North Carolina, Chapel Hill, NC (United States); Pyakuryal, A [National Cancer Institute, Rockville, MD (United States); Han, E [UT MD Anderson Cancer Center, Houston, TX (United States); Liang, X [University of Florida Health Proton Therapy Institute, Jacksonville, FL (United States); Kim, D [Kyung Hee University Hospital, Seol (Korea, Republic of)

2016-06-15

Purpose: Dosimetric gamma-analysis used for QA of complex radiotherapy plans tests the dosimetric equivalence of a delivered plan with the treatment planning system (TPS) optimized plan. It does not examine whether a dosimetric difference results in any radiobiological difference. This study introduces a method to test the radiobiological and dosimetric equivalence between a delivered and the TPS optimized plan. Methods: Six head and neck and seven lung cancer VMAT or IMRT plans optimized for patient treatment were calculated and delivered to an ArcCheck phantom. ArcCheck measured dose distributions were compared with the TPS calculated dose distributions using a 2-D gamma-analysis. Dose volume histograms (DVHs) for various patient structures were obtained by using measured data in 3DVH software and compared against the TPS calculated DVHs using 3-D gamma analysis. DVH data were used in the Poisson model to calculate tumor control probability (TCP) for the treatment targets and in the sigmoid dose response model to calculate normal tissue complication probability (NTCP) for the normal structures. Results: Two-D and three-D gamma passing rates among six H&N patient plans differed by 0 to 2.7% and among seven lung plans by 0.1 to 4.5%. Average ± SD TCPs based on measurement and TPS were 0.665±0.018 and 0.674±0.044 for H&N, and 0.791±0.027 and 0.733±0.031 for lung plans, respectively. Differences in NTCPs were usually negligible. The differences in dosimetric results, TCPs and NTCPs were insignificant. Conclusion: The 2-D and 3-D gamma-analysis based agreement between measured and planned dose distributions may indicate their dosimetric equivalence. Small and insignificant differences in TCPs and NTCPs based on measured and planned dose distributions indicate the radiobiological equivalence between the measured and optimized plans. However, patient plans showing larger differences between 2-D and 3-D gamma-analysis can help us make a more definite conclusion

Life-Time Dosimetric Assessment for Mice and Rats Exposed in Reverberation Chambers of the 2-Year NTP Cancer Bioassay Study on Cell Phone Radiation.

Science.gov (United States)

Gong, Yijian; Capstick, Myles; Kuehn, Sven; Wilson, Perry; Ladbury, John; Koepke, Galen; McCormick, David L; Melnick, Ronald L; Kuster, Niels

2017-12-01

In this paper, we present the detailed life-time dosimetry analysis for rodents exposed in the reverberation exposure system designed for the two-year cancer bioassay study conducted by the National Toxicology Program of the National Institute of Environmental Health Sciences. The study required the well-controlled and characterized exposure of individually housed, unrestrained mice at 1900 MHz and rats at 900 MHz, frequencies chosen to give best uniformity exposure of organs and tissues. The wbSAR, the peak spatial SAR and the organ specific SAR as well as the uncertainty and variation due to the exposure environment, differences in the growth rates, and animal posture were assessed. Compared to the wbSAR, the average exposure of the high-water-content tissues (blood, heart, lung) were higher by ~4 dB, while the low-loss tissues (bone and fat) were less by ~9 dB. The maximum uncertainty over the exposure period for the SAR was estimated to be <49% (k=2) for the rodents whereas the relative uncertainty between the group was <14% (k=1). The instantaneous variation (averaged over 1 min) was <13% (k=1), which is small compared to other long term exposure research projects. These detailed dosimetric results empowers comparison with other studies and provides a reference for studies of long-term biological effects of exposure of rodents to RF energy.

Rectal bleeding after hypofractionated radiotherapy for prostate cancer: Correlation between clinical and dosimetric parameters and the incidence of grade 2 or worse rectal bleeding

International Nuclear Information System (INIS)

Akimoto, Tetsuo; Muramatsu, Hiroyuki; Takahashi, Mitsuhiro; Saito, Jun-ichi; Kitamoto, Yoshizumi; Harashima, Koichi; Miyazawa, Yasushi; Yamada, Masami; Ito, Kazuto; Kurokawa, Kouhei; Yamanaka, Hidetoshi; Nakano, Takashi; Mitsuhashi, Norio; Niibe, Hideo

2004-01-01

Purpose: To investigate the incidence and severity of rectal bleeding after high-dose hypofractionated radiotherapy (RT) for prostate cancer, and to explore the factors affecting the incidence of Grade 2 or worse rectal bleeding. Methods and materials: The data of 52 patients who had been treated by external beam RT for localized prostate cancer between 1999 and 2002 were analyzed. All the patients had received hypofractionated external beam RT to a total dose of 69 Gy in 3-Gy fractions, three fractions weekly. The clinical and dosimetric factors affecting the incidence of Grade 2 or worse late rectal bleeding were analyzed by univariate and multivariate analyses. The effect of the percentage of the whole rectal volume receiving 30%, 50%, 80%, and 90% of the prescribed radiation dose (V 30 , V 50 , V 80 , and V 90 , respectively) on the incidence of rectal bleeding was evaluated. Results: Of the 52 patients, 13 (25%) developed Grade 2 or worse rectal bleeding. One patient who needed laser coagulation and blood transfusion for the treatment of rectal bleeding was classified as having Grade 3 rectal bleeding. The median time to the development of Grade 2 or worse rectal bleeding was 11 months. The results of the univariate analysis revealed that the presence of a history of diabetes mellitus (p 30 ≥ 60%, V 50 ≥ 40% (p 80 ≥ 25%, and V 90 ≥ 15% (p < 0.001) were statistically significant risk factors for the occurrence of Grade 2 or worse rectal bleeding. The results of the multivariate analysis revealed that a history of diabetes mellitus was the most statistically significant risk factor for the occurrence of rectal bleeding after hypofractionated RT for prostate cancer (p < 0.05). Conclusion: A history of diabetes mellitus was the most statistically significant risk factor for the occurrence of Grade 2 or worse rectal bleeding after high-dose hypofractionated RT, although dosimetric factors were also closely associated with the risk of rectal bleeding

Comparison of the dosimetric parameters in linear accelerators with flattening filter-free (FFF) and flattening filter (FF)

International Nuclear Information System (INIS)

Souza, Anderson S.; Rostelato, Maria Elisa C.M.; Zeituni, Carlos A.; Moura, Eduardo S.; Rodrigues, Bruna T.; Souza, Daiane C.; Tiezzi, Rodrigo; Souza, Carla D.; Melo, Emerson R.; Camargo, Anderson R.; Batista, Talita Q.

2015-01-01

This paper discusses the main features associated with the dosimetric parameters between FFF and FF Linacs. A set of Varian TrueBeam Linac and Varian 23EX dosimetric measurements was acquired to perform the experimental measurements. The dose measurements were carried out in a water Blue phantom, with a waterproof ionization chambers: farmer ionization chamber (0.6 cm 3 ) and Exradin A1SL(0.053 cm 3 ) , for fields 5 x 5, 8 x 8, 10 x 10, 15 x 15, 30 x 30 cm 2 . The 6 MV FFF and FF was the energy used in this work. Percent Depth Dose (PDD) was the dosimetric parameters evaluated using a fixed Source Surface Distance of 100 cm. One depth were applied for the measurements, 10 cm (central axis) from the water surface. The 6 MV FFF showed less penetrating than the 6 MV FF. This is due to the removal flattening filter causes more lower energy photons on the central axis. The field sizes were equivalent for both FFF and FF. The main advantage in operate linear accelerators without flattening filter is due to the high doses rates delivered during the treatment. High doses rates could reduce the patient treatment time and may be beneficial for some treatment techniques such as IMRT and SRT. (author)

Dosimetric confirmation of a software for the design of radiotherapy

International Nuclear Information System (INIS)

Alfonso, R.; Huerta, U.; Torres, M.; Alonso, J.L.

1995-01-01

A software for radiotherapy treatment has been recently designed by specialists in medical physics form Hermanos Ameijeiras Clinical and Surgical Hospital. Several locations in the distributions of dose calculations. The results of dosimetric measurements with TLD-700 powder in a human-like manikin were taken as reference. The different options available for the entry of patients shape data are explained. A comparison of the results of measurements with calculations, is presented. Causes of discrepancies are analyzed and recommendations regarding the usefulness of the different for the collection of data from patients are made

Dosimetric Consistency of Co-60 Teletherapy Unit- a ten years Study.

Science.gov (United States)

Baba, Misba H; Mohib-Ul-Haq, M; Khan, Aijaz A

2013-01-01

The goal of the Radiation standards and Dosimetry is to ensure that the output of the Teletherapy Unit is within ±2% of the stated one and the output of the treatment dose calculation methods are within ±5%. In the present paper, we studied the dosimetry of Cobalt-60 (Co-60) Teletherapy unit at Sher-I-Kashmir Institute of Medical Sciences (SKIMS) for last 10 years. Radioactivity is the phenomenon of disintegration of unstable nuclides called radionuclides. Among these radionuclides, Cobalt-60, incorporated in Telecobalt Unit, is commonly used in therapeutic treatment of cancer. Cobalt-60 being unstable decays continuously into Ni-60 with half life of 5.27 years thereby resulting in the decrease in its activity, hence dose rate (output). It is, therefore, mandatory to measure the dose rate of the Cobalt-60 source regularly so that the patient receives the same dose every time as prescribed by the radiation oncologist. The under dosage may lead to unsatisfactory treatment of cancer and over dosage may cause radiation hazards. Our study emphasizes the consistency between actual output and output obtained using decay method. The methodology involved in the present study is the calculations of actual dose rate of Co-60 Teletherapy Unit by two techniques i.e. Source to Surface Distance (SSD) and Source to Axis Distance (SAD), used for the External Beam Radiotherapy, of various cancers, using the standard methods. Thereby, a year wise comparison has been made between average actual dosimetric output (dose rate) and the average expected output values (obtained by using decay method for Co-60.). The present study shows that there is a consistency in the average output (dose rate) obtained by the actual dosimetry values and the expected output values obtained using decay method. The values obtained by actual dosimetry are within ±2% of the expected values. The results thus obtained in a year wise comparison of average output by actual dosimetry done regularly as a part of

Dosimetric essay in dental radiology

International Nuclear Information System (INIS)

Lopez Salaberry, M.

1998-01-01

A neck study was observated in the tiroids glands,laryngeal zone, sensitive organs for the ionizing radiation for increase dental xray exams. Was selected 29th patients with radiography prescription complete (in the Odontology Faculty Clinics Uruguaian). It took radiographies with and without tiroids necklace and apron lead using dosemeters. Dosimetric studies had demonstrated good dose between patients. For measuring the radiation dose have been used TLD thermoluminescence dosimetric and Harshaw 6600 for read it. The thyroids necklace use and odontology postgrading for training course for dentistry was the two recommendations advised

The dosimetric control in radiotherapy

International Nuclear Information System (INIS)

Veres, A.

2009-01-01

The author first presents the thermoluminescent dosimetry method developed by the Equal-Estro Laboratory to control radiotherapy systems, according to which dosimeters are mailed by the radiotherapy centres to the laboratory, and then analyzed with respect to the level of dose bias. In a second part, he discusses the different techniques used for the dosimetric control of new radiotherapy methods (intensity-modulated radiation therapy, tomo-therapy) for which film dosimetry is applied. He also evokes the development of new phantoms and the development of a method for the dosimetric control of proton beams

SU-D-19A-07: Dosimetric Comparison of HDR Plesiotherapy and Electron Beam Therapy for Superficial Lesions

Energy Technology Data Exchange (ETDEWEB)

Mitchell, A; Jacob, D; Andreou, K; Raben, A; Chen, H; Koprowski, C; Mourtada, F [Christiana Care Hospital, Newark, DE (United States)

2014-06-01

Purpose: Large superficial (skin, soft tissue sarcoma) lesions located on curved areas are hard to treat with electrons. The Freiburg Flap (Nucletron, Netherlands) is a flexible mesh style surface which can be easily shaped to fit curved surfaces for reproducible HDR fraction delivery. To understand the fundamental dosimetric differences, a dosimetric comparison was made between HDR plesiotherapy (Freiburg applicator for lesions over 4cm) and external electron beam radiotherapy over cases with varying target curvature (both stylized and clinical cases). Methods: Four stylized cases with variable complexity were created using artificial DICOM axial CT slices and RT structures (a square and three curved structures on a 4.5cm radius cylinder). They were planned using Oncentra v4.3 and exported to Pinnacle v9.6 for electrons planning. The HDR source dwell positions were optimized for the best coverage of the targets using graphical optimization. Electron treatment plans were created in Pinnacle using the same CT and RT structures of three HDR cases with surface lesions previously treated with the Freiburg flap. The En face electron plans used 6-12 MeV electrons and 0.5–1 cm bolus was added to increase surface dose. The electron plans were prescribed to an isodose line to conform to the target. Results: For all lesions, the average target dose coverage was similar (D90ave of 100% for HDR vs 101% for electrons). For lesions with high curvature, the HDR coverage was better (D90 102% vs D90 97% for electron). For all cases, adjacent structures high dose region was lower for HDR than electrons (D1cc 100% for HDR vs D1cc 111% for electrons). Conclusion: HDR plesiotherapy offers excellent target conformity for superficial targets similar to electrons. However, for lesions with complex curved surfaces, HDR has the advantage to achieve better dose distributions using graphical optimization to spare adjacent normal tissue while maximizing target coverage.

Brachial Plexopathy in Apical Non-Small Cell Lung Cancer Treated With Definitive Radiation: Dosimetric Analysis and Clinical Implications

International Nuclear Information System (INIS)

Eblan, Michael J.; Corradetti, Michael N.; Lukens, J. Nicholas; Xanthopoulos, Eric; Mitra, Nandita; Christodouleas, John P.; Grover, Surbhi; Fernandes, Annemarie T.; Langer, Corey J.; Evans, Tracey L.; Stevenson, James; Rengan, Ramesh; Apisarnthanarax, Smith

2013-01-01

Purpose: Data are limited on the clinical significance of brachial plexopathy in patients with apical non-small cell lung cancers (NSCLC) treated with definitive radiation therapy. We report the rates of radiation-induced brachial plexopathy (RIBP) and tumor-related brachial plexopathy (TRBP) and associated dosimetric parameters in apical NSCLC patients. Methods and Materials: Charts of NSCLC patients with primary upper lobe or superiorly located nodal disease who received ≥50 Gy of definitive conventionally fractionated radiation or chemoradiation were retrospectively reviewed for evidence of brachial plexopathy and categorized as RIBP, TRBP, or trauma-related. Dosimetric data were gathered on ipsilateral brachial plexuses (IBP) contoured according to Radiation Therapy Oncology Group atlas guidelines. Results: Eighty patients were identified with a median follow-up and survival time of 17.2 and 17.7 months, respectively. The median prescribed dose was 66.6 Gy (range, 50.4-84.0), and 71% of patients received concurrent chemotherapy. RIBP occurred in 5 patients with an estimated 3-year rate of 12% when accounting for competing risk of death. Seven patients developed TRBP (estimated 3-year rate of 13%), comprising 24% of patients who developed locoregional failures. Grade 3 brachial plexopathy was more common in patients who experienced TRBP than RIBP (57% vs 20%). No patient who received ≤78 Gy to the IBP developed RIBP. On multivariable competing risk analysis, IBP V76 receiving ≥1 cc, and primary tumor failure had the highest hazard ratios for developing RIBP and TRBP, respectively. Conclusions: RIBP is a relatively uncommon complication in patients with apical NSCLC tumors receiving definitive doses of radiation, while patients who develop primary tumor failures are at high risk for developing morbid TRBP. These findings suggest that the importance of primary tumor control with adequate doses of radiation outweigh the risk of RIBP in this population of

Late rectal toxicity: dose-volume effects of conformal radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Huang, Eugene H.; Pollack, Alan; Levy, Larry; Starkschall, George; Lei Dong; Rosen, Isaac; Kuban, Deborah A.

2002-01-01

Purpose: To identify dosimetric, anatomic, and clinical factors that correlate with late rectal toxicity after three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer. Methods and Materials: We retrospectively analyzed the dose-volume histograms and clinical records of 163 Stage T1b-T3c prostate cancer patients treated between 1992 and 1999 with 3D-CRT, to a total isocenter dose of 74-78 Gy at The University of Texas M. D. Anderson Cancer Center. The median follow-up was 62 months (range 24-102). All late rectal complications were scored using modified Radiation Therapy Oncology Group and Late Effects Normal Tissue Task Force criteria. The 6-year toxicity rate was assessed using Kaplan-Meier analysis and the log-rank test. A univariate proportional hazards regression model was used to test the correlation between Grade 2 or higher toxicity and the dosimetric, anatomic, and clinical factors. In a multivariate regression model, clinical factors were added to the dosimetric and anatomic variables to determine whether they significantly altered the risk of developing late toxicity. Results: At 6 years, the rate of developing Grade 2 or higher late rectal toxicity was 25%. A significant volume effect was observed at rectal doses of 60, 70, 75.6, and 78 Gy, and the risk of developing rectal complications increased exponentially as greater volumes were irradiated. Although the percentage of rectal volume treated correlated significantly with the incidence of rectal complications at all dose levels (p 3 of the rectum. Of the clinical variables tested, only a history of hemorrhoids correlated with rectal toxicity (p=0.003). Multivariate analysis showed that the addition of hemorrhoids increased the risk of toxicity for each dosimetric variable found to be significant on univariate analysis (p<0.05 for all comparisons). Conclusion: Dose-volume histogram analyses clearly indicated a volume effect on the probability of developing late rectal complications

SU-E-T-310: Dosimetric Comparison of Tandem and Ovoid (TO) Vs. Tandem and Ring (TR) Applicators in High-Dose Rate (HDR) Brachytherapy (BT) for the Treatment of Locally-Advanced Cervical-Cancer

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Kuo, L; Viswanathan, A; Damato, A [Brigham and Women’s Hospital, Boston, MA (United States)

2015-06-15

Purpose: To investigate the dosimetric differences associated with the use of TO or TR applicators for cervical-cancer HDR BT. Methods: The records of all cervical-cancer patients treated with image-guided HDR BT in 2013 were reviewed. Image-based planning based on isodose line and DVH metrics inspections was performed following the GEC-ESTRO recommendations. CTV volume, CTV D90, and rectum, bladder and sigmoid D2cc were collected as % of the prescription dose (80Gy EQD2). Patients receiving both TO and TR were identified and plans were compared (paired analysis). A Student T-test was used to evaluate statistical significance (p ≤ 0.05). Results: Twenty-eight patients were identified (20 TR only, 4 TO only, 4 TO and TR), associated with 116 plans (109 TR, 7 TO). Overall metrics: CTV volume, 26.5±10.4 cm3 (TR) and 39.1±14.0 cm3 (TO, p < 0.01); CTV D90, 126±28% (TR) and 110±15% (TO, p = 0.15); rectum D2cc, 56±11% (TR) and 58±19% (TO, p = 0.91); bladder D2cc, 74±20% (TR) and 88±19% (TO, p = 0.09); sigmoid D2cc, 52±17% (TR) and 49±20% (TO, p = 0.63). The paired analysis results were: CTV volume, 37.3±11.9 cm3 (TR) and 51.0±23.1 cm3 (TO, p = 0.23); CTV D90, 111±12% (TR) and 101±17% (TO, p = 0.50); rectum D2cc, 56±12% (TR) and 53±16% (TO, p = 0.71); bladder D2cc, 73±14% (TR) and 90±20% (TO, p = 0.22); sigmoid D2cc, 59±10% (TR) and 59±22% (TO, p = 0.98). Conclusion: TR and TO were both used with good dosimetric results. TO were used for patients with larger CTV volumes than TR, although paired analysis suggest that tissue distortion and contouring bias may partially explain this Result. CTV D90 on average > 80 Gy EQD2 were achieved in both groups despite the different CTV volume. Higher bladder D2cc for TO than TR was observed.

SU-E-T-327: Dosimetric Impact of Beam Energy for Intrabeam Breast IORT with Different Residual Cancer Cell Distributions After Surgery

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Schwid, M; Zhang, H [Department of Radiation Oncology, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL (United States)

2015-06-15

Purpose: The purpose of this study was to evaluate the dosimetric impact of beam energy to the IORT treatment of residual cancer cells with different cancer cell distributions after breast-conserving surgery. Methods: The three dimensional (3D) radiation doses of IORT using a 4-cm spherical applicator at the energy of 40 keV and 50 keV were separately calculated at different depths of the postsurgical tumor bed. The modified linear quadratic model (MLQ) was used to estimate the radiobiological response of the tumor cells assuming different radio-sensitivities and density distributions. The impact of radiation was evaluated for two types of breast cancer cell lines (α /β=10, and α /β =3.8) at 20 Gy dose prescribed at the applicator surface. Cancer cell distributions in the postsurgical tissue field were assumed to be a Gaussian with the standard deviations of 0.5, 1 and 2 mm respectively, namely the cancer cell infiltrations of 1.5, 3, and 6 mm respectively. The surface cancer cell percentage was assumed to be 0.01%, 0.1%, 1% and 10% separately. The equivalent uniform doses (EUD) for all the scenarios were calculated. Results: The EUDs were found to be dependent on the distributions of cancer cells, but independent of the cancer cell radio-sensitivities and the density at the surface. EUDs of 50 keV are 1% larger than that of 40 keV. For a prescription dose of 20 Gy, EUDs of 50 keV beam are 17.52, 16.21 and 13.14 Gy respectively for 0.5, 1.0 and 2.0 mm of the standard deviation of cancer cell Gaussian distributions. Conclusion: The impact by selected energies of IORT beams is very minimal. When energy is changed from 50 keV to 40 keV, the EUDs are almost the same for the same cancer cell distribution. 40 keV can be safely used as an alternative of 50 keV beam in IORT.

SU-E-T-327: Dosimetric Impact of Beam Energy for Intrabeam Breast IORT with Different Residual Cancer Cell Distributions After Surgery

International Nuclear Information System (INIS)

Schwid, M; Zhang, H

2015-01-01

Purpose: The purpose of this study was to evaluate the dosimetric impact of beam energy to the IORT treatment of residual cancer cells with different cancer cell distributions after breast-conserving surgery. Methods: The three dimensional (3D) radiation doses of IORT using a 4-cm spherical applicator at the energy of 40 keV and 50 keV were separately calculated at different depths of the postsurgical tumor bed. The modified linear quadratic model (MLQ) was used to estimate the radiobiological response of the tumor cells assuming different radio-sensitivities and density distributions. The impact of radiation was evaluated for two types of breast cancer cell lines (α /β=10, and α /β =3.8) at 20 Gy dose prescribed at the applicator surface. Cancer cell distributions in the postsurgical tissue field were assumed to be a Gaussian with the standard deviations of 0.5, 1 and 2 mm respectively, namely the cancer cell infiltrations of 1.5, 3, and 6 mm respectively. The surface cancer cell percentage was assumed to be 0.01%, 0.1%, 1% and 10% separately. The equivalent uniform doses (EUD) for all the scenarios were calculated. Results: The EUDs were found to be dependent on the distributions of cancer cells, but independent of the cancer cell radio-sensitivities and the density at the surface. EUDs of 50 keV are 1% larger than that of 40 keV. For a prescription dose of 20 Gy, EUDs of 50 keV beam are 17.52, 16.21 and 13.14 Gy respectively for 0.5, 1.0 and 2.0 mm of the standard deviation of cancer cell Gaussian distributions. Conclusion: The impact by selected energies of IORT beams is very minimal. When energy is changed from 50 keV to 40 keV, the EUDs are almost the same for the same cancer cell distribution. 40 keV can be safely used as an alternative of 50 keV beam in IORT

Balloon-based adjuvant radiotherapy in breast cancer: comparison between 99mTc and HDR 192Ir

Directory of Open Access Journals (Sweden)

Tarcísio Passos Ribeiro de Campos

2016-04-01

Full Text Available Abstract Objective: To perform a comparative dosimetric analysis, based on computer simulations, of temporary balloon implants with 99mTc and balloon brachytherapy with high-dose-rate (HDR 192Ir, as boosts to radiotherapy. We hypothesized that the two techniques would produce equivalent doses under pre-established conditions of activity and exposure time. Materials and Methods: Simulations of implants with 99mTc-filled and HDR 192Ir-filled balloons were performed with the Siscodes/MCNP5, modeling in voxels a magnetic resonance imaging set related to a young female. Spatial dose rate distributions were determined. In the dosimetric analysis of the protocols, the exposure time and the level of activity required were specified. Results: The 99mTc balloon presented a weighted dose rate in the tumor bed of 0.428 cGy.h-1.mCi-1 and 0.190 cGyh-1.mCi-1 at the balloon surface and at 8-10 mm from the surface, respectively, compared with 0.499 and 0.150 cGyh-1.mCi-1, respectively, for the HDR 192Ir balloon. An exposure time of 24 hours was required for the 99mTc balloon to produce a boost of 10.14 Gy with 1.0 Ci, whereas only 24 minutes with 10.0 Ci segments were required for the HDR 192Ir balloon to produce a boost of 5.14 Gy at the same reference point, or 10.28 Gy in two 24-minutes fractions. Conclusion: Temporary 99mTc balloon implantation is an attractive option for adjuvant radiotherapy in breast cancer, because of its availability, economic viability, and similar dosimetry in comparison with the use of HDR 192Ir balloon implantation, which is the current standard in clinical practice.

Design, manufacture, and evaluation of an anthropomorphic pelvic phantom purpose-built for radiotherapy dosimetric intercomparison

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Harrison, K. M.; Ebert, M. A.; Kron, T.; Howlett, S. J.; Cornes, D.; Hamilton, C. S.; Denham, J. W. [Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales 2298, Australia and School of Physics, University of Newcastle, New South Wales 2308 (Australia); Department of Radiation Oncology, Sir Charles Gairdner Hospital, Western Australia, Australia and School of Physics, University of Western Australia, Western Australia 6009 (Australia); Department of Physical Sciences, Peter MacCallum Cancer Centre, Victoria 8006 (Australia); Australiasian College of Physical Scientists and Engineers in Medicine, Sydney, New South Wales 2020 (Australia); Trans-Tasman Radiation Oncology Group, Calvary Mater Newcastle, New South Wales 2298 (Australia); Heidelberg Repatriation Hospital, Victoria 3081 (Australia); Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales 2298, Australia and School of Medicine and Population Health, University of Newcastle, New South Wales 2308 (Australia)

2011-10-15

Purpose: An anthropomorphic pelvic phantom was designed and constructed to meet specific criteria for multicenter radiotherapy dosimetric intercomparison. Methods: Three dimensional external and organ outlines were generated from a computed tomography image set of a male pelvis, forming the basis of design for an anatomically realistic phantom. Clinically relevant points of interest were selected throughout the dataset where point-dose values could be measured with thermoluminescence dosimeters and a small-volume ionization chamber. Following testing, three materials were selected and the phantom was manufactured using modern prototyping techniques into five separate coronal slices. Time lines and resource requirements for the phantom design and manufacture were recorded. The ability of the phantom to mimic the entire treatment chain was tested. Results: The phantom CT images indicated that organ densities and geometries were comparable to those of the original patient. The phantom proved simple to load for dosimetry and rapid to assemble. Due to heat release during manufacture, small air gaps and density heterogeneities were present throughout the phantom. The overall cost for production of the prototype phantom was comparable to other commercial anthropomorphic phantoms. The phantom was shown to be suitable for use as a ''patient'' to mimic the entire treatment chain for typical external beam radiotherapy for prostate and rectal cancer. Conclusions: The phantom constructed for the present study incorporates all characteristics necessary for accurate Level III intercomparison studies. Following use in an extensive Level III dosimetric comparison over a large time scale and geographic area, the phantom retained mechanical stability and did not show signs of radiation-induced degradation.

Dosimetric quality assurance of highly conformal external beam treatments: from 2D phantom comparisons to 4D patient dose reconstruction

International Nuclear Information System (INIS)

Feygelman, V; Nelms, B

2013-01-01

As IMRT technology continues to evolve, so do the dosimetric QA methods. A historical review of those is presented, starting with longstanding techniques such as film and ion chamber in a phantom and progressing towards 3D and 4D dose reconstruction in the patient. Regarding patient-specific QA, we envision that the currently prevalent limited comparison of dose distributions in the phantom by γ-analysis will be eventually replaced by clinically meaningful patient dose analyses with improved sensitivity and specificity. In a larger sense, we envision a future of QA built upon lessons from the rich history of ''quality'' as a science and philosophy. This future will aim to improve quality (and ultimately reduce cost) via advanced commissioning processes that succeed in detecting and rooting out systematic errors upstream of patient treatment, thus reducing our reliance on, and the resource burden associated with, per-beam/per-plan inspection.

Dosimetric quality assurance of highly conformal external beam treatments: from 2D phantom comparisons to 4D patient dose reconstruction

Science.gov (United States)

Feygelman, V.; Nelms, B.

2013-06-01

As IMRT technology continues to evolve, so do the dosimetric QA methods. A historical review of those is presented, starting with longstanding techniques such as film and ion chamber in a phantom and progressing towards 3D and 4D dose reconstruction in the patient. Regarding patient-specific QA, we envision that the currently prevalent limited comparison of dose distributions in the phantom by γ-analysis will be eventually replaced by clinically meaningful patient dose analyses with improved sensitivity and specificity. In a larger sense, we envision a future of QA built upon lessons from the rich history of "quality" as a science and philosophy. This future will aim to improve quality (and ultimately reduce cost) via advanced commissioning processes that succeed in detecting and rooting out systematic errors upstream of patient treatment, thus reducing our reliance on, and the resource burden associated with, per-beam/per-plan inspection.

Dosimetric impact of image-guided 3D conformal radiation therapy of prostate cancer

International Nuclear Information System (INIS)

Schaly, B; Song, W; Bauman, G S; Battista, J J; Van Dyk, J

2005-01-01

The goal of this work is to quantify the impact of image-guided conformal radiation therapy (CRT) on the dose distribution by correcting patient setup uncertainty and inter-fraction tumour motion. This was a retrospective analysis that used five randomly selected prostate cancer patients that underwent approximately 15 computed tomography (CT) scans during their radiation treatment course. The beam arrangement from the treatment plan was imported into each repeat CT study and the dose distribution was recalculated for the new beam setups. Various setup scenarios were then compared to assess the impact of image guidance on radiation treatment precision. These included (1) daily alignment to skin markers, thus representing a conventional beam setup without image guidance (2) alignment to bony anatomy for correction of daily patient setup error, thus representing on-line portal image guidance, and (3) alignment to the 'CTV of the day' for correction of inter-fraction tumour motion, thus representing on-line CT or ultrasound image guidance. Treatment scenarios (1) and (3) were repeated with a reduced CTV to PTV margin, where the former represents a treatment using small margins without daily image guidance. Daily realignment of the treatment beams to the prostate showed an average increase in minimum tumour dose of 1.5 Gy, in all cases where tumour 'geographic miss' without image guidance was apparent. However, normal tissue sparing did not improve unless the PTV margin was reduced. Daily realignment to the tumour combined with reducing the margin size by a factor of 2 resulted in an average escalation in tumour dose of 9.0 Gy for all five static plans. However, the prescription dose could be escalated by 13.8 Gy when accounting for changes in anatomy by accumulating daily doses using nonlinear image registration techniques. These results provide quantitative information on the effectiveness of image-guided radiation treatment of prostate cancer and demonstrate that

Comparison of dosimetric characteristics of Siemens virtual and physical wedges for ONCOR linear accelerator

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Attalla Ehab

2010-01-01

Full Text Available Dosimetric properties of virtual wedge (VW and physical wedge (PW in 6- and 10-MV photon beams from a Siemens ONCOR linear accelerator, including wedge factors, depth doses, dose profiles, peripheral doses, are compared. While there is a great difference in absolute values of wedge factors, VW factors (VWFs and PW factors (PWFs have a similar trend as a function of field size. PWFs have stronger depth dependence than VWF due to beam hardening in PW fields. VW dose profiles in the wedge direction, in general, match very well with those of PW, except in the toe area of large wedge angles with large field sizes. Dose profiles in the nonwedge direction show a significant reduction in PW fields due to off-axis beam softening and oblique filtration. PW fields have significantly higher peripheral doses than open and VW fields. VW fields have similar surface doses as the open fields, while PW fields have lower surface doses. Surface doses for both VW and PW increase with field size and slightly with wedge angle. For VW fields with wedge angles 45° and less, the initial gap up to 3 cm is dosimetrically acceptable when compared to dose profiles of PW. VW fields in general use less monitor units than PW fields.

Dosimetric Comparison of Manual and Beam Angle Optimization of Gantry Angles in IMRT

International Nuclear Information System (INIS)

Srivastava, Shiv P.; Das, Indra J.; Kumar, Arvind; Johnstone, Peter A.S.

2011-01-01

Dosimetric comparison of manual beam angle selection (MBS) and beam angle optimization (BAO) for IMRT plans is investigated retrospectively for 15 head and neck and prostate patients. The head and neck and prostate had planning target volumes (PTVs) ranging between 96.0 and 319.9 cm 3 and 153.6 and 321.3 cm 3 , whereas OAR ranged between 8.3 and 47.8 cm 3 and 68.3 and 469.2 cm 3 , respectively. In MBS, a standard coplanar 7-9 fields equally spaced gantry angles were used. In BAO, the selection of gantry angle was optimized by the algorithm for the same number of beams. The optimization and dose-volume constraints were kept the same for both techniques. Treatment planning was performed on the Eclipse treatment planning system. Our results showed that the dose-volume histogram for PTV are nearly identical in both techniques but BAO provided superior sparing of the organs at risk compared with the MBS. Also, MBS produced statistically significant higher monitor units (MU) and segments than the BAO; 13.1 ± 6.6% (p = 0.012) and 10.4 ± 13.6% (p = 0.140), and 14.6 ± 5.6% (p = 1.003E-5) and 12.6 ± 7.4% (p = 0.76E-3) for head and neck and prostate cases, respectively. The reduction in MU translates into the reduction in total body and integral dose. It is concluded that BAO provides advantage over MBS for most intenisty-modulated radiation therapy cases.

Transformation of Physical DVHs to Radiobiologically Equivalent Ones in Hypofractionated Radiotherapy Analyzing Dosimetric and Clinical Parameters: A Practical Approach for Routine Clinical Practice in Radiation Oncology

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Zoi Thrapsanioti

2013-01-01

Full Text Available Purpose. The purpose of this study was to transform DVHs from physical to radiobiological ones as well as to evaluate their reliability by correlations of dosimetric and clinical parameters for 50 patients with prostate cancer and 50 patients with breast cancer, who were submitted to Hypofractionated Radiotherapy. Methods and Materials. To achieve this transformation, we used both the linear-quadratic model (LQ model and the Niemierko model. The outcome of radiobiological DVHs was correlated with acute toxicity score according to EORTC/RTOG criteria. Results. Concerning the prostate radiotherapy, there was a significant correlation between RTOG acute rectal toxicity and ( and ( dosimetric parameters, calculated for  Gy. Moreover, concerning the breast radiotherapy there was a significant correlation between RTOG skin toxicity and dosimetric parameter, calculated for both  Gy ( and  Gy (. The new tool seems reliable and user-friendly. Conclusions. Our proposed model seems user-friendly. Its reliability in terms of agreement with the presented acute radiation induced toxicity was satisfactory. However, more patients are needed to extract safe conclusions.

Applications of sensitivity function to dosimetric data adjustments

International Nuclear Information System (INIS)

Nakazawa, Masaharu

1984-01-01

Sensitivity functions are applied to the dosimetric field in the spectrum unfolding technique, also called as the data adjustment technique which are statistical estimation procedures of the neutron spectrum or relating dosimetric quantities basing on the reaction-rate data measurements. Using the practical formulae and numerical examples of the sensitivity functions in the dosimetric data adjustments, two comments are made that (1) present sensitivity values are highly depending on the initial spectrum inputs and (2) more attention should be paid to the dependency of the sensitivity on the very uncertain covariance data inputs of the initial neutron spectrum. (author)

Social comparisons and quality of life following a prostate cancer diagnosis.

Science.gov (United States)

Umstead, Kendall L; Kalia, Sarah S; Madeo, Anne C; Erby, Lori H; Blank, Thomas O; Visvanathan, Kala; Roter, Debra L

2018-02-09

The objective was to explore the relationships among cognitive appraisals of prostate cancer (challenge, threat, and harm/loss), social comparisons, and quality of life in men previously diagnosed. Design, Sample, & Methods: Men who had participated in prostate cancer support groups completed a cross-sectional questionnaire (N = 189). Multivariable linear regression was used to evaluate social comparisons as mediators of quality of life while controlling for uncertainty and optimism. Positive and negative social comparisons were parallel mediators of the relationships between challenge or threat appraisals and quality of life, while only negative social comparisons mediated the relationship between harm/loss appraisals and quality of life. These findings demonstrate the importance of social comparisons in accounting for the effect of cognitive appraisals of prostate cancer on quality of life among men in support groups. Implications for Psychosocial Providers: Interventions to improve quality of life could address reduction of maladaptive comparisons, a strategy that could be tailored based on the patient's appraisal of prostate cancer.

Chemo-IMRT of Oropharyngeal Cancer Aiming to Reduce Dysphagia: Swallowing Organs Late Complication Probabilities and Dosimetric Correlates

International Nuclear Information System (INIS)

Eisbruch, Avraham; Kim, Hyungjin M.; Feng, Felix Y.; Lyden, Teresa H.; Haxer, Marc J.; Feng, Mary; Worden, Frank P.; Bradford, Carol R.; Prince, Mark E.; Moyer, Jeffrey S.; Wolf, Gregory T.; Chepeha, Douglas B.; Ten Haken, Randall K.

2011-01-01

Purpose: Assess dosimetric correlates of long-term dysphagia after chemo-intensity-modulated radiotherapy (IMRT) of oropharyngeal cancer (OPC) sparing parts of the swallowing organs. Patients and Methods: Prospective longitudinal study: weekly chemotherapy concurrent with IMRT for Stages III/IV OPC, aiming to reduce dysphagia by sparing noninvolved parts of swallowing-related organs: pharyngeal constrictors (PC), glottic and supraglottic larynx (GSL), and esophagus, as well as oral cavity and major salivary glands. Dysphagia outcomes included patient-reported Swallowing and Eating Domain scores, Observer-based (CTCAEv.2) dysphagia, and videofluoroscopy (VF), before and periodically after therapy through 2 years. Relationships between dosimetric factors and worsening (from baseline) of dysphagia through 2 years were assessed by linear mixed-effects model. Results: Seventy-three patients participated. Observer-based dysphagia was not modeled because at >6 months there were only four Grade ≥2 cases (one of whom was feeding-tube dependent). PC, GSL, and esophagus mean doses, as well as their partial volume doses (V D s), were each significantly correlated with all dysphagia outcomes. However, the V D s for each organ intercorrelated and also highly correlated with the mean doses, leaving only mean doses significant. Mean doses to each of the parts of the PCs (superior, middle, and inferior) were also significantly correlated with all dysphagia measures, with superior PCs demonstrating highest correlations. For VF-based strictures, most significant predictor was esophageal mean doses (48±17 Gy in patients with, vs 27±12 in patients without strictures, p = 0.004). Normal tissue complication probabilities (NTCPs) increased moderately with mean doses without any threshold. For increased VF-based aspirations or worsened VF summary scores, toxic doses (TDs) 50 and TD 25 were 63 Gy and 56 Gy for PC, and 56 Gy and 39 Gy for GSL, respectively. For both PC and GSL, patient

Comparison of dosimetric parameters and toxicity in esophageal cancer patients undergoing 3D conformal radiotherapy or VMAT

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Muench, Stefan; Aichmeier, Sylvia; Duma, Marciana-Nona; Oechsner, Markus; Habermehl, Daniel [TU Muenchen, Department of Radiation Oncology, Klinikum rechts der Isar, Muenchen (Germany); Hapfelmeier, Alexander [TU Muenchen, Institute of Medical Statistics and Epidemiology (IMSE), Klinikum rechts der Isar, Muenchen (Germany); Feith, Marcus [TU Muenchen, Department of Visceral Surgery, Klinikum rechts der Isar, Muenchen (Germany); Combs, Stephanie E. [TU Muenchen, Department of Radiation Oncology, Klinikum rechts der Isar, Muenchen (Germany); Helmholtz Zentrum Muenchen, Institute of Innovative Radiotherapy (iRT), Oberschleissheim (Germany)

2016-10-15

Volumetric-modulated arc therapy (VMAT) achieves high conformity to the planned target volume (PTV) and good sparing of organs at risk (OAR). This study compares dosimetric parameters and toxicity in esophageal cancer (EC) patients treated with VMAT and 3D conformal radiotherapy (3D-CRT). Between 2007 and 2014, 17 SC patients received neoadjuvant chemoradiation (CRT) with VMAT. Dose-volume histograms and toxicity were compared between these patients and 20 treated with 3D-CRT. All patients were irradiated with a total dose of 45 Gy. All VMAT patients received simultaneous chemotherapy with cisplatin and 5-fluorouracil (5-FU) in treatment weeks 1 and 5. Of 20 patients treated with 3D-CRT, 13 (65 %) also received CRT with cisplatin and 5-FU, whereas 6 patients (30 %) received CRT with weekly oxaliplatin and cetuximab, and a continuous infusion of 5-FU (OE-7). There were no differences in baseline characteristics between the treatment groups. For the lungs, VMAT was associated with a higher V{sub 5} (median 90.1 % vs. 79.7 %; p = 0.013) and V{sub 10} (68.2 % vs. 56.6 %; p = 0.014), but with a lower V{sub 30} (median 6.6 % vs. 11.0 %; p = 0.030). Regarding heart parameters, VMAT was associated with a higher V{sub 5} (median 100.0 % vs. 91.0 %; p = 0.043), V{sub 10} (92.0 % vs. 79.2 %; p = 0.047), and D{sub max} (47.5 Gy vs. 46.3 Gy; p = 0.003), but with a lower median dose (18.7 Gy vs. 30.0 Gy; p = 0.026) and V{sub 30} (17.7 % vs. 50.4 %; p = 0.015). Complete resection was achieved in 16 VMAT and 19 3D-CRT patients. Due to systemic progression, 2 patients did not undergo surgery. The most frequent postoperative complication was anastomosis insufficiency, occurring in 1 VMAT (6.7 %) and 5 3D-CRT patients (27.8 %; p = 0.180). Postoperative pneumonia was seen in 2 patients of each group (p = 1.000). There was no significant difference in 3-year overall (65 % VMAT vs. 45 % 3D-CRT; p = 0.493) or 3-year progression-free survival (53 % VMAT vs. 35 % 3D-CRT; p = 0

SU-E-J-170: Dosimetric Consequences of Uncorrected Rotational Setup Errors During Stereotactic Body Radiation Therapy (SBRT) Treatment of Pancreatic Cancers

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Di Maso, L [Chicago, IL (United States); Forbang, R Teboh; Zhang, Y; Herman, J; Lee, J [John Hopkins University, Baltimore, MD (United States)

2015-06-15

Purpose: To explore the dosimetric consequences of uncorrected rotational setup errors during SBRT for pancreatic cancer patients. Methods: This was a retrospective study utilizing data from ten (n=10) previously treated SBRT pancreas patients. For each original planning CT, we applied rotational transformations to derive additional CT images representative of possible rotational setup errors. This resulted in 6 different sets of rotational combinations, creating a total of 60 CT planning images. The patients’ clinical dosimetric plans were then applied to their corresponding rotated CT images. The 6 rotation sets encompassed a 3, 2 and 1-degree rotation in each rotational direction and a 3-degree in just the pitch, a 3-degree in just the yaw and a 3-degree in just the roll. After the dosimetric plan was applied to the rotated CT images, the resulting plan was then evaluated and compared with the clinical plan for tumor coverage and normal tissue sparing. Results: PTV coverage, defined here by V33 throughout all of the patients’ clinical plans, ranged from 92–98%. After an n degree rotation in each rotational direction that range decreased to 68–87%, 85–92%, and 88– 94% for n=3, 2 and 1 respectively. Normal tissue sparing defined here by the proximal stomach V15 throughout all of the patients’ clinical plans ranged from 0–8.9 cc. After an n degree rotation in each rotational direction that range increased to 0–17 cc, 0–12 cc, and 0–10 cc for n=3, 2, and 1 respectively. Conclusion: For pancreatic SBRT, small rotational setup errors in the pitch, yaw and roll direction on average caused under dosage to PTV and over dosage to proximal normal tissue. The 1-degree rotation was on average the least detrimental to the normal tissue and the coverage of the PTV. The 3-degree yaw created on average the lowest increase in volume coverage to normal tissue. This research was sponsored by the AAPM Education Council through the AAPM Education and Research

Evolution of dosimetric phantoms

International Nuclear Information System (INIS)

Reddy, A.R.

2010-01-01

In this oration evolution of the dosimetric phantoms for radiation protection and for medical use is briefly reviewed. Some details of the development of Indian Reference Phantom for internal dose estimation are also presented

SU-G-TeP1-05: Development and Clinical Introduction of Automated Radiotherapy Treatment Planning for Prostate Cancer

International Nuclear Information System (INIS)

Winkel, D; Bol, GH; Asselen, B van; Hes, J; Scholten, V; Kerkmeijer, LGW; Raaymakers, BW

2016-01-01

Purpose: To develop an automated radiotherapy treatment planning and optimization workflow for prostate cancer in order to generate clinical treatment plans. Methods: A fully automated radiotherapy treatment planning and optimization workflow was developed based on the treatment planning system Monaco (Elekta AB, Stockholm, Sweden). To evaluate our method, a retrospective planning study (n=100) was performed on patients treated for prostate cancer with 5 field intensity modulated radiotherapy, receiving a dose of 35×2Gy to the prostate and vesicles and a simultaneous integrated boost of 35×0.2Gy to the prostate only. A comparison was made between the dosimetric values of the automatically and manually generated plans. Operator time to generate a plan and plan efficiency was measured. Results: A comparison of the dosimetric values show that automatically generated plans yield more beneficial dosimetric values. In automatic plans reductions of 43% in the V72Gy of the rectum and 13% in the V72Gy of the bladder are observed when compared to the manually generated plans. Smaller variance in dosimetric values is seen, i.e. the intra- and interplanner variability is decreased. For 97% of the automatically generated plans and 86% of the clinical plans all criteria for target coverage and organs at risk constraints are met. The amount of plan segments and monitor units is reduced by 13% and 9% respectively. Automated planning requires less than one minute of operator time compared to over an hour for manual planning. Conclusion: The automatically generated plans are highly suitable for clinical use. The plans have less variance and a large gain in time efficiency has been achieved. Currently, a pilot study is performed, comparing the preference of the clinician and clinical physicist for the automatic versus manual plan. Future work will include expanding our automated treatment planning method to other tumor sites and develop other automated radiotherapy workflows.

Dosimetric impacts of endorectal balloon in CyberKnife stereotactic body radiation therapy (SBRT) for early-stage prostate cancer.

Science.gov (United States)

Xiang, Hong F; Lu, Hsiao-Ming; Efstathiou, Jason A; Zietman, Anthony L; De Armas, Ricardo; Harris, Kathryn; Bloch, B Nicolas; Qureshi, Muhammad Mustafa; Keohan, Sean; Hirsch, Ariel E

2017-05-01

In SBRT for prostate cancer, higher fractional dose to the rectum is a major toxicity concern due to using smaller PTV margin and hypofractionation. We investigate the dosimetric impact on rectum using endorectal balloon (ERB) in prostate SBRT. Twenty prostate cancer patients were included in a retrospective study, ten with ERB and 10 without ERB. Optimized SBRT plans were generated on CyberKnife MultiPlan for 5 × 7.25 Gy to PTV under RTOG-0938 protocol for early-stage prostate cancer. For the rectum and the anterior half rectum, mean dose and percentage of volumes receiving 50%, 80%, 90%, and 100% prescription dose were compared. Using ERB, mean dose to the rectum was 62 cGy (P = 0.001) lower per fraction, and 50 cGy (P = 0.024) lower per fraction for the anterior half rectum. The average V 50% , V 80% , V 90% , and V 100% were lower by 9.9% (P = 0.001), 5.3% (P = 0.0002), 3.4% (P = 0.0002), and 1.2% (P = 0.005) for the rectum, and lower by 10.4% (P = 0.009), 8.3% (P = 0.0004), 5.4% (P = 0.0003), and 2.1% (P = 0.003) for the anterior half rectum. Significant reductions of dose to the rectum using ERB were observed. This may lead to improvement of the rectal toxicity profiles in prostate SBRT. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Prediction of Radiation Esophagitis in Non–Small Cell Lung Cancer Using Clinical Factors, Dosimetric Parameters, and Pretreatment Cytokine Levels

Directory of Open Access Journals (Sweden)

Peter G. Hawkins

2018-02-01

Full Text Available Radiation esophagitis (RE is a common adverse event associated with radiotherapy for non–small cell lung cancer (NSCLC. While plasma cytokine levels have been correlated with other forms of radiation-induced toxicity, their association with RE has been less well studied. We analyzed data from 126 patients treated on 4 prospective clinical trials. Logistic regression models based on combinations of dosimetric factors [maximum dose to 2 cubic cm (D2cc and generalized equivalent uniform dose (gEUD], clinical variables, and pretreatment plasma levels of 30 cytokines were developed. Cross-validated estimates of area under the receiver operating characteristic curve (AUC and log likelihood were used to assess prediction accuracy. Dose-only models predicted grade 3 RE with AUC values of 0.750 (D2cc and 0.727 (gEUD. Combining clinical factors with D2cc increased the AUC to 0.779. Incorporating pretreatment cytokine measurements, modeled as direct associations with RE and as potential interactions with the dose-esophagitis association, produced AUC values of 0.758 and 0.773, respectively. D2cc and gEUD correlated with grade 3 RE with odds ratios (ORs of 1.094/Gy and 1.096/Gy, respectively. Female gender was associated with a higher risk of RE, with ORs of 1.09 and 1.112 in the D2cc and gEUD models, respectively. Older age was associated with decreased risk of RE, with ORs of 0.992/year and 0.991/year in the D2cc and gEUD models, respectively. Combining clinical with dosimetric factors but not pretreatment cytokine levels yielded improved prediction of grade 3 RE compared to prediction by dose alone. Such multifactorial modeling may prove useful in directing radiation treatment planning.

Optimal Patient Positioning (Prone Versus Supine) for VMAT in Gynecologic Cancer: A Dosimetric Study on the Effect of Different Margins

Energy Technology Data Exchange (ETDEWEB)

Heijkoop, Sabrina T., E-mail: s.heijkoop@erasmusmc.nl [Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands); Westerveld, Henrike; Bijker, Nina [Department of Radiation Oncology, Academic Medical Center, Amsterdam (Netherlands); Feije, Raphael; Sharfo, Abdul W. [Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands); Wieringen, Niek van [Department of Radiation Oncology, Academic Medical Center, Amsterdam (Netherlands); Mens, Jan Willem M. [Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands); Stalpers, Lukas J.A. [Department of Radiation Oncology, Academic Medical Center, Amsterdam (Netherlands); Hoogeman, Mischa S. [Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands)

2016-10-01

Purpose/Objective: It is unknown whether the historically found dosimetric advantages of treating gynecologic cancer with the patient in a prone position with use of a small-bowel displacement device (belly-board) remain when volumetric arc therapy (VMAT) is used and whether these advantages depend on the necessary margin between clinical target volume (CTV) and planning target volume (PTV). The aim of this study is to determine the best patient position (prone or supine) in terms of sparing organs at risk (OAR) for various CTV-to-PTV margins and VMAT dose delivery. Methods and Materials: In an institutional review board—approved study, 26 patients with gynecologic cancer scheduled for primary (9) or postoperative (17) radiation therapy were scanned in a prone position on a belly-board and in a supine position on the same day. The primary tumor CTV, nodal CTV, bladder, bowel, and rectum were delineated on both scans. The PTVs were created each with a different margin for the primary tumor and nodal CTV. The VMAT plans were generated with our in-house system for automated treatment planning. For all margin combinations, the supine and prone plans were compared with consideration of all OAR dose-volume parameters but with highest priority given to bowel cavity V{sub 45Gy} (cm{sup 3}). Results: For both groups, the prone position reduced the bowel cavity V{sub 45Gy}, in particular for nodal margins ≥10 mm (ΔV{sub 45Gy} = 23.9 ± 10.6 cm{sup 3}). However, for smaller margins, the advantage was much less pronounced (ΔV{sub 45Gy} = 6.5 ± 3.0 cm{sup 3}) and did not reach statistical significance. The rectum mean dose (D{sub mean}) was significantly lower (ΔD{sub mean} = 2.5 ± 0.3 Gy) in the prone position for both patient groups and for all margins, and the bladder D{sub mean} was significantly lower in the supine position (ΔD{sub mean} = 2.6 ± 0.4 Gy) only for the postoperative group. The advantage of the prone position was not present if it

A treatment planning comparison between modulated tri-cobalt-60 teletherapy and linear accelerator–based stereotactic body radiotherapy for central early-stage non−small cell lung cancer

Energy Technology Data Exchange (ETDEWEB)

Merna, Catherine; Rwigema, Jean-Claude M.; Cao, Minsong; Wang, Pin-Chieh; Kishan, Amar U.; Michailian, Argin; Lamb, James; Sheng, Ke; Agazaryan, Nzhde; Low, Daniel A.; Kupelian, Patrick; Steinberg, Michael L.; Lee, Percy, E-mail: percylee@mednet.ucla.edu

2016-04-01

We evaluated the feasibility of planning stereotactic body radiotherapy (SBRT) for large central early-stage non−small cell lung cancer with a tri-cobalt-60 (tri-{sup 60}Co) system equipped with real-time magnetic resonance imaging (MRI) guidance, as compared to linear accelerator (LINAC)–based SBRT. In all, 20 patients with large central early-stage non−small cell lung cancer who were treated between 2010 and 2015 with LINAC-based SBRT were replanned using a tri-{sup 60}Co system for a prescription dose of 50 Gy in 4 fractions. Doses to organs at risk were evaluated based on established MD Anderson constraints for central lung SBRT. R{sub 100} values were calculated as the total tissue volume receiving 100% of the dose (V{sub 100}) divided by the planning target volume and compared to assess dose conformity. Dosimetric comparisons between LINAC-based and tri-{sup 60}Co SBRT plans were performed using Student's t-test and Wilcoxon Ranks test. Blinded reviews by radiation oncologists were performed to assess the suitability of both plans for clinical delivery. The mean planning target volume was 48.3 cc (range: 12.1 to 139.4 cc). Of the tri-{sup 60}Co SBRT plans, a mean 97.4% of dosimetric parameters per patient met MD Anderson dose constraints, whereas a mean 98.8% of dosimetric parameters per patient were met with LINAC-based SBRT planning (p = 0.056). R{sub 100} values were similar between both plans (1.20 vs 1.21, p = 0.79). Upon blinded review by 4 radiation oncologists, an average of 90% of the tri-{sup 60}Co SBRT plans were considered acceptable for clinical delivery compared with 100% of the corresponding LINAC-based SBRT plans (p = 0.17). SBRT planning using the tri-{sup 60}Co system with built-in MRI is feasible and achieves clinically acceptable plans for most central lung patients, with similar target dose conformity and organ at risk dosimetry. The added benefit of real-time MRI-guided therapy may further optimize tumor targeting while

A treatment planning comparison between modulated tri-cobalt-60 teletherapy and linear accelerator-based stereotactic body radiotherapy for central early-stage non-small cell lung cancer.

Science.gov (United States)

Merna, Catherine; Rwigema, Jean-Claude M; Cao, Minsong; Wang, Pin-Chieh; Kishan, Amar U; Michailian, Argin; Lamb, James; Sheng, Ke; Agazaryan, Nzhde; Low, Daniel A; Kupelian, Patrick; Steinberg, Michael L; Lee, Percy

2016-01-01

We evaluated the feasibility of planning stereotactic body radiotherapy (SBRT) for large central early-stage non-small cell lung cancer with a tri-cobalt-60 (tri-(60)Co) system equipped with real-time magnetic resonance imaging (MRI) guidance, as compared to linear accelerator (LINAC)-based SBRT. In all, 20 patients with large central early-stage non-small cell lung cancer who were treated between 2010 and 2015 with LINAC-based SBRT were replanned using a tri-(60)Co system for a prescription dose of 50Gy in 4 fractions. Doses to organs at risk were evaluated based on established MD Anderson constraints for central lung SBRT. R100 values were calculated as the total tissue volume receiving 100% of the dose (V100) divided by the planning target volume and compared to assess dose conformity. Dosimetric comparisons between LINAC-based and tri-(60)Co SBRT plans were performed using Student׳s t-test and Wilcoxon Ranks test. Blinded reviews by radiation oncologists were performed to assess the suitability of both plans for clinical delivery. The mean planning target volume was 48.3cc (range: 12.1 to 139.4cc). Of the tri-(60)Co SBRT plans, a mean 97.4% of dosimetric parameters per patient met MD Anderson dose constraints, whereas a mean 98.8% of dosimetric parameters per patient were met with LINAC-based SBRT planning (p = 0.056). R100 values were similar between both plans (1.20 vs 1.21, p = 0.79). Upon blinded review by 4 radiation oncologists, an average of 90% of the tri-(60)Co SBRT plans were considered acceptable for clinical delivery compared with 100% of the corresponding LINAC-based SBRT plans (p = 0.17). SBRT planning using the tri-(60)Co system with built-in MRI is feasible and achieves clinically acceptable plans for most central lung patients, with similar target dose conformity and organ at risk dosimetry. The added benefit of real-time MRI-guided therapy may further optimize tumor targeting while improving normal tissue sparing, which warrants further

Dosimetric verification of IMRT plans

International Nuclear Information System (INIS)

Bulski, W.; Cheimicski, K.; Rostkowska, J.

2012-01-01

Intensity modulated radiotherapy (IMRT) is a complex procedure requiring proper dosimetric verification. IMRT dose distributions are characterized by steep dose gradients which enable to spare organs at risk and allow for an escalation of the dose to the tumor. They require large number of radiation beams (sometimes over 10). The fluence measurements for individual beams are not sufficient for evaluation of the total dose distribution and to assure patient safety. The methods used at the Centre of Oncology in Warsaw are presented. In order to measure dose distributions in various cross-sections the film dosimeters were used (radiographic Kodak EDR2 films and radiochromic Gafchromic EBT films). The film characteristics were carefully examined. Several types of tissue equivalent phantoms were developed. A methodology of comparing measured dose distributions against the distributions calculated by treatment planning systems (TPS) was developed and tested. The tolerance level for this comparison was set at 3% difference in dose and 3 mm in distance to agreement. The so called gamma formalism was used. The results of these comparisons for a group of over 600 patients are presented. Agreement was found in 87 % of cases. This film dosimetry methodology was used as a benchmark to test and validate the performance of commercially available 2D and 3D matrices of detectors (ionization chambers or diodes). The results of these validations are also presented. (authors)

Investigation of dosimetric characteristics of the high sensitivity LiF:Mg,Cu,P Thermoluminescent Dosemeter and its applications in diagnostic radiology - a review

International Nuclear Information System (INIS)

Fung, K.L.

2004-01-01

This study investigated the dosimetric properties of the high sensitivity TLD (Thermoluminescent Dosemeter) of LiF:Mg,Cu,P and its applications in diagnostic radiology. A reproducible readout and annealing regime for this high sensitivity TLD was developed in the initial part of this study with the newly installed automatic TLD Reader system. Basic dosimetric characteristics of this T.L. dosemeter were then investigated. This paved the foundation for subsequent selected novel application studies in diagnostic radiology. This study exploits the favourable dosimetric properties of these T.L. dosemeters in some selected novel dosimetric applications in diagnostic radiology with an anthropomorphic phantom. The applications studied in radiological procedures included: dose reduction in lumbar spine radiography utilizing the 'anode heel effect'; gonad dose variation with kV p in chest radiography; foetal dose comparison between computed tomography (CT) and computed radiography (CR) in X-ray pelvimetry; lens dose reduction with bismuth eye-shields in CT brain studies; foetal dose assessment of early pregnancy in common high risk radiological examinations. It is anticipated that the unique and favourable dosimetric performance of LiF:Mg,Cu,P T.L. phosphor will be exploited further in measurements of low level dose received by patients and staff in diagnostic radiological procedures such as paediatric X-ray examinations

Investigation of dosimetric characteristics of the high sensitivity LiF:Mg,Cu,P Thermoluminescent Dosemeter and its applications in diagnostic radiology - a review

Energy Technology Data Exchange (ETDEWEB)

Fung, K.L. E-mail: orkarl@polyu.edu.hk

2004-05-01

This study investigated the dosimetric properties of the high sensitivity TLD (Thermoluminescent Dosemeter) of LiF:Mg,Cu,P and its applications in diagnostic radiology. A reproducible readout and annealing regime for this high sensitivity TLD was developed in the initial part of this study with the newly installed automatic TLD Reader system. Basic dosimetric characteristics of this T.L. dosemeter were then investigated. This paved the foundation for subsequent selected novel application studies in diagnostic radiology. This study exploits the favourable dosimetric properties of these T.L. dosemeters in some selected novel dosimetric applications in diagnostic radiology with an anthropomorphic phantom. The applications studied in radiological procedures included: dose reduction in lumbar spine radiography utilizing the 'anode heel effect'; gonad dose variation with kV{sub p} in chest radiography; foetal dose comparison between computed tomography (CT) and computed radiography (CR) in X-ray pelvimetry; lens dose reduction with bismuth eye-shields in CT brain studies; foetal dose assessment of early pregnancy in common high risk radiological examinations. It is anticipated that the unique and favourable dosimetric performance of LiF:Mg,Cu,P T.L. phosphor will be exploited further in measurements of low level dose received by patients and staff in diagnostic radiological procedures such as paediatric X-ray examinations.

Initial Report of Pencil Beam Scanning Proton Therapy for Posthysterectomy Patients With Gynecologic Cancer

Energy Technology Data Exchange (ETDEWEB)

Lin, Lilie L., E-mail: lin@xrt.upenn.edu; Kirk, Maura; Scholey, Jessica; Taku, Nicolette; Kiely, Janid B.; White, Benjamin; Both, Stefan

2016-05-01

Purpose: To report the acute toxicities associated with pencil beam scanning proton beam radiation therapy (PBS) for whole pelvis radiation therapy in women with gynecologic cancers and the results of a dosimetric comparison of PBS versus intensity modulated radiation therapy (IMRT) plans. Methods and Materials: Eleven patients with posthysterectomy gynecologic cancer received PBS to the whole pelvis. The patients received a dose of 45 to 50.4 Gy relative biological effectiveness (RBE) in 1.8 Gy (RBE) daily fractions. Acute toxicity was scored according to the Common Terminology Criteria for Adverse Events, version 4. A dosimetric comparison between a 2-field posterior oblique beam PBS and an IMRT plan was conducted. The Wilcoxon signed rank test was used to assess the potential dosimetric differences between the 2 plans and PBS target coverage robustness relative to setup uncertainties. Results: The median patient age was 55 years (range 23-76). The primary site was cervical in 7, vaginal in 1, and endometrial in 3. Of the 11 patients, 7 received concurrent cisplatin, 1 each received sandwich carboplatin and paclitaxel chemotherapy, both sandwich and concurrent chemotherapy, and concurrent and adjuvant chemotherapy, and 1 received no chemotherapy. All patients completed treatment. Of the 9 patients who received concurrent chemotherapy, the rate of grade 2 and 3 hematologic toxicities was 33% and 11%, respectively. One patient (9%) developed grade 3 acute gastrointestinal toxicity; no patient developed grade ≥3 genitourinary toxicity. The volume of pelvic bone marrow, bladder, and small bowel receiving 10 to 30 Gy was significantly lower with PBS than with intensity modulated radiation therapy (P<.001). The target coverage for all PBS plans was robust relative to the setup uncertainties (P>.05) with the clinical target volume mean dose percentage received by 95% and 98% of the target volume coverage changes within 2% for the individual plans. Conclusions: Our

Hot pixel generation in active pixel sensors: dosimetric and micro-dosimetric response

Science.gov (United States)

Scheick, Leif; Novak, Frank

2003-01-01

The dosimetric response of an active pixel sensor is analyzed. heavy ions are seen to damage the pixel in much the same way as gamma radiation. The probability of a hot pixel is seen to exhibit behavior that is not typical with other microdose effects.

Dosimetric aspects of the treatment of metastatic bone pain with radiopharmaceuticals

International Nuclear Information System (INIS)

Garcia, T.; Marti, J. F.; Olivas, C.; Vercher, J. L.; Repetto, R.; Bello, P.

2014-01-01

Within the context of treatment of metastatic bone pain with bone seeking radiopharmaceuticals, this paper expounds the results of an analysis of available molecules (both approved for clinical use or still under study) intended to obtain a detailed comparison of their dosimetric characteristics. These can be used to supplement the list of already know differences between them, such as efficacy, appearance and length of the palliative effect, eventual tumoricidal effect, myelotoxicity, sale price and availability. Seven radiopharmaceuticals have been analysed, five of them are based on beta emission radionuclides: 3 2P, 1 53Sm, 1 86Re and 1 88Re and the other two ones are based on high Linear energy Transference emission radionuclides: 1 17mSn and 2 23Ra a series of estimates of the main dosimetric parameters for each radiopharmaceutical analysed have been obtained. The values obtained might be worth being incorporated to the risk/benefit analysis that precedes every choice of the specific radiopharmaceutical to be used with an individual patient. In this way, we hope these results will be of some help for those Nuclear Medicine specialists interested in the treatment of oncological bone pathologies. (Author)

Stereotactic body radiation therapy planning with duodenal sparing using volumetric-modulated arc therapy vs intensity-modulated radiation therapy in locally advanced pancreatic cancer: A dosimetric analysis

Energy Technology Data Exchange (ETDEWEB)

Kumar, Rachit; Wild, Aaron T.; Ziegler, Mark A.; Hooker, Ted K.; Dah, Samson D.; Tran, Phuoc T.; Kang, Jun; Smith, Koren; Zeng, Jing [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins Hospital, 401N. Broadway, Weinberg Suite 1440, Baltimore, MD 21231 (United States); Pawlik, Timothy M. [Department of Surgery, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD (United States); Tryggestad, Erik [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins Hospital, 401N. Broadway, Weinberg Suite 1440, Baltimore, MD 21231 (United States); Ford, Eric [Department of Radiation Oncology, Fred Hutchinson Cancer Center, University of Washington, Seattle, WA (United States); Herman, Joseph M., E-mail: jherma15@jhmi.edu [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins Hospital, 401N. Broadway, Weinberg Suite 1440, Baltimore, MD 21231 (United States)

2013-10-01

Stereotactic body radiation therapy (SBRT) achieves excellent local control for locally advanced pancreatic cancer (LAPC), but may increase late duodenal toxicity. Volumetric-modulated arc therapy (VMAT) delivers intensity-modulated radiation therapy (IMRT) with a rotating gantry rather than multiple fixed beams. This study dosimetrically evaluates the feasibility of implementing duodenal constraints for SBRT using VMAT vs IMRT. Non–duodenal sparing (NS) and duodenal-sparing (DS) VMAT and IMRT plans delivering 25 Gy in 1 fraction were generated for 15 patients with LAPC. DS plans were constrained to duodenal D{sub max} of<30 Gy at any point. VMAT used 1 360° coplanar arc with 4° spacing between control points, whereas IMRT used 9 coplanar beams with fixed gantry positions at 40° angles. Dosimetric parameters for target volumes and organs at risk were compared for DS planning vs NS planning and VMAT vs IMRT using paired-sample Wilcoxon signed rank tests. Both DS VMAT and DS IMRT achieved significantly reduced duodenal D{sub mean}, D{sub max}, D{sub 1cc}, D{sub 4%}, and V{sub 20} {sub Gy} compared with NS plans (all p≤0.002). DS constraints compromised target coverage for IMRT as demonstrated by reduced V{sub 95%} (p = 0.01) and D{sub mean} (p = 0.02), but not for VMAT. DS constraints resulted in increased dose to right kidney, spinal cord, stomach, and liver for VMAT. Direct comparison of DS VMAT and DS IMRT revealed that VMAT was superior in sparing the left kidney (p<0.001) and the spinal cord (p<0.001), whereas IMRT was superior in sparing the stomach (p = 0.05) and the liver (p = 0.003). DS VMAT required 21% fewer monitor units (p<0.001) and delivered treatment 2.4 minutes faster (p<0.001) than DS IMRT. Implementing DS constraints during SBRT planning for LAPC can significantly reduce duodenal point or volumetric dose parameters for both VMAT and IMRT. The primary consequence of implementing DS constraints for VMAT is increased dose to other organs at

Dosimetric characterization of a 2-D array of 223 solid state detectors for daily morning checks in Tomo Therapy equipment

International Nuclear Information System (INIS)

Reyes S, U.; Sosa A, M.; Vega C, H. R.

2015-10-01

Tomo Therapy is a new technique for the cancer treatment; however, the equipment must meet nearly all mechanical and dosimetric characteristics of a conventional linear accelerator for medical use. Daily quality controls are vital to the good operation of the equipment and thus guarantee excellent quality in the daily delivery of treatments. This paper presents the procedure of the dosimetric characterization of a two-dimensional array of 223 solid state detectors, called TomoDose of the Sun Nuclear Company. Dosimetric important criteria are established to perform these checks quickly and accurately. Dosimetric tests proposed are: repeatability, linearity, dependence of Sad and SSD. Some results are compared with readings of the ionization chamber Exradim A1SL. Finally the results of 30 consecutive days are presented to establish criteria for evidence of dose, field size, symmetry and flattening of the radiation beam on Tomo Therapy equipment. Expected values for daily verification are: Dose constancy of 194.89 c Gy, σ= 1.31 c Gy, symmetry in the X axis of -0.19 %, σ=0.08 %, symmetry in the Y axis of 1.66 %, σ= 0.05 %, flattened in the X axis of 25.71 %, σ= 0.05 % and flattened in the Y axis of 6.41 %, σ= 10.23 %. Field sizes obtained were 40.45 cm in the X axis and 5.10 on the Y axis, with standard deviations of 0.02 cm and 0.01 cm, respectively. TomoDose dosimetric values, compared to the values obtained with ionization chamber, presented differences smaller than 2%. (Author)

Balloon-based adjuvant radiotherapy in breast cancer: comparison between {sup 99m}Tc and HDR {sup 192}Ir

Energy Technology Data Exchange (ETDEWEB)

Campos, Tarcisio Passos Ribeiro de; Lima, Carla Flavia de; Cuperschmid, Ethel Mizrahy, E-mail: tprcampos@pq.cnpq.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

2016-03-15

Objective: To perform a comparative dosimetric analysis, based on computer simulations, of temporary balloon implants with {sup 99m}Tc and balloon brachytherapy with high-dose-rate (HDR) {sup 192}Ir, as boosts to radiotherapy. We hypothesized that the two techniques would produce equivalent doses under pre-established conditions of activity and exposure time. Materials and methods: simulations of implants with {sup 99m}Tc-filled and HDR {sup 192}Ir-filled balloons were performed with the Siscodes/MCNP5, modeling in voxels a magnetic resonance imaging set related to a young female. Spatial dose rate distributions were determined. In the dosimetric analysis of the protocols, the exposure time and the level of activity required were specified. Results: the {sup 99m}Tc balloon presented a weighted dose rate in the tumor bed of 0.428 cGy.h{sup -1}.mCi{sup -1} and 0.190 cGyh{sup -1} at the balloon surface and at 8-10 mm from the surface, respectively, compared with 0.499 and 0.150 cGyh{sup -1}.mCi{sup -1}, respectively, for the HDR {sup 192}Ir balloon. An exposure time of 24 hours was required for the {sup 99m}Tc balloon to produce a boost of 10.14 Gy with 1.0 Ci, whereas only 24 minutes with 10.0 Ci segments were required for the HDR {sup 192}Ir balloon to produce a boost of 5.14 Gy at the same reference point, or 10.28 Gy in two 24-minutes fractions. Conclusion: temporary {sup 99m}Tc balloon implantation is an attractive option for adjuvant radiotherapy in breast cancer, because of its availability, economic viability, and similar dosimetry in comparison with the use of HDR {sup 192}Ir balloon implantation, which is the current standard in clinical practice. (author)

A Comparison of Soft-Tissue Implanted Markers and Bony Anatomy Alignments for Image-Guided Treatments of Head-and-Neck Cancers

International Nuclear Information System (INIS)

Zeidan, Omar A.; Huddleston, Adam J.; Lee, Choonik; Langen, Katja M.; Kupelian, Patrick A.; Meeks, Sanford L.; Manon, Rafael R.

2010-01-01

Purpose: To compare the geometric alignments of soft-tissue implanted markers to the traditional bony-based alignments in head-and-neck cancers, on the basis of daily image guidance. Dosimetric impact of the two alignment techniques on target coverage is presented. Methods and Materials: A total of 330 retrospective alignments (5 patients) were performed on daily megavoltage computed tomography (MVCT) image sets using both alignment techniques. Intermarker distances were tracked for all fractions to assess marker interfractional stability. Using a deformable image registration algorithm, target cumulative doses were calculated according to generated shifts on daily MVCT image sets. Target D95 was used as a dosimetric endpoint to evaluate each alignment technique. Results: Intermarker distances overall were stable, with a standard deviation of <1.5 mm for all fractions and no observed temporal trends. Differences in shift magnitudes between both alignment techniques were found to be statistically significant, with a maximum observed difference of 8 mm in a given direction. Evaluation of technique-specific dose coverage based on D95 of target clinical target volume and planning target volume shows small differences (within ±5%) compared with the kilovoltage CT plan. Conclusion: The use of daily MVCT imaging demonstrates that implanted markers in oral tongue and soft-palate cancers are stable localization surrogates. Alignments based on implanted markers generate shifts comparable overall to the traditional bony-based alignment, with no observed systematic difference in magnitude or direction. The cumulative dosimetric impact on target clinical target volume and planning target volume coverage was found to be similar, despite large observed differences in daily alignment shifts between the two techniques.

Establishment of a dosimetric system for high doses using glasses

International Nuclear Information System (INIS)

Correa Quezada, Valeria de la Asuncion

1997-01-01

A routine dosimetric system was developed using commercial glass samples. The dosimetric characteristics of national and imported samples were studied: batch uniformity, response repeatability, reutilization, absorbed dose response, detection range, response stability as a function of absorbed dose, storage temperature and thermal treatments pre- and post-irradiation, using the optical absorption technique. As an application, the dosimetric system was tested in a flower irradiation process at IPEN. All the obtained results show the usefulness of the proposed system for high dose dosimetry. (author)

Dosimetric behavior of thermoluminescent dosimeters at low doses in diagnostic radiology

International Nuclear Information System (INIS)

Del Sol F, S.; Garcia S, R.; Guzman M, J.; Sanchez G, D.; Rivera M, T.; Ramirez R, G.; Gaona, E.

2015-10-01

Thermoluminescent (Tl) characteristics of TLD-100, LiF:Mg,Cu,P, and CaSO 4 : Dy the under homogeneous field of X-ray beams of diagnostic irradiation and its verification using thermoluminescent dosimetry is presented. The irradiations were performed utilizing an X-ray beam generated by a Radiology Mexican Company: MRH-II E GMX 325-AF SBV-1 model, with Rotating Anode X-Ray Tube installed in the Hospital Juarez Norte de Mexico in Mexico City. Different thermoluminescent characteristics of dosimetric material were studied, such as, batch homogeneity, Tl glow curve, Tl response as a function of X-ray dose, reproducibility and fading. Materials were calibrated in terms of absorbed dose to the standard calibration distance and positioned in a generic Phantom was used. Dose verification and comparison with the measurements made with that obtained by TLD-100 were analyzed. Preliminary results indicate the dosimetric peak appears at 243, 236 and 277 ± 5 degrees C respectively, these peaks are in agreement with that reported in the literature. Tl glow curve as a function of X-ray dose showed a linearity in the range from 1.76 mGy up to 14.70 mGy for all materials. Fading for a period of one month at room temperature showed low fading LiF:Mg,Cu,P, medium and high for TLD-100 and CaSO 4 : Dy. The results suggest that the three materials are suitable for measurements at low doses in radiodiagnostic, however, for its dosimetric characteristics are most effective for individual applications: personal dosimetry and monitors limb (LiF:Mg,Cu,P), clinical dosimetry and environmental (TLD-100 and CaSO 4 : Dy). (Author)

Models for comparing lung-cancer risks in radon- and plutonium-exposed experimental animals

International Nuclear Information System (INIS)

Gilbert, E.S.; Cross, F.T.; Sanders, C.L.; Dagle, G.E.

1990-10-01

Epidemiologic studies of radon-exposed underground miners have provided the primary basis for estimating human lung-cancer risks resulting from radon exposure. These studies are sometimes used to estimate lung-cancer risks resulting from exposure to other alpha- emitters as well. The latter use, often referred to as the dosimetric approach, is based on the assumption that a specified dose to the lung produces the same lung-tumor risk regardless of the substance producing the dose. At Pacific Northwest Laboratory, experiments have been conducted in which laboratory rodents have been given inhalation exposures to radon and to plutonium ( 239 PuO 2 ). These experiments offer a unique opportunity to compare risks, and thus to investigate the validity of the dosimetric approach. This comparison is made most effectively by modeling the age-specific risk as a function of dose in a way that is comparable to analyses of human data. Such modeling requires assumptions about whether tumors are the cause of death or whether they are found incidental to death from other causes. Results based on the assumption that tumors are fatal indicate that the radon and plutonium dose-response curves differ, with a linear function providing a good description of the radon data, and a pure quadratic function providing a good description of the plutonium data. However, results based on the assumption that tumors are incidental to death indicate that the dose-response curves for the two exposures are very similar, and thus support the dosimetric approach. 14 refs., 2 figs., 6 tabs

Intermediate Megavoltage Photon Beams for Improved Lung Cancer Treatments.

Directory of Open Access Journals (Sweden)

Ying Zhang

Full Text Available The goal of this study is to evaluate the effects of intermediate megavoltage (3-MV photon beams on SBRT lung cancer treatments. To start with, a 3-MV virtual beam was commissioned on a commercial treatment planning system based on Monte Carlo simulations. Three optimized plans (6-MV, 3-MV and dual energy of 3- and 6-MV were generated for 31 lung cancer patients with identical beam configuration and optimization constraints for each patient. Dosimetric metrics were evaluated and compared among the three plans. Overall, planned dose conformity was comparable among three plans for all 31 patients. For 21 thin patients with average short effective path length (< 10 cm, the 3-MV plans showed better target coverage and homogeneity with dose spillage index R50% = 4.68±0.83 and homogeneity index = 1.26±0.06, as compared to 4.95±1.01 and 1.31±0.08 in the 6-MV plans (p < 0.001. Correspondingly, the average/maximum reductions of lung volumes receiving 20 Gy (V20Gy, 5 Gy (V5Gy, and mean lung dose (MLD were 7%/20%, 9%/30% and 5%/10%, respectively in the 3-MV plans (p < 0.05. The doses to 5% volumes of the cord, esophagus, trachea and heart were reduced by 9.0%, 10.6%, 11.4% and 7.4%, respectively (p < 0.05. For 10 thick patients, dual energy plans can bring dosimetric benefits with comparable target coverage, integral dose and reduced dose to the critical structures, as compared to the 6-MV plans. In conclusion, our study indicated that 3-MV photon beams have potential dosimetric benefits in treating lung tumors in terms of improved tumor coverage and reduced doses to the adjacent critical structures, in comparison to 6-MV photon beams. Intermediate megavoltage photon beams (< 6-MV may be considered and added into current treatment approaches to reduce the adjacent normal tissue doses while maintaining sufficient tumor dose coverage in lung cancer radiotherapy.

Dosimetric management during a criticality accident

International Nuclear Information System (INIS)

Lebaron-Jacobs, L.; Fottorino, R.; Racine, Y.; Miele, A.; Barbry, F.; Briot, F.; Distinguin, S.; Le Goff, J.P.; Berard, P.; Boisson, P.; Cavadore, D.; Lecoix, G.; Persico, M.H.; Rongier, E.; Challeton-De Vathaire, C.; Medioni, R.; Voisin, P.; Exmelin, L.; Flury-Herard, A.; Gaillard-Lecanu, E.; Lemaire, G.; Gonin, M.; Riasse, C.

2008-01-01

A working group from health occupational and clinical biochemistry services on French sites has issued essential data sheets on the guidelines to follow in managing the victims of a criticality accident. Since the priority of the medical management after a criticality accident is to assess the dose and the distribution of dose, some dosimetric investigations have been selected in order to provide a prompt response and to anticipate the final dose reconstruction. Comparison exercises between clinical biochemistry laboratories on French sites were carried out to confirm that each laboratory maintained the required operational methods for hair treatment and the appropriate equipment for 32 P activity in hair and 24 Na activity in blood measurements, and to demonstrate its ability to rapidly provide neutron dose estimates after a criticality accident. As a result, a relation has been assessed to estimate the dose and the distribution of dose according to the neutron spectrum following a criticality accident. (authors)

SU-F-SPS-04: Dosimetric Evaluation of the Dose Calculation Accuracy of Different Algorithms for Two Different Treatment Techniques During Whole Breast Irradiation

Energy Technology Data Exchange (ETDEWEB)

Pacaci, P; Cebe, M; Mabhouti, H; Codel, G; Serin, E; Sanli, E; Kucukmorkoc, E; Doyuran, M; Kucuk, N; Canoglu, D; Altinok, A; Acar, H; Caglar Ozkok, H [Medipol University, Istanbul, Istanbul (Turkey)

2016-06-15

Purpose: In this study, dosimetric comparison of field in field (FIF) and intensity modulated radiation therapy (IMRT) techniques used for treatment of whole breast radiotherapy (WBRT) were made. The dosimetric accuracy of treatment planning system (TPS) for Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) algorithms in predicting PTV and OAR doses was also investigated. Methods: Two different treatment planning techniques of left-sided breast cancer were generated for rando phantom. FIF and IMRT plans were compared for doses in PTV and OAR volumes including ipsilateral lung, heart, left ascending coronary artery, contralateral lung and the contralateral breast. PTV and OARs doses and homogeneity and conformality indexes were compared between two techniques. The accuracy of TPS dose calculation algorithms was tested by comparing PTV and OAR doses measured by thermoluminescent dosimetry with the dose calculated by the TPS using AAA and AXB for both techniques. Results: IMRT plans had better conformality and homogeneity indexes than FIF technique and it spared OARs better than FIF. While both algorithms overestimated PTV doses they underestimated all OAR doses. For IMRT plan, PTV doses, overestimation up to 2.5 % was seen with AAA algorithm but it decreased to 1.8 % when AXB algorithm was used. Based on the results of the anthropomorphic measurements for OAR doses, underestimation greater than 7 % is possible by the AAA. The results from the AXB are much better than the AAA algorithm. However, underestimations of 4.8 % were found in some of the points even for AXB. For FIF plan, similar trend was seen for PTV and OARs doses in both algorithm. Conclusion: When using the Eclipse TPS for breast cancer, AXB the should be used instead of the AAA algorithm, bearing in mind that the AXB may still underestimate all OAR doses.

Analysis of clinical and dosimetric factors associated with treatment-related pneumonitis (TRP) in patients with non-small-cell lung cancer (NSCLC) treated with concurrent chemotherapy and three-dimensional conformal radiotherapy (3D-CRT)

International Nuclear Information System (INIS)

Wang Shulian; Liao Zhongxing; Wei Xiong; Liu, Helen H.; Tucker, Susan L.; Hu Chaosu; Mohan, Rodhe; Cox, James D.; Komaki, Ritsuko

2006-01-01

Purpose: To investigate factors associated with treatment-related pneumonitis in non-small-cell lung cancer patients treated with concurrent chemoradiotherapy. Patients and Methods: We retrospectively analyzed data from 223 patients treated with definitive concurrent chemoradiotherapy. Treatment-related pneumonitis was graded according to Common Terminology Criteria for Adverse Events version 3.0. Univariate and multivariate analyses were performed to identify predictive factors. Results: Median follow-up was 10.5 months (range, 1.4-58 months). The actuarial incidence of Grade ≥3 pneumonitis was 22% at 6 months and 32% at 1 year. By univariate analyses, lung volume, gross tumor volume, mean lung dose, and relative V5 through V65, in increments of 5 Gy, were all found to be significantly associated with treatment-related pneumonitis. The mean lung dose and rV5-rV65 were highly correlated (p 42% were 3% and 38%, respectively (p = 0.001). Conclusions: In this study, a number of clinical and dosimetric factors were found to be significantly associated with treatment-related pneumonitis. However, rV5 was the only significant factor associated with this toxicity. Until it is better understood which dose range is most relevant, multiple clinical and dosimetric factors should be considered in treatment planning for non-small-cell lung cancer patients receiving concurrent chemoradiotherapy

Development of the Nation-Wide Dosimetric Monitoring Network in Ukraine

International Nuclear Information System (INIS)

Chumak, V.; Boguslavskaya, A.; Musijachenko, A.

2004-01-01

Development of the nation-wide network for monitoring and registration of individual doses is being in progress in Ukraine. The need for urgent action is caused by the fact, that despite wide use of nuclear energy and radiation sources in industry and medicine, there is no centralized dose accounting system in Ukraine, existing dosimetry services operate obsolete manual TLD readers and no methodological unity is observed by the dosimetry services. Presently the mixed dosimetric monitoring is practiced in Ukraine. Nuclear power plants and some major nuclear facilities have their own dosimetry services responsible for dosimetric monitoring of workers. Rest of occupationally exposed persons is monitored by territorial dosimetry laboratories affiliated to sanitary and epidemiology supervision bodies. In total these services cover about 38,000 occupationally exposed workers, including 5,500 in medicine, 16,400 employees of five nuclear power plants and about 16,000 workers dealing with other sources of occupational exposure (industry, research, military). It is prescribed by the governmental decree that three-level united state system assigned to covering all aspects of efficient dosimetric monitoring should be established. The tasks of the system, in particular, are: securing methodical unity of individual dosimetric monitoring; scientific and methodological guidance of individual dosimetric control; procurement of common technical policy regarding nomenclature and operation of instrumentation; implementation of quality assurance programs; development and support of information infrastructure for logging, storage and access to data on individual dosimetric monitoring, in particular - keeping the national registry of individual doses; training and certification of personnel engaged in the system of individual dosimetric monitoring. In its development, the national system will be guided by international experience and will be established according to the best practices

Prospective assessment of dosimetric/physiologic-based models for predicting radiation pneumonitis

International Nuclear Information System (INIS)

Kocak, Zafer; Borst, Gerben R.; Zeng Jing; Zhou Sumin; Hollis, Donna R.; Zhang Junan; Evans, Elizabeth S.; Folz, Rodney J.; Wong, Terrence; Kahn, Daniel; Belderbos, Jose S.A.; Lebesque, Joos V.; Marks, Lawrence B.

2007-01-01

Purpose: Clinical and 3D dosimetric parameters are associated with symptomatic radiation pneumonitis rates in retrospective studies. Such parameters include: mean lung dose (MLD), radiation (RT) dose to perfused lung (via SPECT), and pre-RT lung function. Based on prior publications, we defined pre-RT criteria hypothesized to be predictive for later development of pneumonitis. We herein prospectively test the predictive abilities of these dosimetric/functional parameters on 2 cohorts of patients from Duke and Netherlands Cancer Institute (NKI). Methods and Materials: For the Duke cohort, 55 eligible patients treated between 1999 and 2005 on a prospective IRB-approved study to monitor RT-induced lung injury were analyzed. A similar group of patients treated at the NKI between 1996 and 2002 were identified. Patients believed to be at high and low risk for pneumonitis were defined based on: (1) MLD; (2) OpRP (sum of predicted perfusion reduction based on regional dose-response curve); and (3) pre-RT DLCO. All doses reflected tissue density heterogeneity. The rates of grade ≥2 pneumonitis in the 'presumed' high and low risk groups were compared using Fisher's exact test. Results: In the Duke group, pneumonitis rates in patients prospectively deemed to be at 'high' vs. 'low' risk are 7 of 20 and 9 of 35, respectively; p = 0.33 one-tailed Fisher's. Similarly, comparable rates for the NKI group are 4 of 21 and 6 of 44, respectively, p = 0.41 one-tailed Fisher's. Conclusion: The prospective model appears unable to accurately segregate patients into high vs. low risk groups. However, considered retrospectively, these data are consistent with prior studies suggesting that dosimetric (e.g., MLD) and functional (e.g., PFTs or SPECT) parameters are predictive for RT-induced pneumonitis. Additional work is needed to better identify, and prospectively assess, predictors of RT-induced lung injury

Computerized dosimetric system for studying radiation fields of afterloading apparatus

International Nuclear Information System (INIS)

Andryushin, O.S.; Gorshkov, M.I.

1988-01-01

Works on designing a computerized dosimetric scanner (CODOS) for studying radiation fields of remote therapeutic apparatus, providing dosimetric data input from semiconductor transducers and ionization chambers directly into the computer memory were carried out. The basic problems were to provide reproducibility and accuracy of the initial dosimetric data, formation of the data bank on LUEhV-15M1 accelerator bremsstrahlung and electron radiation fields. An extra problem was to provide isodose curves for manual scheduling of radiotherapy. The 15 VUMS-28-025 complex based on Elektronika-60 computer was chosen as a host computer, photodiodes were used as a semiconductor detector, the 70108 rod chamber and VA-J-18 dosemeters were used as an ionization chamber. The results of studies with the CODOS system have been shown that it meets the dosimetric requirements for therapeutic apparatus

Radiological practices using dosimetric films and electronic dosimeters in F-18 production at cyclotron complex center at IEN/CNEN

International Nuclear Information System (INIS)

Santos, Osvaldir P. dos; Silva, J.C.P.; Silva, Luiz Carlos Reina P. da

2009-01-01

The aim of this work is to evaluate, guide and correct radiological practices based on dose rate values obtained from dosimetric films and electronic dosimeters used by technicians involved in Fluorine-18 production facilities at IEN/CNEN. Standard statistical methods have been used to analyze and to evaluate these results. The comparison between these results is the first step to orient decisions concerning radiological practices. Besides, radiometric routine surveys are under evaluation in order to improve radiological control in these facility areas. The electronic dosimeters provide the technicians immediate reading and this help them take protective action immediately. So the comparison between dosimetric film and electronic dosimeters data will provide information about how the recently employed electronic dosimeters are being used and what corrections in their practical use are necessary in order to achieve correct practices. In addition the results and observations obtained will be very important to implement possible changes in radiological routine practices in order to optimize them and keep occupationally exposed individuals radiological dose rates, as low as reasonably achievable, according to ALARA principle. (author)

Impact of gantry rotation time on plan quality and dosimetric verification. Volumetric modulated arc therapy (VMAT) vs. intensity modulated radiotherapy (IMRT)

Energy Technology Data Exchange (ETDEWEB)

Pasler, Marlies; Wirtz, Holger; Lutterbach, Johannes [Gemeinschaftspraxis fuer Strahlentherapie Singen-Friedrichshafen, Singen (Germany)

2011-12-15

To compare plan quality criteria and dosimetric accuracy of step-and-shoot intensity-modulated radiotherapy (ss-IMRT) and volumetric modulated arc radiotherapy (VMAT) using two different gantry rotation times. This retrospective planning study based on 20 patients was comprised of 10 prostate cancer (PC) and 10 head and neck (HN) cancer cases. Each plan contained two target volumes: a primary planning target volume (PTV) and a boost volume. For each patient, one ss-IMRT plan and two VMAT plans at 90 s (VMAT90) and 120 s (VMAT120) per arc were generated with the Pinnacle {sup copyright} planning system. Two arcs were provided for the PTV plans and a single arc for boost volumes. Dosimetric verification of the plans was performed using a 2D ionization chamber array placed in a full scatter phantom. VMAT reduced delivery time and monitor units for both treatment sites compared to IMRT. VMAT120 vs. VMAT90 increased delivery time and monitor units in PC plans without improving plan quality. For HN cases, VMAT120 provided comparable organs at risk sparing and better target coverage and conformity than VMAT90. In the VMAT plan verification, an average of 97.1% of the detector points passed the 3 mm, 3% {gamma} criterion, while in IMRT verification it was 98.8%. VMAT90, VMAT120, and IMRT achieved comparable treatment plans. Slower gantry movement in VMAT120 plans only improves dosimetric quality for highly complex targets.

Impact of gantry rotation time on plan quality and dosimetric verification. Volumetric modulated arc therapy (VMAT) vs. intensity modulated radiotherapy (IMRT)

International Nuclear Information System (INIS)

Pasler, Marlies; Wirtz, Holger; Lutterbach, Johannes

2011-01-01

To compare plan quality criteria and dosimetric accuracy of step-and-shoot intensity-modulated radiotherapy (ss-IMRT) and volumetric modulated arc radiotherapy (VMAT) using two different gantry rotation times. This retrospective planning study based on 20 patients was comprised of 10 prostate cancer (PC) and 10 head and neck (HN) cancer cases. Each plan contained two target volumes: a primary planning target volume (PTV) and a boost volume. For each patient, one ss-IMRT plan and two VMAT plans at 90 s (VMAT90) and 120 s (VMAT120) per arc were generated with the Pinnacle copyright planning system. Two arcs were provided for the PTV plans and a single arc for boost volumes. Dosimetric verification of the plans was performed using a 2D ionization chamber array placed in a full scatter phantom. VMAT reduced delivery time and monitor units for both treatment sites compared to IMRT. VMAT120 vs. VMAT90 increased delivery time and monitor units in PC plans without improving plan quality. For HN cases, VMAT120 provided comparable organs at risk sparing and better target coverage and conformity than VMAT90. In the VMAT plan verification, an average of 97.1% of the detector points passed the 3 mm, 3% γ criterion, while in IMRT verification it was 98.8%. VMAT90, VMAT120, and IMRT achieved comparable treatment plans. Slower gantry movement in VMAT120 plans only improves dosimetric quality for highly complex targets.

Correlation of dosimetric parameters obtained with the analytical anisotropic algorithm and toxicity of chest chemoradiation in lung carcinoma

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Cartier, Lysian; Auberdiac, Pierre; Khodri, Mustapha; Malkoun, Nadia [Departement de Radiotherapie, Institut de Cancerologie de la Loire, St-Priest en Jarez (France); Chargari, Cyrus [Service d' Oncologie Radiotherapie, Hopital d' Instruction des Armees du Val-de-Grace, Paris (France); Thorin, Julie [Departement de Sante Publique, Unite de Statistique, Institut de Cancerologie de la Loire, St-Priest en Jarez (France); Melis, Adrien [Departement d' Oncologie Medicale, Institut de Cancerologie de la Loire, St-Priest en Jarez (France); Talabard, Jean-Noeel; Laroche, Guy de [Departement de Radiotherapie, Institut de Cancerologie de la Loire, St-Priest en Jarez (France); Fournel, Pierre [Departement d' Oncologie Medicale, Institut de Cancerologie de la Loire, St-Priest en Jarez (France); Tiffet, Olivier [Service de Chirurgie Thoracique, Centre Hospitalier Universitaire de Saint Etienne, Saint Etienne (France); Schmitt, Thierry [Departement de Radiotherapie, Institut de Cancerologie de la Loire, St-Priest en Jarez (France); and others

2012-07-01

The purpose of this study was to analyze and revisit toxicity related to chest chemoradiotherapy and to correlate these side effects with dosimetric parameters obtained using analytical anisotropic algorithm (AAA) in locally unresectable advanced lung cancer. We retrospectively analyzed data from 47 lung cancer patients between 2005 and 2008. All received conformal 3D radiotherapy using high-energy linear accelerator plus concomitant chemotherapy. All treatment planning data were transferred into Eclipse 8.05 (Varian Medical Systems, Palo Alto, CA) and dosimetric calculations were performed using AAA. Thirty-three patients (70.2%) developed acute pneumopathy after radiotherapy (grades 1 and 2). One patient (2.1%) presented with grade 3 pneumopathy. Thirty-one (66%) presented with grades 1-2 lung fibrosis, and 1 patient presented with grade 3 lung fibrosis. Thirty-four patients (72.3%) developed grade 1-2 acute oesophagic toxicity. Four patients (8.5%) presented with grades 3 and 4 dysphagia, necessitating prolonged parenteral nutrition. Median prescribed dose was 64 Gy (range 50-74) with conventional fractionation (2 Gy per fraction). Dose-volume constraints were respected with a median V20 of 23.5% (maximum 34%) and a median V30 of 17% (maximum 25%). The median dose delivered to healthy contralateral lung was 13.1 Gy (maximum 18.1 Gy). At univariate analysis, larger planning target volume and V20 were significantly associated with the probability of grade {>=}2 radiation-induced pneumopathy (p = 0.022 and p = 0.017, respectively). No relation between oesophagic toxicity and clinical/dosimetric parameters could be established. Using AAA, the present results confirm the predictive value of the V20 for lung toxicity as already demonstrated with the conventional pencil beam convolution approach.

A dosimetric comparison of whole-lung treatment techniques in the pediatric population

International Nuclear Information System (INIS)

Bosarge, Christina L.; Ewing, Marvene M.; DesRosiers, Colleen M.; Buchsbaum, Jeffrey C.

2016-01-01

To demonstrate the dosimetric advantages and disadvantages of standard anteroposterior-posteroanterior (S-AP/PA_A_A_A), inverse-planned AP/PA (IP-AP/PA) and volumetry-modulated arc (VMAT) radiotherapies in the treatment of children undergoing whole-lung irradiation. Each technique was evaluated by means of target coverage and normal tissue sparing, including data regarding low doses. A historical approach with and without tissue heterogeneity corrections is also demonstrated. Computed tomography (CT) scans of 10 children scanned from the neck to the reproductive organs were used. For each scan, 6 plans were created: (1) S-AP/PA_A_A_A using the anisotropic analytical algorithm (AAA), (2) IP-AP/PA, (3) VMAT, (4) S-AP/PA_N_O_N_E without heterogeneity corrections, (5) S-AP/PA_P_B using the Pencil-Beam algorithm and enforcing monitor units from technique 4, and (6) S-AP/PA_A_A_A_[_F_M_] using AAA and forcing fixed monitor units. The first 3 plans compare modern methods and were evaluated based on target coverage and normal tissue sparing. Body maximum and lower body doses (50% and 30%) were also analyzed. Plans 4 to 6 provide a historic view on the progression of heterogeneity algorithms and elucidate what was actually delivered in the past. Averages of each comparison parameter were calculated for all techniques. The S-AP/PA_A_A_A technique resulted in superior target coverage but had the highest maximum dose to every normal tissue structure. The IP-AP/PA technique provided the lowest dose to the esophagus, stomach, and lower body doses. VMAT excelled at body maximum dose and maximum doses to the heart, spine, and spleen, but resulted in the highest dose in the 30% body range. It was, however, superior to the S-AP/PA_A_A_A approach in the 50% range. Each approach has strengths and weaknesses thus associated. Techniques may be selected on a case-by-case basis and by physician preference of target coverage vs normal tissue sparing.

A dosimetric comparison of whole-lung treatment techniques in the pediatric population

Energy Technology Data Exchange (ETDEWEB)

Bosarge, Christina L., E-mail: cbosarge@umail.iu.edu; Ewing, Marvene M.; DesRosiers, Colleen M.; Buchsbaum, Jeffrey C.

2016-07-01

To demonstrate the dosimetric advantages and disadvantages of standard anteroposterior-posteroanterior (S-AP/PA{sub AAA}), inverse-planned AP/PA (IP-AP/PA) and volumetry-modulated arc (VMAT) radiotherapies in the treatment of children undergoing whole-lung irradiation. Each technique was evaluated by means of target coverage and normal tissue sparing, including data regarding low doses. A historical approach with and without tissue heterogeneity corrections is also demonstrated. Computed tomography (CT) scans of 10 children scanned from the neck to the reproductive organs were used. For each scan, 6 plans were created: (1) S-AP/PA{sub AAA} using the anisotropic analytical algorithm (AAA), (2) IP-AP/PA, (3) VMAT, (4) S-AP/PA{sub NONE} without heterogeneity corrections, (5) S-AP/PA{sub PB} using the Pencil-Beam algorithm and enforcing monitor units from technique 4, and (6) S-AP/PA{sub AAA[FM]} using AAA and forcing fixed monitor units. The first 3 plans compare modern methods and were evaluated based on target coverage and normal tissue sparing. Body maximum and lower body doses (50% and 30%) were also analyzed. Plans 4 to 6 provide a historic view on the progression of heterogeneity algorithms and elucidate what was actually delivered in the past. Averages of each comparison parameter were calculated for all techniques. The S-AP/PA{sub AAA} technique resulted in superior target coverage but had the highest maximum dose to every normal tissue structure. The IP-AP/PA technique provided the lowest dose to the esophagus, stomach, and lower body doses. VMAT excelled at body maximum dose and maximum doses to the heart, spine, and spleen, but resulted in the highest dose in the 30% body range. It was, however, superior to the S-AP/PA{sub AAA} approach in the 50% range. Each approach has strengths and weaknesses thus associated. Techniques may be selected on a case-by-case basis and by physician preference of target coverage vs normal tissue sparing.

Intraoperative real-time planned conformal prostate brachytherapy: Post-implantation dosimetric outcome and clinical implications

International Nuclear Information System (INIS)

Zelefsky, Michael J.; Yamada, Yoshiya; Cohen, Gil'ad N.; Sharma, Neha; Shippy, Alison M.; Fridman, David; Zaider, Marco

2007-01-01

Purpose: To report the dosimetric outcome of patients with clinically localized prostate cancer treated with I-125 permanent implantation using an intraoperative real-time conformal planning technique. Methods and materials: Five hundred and sixty-two patients with prostate cancer were treated with I-125 permanent interstitial implantation using a transrectal ultrasound-guided approach. Real-time intraoperative treatment planning software that incorporates inverse planning optimization was used. Dose-volume constraints for this inverse-planning system included: prostate V100 ≥95%, maximal urethral dose ≤120%, and average rectal dose 3 of the rectum was exposed to the prescription dose, the incidence of late grade 2 toxicity rectal toxicity was 9% compared to 4% for smaller volumes of the rectum exposed to similar doses (p = 0.003). No dosimetric parameter in these patients with tight dose confines for the urethra influenced acute or late urinary toxicity. Conclusion: Real-time intraoperative planning was associated with a 90% consistency of achieving the planned intraoperative dose constraints for target coverage and maintaining planned urethral and rectal constraints in a high percentage of implants. Rectal volumes of ≥2.5 cm 3 exposed to the prescription doses were associated with an increased incidence of grade 2 rectal bleeding. Further enhancements in imaging guidance for optimal seed deposition are needed to guarantee optimal dose distribution for all patients. Whether such improvements lead to further reduction in acute and late morbidities associated with therapy requires further study

Dosimetric approaches: pregnancy and lactation

International Nuclear Information System (INIS)

Rojo, Ana M.

2001-01-01

The female nuclear medicine patient is of special concern to the evaluation of radiation dose since radiation protection point of view: a)- The females overall body size and organ sizes are generally smaller than those of her male counterpart (thus her radiation doses will be higher, given the same amounts of administered activity and similar biokinetics), the effective doses could be 25 per cent higher than a man; b)- Female gonads are inside the body instead of outside and are near several organs often important as source organs in internal dosimetry; female gonads doses could be up to 10 or 30 higher than male gonads (usually 3 order); c)- Risk of breast cancer is significantly higher among females than males; d)- During the pregnancy due to placental transfer of radiopharmaceuticals or radiation exposure from the urinary bladder the embryo/fetus could receive doses that must be avoid; e)- In the case of nursing infant is of special concern in such an analysis to determine the interruption period to avoid doses in the nursing infant. The dosimetric approaches to take account to assess internal doses in the pregnant woman and during the breast feeding are discussed. (author)

Dosimetric effects of an air cavity for the SAVI partial breast irradiation applicator

Energy Technology Data Exchange (ETDEWEB)

Richardson, Susan L.; Pino, Ramiro [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110 (United States); Department of Radiation Oncology, Methodist Hospital, Houston, Texas 77030 and Texas Cancer Clinic, San Antonio, Texas 78240 (United States)

2010-08-15

Purpose: To investigate the dosimetric effect of the air inside the SAVI partial breast irradiation device. Methods: The authors have investigated how the air inside the SAVI partial breast irradiation device changes the delivered dose from the homogeneously calculated dose. Measurements were made with the device filled with air and water to allow comparison to a homogenous dose calculation done by the treatment planning system. Measurements were made with an ion chamber, TLDs, and film. Monte Carlo (MC) simulations of the experiment were done using the EGSnrc suite. The MC model was validated by comparing the water-filled calculations to those from a commercial treatment planning system. Results: The magnitude of the dosimetric effect depends on the size of the cavity, the arrangement of sources, and the relative dwell times. For a simple case using only the central catheter of the largest device, MC results indicate that the dose at the prescription point 1 cm away from the air-water boundary is about 9% higher than the homogeneous calculation. Independent measurements in a water phantom with a similar air cavity gave comparable results. MC simulation of a realistic multidwell position plan showed discrepancies of about 5% on average at the prescription point for the largest device. Conclusions: The dosimetric effect of the air cavity is in the range of 3%-9%. Unless a heterogeneous dose calculation algorithm is used, users should be aware of the possibility of small treatment planning dose errors for this device and make modifications to the treatment delivery, if necessary.

Initial Report of a Prospective Dosimetric and Clinical Feasibility Trial Demonstrates the Potential of Protons to Increase the Therapeutic Ratio in Breast Cancer Compared With Photons

Energy Technology Data Exchange (ETDEWEB)

Bradley, Julie A., E-mail: jbradley@floridaproton.org; Dagan, Roi; Ho, Meng Wei; Rutenberg, Michael; Morris, Christopher G.; Li, Zuofeng; Mendenhall, Nancy P.

2016-05-01

Purpose: To compare dosimetric endpoints between proton therapy (PT) and conventional radiation and determine the feasibility of PT for regional nodal irradiation (RNI) in women with breast cancer. Methods and Materials: From 2012 to 2014, 18 women (stage IIA-IIIB) requiring RNI prospectively enrolled on a pilot study. Median age was 51.8 years (range, 42-73 years). The cohort included breast-conserving therapy (BCT) and mastectomy patients and right- and left-sided cancers. Treatment targets and organs at risk were delineated on computed tomography scans, and PT and conventional plans were developed. Toxicity was prospectively recorded using Common Terminology Criteria for Adverse Events version 4.0. A Wilcoxon signed-rank sum test compared the dose-volume parameters. The primary endpoint was a reduction in cardiac V5. Results: Median follow-up was 20 months (range, 2-31 months). For all patients, the PT plan better met the dosimetric goals and was used for treatment. Proton therapy alone was used for 10 patients (9 postmastectomy, 1 after BCT) and combined proton–photon in 8 (6 BCT, 2 postmastectomy with immediate expander reconstruction). Proton therapy improved coverage of level 2 axilla (P=.0005). Adequate coverage of internal mammary nodes was consistently achieved with PT (median D95, 50.3 Gy; range, 46.6-52.1 Gy) but not with conventional radiation therapy (median D95, 48.2 Gy; range, 40.8-55 Gy; P=.0005). Median cardiac V5 was 0.6% with PT and 16.3% with conventional radiation (P<.0001). Median ipsilateral lung V5 and V20 were improved with PT (median V5 35.3% vs 60.5% [P<.0001]; and median V20, 21.6% vs 35.5% [P<.0001]). Grade 3 dermatitis developed in 4 patients (22%), which was the only grade 3 toxicity. No grade 4+ toxicities developed. Conclusion: Proton therapy for RNI after mastectomy or BCT significantly improves cardiac dose, especially for left-sided patients, and lung V5 and V20 in all patients without excessive acute toxicity

SU-F-T-189: Dosimetric Comparison of Spot-Scanning Proton Therapy Techniques for Liver Tumors Close to the Skin Surface

International Nuclear Information System (INIS)

Takao, S; Matsuzaki, Y; Matsuura, T; Umegaki, K; Fujii, Y; Fujii, T; Katoh, N; Shimizu, S; Shirato, H

2016-01-01

Purpose: Spot-scanning technique has been utilized to achieve conformal dose distribution to large and complicated tumors. This technique generally does not require patient-specific devices such as aperture and compensator. The commercially available spot-scanning proton therapy (SSPT) systems, however, cannot deliver proton beams to the region shallower than 4 g/cm2. Therefore some range compensation device is required to treat superficial tumors with SSPT. This study shows dosimetric comparison of the following treatment techniques: (i) with a tabletop bolus, (ii) with a nozzle-mounted applicator, and (iii) without any devices and using intensity-modulated proton therapy (IMPT) technique. Methods: The applicator composed of a combination of a mini-ridge filter and a range shifter has been manufactured by Hitachi, Ltd., and the tabletop bolus was made by .decimal, Inc. Both devices have been clinically implemented in our facility. Three patients with liver tumors close to the skin surface were examined in this study. Each treatment plan was optimized so that the prescription dose of 76 Gy(RBE) or 66 Gy(RBE) would be delivered to 99% of the clinical target volume in 20 fractions. Three beams were used for tabletop bolus plan and IMPT plan, whereas two beams were used in the applicator plan because the gantry angle available was limited due to potential collision to patient and couch. The normal liver, colon, and skin were considered as organs at risk (OARs). Results: The target heterogeneity index (HI = D_5/D_9_5) was 1.03 on average in each planning technique. The mean dose to the normal liver was considerably less than 20 Gy(RBE) in all cases. The dose to the skin could be reduced by 20 Gy(RBE) on average in the IMPT plan compared to the applicator plan. Conclusion: It has been confirmed that all treatment techniques met the dosimetric criteria for the OARs and could be implemented clinically.

SU-F-T-189: Dosimetric Comparison of Spot-Scanning Proton Therapy Techniques for Liver Tumors Close to the Skin Surface

Energy Technology Data Exchange (ETDEWEB)

Takao, S; Matsuzaki, Y [Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Hokkaido (Japan); Matsuura, T; Umegaki, K [Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido (Japan); Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido (Japan); Fujii, Y; Fujii, T [Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido (Japan); Katoh, N [Department of Radiation Oncology, Hokkaido University Hospital, Sapporo, Hokkaido (Japan); Shimizu, S; Shirato, H [Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido (Japan); Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido (Japan)

2016-06-15

Purpose: Spot-scanning technique has been utilized to achieve conformal dose distribution to large and complicated tumors. This technique generally does not require patient-specific devices such as aperture and compensator. The commercially available spot-scanning proton therapy (SSPT) systems, however, cannot deliver proton beams to the region shallower than 4 g/cm2. Therefore some range compensation device is required to treat superficial tumors with SSPT. This study shows dosimetric comparison of the following treatment techniques: (i) with a tabletop bolus, (ii) with a nozzle-mounted applicator, and (iii) without any devices and using intensity-modulated proton therapy (IMPT) technique. Methods: The applicator composed of a combination of a mini-ridge filter and a range shifter has been manufactured by Hitachi, Ltd., and the tabletop bolus was made by .decimal, Inc. Both devices have been clinically implemented in our facility. Three patients with liver tumors close to the skin surface were examined in this study. Each treatment plan was optimized so that the prescription dose of 76 Gy(RBE) or 66 Gy(RBE) would be delivered to 99% of the clinical target volume in 20 fractions. Three beams were used for tabletop bolus plan and IMPT plan, whereas two beams were used in the applicator plan because the gantry angle available was limited due to potential collision to patient and couch. The normal liver, colon, and skin were considered as organs at risk (OARs). Results: The target heterogeneity index (HI = D{sub 5}/D{sub 95}) was 1.03 on average in each planning technique. The mean dose to the normal liver was considerably less than 20 Gy(RBE) in all cases. The dose to the skin could be reduced by 20 Gy(RBE) on average in the IMPT plan compared to the applicator plan. Conclusion: It has been confirmed that all treatment techniques met the dosimetric criteria for the OARs and could be implemented clinically.

Radiochromic film in the dosimetric verification of intensity modulated radiation therapy

International Nuclear Information System (INIS)

Zhou Yingjuan; Huang Shaomin; Deng Xiaowu

2007-01-01

Objective: Objective To investigate the dose-response behavior of a new type of radio- chromic film( GAFCHROMIC EBT) and explore the clinical application means and precision of dosage measurement, which can be applied for: (1) plan-specific dosimetric verification for intensity modulated radiation therapy, (2) to simplify the process of quality assurance using traditional radiographic film dosimetric system and (3) to establish a more reliable, more efficient dosimetric verification system for intensity modulated radiation therapy. Methods: (1) The step wedge calibration technique was used to calibrate EBT radiochromic film and EDR2 radiographic film. The dose characteristics, the measurement consistency and the quality assurance process between the two methods were compared. (2) The in-phantom dose-measurement based verification technique has been adopted. Respectively, EBT film and EDR2 film were used to measure the same dose plane of IMRT treatment plans. The results of the dose map, dose profiles and iso- dose curves were compared with those calculated by CORVUS treatment planning system to evaluate the function of EBT film for dosimetric verification for intensity modulated radiation therapy. Results: (1) Over the external beam dosimetric range of 0-500 cGy, EBT/VXR-16 and EDR2/VXR-16 film dosimetric system had the same measurement consistency with the measurement variability less then 0.70%. The mean measurement variability of these two systems was 0.37% and 0.68%, respectively. The former proved to be the superior modality at measurement consistency, reliability, and efficiency over dynamic clinical dose range , furthermore, its quality assurance showed less process than the latter. (2) The dosimetric verification of IMRT plane measured with EBT film was quite similar to that with EDR2 film which was processed under strict quality control. In a plane of the phantom, the maximal dose deviation off axis between EBT film measurement and the TPS calculation was

Radiation and chemoradiation treatment of esophagus cancer

International Nuclear Information System (INIS)

Azhigaliev, N.; Kusherbaev, S.; Abdrakhmanov, Zh.

1988-01-01

Indications and contraindications for radiation treatment of esophagus cancer are presented. The role of chemoradiation among esophagus cancer treatment methods is determined.Thechnical, dosimetric and clinical data are sequently delivered. Preparation of a patient for chemoradiation is described. Recommendations on their most efficient use are given

DARTAB: a program to combine airborne radionuclide environmental exposure data with dosimetric and health effects data to generate tabulations of predicted health impacts

International Nuclear Information System (INIS)

Begovich, C.L.; Eckerman, K.F.; Schlatter, E.C.; Ohr, S.Y.; Chester, R.O.

1981-08-01

The DARTAB computer code combines radionuclide environmental exposure data with dosimetric and health effects data to generate tabulations of the predicted impact of radioactive airborne effluents. DARTAB is independent of the environmental transport code used to generate the environmental exposure data and the codes used to produce the dosimetric and health effects data. Therefore human dose and risk calculations need not be added to every environmental transport code. Options are included in DARTAB to permit the user to request tabulations by various topics (e.g., cancer site, exposure pathway, etc.) to facilitate characterization of the human health impacts of the effluents. The DARTAB code was written at ORNL for the US Environmental Protection Agency, Office of Radiation Programs

Dosimetric quality control of treatment planning systems in external radiation therapy using Digital Test Objects calculated by PENELOPE Monte-Carlo simulations

International Nuclear Information System (INIS)

Ben Hdech, Yassine

2011-01-01

To ensure the required accuracy and prevent from mis-administration, cancer treatments, by external radiation therapy are simulated on Treatment Planning System or TPS before radiation delivery in order to ensure that the prescription is achieved both in terms of target volumes coverage and healthy tissues protection. The TPS calculates the patient dose distribution and the treatment time per beam required to deliver the prescribed dose. TPS is a key system in the decision process of treatment by radiation therapy. It is therefore essential that the TPS be subject to a thorough check of its performance (quality control or QC) and in particular its ability to accurately compute dose distributions for patients in all clinical situations that be met. The 'traditional' methods recommended to carry out dosimetric CQ of algorithms implemented in the TPS are based on comparisons between dose distributions calculated with the TPS and dose measured in physical test objects (PTO) using the treatment machine. In this thesis we propose to substitute the reference dosimetric measurements performed in OTP by benchmark dose calculations in Digital Test Objects using PENELOPE Monte-Carlo code. This method has three advantages: (i) it allows simulation in situations close to the clinic and often too complex to be experimentally feasible; (ii) due to the digital form of reference data the QC process may be automated; (iii) it allows a comprehensive TPS CQ without hindering the use of an equipment devoted primarily to patients treatments. This new method of CQ has been tested successfully on the Eclipse TPS from Varian Medical Systems Company. (author) [fr

Dosimetric and clinical experience in eye proton treatment at INFN-LNS

International Nuclear Information System (INIS)

Cirrone, G. A. P.; Cuttone, G.; Di Rosa, F.; Lojacono, P.; Mongelli, V.; Patti, I. V.; Pittera, S.; Russo, G.; Valastro, L. M.; Lo Nigro, S.; Ott, J.; Reibaldi, A.; Privitera, G.; Raffaele, L.; Salamone, V.; Spatola, C.; Sabini, M. G.

2009-01-01

After six years of activity 155 patients have been treated inside the CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) facility. CATANA is the first and unique proton therapy facility in which the 62 MeV proton beams, accelerated by a Superconducting Cyclotron, are used for the radio-therapeutic treatments of choroidal and iris melanomas. Inside CATANA new absolute and relative dosimetric techniques have been developed in order to achieve the best results in terms of treatment precision and dose release accuracy. The follow-up results for 42 patients demonstrated the efficacy of high energy protons in the radiotherapeutic field and encouraged us in our activity in the battle against cancer

Dosimetric and clinical experience in eye proton treatment at INFN-LNS

Science.gov (United States)

Cirrone, G. A. P.; Cuttone, G.; Di Rosa, F.; Lojacono, P.; Mongelli, V.; Lo Nigro, S.; Ott, J.; Patti, I. V.; Pittera, S.; Privitera, G.; Raffaele, L.; Reibaldi, A.; Russo, G.; Salamone, V.; Sabini, M. G.; Spatola, C.; Valastro, L. M.

2009-05-01

After six years of activity 155 patients have been treated inside the CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) facility. CATANA is the first and unique proton therapy facility in which the 62 MeV proton beams, accelerated by a Superconducting Cyclotron, are used for the radio-therapeutic treatments of choroidal and iris melanomas. Inside CATANA new absolute and relative dosimetric techniques have been developed in order to achieve the best results in terms of treatment precision and dose release accuracy. The follow-up results for 42 patients demonstrated the efficacy of high energy protons in the radiotherapeutic field and encouraged us in our activity in the battle against cancer

If psychosis were cancer: a speculative comparison

Science.gov (United States)

Boden, Zoë; Newton, Elizabeth

2017-01-01

Recently, health policy in the UK has begun to engage with the concept of ‘parity of esteem’ between physical and mental healthcare. This has led one recent initiative to improve service provision for first episode psychosis, which aims to bring it into line with some of the principles underpinning good practice in cancer care. In this paper, we consider some of the metaphorical consequences of likening psychosis to cancer. While we find the comparison unhelpful for clinical purposes, we argue that it can be a helpful lens through which to examine service provision for psychosis in young people. Through this lens, specialist community-based services would appear to compare reasonably well. Inpatient care for young people with psychosis, on the other hand, suffers very badly by comparison with inpatient facilities for teenage cancer care. We note some of the many positive features of inpatient cancer care for young adults, and—drawing upon previous research on inpatient psychiatric care—observe that many of these are usually absent from mental health facilities. We conclude that this metaphor may be a helpful rhetorical device for communicating the lack of ‘parity of esteem’ between mental and physical healthcare. This inequity must be made visible in health policy, in commissioning, and in service provision. PMID:28559369

Discussion on concepts for radiological dosimetric quantities in the Japan Health Physics Society

International Nuclear Information System (INIS)

Takahashi, Fumiaki; Oda, Keiji

2007-01-01

Many dosimetric quantities have been used for radiation protection purpose. The International Commission on Radiological Protection (ICRP) has recommended protection quantities and the International Commission on Radiation Units and Measurements (ICRU) has introduced operational quantities to provide a reasonable estimate of the protection quantities. Enthusiastic discussions are continuously made on the issues of the dosimetric quantities, such as basic biological data for the definition of these quantities and applicability of the quantities to actual radiation protection practice. At the moment, some changes are being proposed concerning dosimetric quantities in the draft recommendations of ICRP, opened for consultation in recent years. Thus, the Japan Health Physics Society (JHPS) established the Expert Committee on concepts of Dosimetric Quantities used in radiological protection (ECDQ) in April 2005 to reviewed and discuss issues in the dosimetric quantities. (author)

Design and development of spine phantom to verify dosimetric accuracy of stereotactic body radiation therapy using 3D prnter

Energy Technology Data Exchange (ETDEWEB)

Lee, Seu Ran; Lee, Min Young; Kim, Min Joo; Park, So Hyun; Song Ji Hye; Suh, Tae Suk [Dept. of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of); Sohn, Jason W. [Dept. of Radiation Oncology, College of Medicine, Case Western Reserve University, Cleveland (United States)

2015-10-15

The purpose of this study is to verify dosimetric accuracy of delivered dose in spine SBRT as highly precise radiotherapy depending on cancer position using dedicated spine phantom based on 3D printer. Radiation therapy oncology group (RTOG) 0631 suggest different planning method in spine stereotactic body radiation therapy (SBRT) according to location of cancer owing to its distinct shape. The developed phantom especially using DLP method can be utilized as spine SBRT dosimetry research. Our study was able to confirm that the phantom was indeed similar with HU value of human spine as well as its shape.

Post-pneumonectomy empyema and dosimetric CT scan. Report of two cases and review of literature

International Nuclear Information System (INIS)

Latorzeff, I.; Bachaud, J.M.; Aziza, R.; Arboucalot, F.; Berjaud, J.; Dahan, M.; Giron, J.

1999-01-01

Following a pneumonectomy for cancer, the patients are classically observed by clinical examination and standard chest X-ray. However, torpid empyemas can be missed when they occur after the period of hospitalization and when they are not accompanied by a fever, At the time of postoperative radiotherapy, the dosimetric CT scan constitutes the first examination providing objective information of the endo-thoracic content. It is therefore necessary on this occasion to assure the normality of the post-pneumonectomy pleural space while checking that the substituted liquid is homogeneous and above all that the internal mediastinal part of the cavity has a concave appearance. If that is not the case, an empyema should be suspected. The diagnosis, confirmed by a cyto-bacteriological examination of the pleural fluid, constitutes a counter-indication of the radiotherapy. We present two cases of post-pneumonectomy pauci-symptomatic empyema which were diagnosed during the course of postoperative radiotherapy when the initial dosimetric CT scan was pathologic and could have allowed an earlier diagnosis. (author)

Dosimetric Comparison of Three Dimensional Conformal Radiation Radiotherapy and Helical Tomotherapy Partial Breast Cancer

International Nuclear Information System (INIS)

Kim, Dae Woong; Kim, Jong Won; Choi, Yun Kyeong; Kim, Jung Soo; Hwang, Jae Woong; Jeong, Kyeong Sik; Choi, Gye Suk

2008-01-01

The goal of radiation treatment is to deliver a prescribed radiation dose to the target volume accurately while minimizing dose to normal tissues. In this paper, we comparing the dose distribution between three dimensional conformal radiation radiotherapy (3D-CRT) and helical tomotherapy (TOMO) plan for partial breast cancer. Twenty patients were included in the study, and plans for two techniques were developed for each patient (left breast:10 patients, right breast:10 patients). For each patient 3D-CRT planning was using pinnacle planning system, inverse plan was made using Tomotherapy Hi-Art system and using the same targets and optimization goals. We comparing the Homogeneity index (HI), Conformity index (CI) and sparing of the organs at risk for dose-volume histogram. Whereas the HI, CI of TOMO was significantly better than the other, 3D-CRT was observed to have significantly poorer HI, CI. The percentage ipsilateral non-PTV breast volume that was delivered 50% of the prescribed dose was 3D-CRT (mean: 40.4%), TOMO (mean: 18.3%). The average ipsilateral lung volume percentage receiving 20% of the PD was 3D-CRT (mean: 4.8%), TOMO (mean: 14.2), concerning the average heart volume receiving 20% and 10% of the PD during treatment of left breast cancer 3D-CRT (mean: 1.6%, 3.0%), TOMO (mean: 9.7%, 26.3%) In summary, 3D-CRT and TOMO techniques were found to have acceptable PTV coverage in our study. However, in TOMO, high conformity to the PTV and effective breast tissue sparing was achieved at the expense of considerable dose exposure to the lung and heart.

Dosimetric study of the total corporal irradiation with high energy photons: Comparison between a linac mevatron KD and a bomb of 60CO Rokus M-132

International Nuclear Information System (INIS)

Bernal, M. A.; Silvestre, I

2001-01-01

Several dosimetric aspects of a 6 0 Co beam and another of 15 MV R X, of a linear accelerator, used for the Whole-Body Irradiation (WBI), as part of the bone marrow transplants, are studied. The lineal accelerator offers better beam characteristics. The dosimetric field is bigger and offers smaller dimness, which facilitates a higher dose homogeneity along the patient [es

Study of a new dosimetric radio-thermoluminescent systems

International Nuclear Information System (INIS)

Cazac, T.C.

1980-01-01

This is the first Romanian study to investigate conditions to obtain the radio-thermo-luminescent systems: MgB 4 O 7 :A(A-Nd,Sm,Eu,Dy,Tb,Dy+Sm and Tb+Sm) MgF 2 A (A=Mn,Dy,Tb,Sm,Li), their essential dosimetric characters, as well as the (MgF 2 =Mn) thermophosphorus mixture with a ( 6 LiF) lithium target. An investigation was developed upon a new category of radio-thermoluminescent detectors with low radiation energy dependence and fading, magnesjum boride activated by several elements of the lanthanides class (Nd,Sm,Eu,Dy,Tb). A new radio-thermoluminescent dosimetric system with high sensitivity and moderate dependence on energy radiation - (Mnsup(2+)) manganese activated magnesium fluoride - was also studied. The author explored application of investigated detectors MgF 2 =Mn, MgB 4 O 7 =Dy and MgB 4 O 7 :Tb in neutron dosimetry in complex gamma-neutron fields. It is deemed that by using the dosimetric systems reported in the thesis in order to measure gamma, beta and neutron radiation doses, dosimetric control can be ensured both in professional dosimetry and in nuclear accident dosimetry, as well as in various basic and applicative investigations. A modest contribution is thus made towards achieving the national nuclear program through an extension of the thermophosphorus range with practical applications in nuclear radiation dosimetry. (author)

Follow-up effects of social comparison information on the quality of life of cancer patients: The moderating role of social comparison orientation

NARCIS (Netherlands)

Buunk, A.P.; Bennenbroek, F.T.C.; Stiegelis, H.E.; Bergh, A.C.M. van den; Sanderman, R.; Hagedoorn, M.

2012-01-01

Objective: To examine how social comparison orientation (SCO) moderates the effects of three types of social comparison information on the global quality of life of cancer patients 2 weeks and 3 months later. Design: Cancer patients (n = 226) were provided with social comparison information just

Dosimetric methodology for extremities of individuals occupationally exposed to beta radiation using the optically stimulated luminescence technique

International Nuclear Information System (INIS)

Pinto, Teresa Cristina Nathan Outeiro

2010-01-01

A dosimetric methodology was established for the determination of extremity doses of individuals occupationally exposed to beta radiation, using Al 2 O 3 :C detectors and the optically stimulated luminescence (OSL) reader system microStar, Landauer. The main parts of the work were: characterization of the dosimetric material Al 2 O 3 :C using the OSL technique; establishment of the dose evaluation methodology; dose rate determination of beta radiation sources; application of the established method in a practical test with individuals occupationally exposed to beta radiation during a calibration simulation of clinical applicators; validation of the methodology by the comparison between the dose results of the practical test using the OSL and the thermoluminescence (TL) techniques. The results show that both the OSL Al-2O 3 :C detectors and the technique may be utilized for individual monitoring of extremities and beta radiation. (author)

Dosimetric study of optimal beam number and arrangement for treatment of nasopharyngeal carcinoma with intensity-modulated radiation therapy

International Nuclear Information System (INIS)

Budrukkar, Ashwini; Corry, June; Peters, Lester J.; Hope, Geoff; Cramb, Jim

2004-01-01

The purpose of this dosimetric study was to evaluate the effect of beam number and arrangement on the dose distribution with intensity-modulated radiation therapy in patients with nasopharyngeal cancer. Computed tomography data sets of seven patients who were treated for nasopharyngeal carcinoma at the Peter MacCallum Cancer Centre were used for the present dosimetric study. The dose planned was 70 Gy in 7 weeks for the gross nasopharyngeal and nodal disease and the biological equivalents of 60 Gy in 6 weeks for the high-risk and 50 Gy in 5 weeks for the low-risk nodal disease. A plan using seven fields was compared to that using nine fields in all patients. Plans were assessed on the dose to the planning target volume (PTV) and the degree of parotid sparing achieved by evaluating both dose-volume histograms (DVH) and axial slices. Seven fields (three anterior and four posterior) provide good PTV coverage and satisfactory parotid sparing in patients with localized nasopharyngeal lesions. Nine fields appear to be better for tumours with significant posterolateral parapharyngeal extension. Parotid sparing is consistently better with nine fields. Both DVH and axial slices need to be evaluated before accepting any plan Copyright (2004) Blackwell Publishing Asia Pty Ltd

Dosimetric effects of edema in permanent prostate seed implants: a rigorous solution

International Nuclear Information System (INIS)

Chen Zhe; Yue Ning; Wang Xiaohong; Roberts, Kenneth B.; Peschel, Richard; Nath, Ravinder

2000-01-01

Purpose: To derive a rigorous analytic solution to the dosimetric effects of prostate edema so that its impact on the conventional pre-implant and post-implant dosimetry can be studied for any given radioactive isotope and edema characteristics. Methods and Materials: The edema characteristics observed by Waterman et al (Int. J. Rad. Onc. Biol. Phys, 41:1069-1077; 1998) was used to model the time evolution of the prostate and the seed locations. The total dose to any part of prostate tissue from a seed implant was calculated analytically by parameterizing the dose fall-off from a radioactive seed as a single inverse power function of distance, with proper account of the edema-induced time evolution. The dosimetric impact of prostate edema was determined by comparing the dose calculated with full consideration of prostate edema to that calculated with the conventional dosimetry approach where the seed locations and the target volume are assumed to be stationary. Results: A rigorous analytic solution on the relative dosimetric effects of prostate edema was obtained. This solution proved explicitly that the relative dosimetric effects of edema, as found in the previous numerical studies by Yue et. al. (Int. J. Radiat. Oncol. Biol. Phys. 43, 447-454, 1999), are independent of the size and the shape of the implant target volume and are independent of the number and the locations of the seeds implanted. It also showed that the magnitude of relative dosimetric effects is independent of the location of dose evaluation point within the edematous target volume. It implies that the relative dosimetric effects of prostate edema are universal with respect to a given isotope and edema characteristic. A set of master tables for the relative dosimetric effects of edema were obtained for a wide range of edema characteristics for both 125 I and 103 Pd prostate seed implants. Conclusions: A rigorous analytic solution of the relative dosimetric effects of prostate edema has been

Quality control of dosimetric systems using thermoluminescent crystals; Control de calidad de un sistema de planeacion dosimetrico utilizando cristales termoluminiscentes y su aplicacion en tratamientos de pacientes con cancer de prostata

Energy Technology Data Exchange (ETDEWEB)

Mahecha, L.; Plazas, M. C.; Machado, M.; Perea, M. D.

2006-07-01

To achieve an optimal tumoral control to prostate cancer in early and locally advanced stages, it is necessary to increase the dose with a low mobility probability at the vesicle an rectal level. This is achieved through conformal radiotherapy. The Instituto Nacional de Cancerologia uses this technique, but two questions arise from the medical-physicists and medical radio-oncologist: In accordance with clinical protocols, the conformal radiotherapy delivers a low dose to the adjacent healthy tissues. What experimental method exists that can prove with certainly the veracity of this affirmation?. And, Do the dosimetric simulation system calculate suitable the dose for each tissues?. Through thermoluminescent dosimetry and the use of a physical simulator,we measured the absorbed dose at the target volume and the adjacent tissues using conformal and conventional radiotherapy. We proved that organs such as the rectum and bladder, receiver a minor dose in conformal radiotherapy, hence reducing their mobility probability. In addition, the readings from the thermoluminescent dosimeters and the doses calculated by the ECLIPSE dosimetric system were compared, concluding that the patient's prescribed dose is effectively delivered as recommended by the quality control program in radiotherapy. (Author)

SU-E-T-210: Comparison of Proton with Electron Boost in Breast Cancer Treatment

Energy Technology Data Exchange (ETDEWEB)

Zheng, Y; Chang, A [Procure Proton Therapy Center, Oklahoma City, OK (United States); Liu, Y [INTEGRIS Cancer Institute of Oklahoma, Oklahoma City, OK (United States)

2015-06-15

Purpose: Electron beams are commonly used for boost radiation following whole breast irradiation (WBI) to improve the in-breast local control. Proton beams have a finite range and a sharper distal dose falloff compared to electron beams, thus potentially sparing more heart and lung in breast treatment. The purpose of the study is to compare protons with electrons for boost breast treatment in terms of target coverage and normal tissue sparing. Methods: Six breast cancer patients were included in this study. All women received WBI to 45–50 Gy, followed by a 10–16.2 Gy boost with standard fractionation. If proton beams were used for the boost treatment, an electron plan was retrospectively generated for comparison using the same CT set and structures, and vice versa if electron beams were used for treatment. Proton plans were generated using the treatment planning system (TPS) with two to three uniform scanning proton beams. Electron plans were generated using the Pinnacle TPS with one single en face beam. Dose-volume histograms (DVH) were calculated and compared between proton and electron boost plans. Results: Proton plans show a similar boost target coverage, similar skin dose, and much better heart and lung sparing. For an example patient, V95% for PTV was 99.98% and skin (5 mm shell) received a max dose close to the prescription dose for both protons and electrons; however, V2 and V5 for the ipsilateral lung and heart were 37.5%, 17.9% and 19.9%, 4.9% respectively for electrons, but were essentially 0 for protons. Conclusions: This dosimetric comparison demonstrates that while both proton therapy and electron therapy provided similar coverage and skin dose, proton therapy could largely reduce the dose to lung and heart, thus leading to potential less side effects.

Dosimetric evaluation program for dental radiology practices

International Nuclear Information System (INIS)

Gregori, B.; Milat, J.; Fernandez, J.; Micinquevich, S.; Andrieu, J.

1992-01-01

The preliminary results of a program undertaken to estimate the doses to patients associated with dental radiology practices in Argentine, are presented. Information collected from the search demonstrated that the Dieck and coronal techniques are the most commonly used practices, while all the examinations are performed by using a circular collimator. For both practices, the dosimetric studies were carried out on a Rando Alderson phantom. All dose measurements were made using thermoluminescent detectors LiF and Ca 2 F. In addition, a mathematical model was developed by applying the Monte Carlo method to a MIRD-V phantom. Circular and rectangular collimators were used. Absorbed dose distribution on head and neck, as well as surface dose distribution, were estimated. The comparison of the performance of both collimators shows that the use of the rectangular one allows for a dose reduction of 80%. Besides, a good correlation between the physical and mathematical models applied was found. (author)

Follow-up effects of social comparison information on the quality of life of cancer patients : The moderating role of social comparison orientation

NARCIS (Netherlands)

Buunk, Abraham P.; Bennenbroek, Femke T. C.; Stiegelis, Heidi E.; van den Bergh, Alfons C. M.; Sanderman, Robbert; Hagedoorn, Mariet

2012-01-01

Objective: To examine how social comparison orientation (SCO) moderates the effects of three types of social comparison information on the global quality of life of cancer patients 2 weeks and 3 months later. Design: Cancer patients (n=226) were provided with social comparison information just prior

EPR dosimetric properties of nano-barium sulfate

International Nuclear Information System (INIS)

Aboelezz, E.; Hassan, G.M.; Sharaf, M.A.; El-Khodary, A.

2015-01-01

Nano/micro BaSO 4 were prepared through the co-precipitation method to measure ionizing radiation doses using electron paramagnetic resonance (EPR). The nano-BaSO 4 sample was characterized using X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. The dose response and fading properties of nano- and micro-phase BaSO 4 were compared in EPR spectra. The prepared nano- and micro-BaSO 4 samples have the same hole and electron centers, which may be attributed to SO 4 − and SO 3 − , respectively. The dosimetric signals for prepared nano- and micro-BaSO 4 have spectroscopic splitting factor (g) with values 2.0025±0.0006 and 2.0027±0.0006, respectively. The nanocrystalline sample has a linear γ-ray dose response over the range 0.4 Gy–1 kGy. The performance parameters which including detection limit and critical level calculated from weighted and unweighted least-squares fitting. The sensitivity of nano-BaSO 4 to γ-ray is one and a half times more than alanine. The lifetime and activation energy for nano-BaSO 4 were estimated by conducting a thermal stability study, and were 5.7±1.1×10 4 years and 0.73±0.14 eV, respectively. The combined and expanded uncertainties accompanying measurements were ±3.89% and ±7.78%, respectively. - Highlights: • Preparation of nano-BaSO 4 using the co-precipitation method. • Study of the dosimetric properties of nano-barium sulfate using the EPR technique. • Comparison between a new EPR dosimeter using nano-materials and standard alanine. • Calculation of the uncertainty budget for nano-BaSO 4

Gamma dosimetric parameters in some skeletal muscle relaxants

Science.gov (United States)

Manjunatha, H. C.

2017-09-01

We have studied the attenuation of gamma radiation of energy ranging from 84 keV to 1330 keV (^{170}Tm, ^{22}Na,^{137}Cs, and ^{60}Co) in some commonly used skeletal muscle relaxants such as tubocurarine chloride, gallamine triethiodide, pancuronium bromide, suxamethonium bromide and mephenesin. The mass attenuation coefficient is measured from the attenuation experiment. In the present work, we have also proposed the direct relation between mass attenuation coefficient (μ /ρ ) and mass energy absorption coefficient (μ _{en}/ρ ) based on the nonlinear fitting procedure. The gamma dosimetric parameters such as mass energy absorption coefficient (μ _{en}/ρ ), effective atomic number (Z_{eff}), effective electron density (N_{el}), specific γ-ray constant, air kerma strength and dose rate are evaluated from the measured mass attentuation coefficient. These measured gamma dosimetric parameters are compared with the theoretical values. The measured values agree with the theoretical values. The studied gamma dosimetric values for the relaxants are useful in medical physics and radiation medicine.

Comparison between Japanese and French interstitial brachytherapy for head and neck cancer

International Nuclear Information System (INIS)

Nose, Takayuki; Koizumi, Masahiko; Nishiyama, Kinji; Inoue, Toshihiko

2001-01-01

Interstitial brachytherapy is the optimal radiotherapy modality for head and neck cancer because the highest dose conformity can be achieved, and implanted tubes can move synchronously with the tumor movement. Compared with radical surgery, interstitial brachytherapy can achieve equivalent local control with less morbidity and less functional deficit. In Japan, because of technical limitations, interstitial brachytherapy has been confined to treatment of small tongue cancers. To improve our head and neck cancer treatment, technical limitations should be eliminated and a wider indication for interstitial brachytherapy should be achieved. In France, interstitial brachytherapy has been technically more developed and widely indicated than in Japan. We analyzed the differences between Japanese (Osaka) and French (Lyon and Nancy) techniques, to improve our interstitial brachytherapy. Implant devices and techniques: French applicators (Longcip 1) are more flexible and more suitable for loop techniques of the soft palate, the base of the tongue, and the vallecula, than applicators available in Japan. Various implant techniques are established especially for the oropharynx in France. Mandibular protection: Lead blocks used in France can more effectively shield the mandible than our silicone spacers. We showed the dosimetric results in an experimental treatment setting. Dose specification: The five-mm dose specification method used in Japan can work only for easy cases, such as small oral tongue cancers and mouth floor cancers. For complicated implants, such as for the oropharynx, the CTV-based dose specification method used in France is essential for sufficient irradiation. Indications: The indication for head and neck interstitial brachytherapy in Japan is limited mostly to small oral tongue cancers. The indication in France is wider, including the oral cavity, the oropharynx, and postoperative cases. We can refine our head and neck cancer treatment if we combine French

Radiotherapy of intensity modulated VS conformational in the treatment of carcinoma of the prostate. A dosimetric comparison; Radioterapia de intensidad modulada VS conformacional en el tratamiento de carcinoma de prostata. Una camparacion dosimetrica

Energy Technology Data Exchange (ETDEWEB)

Rodriguez Martin, G.; Garcia Vicente, F.; Zapatero Laborda, A.; Bermudez Luna, R.; Roch Gonzalez, M.; Perez Gonzalez, L.; Torres Escobar, J. J.

2013-07-01

The intensity modulated (IMRT) radiation therapy is a technique of high conformation which, by its nature, has as one of its main directions prostate cancer radiotherapy treatment. The purpose of this work is presents results of the dosimetric indicators collected in our hospital a number of patients of carcinoma of the prostate with standard three-dimensional Conformal technique (3D-CRT) and IMRT. Aims to demonstrate and quantify with a statistical methodology that, establishing an adequate Protocol of IMRT, significant reductions in risk organ doses can be obtained by keeping the same prescription to the white volume. (Author)

Dosimetric and geometric evaluation of a hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

International Nuclear Information System (INIS)

Liu Han; Wu Qiuwen

2011-01-01

For prostate cancer patients, online image-guided (IG) radiotherapy has been widely used in clinic to correct the translational inter-fractional motion at each treatment fraction. For uncertainties that cannot be corrected online, such as rotation and deformation of the target volume, margins are still required to be added to the clinical target volume (CTV) for the treatment planning. Offline adaptive radiotherapy has been implemented to optimize the treatment for each individual patient based on the measurements at early stages of treatment process. It has been shown that offline adaptive radiotherapy can effectively reduce the required margin. Recently a hybrid strategy of offline adaptive replanning and online IG was proposed and the geometric evaluation was performed. It was found that the planning margins can further be reduced by 1-2 mm compared to online IG only strategy. The purpose of this study was to investigate the dosimetric benefits of such a hybrid strategy on the target and organs at risk. A total of 420 repeated helical computed tomography scans from 28 patients were included in the study. Both low-risk patients (LRP, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles, SV) were included in the simulation. Two registration methods, based on center-of-mass shift of prostate only and prostate plus SV, were performed for IRP. The intensity-modulated radiotherapy was used in the simulation. Criteria on both cumulative and fractional doses were evaluated. Furthermore, the geometric evaluation was extended to investigate the optimal number of fractions necessary to construct the internal target volume (ITV) for the hybrid strategy. The dosimetric margin improvement was smaller than its geometric counterpart and was in the range of 0-1 mm. The optimal number of fractions necessary for the ITV construction is 2 for LRPs and 3-4 for IRPs in a hypofractionation protocol. A new cumulative index of target volume was proposed

Dosimetric Implications of Residual Tracking Errors During Robotic SBRT of Liver Metastases

Energy Technology Data Exchange (ETDEWEB)

Chan, Mark [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Kiel (Germany); Tuen Mun Hospital, Hong Kong (China); Grehn, Melanie [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Lübeck (Germany); Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck (Germany); Cremers, Florian [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Lübeck (Germany); Siebert, Frank-Andre [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Kiel (Germany); Wurster, Stefan [Saphir Radiosurgery Center Northern Germany, Güstrow (Germany); Department for Radiation Oncology, University Medicine Greifswald, Greifswald (Germany); Huttenlocher, Stefan [Saphir Radiosurgery Center Northern Germany, Güstrow (Germany); Dunst, Jürgen [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Kiel (Germany); Department for Radiation Oncology, University Clinic Copenhagen, Copenhagen (Denmark); Hildebrandt, Guido [Department for Radiation Oncology, University Medicine Rostock, Rostock (Germany); Schweikard, Achim [Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck (Germany); Rades, Dirk [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Lübeck (Germany); Ernst, Floris [Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck (Germany); and others

2017-03-15

Purpose: Although the metric precision of robotic stereotactic body radiation therapy in the presence of breathing motion is widely known, we investigated the dosimetric implications of breathing phase–related residual tracking errors. Methods and Materials: In 24 patients (28 liver metastases) treated with the CyberKnife, we recorded the residual correlation, prediction, and rotational tracking errors from 90 fractions and binned them into 10 breathing phases. The average breathing phase errors were used to shift and rotate the clinical tumor volume (CTV) and planning target volume (PTV) for each phase to calculate a pseudo 4-dimensional error dose distribution for comparison with the original planned dose distribution. Results: The median systematic directional correlation, prediction, and absolute aggregate rotation errors were 0.3 mm (range, 0.1-1.3 mm), 0.01 mm (range, 0.00-0.05 mm), and 1.5° (range, 0.4°-2.7°), respectively. Dosimetrically, 44%, 81%, and 92% of all voxels differed by less than 1%, 3%, and 5% of the planned local dose, respectively. The median coverage reduction for the PTV was 1.1% (range in coverage difference, −7.8% to +0.8%), significantly depending on correlation (P=.026) and rotational (P=.005) error. With a 3-mm PTV margin, the median coverage change for the CTV was 0.0% (range, −1.0% to +5.4%), not significantly depending on any investigated parameter. In 42% of patients, the 3-mm margin did not fully compensate for the residual tracking errors, resulting in a CTV coverage reduction of 0.1% to 1.0%. Conclusions: For liver tumors treated with robotic stereotactic body radiation therapy, a safety margin of 3 mm is not always sufficient to cover all residual tracking errors. Dosimetrically, this translates into only small CTV coverage reductions.

Dosimetric Implications of Residual Tracking Errors During Robotic SBRT of Liver Metastases

International Nuclear Information System (INIS)

Chan, Mark; Grehn, Melanie; Cremers, Florian; Siebert, Frank-Andre; Wurster, Stefan; Huttenlocher, Stefan; Dunst, Jürgen; Hildebrandt, Guido; Schweikard, Achim; Rades, Dirk; Ernst, Floris

2017-01-01

Purpose: Although the metric precision of robotic stereotactic body radiation therapy in the presence of breathing motion is widely known, we investigated the dosimetric implications of breathing phase–related residual tracking errors. Methods and Materials: In 24 patients (28 liver metastases) treated with the CyberKnife, we recorded the residual correlation, prediction, and rotational tracking errors from 90 fractions and binned them into 10 breathing phases. The average breathing phase errors were used to shift and rotate the clinical tumor volume (CTV) and planning target volume (PTV) for each phase to calculate a pseudo 4-dimensional error dose distribution for comparison with the original planned dose distribution. Results: The median systematic directional correlation, prediction, and absolute aggregate rotation errors were 0.3 mm (range, 0.1-1.3 mm), 0.01 mm (range, 0.00-0.05 mm), and 1.5° (range, 0.4°-2.7°), respectively. Dosimetrically, 44%, 81%, and 92% of all voxels differed by less than 1%, 3%, and 5% of the planned local dose, respectively. The median coverage reduction for the PTV was 1.1% (range in coverage difference, −7.8% to +0.8%), significantly depending on correlation (P=.026) and rotational (P=.005) error. With a 3-mm PTV margin, the median coverage change for the CTV was 0.0% (range, −1.0% to +5.4%), not significantly depending on any investigated parameter. In 42% of patients, the 3-mm margin did not fully compensate for the residual tracking errors, resulting in a CTV coverage reduction of 0.1% to 1.0%. Conclusions: For liver tumors treated with robotic stereotactic body radiation therapy, a safety margin of 3 mm is not always sufficient to cover all residual tracking errors. Dosimetrically, this translates into only small CTV coverage reductions.

SU-F-T-356: DosimetricComparison of VMAT Vs Step and Shoot IMRT Plans for Stage III Lung CancerPatients with Mediastinal Involvement

Energy Technology Data Exchange (ETDEWEB)

Pearson, D; Bogue, J [University of Toledo, Toledo, OH (United States)

2016-06-15

Purpose: For Stage III lung cancers that entail treatment of some or all of the mediastinum, anterior-posterior focused Step and Shoot IMRT (SS-IMRT) and VMAT plans have been clinically used to deliver the prescribed dose while working to minimize lung dose and avoid other critical structures. A comparison between the two planning methods was completed to see which treatment method is superior and minimizes dose to healthy lung tissue. Methods: Ten patients who were recently treated with SS-IMRT or VMAT plans for Stage III lung cancer with mediastinal involvement were selected. All patients received a simulation CT for treatment planning, as well as a 4D CT and PET/CT fusion for target delineation. Plans were prescribed 6250 cGy in 25 fractions and normalized such that 100% of the prescription dose covered 95% of the PTV. Clinically approved SS-IMRT or VMAT plans were then copied and planned using the alternative modality with identical optimization criteria. SS-IMRT plans utilized seven to nine beams distributed around the patient while the VMAT plans consisted of two full 360 degree arcs. Plans were compared for the lung volume receiving 20 Gy (V20). Results: Both SS-IMRT and VMAT can be used to achieve clinical treatment plans for patients with Stage III Lung cancer with targets encompassing the mediastinum. VMAT plans produced an average V20 of 23.0+/−8.3% and SS-IMRT produced an average of 24.2+/−10.0%. Conclusion: Results indicate that either method can achieve comparable dose distributions, however, VMAT can allow the optimizer to distribute dose over paths of minimal lung tissue and reduce the V20. Therefore, creating a VMAT with constraints identical to an SS-IMRT plan could help to reduce the V20 in clinical treatment plans.

SU-F-T-356: DosimetricComparison of VMAT Vs Step and Shoot IMRT Plans for Stage III Lung CancerPatients with Mediastinal Involvement

International Nuclear Information System (INIS)

Pearson, D; Bogue, J

2016-01-01

Purpose: For Stage III lung cancers that entail treatment of some or all of the mediastinum, anterior-posterior focused Step and Shoot IMRT (SS-IMRT) and VMAT plans have been clinically used to deliver the prescribed dose while working to minimize lung dose and avoid other critical structures. A comparison between the two planning methods was completed to see which treatment method is superior and minimizes dose to healthy lung tissue. Methods: Ten patients who were recently treated with SS-IMRT or VMAT plans for Stage III lung cancer with mediastinal involvement were selected. All patients received a simulation CT for treatment planning, as well as a 4D CT and PET/CT fusion for target delineation. Plans were prescribed 6250 cGy in 25 fractions and normalized such that 100% of the prescription dose covered 95% of the PTV. Clinically approved SS-IMRT or VMAT plans were then copied and planned using the alternative modality with identical optimization criteria. SS-IMRT plans utilized seven to nine beams distributed around the patient while the VMAT plans consisted of two full 360 degree arcs. Plans were compared for the lung volume receiving 20 Gy (V20). Results: Both SS-IMRT and VMAT can be used to achieve clinical treatment plans for patients with Stage III Lung cancer with targets encompassing the mediastinum. VMAT plans produced an average V20 of 23.0+/−8.3% and SS-IMRT produced an average of 24.2+/−10.0%. Conclusion: Results indicate that either method can achieve comparable dose distributions, however, VMAT can allow the optimizer to distribute dose over paths of minimal lung tissue and reduce the V20. Therefore, creating a VMAT with constraints identical to an SS-IMRT plan could help to reduce the V20 in clinical treatment plans.

Comparison between intensity modulated radiotherapy (IMRT) and 3D tangential beams technique used in patients with early-stage breast cancer who received breast-conserving therapy

International Nuclear Information System (INIS)

Sas-Korczynska, B.; Kokoszka, A.; Korzeniowski, S.; Sladowska, A.; Rozwadowska-Bogusz, B.; Lesiak, J.; Dyczek, S.

2010-01-01

Background: The most often found complications in patients with breast cancer who received radiotherapy are cardiac and pulmonary function disorders and development of second malignancies. Aim: To compare the intensity modulated radiotherapy with the 3D tangential beams technique in respect of dose distribution in target volume and critical organs they generate in patients with early-stage breast cancer who received breast-conserving therapy. Materials and methods: A dosimetric analysis was performed to assess the three radiotherapy techniques used in each of 10 consecutive patients with early-stage breast cancer treated with breast-conserving therapy. Radiotherapy was planned with the use of all the three techniques: 3D tangential beams with electron boost, IMRT with electron boost, and intensity modulated radiotherapy with simultaneous integrated boost. Results: The use of the IMRT techniques enables more homogenous dose distribution in target volume. The range of mean and median dose to the heart and lung was lower with the IMRT techniques in comparison to the 3D tangential beams technique. The range of mean dose to the heart amounted to 0.3 - 3.5 Gy for the IMRT techniques and 0.4 - 4.3 for the tangential beams technique. The median dose to the lung on the irradiated side amounted to 4.9 - 5 Gy for the IMRT techniques and 5.6 Gy for the 3D tangential beams technique. Conclusion: The application of the IMRT techniques in radiotherapy patients with early-stage breast cancer allows to obtain more homogenous dose distribution in target volume, while permitting to reduce the dose to critical organs. (authors)

Poster — Thur Eve — 74: Distributed, asynchronous, reactive dosimetric and outcomes analysis using DICOMautomaton

International Nuclear Information System (INIS)

Clark, Haley; Wu, Jonn; Moiseenko, Vitali; Thomas, Steven

2014-01-01

Many have speculated about the future of computational technology in clinical radiation oncology. It has been advocated that the next generation of computational infrastructure will improve on the current generation by incorporating richer aspects of automation, more heavily and seamlessly featuring distributed and parallel computation, and providing more flexibility toward aggregate data analysis. In this report we describe how a recently created — but currently existing — analysis framework (DICOMautomaton) incorporates these aspects. DICOMautomaton supports a variety of use cases but is especially suited for dosimetric outcomes correlation analysis, investigation and comparison of radiotherapy treatment efficacy, and dose-volume computation. We describe: how it overcomes computational bottlenecks by distributing workload across a network of machines; how modern, asynchronous computational techniques are used to reduce blocking and avoid unnecessary computation; and how issues of out-of-date data are addressed using reactive programming techniques and data dependency chains. We describe internal architecture of the software and give a detailed demonstration of how DICOMautomaton could be used to search for correlations between dosimetric and outcomes data

Radiation process control, study and acceptance of dosimetric methods

International Nuclear Information System (INIS)

Radak, B.B.

1984-01-01

The methods of primary dosimetric standardization and the calibration of dosimetric monitors suitable for radiation process control were outlined in the form of a logical pattern in which they are in current use on industrial scale in Yugoslavia. The reliability of the process control of industrial sterilization of medical supplies for the last four years was discussed. The preparatory works for the intermittent use of electron beams in cable industry were described. (author)

Computerized tomography in Community of Madrid. Reference dosimetric measurements

International Nuclear Information System (INIS)

Ruiz Sanz, S.; Calzado, A.; Melchor, M.; Marco, M.

1994-01-01

A total of about 43 computed tomography scanners were operating in the Autonomous Community of Madrid during 1991. A sample of 14 facilities was selected to perform dosimetric measurements in order to obtain characteristic dose profiles. From these, some quantities as the computed tomography dose index and the enhancement factor were calculated and analysed for the most common technique settings. Relations were established between the dosimetric results and technical characteristics of the scanners. (Author)

Cytogenetic and dosimetric effects of {sup 131}I in patients with differentiated thyroid carcinoma: comparison between stimulation with rhTSH and thyroid hormone withdrawal treatments

Energy Technology Data Exchange (ETDEWEB)

Silva, Marcia Augusta da; Gomes Silva Valgode, Flavia; Carvalho Pinto Ribela, Maria Teresa; Bartolini, Paolo; Okazaki, Kayo [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Comissao Nacional de Energia Nuclear (CNEN), IPEN-CNEN/SP, Centro de Biotecnologia, Sao Paulo (Brazil); Armiliato Gonzalez, Julia; Calil Cury Guimaraes, Maria Ines; Buchpiguel, Carlos Alberto [Faculdade de Medicina da Universidade de Sao Paulo, Centro de Medicina Nuclear, Sao Paulo (Brazil); Yoriyaz, Helio [Instituto de Pesquisas Energeticas e Nucleares, IPEN-CNEN/SP, Centro de Engenharia Nuclear, Sao Paulo (Brazil)

2016-08-15

A study directed to the cytogenetic and dosimetric aspects of radionuclides of medical interest is very valuable, both for an accurate evaluation of the dose received by the patients, and consequently of the genetic damage, and for the optimization of therapeutic strategies. Cytogenetic and dosimetric effects of {sup 131}I in lymphocytes of thyroidectomized differentiated thyroid cancer (DTC) patients were evaluated through chromosome aberration (CA) technique: Euthyroid patients submitted to recombinant human thyroid-stimulating hormone (rhTSH) therapy (group A) were compared with hypothyroid patients left without levothyroxine treatment (group B). CA analysis was carried out prior to and 24 h, 1 week, 1 month and 1 year after radioiodine administration (4995-7030 MBq) in both groups. An activity-response curve of {sup 131}I (0.074-0.740 MBq/mL) was elaborated, comparing dicentric chromosomes in vivo and in vitro in order to estimate the absorbed dose through Monte Carlo simulations. In general, radioiodine therapy induced a higher total CA rate in hypothyroid patients as compared to euthyroid patients. The frequencies of dicentrics obtained in DTC patients 24 h after treatment were equivalent to those induced in vitro (0.2903 ± 0.1005 MBq/mL in group A and 0.2391 ± 0.1019 MBq/mL in group B), corresponding to absorbed doses of 0.65 ± 0.23 Gy and 0.53 ± 0.23 Gy, respectively. The effect on lymphocytes of internal radiation induced by {sup 131}I therapy is minimal when based on the frequencies of CA 1 year after the treatment, maintaining a higher quality of life for DTC patients receiving rhTSH-aided therapy. (orig.)

First approval procedure of the TL dosimetric service of the NPP in Slovenia

International Nuclear Information System (INIS)

Janzekovic, H.; Krizman, M.; Pucelj, B.; Stuhec, M.; Zdesar, U.

2001-01-01

The individual dosimetry of exposed workers in a NPP is one of the essential parts which demonstrates the radiation protection standards achieved in a facility. According to the current legislation the Ministry of Health of the Republic of Slovenia has the authority to grant approvals to personal dosimetric services which perform the dosimetric monitoring of workers in Slovenia. Due to the fact that the detailed approval procedure is not given in national regulations, the Ministry of Health in 2000 established a group of experts with the task to prepare technical and organising requirements for such approval. Based on international documents [1,2,3] the Approval procedure for the thermoluminescence dosimetric (TL) services was created. Following this procedure the assessment of the TL dosimetric service in the NPP was performed. The problems related to the technical and organising requirements with the emphasise on the QA/QC criteria of the TL dosimetric service will be discussed.(author)

A Dosimetric Comparison between Conventional Fractionated and Hypofractionated Image-guided Radiation Therapies for Localized Prostate Cancer

Directory of Open Access Journals (Sweden)

Ming Li

2016-01-01

Conclusions: To deliver the hypofractionated radiotherapy in prostate cancer, VMAT significantly increased PTV D95% dose and decreased the dose of radiation delivered to adjacent normal tissues comparing to 7-field, step-and-shoot IMRT. Daily online image-guidance and better management of bladder and rectum could make a more precise treatment delivery.

Clinical experience transitioning from IMRT to VMAT for head and neck cancer

Energy Technology Data Exchange (ETDEWEB)

Studenski, Matthew T., E-mail: matthew.studenski@jeffersonhospital.org [Department of Radiation Oncology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA (United States); Bar-Ad, Voichita; Siglin, Joshua [Department of Radiation Oncology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA (United States); Cognetti, David; Curry, Joseph [Department of Otolaryngology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA (United States); Tuluc, Madalina [Department of Pathology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA (United States); Harrison, Amy S. [Department of Radiation Oncology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA (United States)

2013-07-01

To quantify clinical differences for volumetric modulated arc therapy (VMAT) versus intensity modulated radiation therapy (IMRT) in terms of dosimetric endpoints and planning and delivery time, twenty head and neck cancer patients have been considered for VMAT using Nucletron Oncentra MasterPlan delivered via an Elekta linear accelerator. Differences in planning time between IMRT and VMAT were estimated accounting for both optimization and calculation. The average delivery time per patient was obtained retrospectively using the record and verify software. For the dosimetric comparison, all contoured organs at risk (OARs) and planning target volumes (PTVs) were evaluated. Of the 20 cases considered, 14 had VMAT plans approved. Six VMAT plans were rejected due to unacceptable dose to OARs. In terms of optimization time, there was minimal difference between the two modalities. The dose calculation time was significantly longer for VMAT, 4 minutes per 358 degree arc versus 2 minutes for an entire IMRT plan. The overall delivery time was reduced by 9.2 ± 3.9 minutes for VMAT (51.4 ± 15.6%). For the dosimetric comparison of the 14 clinically acceptable plans, there was almost no statistical difference between the VMAT and IMRT. There was also a reduction in monitor units of approximately 32% from IMRT to VMAT with both modalities demonstrating comparable quality assurance results. VMAT provides comparable coverage of target volumes while sparing OARs for the majority of head and neck cases. In cases where high dose modulation was required for OARs, a clinically acceptable plan was only achievable with IMRT. Due to the long calculation times, VMAT plans can cause delays during planning but marked improvements in delivery time reduce patient treatment times and the risk of intra-fraction motion.

Dosimetric Predictors of Duodenal Toxicity After Intensity Modulated Radiation Therapy for Treatment of the Para-aortic Nodes in Gynecologic Cancer

Energy Technology Data Exchange (ETDEWEB)

Verma, Jonathan [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States); Sulman, Erik P.; Jhingran, Anuja [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Tucker, Susan L. [Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Rauch, Gaiane M. [Department of Radiology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Eifel, Patricia J. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Klopp, Ann H., E-mail: aklopp@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

2014-02-01

Purpose: To determine the incidence of duodenal toxicity in patients receiving intensity modulated radiation therapy (IMRT) for treatment of para-aortic nodes and to identify dosimetric parameters predictive of late duodenal toxicity. Methods and Materials: We identified 105 eligible patients with gynecologic malignancies who were treated with IMRT for gross metastatic disease in the para-aortic nodes from January 1, 2005, through December 31, 2009. Patients were treated to a nodal clinical target volume to 45 to 50.4 Gy with a boost to 60 to 66 Gy. The duodenum was contoured, and dosimetric data were exported for analysis. Duodenal toxicity was scored according to Radiation Therapy Oncology Group criteria. Univariate Cox proportional hazards analysis and recursive partitioning analysis were used to determine associations between dosimetric variables and time to toxicity and to identify the optimal threshold that separated patients according to risk of toxicity. Results: Nine of the 105 patients experienced grade 2 to grade 5 duodenal toxicity, confirmed by endoscopy in all cases. The 3-year actuarial rate of any duodenal toxicity was 11.7%. A larger volume of the duodenum receiving 55 Gy (V55) was associated with higher rates of duodenal toxicity. The 3-year actuarial rates of duodenal toxicity with V55 above and below 15 cm{sup 3} were 48.6% and 7.4%, respectively (P<.01). In Cox univariate analysis of dosimetric variables, V55 was associated with duodenal toxicity (P=.029). In recursive partitioning analysis, V55 less than 13.94% segregated all patients with duodenal toxicity. Conclusions: Dose-escalated IMRT can safely and effectively treat para-aortic nodal disease in gynecologic malignancies, provided that care is taken to limit the dose to the duodenum to reduce the risk of late duodenal toxicity. Limiting V55 to below 15 cm{sup 3} may reduce the risk of duodenal complications. In cases where the treatment cannot be delivered within these constraints

Dosimetric study comparing volumetric arc modulation with RapidArc and fixed dynamic intensity-modulated radiation therapy for breast cancer radiotherapy after breast-conserving surgery

International Nuclear Information System (INIS)

Tie Jian; Sun Yan; Gong Jian; Han Shukui; Jiang Fan; Wu Hao

2011-01-01

Objective: To compare the dosimetric difference between volumetric are modulation with RapidArc and fixed field dynamic IMRT for breast cancer radiotherapy after breast-conserving surgery. Methods: Twenty patients with early left-sided breast cancer received radiotherapy after breast-conserving surgery. After target definition, treatment planning was performed by RapidArc and two fixed fields dynamic IMRT respectively on the same CT scan. The target dose distribution, homogeneity of the breast, and the irradiation dose and volume for the lungs, heart, and contralateral breast were read in the dose-volume histogram (DVH) and compared between RapidArc and IMRT. The treatment delivery time and monitor units were also compared. Results: In comparison with the IMRT planning,the homogeneity of clinical target volume (CTV), the volume proportion of 95% prescribed dose (V 95% ) was significantly higher by 0.65% in RapidArc (t=5.16, P=0.001), and the V 105% and V 110% were lower by 10.96% and 1.48 % respectively, however, without statistical significance (t=-2.05, P=0.055 and t=-1.33, P=0.197). The conformal index of planning target volume (PTV) by the RapidArc planning was (0.88±0.02), significantly higher than that by the IMRT planning [(0.74±0.03), t=18.54, P<0.001]. The homogeneity index (HI) of PTV by the RapidArc planning was 1.11±0.01, significantly lower than that by the IMRT planning (1.12±0.02, t=-2.44, P=0.02). There were no significant differences in the maximum dose (D max ) and V 20 for the ipsilateral lung between the RapidArc and IMRT planning, but the values of V 10 , V 5 , D min and D mean by RapidArc planning were all significantly higher than those by the IMRT planning (all P<0.01). The values of max dose and V 30 for the heart were similar by both techniques, but the values of V 10 and V 5 by the RapidArc planning were significantly higher (by 18% and 50%, respectively). The V 5 of the contralateral breast and lung by the RapidArc planning were

Biokinetic and dosimetric studies of 188Re-hyaluronic acid: a new radiopharmaceutical for treatment of hepatocellular carcinoma

International Nuclear Information System (INIS)

Melendez-Alafort, Laura; Nadali, Anna; Zangoni, Elena; Banzato, Alessandra; Rondina, Maria; Rosato, Antonio; Mazzi, Ulderico

2009-01-01

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and has very limited therapeutic options. Recently, it has been found that hyaluronic acid (HA) shows selective binding to CD44 receptors expressed in most cancer histotypes. Since the trend in cancer treatment is the use of targeted radionuclide therapy, the aim of this research was to label HA with rhenium-188 and to evaluate its potential use as a hepatocarcinoma therapeutic radiopharmaceutical. Methods: 188 Re-HA was prepared by a direct labelling method to produce a ReO(O-COO) 2 -type coordination complex. 188 Re-HA protein binding and its stability in saline, phosphate buffer, human serum and cysteine solutions were determined. Biokinetic and dosimetric data were estimated in healthy mice (n=60) using the Medical Internal Radiation Dose methodology and mouse model beta-absorbed fractions. To evaluate liver toxicity, alanine aminotranferase (AST) and aspartate aminotranferase (ALT) levels in mice were assessed and the liver maximum tolerated dose (MTD) of 188 Re-HA was determined. Results: A stable complex of 188 Re-HA was obtained with high radiochemical purity (>90%) and low serum protein binding (2%). Biokinetic studies showed a rapid blood clearance (T 1/2 α=21 min). Four hours after administration, 188 Re-HA was almost totally removed from the blood by the liver due to the selective uptake via HA-specific receptors (73.47±5.11% of the injected dose). The liver MTD in mice was ∼40 Gy after 7.4 MBq of 188 Re-HA injection. Conclusions: 188 Re-HA complex showed good stability, pharmacokinetic and dosimetric characteristics that confirm its potential as a new agent for HCC radiation therapy.

TU-CD-304-03: Dosimetric Verification and Preliminary Comparison of Dynamic Wave Arc for SBRT Treatments

Energy Technology Data Exchange (ETDEWEB)

Burghelea, M [UZ BRUSSEL, Brussels (Belgium); BRAINLAB AG, Munich (Germany); Babes Bolyai University, Cluj-Napoca (Romania); Poels, K; Gevaert, T; Tournel, K; Dhont, J; De Ridder, M; Verellen, D [UZ BRUSSEL, Brussels (Belgium); Hung, C [BRAINLAB AG, Munich (Germany); Eriksson, K [RAYSEARCH LABORATORIES AB, Stockholm (Sweden); Simon, V [Babes Bolyai University, Cluj-Napoca (Romania)

2015-06-15

Purpose: To evaluate the potential dosimetric benefits and verify the delivery accuracy of Dynamic Wave Arc, a novel treatment delivery approach for the Vero SBRT system. Methods: Dynamic Wave Arc (DWA) combines simultaneous movement of gantry/ring with inverse planning optimization, resulting in an uninterrupted non-coplanar arc delivery technique. Thirteen SBRT complex cases previously treated with 8–10 conformal static beams (CRT) were evaluated in this study. Eight primary centrally-located NSCLC (prescription dose 4×12Gy or 8×7.5Gy) and five oligometastatic cases (2×2 lesions, 10×5Gy) were selected. DWA and coplanar VMAT plans, partially with dual arcs, were generated for each patient using identical objective functions for target volumes and OARs on the same TPS (RayStation, RaySearch Laboratories). Dosimetric differences and delivery time among these three planning schemes were evaluated. The DWA delivery accuracy was assessed using the Delta4 diode array phantom (ScandiDos AB). The gamma analysis was performed with the 3%/3mm dose and distance-to-agreement criteria. Results: The target conformity for CRT, VMAT and DWA were 0.95±0.07, 0.96±0.04 and 0.97±0.04, while the low dose spillage gradient were 5.52±1.36, 5.44±1.11, and 5.09±0.98 respectively. Overall, the bronchus, esophagus and spinal cord maximum doses were similar between VMAT and DWA, but highly reduced compared with CRT. For the lung cases, the mean dose and V20Gy were lower for the arc techniques compares with CRT, while for the liver cases, the mean dose and the V30Gy presented slightly higher values. The average delivery time of VMAT and DWA were 2.46±1.10 min and 4.25±1.67 min, VMAT presenting shorter treatment time in all cases. The DWA dosimetric verification presented an average gamma index passing rate of 95.73±1.54% (range 94.2%–99.8%). Conclusion: Our preliminary data indicated that the DWA is deliverable with clinically acceptable accuracy and has the potential to

TU-CD-304-03: Dosimetric Verification and Preliminary Comparison of Dynamic Wave Arc for SBRT Treatments

International Nuclear Information System (INIS)

Burghelea, M; Poels, K; Gevaert, T; Tournel, K; Dhont, J; De Ridder, M; Verellen, D; Hung, C; Eriksson, K; Simon, V

2015-01-01

Purpose: To evaluate the potential dosimetric benefits and verify the delivery accuracy of Dynamic Wave Arc, a novel treatment delivery approach for the Vero SBRT system. Methods: Dynamic Wave Arc (DWA) combines simultaneous movement of gantry/ring with inverse planning optimization, resulting in an uninterrupted non-coplanar arc delivery technique. Thirteen SBRT complex cases previously treated with 8–10 conformal static beams (CRT) were evaluated in this study. Eight primary centrally-located NSCLC (prescription dose 4×12Gy or 8×7.5Gy) and five oligometastatic cases (2×2 lesions, 10×5Gy) were selected. DWA and coplanar VMAT plans, partially with dual arcs, were generated for each patient using identical objective functions for target volumes and OARs on the same TPS (RayStation, RaySearch Laboratories). Dosimetric differences and delivery time among these three planning schemes were evaluated. The DWA delivery accuracy was assessed using the Delta4 diode array phantom (ScandiDos AB). The gamma analysis was performed with the 3%/3mm dose and distance-to-agreement criteria. Results: The target conformity for CRT, VMAT and DWA were 0.95±0.07, 0.96±0.04 and 0.97±0.04, while the low dose spillage gradient were 5.52±1.36, 5.44±1.11, and 5.09±0.98 respectively. Overall, the bronchus, esophagus and spinal cord maximum doses were similar between VMAT and DWA, but highly reduced compared with CRT. For the lung cases, the mean dose and V20Gy were lower for the arc techniques compares with CRT, while for the liver cases, the mean dose and the V30Gy presented slightly higher values. The average delivery time of VMAT and DWA were 2.46±1.10 min and 4.25±1.67 min, VMAT presenting shorter treatment time in all cases. The DWA dosimetric verification presented an average gamma index passing rate of 95.73±1.54% (range 94.2%–99.8%). Conclusion: Our preliminary data indicated that the DWA is deliverable with clinically acceptable accuracy and has the potential to

SU-E-T-124: Dosimetric Comparison of HDR Brachytherapy and Intensity Modulated Proton Therapy

Energy Technology Data Exchange (ETDEWEB)

Wu, J [Purdue University, West Lafayette, IN (United States); Wu, H [IUPUI, Indianapolis, IN (United States); Das, I [Indiana University- School of Medicine, Indianapolis, IN (United States)

2014-06-01

Purpose: Brachytherapy is known to be able to deliver more radiation dose to tumor while minimizing radiation dose to surrounding normal tissues. Proton therapy also provides superior dose distribution due to Bragg peak. Since both HDR and Intensity Modulated Proton Therapy (IMPT) are beneficial for their quick dose drop off, our goal in this study is to compare the pace of dose gradient drop-off between HDR and IMPT plans based on the same CT image data-set. In addition, normal tissues sparing were also compared among HDR, IMPT and SBRT. Methods: Five cervical cancer cases treated with EBRT + HDR boost combination with Tandem and Ovoid applicator were used for comparison purpose. Original HDR plans with prescribed dose of 5.5 Gy x 5 fractions were generated and optimized. The 100% isodose line of HDR plans was converted to a dose volume, and treated as CTV for IMPT and SBRT planning. The same HDR CT scans were also used for IMPT plan and SBRT plan for direct comparison. The philosophy of the IMPT and SBRT planning was to create the same CTV coverage as HDR plans. All three modalities treatment plans were compared to each other with a set of predetermined criteria. Results: With similar target volume coverage in cervix cancer boost treatment, HDR provides a slightly sharper dose drop-off from 100% to 50% isodose line, averagely in all directions compared to IMPT. However, IMPT demonstrated more dose gradient drop-off at the junction of the target and normal tissues by providing more normal tissue sparing and superior capability to reduce integral dose. Conclusion: IMPT is capable of providing comparable dose drop-off as HDR. IMPT can be explored as replacement for HDR brachytherapy in various applications.

The role of the Secondary Laboratory of Dosimetric calibration in the implementation of the dosimetric magnitudes with radiological protection aims

International Nuclear Information System (INIS)

Perez Medina O, V.; Alvarez R, J.T.; Tovar M, V.M.

2006-01-01

It is very well-known the paper of the net of secondary laboratories of dosimetric calibration of the OAS in the dissemination of the traceability of the dosimetric magnitudes: kerma in air and absorbed dose in water, to the radiotherapy departments, given the high accuracy and precision that require the radiotherapy treatments. However the LSCD has other important areas at least for the development, implementation and evaluation of dosimetric magnitudes denominated operative magnitudes with ends of radiological protection: environmental equivalent dose H*(10), directional equivalent dose H'(0.07) and personal equivalent dose Hp. In the case of radiological protection the LSCD-ININ has been implementing the infrastructure to give service of personal dosimetry for photons and beta particles in terms of the operative magnitudes. For photons: X and gamma rays, it account with a secondary pattern camera PTW T34035 gauged in H * and Hp in the primary laboratory of Germany PTB. For the case of beta radiation its account with an extrapolation camera PTW 23392 with a secondary pattern kit of sources of the type I, gauged in terms of H'(0.07) in the PTB. (Author)

CT and MR image fusion using two different methods after prostate brachytherapy: impact on post-implant dosimetric assessment

International Nuclear Information System (INIS)

Servois, V.; El Khoury, C.; Lantoine, A.; Ollivier, L.; Neuenschwander, S.; Chauveinc, L.; Cosset, J.M.; Flam, T.; Rosenwald, J.C.

2003-01-01

To study different methods of CT and MR images fusion in patient treated by brachytherapy for localized prostate cancer. To compare the results of the dosimetric study realized on CT slices and images fusion. Fourteen cases of patients treated by 1125 were retrospectively studied. The CT examinations were realized with continuous section of 5 mm thickness, and MR images were obtained with a surface coil with contiguous section of 3 mm thickness. For the images fusion process, only the T2 weighted MR sequence was used. Two processes of images fusion were realized for each patient, using as reference marks the bones of the pelvis and the implanted seeds. A quantitative and qualitative appreciation was made by the operators, for each patient and both methods of images fusion. The dosimetric study obtained by a dedicated software was realized on CT images and all types of images fusion. The usual dosimetric indexes (D90, V 100 and V 150) were compared for each type of image. The quantitative results given by the software of images fusion showed a superior accuracy to the one obtained by the pelvic bony reference marks. Conversely, qualitative and quantitative results obtained by the operators showed a better accuracy of the images fusion based on iodine seeds. For two patients out of three presenting a D90 inferior to 145 Gy on CT examination, the D90 was superior to this norm when the dosimetry was based on images fusion, whatever the method used. The images fusion method based on implanted seed matching seems to be more precise than the one using bony reference marks. The dosimetric study realized on images fusion could allow to rectify possible errors, mainly due to difficulties in surrounding prostate contour delimitation on CT images. (authors)

Dosimetric monitoring at time of Chernobyl clean-up. A retrospective view

International Nuclear Information System (INIS)

Chumak, V.V.; Bakhanova, E.V.; Musijachenko, N.V.; Krjuchkov, V.P.

2000-01-01

Although at time of the accident many thousands of individuals were subjected to personal dosimetric monitoring, a status of dosimetric support of clean-up activities performed in 1986-1987 remains one of the most uncertain radiological issues related to Chernobyl accident. It is known that the scope, practical coverage and methodologies of dosimetry at time of the accident significantly varied. Unfortunately, the dose records available now in a number registries and databases are lacking direct indications of the methods of dosimetry, locations of work and tasks performed by liquidators. Moreover, data record linkage in many cases is problematic due to lack of unique identifiers in the databases of concern. However, this information, collected in course of dosimetric monitoring is extremely valuable for epidemiological consideration of this cohort and, therefore, cannot be neglected because of problems with strait forward application of this data. Retrospective consideration of dosimetric monitoring data was conducted along several lines. First, data sets (in some cases impersonal), related to the known dosimetric practices were studied in order to determine regularities in their dose distributions, evaluate possible distortions caused by extraneous admixtures to dose arrays and evaluate possible contribution of falsified dose records. Another effort was directed towards individualization of information regarding affiliation and tasks of the liquidators included into the State Chernobyl Registry (SCR), which is, essentially, the main pool of subjects for observation in the framework of post Chernobyl epidemiological studies. The SCR in its original shape was missing this crucial information. In order to recover this information gap, a wide scale postal survey of liquidators was undertaken. Those persons who are included into the State Chernobyl Registry and have official dose records were asked to respond to a simple five-entry questionnaire, dealing with their

Loading pattern calculated by inverse optimization vs traditional dosimetry systems of intracavitary brachytherapy of cervical cancer: a dosimetric study

International Nuclear Information System (INIS)

Jamema, S.V.; Deshpande, D.D.; Kirisits, C.; Trnkova, P.; Poetter, R.; Mahantshetty, U.; Shrivastava, S.K.; Dinshaw, K.A.

2008-01-01

In the recent past, inverse planning algorithms were introduced for intracavitary brachytherapy planning (ICBT) for cervical cancer. The loading pattern of these algorithms in comparison with traditional systems may not be similar. The purpose of this study was to objectively compare the loading patterns of traditional systems with the inverse optimization. Based on the outcome of the comparison, an attempt was made to obtain a loading pattern that takes into account the experience made with the inverse optimization

Transport and dosimetric solutions for the ELIMED laser-driven beam line

Energy Technology Data Exchange (ETDEWEB)

Cirrone, G.A.P. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Romano, F. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Medical Physics School, University of Catania, Via S. Sofia 64 - 95125 Catania (Italy); Scuderi, V. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, Na Slovance 2, 182 21 Prague (Czech Republic); Amato, A. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Candiano, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Medical Physics School, University of Catania, Via S. Sofia 64 - 95125 Catania (Italy); Cuttone, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Giove, D. [INFN Sezione di Milano, Via Celoria 16, Milano (Italy); Korn, G.; Krasa, J. [Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, Na Slovance 2, 182 21 Prague (Czech Republic); Leanza, R. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Universitá degli Studi di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Manna, R. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Maggiore, M. [INFN-LNL, Viale dell' Universitá 2 - 35020 Legnaro (PD) (Italy); Marchese, V. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Margarone, D. [Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, Na Slovance 2, 182 21 Prague (Czech Republic); Milluzzo, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Universitá degli Studi di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Petringa, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Sabini, M.G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Azienda Ospedaliera Cannizzaro, Via Messina 829 - 95100 Catania (Italy); Schillaci, F. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Medical Physics School, University of Catania, Via S. Sofia 64 - 95125 Catania (Italy); and others

2015-10-01

Within 2017, the ELIMED (ELI-Beamlines MEDical applications) transport beam-line and dosimetric systems for laser-generated beams will be installed at the ELI-Beamlines facility in Prague (CZ), inside the ELIMAIA (ELI Multidisciplinary Applications of laser–Ion Acceleration) interaction room. The beam-line will be composed of two sections: one in vacuum, devoted to the collecting, focusing and energy selection of the primary beam and the second in air, where the ELIMED beam-line dosimetric devices will be located. This paper briefly describes the transport solutions that will be adopted together with the main dosimetric approaches. In particular, the description of an innovative Faraday Cup detector with its preliminary experimental tests will be reported.

Improvements in critical dosimetric endpoints using the Contura multilumen balloon breast brachytherapy catheter to deliver accelerated partial breast irradiation: preliminary dosimetric findings of a phase iv trial.

Science.gov (United States)

Arthur, Douglas W; Vicini, Frank A; Todor, Dorin A; Julian, Thomas B; Lyden, Maureen R

2011-01-01

Dosimetric findings in patients treated with the Contura multilumen balloon (MLB) breast brachytherapy catheter to deliver accelerated partial breast irradiation (APBI) on a multi-institutional Phase IV registry trial are presented. Computed tomography-based three-dimensional planning with dose optimization was performed. For the trial, new ideal dosimetric goals included (1) ≥95% of the prescribed dose (PD) covering ≥90% of the target volume, (2) a maximum skin dose ≤125% of the PD, (3) maximum rib dose ≤145% of the PD, and (4) the V150 ≤50 cc and V200 ≤10 cc. The ability to concurrently achieve these dosimetric goals using the Contura MLB was analyzed. 144 cases were available for review. Using the MLB, all dosimetric criteria were met in 76% of cases. Evaluating dosimetric criteria individually, 92% and 89% of cases met skin and rib dose criteria, respectively. In 93% of cases, ideal target volume coverage goals were met, and in 99%, dose homogeneity criteria (V150 and V200) were satisfied. When skin thickness was ≥5 mm to <7 mm, the median skin dose was limited to 120.1% of the PD, and when skin thickness was <5 mm, the median skin dose was 124.2%. When rib distance was <5 mm, median rib dose was reduced to 136.5% of the PD. When skin thickness was <7 mm and distance to rib was <5 mm, median skin and rib doses were jointly limited to 120.6% and 142.1% of the PD, respectively. The Contura MLB catheter provided the means of achieving the imposed higher standard of dosimetric goals in the majority of clinical scenarios encountered. Copyright © 2011 Elsevier Inc. All rights reserved.

Dosimetric al confirmation of a software for the design of radiotherapy treatments

International Nuclear Information System (INIS)

Alfonso, Rodolfo; Huerta, Ubaldo; Torres, Miguel; Alonso, Jose L.

1995-01-01

A software for the planning of treatments of Radiotherapy was developed recently by medical physics of the Hospital Clinicoquirurgico Hermanos Ameijeiras, to evaluate the dependability of the results of the dose distributions calculated in the patients, localizations were chosen in the region of the head and the neck and I take like reference the results of measurement dosimetric with powder TLD-700 in a human phantoms. The different options are explained for the entrance of data of the patient's contours. A comparison of the results of the mensurations is shown with those calculated. The causes of the discrepancies are analyzed and recommendations are made regarding the utility of the different options of acquisition of the patient's data

Personal dosimetric monitoring in Ukraine: current status and further development

International Nuclear Information System (INIS)

Chumak, V. V.; Musijachenkom, A. V.; Boguslavskaya, A. I.

2003-01-01

Presently Ukraine has mixed system for dosimetric monitoring. Nuclear power plants and some major nuclear facilities have their own dosimetry services, which are responsible for regular dosimetric monitoring of workers. Rest of occupationally exposed persons is monitored by dosimetry laboratories affiliated to the territorial authorities for sanitary and epidemiology supervision. In 2002-2003 Ukrainian Ministry of Health performed survey of the status of dosimetric monitoring and inventory of critical groups requiring such monitoring. Dosimetry services in Ukraine cover about 38,000 occupationally exposed workers, including 9,100 medical professionals, 16,400 employees of 5 nuclear power plants and ca.12,400 workers dealing with other sources of occupational exposure (industry, research). Territorial dosimetry services operate in 13 of 24 regions of Ukraine, using DTU-01 manual TLD readers produced with one exception in 1988-1990. The coverage of critical groups by dosimetric monitoring is variable and ranges from 38% to 100% depending on the region. Personnel of nuclear power plants (about 16,400 workers) is monitored by their own dosimetry services achieving absolute coverage of the main staff and temporary workers. Current inadequate status of dosimetric monitoring infrastructure in Ukraine demands an urgent elaboration of the united state system for monitoring and recording of individual doses. The proposed plan would allows to bring dosimetry infrastructure in Ukraine to the modern state which would be compatible with existing and future European and international radiation protection networks. Unitary structure of Ukraine, strong administrative command and good communications between regions of the country are positive factors in favour of efficient implementation of the proposed plan. Deficiencies are associated with limited funding of this effort. (authors)

Dosimetric monitoring in Ukraine - present status and path to the future

International Nuclear Information System (INIS)

Chumak, V.; Boguslavskaya, A.

2005-01-01

Full text: Ukraine is the country which utilizes radiation in many peaceful areas. So, nuclear energy sector includes 15 power units (including two new units commissioned in 2004), nuclear fuel cycle also include uranium mines, radiation sources are widely used in industry, science and medicine. As a result, about 50,000 occupationally exposed workers require dosimetric monitoring. However, presently dosimetry services in Ukraine cover only about 38,000 occupationally exposed workers, including 9,100 medical professionals, 16,400 employees of 5 nuclear power plants and ca. 12,400 workers dealing with other sources of occupational exposure (industry, research). Territorial dosimetry services, responsible for dosimetric monitoring in industry and medicine operate in 13 of 25 oblasts (regions) of Ukraine. The coverage of critical groups by dosimetric monitoring is variable and ranges from 38 % to 100 % depending on the oblast. With rare exception, instrumentation is represented by outdated manual TLD systems (inaccurate and insufficiently sensitive) capable of measurement of deep photon dose only; no personal monitoring of beta and neutron exposure is possible now. Quality assurance is limited to the annual metrological attestation of the dosimetric instruments. No information exchange infrastructure and dosimetric registry are in place. The dosimetric data is stored in home-made data environments or even in paper log-books, no data on individual doses is conveyed to central depository, which could be easily accessible for regulating authorities. Although the standing law requires elaboration of the United System for monitoring and registration individual doses, little was done so far, mainly due to lack of domestic funding. However, intention is strong to build such network in accordance with the best practice, covering not only the aspects of physical measurement and data storage, but also quality assurance, accreditation programs and training of the local personnel

Dosimetric assessment of the PRESAGE dosimeter for a proton pencil beam

International Nuclear Information System (INIS)

Wuu, C-S; Qian, X; Xu, Y; Adamovics, J; Cascio, E; Lu, H-M

2013-01-01

The objective of this study is to assess the feasibility of using PRESAGE dosimeters for proton pencil beam dosimetry. Two different formulations of phantom materials were tested for their suitability in characterizing a single proton pencil beam. The dosimetric response of PRESAGE was found to be linear up to 4Gy. First-generation optical CT scanner, OCTOPUS TM was used to implement dose distributions for proton pencil beams since it provides most accurate readout. Percentage depth dose curves and beam profiles for two proton energy, 110 MeV, and 93 MeV, were used to evaluate the dosimetric performance of two PRESAGE phantom formulas. The findings from this study show that the dosimetric properties of the phantom materials match with basic physics of proton beams.

Radiation hazards in uranium mining. Epidemiological and dosimetric approaches

International Nuclear Information System (INIS)

Myers, D.K.; Johnson, J.R.

1989-01-01

Potential health hazards resulting from exposure to various sources of radiation associated with uranium mining have been reviewed: 1) epidemiological observations on groups of miners exposed in the past to high concentrations of radon progeny have been interpreted to suggest a lifetime risk of about 3 x 10 -4 lung cancers per WLM; 2) the total risk of serious health effects resulting from exposure of workers to whole body gamma-radiation might be taken to be about 2 x 10 -2 per Sv; and 3) the potential health effects of inhalation of thoron progeny or of radioactive ore dusts can only be estimated from dosimetric calculations. A review of the uncertainties involved in these calculations suggests that ICRP estimates of the potential toxicity of inhaled thoron progeny are as good as those for inhaled radon progeny. However, the potential health hazards from inhaled uranium and thorium ore dusts have probably been overestimated by a factor of 2 to 10-fold

Dosimetric analysis of radiation sources for use dermatological lesions

International Nuclear Information System (INIS)

Tada, Ariane

2010-01-01

Skin lesions undergoing therapy with radiation sources may have different patterns of malignancy. Malignant lesions or cancer most commonly found in radiotherapy services are carcinomas. Radiation therapy in skin lesions is performed with low penetration beams and orthovoltage X-rays, electron beams and radioactive sources ( 192 Ir, 198 Au, e 90 Sr) arranged on a surface mold or in metal applicator. This study aims to analyze the therapeutic radiation dose profile produced by radiation sources used in skin lesions radiotherapy procedures . Experimental measurements for the analysis of dosimetric radiation sources were compared with calculations obtained from a computer system based on the Monte Carlo Method. Computational results had a good agreement with the experimental measurements. Experimental measurements and computational results by the MCNP4C code were both physically consistent as expected. These experimental measurements compared with calculations using the MCNP-4C code have been used to validate the calculations obtained by MCNP code and to provide a reliable medical application for each clinical case. (author)

Robotic radiotherapy for prostate cancer with CyberKnife

International Nuclear Information System (INIS)

Hannoun-Levi, J.M.; Benezery, K.; Bondiau, P.Y.; Marcie, S.; Gerard, J.P.; Chamorey, E.

2007-01-01

After 3D conformal radiation therapy without and with modulated intensity, image-guided radiation therapy represents a new technological step. Should prostate cancer treatment using radiotherapy with the CyberKnife robotic system be considered as a new treatment and then investigated through classical clinical research procedure rather than a technical improvement of an already validated treatment? After a general presentation of the CyberKnife, the authors focused on prostate cancer treatment assuming that, according to dosimetric and biological considerations, the treatment by robotic system appears comparable to high dose rate brachytherapy. For prostate cancer treatment are discussed: biological rational for hypo fractionated treatment, high dose rate brachytherapy boost and interest of dose escalation. A comparison is presented between CyberKnife and other validated treatment for prostate cancer (radical prostatectomy, 3D conformal radiation therapy and low and high dose rate brachytherapy). In summary, CyberKnife treatment could be considered as a technical improvement of an already validated treatment in order to deliver a prostate boost after pelvic or peri-prostatic area irradiation. However, the clinical, biological and economical results must be precisely analyzed and could be assessed in the frame of a National Observatory based on shared therapeutic program. (authors)

Preliminary dosimetric methodology for a new cobalt-60 irradiator for radioinduced necrosis

International Nuclear Information System (INIS)

Moura, Eduardo S.; Mosca, Rodrigo C.; Zeituni, Carlos A.; Rostelato, Maria Elisa C.M.; Mathor, Monica B.; Sakuraba, Roberto K.; Goncalves, Vinicius D.

2011-01-01

The use of ionizing radiation in medical procedures, as radiotherapy, is a well-established clinical process and it has been used for several decades with good clinical results and continuous technology development for treatment optimization. On the contrary, some injuries such as necrosis, may occur with patients, due to wrong administration of the absorbed dose or with expected side effects. To evaluate how these injuries could be investigated and how they can be treated, a new Cobalto-60 irradiator was developed to induce radionecrosis in mice. This irradiator is composed by a cylindrical size and it was set up with eleven Cobalt-60 sources aligned in the surface of a cylindrical lead. This alignment guarantees a small dose focal area in a longitudinal table, with proper frames for positioning mice precisely during the irradiations period. The dosimetric procedure will measure the absorbed dose in the dose focal area, delimited the area of irradiation with penumbra regions (gradients absorbed dose profiles) and others anatomical regions of the mice with high radiosensitivity. Possible dosimetric procedures and related devices will be present in this work,. The obtained dosimetric data will be applied to ensure the accurate period of radiation of a given position. This preliminary study assures that the fundamental dosimetric process of this new Cobalt-60 irradiator and it predicates that dosimetric processes area feasible to be conducted. (author)

Preliminary dosimetric methodology for a new cobalt-60 irradiator for radioinduced necrosis

Energy Technology Data Exchange (ETDEWEB)

Moura, Eduardo S.; Mosca, Rodrigo C.; Zeituni, Carlos A.; Rostelato, Maria Elisa C.M.; Mathor, Monica B., E-mail: esmoura@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Sakuraba, Roberto K.; Goncalves, Vinicius D. [Hospital Israelita Albert Einstein (HIAE), Sao Paulo, SP (Brazil)

2011-07-01

The use of ionizing radiation in medical procedures, as radiotherapy, is a well-established clinical process and it has been used for several decades with good clinical results and continuous technology development for treatment optimization. On the contrary, some injuries such as necrosis, may occur with patients, due to wrong administration of the absorbed dose or with expected side effects. To evaluate how these injuries could be investigated and how they can be treated, a new Cobalto-60 irradiator was developed to induce radionecrosis in mice. This irradiator is composed by a cylindrical size and it was set up with eleven Cobalt-60 sources aligned in the surface of a cylindrical lead. This alignment guarantees a small dose focal area in a longitudinal table, with proper frames for positioning mice precisely during the irradiations period. The dosimetric procedure will measure the absorbed dose in the dose focal area, delimited the area of irradiation with penumbra regions (gradients absorbed dose profiles) and others anatomical regions of the mice with high radiosensitivity. Possible dosimetric procedures and related devices will be present in this work,. The obtained dosimetric data will be applied to ensure the accurate period of radiation of a given position. This preliminary study assures that the fundamental dosimetric process of this new Cobalt-60 irradiator and it predicates that dosimetric processes area feasible to be conducted. (author)

Dosimetric study of RapidArc plans with flattened beam (FB and flattening filter-free (FFF beam for localized prostate cancer based on physical indices

Directory of Open Access Journals (Sweden)

Birendra Kumar Rout

2014-12-01

Full Text Available Purpose: To identify the continual diversity between flattening photon beam (FB and Flattening Filter Free (FFF photon beams for localized prostate cancer; and to determine potential benefits and drawbacks of using unflattened beam for this type of treatment.Methods: Eight prostate cases including seminal vesicles selected for this study. The primary planning target volume (PTVP and boost planning target volume (PTVB were contoured. The total prescription dose was 78 Gy (56 Gy to PTVP and an additional 22 Gy to PTVB. For all cases, treatment plans using 6MV with FB and FFF beams with identical dose-volume constraints, arc angles and number of arcs were developed. The dose volume histograms for both techniques were compared for primary target volume and critical structures.Results: A low Sigma index (FFF: 1.65 + 0.361; FB: 1.725 + 0.39 indicating improved dose homogeneity in FFF beam. Conformity index (FFF: 0.994 + 0.01; FB: 0.993 + 0.01 is comparable for both techniques. Minimal difference of Organ at risk mean dose was observed. Normal tissue integral dose in FB plan resulted 1.5% lower than FFF plan. All the plans displayed significant increase (1.18 times for PTVP and 1.11 for PTBB in the average number of necessary MU with FFF beam.Conclusion: Diversity between FB and FFF beam plans were found. FFF beam accelerator has been utilized to develop clinically acceptable Rapid Arc treatment plans for prostate cancer with 6 MV.---------------------------------Cite this article as: Rout BK, Muralidhar KR, Ali M, Shekar MC, Kumar A. Dosimetric study of RapidArc plans with flattened beam (FB and flattening filter-free (FFF beam for localized prostate cancer based on physical indices. Int J Cancer Ther Oncol 2014; 2(4:02046.  DOI: 10.14319/ijcto.0204.6

Effective atomic numbers and electron density of dosimetric material

Directory of Open Access Journals (Sweden)

Kaginelli S

2009-01-01

Full Text Available A novel method for determination of mass attenuation coefficient of x-rays employing NaI (Tl detector system and radioactive sources is described.in this paper. A rigid geometry arrangement and gating of the spectrometer at FWHM position and selection of absorber foils are all done following detailed investigation, to minimize the effect of small angle scattering and multiple scattering on the mass attenuation coefficient, m/r, value. Firstly, for standardization purposes the mass attenuation coefficients of elemental foils such as Aluminum, Copper, Molybdenum, Tantalum and Lead are measured and then, this method is utilized for dosimetric interested material (sulfates. The experimental mass attenuation coefficient values are compared with the theoretical values to find good agreement between the theory and experiment within one to two per cent. The effective atomic numbers of the biological substitute material are calculated by sum rule and from the graph. The electron density of dosimetric material is calculated using the effective atomic number. The study has discussed in detail the attenuation coefficient, effective atomic number and electron density of dosimetric material/biological substitutes.

Technological advances in radiotherapy of rectal cancer

DEFF Research Database (Denmark)

Appelt, Ane L; Sebag-Montefiore, David

2016-01-01

PURPOSE OF REVIEW: This review summarizes the available evidence for the use of modern radiotherapy techniques for chemoradiotherapy for rectal cancer, with specific focus on intensity-modulated radiotherapy (IMRT) and volumetric arc therapy (VMAT) techniques. RECENT FINDINGS: The dosimetric...

Dosimetric system for measurement of radioactive contaminations

International Nuclear Information System (INIS)

Litynski, Z.; Pienkos, J.P.; Witkowski, J.; Zadrozny, S.

1985-01-01

A dosimetric system for personnel dosimetry and monitoring measuring a contamination without time delay and dead time is described. The system ensures many-point measurement and minimalization of background radiation influence. 1 fig. (A.S.)

Dosimetric analysis of radiation sources to use in dermatological lesions

International Nuclear Information System (INIS)

Tada, Ariane

2010-01-01

Skin lesions undergoing therapy with radiation sources may have different patterns of malignancy. Malignant lesions or cancer most commonly found in radiotherapy services are carcinomas. Radiation therapy in skin lesions is performed with low penetration beams and orthovoltage X-rays, electron beams and radioactive sources ( 192 Ir, 198 Au, e 90 Sr) arranged on a surface mold or in metal applicator. This study aims to analyze the therapeutic radiation dose profile produced by radiation sources used in skin lesions radiotherapy procedures. Experimental measurements for the analysis of dosimetric radiation sources were compared with calculations obtained from a computer system based on the Monte Carlo Method. Computational results had a good agreement with the experimental measurements. Experimental measurements and computational results by the MCNP4C code have been used to validate the calculations obtained by MCNP code and to provide a reliable medical application for each clinical case. (author)

Dosimetry through the Secondary Laboratory of Dosimetric Calibration of Mexico

International Nuclear Information System (INIS)

Tovar M, V.M.; Alvarez R, J.T.; Medina O, V.P.; Vergara M, F.; Anaya M, R.; Cejudo A, J.; Salinas L, B.

2004-01-01

In the beginnings of the sixty years an urgent necessity is presented mainly in the developing countries, of improving in important form the accuracy in the dosimetry of external faces in therapy of radiations (radiotherapy centers), mainly in the calibration of c linical dosemeters . In 1976 the International Atomic Energy Agency, (IAEA), and the World Health Organization, (WHO), they carried out a mutual agreement with regard to the establishment and operation of a net of Secondary Patron Laboratories of Dosimetry, (LSCD). The necessity to establish measure patterns in the field of the dosimetry of the ionizing radiations, is necessary, to have an accuracy but high in the dosimetry of the radiation beams in therapy which is highly dependent of the dose given to the tumor of those patient with cancer. Similar levels of accuracy are required in protection measures to the radiation with an acceptable smaller accuracy, however, when the personal dosemeters are used to determine the doses received by the individuals under work conditions, such mensurations in therapy of radiations and radiological protection will have traceability through a chain of comparisons to primary or national patterns. The traceability is necessary to assure the accuracy and acceptability of the dosimetric measures, as well as, the legal and economic implications. The traceability is also necessary in the dosimetry of high dose like in the sterilization of different products. The main function of the LSCD is to provide a service in metrology of ionizing radiations, maintaining the secondary or national patterns, which have a traceability to the International System of measures, which is based for if same in the comparison of patterns in the Primary Laboratories of Dosimetry (LPD) under the auspice of the International Office of Weights and Measure (BIPM). The secondary and national patterns in the LSCD constitute in Mexico, the national patterns of the magnitudes in the dosimetry of the

Dosimetric properties of a radiochromic gel detector for diagnostic X-rays

International Nuclear Information System (INIS)

Bero, M.A.

2007-01-01

The gel dosimetry method was found to be capable of addressing complicated issues related to dose measurements particularly in modern sophisticated radiotherapy applications. The Ferrous-sulphate Xylenol-orange and Gelatin (FXG) radiochromic gel dosemeter is one of the systems used for such applications. Some chemical dosemeters show different responses for low- and medium-energy X-rays in comparison with high-energy γ-photons. The energy and dose rate dependence of the FXG dose response was examined. In addition to the detector response, other important dosimetric properties of the system were investigated for different X-ray beam qualities with tube voltages in the range 100-300 kV. An orthovoltage X-ray therapy unit was used to irradiate standard sized samples of FXG from different batches for radiation doses in the range 0-20 Gy

Improvement in the dosimetric CaSO4: Dy obtention method

International Nuclear Information System (INIS)

Campos, L.L.; Frutuoso, P.H.; Souto, V.J.

1989-08-01

With the purpose of saving up in the dosimetric CaSO 4 : Dy production, a new method was developed to obtain single crystals. In this method the nitrogen flux used to carry the acid vapour was substituted by compressed air. It was compared all dosimetric properties of the crystals. There is no alteration in the glow curve. The sensitivity is the same in both cases and the lower detection limit is 3.8 x 10 -8 C.Kg -1 (150 μR) [pt

Can All Centers Plan Intensity-Modulated Radiotherapy (IMRT) Effectively? An External Audit of Dosimetric Comparisons Between Three-Dimensional Conformal Radiotherapy and IMRT for Adjuvant Chemoradiation for Gastric Cancer

International Nuclear Information System (INIS)

Chung, Hans T.; Lee, Brian; Park, Eileen; Lu, Jiade J.; Xia Ping

2008-01-01

Purpose: To compare dosimetric endpoints between three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) at our center with limited IMRT experience, and to perform an external audit of the IMRT plans. Methods and Materials: Ten patients, who received adjuvant chemoradiation for gastric cancer, formed the study cohort. For standardization, the planning target volume (PTV) and organs at risk were recontoured with the assistance of a study protocol radiologic atlas. The cohort was replanned with CMS Xio to generate coplanar 3D-CRT and IMRT plans. All 10 datasets, including volumes but without the plans (i.e., blinded), were transmitted to an experienced center where IMRT plans were designed using Nomos Corvus (IMRT-C) and ADAC Pinnacle (IMRT-P). All IMRT plans were normalized to D95% receiving 45 Gy. Results: Intensity-modulated radiotherapy yielded higher PTV V45 (volume that receives ≥45 Gy) (p < 0.001) than 3D-CRT. No difference in V20 was seen in the right (p = 0.9) and left (p 0.3) kidneys, but the liver mean dose (p < 0.001) was superior with IMRT. For the external audit, IMRT-C (p = 0.002) and IMRT-P (p < 0.001) achieved significantly lower left kidney V20 than IMRT, and IMRT-P (p < 0.001) achieved lower right kidney V20 than IMRT. The IMRT-C (p = 0.003) but not IMRT-P (p = 0.6) had lower liver mean doses than IMRT. Conclusions: At our institution with early IMRT experience, IMRT improved PTV dose coverage and liver doses but not kidney doses. An external audit of IMRT plans showed that an experienced center can yield superior IMRT plans

Dosimetric Comparison of Intensity-Modulated Radiotherapy Plans, With or Without Anterior Myocardial Territory and Left Ventricle as Organs at Risk, in Early-Stage Left-Sided Breast Cancer Patients

International Nuclear Information System (INIS)

Tan Wenyong; Wang Xiaohong; Qiu Dasheng; Liu Dong; Jia Shaohui; Zeng Fanyu; Chen Zhengwang; Li Beihui; Xu Jiaozhen; Wei Lai; Hu Desheng

2011-01-01

Purpose: We evaluated heart sparing using an intensity-modulated radiotherapy (IMRT) plan with the left ventricle (LV) and/or the anterior myocardial territory (AMT) as additional organs at risk (OARs). Methods and Materials: A total of 10 patients with left-sided breast cancer were selected for dosimetric planning. Both lungs, the right breast, heart, LV, and AMT were defined as OARs. We generated one tangential field plan and four IMRT plans for each patient. We examined the dose–volume histogram parameters of the planning target volume and OARs. Results: Compared with the tangential field plan, the mean dose to the heart in the IMRT plans did not show significant differences; however, the dose to the AMT and LV decreased by 18.7–45.4% and 10.8–37.4%, respectively. The maximal dose to the heart decreased by 18.6–35.3%, to the AMT by 22.0–45.1%, and to the LV by 23.5–45.0%, And the relative volumes of the heart (V ≥12 ), AMT (V >11 ) and LV (V >10 ) decreased significantly with different levels, respectively. The volume of the heart, AMT, LV, both lungs, and right breast receiving ≥5 Gy showed a significant increase. Compared with the IMRT (H) plan, the mean dose to the heart, AMT, and LV decreased by 17.5–21.5%, 25.2–29.8%, and 22.8–29.8% and the maximal dose by 13.6–20.6%, 23.1–29.6%, and 17.3–29.1%, respectively. The IMRT plans for both lungs and the right breast showed no significant differences. Conclusions: The IMRT plans with the addition of the AMT and/or LV as OARs considerably increased heart sparing. We recommend including the LV as an additional OAR in such plans.

Deep inspiration breath-hold (DIBH) radiotherapy in left-sided breast cancer. Dosimetrical comparison and clinical feasibility in 20 patients

International Nuclear Information System (INIS)

Hepp, Rodrigo; Ammerpohl, Mark; Morgenstern, Christina; Erichsen, Patricia; Nielinger, Lisa; Abdallah, Abdallah; Galalae, Razvan

2015-01-01

Adjuvant radiotherapy after breast-conserving surgery (BCS) for breast cancer (BC) is a well-established indication. The risk of ischaemic heart disease after radiotherapy for BC increases linearly with the heart mean dose with no apparent threshold. Radiotherapy to the left breast in deep inspiration breath-hold (DIBH) reduces the dose to the heart. A new linac system with an integrated surface scanner (SS) for DIBH treatments was recently installed in our department. We tested it for potential benefits, safety, patients' acceptance/compliance and associated additional workload. Twenty consecutive patients following BCS for breast carcinoma of the left side were enrolled in our institutional DIBH protocol. We compared dose to the heart and ipsilateral lung (IL) between plans in DIBH and free breathing (FB) using standard defined parameters: mean dose, maximal dose to a volume of 2 cm 3 (D 2 cm 3 ), volume receiving ≥ 5 Gy (V 5 ), 10 Gy (V 10 ), 15 Gy (V 15 ) and 20 Gy (V 20 ). Comparison of median calculated dose values was performed using a two-tailed Wilcoxon signed rank test. DIBH was associated with a statistically significant reduction (p < 0.001) in all studied parameters for the heart and the IL. In 16 of 20 patients the heart D 2 cm 3 was less than 42 Gy in DIBH. In FB the heart D 2 cm 3 was ≥ 42 Gy in 17 of 20 patients. The median daily treatment time was 9 min. Radiotherapy of the left breast in DIBH using a SS could easily be incorporated into daily routine and is associated with significant dose reduction to the heart and IL. (orig.) [de

Dosimetric comparison of stopping power calibration with dual-energy CT and single-energy CT in proton therapy treatment planning

Energy Technology Data Exchange (ETDEWEB)

Zhu, Jiahua [Department of Physics, University of Adelaide, Adelaide, SA 5005 (Australia); Penfold, Scott N., E-mail: scott.penfold@adelaide.edu.au [Department of Physics, University of Adelaide, Adelaide, SA 5005, Australia and Department of Medical Physics, Royal Adelaide Hospital, Adelaide, SA 5000 (Australia)

2016-06-15

Purpose: The accuracy of proton dose calculation is dependent on the ability to correctly characterize patient tissues with medical imaging. The most common method is to correlate computed tomography (CT) numbers obtained via single-energy CT (SECT) with proton stopping power ratio (SPR). CT numbers, however, cannot discriminate between a change in mass density and change in chemical composition of patient tissues. This limitation can have consequences on SPR calibration accuracy. Dual-energy CT (DECT) is receiving increasing interest as an alternative imaging modality for proton therapy treatment planning due to its ability to discriminate between changes in patient density and chemical composition. In the current work we use a phantom of known composition to demonstrate the dosimetric advantages of proton therapy treatment planning with DECT over SECT. Methods: A phantom of known composition was scanned with a clinical SECT radiotherapy CT-simulator. The phantom was rescanned at a lower X-ray tube potential to generate a complimentary DECT image set. A set of reference materials similar in composition to the phantom was used to perform a stoichiometric calibration of SECT CT number to proton SPRs. The same set of reference materials was used to perform a DECT stoichiometric calibration based on effective atomic number. The known composition of the phantom was used to assess the accuracy of SPR calibration with SECT and DECT. Intensity modulated proton therapy (IMPT) treatment plans were generated with the SECT and DECT image sets to assess the dosimetric effect of the imaging modality. Isodose difference maps and root mean square (RMS) error calculations were used to assess dose calculation accuracy. Results: SPR calculation accuracy was found to be superior, on average, with DECT relative to SECT. Maximum errors of 12.8% and 2.2% were found for SECT and DECT, respectively. Qualitative examination of dose difference maps clearly showed the dosimetric advantages

The dilemma of parotid gland and pharyngeal constrictor muscles preservation—Is daily online image guidance required? A dosimetric analysis

Energy Technology Data Exchange (ETDEWEB)

Duffy, Olivia; Forde, Elizabeth; Leech, Michelle, E-mail: leechm@tcd.ie

2017-04-01

With margin reduction common in head and neck radiotherapy, it is critical that the dosimetric effects of setup deviations are quantified. With past studies focusing on the quantification of positional and volumetric changes of organs at risk (OARs), this study aimed to measure the dose delivered to these the parotid gland (PG) and pharyngeal constrictor muscles (PCMs) using cone beam computed tomography (CBCT). Furthermore, this investigation sought to establish a potential time trend of change in dose delivered to target volumes secondary to ascertaining the need for daily image guidance (IG) to reduce the dose burden to these important OARs. Intensity modulated radiotherapy (IMRT) plans for 5 locally advanced head and neck patients' plans were created and mapped to weekly CBCTs. Each plan was recalculated without heterogeneity correction allowing for dosimetric comparison. Dosimetric endpoints recorded to assess the effect of positional variation were as per ICRU 83 and included D{sub 95} and D{sub 98} for the target volumes, mean dose (MD) and V{sub 30} {sub Gy} for the PGs, and V{sub 50} {sub Gy} and MD for the PCMs. Results were deemed statistically significant if p < 0.05. No significant time trends were established for these OARs. A significant decrease in V{sub 50} {sub Gy} was observed for all PCMs (p < 0.001) on all CBCTs relative to the original plan. Regarding target volumes, a highly significant decrease in MD (MD = 20 Gy, CI: −20.310 to −19.820) in D{sub 98} of the high-dose planning target volume (PTV [70 Gy]; PTVD{sub 98%} = 70 Gy) for case 3 was found (p ≤ 0.001). A nonpredictable, yet significant dosimetric effect was found. A clinically acceptable balance must be achieved between OAR dosimetry and target coverage as can be achieved by frequent IG.

Dosimetric comparison between CT and X-ray simulation of radiotherapy for lung cancer

International Nuclear Information System (INIS)

Kali Ayguli, Zhang Jinrong; Wang Juwu; Ge Feng; Wang Haifeng; Xu Suling

2007-01-01

Objective: To compare radiotherapy plan of conventional X-ray simulation with CT simulation by 3D-TPS for lung cancer. Methods: Thirty-three patients were allotted to receive both conventional X-ray simulation and CT simulation in the same treatment position. 3D-TPS was used to design 4-field conventional plan of X-ray simulation (RT), 4-field two dimensional plan(2D)and three dimensional conformal radiation plan(3DCRT) of CT simulation for all patients. The total dose was 50 Gy. Dose volume histogram(DVH) was applied to evaluate the difference of target coverage, dose distribution and normal tissue protection among the three plans. Results: 3DCRT and 2D based on CT simulation were superior to RT in the target coverage, target conformity index (TCI) and target homogeneity (TH) (P 20 , V 30 and mean lung dose were similar among 3DCRT, 2D and RT plans. Moreover, the maximum doses of spinal cord were significantly different among the three plans. No statistical differences of doses to 30% of the heart and esophagus volume among the three plans were observed. Conclusions: There is significantly better tumour volume coverage in CT simulation when compared with X-ray conventional simulation. Target volume delineation by CT simulation is improved significantly. The dose distribution is improved by using three dimensional treatment planning system. 3DCRT plan is superior to 2D plans in target conformity index and target homogeneity. Doses delivered to organs surrounding the target such as lung and heart were reduced significantly in 3DCRT. (authors)

Dosimetric impact of interfraction catheter movement and organ motion on MRI/CT guided HDR interstitial brachytherapy for gynecologic cancer

International Nuclear Information System (INIS)

Rey, Felipe; Chang, Chang; Mesina, Carmen; Dixit, Nayha; Kevin Teo, Boon-Keng; Lin, Lilie L.

2013-01-01

Purpose: To determine the dosimetric impact of catheter movement for MRI/CT image guided high dose rate (HDR) interstitial brachytherapy (ISBT) for gynecologic cancers. Materials and methods: Ten patients were treated with HDR ISBT. The CTV and organs at risk were contoured using a postimplant MRI and CT. 5 fractions were delivered twice daily on 3 consecutive days. The first fraction was delivered on day 1 (d1), fraction 2–3 on d2 and fraction 4–5 on d3. MRI/CT was acquired prior to the second and fourth fractions. Four scenarios were modeled. (1) The d1 plan was applied to the d2 and d3 CT, using the updated catheter positions. (2) Replanning was performed for d2 and d3. (3) We applied the dwell positions/times from the d2 replan over the d3 CT and compared with a d3 CT replan. (4) Based on daily MRI, target volumes were recontoured and replanned. Dosimetry was analyzed for each plan and compared to the d1 dose distribution. Results: (1) When using the d1 plan on the d2 and d3 CT with the updated catheter positions, the mean CTV D90 was reduced from 93.4% on d1 to 89.3% (p = 0.08) on d2 and to 87.7% (p = 0.005) on d3. (2) Replanning on d2 and d3 compensated for catheter movement, mean CTV D90 of 95.4% on d2 and 94.6% (p = 0.36) on d3. (3) When compared to the replan of d2 applied on the d3 CT vs the d3 replan, there was no significant difference in coverage, mean CTV D90 of 90.9% (p = 0.09). (4) Reoptimization based on daily MRI, significantly improved the CTV coverage for each day. The mean D2 cc for the rectum was significantly higher with model 1 vs model 3 59.1 ± 4.7 vs 60.9 ± 4.8 (p = 0.04) Gy EQD2. There were no significant differences in D2 cc of bladder and sigmoid between models. Conclusions: Interfraction dosimetric changes significantly decreased the CTV coverage of the third day. Rather than replanning on each day, replanning on the day 2 CT before the second or third fraction would give an optimal solution that would compensate for

The features of radiation induced lung fibrosis related with dosimetric parameters

International Nuclear Information System (INIS)

Oh, Young-Taek; Noh, O Kyu; Jang, Hyunsoo; Chun, Mison; Park, Kyung Joo; Park, Kwang Joo; Kim, Mi-Hwa; Park, Hae-Jin

2012-01-01

Background and purpose: Radiation induced lung fibrosis (RILF) is a major complication after lung irradiation and is very important for long term quality of life and could result in fatal respiratory insufficiency. However, there has been little information on dosimetric parameters for radiotherapy planning in the aspect of RILF. The features of RILF related with dosimetric parameters were evaluated. Methods and materials: Forty-eight patients with non-small cell lung carcinoma who underwent post-operative radiation therapy (PORT) without adjuvant chemotherapy were analyzed. The degree of lung fibrosis was estimated by fibrosis volume and the dosimetric parameters were calculated from the plan of 3-dimensional conformal radiotherapy. Results: The fibrosis volume and V-dose as dosimetric parameters showed significant correlation and the correlation coefficient ranged from 0.602 to 0.683 (P < 0.01). The degree of the correlation line was steeper as the dose increase and threshold dose was not found. Mean lung dose (MLD) showed strong correlation with fibrosis volume (correlation coefficient = 0.726, P < 0.01). Conclusions: The fibrosis volume is continuously increased with V-dose as the reference dose increases. MLD is useful as a single parameter for comparing rival plans in the aspect of RILF.

Dosimetric response evaluation of tooth enamel for accelerator-based neutron radiation

International Nuclear Information System (INIS)

Khan, R.F.H.; Rink, W.J.; Boreham, D.R.

2003-01-01

To study the neutron response of human tooth enamel, a number of experiments with an accelerator-based neutron source have been designed. The neutron beam was produced with the low gamma yield, 7 Li(p,n) 7 Be type thick target, using the 3 MV McMaster K.N. Van de Graaff accelerator. The dosimetry was done using a pre-calibrated snoopy type neutron dosimeter. Neutron irradiation induces a dosimetric signal in the tooth enamel at the same defect site as gamma produced damage with the same g-values (g parallel =1.9973, width 0.4 mT g perpendicular =2.002, width 0.3 mT). The dosimetric signal grows linearly with neutron dose from 6-35 Gy tissue dose. Dosimetric response in two different grain sizes (300-500 μm, and grains <4 mm) has shown increased dosimetric amplitude in the larger grains. Dose build up effect on tooth inside the mouth due to cheek was simulated by placing a 4 mm thick paraffin wax layer between the beam and tooth, but had little effect. These results show that for mean neutron energy of 280 keV, the relative neutron response of the human tooth enamel ranges from 8% to 12% of the equivalent gamma ray response

Biokinetic and dosimetric studies of {sup 188}Re-hyaluronic acid: a new radiopharmaceutical for treatment of hepatocellular carcinoma

Energy Technology Data Exchange (ETDEWEB)

Melendez-Alafort, Laura [Dipartimento di Scienze Farmaceutiche, Universita degli Studi di Padova, 35131 Padua (Italy); Nadali, Anna; Zangoni, Elena [Dipartimento di Scienze Farmaceutiche, Universita degli Studi di Padova, 35131 Padua (Italy); Banzato, Alessandra; Rondina, Maria [Dipartimento di Scienze Oncologiche e Chirurgiche, Universita degli Studi di Padova, Padua (Italy); Rosato, Antonio [Dipartimento di Scienze Oncologiche e Chirurgiche, Universita degli Studi di Padova, Padua (Italy); Istituto Oncologico Veneto, IOV, Padova, Padua (Italy); Mazzi, Ulderico [Dipartimento di Scienze Farmaceutiche, Universita degli Studi di Padova, 35131 Padua (Italy)

2009-08-15

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and has very limited therapeutic options. Recently, it has been found that hyaluronic acid (HA) shows selective binding to CD44 receptors expressed in most cancer histotypes. Since the trend in cancer treatment is the use of targeted radionuclide therapy, the aim of this research was to label HA with rhenium-188 and to evaluate its potential use as a hepatocarcinoma therapeutic radiopharmaceutical. Methods: {sup 188}Re-HA was prepared by a direct labelling method to produce a ReO(O-COO){sub 2}-type coordination complex. {sup 188}Re-HA protein binding and its stability in saline, phosphate buffer, human serum and cysteine solutions were determined. Biokinetic and dosimetric data were estimated in healthy mice (n=60) using the Medical Internal Radiation Dose methodology and mouse model beta-absorbed fractions. To evaluate liver toxicity, alanine aminotranferase (AST) and aspartate aminotranferase (ALT) levels in mice were assessed and the liver maximum tolerated dose (MTD) of {sup 188}Re-HA was determined. Results: A stable complex of {sup 188}Re-HA was obtained with high radiochemical purity (>90%) and low serum protein binding (2%). Biokinetic studies showed a rapid blood clearance (T{sub 1/2}{alpha}=21 min). Four hours after administration, {sup 188}Re-HA was almost totally removed from the blood by the liver due to the selective uptake via HA-specific receptors (73.47{+-}5.11% of the injected dose). The liver MTD in mice was {approx}40 Gy after 7.4 MBq of {sup 188}Re-HA injection. Conclusions: {sup 188}Re-HA complex showed good stability, pharmacokinetic and dosimetric characteristics that confirm its potential as a new agent for HCC radiation therapy.

Dosimetric comparison of helical tomotherapy, intensity-modulated radiation therapy, volumetric-modulated arc therapy, and 3-dimensional conformal therapy for the treatment of T1N0 glottic cancer

International Nuclear Information System (INIS)

Ekici, Kemal; Pepele, Eda K.; Yaprak, Bahaddin; Temelli, Oztun; Eraslan, Aysun F.; Kucuk, Nadir; Altınok, Ayse Y.; Sut, Pelin A.; Alpak, Ozlem D.; Colak, Cemil; Mayadagli, Alpaslan

2016-01-01

Various radiotherapy planning methods for T1N0 laryngeal cancer have been proposed to decrease normal tissue toxicity. We compare helical tomotherapy (HT), linac-based intensity-modulated radiation therapy (IMRT), volumetric-modulated arc therapy (VMAT), and 3-D conformal radiotherapy (3D-CRT) techniques for T1N0 laryngeal cancer. Overall, 10 patients with T1N0 laryngeal cancer were selected and evaluated. Furthermore, 10 radiotherapy treatment plans have been created for all 10 patients, including HT, IMRT, VMAT, and 3D-CRT. IMRT, VMAT, and HT plans vs 3D-CRT plans consistently provided superior planning target volume (PTV) coverage. Similar target coverage was observed between the 3 IMRT modalities. Compared with 3D-CRT, IMRT, HT, and VMAT significantly reduced the mean dose to the carotid arteries. VMAT resulted in the lowest mean dose to the submandibular and thyroid glands. Compared with 3D-CRT, IMRT, HT, and VMAT significantly increased the maximum dose to the spinal cord It was observed that the 3 IMRT modalities studied showed superior target coverage with less variation between each plan in comparison with 3D-CRT. The 3D-CRT plans performed better at the D max of the spinal cord. Clinical investigation is warranted to determine if these treatment approaches would translate into a reduction in radiation therapy–induced toxicities.

Characterization and Management of Interfractional Anatomic Changes for Pancreatic Cancer Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Liu Feng; Erickson, Beth; Peng Cheng [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin (United States); Li, X. Allen, E-mail: ali@mcw.edu [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin (United States)

2012-07-01

Purpose: To quantitatively characterize interfractional anatomic variations in pancreatic cancer radiotherapy (RT) and to study dosimetric advantages for using an online adaptive replanning scheme to account for these variations. Methods and Materials: Targets and organs at risk (OAR) were delineated by autosegmentation based on daily computed tomography (CT) images acquired using a respiration-gated in-room CT during daily image-guided RT (IGRT) for 10 pancreatic cancer patients. Various parameters, including the maximum overlap ratio (MOR) between the volumes based on planning and daily CTs for a structure, while the overlapping volumes were maximized, were used to quantify the interfractional organ deformation with the intrafractional variations largely excluded. An online adaptive RT (ART) was applied to these daily CTs. To evaluate the dosimetric benefits of ART, the dose distributions from the online ART were compared to those from the repositioning in the current standard IGRT practice. Results: The interfractional anatomic variations, particularly the organ deformation, are significant during pancreas irradiation. For the patients studied, the average MORs of all daily CTs were 80.2%, 61.7%, and 72.2% for pancreatic head, duodenum, and stomach, respectively. The online ART leads to improved dosimetric plan with better target coverage and/or OAR sparing than IGRT repositioning. For the patients studied, the mean V{sub 50.4Gy} (volume covered by 50.4 Gy) for the duodenum was reduced from 43.4% for IGRT to 15.6% for the online ART scheme. Conclusions: The online adaptive RT scheme can effectively account for the significant interfractional anatomic variations observed in pancreas irradiation. The dosimetric advantages with the online ART may enable safe dose escalation in radiation therapy for pancreatic cancer.

Characterization and Management of Interfractional Anatomic Changes for Pancreatic Cancer Radiotherapy

International Nuclear Information System (INIS)

Liu Feng; Erickson, Beth; Peng Cheng; Li, X. Allen

2012-01-01

Purpose: To quantitatively characterize interfractional anatomic variations in pancreatic cancer radiotherapy (RT) and to study dosimetric advantages for using an online adaptive replanning scheme to account for these variations. Methods and Materials: Targets and organs at risk (OAR) were delineated by autosegmentation based on daily computed tomography (CT) images acquired using a respiration-gated in-room CT during daily image-guided RT (IGRT) for 10 pancreatic cancer patients. Various parameters, including the maximum overlap ratio (MOR) between the volumes based on planning and daily CTs for a structure, while the overlapping volumes were maximized, were used to quantify the interfractional organ deformation with the intrafractional variations largely excluded. An online adaptive RT (ART) was applied to these daily CTs. To evaluate the dosimetric benefits of ART, the dose distributions from the online ART were compared to those from the repositioning in the current standard IGRT practice. Results: The interfractional anatomic variations, particularly the organ deformation, are significant during pancreas irradiation. For the patients studied, the average MORs of all daily CTs were 80.2%, 61.7%, and 72.2% for pancreatic head, duodenum, and stomach, respectively. The online ART leads to improved dosimetric plan with better target coverage and/or OAR sparing than IGRT repositioning. For the patients studied, the mean V 50.4Gy (volume covered by 50.4 Gy) for the duodenum was reduced from 43.4% for IGRT to 15.6% for the online ART scheme. Conclusions: The online adaptive RT scheme can effectively account for the significant interfractional anatomic variations observed in pancreas irradiation. The dosimetric advantages with the online ART may enable safe dose escalation in radiation therapy for pancreatic cancer.

Computational model for dosimetric purposes in dental procedures

International Nuclear Information System (INIS)

Kawamoto, Renato H.; Campos, Tarcisio R.

2013-01-01

This study aims to develop a computational model for dosimetric purposes the oral region, based on computational tools SISCODES and MCNP-5, to predict deterministic effects and minimize stochastic effects caused by ionizing radiation by radiodiagnosis. Based on a set of digital information provided by computed tomography, three-dimensional voxel model was created, and its tissues represented. The model was exported to the MCNP code. In association with SICODES, we used the Monte Carlo N-Particle Transport Code (MCNP-5) method to play the corresponding interaction of nuclear particles with human tissues statistical process. The study will serve as a source of data for dosimetric studies in the oral region, providing deterministic effect and minimize the stochastic effect of ionizing radiation

Adaptive radiotherapy for head and neck cancer—Dosimetric results from a prospective clinical trial

International Nuclear Information System (INIS)

Schwartz, David L.; Garden, Adam S.; Shah, Shalin J.; Chronowski, Gregory; Sejpal, Samir; Rosenthal, David I.; Chen, Yipei; Zhang, Yongbin; Zhang, Lifei; Wong, Pei-Fong; Garcia, John A.; Kian Ang, K.; Dong, Lei

2013-01-01

Purpose: To conduct a clinical trial evaluating adaptive head and neck radiotherapy (ART). Methods: Patients with locally advanced oropharyngeal cancer were prospectively enrolled. Daily CT-guided setup and deformable image registration permitted mapping of dose to avoidance structures and CTVs. We compared four planning scenarios: (1) original IMRT plan aligned daily to marked isocenter (BB); (2) original plan aligned daily to bone (IGRT); (3) IGRT with one adaptive replan (ART1); and (4) actual treatment received by each study patient (IGRT with one or two adaptive replans, ART2). Results: All 22 study patients underwent one replan (ART1); eight patients had two replans (ART2). ART1 reduced mean dose to contralateral parotid by 0.6 Gy or 2.8% (paired t-test; p = 0.003) and ipsilateral parotid by 1.3 Gy (3.9%) (p = 0.002) over the IGRT alone. ART2 further reduced the mean contralateral parotid dose by 0.8 Gy or 3.8% (p = 0.026) and ipsilateral parotid by 4.1 Gy or 9% (p = 0.001). ART significantly reduced integral body dose. Conclusions: This pilot trial suggests that head and neck ART dosimetrically outperforms IMRT. IGRT that leverages conventional PTV margins does not improve dosimetry. One properly timed replan delivers the majority of achievable dosimetric improvement. The clinical impact of ART must be confirmed by future trials

Dosimetric effect on pediatric conformal treatment plans using dynamic jaw with Tomotherapy HDA

Energy Technology Data Exchange (ETDEWEB)

Han, Eun Young, E-mail: eyhan@uams.edu [Department of Radiation Oncology, University of Arkansas Medical Sciences, Little Rock, AR (United States); Kim, Dong-Wook [Department of Radiation Oncology, Kyung Hee University Hospital, Seoul (Korea, Republic of); Zhang, Xin; Penagaricano, Jose; Liang, Xiaoying; Hardee, Matthew; Morrill, Steve; Ratanatharathorn, Vaneerat [Department of Radiation Oncology, University of Arkansas Medical Sciences, Little Rock, AR (United States)

2015-10-01

It is important to minimize the radiation dose delivered to healthy tissues in pediatric cancer treatment because of the risk of secondary malignancies. Tomotherapy HDA provides a dynamic jaw (DJ) delivery mode that creates a sharper penumbra at the craniocaudal ends of a target in addition to a fixed jaw (FJ) delivery mode. The purpose of this study was to evaluate its dosimetric effect on the pediatric cancer cases. We included 6 pediatric cases in this study. The dose profiles and plan statistics—target dose conformity, uniformity, organ-at-risk (OAR) mean dose, beam-on time, and integral dose—were compared for each case. Consequently, the target dose coverage and uniformity were similar for different jaw settings. The OAR dose sparing depended on its relative location to the target and disease sites. For example, in the head and neck cancer cases, the brain stem dose using DJ 2.5 was reduced by more than two-fold (2.4 Gy vs. 6.3 Gy) than that obtained with FJ 2.5. The integral dose with DJ 2.5 decreased by more than 9% compared with that with FJ 2.5. Thus, using dynamic jaw in pediatric cases could be critical to reduce a probability of a secondary malignancy.

Dosimetric essay in dental radiology; Experiencia dosimetrica en radiologia odontologica

Energy Technology Data Exchange (ETDEWEB)

Lopez Salaberry, M [Ministerio de Industria, Energia y Mineria, Montevideo (Uruguay). Direccion Nacional de Tecnologia Nuclear; Dato Carfagna, A; Rodriguez Dorgia, R [Universidad de la Republica, Facultad de Odontologia , Montevideo (Uruguay)

1999-12-31

A neck study was observated in the tiroids glands,laryngeal zone, sensitive organs for the ionizing radiation for increase dental xray exams. Was selected 29th patients with radiography prescription complete (in the Odontology Faculty Clinics Uruguaian). It took radiographies with and without tiroids necklace and apron lead using dosemeters. Dosimetric studies had demonstrated good dose between patients. For measuring the radiation dose have been used TLD thermoluminescence dosimetric and Harshaw 6600 for read it. The thyroids necklace use and odontology postgrading for training course for dentistry was the two recommendations advised

Dosimetric comparison of different multileaf collimator leaves in treatment planning of intensity-modulated radiotherapy for cervical cancer

International Nuclear Information System (INIS)

Wang, Shichao; Ai, Ping; Xie, Li; Xu, Qingfeng; Bai, Sen; Lu, You; Li, Ping; Chen, Nianyong

2013-01-01

To study the effect of multileaf collimator (MLC) leaf widths (standard MLC [sMLC] width of 10 mm and micro-MLC [mMLC] width of 4 mm) on intensity-modulated radiotherapy (IMRT) for cervical cancer. Between January 2010 and August 2010, a retrospective analysis was conducted on 12 patients with cervical cancer. The treatment plans for all patients were generated with the same machine setup parameters and optimization methods in a treatment planning system (TPS) based on 2 commercial Elekta MLC devices. The dose distribution for the planning tumor volume (PTV), the dose sparing for organs at risk (OARs), the monitor units (MUs), and the number of IMRT segments were evaluated. For the delivery efficiency, the MUs were significantly higher in the sMLC-IMRT plan than in the mMLC-IMRT plan (802 ± 56.9 vs 702 ± 56.7; p 0.05). For the planning quality, the conformity index (CI) between the 2 paired IMRT plans with the mMLC and the sMLC did not differ significantly (average: 0.817 ± 0.024 vs 0.810 ± 0.028; p > 0.05). The differences of the homogeneity index (HI) between the 2 paired plans were statistically significant (average: 1.122 ± 0.010 vs 1.132 ± 0.014; p 10 , V 20 , V 30 , and V 40 , percentage of contoured OAR volumes receiving 10, 20, 30, and 40 Gy, respectively, and the mean dose (D mean ) received. The IMRT plans with the mMLC protected the OARs better than the plans with the sMLC. There were significant differences (p 30 and V 40 of the rectum and V 10 , V 20 , V 40 , and D mean of the bladder. IMRT plans with the mMLC showed advantages over the plans with the sMLC in dose homogeneity for targets, dose sparing of OARs, and fewer MUs in cervical cancer

Radiometric and dosimetric characteristics of HgI2 detectors

International Nuclear Information System (INIS)

Zaletin, V.M.; Krivozubov, O.V.; Torlin, M.A.; Fomin, V.I.

1988-01-01

The characteristics of HgI 2 detectors in x-ray and gamma detection in applications to radiometric and dosimetric monitoring and as portable instruments for such purposes was considered. Blocks with mosaic and sandwich structures were prepared and tested against each other and, for comparative purposes, against CdTe detectors for relative sensitivities at various gamma-quanta energies. Sensitivity dependencies on gamma radiation energy were plotted for the detector materials and structures as were current dependencies on the dose rate of x rays. Results indicated that the mercury iodide detectors could be used in radiometric and dosimetric measurements at gamma quantum energies up to and in excess of 1000 KeV

Revision of the dosimetric parameters of the CSM11 LDR Cs-137 source.

Science.gov (United States)

Otal, Antonio; Martínez-Fernández, Juan Manuel; Granero, Domingo

2011-03-01

The clinical use of brachytherapy sources requires the existence of dosimetric data with enough of quality for the proper application of treatments in clinical practice. It has been found that the published data for the low dose rate CSM11 Cs-137 source lacks of smoothness in some regions because the data are too noisy. The purpose of this study was to calculate the dosimetric data for this source in order to provide quality dosimetric improvement of the existing dosimetric data of Ballester et al . [1]. In order to obtain the dose rate distributions Monte Carlo simulations were done using the GEANT4 code. A spherical phantom 40 cm in radius with the Cs-137 source located at the centre of the phantom was used. The results from Monte Carlo simulations were applied to derive AAPM Task Group 43 dosimetric parameters: anisotropy function, radial dose function, air kerma strength and dose rate constant. The dose rate constant obtained was 1.094 ± 0.002 cGy h -1 U -1 . The new calculated data agrees within experimental uncertainties with the existing data of Ballester et al . but without the statistical noise of that study. The obtained data presently fulfills all the requirements of the TG-43U1 update and thus it can be used in clinical practice.

Comparison of TG-43 dosimetric parameters of brachytherapy sources obtained by three different versions of MCNP codes.

Science.gov (United States)

Zaker, Neda; Zehtabian, Mehdi; Sina, Sedigheh; Koontz, Craig; Meigooni, Ali S

2016-03-08

Monte Carlo simulations are widely used for calculation of the dosimetric parameters of brachytherapy sources. MCNP4C2, MCNP5, MCNPX, EGS4, EGSnrc, PTRAN, and GEANT4 are among the most commonly used codes in this field. Each of these codes utilizes a cross-sectional library for the purpose of simulating different elements and materials with complex chemical compositions. The accuracies of the final outcomes of these simulations are very sensitive to the accuracies of the cross-sectional libraries. Several investigators have shown that inaccuracies of some of the cross section files have led to errors in 125I and 103Pd parameters. The purpose of this study is to compare the dosimetric parameters of sample brachytherapy sources, calculated with three different versions of the MCNP code - MCNP4C, MCNP5, and MCNPX. In these simulations for each source type, the source and phantom geometries, as well as the number of the photons, were kept identical, thus eliminating the possible uncertainties. The results of these investigations indicate that for low-energy sources such as 125I and 103Pd there are discrepancies in gL(r) values. Discrepancies up to 21.7% and 28% are observed between MCNP4C and other codes at a distance of 6 cm for 103Pd and 10 cm for 125I from the source, respectively. However, for higher energy sources, the discrepancies in gL(r) values are less than 1.1% for 192Ir and less than 1.2% for 137Cs between the three codes.

SU-F-T-501: Dosimetric Comparison of Single Arc-Per-Beam and Two Arc-Per-Beam VMAT Optimization in the Monaco Treatment Planning System

Energy Technology Data Exchange (ETDEWEB)

Kalet, A; Cao, N; Meyer, J; Dempsey, C [University of Washington Medical Center, Seattle, WA (United States); Seattle Cancer Care Alliance, Seattle, WA (United States); Richardson, H [Seattle Cancer Care Alliance, Seattle, WA (United States)

2016-06-15

Purpose: The purpose of this study was to evaluate the dosimetric and practical effects of the Monaco treatment planning system “max arcs-per-beam” optimization parameter in pelvic radiotherapy treatments. Methods: A total of 17 previously treated patients were selected for this study with a range of pelvic disease site including prostate(9), bladder(1), uterus(3), rectum(3), and cervix(1). For each patient, two plans were generated, one using a arc-per-beam setting of ‘1’ and another with setting of ‘2’. The setting allows the optimizer to add a gantry direction change, creating multiple arc passes per beam sequence. Volumes and constraints established from the initial clinical treatments were used for planning. All constraints and dose coverage objects were kept the same between plans, and all plans were normalized to 99.7% to ensure 100% of the PTV received 95% of the prescription dose. We evaluated the PTV conformity index, homogeneity index, total monitor units, number of control points, and various dose volume histogram (DVH) points for statistical comparison (alpha=0.05). Results: We found for the 10 complex shaped target volumes (small central volumes with extending bilateral ‘arms’ to cover nodal regions) that the use of 2 arcs-per-beam achieved significantly lower average DVH values for the bladder V20 (p=0.036) and rectum V30 (p=0.001) while still meeting the high dose target constraints. DVH values for the simpler, more spherical PTVs were not found significantly different. Additionally, we found a beam delivery time reduction of approximately 25%. Conclusion: In summary, the dosimetric benefit, while moderate, was improved over a 1 arc-per-beam setting for complex PTVs, and equivalent in other cases. The overall reduced delivery time suggests that the use of multiple arcs-per-beam could lead to reduced patient on table time, increased clinical throughput, and reduced medical physics quality assurance effort.

The impact of body mass index on dosimetric quality in low-dose-rate prostate brachytherapy

Directory of Open Access Journals (Sweden)

Michelle I. Echevarria

2016-11-01

Full Text Available Purpose : Low-dose-rate (LDR brachytherapy has been established as an effective and safe treatment option for men with low and intermediate risk prostate cancer. In this retrospective analysis, we sought to study the effect of body mass index (BMI on post-implant dosimetric quality. Material and methods : After institutional approval, records of patients with non-metastatic prostate cancer treated in Puerto Rico with LDR brachytherapy during 2008-2013 were reviewed. All patients were implanted with 125I seeds to a prescription dose of 145 Gy. Computed tomography (CT based dosimetry was performed 1 month after implant. Patients with at least 1 year of prostate-specific antigen (PSA follow-up were included. Factors predictive of adequate D90 coverage (≥ 140 Gy were compared via the Pearson χ2 or Wilcoxon rank-sum test as appropriate. Results : One-hundred and four patients were included in this study, with 53 (51% patients having a D90 ≥ 140 Gy. The only factor associated with a dosimetric coverage detriment (D90 < 140 Gy was BMI ≥ 25 kg/m2 (p = 0.03. Prostate volume (p = 0.26, initial PSA (p = 0.236, age (p = 0.49, hormone use (p = 0.93, percent of cores positive (p = 0.95, risk group (p = 0.24, tumor stage (p = 0.66, and Gleason score (p = 0.61 did not predict D90. Conclusions : In this study we show that BMI is a significant pre-implant predictor of D90 (< 140 Gy vs. ≥ 140 Gy. Although other studies have reported that prostate volume also affects D90, our study did not find this correlation to be statistically significant, likely because all of our patients had a prostate volume 140 Gy.

Determination of Absorbed Dose Using a Dosimetric Film

International Nuclear Information System (INIS)

Scarlat, F.; Scarisoreanu, A.; Oane, M.; Badita, E.; Mitru, E.

2009-01-01

This paper presents the absorbed dose measurements by means of the irradiated dosimetric reference films. The dose distributions were made by MULTIDATA film densitometer using RTD-4 software, in INFLPR Linear Accelerator Department

Influence of jaw tracking in intensity-modulated and volumetric-modulated arc radiotherapy for head and neck cancers: a dosimetric study

Energy Technology Data Exchange (ETDEWEB)

Mani, Karthick Raj [Research and Development Centre, Bharathiar University, Tamilnadu (India); Upadhayay, Sagar [Radiation Oncology, Kathmandu Cancer Center, Bhaktapur (Nepal); Das, K. J. Maria [Dept. of Radiotherapy, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Uttar Pradesh (India)

2017-03-15

To Study the dosimetric advantage of the Jaw tracking technique in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) for Head and Neck Cancers. We retrospectively selected 10 previously treated head and neck cancer patients stage (T1/T2, N1, M0) in this study. All the patients were planned for IMRT and VMAT with simultaneous integrated boost technique. IMRT and VMAT plans were performed with jaw tracking (JT) and with static jaw (SJ) technique by keeping the same constraints and priorities for a particular patient. Target conformity, dose to the critical structures and low dose volumes were recorded and analyzed for IMRT and VMAT plans with and without JT for all the patients. The conformity index average of all patients followed by standard deviation (x¯x¯ ± σx¯σx¯) of the JT-IMRT, SJ-IMRT, JT-VMAT, and SJ-VMAT were 1.72 ± 0.56, 1.67 ± 0.57, 1.83 ± 0.65, and 1.85 ± 0.64, and homogeneity index were 0.059 ± 0.05, 0.064 ± 0.05, 0.064 ± 0.04, and 0.064 ± 0.05. JT-IMRT shows significant mean reduction in right parotid and left parotid shows of 7.64% (p < 0.001) and 7.45% (p < 0.001) compare to SJ-IMRT. JT-IMRT plans also shows considerable dose reduction to thyroid, inferior constrictors, spinal cord and brainstem compared to the SJ-IMRT plans. Significant dose reductions were observed for critical structure in the JT-IMRT compared to SJ-IMRT technique. In JT-VMAT plans dose reduction to the critical structure were not significant compared to the SJ-IMRT due to relatively lesser monitor units.

Cancer Drugs: An International Comparison of Postlicensing Price Inflation.

Science.gov (United States)

Savage, Philip; Mahmoud, Sarah; Patel, Yogin; Kantarjian, Hagop

2017-06-01

The cost of cancer drugs forms a rising proportion of health care budgets worldwide. A number of studies have examined international comparisons of initial cost, but there is little work on postlicensing price increases. To examine this, we compared cancer drug prices at initial sale and subsequent price inflation in the United States and United Kingdom and also reviewed relevant price control mechanisms. The 10 top-selling cancer drugs were selected, and their prices at initial launch and in 2015 were compared. Standard nondiscounted prices were obtained from the relevant annual copies of the RED BOOK and the British National Formulary. At initial marketing, prices were on average 42% higher in the United States than in the United Kingdom. After licensing in the United States, all 10 drugs had price rises averaging an overall annual 8.8% (range, 1.4% to 24.1%) increase. In comparison, in the United Kingdom, six drugs had unchanged prices, two had decreased prices, and two had modest price increases. The overall annual increase in the United Kingdom was 0.24%. Cancer drug prices are rising substantially, both at their initial marketing price and, in the United States, at postlicensing prices. In the United Kingdom, the Pharmaceutical Price Regulation Scheme, an agreement between the government and the pharmaceutical industry, controls health care costs while allowing a return on investment and funds for research. The increasing costs of cancer drugs are approaching the limits of sustainability, and a similar government-industry agreement may allow stability for both health care provision and the pharmaceutical industry in the United States.

Dosimetric Effects of Air Pockets Around High-Dose Rate Brachytherapy Vaginal Cylinders

International Nuclear Information System (INIS)

Richardson, Susan; Palaniswaamy, Geethpriya; Grigsby, Perry W.

2010-01-01

Purpose: Most physicians use a single-channel vaginal cylinder for postoperative endometrial cancer brachytherapy. Recent published data have identified air pockets between the vaginal cylinders and the vaginal mucosa. The purpose of this research was to evaluate the incidence, size, and dosimetric effects of these air pockets. Methods and Materials: 25 patients receiving postoperative vaginal cuff brachytherapy with a high-dose rate vaginal cylinders were enrolled in this prospective data collection study. Patients were treated with 6 fractions of 200 to 400 cGy per fraction prescribed at 5 mm depth. Computed tomography simulation for brachytherapy treatment planning was performed for each fraction. The quantity, volume, and dosimetric impact of the air pockets surrounding the cylinder were quantified. Results: In 25 patients, a total of 90 air pockets were present in 150 procedures (60%). Five patients had no air pockets present during any of their treatments. The average number of air pockets per patient was 3.6, with the average total air pocket volume being 0.34 cm 3 (range, 0.01-1.32 cm 3 ). The average dose reduction to the vaginal mucosa at the air pocket was 27% (range, 9-58%). Ten patients had no air pockets on their first fraction but air pockets occurred in subsequent fractions. Conclusion: Air pockets between high-dose rate vaginal cylinder applicators and the vaginal mucosa are present in the majority of fractions of therapy, and their presence varies from patient to patient and fraction to fraction. The existence of air pockets results in reduced radiation dose to the vaginal mucosa.

Internal dosimetric evaluation due to uranium aerosols

International Nuclear Information System (INIS)

Garcia Aguilar Juan; Delgado Avila Gustavo

1991-01-01

The present work has like object to carry out the internal dosimetric evaluation to the occupationally exposed personnel, due to the inhalation of aerosols of natural uranium and enriched in the pilot plant of nuclear fuel production of the National Institute of Nuclear Research

SU-C-BRB-06: Dosimetric Impact of Breast Contour Reconstruction Errors in GammaPod Stereotactic Radiotherapy

International Nuclear Information System (INIS)

Niu, Y; Becker, S; Mutaf, Y; Yu, C

2016-01-01

Purpose: The first GammaPod™ unit, a dedicated prone stereotactic treatment device for early stage breast cancer, has been installed and commissioned at University of Maryland School of Medicine. The objective of this study was to investigate potential dosimetric impact of inaccurate breast contour. Methods: In GammaPod treatments, patient’s beast is immobilized by a breast cup device (BCID) throughout the entire same-day imaging and treatment procedure. 28 different BICD sizes are available to accommodate patients with varying breast sizes. A mild suction helps breast tissue to conform to the shape of the cup with selected size. In treatment planning, dose calculation utilizes previously calculated dose distributions for available cup geometry rather than the breast shape from CT image. Patient CT images with breast cups indicate minor geometric discrepancy between the matched shape of the cup and the breast contour, i.e., the contour size is larger or smaller. In order to investigate the dosimetric impact of these discrepancies, we simulated such discrepancies and reassessed the dose to target as well as skin. Results: In vicinity of skin, hot/cold spots were found when matched cup size was smaller/larger than patient’s breast after comparing the corrected dose profiles from Monte Carlo simulation with the planned dose from TPS. The overdosing/underdosing of target could yield point dose differences as large as 5% due to these setup errors (D95 changes within 2.5%). Maximal skin dose was overestimated/underestimated up to 25%/45% when matched cup size was larger/smaller than real breast contour. Conclusion: The dosimetric evaluation suggests substantial underdosing/overdosing with inaccurate cup geometry during planning, which is acceptable for current clinical trial. Further studies are needed to evaluate such impact to treating small volume close to skin.

SU-C-BRB-06: Dosimetric Impact of Breast Contour Reconstruction Errors in GammaPod Stereotactic Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Niu, Y [Xcision Medical Systems LLC, Columbia, MD (United States); Becker, S; Mutaf, Y [University Maryland School of Medicine, Baltimore, MD (United States); Yu, C [Xcision Medical Systems LLC, Columbia, MD (United States); University Maryland School of Medicine, Baltimore, MD (United States)

2016-06-15

Purpose: The first GammaPod™ unit, a dedicated prone stereotactic treatment device for early stage breast cancer, has been installed and commissioned at University of Maryland School of Medicine. The objective of this study was to investigate potential dosimetric impact of inaccurate breast contour. Methods: In GammaPod treatments, patient’s beast is immobilized by a breast cup device (BCID) throughout the entire same-day imaging and treatment procedure. 28 different BICD sizes are available to accommodate patients with varying breast sizes. A mild suction helps breast tissue to conform to the shape of the cup with selected size. In treatment planning, dose calculation utilizes previously calculated dose distributions for available cup geometry rather than the breast shape from CT image. Patient CT images with breast cups indicate minor geometric discrepancy between the matched shape of the cup and the breast contour, i.e., the contour size is larger or smaller. In order to investigate the dosimetric impact of these discrepancies, we simulated such discrepancies and reassessed the dose to target as well as skin. Results: In vicinity of skin, hot/cold spots were found when matched cup size was smaller/larger than patient’s breast after comparing the corrected dose profiles from Monte Carlo simulation with the planned dose from TPS. The overdosing/underdosing of target could yield point dose differences as large as 5% due to these setup errors (D95 changes within 2.5%). Maximal skin dose was overestimated/underestimated up to 25%/45% when matched cup size was larger/smaller than real breast contour. Conclusion: The dosimetric evaluation suggests substantial underdosing/overdosing with inaccurate cup geometry during planning, which is acceptable for current clinical trial. Further studies are needed to evaluate such impact to treating small volume close to skin.

CaSO4: Dy + Teflon dosimetric pellets for X, beta and gamma radiation detection

International Nuclear Information System (INIS)

Campos, L.L.; Lima, M.F.

1987-08-01

CaSO 4 : Dy + TEFLON dosimetric pellets with high sensitivity and low cost for X, beta and gamma radiation monitoring were studied and developed by the Dosimetric Material Production Laboratory of the Radiological Protection Departament and are disposable for sale. The thickness of the pellets are suitable for X, beta and gamma radiation measurements. The dosimetric properties of these pellets were determined and presented in this work. The results show the usefulness of 0,20mm thick pellets for beta radiation monitoring and 0,80mm thick pellets for x and gamma radiation detection. (Author) [pt

Study of dosimetric systems-ferrous sulfate-ferric sulfate, glass slides and dyed aqueous solutions

International Nuclear Information System (INIS)

Fernandes, L.

1979-01-01

The effect of some variables which can effect the preparation of the ferrous sulfate used as dosimetric solution has been studied. Among these variables the purity of the water used for the preparation of the solution and the presence (or absence) of oxygen in the dosimetric solution were considered. The dose rate distribution according to the transverse and longitudinal sections of the Co 60 irradiator was studied experimentally, using the dosimetric solution, and theoretically, using a computer program (KIFE). The results obtained with the ferrous sulface dosimetric solution were used as reference for the study of the application of EM and MSG glass slide as a dosimetric system. For this purpose the effects of the weakening of the coloration induced in the glass by gamma rays (Co 60 ) and the relationship between the absorbed dose of radiation and the ratio between the variation in absorbation value and the thickness of the glass irradiated, were studied. A study was also made of the use of the dye indicators bromothymol-blue, methyl-orange, Congo-red, neutral-red and p-nitrophenol, in aqueous solution, for radiation dose measurements. The bleaching of each indicator solution, under gamma-radiation (Co 60 ) was studied in oxygen and nitrogen atmospheres.(Author) [pt

Applichation of the sulphate ceric dosimetric in the high doses range

International Nuclear Information System (INIS)

Prieto Miranda, F.

1991-01-01

The ceric-cerous dosimetric system is one of the system more employed in the high dose dosimetry. The spectrophotometric procedure to measure the ceric-concentration is an usual analityc method to determine the absorbed dose. On the other hand, due at increase employ of the irradiation process control. In this paper is realized the ceric-cerous dosimetric calibration in the dose range of 0,6 - 5 kGy and the application in the irradiation process control to differents absorbed dose values

Comparison among therapy planning in volumetric modulated arc for prostate treatments using one or two arches; Comparacao entre planejamentos de terapia em arco volumetrico modulado para tratamentos de prostata utilizando um ou dois arcos

Energy Technology Data Exchange (ETDEWEB)

Silva, Diego C.S.A.; Pavan, Guilherme A.; Nardi, Stela P.; Fairbanks, Leandro R.; Anderson, Ernani; Junior, Juraci P.R.; Junior, Helio A.S., E-mail: diegocunhalves@hotmail.com [Clinicas Oncologicas Integradas/Grupo COI, Rio de Janeiro, RJ (Brazil)

2014-04-15

The study aims to evaluate and compare retrospective planning for prostate cancer using the volumetric modulated arc therapy technique (RapidArc™ - Varian) with one or two arcs. Ten cases of patients with prostate cancer present were replanning with the volume of PTV's between 296.4 cm{sup 3} and 149.6 cm{sup 3} with prescribed dose of 78 Gy. A planning default was created for each case seeking the best result of the distribution dose in the PTV and to minimize the dose to organs at risk, and from this, creates two copies for optimization of one and two arcs. Comparisons of maximum and minimum dose, index of conformity, homogeneity and gradient dose were evaluated in the PTV, the time of the radiation beam and the number of monitor units. The organ at risk were evaluated according to the Radiation Therapy Oncology Group RTOG 0415 and compared in both optimizations. In terms of dosimetric values to organs at risk and PTV were similar, but there was an increase in the number of monitors units and the time of the radiation beam when using the technique with two arcs. Finally the results have showed that use a volumetric modulated arc therapy optimization for prostate cancer it is reaches similar dosimetric goals can be an effective option for radiotherapy department of developing countries with large number of patients. (author)

Impact of post-implant dosimetric parameters on the quality of life of patients treated with low-dose rate brachytherapy for localised prostate cancer: results of a single-institution study

International Nuclear Information System (INIS)

Veccia, Antonello; Caffo, Orazio; Fellin, Giovanni; Mussari, Salvatore; Ziglio, Francesco; Maines, Francesca; Tomio, Luigi; Galligioni, Enzo

2015-01-01

To assess the relationship between dosimetric parameters and the quality of life (QL) outcomes of patients with low-intermediate-risk localised prostate cancer (LPC) treated with low-dose-rate brachytherapy (LDR-BT). We evaluated the participants in two consecutive prospective studies of the QL of patients treated with LDR-BT for LPC. QL was evaluated by means of a patient-completed questionnaire assessing non functional [physical (PHY) and psychological (PSY) well-being, physical autonomy (POW), social relationships (REL)] and functional scales [urinary (URI), rectal (REC), and sexual (SEX) function]; a scale for erectile function (ERE) was included in the second study. Urethra (D10 ≤ 210 Gy) and rectal wall constraints (V100 ≤ 0.5 cc) were used for pre-planning dosimetry and were assessed with post planning computerized tomography one month later for each patient. QL was assessed in 251 LPC patients. Dosimetry did not influence the non-functional scales. As expected, a progressive impairment in sexual and erectile function was reported one month after LDR-BT, and became statistically significant after the third year. Rectal function significantly worsened after LDR-BT, but the differences progressively decreased after the 1-year assessment. Overall urinary function significantly worsened immediately after LDR-BT and then gradually improved over the next three years. Better outcomes were reported for V100 rectal wall volumes of ≤ 0.5 cc and D10 urethra values of ≤ 210 Gy. The findings of this study show that dosimetric parameters influence only functional QL outcomes while non-functional outcomes are only marginally influenced

Preliminary analysis of the risk factors for radiation pneumonitis in patients with non- small-cell lung cancer treated with concurrent erlotinib and thoracic radiotherapy

Directory of Open Access Journals (Sweden)

Zhuang H

2014-05-01

Full Text Available Hongqing Zhuang,* Hailing Hou,* Zhiyong Yuan, Jun Wang, Qingsong Pang, Lujun Zhao, Ping WangDepartment of Radiotherapy, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin Key Laboratory of Cancer Prevention and Therapy, and Tianjin Lung Cancer Center, Tianjin, People's Republic of China*These authors contributed equally to this workPurpose: The aim of this study was to investigate radiation pneumonitis and its associated risk factors in patients with non-small-cell lung cancer treated with concurrent erlotinib and thoracic radiotherapy.Materials and methods: We conducted an analysis of patients with nonoperable stage IIIA–IV non-small-cell lung cancer who were treated with concurrent thoracic radiotherapy and erlotinib (ClinicalTrials.gov identifier: NCT00973310. The Common Terminology Criteria for Adverse Events version 3.0 grading system was applied to evaluate the incidence of radiation pneumonitis. The lung dosimetric parameters were recorded in accordance with the treatment plan, and the study endpoint was radiation pneumonitis at grade 2 or more.Results: Among the 24 selected clinical cases, nine were identified with radiation pneumonitis of grade 2 or above (37.5%. This included four cases with grade 2 (16.7%, two cases with grade 3 (8.3%, and three cases with grade 5 (12.5%. The results showed that the planning target volume was a significant factor affecting the incidence of radiation pneumonitis. All lung dosimetric parameters exhibited statistically significant differences between patients with pneumonitis and patients without pneumonitis. The receiver operating characteristic (ROC curve analysis showed that all lung dosimetric parameters were useful in predicting the incidence of radiation pneumonitis. In addition, the threshold values of V5, V10, V15, V20, V30, and mean lung dose were >4%, >29%, >27%, >22%, >17% and >1,027 cGy, respectively.Conclusion: Special attention

Dosimetric monitoring in Ukraine - Present status and path to the future

International Nuclear Information System (INIS)

Chumak, V.; Boguslavskaya, A.

2007-01-01

Despite wide use of nuclear energy and radiation sources in industry and medicine, there is no centralised dose accounting system in Ukraine; existing dosimetry services operate obsolete manual thermoluminescence dosemeter (TLD) readers and do not meet modern proficiency standards. Currently, dosimetric monitoring is required for ∼42,000 occupationally exposed workers, including 9100 in medicine, 17,000 employees of nuclear power plants and ∼16,000 workers dealing with other sources of occupational exposure. This article presents the plan of elaboration of the United System for monitoring and registration of individual doses which has the aim of harmonisation of individual monitoring in Ukraine through securing methodical unity; scientific and methodological guidance of individual dosimetric control; procurement of common technical policy regarding nomenclature and operation of instrumentation; implementation of quality assurance programmes; development and support of information infrastructure, in particular operation of the national registry of individual doses; training and certification of personnel engaged in the system of individual dosimetric monitoring. (authors)

A new fully integrated X-ray irradiator system for dosimetric research

International Nuclear Information System (INIS)

Richter, D.; Mittelstraß, D.; Kreutzer, S.; Pintaske, R.; Dornich, K.; Fuchs, M.

2016-01-01

A fully housed X-ray irradiator was developed for use within lexsyg or Magnettech desktop equipment. The importance of hardening of the low energy photon radiation is discussed, its performance and feasibility is empirically shown and sustained by basic numerical simulations. Results of the latter for various materials are given for different X-ray source settings in order to provide estimates on the required setup for the irradiation of different geometries and materials. A Si-photodiode provides real-time monitoring of the X-ray-irradiator designed for use in dosimetric dating and other dosimetric application where irradiation of small samples or dosemeters is required. - Highlights: • Bench top X-ray irradiator provides variable dose-rates. • Simulation of low energy photon irradiation and hardening of X-ray. • Al-hardening for the irradiation of H_2O, BeO, Al_2O_3, quartz, feldspars and zircon. • Dosimetric dating equipment for luminescence and ESR.

Investigation of dosimetric characteristics of the high sensitivity LiF:Mg,Cu,P thermoluminescent dosemeter and its applications in diagnostic radiology

International Nuclear Information System (INIS)

Fung, K.K.L.

2000-12-01

evaluate the potential of this T.L. phosphor in the measurement of the very low level doses received by remote critical radiosensitive organs such as the gonads and thyroid eland from scattered X-ray photons. The use of conventional LiF:Mg,Ti T.L. dosemeters for these low level dose measurements is not always feasible. The applications studied in radiological procedures included: dose reduction in lumbar spine radiography utilizing the ''anode heel effect''; gonad dose variation with kV p in chest radiography; foetal dose comparison between computed tomography (CT) and computed radiography (CR) in X-ray pelvimetry; lens dose reduction with bismuth eye shields in CT brain studies; foetal dose assessment of early pregnancy in common high risk radiological examinations. It is anticipated that the unique and favourable dosimetric performance of LiF:Mg,Cu,P T.L. phosphor will be exploited further in measurements of low level dose received by patients and staff in diagnostic radiological procedures such as paediatric X-rays and interventional fluoroscopic examinations. (author)

Investigation of dosimetric characteristics of the high sensitivity LiF:Mg,Cu,P thermoluminescent dosemeter and its applications in diagnostic radiology

Energy Technology Data Exchange (ETDEWEB)

Fung, K.K.L

2000-12-01

evaluate the potential of this T.L. phosphor in the measurement of the very low level doses received by remote critical radiosensitive organs such as the gonads and thyroid eland from scattered X-ray photons. The use of conventional LiF:Mg,Ti T.L. dosemeters for these low level dose measurements is not always feasible. The applications studied in radiological procedures included: dose reduction in lumbar spine radiography utilizing the ''anode heel effect''; gonad dose variation with kV{sub p} in chest radiography; foetal dose comparison between computed tomography (CT) and computed radiography (CR) in X-ray pelvimetry; lens dose reduction with bismuth eye shields in CT brain studies; foetal dose assessment of early pregnancy in common high risk radiological examinations. It is anticipated that the unique and favourable dosimetric performance of LiF:Mg,Cu,P T.L. phosphor will be exploited further in measurements of low level dose received by patients and staff in diagnostic radiological procedures such as paediatric X-rays and interventional fluoroscopic examinations. (author)

ESR dosimetric properties of modern coral reef

Energy Technology Data Exchange (ETDEWEB)

Sharaf, M.A. E-mail: mokhtar_sharaf@yahoo.com; Hassan, Gamal M

2004-06-01

Modern coral reef samples from Egypt were irradiated with {sup 60}Co{gamma}-rays to study radicals for dosimetric materials with electron spin resonance (ESR). The ESR spectrum for the radical species in unirradiated coral is characterized by four signals with spectroscopic splitting factors of g=2.0056, 2.0030, 2.0006 and 1.997. The signal at g=2.0006{+-}0.0005 is ascribed to free rotation CO{sub 2}{sup -} radicals and used as a dosimetric one. The response to {gamma}-ray doses ranging from 5 to 10{sup 3} Gy and the thermal stability has been studied. The number of free radicals per 100 eV (G-value) was found to be 0.45 {+-} 0.1 and 0.9 {+-} 0.18 for coral and alanine, respectively. The lifetime of radicals and the activation energy were estimated from Arrhenius plots to be approximately 8 x 10{sup 5} {+-} 1.6 x 10{sup 5} years, and 1.12 eV, respectively.

A dosimetric comparison of proton and photon therapy in unresectable cancers of the head of pancreas

Energy Technology Data Exchange (ETDEWEB)

Thompson, Reid F.; Zhai, Huifang; Both, Stefan; Metz, James M.; Plastaras, John P.; Ben-Josef, Edgar, E-mail: Edgar.Ben-Josef@uphs.upenn.edu [University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Mayekar, Sonal U. [Thomas Jefferson University, Philadelphia, Pennsylvania 19107 (United States); Apisarnthanarax, Smith [University of Washington, Seattle, Washington 98109 (United States)

2014-08-15

Purpose: Uncontrolled local growth is the cause of death in ∼30% of patients with unresectable pancreatic cancers. The addition of standard-dose radiotherapy to gemcitabine has been shown to confer a modest survival benefit in this population. Radiation dose escalation with three-dimensional planning is not feasible, but high-dose intensity-modulated radiation therapy (IMRT) has been shown to improve local control. Still, dose-escalation remains limited by gastrointestinal toxicity. In this study, the authors investigate the potential use of double scattering (DS) and pencil beam scanning (PBS) proton therapy in limiting dose to critical organs at risk. Methods: The authors compared DS, PBS, and IMRT plans in 13 patients with unresectable cancer of the pancreatic head, paying particular attention to duodenum, small intestine, stomach, liver, kidney, and cord constraints in addition to target volume coverage. All plans were calculated to 5500 cGy in 25 fractions with equivalent constraints and normalized to prescription dose. All statistics were by two-tailed paired t-test. Results: Both DS and PBS decreased stomach, duodenum, and small bowel dose in low-dose regions compared to IMRT (p < 0.01). However, protons yielded increased doses in the mid to high dose regions (e.g., 23.6–53.8 and 34.9–52.4 Gy for duodenum using DS and PBS, respectively; p < 0.05). Protons also increased generalized equivalent uniform dose to duodenum and stomach, however these differences were small (<5% and 10%, respectively; p < 0.01). Doses to other organs-at-risk were within institutional constraints and placed no obvious limitations on treatment planning. Conclusions: Proton therapy does not appear to reduce OAR volumes receiving high dose. Protons are able to reduce the treated volume receiving low-intermediate doses, however the clinical significance of this remains to be determined in future investigations.

Comparison of Cancer Incidence between China and the USA.

Science.gov (United States)

Wang, Yong-Chuan; Wei, Li-Juan; Liu, Jun-Tian; Li, Shi-Xia; Wang, Qing-Sheng

2012-06-01

The incidence of cancer varies around the globe, especially between less-developed and developed regions. The aim of this study is to explore differences in cancer incidence between China and the USA. Data were obtained from the GLOBOCAN 2008 database. Estimated numbers of new cancer cases in the USA were obtained from the American Cancer Society, while the numbers of cases in China, including those in urban and rural areas, were obtained from 36 cancer registries (2003-2005). Cancer incidence for major sites between China and the USA were analyzed. In China, lung cancer was the predominant type of cancer detected in males; in females, breast cancer was the main type of cancer. Gastrointestinal cancers, such as those of the liver, stomach, and esophagus, were more commonly seen in China than in the USA. A significant difference in the incidence of melanoma of the skin was observed between China and the USA. During comparison of differences in the age-standardized rates by world population (ASRWs) of major cancer sites between the two countries, 4 sites in males (i.e., nasopharynx, esophagus, stomach, and liver) and 6 sites in females (i.e., nasopharynx, esophagus, stomach, liver, gallbladder, and cervix uteri) showed higher cancer incidence rates in China than in the USA. Significant differences in cancer incidence sites were found between the two countries. Cancer may be prevented through public education and awareness. Programs to promote cancer prevention in China, especially those of the lung, breast, and gastrointestinal region, must also be implemented.

Theoretical Benefits of Dynamic Collimation in Pencil Beam Scanning Proton Therapy for Brain Tumors: Dosimetric and Radiobiological Metrics

Energy Technology Data Exchange (ETDEWEB)

Moignier, Alexandra, E-mail: alexandra-moignier@uiowa.edu [Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, Iowa (United States); Gelover, Edgar; Wang, Dongxu; Smith, Blake; Flynn, Ryan [Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, Iowa (United States); Kirk, Maura; Lin, Liyong; Solberg, Timothy; Lin, Alexander [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Hyer, Daniel [Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, Iowa (United States)

2016-05-01

Purpose: To quantify the dosimetric benefit of using a dynamic collimation system (DCS) for penumbra reduction during the treatment of brain tumors by pencil beam scanning proton therapy (PBS PT). Methods and Materials: Collimated and uncollimated brain treatment plans were created for 5 patients previously treated with PBS PT and retrospectively enrolled in an institutional review board–approved study. The in-house treatment planning system, RDX, was used to generate the plans because it is capable of modeling both collimated and uncollimated beamlets. The clinically delivered plans were reproduced with uncollimated plans in terms of target coverage and organ at risk (OAR) sparing to ensure a clinically relevant starting point, and collimated plans were generated to improve the OAR sparing while maintaining target coverage. Physical and biological comparison metrics, such as dose distribution conformity, mean and maximum doses, normal tissue complication probability, and risk of secondary brain cancer, were used to evaluate the plans. Results: The DCS systematically improved the dose distribution conformity while preserving the target coverage. The average reduction of the mean dose to the 10-mm ring surrounding the target and the healthy brain were 13.7% (95% confidence interval [CI] 11.6%-15.7%; P<.0001) and 25.1% (95% CI 16.8%-33.4%; P<.001), respectively. This yielded an average reduction of 24.8% (95% CI 0.8%-48.8%; P<.05) for the brain necrosis normal tissue complication probability using the Flickinger model, and 25.1% (95% CI 16.8%-33.4%; P<.001) for the risk of secondary brain cancer. A general improvement of the OAR sparing was also observed. Conclusion: The lateral penumbra reduction afforded by the DCS increases the normal tissue sparing capabilities of PBS PT for brain cancer treatment while preserving target coverage.

Theoretical Benefits of Dynamic Collimation in Pencil Beam Scanning Proton Therapy for Brain Tumors: Dosimetric and Radiobiological Metrics

International Nuclear Information System (INIS)

Moignier, Alexandra; Gelover, Edgar; Wang, Dongxu; Smith, Blake; Flynn, Ryan; Kirk, Maura; Lin, Liyong; Solberg, Timothy; Lin, Alexander; Hyer, Daniel

2016-01-01

Purpose: To quantify the dosimetric benefit of using a dynamic collimation system (DCS) for penumbra reduction during the treatment of brain tumors by pencil beam scanning proton therapy (PBS PT). Methods and Materials: Collimated and uncollimated brain treatment plans were created for 5 patients previously treated with PBS PT and retrospectively enrolled in an institutional review board–approved study. The in-house treatment planning system, RDX, was used to generate the plans because it is capable of modeling both collimated and uncollimated beamlets. The clinically delivered plans were reproduced with uncollimated plans in terms of target coverage and organ at risk (OAR) sparing to ensure a clinically relevant starting point, and collimated plans were generated to improve the OAR sparing while maintaining target coverage. Physical and biological comparison metrics, such as dose distribution conformity, mean and maximum doses, normal tissue complication probability, and risk of secondary brain cancer, were used to evaluate the plans. Results: The DCS systematically improved the dose distribution conformity while preserving the target coverage. The average reduction of the mean dose to the 10-mm ring surrounding the target and the healthy brain were 13.7% (95% confidence interval [CI] 11.6%-15.7%; P<.0001) and 25.1% (95% CI 16.8%-33.4%; P<.001), respectively. This yielded an average reduction of 24.8% (95% CI 0.8%-48.8%; P<.05) for the brain necrosis normal tissue complication probability using the Flickinger model, and 25.1% (95% CI 16.8%-33.4%; P<.001) for the risk of secondary brain cancer. A general improvement of the OAR sparing was also observed. Conclusion: The lateral penumbra reduction afforded by the DCS increases the normal tissue sparing capabilities of PBS PT for brain cancer treatment while preserving target coverage.

Helical Tomotherapy in Children and Adolescents: Dosimetric Comparisons, Opportunities and Issues

Energy Technology Data Exchange (ETDEWEB)

Mascarin, Maurizio, E-mail: mascarin@cro.it [Pediatric Radiotherapy Unit, Centro di Riferimento Oncologico- National Cancer Institute/Via Franco Gallini, 2 33081 Aviano (PN) (Italy); Department of Radiation Therapy, Centro di Riferimento Oncologico- National Cancer Institute/Via Franco Gallini, 2 33081 Aviano (PN) (Italy); Giugliano, Francesca Maria [Pediatric Radiotherapy Unit, Centro di Riferimento Oncologico- National Cancer Institute/Via Franco Gallini, 2 33081 Aviano (PN) (Italy); Seconda Università di Napoli, Napoli 80138 (Italy); Coassin, Elisa [Pediatric Radiotherapy Unit, Centro di Riferimento Oncologico- National Cancer Institute/Via Franco Gallini, 2 33081 Aviano (PN) (Italy); Drigo, Annalisa; Chiovati, Paola; Dassie, Andrea [Department of Radiation Therapy, Centro di Riferimento Oncologico- National Cancer Institute/Via Franco Gallini, 2 33081 Aviano (PN) (Italy); Department of Medical Physics, Centro di Riferimento Oncologico- National Cancer Institute/Via Franco Gallini, 2 33081 Aviano (PN) (Italy); Franchin, Giovanni; Minatel, Emilio; Trovò, Mauro Gaetano [Department of Radiation Therapy, Centro di Riferimento Oncologico- National Cancer Institute/Via Franco Gallini, 2 33081 Aviano (PN) (Italy)

2011-10-25

Helical Tomotherapy (HT) is a highly conformal image-guided radiation technique, introduced into clinical routine in 2006 at the Centro di Riferimento Oncologico Aviano (Italy). With this new technology, intensity-modulated radiotherapy (IMRT) is delivered using a helicoidal method. Here we present our dosimetric experiences using HT in 100 children, adolescents and young adults treated from May 2006 to February 2011. The median age of the patients was 13 years (range 1–24). The most common treated site was the central nervous system (50; of these, 24 were craniospinal irradiations), followed by thorax (22), head and neck (10), abdomen and pelvis (11), and limbs (7). The use of HT was calculated in accordance to the target dose conformation, the target size and shape, the dose to critical organs adjacent to the target, simultaneous treatment of multiple targets, and re-irradiation. HT has demonstrated to improve target volume dose homogeneity and the sparing of critical structures, when compared to 3D Linac-based radiotherapy (RT). In standard cases this technique represented a comparable alternative to IMRT delivered with conventional linear accelerator. In certain cases (e.g., craniospinal and pleural treatments) only HT generated adequate treatment plans with good target volume coverage. However, the gain in target conformality should be balanced with the spread of low-doses to distant areas. This remains an open issue for the potential risk of secondary malignancies (SMNs) and longer follow-up is mandatory.

Radiation exposure due to local fallout from Soviet atmospheric nuclear weapons testing in Kazakhstan: solid cancer mortality in the Semipalatinsk historical cohort, 1960-1999.

Science.gov (United States)

Bauer, Susanne; Gusev, Boris I; Pivina, Ludmila M; Apsalikov, Kazbek N; Grosche, Bernd

2005-10-01

Little information is available on the health effects of exposures to fallout from Soviet nuclear weapons testing and on the combined external and internal environmental exposures that have resulted from these tests. This paper reports the first analysis of the Semipalatinsk historical cohort exposed in the vicinity of the Semipalatinsk nuclear test site, Kazakhstan. The cohort study, which includes 19,545 inhabitants of exposed and comparison villages of the Semipalatinsk region, was set up in the 1960s and comprises 582,750 person-years of follow-up between 1960 and 1999. Cumulative effective radiation dose estimates in this cohort range from 20 mSv to approximately 4 Sv. Rates of mortality and cancer mortality in the exposed group substantially exceeded those of the comparison group. Dose-response analyses within the exposed group confirmed a significant trend with dose for all solid cancers (P sites, a significant trend with dose was observed for lung cancer (P = 0.0001), stomach cancer (P = 0.0050), and female breast cancer (P = 0.0040) as well as for esophagus cancer in women (P = 0.0030). The excess relative risk per sievert for all solid cancers combined was 1.77 (1.35; 2.27) based on the total cohort data, yet a selection bias regarding the comparison group could not be entirely ruled out. The excess relative risk per sievert based on the cohort's exposed group was 0.81 (0.46; 1.33) for all solid cancers combined and thus still exceeds current risk estimates from the Life Span Study. Future epidemiological assessments based on this cohort will benefit from extension of follow-up and ongoing validation of dosimetric data.

Superior sulcus non-small cell lung carcinoma: A comparison of IMRT and 3D-RT dosimetry.

Science.gov (United States)

Truntzer, Pierre; Antoni, Delphine; Santelmo, Nicola; Schumacher, Catherine; Falcoz, Pierre-Emmanuel; Quoix, Elisabeth; Massard, Gilbert; Noël, Georges

2016-01-01

A dosimetric study comparing intensity modulated radiotherapy (IMRT) by TomoTherapy to conformational 3D radiotherapy (3D-RT) in patients with superior sulcus non-small cell lung cancer (NSCLC). IMRT became the main technique in modern radiotherapy. However it was not currently used for lung cancers. Because of the need to increase the dose to control lung cancers but because of the critical organs surrounding the tumors, the gains obtainable with IMRT is not still demonstrated. A dosimetric comparison of the planned target and organs at risk parameters between IMRT and 3D-RT in eight patients who received preoperative or curative intent irradiation. In the patients who received at least 66 Gy, the mean V95% was significantly better with IMRT than 3D-RT (p = 0.043). IMRT delivered a lower D2% compared to 3D-RT (p = 0.043). The IH was significantly better with IMRT (p = 0.043). The lung V 5 Gy and V 13 Gy were significantly higher in IMRT than 3D-RT (p = 0.043), while the maximal dose (D max) to the spinal cord was significantly lower in IMRT (p = 0.043). The brachial plexus D max was significantly lower in IMRT than 3D-RT (p = 0.048). For patients treated with 46 Gy, no significant differences were found. Our study showed that IMRT is relevant for SS-NSCLC. In patients treated with a curative dose, it led to a reduction of the exposure of critical organs, allowing a better dose distribution in the tumor. For the patients treated with a preoperative schedule, our results provide a basis for future controlled trials to improve the histological complete response by increasing the radiation dose.

Comparison of TG‐43 dosimetric parameters of brachytherapy sources obtained by three different versions of MCNP codes

Science.gov (United States)

Zaker, Neda; Sina, Sedigheh; Koontz, Craig; Meigooni1, Ali S.

2016-01-01

Monte Carlo simulations are widely used for calculation of the dosimetric parameters of brachytherapy sources. MCNP4C2, MCNP5, MCNPX, EGS4, EGSnrc, PTRAN, and GEANT4 are among the most commonly used codes in this field. Each of these codes utilizes a cross‐sectional library for the purpose of simulating different elements and materials with complex chemical compositions. The accuracies of the final outcomes of these simulations are very sensitive to the accuracies of the cross‐sectional libraries. Several investigators have shown that inaccuracies of some of the cross section files have led to errors in  125I and  103Pd parameters. The purpose of this study is to compare the dosimetric parameters of sample brachytherapy sources, calculated with three different versions of the MCNP code — MCNP4C, MCNP5, and MCNPX. In these simulations for each source type, the source and phantom geometries, as well as the number of the photons, were kept identical, thus eliminating the possible uncertainties. The results of these investigations indicate that for low‐energy sources such as  125I and  103Pd there are discrepancies in gL(r) values. Discrepancies up to 21.7% and 28% are observed between MCNP4C and other codes at a distance of 6 cm for  103Pd and 10 cm for  125I from the source, respectively. However, for higher energy sources, the discrepancies in gL(r) values are less than 1.1% for  192Ir and less than 1.2% for  137Cs between the three codes. PACS number(s): 87.56.bg PMID:27074460

Comparison of Radiation Treatment Plans for Breast Cancer between 3D Conformal in Prone and Supine Positions in Contrast to VMAT and IMRT Supine Positions

Science.gov (United States)

Bejarano Buele, Ana Isabel

The treatment regimen for breast cancer patients typically involves Whole Breast Irradiation (WBI). The coverage and extent of the radiation treatment is dictated by location of tumor mass, breast tissue distribution, involvement of lymph nodes, and other factors. The current standard treatment approach used at our institution is a 3D tangential beam geometry, which involves two fields irradiating the breast, or a four field beam arrangement covering the whole breast and involved nodes, while decreasing the dose to organs as risk (OARs) such as the lung and heart. The coverage of these targets can be difficult to achieve in patients with unfavorable thoracic geometries, especially in those cases in which the planning target volume (PTV) is extended to the chest wall. It is a well-known fact that exposure of the heart to ionizing radiation has been proved to increase the subsequent rate of ischemic heart disease. In these cases, inverse planned treatments have become a proven alternative to the 3D approach. The goal of this research project is to evaluate the factors that affect our current techniques as well as to adapt the development of inverse modulated techniques for our clinic, in which breast cancer patients are one of the largest populations treated. For this purpose, a dosimetric comparison along with the evaluation of immobilization devices was necessary. Radiation treatment plans were designed and dosimetrically compared for 5 patients in both, supine and prone positions. For 8 patients, VMAT and IMRT plans were created and evaluated in the supine position. Skin flash incorporation for inverse modulated plans required measurement of the surface dose as well as an evaluation of breast volume changes during a treatment course. It was found that prone 3D conformal plans as well as the VMAT and IMRT plans are generally superior in sparing OARs to supine plans with comparable PTV coverage. Prone setup leads to larger shifts in breast volume as well as in

Dosimetric implications of residual seminal vesicle motion in fiducial-guided intensity-modulated radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Stenmark, Matthew H.; Vineberg, Karen; Ten Haken, Randall K.; Hamstra, Daniel A.; Feng, Mary

2012-01-01

To determine whether residual interfraction seminal vesicle (SV) displacement necessitates specific planning target volume (PTV) margins during fiducial-guided intensity modulated radiation therapy (IMRT) of the prostate. A planning computed tomography (CT) scan and 2 subsequent CT scans were prospectively obtained for 20 prostate cancer patients with intraprostatic fiducial markers. After CT registration, SV displacement relative to the prostate was quantified as a function of margin size for both the proximal (1 cm) SV (PSV) and the full SV (FSV). Two IMRT plans were simulated for each patient (prostate + PSV and prostate + FSV) both with a uniform 5-mm PTV margin. Minimum clinical target volume (CTV) dose (D min ) and the volume of SV receiving 95% of the prescription dose (V 95% ) were assessed during treatment and compared with the initial plan. In all cases, SV displacement with respect to the prostate was greater for the FSV compared with the PSV. To ensure at least 95% geometrical coverage of the CTV for 90% of patients, margins of 5 and 8 mm were required for the PSV and FSV, respectively. Dosimetrically, residual SV displacement had minimal impact on PSV coverage compared with FSV coverage. For the PSV D min was ≥95% of the prescribed dose in 90% of patients with an overall mean V 95% of 99.6 ± 0.8%; for the FSV D min was ≥95% of the prescribed dose in only 45% of patients with a mean V 95% of 97.9 ± 2.4%. The SVs move differentially from the prostate and exhibit greater variation with increasing distance from the prostate. For plans targeting just the prostate and PSVs, 5-mm PTV expansions are adequate. However, despite daily localization of the prostate, larger PTV margins are required for cases where the intent is to completely cover the FSV.

SU-F-T-14: Dosimetric Impacts of Various Uncertainties in Cervical Cancer HDR Brachytherapy: Are Conventional Point Doses Good Surrogates for 3D Dosimetry?

Energy Technology Data Exchange (ETDEWEB)

Liang, X; Li, Z [University of Florida Health Proton Therapy Institute, Jacksonville, FL (United States); Zheng, D [University of Nebraska Medical Center, Omaha, NE (United States); Zhang, X; Narayanasamy, G; Morrill, S; Penagaricano, J; Paudel, N [University of Arkansas for Medical Sciences, Little Rock, AR (United States)

2016-06-15

Purpose: In the context of evaluating dosimetric impacts of a variety of uncertainties involved in HDR Tandem-and-Ovoid treatment, to study the correlations between conventional point doses and 3D volumetric doses. Methods: For 5 cervical cancer patients treated with HDR T&O, 150 plans were retrospectively created to study dosimetric impacts of the following uncertainties: (1) inter-fractional applicator displacement between two treatment fractions within a single insertion by applying Fraction#1 plan to Fraction#2 CT; (2) positional dwell error simulated from −5mm to 5mm in 1mm steps; (3) simulated temporal dwell error of 0.05s, 0.1s, 0.5s, and 1s. The original plans were based on point dose prescription, from which the volume covered by the prescription dose was generated as the pseudo target volume to study the 3D target dose effect. OARs were contoured. The point and volumetric dose errors were calculated by taking the differences between original and simulated plans. The correlations between the point and volumetric dose errors were analyzed. Results: For the most clinically relevant positional dwell uncertainty of 1mm, temporal uncertainty of 0.05s, and inter-fractional applicator displacement within the same insertion, the mean target D90 and V100 deviation were within 1%. Among these uncertainties, the applicator displacement showed the largest potential target coverage impact (2.6% on D90) as well as the OAR dose impact (2.5% and 3.4% on bladder D2cc and rectum D2cc). The Spearman correlation analysis shows a correlation coefficient of 0.43 with a p-value of 0.11 between target D90 coverage and H point dose. Conclusion: With the most clinically relevant positional and temporal dwell uncertainties and patient interfractional applicator displacement within the same insertion, the dose error is within clinical acceptable range. The lack of correlation between H point and 3D volumetric dose errors is a motivator for the use of 3D treatment planning in

Determination of Dosimetric Parameters of the Second Model of Pd-103 Seed Manufactured at Agricultural, Medical and Industrial Research School

OpenAIRE

Gholamreza Raisali; Mahdi Sadeghi; Vahideh Ataeinia; Arjang Shahvar; Maryam Ghasemi Ghonchehnazi

2008-01-01

Introduction: The use of low energy isotopes such as  103 Pd in brachytherapy for the treatment of cancers  such as prostate, eye, head, neck, breast and cervix is increasing. In this regard, different models of Pd- 103  seeds  have  been  designed  and  manufactured  at  the  Agricultural,  Medical  and  Industrial  Research  School (AMIRS) of Atomic Energy Organization of Iran. In this research, the dosimetric parameters of  the second model of Pd-103 seed manufactured at AMIRS have been ca...

Geometric factors influencing dosimetric sparing of the parotid glands using IMRT

International Nuclear Information System (INIS)

Hunt, Margie A.; Jackson, Andrew; Narayana, Ashwatha; Lee, Nancy

2006-01-01

Purpose/Objective: To determine the relationship between the parotid volume, parotid-planning target volume (PTV) overlap, and dosimetric sparing of the parotid with intensity-modulated radiation therapy (IMRT). Methods and Materials: Parotid data were collected retrospectively for 51 patients treated with simultaneous boost IMRT. Unresectable patients received 54 or 59.4 Gy to subclinical disease, 70 Gy to gross disease. Patients treated postoperatively received 54, 60, and 66 Gy to low-risk, high-risk, and tumor bed regions. Volume and mean dose of each gland and gland segments outside of and overlapping the PTV were collected. Proximity of each gland to each PTV was recorded. Results: Dosimetric sparing (mean dose ≤26.5 Gy) was achieved in 66 of 71 glands with ≤21% parotid-PTV overlap and 8 of 23 glands with >21% overlap (p = 21%. Median mean dose was 25.9 Gy to glands overlapping PTV 54 or PTV 59 alone and 30.0 Gy to those abutting PTV 7 (p 7 was associated with higher parotid dose, satisfactory sparing was achieved in 24 of 43 ipsilateral glands. Conclusions: Dosimetric sparing of the parotid is feasible when the parotid-PTV overlap is less than approximately 20%. With more overlap, sparing may result in low doses within the overlap region, possibly leading to inadequate PTV coverage. Gland proximity to the high-dose PTV is associated with higher mean dose but does not always preclude dosimetric sparing

Dosimetric characterization of BeO samples in alpha, beta and X radiation beams using luminescent techniques

International Nuclear Information System (INIS)

Groppo, Daniela Piai

2013-01-01

In the medical field, the ionizing radiation is used both for therapeutic and diagnostic purposes, in a wide range of radiation doses. In order to ensure that the objective is achieved in practice, detailed studies of detectors and devices in different types of radiations beams are necessary. In this work a dosimetric characterization of BeO samples was performed using the techniques of thermoluminescence (TL) and optically stimulated luminescence (OSL) by a comparison of their response for alpha, beta and X radiations and the establishment of an appropriated system for use in monitoring of these radiations beams. The main results are: the high sensitivity to beta radiation for both techniques, good reproducibility of TL and OSL response (coefficients of variation lower than 5%), maximum energy dependence of the X radiation of 28% for the TL technique, and only 7% for the OSL technique, within the studied energy range. The dosimetric characteristics obtained in this work show the possibility of applying BeO samples to dosimetry of alpha, beta and X radiations, considering the studied dose ranges, using the TL and OSL techniques. From the results obtained, the samples of BeO showed their potential use for beam dosimetry in diagnostic radiology and radiotherapy. (author)

SU-F-J-128: Dosimetric Impact of Esophagus Motion in Spine Stereotactic Body Radiotherapy

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Yang, J; Wang, X; Zhao, Z; Yang, J; Zhang, Y; Court, L; Li, J; Brown, P; Ghia, A [MD Anderson Cancer Center, Houston, TX (United States)

2016-06-15

Purpose: Acute esophageal toxicity is a common side effect in spine stereotactic body radiotherapy (SBRT). The respiratory motion may alter esophageal position from the planning scan resulting in excessive esophageal dose. Here we assessed the dosimetric impact resulting from the esophageal motion using 4DCT. Methods: Nine patients treated to their thoracic spines in one fraction of 24 Gy were identified for this study. The original plan on a free breathing CT was copied to each phase image of a 4DCT scan, recalculated, scaled, and accumulated to the free breathing CT using deformable image registration. A segment of esophagus was contoured in the vicinity of treatment target. Esophagus dose volume histogram (DVH) was generated for both the original planned dose and the accumulated 4D dose for comparison. In parallel, we performed a chained deformable registration of 4DCT phase images to estimate the motion magnitude of the esophagus in a breathing cycle. We examined the correlation between the motion magnitude and the dosimetric deviation. Results: The esophageal motion mostly exhibited in the superior-inferior direction. The cross-sectional motion was small. Esophagus motion at T1 vertebra level (0.7 mm) is much smaller than that at T11 vertebra level (6.5 mm). The difference of Dmax between the original and 4D dose distributions ranged from 9.1 cGy (esophagus motion: 5.6 mm) to 231.1 cGy (esophagus motion: 3.1 mm). The difference of D(5cc) ranged from 5 cGy (esophagus motion: 3.1 mm) to 85 cGy (esophagus motion: 3.3 mm). There was no correlation between the dosimetric deviation and the motion magnitude. The V(11.9Gy)<5cc constraint was met for each patient when examining the DVH calculated from the 4D dose. Conclusion: Respiratory motion did not result in substantial dose increase to esophagus in spine SBRT. 4DCT simulation may not be necessary with regards to esophageal dose assessment.

Neuroticism and responses to social comparison among cancer patients

NARCIS (Netherlands)

Buunk, A.P.; Brakel, T.M.; Bennenbroek, F.T.C.; Stiegelis, H.E.; Sanderman, R.; Bergh, A.C.M. van den; Hagedoorn, M.

2009-01-01

The present study examined how the effects of three audiotapes containing different types of social comparison information on the mood of cancer patients depended on the level of neuroticism. On the procedural tape, a man and woman discussed the process of radiation therapy, on the emotion tape,

Conventional Versus Automated Implantation of Loose Seeds in Prostate Brachytherapy: Analysis of Dosimetric and Clinical Results

International Nuclear Information System (INIS)

Genebes, Caroline; Filleron, Thomas; Graff, Pierre; Jonca, Frédéric; Huyghe, Eric; Thoulouzan, Matthieu; Soulie, Michel; Malavaud, Bernard; Aziza, Richard; Brun, Thomas; Delannes, Martine; Bachaud, Jean-Marc

2013-01-01

Purpose: To review the clinical outcome of I-125 permanent prostate brachytherapy (PPB) for low-risk and intermediate-risk prostate cancer and to compare 2 techniques of loose-seed implantation. Methods and Materials: 574 consecutive patients underwent I-125 PPB for low-risk and intermediate-risk prostate cancer between 2000 and 2008. Two successive techniques were used: conventional implantation from 2000 to 2004 and automated implantation (Nucletron, FIRST system) from 2004 to 2008. Dosimetric and biochemical recurrence-free (bNED) survival results were reported and compared for the 2 techniques. Univariate and multivariate analysis researched independent predictors for bNED survival. Results: 419 (73%) and 155 (27%) patients with low-risk and intermediate-risk disease, respectively, were treated (median follow-up time, 69.3 months). The 60-month bNED survival rates were 95.2% and 85.7%, respectively, for patients with low-risk and intermediate-risk disease (P=.04). In univariate analysis, patients treated with automated implantation had worse bNED survival rates than did those treated with conventional implantation (P<.0001). By day 30, patients treated with automated implantation showed lower values of dose delivered to 90% of prostate volume (D90) and volume of prostate receiving 100% of prescribed dose (V100). In multivariate analysis, implantation technique, Gleason score, and V100 on day 30 were independent predictors of recurrence-free status. Grade 3 urethritis and urinary incontinence were observed in 2.6% and 1.6% of the cohort, respectively, with no significant differences between the 2 techniques. No grade 3 proctitis was observed. Conclusion: Satisfactory 60-month bNED survival rates (93.1%) and acceptable toxicity (grade 3 urethritis <3%) were achieved by loose-seed implantation. Automated implantation was associated with worse dosimetric and bNED survival outcomes

Conventional Versus Automated Implantation of Loose Seeds in Prostate Brachytherapy: Analysis of Dosimetric and Clinical Results

Energy Technology Data Exchange (ETDEWEB)

Genebes, Caroline, E-mail: genebes.caroline@claudiusregaud.fr [Radiation Oncology Department, Institut Claudius Regaud, Toulouse (France); Filleron, Thomas; Graff, Pierre [Radiation Oncology Department, Institut Claudius Regaud, Toulouse (France); Jonca, Frédéric [Department of Urology, Clinique Ambroise Paré, Toulouse (France); Huyghe, Eric; Thoulouzan, Matthieu; Soulie, Michel; Malavaud, Bernard [Department of Urology and Andrology, CHU Rangueil, Toulouse (France); Aziza, Richard; Brun, Thomas; Delannes, Martine; Bachaud, Jean-Marc [Radiation Oncology Department, Institut Claudius Regaud, Toulouse (France)

2013-11-15

Purpose: To review the clinical outcome of I-125 permanent prostate brachytherapy (PPB) for low-risk and intermediate-risk prostate cancer and to compare 2 techniques of loose-seed implantation. Methods and Materials: 574 consecutive patients underwent I-125 PPB for low-risk and intermediate-risk prostate cancer between 2000 and 2008. Two successive techniques were used: conventional implantation from 2000 to 2004 and automated implantation (Nucletron, FIRST system) from 2004 to 2008. Dosimetric and biochemical recurrence-free (bNED) survival results were reported and compared for the 2 techniques. Univariate and multivariate analysis researched independent predictors for bNED survival. Results: 419 (73%) and 155 (27%) patients with low-risk and intermediate-risk disease, respectively, were treated (median follow-up time, 69.3 months). The 60-month bNED survival rates were 95.2% and 85.7%, respectively, for patients with low-risk and intermediate-risk disease (P=.04). In univariate analysis, patients treated with automated implantation had worse bNED survival rates than did those treated with conventional implantation (P<.0001). By day 30, patients treated with automated implantation showed lower values of dose delivered to 90% of prostate volume (D90) and volume of prostate receiving 100% of prescribed dose (V100). In multivariate analysis, implantation technique, Gleason score, and V100 on day 30 were independent predictors of recurrence-free status. Grade 3 urethritis and urinary incontinence were observed in 2.6% and 1.6% of the cohort, respectively, with no significant differences between the 2 techniques. No grade 3 proctitis was observed. Conclusion: Satisfactory 60-month bNED survival rates (93.1%) and acceptable toxicity (grade 3 urethritis <3%) were achieved by loose-seed implantation. Automated implantation was associated with worse dosimetric and bNED survival outcomes.

Monte Carlo calculations and experimental measurements of dosimetric parameters of the IRA-103Pd source

International Nuclear Information System (INIS)

Sadeghi, Mahdi; Hosseini, Hamed; Raisali, Gholamreza

2008-01-01

Full text: The use of 103 Pd seed sources for permanent prostate implantation has become a popular brachytherapy application. As recommended by AAPM the dosimetric characteristics of the new source must be determined using experimental and Monte Carlo simulations, before its use in clinical applications thus The goal of this report is the experimental and theoretical determination of the dosimetric characteristics of this source following the recommendations in the AAPM TG-43U1 protocol. Figure 1 shows the geometry of the IRA- 103 Pd source. The source consists of a cylindrical silver core, 0.3 cm long x 0.05 cm in diameter, onto which 0.5 nm layer of 103 Pd has been uniformly adsorbed. The effective active length of source is 0.3 cm and the silver core encapsulated inside a hollow titanium tube with 0.45 cm long, 0.07 cm and 0.08 inner and outer diameters and two caps. The Monte Carlo N-Particle (MCNP) code, version 4C, was used to determine the relevant dosimetric parameters of the source. The geometry of the Monte Carlo simulation performed in this study consisted of a sphere with 30 cm diameter. Dose distributions around this source were measured in two Perspex phantom using enough TLD chips. For these measurements, slabs of Perspex material were machined to accommodate the source and TLD chips. A value of 0.67± 1% cGy.h -1 .U -1 for, Λ, was calculated as the ratio of d(r 0 ,θ 0 ) and s K , that may be compared with Λ values obtained for 103 Pd sources. Result of calculations and measurements values of dosimetric parameters of the source including radial dose function, g(r), and anisotropy function, F(r,θ), has been shown in separate figures. The radial dose function, g(r), for the IRA- 103 Pd source and other 103 Pd sources is included in Fig. 2. Comparison between measured and Monte Carlo simulated dose function, g(r), and anisotropy function, F(r,θ), of this source demonstrated that they are in good agreement with each other and The value of Λ is

Dosimetric impact of systematic MLC positional errors on step and shoot IMRT for prostate cancer: a planning study

International Nuclear Information System (INIS)

Ung, N.M.; Wee, L.; Harper, C.S.

2010-01-01

Full text: The positional accuracy of multi leaf collimators (MLC) is crucial in ensuring precise delivery of intensity-modulated radiotherapy (IMRT). The aim of this planning study was to investigate the dosimetric impact of systematic MLC errors on step and shoot IMRT of prostate cancer. Twelve MLC leaf banks perturbations were introduced to six prostate IMRT treatment plans to simulate MLC systematic errors. Dose volume histograms (OYHs) were generated for the extraction of dose endpoint parameters. Plans were evaluated in terms of changes to the defined endpoint dose parameters, conformity index (CI) and healthy tissue avoidance (HTA) to planning target volume (PTY), rectum and bladder. Negative perturbations of MLC had been found to produce greater changes to endpoint dose parameters than positive perturbations of MLC (p < 0.05). Negative and positive synchronized MLC perturbations of I mm resulted in median changes of -2.32 and 1.78%, respectively to 095% of PTY whereas asynchronized MLC perturbations of the same direction and magnitude resulted in median changes of 1.18 and 0.90%, respectively. Doses to rectum were generally more sensitive to systematic MLC errors compared to bladder. Synchronized MLC perturbations of I mm resulted in median changes of endpoint dose parameters to both rectum and bladder from about I to 3%. Maximum reduction of -4.44 and -7.29% were recorded for CI and HTA, respectively, due to synchronized MLC perturbation of I mm. In summary, MLC errors resulted in measurable amount of dose changes to PTY and surrounding critical structures in prostate LMRT. (author)

Dosimetric effect on pediatric conformal treatment plans using dynamic jaw with Tomotherapy HDA.

Science.gov (United States)

Han, Eun Young; Kim, Dong-Wook; Zhang, Xin; Penagaricano, Jose; Liang, Xiaoying; Hardee, Matthew; Morrill, Steve; Ratanatharathorn, Vaneerat

2015-01-01

It is important to minimize the radiation dose delivered to healthy tissues in pediatric cancer treatment because of the risk of secondary malignancies. Tomotherapy HDA provides a dynamic jaw (DJ) delivery mode that creates a sharper penumbra at the craniocaudal ends of a target in addition to a fixed jaw (FJ) delivery mode. The purpose of this study was to evaluate its dosimetric effect on the pediatric cancer cases. We included 6 pediatric cases in this study. The dose profiles and plan statistics—target dose conformity, uniformity, organ-at-risk (OAR) mean dose, beam-on time, and integral dose—were compared for each case. Consequently, the target dose coverage and uniformity were similar for different jaw settings. The OAR dose sparing depended on its relative location to the target and disease sites. For example, in the head and neck cancer cases, the brain stem dose using DJ 2.5 was reduced by more than two-fold (2.4 Gy vs. 6.3 Gy) than that obtained with FJ 2.5. The integral dose with DJ 2.5 decreased by more than 9% compared with that with FJ 2.5. Thus, using dynamic jaw in pediatric cases could be critical to reduce a probability of a secondary malignancy. Copyright © 2015 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Dosimetric comparison for volumetric modulated arc therapy and intensity-modulated radiotherapy on the left-sided chest wall and internal mammary nodes irradiation in treating post-mastectomy breast cancer

International Nuclear Information System (INIS)

Zhang, Qian; Yu, Xiao Li; Hu, Wei Gang; Chen, Jia Yi; Wang, Jia Zhou; Ye, Jin Song; Guo, Xiao Mao

2015-01-01

The aim of the study was to evaluate the dosimetric benefit of applying volumetric modulated arc therapy (VMAT) on the post-mastectomy left-sided breast cancer patients, with the involvement of internal mammary nodes (IMN). The prescription dose was 50 Gy delivered in 25 fractions, and the clinical target volume included the left chest wall (CW) and IMN. VMAT plans were created and compared with intensity-modulated radiotherapy (IMRT) plans on Pinnacle treatment planning system. Comparative endpoints were dose homogeneity within planning target volume (PTV), target dose coverage, doses to the critical structures including heart, lungs and the contralateral breast, number of monitor units and treatment delivery time. VMAT and IMRT plans showed similar PTV dose homogeneity, but, VMAT provided a better dose coverage for IMN than IMRT (p = 0.017). The mean dose (Gy), V 30 (%) and V 10 (%) for the heart were 13.5 ± 5.0 Gy, 9.9% ± 5.9% and 50.2% ± 29.0% by VMAT, and 14.0 ± 5.4 Gy, 10.6% ± 5.8% and 55.7% ± 29.6% by IMRT, respectively. The left lung mean dose (Gy), V 20 (%), V 10 (%) and the right lung V 5 (%) were significantly reduced from 14.1 ± 2.3 Gy, 24.2% ± 5.9%, 42.4% ± 11.9% and 41.2% ± 12.3% with IMRT to 12.8 ± 1.9 Gy, 21.0% ± 3.8%, 37.1% ± 8.4% and 32.1% ± 18.2% with VMAT, respectively. The mean dose to the contralateral breast was 1.7 ± 1.2 Gy with VMAT and 2.3 ± 1.6 Gy with IMRT. Finally, VMAT reduced the number of monitor units by 24% and the treatment time by 53%, as compared to IMRT. Compared to 5-be am step-and-shot IMRT, VMAT achieves similar or superior target coverage and a better normal tissue sparing, with fewer monitor units and shorter delivery time

Potential application of metal nanoparticles for dosimetric systems: Concepts and perspectives

Energy Technology Data Exchange (ETDEWEB)

Guidelli, Eder José, E-mail: ederguidelli@pg.ffclrp.usp.br; Baffa, Oswaldo, E-mail: ederguidelli@pg.ffclrp.usp.br [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP (Brazil)

2014-11-07

Metallic nanoparticles increase the delivered dose and consequently enhance tissue radio sensitization during radiation therapy of cancer. The Dose Enhancement Factor (DEF) corresponds to the ratio between the dose deposited on a tissue containing nanoparticles, and the dose deposited on a tissue without nanoparticles. In this sense, we have used electron spin resonance spectroscopy (ESR) to investigate how silver and gold nanoparticles affect the dose deposition in alanine dosimeters, which act as a surrogate of soft tissue. Besides optimizing radiation absorption by the dosimeter, the optical properties of these metal nanoparticles could also improve light emission from materials employed as radiation detectors. Therefore, we have also examined how the plasmonic properties of noble metal nanoparticles could enhance radiation detection using optically stimulated luminescence (OSL) dosimetry. This work will show results on how the use of gold and silver nanoparticles are beneficial for the ESR and OSL dosimetric techniques, and will describe the difficulties we have been facing, the challenges to overcome, and the perspectives.

Potential dosimetric benefits of adaptive tumor tracking over the internal target volume concept for stereotactic body radiation therapy of pancreatic cancer.

Science.gov (United States)

Karava, Konstantina; Ehrbar, Stefanie; Riesterer, Oliver; Roesch, Johannes; Glatz, Stefan; Klöck, Stephan; Guckenberger, Matthias; Tanadini-Lang, Stephanie

2017-11-09

Radiotherapy for pancreatic cancer has two major challenges: (I) the tumor is adjacent to several critical organs and, (II) the mobility of both, the tumor and its surrounding organs at risk (OARs). A treatment planning study simulating stereotactic body radiation therapy (SBRT) for pancreatic tumors with both the internal target volume (ITV) concept and the tumor tracking approach was performed. The two respiratory motion-management techniques were compared in terms of doses to the target volume and organs at risk. Two volumetric-modulated arc therapy (VMAT) treatment plans (5 × 5 Gy) were created for each of the 12 previously treated pancreatic cancer patients, one using the ITV concept and one the tumor tracking approach. To better evaluate the overall dose delivered to the moving tumor volume, 4D dose calculations were performed on four-dimensional computed tomography (4DCT) scans. The resulting planning target volume (PTV) size for each technique was analyzed. Target and OAR dose parameters were reported and analyzed for both 3D and 4D dose calculation. Tumor motion ranged from 1.3 to 11.2 mm. Tracking led to a reduction of PTV size (max. 39.2%) accompanied with significant better tumor coverage (p<0.05, paired Wilcoxon signed rank test) both in 3D and 4D dose calculations and improved organ at risk sparing. Especially for duodenum, stomach and liver, the mean dose was significantly reduced (p<0.05) with tracking for 3D and 4D dose calculations. By using an adaptive tumor tracking approach for respiratory-induced pancreatic motion management, a significant reduction in PTV size can be achieved, which subsequently facilitates treatment planning, and improves organ dose sparing. The dosimetric benefit of tumor tracking is organ and patient-specific.

Basic principles and practices of integrated dosimetric passportization of the settlements in Ukraine

International Nuclear Information System (INIS)

Lyikhtar'ov, Yi.A.; Kovgan, L.M.; Masyuk, S.V.; Yivanova, O.M.; Chepurnij, M.Yi.; Bojko, Z. N.; Gerasimenko, V.B.

2015-01-01

The objective of the review is to demonstrate the results of dosimetric passportization (performed in 1991- 2014) for the settlements of Ukraine which suffered from radioactive contamination caused by the Chornobyl accident. The dosimetric passportization played a key role in the National program on the liquidation of after- math of the Chornobyl accident through all stages of the current radiation situation control and decision support touching upon various types of interventions and social benefits to the population of radioactively contaminated areas. The works being performed under dosimetric passportization did not have analogues among the researches which took place after other large-scale industrial and municipal accidents as well their scales as the duration of both radio-ecological and dosimetric monitoring. The new methodological approaches to the assessment of so-called passport doses of a settlement as well as to the definition of the concept of annual dose being the dose used to make decisions for providing both direct and indirect emergency countermeasures for the settlements of Ukraine became pioneering ones. During all the post-accident period there were issued sixteen collections of general dosimetric passportization data which accumulate the results of hundreds of thousands spectrometric, radiochemical and radiation levels measurements and WBC measurements carried out in 1991-2014. The annual passport doses calculated on the basis of these measurements (including their components) are unique information that quantifies the level and time dynamics of the radiation situation for each of the 2161 settlements of 74 districts in 12 regions during all the post-accident period. Thanks to the works of dosimetric passportization of the settlements of Ukraine there were created databases to be unique in their structure and content with quantitative characteristics of the territorial and temporal distribution, the dynamics of changes of a number of important

Our experience with the acceptance and dosimetric validation of Somatom Force dual head MDCT in the Royal Hospital, Oman

International Nuclear Information System (INIS)

Al-Harthi, Ruqaia; Al-Kalbani, Munira; Arun Kumar, L.S.; Al-Shanfari, Jamal

2017-01-01

Computed Tomography (CT) has revolutionized diagnostic imaging since its discovery in early 70's. In Oman; 70,353 CT examinations were carried out in the year 2015. The increase in CT examinations will eventually result in the increase of population dose and the consequent risk of cancer in adults and particularly in children. Here, we discuss and share our experience with the acceptance and dosimetric validation of second Dual Head Somatom Force MDCT installed in the Royal Hospital, Oman using Ministry of Health's radiation acceptance and quality assurance protocol, before handing over for routine patient care work

SU-F-T-240: EPID-Based Quality Assurance for Dosimetric Credentialing

Energy Technology Data Exchange (ETDEWEB)

Miri, N [University of Newcastle, Newcastle, NSW (Australia); Lehmann, J [Calvary Mater Newcastle, Newcastle, NSW (Australia); Vial, P [Liverpool Hospital, Sydney, NSW (Australia); Greer, P [Calvary Mater Newcastle, Newcastle, NSW (Australia); University of Newcastle, Newcastle, NSW (Australia)

2016-06-15

Purpose: We propose a novel dosimetric audit method for clinical trials using EPID measurements at each center and a standardized EPID to dose conversion algorithm. The aim of this work is to investigate the applicability of the EPID method to different linear accelerator, EPID and treatment planning system (TPS) combinations. Methods: Combination of delivery and planning systems were three Varian linacs including one Pinnacle and two Eclipse TPS and, two ELEKTA linacs including one Pinnacle and one Monaco TPS. All Varian linacs had the same EPID structure and similarly for the ELEKTA linacs. Initially, dose response of the EPIDs was investigated by acquiring integrated pixel value (IPV) of the central area of 10 cm2 images versus MUs, 5-400 MU. Then, the EPID to dose conversion was investigated for different system combinations. Square field size images, 2, 3, 4, 6, 10, 15, 20, 25 cm2 acquired by all systems were converted to dose at isocenter of a virtual flat phantom then the dose was compared to the corresponding TPS dose. Results: All EPIDs showed a relatively linear behavior versus MU except at low MUs which showed irregularities probably due to initial inaccuracies of irradiation. Furthermore, for all the EPID models, the model predicted TPS dose with a mean dose difference percentage of 1.3. However the model showed a few inaccuracies for ELEKTA EPID images at field sizes larger than 20 cm2. Conclusion: The EPIDs demonstrated similar behavior versus MU and the model was relatively accurate for all the systems. Therefore, the model could be employed as a global dosimetric method to audit clinical trials. Funding has been provided from Department of Radiation Oncology, TROG Cancer Research and the University of Newcastle. Narges Miri is a recipient of a University of Newcastle postgraduate scholarship.

Thermoluminescence dosimetric characteristics of thulium doped ZnB2O4 phosphor

International Nuclear Information System (INIS)

Annalakshmi, O.; Jose, M.T.; Madhusoodanan, U.; Subramanian, J.; Venkatraman, B.; Amarendra, G.; Mandal, A.B.

2014-01-01

Polycrystalline powder samples of rare earth doped Zinc borates were synthesized by high temperature solid state diffusion technique. Dosimetric characteristics of the phosphor like thermoluminescence glow curve, TL emission spectra, dose–response, fading studies, reproducibility and reusability studies were carried out on the synthesized phosphors. Among the different rare earth doped phosphors, thulium doped zinc borate was found to have a higher sensitivity. Hence detailed dosimetric characteristics of this phosphor were carried out. It is observed that the dose–response is linear from 10 mGy to 10 3 Gy in this phosphor. EPR measurements were carried out on unirradiated, gamma irradiated and annealed phosphors to identify the defect centers responsible for thermoluminescence. A TL model is proposed based on the EPR studies in these materials. Kinetic parameters were evaluated for the dosimetric peaks using various methods. The experimental results show that this phosphor can have potential applications in radiation dosimetry applications. -- Highlights: • Polycrystalline powder samples of rare earth doped zinc borates were synthesized. • Thulium was observed to be the most efficient dopant in ZnB 2 O 4 lattice. • TL intensity of the dosimetric peak is around 20 times that of TLD-100. • Based on EPR studies a TL mechanism is proposed in zinc borate. • Deconvolution of the glow curve carried out

Dosimetric characterization of a bi-directional micromultileaf collimator for stereotactic applications.

Science.gov (United States)

Bucciolini, M; Russo, S; Banci Buonamici, F; Pini, S; Silli, P

2002-07-01

A 6 MV photon beam from Linac SL75-5 has been collimated with a new micromultileaf device that is able to shape the field in the two orthogonal directions with four banks of leaves. This is the first clinical installation of the collimator and in this paper the dosimetric characterization of the system is reported. The dosimetric parameters required by the treatment planning system used for the dose calculation in the patient are: tissue maximum ratios, output factors, transmission and leakage of the leaves, penumbra values. Ionization chambers, silicon diode, radiographic films, and LiF thermoluminescent dosimeters have been employed for measurements of absolute dose and beam dosimetric data. Measurements with different dosimeters supply results in reasonable agreement among them and consistent with data available in literature for other models of micromultileaf collimator; that permits the use of the measured parameters for clinical applications. The discrepancies between results obtained with the different detectors (around 2%) for the analyzed parameters can be considered an indication of the accuracy that can be reached by current stereotactic dosimetry.

Determination of Dosimetric Parameters of the Second Model of Pd-103 Seed Manufactured at Agricultural, Medical and Industrial Research School

Directory of Open Access Journals (Sweden)

Gholamreza Raisali

2008-06-01

Full Text Available Introduction: The use of low energy isotopes such as  103 Pd in brachytherapy for the treatment of cancers  such as prostate, eye, head, neck, breast and cervix is increasing. In this regard, different models of Pd- 103  seeds  have  been  designed  and  manufactured  at  the  Agricultural,  Medical  and  Industrial  Research  School (AMIRS of Atomic Energy Organization of Iran. In this research, the dosimetric parameters of  the second model of Pd-103 seed manufactured at AMIRS have been calculated and measured.   Materials and Methods: The dosimetric parameters of the second Pd-103 seed manufactured at AMIRS  were determined according to TG-43U1 protocol using Monte Carlo calculations (MCNP4C computer  code  and  measurements  performed  using  TLD-GR200A  dosimeters  in  a  Perspex  phantom.  The  parameters  include  dose  rate  constant,  geometry  function,  radial  dose  function,  anisotropy  function,  anisotropy factor and anisotropy constant.  Results:  It  was  found  that  by  using  MCNP4C  code  the  calculated  dose  rate  constant  in  water  and  Perspex  was  0.706±0.001   and  0.501±0.001  cGyh -1 U -1 , respectively.  Using  the  calculated  geometry  function,  the  radial  dose  function  and  the  anisotropy  function  were  determined  by  experimental  and  theoretical methods in water and Perspex phantom. Also, the calculated value of anisotropy constant in  water was equal to 0.88.  Discussion and Conclusion: A discrepancy of less than 10% between the calculated and the measured  values indicates a reasonable agreement between the simulation and the measurement method. Also, the  dosimetric parameters of this seed have been compared to the dosimetric parameters of the first Pd-103  seed  manufactured  at  AMIRS  and  some  other  seeds.  The  obtained  results  indicate  that  the  seeds  manufactured at AMIRS

Dosimetric study for characterization of a postal system of quality control in brachytherapy

International Nuclear Information System (INIS)

Alves, Victor Gabriel Leandro; Queiroz Filho, Pedro Pacheco de; Santos, Denison de Souza; Begalli, Marcia

2009-01-01

This work presents a dosimetric study of a postal system, to be developed for measurements of brachytherapy. It was projected a PMMA phantom with orifices for insertion of the high dose 192 Ir source and the T L dosemeters. The system was characterized with using of Monte Carlo simulations, using the dosimetric magnitudes defined at the T G-43 of AAPM, as function of radial dose g(f)

Management and processing of dosimetric data of workers exposed to ionizing radiation

International Nuclear Information System (INIS)

Rasoarimalala, T.

2012-01-01

The Madagascar - INSTN Radiation protection and Dosimetry Department use the reader HARSHAW TLD 6600 for workers doses reading. Although the performance of this device, manual works is required to store and to maintain the dosimetric data after reading and to note the TLDs sent to the establishments. To avoid these manual works, this present work proposes computer programs written in Python and using SQLite software. One of the programs in python retrieves dose values after reading and transfers directly these doses in the workers database. The use of SQLite software provides a way for the dosimetric data management and the TLDs movement monitoring. The other program assesses estimation of the dose received by worker through a trend curve for workers dosimetric monitoring. The calculated differences of this curve over the curve connecting all points are less than 20%, acceptable limit in radiation protection for TLDs. This present work presents then significances for the personnel occupying individual monitoring of ionizing radiation workers and for these workers too. [fr

Prevalence of bile duct cancer among printing industry workers in comparison with other industries.

Science.gov (United States)

Okamoto, Etsuji; Kikuchi, Kiyotaka; Endo, Ginji

2013-01-01

The aim of this study was to assess the risk of developing bile duct cancer among workers in the other printing industry in comparison with workers in all industries in general. Prevalence of bile duct cancer was compared between workers in the printing industry and age-standardized controls in all other industries using the claims database of the Japan Health Insurance Association, which insures workers of small-medium sized employers of all industries. Young (aged 30-49) male workers in the printing industry showed an elevated but insignificant standardized prevalence rate ratio (SPRR) for bile duct cancer in comparison with workers in all other industries (SPRR: 1.78; 95%CI: 0.63-5.00). The risk was higher for intrahepatic bile duct cancer but remained insignificant (SPRR: 3.03; 95%CI: 0.52-17.56). The sharply elevated risk of bile duct cancer observed among proof-printing workers of a printing factory in Osaka may not be generalizable to workers in the printing industry nationwide.

Dosimetric characterization of the Exradin W1 plastic scintillator detector through comparison with an in-house developed scintillator system

DEFF Research Database (Denmark)

Beierholm, Anders Ravnsborg; Behrens, Claus F.; Andersen, Claus E.

2014-01-01

method, but differing primarily in the signal detection hardware. The two systems were compared with respect to essential dosimetric properties, with the purpose of testing their performance under conditions less well discussed in the literature. A Farmer ionization chamber was used as the primary...... is therefore advised if using either system for measurements in large fields or under circumstances where the fibre irradiation geometry is unfavourable. Measurements of reference dose to water yielded differences up to 1.5% when compared with the Farmer ionization chamber for all investigated beam qualities...

Dosimetric results in implant and post-implant and low rate in brachytherapy prostate cancer with loose seeds and attached; Resultados dosimetricos en el implante y post-impante en braquiterapia de baja tasa en cancer de prostata con semillas sueltas y unidas

Energy Technology Data Exchange (ETDEWEB)

Juan-Senabre, X. J.; Albert Antequera, M.; Lopez-Tarjuelo, J.; Santos Serra, A.; Perez-Mestre, M.; Sanchez Iglesias, A. L.; Conde Moreno, A. J.; Gonzalez Vidal, V.; Beltran Persiva, J.; Muelas Soria, R.; Ferrer Albiach, C.

2015-07-01

The objective is determine differences dosimetry statistics on the dosimetry of the implant and post-implant in brachytherapy of low rate with implants permanent in prostate using seed of 125-I loose and attached Both in lives and in the post-prostatic plans dosimetric coverage is good and restrictions in urethra and rectum for both groups of patients are met. Not migrating with joined is evident, as well as better dosimetric homogeneity. (Author)

Dosimetric considerations and radiation protection of patients in interventional cardiology

International Nuclear Information System (INIS)

Ciraj-Bjelac, O.; Arandjic, D.; Kosutic, D.; Loncar, B.

2009-01-01

The paper summarizes results of measurements of relevant dosimetric quantities in interventional cardiology. Dosimetric data were collected for 117 coronary angiography (CA) procedures, 69 percutaneous coronary interventions (PCI) and 41 combined procedures (CA+PCI), taking into account two quantities: air kerma area product (KAP) d air kerma in international reference point (K IRP ). Mean KAP values were 78 Gy·cm 2 , 113 Gy·cm 2 and 141 Gy·cm 2 for CA, PCI i CA+PCI, respectively. Corresponding mean K IRP values were 1.2 Gy, 1.8 Gy and 2.2 Gy. With respect to high dose values, risk for stochastic effects and tissue reactions, dose management methods were proposed. (author) [sr

CT images and radiotherapy treatment planning of patients with breast cancer: A dataset

Directory of Open Access Journals (Sweden)

Mohammad Rezaei

2017-08-01

Full Text Available The data presented here were originally collected for the research project “CT-Scan processing and analysis in patient with breast cancer after radiotherapy”. Also, it reported in our study “Prediction of Lung Tissue Damage by Evaluating Clinical and Dosimetric Parameters in Breast Cancer Patients” (Hasanabdali et al., 2016 [1]. This article describes and directly links to 52 subjects referred to Mahdieh Oncology and Radiotherapy Center from February to August 2015. Treatment planning was done for delivering 50 Gy dose to PTV in 25 fractions. the lungs and heart objects were extracted from CT images along with compliance Dose plan. Dose-volume histogram (DVH and Dose-mass histogram (DMH extracted using CT images and dose plan matrix. Moreover, the complete clinical and dosimetric specifications of subjects is attached.

Potential benefits of dosimetric VMAT tracking verified with 3D film measurements

Energy Technology Data Exchange (ETDEWEB)

Crijns, Wouter, E-mail: wouter.crijns@uzleuven.be; Depuydt, Tom; Haustermans, Karin [Laboratory of Experimental Radiotherapy, KU Leuven Department of Oncology, Herestraat 49, 3000 Leuven (Belgium); Radiation Oncology, University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium); Defraene, Gilles [Laboratory of Experimental Radiotherapy, KU Leuven Department of Oncology, Herestraat 49, 3000 Leuven, Belgium and KU Leuven Medical Imaging Research Center, Herestraat 49, 3000 Leuven (Belgium); Van Herck, Hans [KU Leuven Medical Imaging Research Center, Herestraat 49, 3000 Leuven, Belgium and KU Leuven Department of Electrical Engineering (ESAT)–PSI, Center for Processing Speech and Images, 3000 Leuven (Belgium); Maes, Frederik [KU Leuven Medical Imaging Research Center, Herestraat 49, 3000 Leuven (Belgium); KU Leuven Department of Electrical Engineering (ESAT)–PSI, Center for Processing Speech and Images, 3000 Leuven (Belgium); Medical IT Department, KU Leuven iMinds, 3000 Leuven (Belgium); Van den Heuvel, Frank [Department of Oncology, MRC-CR-UK Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford OX1 2JD (United Kingdom)

2016-05-15

Purpose: To evaluate three different plan adaptation strategies using 3D film-stack dose measurements of both focal boost and hypofractionated prostate VMAT treatments. The adaptation strategies (a couch shift, geometric tracking, and dosimetric tracking) were applied for three realistic intrafraction prostate motions. Methods: A focal boost (35 × 2.2 and 35 × 2.7 Gy) and a hypofractionated (5 × 7.25 Gy) prostate VMAT plan were created for a heterogeneous phantom that allows for internal prostate motion. For these plans geometric tracking and dosimetric tracking were evaluated by ionization chamber (IC) point dose measurements (zero-D) and measurements using a stack of EBT3 films (3D). The geometric tracking applied translations, rotations, and scaling of the MLC aperture in response to realistic prostate motions. The dosimetric tracking additionally corrected the monitor units to resolve variations due to difference in depth, tissue heterogeneity, and MLC-aperture. The tracking was based on the positions of four fiducial points only. The film measurements were compared to the gold standard (i.e., IC measurements) and the planned dose distribution. Additionally, the 3D measurements were converted to dose volume histograms, tumor control probability, and normal tissue complication probability parameters (DVH/TCP/NTCP) as a direct estimate of clinical relevance of the proposed tracking. Results: Compared to the planned dose distribution, measurements without prostate motion and tracking showed already a reduced homogeneity of the dose distribution. Adding prostate motion further blurs the DVHs for all treatment approaches. The clinical practice (no tracking) delivered the dose distribution inside the PTV but off target (CTV), resulting in boost dose errors up to 10%. The geometric and dosimetric tracking corrected the dose distribution’s position. Moreover, the dosimetric tracking could achieve the planned boost DVH, but not the DVH of the more homogeneously

Dosimetric measurements of an n-butyl cyanoacrylate embolization material for arteriovenous malformations

Energy Technology Data Exchange (ETDEWEB)

Labby, Zacariah E., E-mail: zelabby@humonc.wisc.edu [Department of Human Oncology, University of Wisconsin–Madison, 600 Highland Avenue, Madison, Wisconsin 53792 (United States); Chaudhary, Neeraj [Division of Neurointerventional Radiology, Departments of Radiology and Neurosurgery, University of Michigan Hospital and Health Systems, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 (United States); Gemmete, Joseph J. [Division of Neurointerventional Radiology, Departments of Radiology, Neurosurgery, and Otolaryngology, University of Michigan Hospital and Health Systems, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 (United States); Pandey, Aditya S. [Department of Neurosurgery, University of Michigan Hospital and Health Systems, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 (United States); Roberts, Donald A. [Radiation Physics Division, Department of Radiation Oncology, University of Michigan Hospital and Health Systems, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 (United States)

2015-04-15

Purpose: The therapeutic regimen for cranial arteriovenous malformations often involves both stereotactic radiosurgery and endovascular embolization. Embolization agents may contain tantalum or other contrast agents to assist the neurointerventionalists, leading to concerns regarding the dosimetric effects of these agents. This study investigated dosimetric properties of n-butyl cyanoacrylate (n-BCA) plus lipiodol with and without tantalum powder. Methods: The embolization agents were provided cured from the manufacturer with and without added tantalum. Attenuation measurements were made for the samples and compared to the attenuation of a solid water substitute using a 6 MV photon beam. Effective linear attenuation coefficients (ELAC) were derived from attenuation measurements made using a portal imager and derived sample thickness maps projected in an identical geometry. Probable dosimetric errors for calculations in which the embolized regions are overridden with the properties of water were calculated using the ELAC values. Interface effects were investigated using a parallel plate ion chamber placed at set distances below fixed samples. Finally, Hounsfield units (HU) were measured using a stereotactic radiosurgery CT protocol, and more appropriate HU values were derived from the ELAC results and the CT scanner’s HU calibration curve. Results: The ELAC was 0.0516 ± 0.0063 cm{sup −1} and 0.0580 ± 0.0091 cm{sup −1} for n-BCA without and with tantalum, respectively, compared to 0.0487 ± 0.0009 cm{sup −1} for the water substitute. Dose calculations with the embolized region set to be water equivalent in the treatment planning system would result in errors of −0.29% and −0.93% per cm thickness of n-BCA without and with tantalum, respectively. Interface effects compared to water were small in magnitude and limited in distance for both embolization materials. CT values at 120 kVp were 2082 and 2358 HU for n-BCA without and with tantalum, respectively

Comparative study of main dosimetric characteristics between the GR-200A and MCP-N LiF (Mg, Cu, P) TLD chips

International Nuclear Information System (INIS)

Shen Wenxiu; Tang Kaiyong; Wang Shoushan; Cai Gangang; Zhu Hongying; Lu Min

1999-01-01

GR-200A and MCP-N are the same kind of LiF(Mg, Cu, P) chip detectors. The main dosimetric characteristics of two LiF (Mg, Cu, P) chip TLDs (GR-200A made in Solid Dosimetric Detector and Method Laboratory, Beijing, and MCP-N made in Poland) are compared, including glow curve structure, TL sensitivity, anti-moisture, reproducibility, background, detection threshold and photosensitivity. Sensitivity of GR-200a is 1.6 times as much as that of MCP-N. The sensitivity of GR-200A is stable after being used for six times, but the sensitivity of MCP-N dropped 2.8%, and its colour turned from white into light brown. The sensitivity and colour of GR-200A did not vary after being stored for 25 days at 98% RH, by comparison the sensitivity of MCP-N dropped 14%, and its colour turned into light brown. It was found that the GR-200A TLD is superior to the MCP-N TLD in above-mentioned characteristics

Proton therapy radiation pneumonitis local dose–response in esophagus cancer patients

International Nuclear Information System (INIS)

Echeverria, Alfredo E.; McCurdy, Matthew; Castillo, Richard; Bernard, Vincent; Ramos, Natalia Velez; Buckley, William; Castillo, Edward; Liu, Ping; Martinez, Josue; Guerrero, Thomas

2013-01-01

Purpose: This study quantifies pulmonary radiation toxicity in patients who received proton therapy for esophagus cancer. Materials/methods: We retrospectively studied 100 esophagus cancer patients treated with proton therapy. The linearity of the enhanced FDG uptake vs. proton dose was evaluated using the Akaike Information Criterion (AIC). Pneumonitis symptoms (RP) were assessed using the Common Toxicity Criteria for Adverse Events version 4.0 (CTCAEv4). The interaction of the imaging response with dosimetric parameters and symptoms was evaluated. Results: The RP scores were: 0 grade 4/5, 7 grade 3, 20 grade 2, 37 grade 1, and 36 grade 0. Each dosimetric parameter was significantly higher for the symptomatic group. The AIC winning models were 30 linear, 52 linear quadratic, and 18 linear logarithmic. There was no significant difference in the linear coefficient between models. The slope of the FDG vs. proton dose response was 0.022 for the symptomatic and 0.012 for the asymptomatic (p = 0.014). Combining dosimetric parameters with the slope did not improve the sensitivity or accuracy in identifying symptomatic cases. Conclusions: The proton radiation dose response on FDG PET/CT imaging exhibited a predominantly linear dose response on modeling. Symptomatic patients had a higher dose response slope

Comparison of therapeutic dosimetric data from passively scattered proton and photon craniospinal irradiations for medulloblastoma

Directory of Open Access Journals (Sweden)

Howell Rebecca M

2012-07-01

Full Text Available Abstract Background For many decades, the standard of care radiotherapy regimen for medulloblastoma has been photon (megavoltage x-rays craniospinal irradiation (CSI. The late effects associated with CSI are well-documented in the literature and are in-part attributed to unwanted dose to healthy tissue. Recently, there is growing interest in using proton therapy for CSI in pediatric and adolescent patients to reduce this undesirable dose. Previous comparisons of dose to target and non-target organs from conventional photon CSI and passively scattered proton CSI have been limited to small populations (n ≤ 3 and have not considered the use of age-dependent target volumes in proton CSI. Methods Standard of care treatment plans were developed for both photon and proton CSI for 18 patients. This cohort included both male and female medulloblastoma patients whose ages, heights, and weights spanned a clinically relevant and representative spectrum (age 2–16, BMI 16.4–37.9 kg/m2. Differences in plans were evaluated using Wilcoxon signed rank tests for various dosimetric parameters for the target volumes and normal tissue. Results Proton CSI improved normal tissue sparing while also providing more homogeneous target coverage than photon CSI for patients across a wide age and BMI spectrum. Of the 24 parameters (V5, V10, V15, and V20 in the esophagus, heart, liver, thyroid, kidneys, and lungs Wilcoxon signed rank test results indicated 20 were significantly higher for photon CSI compared to proton CSI (p ≤ 0.05 . Specifically, V15 and V20 in all six organs and V5, V10 in the esophagus, heart, liver, and thyroid were significantly higher with photon CSI. Conclusions Our patient cohort is the largest, to date, in which CSI with proton and photon therapies have been compared. This work adds to the body of literature that proton CSI reduces dose to normal tissue compared to photon CSI for pediatric patients who are at substantial risk for

Comparison of therapeutic dosimetric data from passively scattered proton and photon craniospinal irradiations for medulloblastoma

International Nuclear Information System (INIS)

Howell, Rebecca M; Giebeler, Annelise; Koontz-Raisig, Wendi; Mahajan, Anita; Etzel, Carol J; D’Amelio, Anthony M Jr; Homann, Kenneth L

2012-01-01

For many decades, the standard of care radiotherapy regimen for medulloblastoma has been photon (megavoltage x-rays) craniospinal irradiation (CSI). The late effects associated with CSI are well-documented in the literature and are in-part attributed to unwanted dose to healthy tissue. Recently, there is growing interest in using proton therapy for CSI in pediatric and adolescent patients to reduce this undesirable dose. Previous comparisons of dose to target and non-target organs from conventional photon CSI and passively scattered proton CSI have been limited to small populations (n ≤ 3) and have not considered the use of age-dependent target volumes in proton CSI. Standard of care treatment plans were developed for both photon and proton CSI for 18 patients. This cohort included both male and female medulloblastoma patients whose ages, heights, and weights spanned a clinically relevant and representative spectrum (age 2–16, BMI 16.4–37.9 kg/m2). Differences in plans were evaluated using Wilcoxon signed rank tests for various dosimetric parameters for the target volumes and normal tissue. Proton CSI improved normal tissue sparing while also providing more homogeneous target coverage than photon CSI for patients across a wide age and BMI spectrum. Of the 24 parameters (V 5 , V 10 , V 15 , and V 20 in the esophagus, heart, liver, thyroid, kidneys, and lungs) Wilcoxon signed rank test results indicated 20 were significantly higher for photon CSI compared to proton CSI (p ≤ 0.05) . Specifically, V 15 and V 20 in all six organs and V 5 , V 10 in the esophagus, heart, liver, and thyroid were significantly higher with photon CSI. Our patient cohort is the largest, to date, in which CSI with proton and photon therapies have been compared. This work adds to the body of literature that proton CSI reduces dose to normal tissue compared to photon CSI for pediatric patients who are at substantial risk for developing radiogenic late effects. Although the present study

Dosimetric adaptive IMRT driven by fiducial points

International Nuclear Information System (INIS)

Crijns, Wouter; Van Herck, Hans; Defraene, Gilles; Van den Bergh, Laura; Haustermans, Karin; Slagmolen, Pieter; Maes, Frederik; Van den Heuvel, Frank

2014-01-01

Purpose: Intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy have become standard treatments but are more sensitive to anatomical variations than 3D conformal techniques. To correct for inter- and intrafraction anatomical variations, fast and easy to implement methods are needed. Here, the authors propose a full dosimetric IMRT correction that finds a compromise in-between basic repositioning (the current clinical practice) and full replanning. It simplifies replanning by avoiding a recontouring step and a full dose calculation. It surpasses repositioning by updating the preoptimized fluence and monitor units (MU) using a limited number of fiducial points and a pretreatment (CB)CT. To adapt the fluence the fiducial points were projected in the beam's eye view (BEV). To adapt the MUs, point dose calculation towards the same fiducial points were performed. The proposed method is intrinsically fast and robust, and simple to understand for operators, because of the use of only four fiducial points and the beam data based point dose calculations. Methods: To perform our dosimetric adaptation, two fluence corrections in the BEV are combined with two MU correction steps along the beam's path. (1) A transformation of the fluence map such that it is realigned with the current target geometry. (2) A correction for an unintended scaling of the penumbra margin when the treatment beams scale to the current target size. (3) A correction for the target depth relative to the body contour and (4) a correction for the target distance to the source. The impact of the correction strategy and its individual components was evaluated by simulations on a virtual prostate phantom. This heterogeneous reference phantom was systematically subjected to population based prostate transformations to simulate interfraction variations. Additionally, a patient example illustrated the clinical practice. The correction strategy was evaluated using both dosimetric

Dosimetric adaptive IMRT driven by fiducial points

Energy Technology Data Exchange (ETDEWEB)

Crijns, Wouter, E-mail: wouter.crijns@uzleuven.be [Department of Oncology, Laboratory of Experimental Radiotherapy, KU Leuven, Herestraat 49, 3000 Leuven, Belgium and Medical Imaging Research Center, KU Leuven, Herestraat 49, 3000 Leuven (Belgium); Van Herck, Hans [Medical Imaging Research Center, KU Leuven, Herestraat 49, 3000 Leuven, Belgium and Department of Electrical Engineering (ESAT) – PSI, Center for the Processing of Speech and Images, KU Leuven, 3000 Leuven (Belgium); Defraene, Gilles; Van den Bergh, Laura; Haustermans, Karin [Department of Oncology, Laboratory of Experimental Radiotherapy, KU Leuven, Herestraat 49, 3000 Leuven (Belgium); Slagmolen, Pieter [Medical Imaging Research Center, KU Leuven, Herestraat 49, 3000 Leuven (Belgium); Department of Electrical Engineering (ESAT) – PSI, Center for the Processing of Speech and Images, KU Leuven, 3000 Leuven (Belgium); iMinds-KU Leuven Medical IT Department, KU Leuven, 3000 Leuven (Belgium); Maes, Frederik [Medical Imaging Research Center, KU Leuven, Herestraat 49, 3000 Leuven (Belgium); Department of Electrical Engineering (ESAT) – PSI, Center for the Processing of Speech and Images, KU Leuven and iMinds, 3000 Leuven (Belgium); Van den Heuvel, Frank [Department of Oncology, Laboratory of Experimental Radiotherapy, KU Leuven, Herestraat 49, 3000 Leuven, Belgium and Department of Oncology, MRC-CR-UK Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford OX1 2JD (United Kingdom)

2014-06-15

Purpose: Intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy have become standard treatments but are more sensitive to anatomical variations than 3D conformal techniques. To correct for inter- and intrafraction anatomical variations, fast and easy to implement methods are needed. Here, the authors propose a full dosimetric IMRT correction that finds a compromise in-between basic repositioning (the current clinical practice) and full replanning. It simplifies replanning by avoiding a recontouring step and a full dose calculation. It surpasses repositioning by updating the preoptimized fluence and monitor units (MU) using a limited number of fiducial points and a pretreatment (CB)CT. To adapt the fluence the fiducial points were projected in the beam's eye view (BEV). To adapt the MUs, point dose calculation towards the same fiducial points were performed. The proposed method is intrinsically fast and robust, and simple to understand for operators, because of the use of only four fiducial points and the beam data based point dose calculations. Methods: To perform our dosimetric adaptation, two fluence corrections in the BEV are combined with two MU correction steps along the beam's path. (1) A transformation of the fluence map such that it is realigned with the current target geometry. (2) A correction for an unintended scaling of the penumbra margin when the treatment beams scale to the current target size. (3) A correction for the target depth relative to the body contour and (4) a correction for the target distance to the source. The impact of the correction strategy and its individual components was evaluated by simulations on a virtual prostate phantom. This heterogeneous reference phantom was systematically subjected to population based prostate transformations to simulate interfraction variations. Additionally, a patient example illustrated the clinical practice. The correction strategy was evaluated using both dosimetric

Basic Principles and Practices of Integrated Dosimetric Passportization of the Settlements in Ukraine.

Science.gov (United States)

Likhtarov, I A; Kovgan, L M; Masiuk, S V; Ivanova, O M; Chepurny, M I; Boyko, Z N; Gerasymenko, V B

2015-12-01

The purpose of the review is to demonstrate the results of dosimetric passportization (performed in 1991-2014) for the settlements of Ukraine which suffered from radioactive contamination caused by the Chornobyl accident. The dosimetric passportization played a key role in the National program on the liquidation of aftermath of the Chornobyl accident directed on recovery through all stages of the current radiation situation control and decision support touching upon various types of interventions and social benefits to the population of radioactively contaminated areas. The works being performed under dosimetric passportization did not have analogues among the researches which took place after other large-scale industrial and municipal accidents as well their scales as the duration of both radio-ecological and dosimetric monitoring.The new methodological approaches to the assessment of so-called passport doses of a settlement as well as to the definition of the concept of annual dose being the dose used to make decisions for providing both direct and indirect emergency countermeasures for the settlements of Ukraine became pioneering ones. During all the post-accident period there were issued sixteen collections of general dosimetric passportization data which accumulate the results of hundreds of thousands spectrometric, radiochemical and radiation levels measurements and WBC measurements carried out in 1991-2014.The annual passport doses calculated on the basis of these measurements (including their components) are unique information that quantifies the level and time dynamics of the radiation situation for each of the 2161 settlements of 74 raions in 12 oblasts during all the post-accident period. Thanks to the works of dosimetric passportization of the settlements of Ukraine there were created databases to be unique in their structure and content with quantitative characteristics of the territorial and temporal distribution, the dynamics of changes of a number

Dose distribution in the area of the operative cicatrice and the problem of local reccurences during postoperative external beam gamma therapy of breast cancer

International Nuclear Information System (INIS)

Todorov, Y.; Ivanova, K.; Penchev, V.

1982-01-01

Five-year experience is recorded with treatment of 503 patients with breast cancer, who received postoperative external beam gamma therapy, and the developement of local reccurences. Results are reported of dosimetric studies in the irradiated area, especially the thoracic wall, where total focal doses of 50 had been realized. The clinical results of treatment are discussed on this basis. Comparison is made with data available in the literature on the incidence, localization and time of development of local reccurences and the methods of treatment of the basic disease. The need of postoperative radiation treatment, particularly in the later stages of the disease, is pointed out. (authors)

SU-C-210-05: Evaluation of Robustness: Dosimetric Effects of Anatomical Changes During Fractionated Radiation Treatment of Pancreatic Cancer Patients

Energy Technology Data Exchange (ETDEWEB)

Horst, A van der; Houweling, A C; Bijveld, M M C; Visser, J; Bel, A [Academic Medical Center, Amsterdam, Noord-Holland (Netherlands)

2015-06-15

Purpose: Pancreatic tumors show large interfractional position variations. In addition, changes in gastrointestinal air volume and body contour take place during treatment. We aim to investigate the robustness of the clinical treatment plans by quantifying the dosimetric effects of these anatomical changes. Methods: Calculations were performed for up to now 3 pancreatic cancer patients who had intratumoral fiducials for daily CBCT-based positioning during their 3-week treatment. For each patient, deformable image registration of the planning CT was used to assign Hounsfield Units to each of the 13—15 CBCTs; air volumes and body contour were copied from CBCT. The clinical treatment plan was used (CTV-PTV margin = 10 mm; 36Gy; 10MV; 1 arc VMAT). Fraction dose distributions were calculated and accumulated. The V95% of the clinical target volume (CTV) and planning target volume (PTV) were analyzed, as well as the dose to stomach, duodenum and liver. Dose accumulation was done for patient positioning based on the fiducials (as clinically used) as well as for positioning based on bony anatomy. Results: For all three patients, the V95% of the CTV remained 100%, for both fiducial- and bony anatomy-based positioning. For fiducial-based positioning, dose to duodenum en stomach showed no discernable differences with planned dose. For bony anatomy-based positioning, the PTV V95% of the patient with the largest systematic difference in tumor position (patient 1) decreased to 85%; the liver Dmax increased from 33.5Gy (planned) to 35.5Gy. Conclusion: When using intratumoral fiducials, CTV dose coverage was only mildly affected by the daily anatomical changes. When using bony anatomy for patient positioning, we found a decline in PTV dose coverage due to the interfractional tumor position variations. Photon irradiation treatment plans for pancreatic tumors are robust to variations in body contour and gastrointestinal gas, but the use of fiducial-based daily position verification

The dosimetric effects of photon energy on the quality of prostate volumetric modulated arc therapy.

Science.gov (United States)

Mattes, Malcolm D; Tai, Cyril; Lee, Alvin; Ashamalla, Hani; Ikoro, N C

2014-01-01

Studies comparing the dosimetric effects of high- and low-energy photons to treat prostate cancer using 3-dimensional conformal and intensity modulated radiation therapy have yielded mixed results. With the advent of newer radiation delivery systems like volumetric modulated arc therapy (VMAT), the impact of changing photon energy is readdressed. Sixty-five patients treated for prostate cancer at our institution from 2011 to 2012 underwent CT simulation. A target volume encompassing the prostate and entire seminal vesicles was treated to 50.4 Gy, followed by a boost to the prostate and proximal seminal vesicles to a total dose of 81 Gy. The VMAT plans were generated for 6-MV and 10-MV photons under identical optimization conditions using the Eclipse system version 8.6 (Varian Medical Systems, Palo Alto, CA). The analytical anisotropic algorithm was used for all dose calculations. Plans were normalized such that 98% of the planning target volume (PTV) received 100% of the prescribed dose. Dose-volumetric data from the treatment planning system was recorded for both 6-MV and 10-MV plans, which were compared for both the entire cohort and subsets of patients stratified according to the anterior-posterior separation. Plans using 10-MV photons had statistically significantly lower relative integral dose (4.1%), gradient measure (4.1%), skin Dmax (16.9%), monitor units (13.0%), and bladder V(30) (3.1%) than plans using 6-MV photons (P photons was more pronounced for thicker patients (anterior-posterior separation >21 cm) for most parameters, with statistically significant differences in bladder V(30), bladder V(65), integral dose, conformity index, and monitor units. The main dosimetric benefits of 10-MV as compared with 6-MV photons are seen in thicker patients, though for the entire cohort 10-MV plans resulted in a lower integral dose, gradient measure, skin Dmax, monitor units, and bladder V(30), possibly at the expense of higher rectum V(81). Copyright © 2014

SU-F-T-443: Quantification of Dosimetric Effects of Dental Metallic Implant On VMAT Plans

Energy Technology Data Exchange (ETDEWEB)

Lin, C; Jiang, W [East Carolina University, Greenville, NC (United States); Feng, Y [East Carolina University (United States); Huang, Z [East Carolina University, Greenville, North Carolina (United States)

2016-06-15

Purpose: To evaluate the dosimetric impact of metallic implant that correlates with the size of targets and metallic implants and distance in between on volumetric-modulated arc therapy (VMAT) plans for head and neck (H&N) cancer patients with dental metallic implant. Methods: CT images of H&N cancer patients with dental metallic implant were used. Target volumes with different sizes and locations were contoured. Metal artifact regions excluding surrounding critical organs were outlined and assigned with CT numbers close to water (0HU). VMAT plans with half-arc, one-full-arc and two-full-arcs were constructed and same plans were applied to structure sets with and without CT number assignment of metal artifact regions and compared. D95% was utilized to investigate PTV dose coverage and SNC Patient− Software was used for the analysis of dose distribution difference slice by slice. Results: For different targets sizes, variation of PTV dose coverage (Delta-D95%) with and without CT number replacement reduced with larger target volume for all half-arc, one-arc and two-arc VMAT plans even though there were no clinically significant differences. Additionally, there were no significant variations of the maximum percent difference (max.%diff) of dose distribution. With regard to the target location, Delta-D95% and max. %diff dropped with increasing distance between target and metallic implant. Furthermore, half-arc plans showed greater impact than one-arc plans, and two-arc plans had smallest influence for PTV dose coverage and dose distribution. Conclusion: The target size has less correlation of doseimetric impact than the target location relative to metallic implants. Plans with more arcs alleviate the dosimetric effect of metal artifact because of less contribution to the target dose from beams going through the regions with metallic artifacts. Incorrect CT number causes inaccurate dose distribution, therefore appropriately overwriting metallic artifact regions with

SU-F-T-443: Quantification of Dosimetric Effects of Dental Metallic Implant On VMAT Plans

International Nuclear Information System (INIS)

Lin, C; Jiang, W; Feng, Y; Huang, Z

2016-01-01

Purpose: To evaluate the dosimetric impact of metallic implant that correlates with the size of targets and metallic implants and distance in between on volumetric-modulated arc therapy (VMAT) plans for head and neck (H&N) cancer patients with dental metallic implant. Methods: CT images of H&N cancer patients with dental metallic implant were used. Target volumes with different sizes and locations were contoured. Metal artifact regions excluding surrounding critical organs were outlined and assigned with CT numbers close to water (0HU). VMAT plans with half-arc, one-full-arc and two-full-arcs were constructed and same plans were applied to structure sets with and without CT number assignment of metal artifact regions and compared. D95% was utilized to investigate PTV dose coverage and SNC Patient− Software was used for the analysis of dose distribution difference slice by slice. Results: For different targets sizes, variation of PTV dose coverage (Delta_D95%) with and without CT number replacement reduced with larger target volume for all half-arc, one-arc and two-arc VMAT plans even though there were no clinically significant differences. Additionally, there were no significant variations of the maximum percent difference (max.%diff) of dose distribution. With regard to the target location, Delta_D95% and max. %diff dropped with increasing distance between target and metallic implant. Furthermore, half-arc plans showed greater impact than one-arc plans, and two-arc plans had smallest influence for PTV dose coverage and dose distribution. Conclusion: The target size has less correlation of doseimetric impact than the target location relative to metallic implants. Plans with more arcs alleviate the dosimetric effect of metal artifact because of less contribution to the target dose from beams going through the regions with metallic artifacts. Incorrect CT number causes inaccurate dose distribution, therefore appropriately overwriting metallic artifact regions with

Dosimetric properties of carbon loaded LiF detectors for beta photon extremity dosimetry

International Nuclear Information System (INIS)

Burgkhardt, B.; Klipfel, A.

1990-01-01

The dosimetric properties of carbon loaded LiF detectors manufactured by Alnor and Vinten are presented in comparison with various LiF detectors. In particular, the beta and photon response, the residual reading after repeated annealing in the oven or reader as well as light sensitivity and fading are discussed. In comparison with LiF detectors of 240 mg.cm -2 , LiF + C detectors indicate a photon response of only 2% and in finger rings irradiated on a finger phantom an unexpected high photon energy response. Regarding repeated use, oven annealing in air or N 2 affects mainly Vinten LiF + 1% C by discoloration and reduces the 147 Pm response of LiF + C detectors by between 1% and 6% per N 2 annealing, whereas reader annealing in the Toledo and Alnor reader does not affect the relative beta response. The residual dose H 0 of LiF + C remains sufficiently low after oven annealing, but increases for Alnor LiF + 4% C after reader annealing, which is therefore more suitable for Vinten LiF + 1% C. Spurious detector reading exceeds H 0 and its standard deviation by a factor of 2 to 3. (author)

Dosimetric response of united, commercially available CTA foils for 60Co gamma rays

International Nuclear Information System (INIS)

Peimel-Stuglik, Z.

2001-01-01

The usefulness of two kinds of untinted CTA foils: Fuji CTR-125 dosimetric foil and technical CTA-T foil, produced by 'Zaklady Chemiczne, 'Gorzow Wielkopolski' as support for light-sensitive layers of amateur photo-films, for 60 Co gamma ray dosimetry was investigated. In spite of rather bad physical parameters of the technical foil (spread of foil thickness, high and different initial absorbance) the dosimetric response of both foils for 60 Co gamma rays was similar. The CTA-T foil can be used for routine dosimetry providing that dosimetric signals have to be calculated exactly as recommended by the ASTM (American Society for Testing and Materials) standard, i.e. as the difference of absorbance of irradiated and (the same) non-irradiated foil. Any other approach may lead to high errors of dose evaluation. The last is true also for other CTA foils, especially after long self-life. (author)

Dosimetric optimization of worksite involving the installation of VATS containing highly active effluent

International Nuclear Information System (INIS)

Legee, F.; Busani, J.; Madigand, Y.; Pailloux, J.

1996-01-01

Within the framework of safety improvements at the CEA, CEA-FAR, concerned to formalize the ALARA initiative, has carried out for information and training purpose and to create awareness a dosimetric assessment of the worksite where new storage vats for highly active effluents are to be installed. The approach used for this worksite is global. Techniques used were all complementary, ensuring constant elaboration, experiment follow-up and feedback of a worksite at a relatively low dosimetric cost (an estimated 36 men.mSv brought down to 30 men.mSv through implementation of the ALARA principle). This type of global conception of radioprotection involving all the employees (head of project, project managers, companies, radioprotection employees...) which today proves its worth on a modest worksite must now be extended to worksites of a broader scope (several hundreds of men.mSv) where fulfillment of the dosimetric objectives is a major stake. (author)

Dosimetric Coverage of the Prostate, Normal Tissue Sparing, and Acute Toxicity with High-Dose-Rate Brachytherapy for Large Prostate Volumes

Directory of Open Access Journals (Sweden)

George Yang

2015-06-01

Full Text Available ABSTRACTPurposeTo evaluate dosimetric coverage of the prostate, normal tissue sparing, and acute toxicity with HDR brachytherapy for large prostate volumes.Materials and MethodsOne hundred and two prostate cancer patients with prostate volumes >50 mL (range: 5-29 mL were treated with high-dose-rate (HDR brachytherapy ± intensity modulated radiation therapy (IMRT to 4,500 cGy in 25 daily fractions between 2009 and 2013. HDR brachytherapy monotherapy doses consisted of two 1,350-1,400 cGy fractions separated by 2-3 weeks, and HDR brachytherapy boost doses consisted of two 950-1,150 cGy fractions separated by 4 weeks. Twelve of 32 (38% unfavorable intermediate risk, high risk, and very high risk patients received androgen deprivation therapy. Acute toxicity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE version 4.ResultsMedian follow-up was 14 months. Dosimetric goals were achieved in over 90% of cases. Three of 102 (3% patients developed Grade 2 acute proctitis. No variables were significantly associated with Grade 2 acute proctitis. Seventeen of 102 (17% patients developed Grade 2 acute urinary retention. American Urological Association (AUA symptom score was the only variable significantly associated with Grade 2 acute urinary retention (p=0.04. There was no ≥ Grade 3 acute toxicity.ConclusionsDosimetric coverage of the prostate and normal tissue sparing were adequate in patients with prostate volumes >50 mL. Higher pre-treatment AUA symptom scores increased the relative risk of Grade 2 acute urinary retention. However, the overall incidence of acute toxicity was acceptable in patients with large prostate volumes.

Dosimetric coverage of the prostate, normal tissue sparing, and acute toxicity with high-dose-rate brachytherapy for large prostate volumes

Energy Technology Data Exchange (ETDEWEB)

Yang, George; Strom, Tobin J.; Shrinath, Kushagra; Mellon, Eric A.; Fernandez, Daniel C.; Biagioli, Matthew C. [Department of Radiation Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL (United States); Wilder, Richard B., E-mail: mcbiagioli@yahoo.com [Cancer Treatment Centers of America, Newnan, GA (United States)

2015-05-15

Purpose: to evaluate dosimetric coverage of the prostate, normal tissue sparing, and acute toxicity with HDR brachytherapy for large prostate volumes. Materials and methods: one hundred and two prostate cancer patients with prostate volumes >50 mL (range: 5-29 mL) were treated with high-dose-rate (HDR) brachytherapy ± intensity modulated radiation therapy (IMRT) to 4,500 cGy in 25 daily fractions between 2009 and 2013. HDR brachytherapy monotherapy doses consisted of two 1,350-1,400 cGy fractions separated by 2-3 weeks, and HDR brachytherapy boost doses consisted of two 950-1,150 cGy fractions separated by 4 weeks. Twelve of 32 (38%) unfavorable intermediate risk, high risk, and very high risk patients received androgen deprivation therapy. Acute toxicity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE) version 4. Results: median follow-up was 14 months. Dosimetric goals were achieved in over 90% of cases. Three of 102 (3%) patients developed Grade 2 acute proctitis. No variables were significantly associated with Grade 2 acute proctitis. Seventeen of 102 (17%) patients developed Grade 2 acute urinary retention. American Urological Association (AUA) symptom score was the only variable significantly associated with Grade 2 acute urinary retention (p-0.04). There was no ≥ Grade 3 acute toxicity. Conclusions: dosimetric coverage of the prostate and normal tissue sparing were adequate in patients with prostate volumes >50 mL. Higher pre-treatment AUA symptom scores increased the relative risk of Grade 2 acute urinary retention. However, the overall incidence of acute toxicity was acceptable in patients with large prostate volumes. (author)

SU-D-204-04: Correlations Between Dosimetric Indices and Follow-Up Data for Salivary Glands Six Months After Radiation Therapy for Head and Neck Cancer

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Chera, B; Price, A; Kostich, M; Green, R; Das, S; Mavroidis, P [University of North Carolina, Chapel Hill, North Carolina (United States); Amdur, R; Mendenhall, W [University of Florida, Gainesville, FL (United States); Sheets, N [University of North Carolina, Raleigh, North Carolina (United States); Marks, L [UNC School of Medicine, Chapel Hill, NC (United States)

2016-06-15

Purpose: To investigate the correlation between different dosimetric indices of salivary glands (as separate or combined structures) to patient-reported dry mouth 6 months post radiotherapy using the novel patient reported outcome version of the CTCAE (PRO-CTCAE). Methods: Forty-three patients with oropharyngeal squamous cell carcinoma were treated on a prospective multi-institutional study. All patients received de-intensified 60 Gy intensity modulated radiotherapy. Dosimetric constraints were used for the salivary glands (e.g. mean dose to the contralateral-parotid < 26 Gy). We investigated correlations of individual patient dosimetric data of the parotid and submandibular glands (as separate or combined structures) to their self-reported 6 month post-treatment dry mouth responses. Moderate dry mouth responses were most prevalent and were used as the clinical endpoint indicating response. The correlation of Dmean, Dmax and a range of dosevolume (VD) points were assessed through the area under the Receiver Operating Characteristic curve (ROC) and Odds Ratios (OR). Results: Patients reporting non/mild dry mouth response (N=22) had average Dmean = 19.6 ± 6.2Gy to the contralateral-parotid compared to an average Dmean = 28.0 ± 8.3Gy and an AUC = 0.758 for the patients reporting moderate/severe/very severe dry mouth (N=21). Analysis of the range of VD’s for patients who had reported dry mouth showed that for the contralateral-parotid the indices V18 through V22 had the highest area under the curves (AUC) (0.762 – 0.772) compared to a more traditional dosimetric index V30, which had an AUC = 0.732. The highest AUC was observed for the combination of contralateral parotid and contralateral submandibular glands, for which V16 through V28 had AUC = 0.801 – 0.834. Conclusion: Patients who report moderate/severe/very severe dry mouth 6 months post radiotherapy had on average higher Dmean. The V16-V28 of the combination of the contralateral glands showed the highest

Simulation of The ICRP-30 Dosimetric Model for the Respiratory Tract

International Nuclear Information System (INIS)

Giaddui, T.; Atia, M. A.

2004-01-01

Matlab was used to write a simulation program (ACID1) to simulate the ICRP-30 dosimetric model for the respiratory tract. The program (a new version of the one presented at the sixth Arab conference held in Cairo 2002) calculates a series of dosimetric quantities for the reference man as a result of the inhalation of any radionuclide. The program also plots the variation of activity with time for all organs and provided with a graphical user interface to make it friendly user. The results obtained by this program was compared with similar results obtained by other source and found to be very close. (Authors)

Study of dosimetric effects due to metallic heterogeneity of tissue expanders in post-mastectomy radiotherapy

International Nuclear Information System (INIS)

Trombetta, Debora M.; Silva, Ademir X. da; Rosa, Luiz A.R. da

2009-01-01

Breast cancer is the most common cancer among women. In each year approximately 20% of the new cases of cancer in women are breast cancers. Despite the increase in the use of breast-conserving treatment, some women still require mastectomy as their primary surgical management. A large part of these women, whom undergo a mastectomy, realize a breast reconstruction afterwards. The most common options for reconstruction include autogenous tissue techniques and tissue expansion followed by breast implant placement. Many trials have demonstrated a survival benefit associated with post-mastectomy radiotherapy mainly if the treatment starts right after the mastectomy. In such case patients whom were realizing the breast reconstruction using tissue expanders can be irradiated using this. These patients posses a material with high atomic number within the irradiated area, so this metallic port becomes an heterogeneity which can modify the calculated doses distribution for the treatment. The study was due through the quantification of the relative transmission of 6MV and 15MV radiotherapy beam, making use of computer simulations with Monte Carlo method implemented by the MCNPX code. The results show that the presence of this metallic heterogeneity changes the transmission of the beam, causing a reduction up to 13% in the geometric shadowed region. According to dosimetric protocols, which recommend that the reduction in the dose should be bellow of 5%, the difference found in the study could be significant. (author)

Dosimetric impact of interplay effect in lung IMRT and VMAT treatment using in-house dynamic thorax phantom

International Nuclear Information System (INIS)

Mukhlisin; Pawiro, S A

2016-01-01

Tumor motion due to patient's respiratory is a significant problem in radiotherapy treatment of lung cancer. The purpose of this project is to study the interplay effect through dosimetry verification between the calculated and delivered dose, as well as the dosimetric impact of leaf interplay with breathing-induced tumor motion in IMRT and VMAT treatment. In this study, a dynamic thorax phantom was designed and constructed for dosimetry measurement. The phantom had a linear sinusoidal tumor motion toward superior-inferior direction with variation of amplitudes and periods. TLD-100 LiF:Mg,Ti and Gafchromic EBT2 film were used to measure dose in the midpoint target and the spinal cord. The IMRT and VMAT treatment had prescription dose of 200 cGy per fraction. The dosimetric impact due to interplay effect during IMRT and VMAT treatment were resulted in the range of 0.5% to -6.6% and 0.9% to -5.3% of target dose reduction, respectively. Meanwhile, mean dose deviation of spinal cord in IMRT and VMAT treatment were around 1.0% to -6.9% and 0.9% to -6.3%, respectively. The results showed that if respiratory management technique were not implemented, the presence of lung tumor motion during dose delivery in IMRT and VMAT treatment causes dose discrepancies inside tumor volume. (paper)

Comparative Toxicity and Dosimetric Profile of Whole-Pelvis Versus Prostate Bed-Only Intensity-Modulated Radiation Therapy After Prostatectomy

Energy Technology Data Exchange (ETDEWEB)

Deville, Curtiland, E-mail: deville@uphs.upenn.edu [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Vapiwala, Neha [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Hwang, Wei-Ting [Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Lin Haibo; Bar Ad, Voichita; Tochner, Zelig; Both, Stefan [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States)

2012-03-15

Purpose: To assess whether whole-pelvis (WP) intensity modulated radiation therapy (IMRT) for prostate cancer (PCa) after prostatectomy is associated with increased toxicity compared to prostate-bed only (PB) IMRT. Methods and Materials: All patients (n = 67) undergoing postprostatectomy IMRT to 70.2 Gy at our institution from January 2006 to January 2009 with minimum 12-month follow-up were divided into WP (n = 36) and PB (n = 31) comparison groups. WP patients received initial pelvic nodal IMRT to 45 Gy. Pretreatment demographics, bladder and rectal dose-volume histograms, and maximum genitourinary (GU) and gastrointestinal (GI) toxicities were compared. Logistic regression models evaluated uni- and multivariate associations between pretreatment demographics and toxicities. Results: Pretreatment demographics including age and comorbidities were similar between groups. WP patients had higher Gleason scores, T stages, and preoperative prostate-specific antigen (PSA) levels, and more WP patients underwent androgen deprivation therapy (ADT). WP minimum (Dmin) and mean bladder doses, bladder volumes receiving more than 5 Gy (V5) and V20, rectal Dmin, and PB bladder and rectal V65 were significantly increased. Maximum acute GI toxicity was Grade 2 and was increased for WP (61%) vs. PB (29%) patients (p = 0.001); there was no significant difference in acute Grade {>=}2 GU toxicity (22% WP vs. 10% PB; p = 0.193), late Grade {>=}2 GI toxicity (3% WP vs. 0% PB; p = 0.678), or late Grade {>=}2 GU toxicity (28% WP vs. 19% PB; p = 0.274) with 25-month median follow-up (range, 12-44 months). On multivariate analysis, long-term ADT use was associated with Grade {>=}2 late GU toxicity (p = 0.02). Conclusion: Despite dosimetric differences in irradiated bowel, bladder, and rectum, WP IMRT resulted only in clinically significant increased acute GI toxicity in comparison to that with PB IMRT, with no differences in GU or late GI toxicity.

Dosimetric comparison in a cancer of the Cervix with different therapeutic modalities; Comparacion dosimetrica en un cancer de Cervix con distintas modalidades terapeuticas

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Alonso Iracheta, L.; Casa de Julian, M. A. de la; Samper Ots, P.; Penas Cabrera, M. D. de las; Jimenez Gonzalez, J. M.

2013-07-01

Cervical cancer is usually treated with radiotherapy composed of 3D (RC3D) and supine position, and is usually not usually outline the small intestine in cases of exclusively pelvic irradiation. In our Center we wanted to check what dose receives the small intestine in these cases and if the positioning of the patient or used irradiation technique influence the distribution of the histogram dose-volume. (Author)

SU-F-T-107: Correlations Between Dosimetric Indices of Pharyngeal Constrictors and Proximal Esophagus with Associated Patient-Reported Outcomes Six Months After Radiation Therapy for Head and Neck Cancer

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Chera, B; Price, A; Kostich, M; Green, R; Das, S; Mavroidis, P [University of North Carolina, Chapel Hill, North Carolina (United States); Amdur, R; Mendenhall, W [University of Florida, Gainesville, FL (United States); Sheets, N [University of North Carolina, Raleigh, North Carolina (United States); Marks, L [UNC School of Medicine, Chapel Hill, NC (United States)

2016-06-15

Purpose: To compare the correlations between different dosimetric indices derived from the pharyngeal constrictor muscles and proximal esophagus with patient-reported difficulty in swallowing 6 months post radiotherapy using a novel patient reported outcome version of CTCAE (PRO-CTCAE). Methods: Forty-three patients with oropharyngeal squamous cell carcinoma were treated on a prospective multi-institutional study. All patients received de-intensified 60 Gy intensity modulated radiotherapy. We investigated correlations of individual patient dosimetric data of the superior (SPC), middle (MPC), inferior (IPC) pharyngeal constrictor muscles, the superior esophagus (SES), and the inferior esophagus (IES) to their self-reported 6 month post-treatment swallowing difficulty responses. Mild (≥ Grade 1) swallowing difficulty responses were used as the clinical endpoint indicating response. The predictive efficacy of Dmean and dose-volume (VD) points were assessed through the area under the Receiver Operating Characteristic curve (ROC) and Odds Ratio (OR). Results: The SES and SPC had more favorable area under the curves (AUC) for the Dmean (0.62 and 0.70) while the Dmean to the IPC, MPC, and IES produced suboptimal AUCs (0.42, 0.48, and 0.52). Additionally, over the range of VD, the V54 and V55 for the SES and SPC demonstrated the highest AUCs: AUC(SES) = 0.76–0.73 and AUC(SPC) = 0.72–0.69, respectively. The IES, IPC, and MPC had worse AUC results over the range of VD. An optimal OR can be found when V54 = 96% for the SPC, where OR = 3.96 (1.07–14.62). Conclusion: The V45 and V55 of the SES and SPC had the highest correlation to the clinical endpoint compared to the commonly used dosimetric index, Dmean for both the esophagus and constrictor muscles. The reported dosimetric data demonstrates that new dosimetric indices may need to be considered in the setting of dose de-escalation and self-reported outcomes.

Dosimetric calculation of I-131 activity for the treatment to patients having differentiated thyroid cancer. Benefits and limitations; Calculo dosimetrico de la actividad de I-131 para tratamiento de pacientes con cancer diferenciado de tiroides (CADT). Beneficios y limitaciones

Energy Technology Data Exchange (ETDEWEB)

Cabrejas, R. C.; Chebel, G. M.; Fadel, A. M.; Rojo, A. M.; Deluca, G.; Degross, O. J.; Valdivieso, C. M.; Carbejas, M. L.

2006-07-01

Maximum safe activity calculation, that has to be administered for treatment to patients having Differentiated Thyroid Cancer (CADT). No important side effects should be produced. Post treatment evolution was analysed. 23 Dosimetric studies were performed determining blood and whole body uptake curves (CE)during 5 days. Using the MIRDOSE software, the maximum safe activity in the whole body (CE)was calculated. The retained activity in the body (AR), 48 hs. post tracer dose. Should have been less than 2.96 GBq so as to avoid lung fibrosis. 17 patients that received activities<11.1 GBq, had no side effects. Three patients presents special situations: high AR, users in the mouth, and plaque to and leucopenia. This methodology has benefits because AT can be estimated. This was possible for 85% of the patients. When AR was high at 48 hr, AT was diminished to avoid pulmonary lesions. Tumor absorbed dose estimation, will allow the administration of AT>11.1 GBq in the future. (Author)

Dosimetric evaluation of a novel high dose rate (HDR) intraluminal / interstitial brachytherapy applicator for gastrointestinal and bladder cancers

Science.gov (United States)

Aghamiri, Seyyed Mahmoud Reza; Najarian, Siamak; Jaberi, Ramin

2010-01-01

High dose rate (HDR) brachytherapy is one of the accepted treatment modalities in gastro‐intestinal tract and bladder carcinomas. Considering the shortcoming of contact brachytherapy routinely used in gastrointestinal tract in treatment of big tumors or invasive method of bladder treatment, an intraluminal applicator with the capability of insertion into the tumor depth seems to be useful. This study presents some dosimetric evaluations to introduce this applicator to the clinical use. The radiation attenuation characteristics of the applicator were evaluated by means of two dosimetric methods including well‐type chamber and radiochromic film. The proposed 110 cm long applicator has a flexible structure made of stainless steel for easy passage through lumens and a needle tip to drill into big tumors. The 2 mm diameter of the applicator is thick enough for source transition, while easy passage through any narrow lumen such as endoscope or cystoscope working channel is ensured. Well‐chamber results showed an acceptably low attenuation of this steel springy applicator. Performing absolute dosimetry resulted in a correlation coefficient of R=0.9916(p‐value≈10−7) between standard interstitial applicator and the one proposed in this article. This study not only introduces a novel applicator with acceptable attenuation but also proves the response independency of the GAFCHROMIC EBT films to energy. By applying the dose response of the applicator in the treatment planning software, it can be used as a new intraluminal / interstitial applicator. PACS number: 87.53.Bn, 87.53.Jw, 29.40.Cs

Dosimetric comparison between proton and photon beams in the moving gap region in cranio-spinal irradiation (CSI)

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Cheng, Chee-Wai; Das, Indra J.; Zhao, Li; Wolanski, Mark; Johnstone, Peter A.S.; Buchsbaum, Jeffrey C. [IU Health Proton Therapy Center, Bloomington (United States); Dept. of Radiation Oncology, Indiana Univ. School of Medicine, Indianapolis (United States)], e-mail: ccheng1@iuhealth.org; Srivastava, Shiv P. [Dept. of Radiation Oncology, Indiana Univ. School of Medicine, Indianapolis (United States); Dept. of Radiation Oncology, Reid Hospital, Richmond (United States); Simmons, Joseph [IU Health Proton Therapy Center, Bloomington (United States)

2013-04-15

Purpose: To investigate the moving gap region dosimetry in proton beam cranio-spinal irradiation (CSI) to provide optimal dose uniformity across the treatment volume. Material and methods: Proton beams of ranges 11.6 cm and 16 cm are used for the spine and the brain fields, respectively. Beam profiles for a 30 cm snout are first matched at the 50% level (hot match) on the computer. Feathering is simulated by shifting the dose profiles by a known distance two successive times to simulate a 2 x feathering scheme. The process is repeated for 2 mm and 4 mm gaps. Similar procedures are used to determine the dose profiles in the moving gap for a series of gap widths, 0-10 mm, and feathering step sizes, 4-10 mm, for a Varian iX 6MV beam. The proton and photon dose profiles in the moving gap region are compared. Results: The dose profiles in the moving gap exhibit valleys and peaks in both proton and photon beam CSI. The dose in the moving gap for protons is around 100% or higher for 0 mm gap, for both 5 and 10 mm feathering step sizes. When the field gap is comparable or larger than the penumbra, dose minima as low as 66% is obtained. The dosimetric characteristics for 6 MV photon beams can be made similar to those of the protons by appropriately combining gap width and feathering step size. Conclusion: The dose in the moving gap region is determined by the lateral penumbras, the width of the gap and the feathering step size. The dose decreases with increasing gap width or decreasing feathering step size. The dosimetric characteristics are similar for photon and proton beams. However, proton CSI has virtually no exit dose and is beneficial for pediatric patients, whereas with photon beams the whole lung and abdomen receive non-negligible exit dose.

Can reduction of uncertainties in cervix cancer brachytherapy potentially improve clinical outcome?

DEFF Research Database (Denmark)

Nesvacil, Nicole; Tanderup, Kari; Lindegaard, Jacob C

2016-01-01

AIM: The aim of this study was to quantify the impact of different types and magnitudes of dosimetric uncertainties in cervix cancer brachytherapy (BT) on tumour control probability (TCP) and normal tissue complication probability (NTCP) curves. MATERIALS AND METHODS: A dose-response simulation...

Adaptation of the present concept of dosimetric radiation protection quantities for external radiation to radiation protection practice

International Nuclear Information System (INIS)

Boehm, J.; Thompson, I. M. G.

2004-01-01

The present concept of dosimetric radiation protection quantities for external radiation is reviewed. For everyday application of the concept some adaptations are recommended. The check of the compliance with dose limits should be performed either by the comparison with values of the respective operational quantities directly or by the calculation of the protection quantity by means of the operational quantity, the appertaining conversion coefficient and additional information of the radiation field. Only four operational quantities are regarded to be sufficient for most applications in radiation protection practice. The term equivalent should be used in the connection dose equivalent only. Proposals are made for names of frequently used operational quantities which are denoted up to now by symbols only. (authors)

Dosimetric methodology of the ICRP

International Nuclear Information System (INIS)

Eckerman, K.F.

1994-01-01

Establishment of guidance for the protection of workers and members of the public from radiation exposures necessitates estimation of the radiation dose to tissues of the body at risk. The dosimetric methodology formulated by the International Commission on Radiological Protection (ICRP) is intended to be responsive to this need. While developed for radiation protection, elements of the methodology are often applied in addressing other radiation issues; e.g., risk assessment. This chapter provides an overview of the methodology, discusses its recent extension to age-dependent considerations, and illustrates specific aspects of the methodology through a number of numerical examples

Model dosimetric for Radon and Daughters

International Nuclear Information System (INIS)

Puerta, J.A.; Cardenas, H.F.

1998-01-01

You elaborates a model dosimetric for radon and their products of decline of short half life starting from the new model of the breathing tract of the publication 66 of the ICRP and the use of the systemic models proposed in the publication 67, 68 and 69 of the same commission. The correlated used methodology the incorporation of these radionuclides with the activity in organs and you excrete, considering the difference of metabolic behavior of the products of decline and of their predecessor

Dosimetric analysis of BNCT - Boron Neutron Capture Therapy - coupled to 252Cf brachytherapy

International Nuclear Information System (INIS)

Brandao, Samia F.; Campos, Tarcisio P.R.

2009-01-01

The incidence of brain tumors is increasing in world population; however, the treatments employed in this type of tumor have a high rate of failure and in some cases have been considered palliative, depending on histology and staging of tumor. Its necessary to achieve the control tumor dose without the spread irradiation cause damage in the brain, affecting patient neurological function. Stereotactic radiosurgery is a technique that achieves this; nevertheless, other techniques that can be used on the brain tumor control must be developed, in order to guarantee lower dose on health surroundings tissues other techniques must be developing. The 252 Cf brachytherapy applied to brain tumors has already been suggested, showing promising results in comparison to photon source, since the active source is placed into the tumor, providing greater dose deposition, while more distant regions are spared. BNCT - Boron Neutron Capture Therapy - is another technique that is in developing to brain tumors control, showing theoretical superiority on the rules of conventional treatments, due to a selective irradiation of neoplasics cells, after the patient receives a borate compound infusion and be subjected to a epithermal neutrons beam. This work presents dosimetric studies of the coupling techniques: BNCT with 252 Cf brachytherapy, conducted through computer simulation in MCNP5 code, using a precise and well discretized voxel model of human head, which was incorporated a representative Glioblastoma Multiform tumor. The dosimetric results from MCNP5 code were exported to SISCODES program, which generated isodose curves representing absorbed dose rate in the brain. Isodose curves, neutron fluency, and dose components from BNCT and 252 Cf brachytherapy are presented in this paper. (author)

The effects of pre-dose and annealing temperature on some dosimetric properties of thermoluminescence of quartz

International Nuclear Information System (INIS)

Lin Zhikai

1996-02-01

The following aspects of dosimetric properties of quartz sample were studied. (1) The changes in dosimetric sensitivity of quartz with different pre-doses under different annealing temperature; (2) the option of optimal annealing temperature which can make the dosimetric sensitivity of quartz to restore its original level; (3) The changes in dosimetric sensitivity of quartz with different annealing time at 500 degree C for 8 h; (4) Repeated experiments were carried out in order to prove whether the sensitivity of quartz can restore its original level at annealing temperature 700 degree C for 3 h. It has been found that at 700 degree C for 3 h gave the least sensitivity change and the sensitivity of quartz almost restored its original level. Repeated experiments with four kinds of quartz sample confirmed this conclusion. The dramatic change of TL glow curve occurred only at the condition of annealing temperature 900 degree C for 1 h. This result was different from that obtained by D. J. Huntley et al. (1988). (3 refs., 4 figs., 1 tab.)

A Comprehensive Comparison of IMRT and VMAT Plan Quality for Prostate Cancer Treatment

International Nuclear Information System (INIS)

Quan, Enzhuo M.; Li Xiaoqiang; Li Yupeng; Wang Xiaochun; Kudchadker, Rajat J.; Johnson, Jennifer L.; Kuban, Deborah A.; Lee, Andrew K.; Zhang Xiaodong

2012-01-01

Purpose: We performed a comprehensive comparative study of the plan quality between volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) for the treatment of prostate cancer. Methods and Materials: Eleven patients with prostate cancer treated at our institution were randomly selected for this study. For each patient, a VMAT plan and a series of IMRT plans using an increasing number of beams (8, 12, 16, 20, and 24 beams) were examined. All plans were generated using our in-house–developed automatic inverse planning (AIP) algorithm. An existing eight-beam clinical IMRT plan, which was used to treat the patient, was used as the reference plan. For each patient, all AIP-generated plans were optimized to achieve the same level of planning target volume (PTV) coverage as the reference plan. Plan quality was evaluated by measuring mean dose to and dose–volume statistics of the organs at risk, especially the rectum, from each type of plan. Results: For the same PTV coverage, the AIP-generated VMAT plans had significantly better plan quality in terms of rectum sparing than the eight-beam clinical and AIP-generated IMRT plans (p < 0.0001). However, the differences between the IMRT and VMAT plans in all the dosimetric indices decreased as the number of beams used in IMRT increased. IMRT plan quality was similar or superior to that of VMAT when the number of beams in IMRT was increased to a certain number, which ranged from 12 to 24 for the set of patients studied. The superior VMAT plan quality resulted in approximately 30% more monitor units than the eight-beam IMRT plans, but the delivery time was still less than 3 min. Conclusions: Considering the superior plan quality as well as the delivery efficiency of VMAT compared with that of IMRT, VMAT may be the preferred modality for treating prostate cancer.

Dose–Volume Effects on Patient-Reported Acute Gastrointestinal Symptoms During Chemoradiation Therapy for Rectal Cancer

International Nuclear Information System (INIS)

Chen, Ronald C.; Mamon, Harvey J.; Ancukiewicz, Marek; Killoran, Joseph H.; Crowley, Elizabeth M.; Blaszkowsky, Lawrence S.; Wo, Jennifer Y.; Ryan, David P.; Hong, Theodore S.

2012-01-01

Purpose: Research on patient-reported outcomes (PROs) in rectal cancer is limited. We examined whether dose–volume parameters of the small bowel and large bowel were associated with patient-reported gastrointestinal (GI) symptoms during 5-fluorouracil (5-FU)–based chemoradiation treatment for rectal cancer. Methods and Materials: 66 patients treated at the Brigham and Women’s Hospital or Massachusetts General Hospital between 2006 and 2008 were included. Weekly during treatment, patients completed a questionnaire assessing severity of diarrhea, urgency, pain, cramping, mucus, and tenesmus. The association between dosimetric parameters and changes in overall GI symptoms from baseline through treatment was examined by using Spearman’s correlation. Potential associations between these parameters and individual GI symptoms were also explored. Results: The amount of small bowel receiving at least 15 Gy (V15) was significantly associated with acute symptoms (p = 0.01), and other dosimetric parameters ranging from V5 to V45 also trended toward association. For the large bowel, correlations between dosimetric parameters and overall GI symptoms at the higher dose levels from V25 to V45 did not reach statistical significance (p = 0.1), and a significant association was seen with rectal pain from V15 to V45 (p < 0.01). Other individual symptoms did not correlate with small bowel or large bowel dosimetric parameters. Conclusions: The results of this study using PROs are consistent with prior studies with physician-assessed acute toxicity, and they identify small bowel V15 as an important predictor of acute GI symptoms during 5-FU–based chemoradiation treatment. A better understanding of the relationship between radiation dosimetric parameters and PROs may allow physicians to improve radiation planning to optimize patient outcomes.

Online dosimetric evaluation of larynx SBRT: A pilot study to assess the necessity of adaptive replanning.

Science.gov (United States)

Mao, Weihua; Rozario, Timothy; Lu, Weiguo; Gu, Xuejun; Yan, Yulong; Jia, Xun; Sumer, Baran; Schwartz, David L

2017-01-01

We have initiated a multi-institutional phase I trial of 5-fraction stereotactic body radiotherapy (SBRT) for Stage III-IVa laryngeal cancer. We conducted this pilot dosimetric study to confirm potential utility of online adaptive replanning to preserve treatment quality. We evaluated ten cases: five patients enrolled onto the current trial and five patients enrolled onto a separate phase I SBRT trial for early-stage glottic larynx cancer. Baseline SBRT treatment plans were generated per protocol. Daily cone-beam CT (CBCT) or diagnostic CT images were acquired prior to each treatment fraction. Simulation CT images and target volumes were deformably registered to daily volumetric images, the original SBRT plan was copied to the deformed images and contours, delivered dose distributions were re-calculated on the deformed CT images. All of these were performed on a commercial treatment planning system. In-house software was developed to propagate the delivered dose distribution back to reference CT images using the deformation information exported from the treatment planning system. Dosimetric differences were evaluated via dose-volume histograms. We could evaluate dose within 10 minutes in all cases. Prescribed coverage to gross tumor volume (GTV) and clinical target volume (CTV) was uniformly preserved; however, intended prescription dose coverage of planning treatment volume (PTV) was lost in 53% of daily treatments (mean: 93.9%, range: 83.9-97.9%). Maximum bystander point dose limits to arytenoids, parotids, and spinal cord remained respected in all cases, although variances in carotid artery doses were observed in a minority of cases. Although GTV and CTV SBRT dose coverage is preserved with in-room three-dimensional image guidance, PTV coverage can vary significantly from intended plans and dose to critical structures may exceed tolerances. Online adaptive treatment re-planning is potentially necessary and clinically applicable to fully preserve treatment

TU-H-CAMPUS-JeP3-04: Factors Predicting a Need for Treatment Replanning with Proton Radiotherapy for Lung Cancer

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Teng, C; Janssens, G; Ainsley, C; Teo, B; Valdes, G; Burgdorf, B; Berman, A; Levin, W; Xiao, Y; Lin, L; Gabriel, P; Simone, C; Solberg, T [University of Pennsylvania, Philadelphia, PA (United States)

2016-06-15

Purpose: Proton dose distribution is sensitive to tumor regression and tissue and normal anatomy changes. Replanning is sometimes necessary during treatment to ensure continue tumor coverage or avoid overtreatment of organs at risk (OARs). We investigated action thresholds for replanning and identified both dosimetric and non-dosimetric metrics that would predict a need for replan. Methods: All consecutive lung cancer patients (n = 188) who received definitive proton radiotherapy and had more than two evaluation CT scans at the Roberts Proton Therapy Center (Philadelphia, USA) from 2011 to 2015 were included in this study. The cohort included a variety of tumor sizes, locations, histology, beam angles, as well as radiation-induced tumor and lung change. Dosimetric changes during therapy were characterized by changes in the dose volume distribution of PTV, ITV, and OARs (heart, cord, esophagus, brachial plexus and lungs). Tumor and lung change were characterized by changes in sizes, and in the distribution of Hounsfield numbers and water equivalent thickness (WET) along the beam path. We applied machine learning tools to identify both dosimetric and non-dosimetric metrics that predicted a replan. Results: Preliminary data showed that clinical indicators (n = 54) were highly correlated; thus, a simple indicator may be derived to guide the action threshold for replanning. Additionally, tumor regression alone could not predict dosimetric changes in OARs; it required further information about beam angles and tumor locations. Conclusion: Both dosimetric and non-dosimetric factors are predictive of the need for replanning during proton treatment.

Verification system development a dosimetric tridimensional using Solution Fricke gel in the application for verification of radiation therapy in arc modulated volumetric (VMAT) in treatment with target moving for breathing

International Nuclear Information System (INIS)

Sakuraba, Roberto Kenji

2015-01-01

Volumetric Modulated Arc Therapy (VMAT) is one of the methods most commonly used in teletherapy to treat cancer. The various technological advances and the evolution of treatment techniques made the VMAT as one of the state of the art methods for the treatment of some cancers. Part of this improvement is credited to improvements in accuracy and prescription dose absorbed recommended to the patient over the years. This advance allows currently is possible to perform dosimetric calculations by means of the computerized planning system, considering the heterogeneity of patients, such as tissues and organs with different water compositions medium (reference radiation), and individual patient contour the movement of tumors breathing. Such advances require quality control of these tools, in order to ensure that the entire treatment process is satisfactory and accurate. Up to now, the community lacks an experimental system capable of evaluating, considering the uncertainty levels if the computerized planning systems are able to consider the movement of targets in the treatments with VMAT. In this paper, will be presented the results obtained with the phantom Fricke Xylenol Gel, capable of measuring the differences introduced by movement using the Magnetic Resonance Image - MRI and compared qualitatively and quantitatively. The main stages of the phantom development, their experimental results, conclusions and comparisons with other systems are discussed. (author)

Cost-Effectiveness Comparison of Breast Cancer Screening and Vascular Event Primary Prevention with Aspirin in Wales

Science.gov (United States)

Morgan, Gareth

2011-01-01

Aim: For the first time, this article presents a cost-effectiveness comparison of a breast cancer screening programme with a possible health education programme with aspirin for vascular event primary prevention. Background: Breast cancer screening is a well established part of cancer control programmes yet recent evidence on this intervention has…

Dosimetric impact of inter-observer variability for 3D conformal radiotherapy and volumetric modulated arc therapy: the rectal tumor target definition case

International Nuclear Information System (INIS)

Lobefalo, Francesca; Cozzi, Luca; Scorsetti, Marta; Mancosu, Pietro; Bignardi, Mario; Reggiori, Giacomo; Tozzi, Angelo; Tomatis, Stefano; Alongi, Filippo; Fogliata, Antonella; Gaudino, Anna; Navarria, Piera

2013-01-01

To assess the dosimetric effect induced by inter-observer variability in target definition for 3D-conformal RT (3DCRT) and volumetric modulated arc therapy by RapidArc (RA) techniques for rectal cancer treatment. Ten patients with rectal cancer subjected to neo-adjuvant RT were randomly selected from the internal database. Four radiation oncologists independently contoured the clinical target volume (CTV) in blind mode. Planning target volume (PTV) was defined as CTV + 7 mm in the three directions. Afterwards, shared guidelines between radiation oncologists were introduced to give general criteria for the contouring of rectal target and the four radiation oncologists defined new CTV following the guidelines. For each patient, six intersections (I) and unions (U) volumes were calculated coupling the contours of the various oncologists. This was repeated for the contours drawn after the guidelines. Agreement Index (AI = I/U) was calculated pre and post guidelines. Two RT plans (one with 3DCRT technique using 3–4 fields and one with RA using a single modulated arc) were optimized on each radiation oncologist’s PTV. For each plan the PTV volume receiving at least 95% of the prescribed dose (PTV V95%) was calculated for both target and non-target PTVs. The inter-operator AI pre-guidelines was 0.57 and was increased up to 0.69 post-guidelines. The maximum volume difference between the various CTV couples, drawn for each patient, passed from 380 ± 147 cm 3 to 137 ± 83 cm 3 after the introduction of guidelines. The mean percentage for the non-target PTV V95% was 93.7 ± 9.2% before and 96.6 ± 4.9%after the introduction of guidelines for the 3DCRT, for RA the increase was more relevant, passing from 86.5 ± 13.8% (pre) to 94.5 ± 7.5% (post). The OARs were maximally spared with VMAT technique while the variability between pre and post guidelines was not relevant in both techniques. The contouring inter-observer variability has dosimetric effects in the PTV coverage

Are there any dosimetric advantages in using VMAT for treatment of locally advanced non-small cell lung cancer?

International Nuclear Information System (INIS)

Rousseau, D.; Krhili, S.; Yossi, S.; Cellier, P.; Paumier, A.; Autret, D.; Dupas, A.; Edouard, M.; Mahe, M.A.; Giraud, P.; Le Pechoux, C.; Denis, F.

2012-01-01

Purpose. - To analyse the dosimetric differences between the conventional conformal radiation therapy (CR) and the volumetric modulated arc therapy (VMAT) for non-small-cell locally advanced lung cancer (NSCLC). Patients and methods. - Two plans (CR and VMAT) were calculated for ten NSCLC patients. Dose to PTV, organs at risk and external contours (body), conformity index (PTV volume/volume of the 95% reference isodose) and homogeneity index ([maximal dose - minimal dose]/dose prescription) were compared. Results. - Doses delivered to PTV (homogeneity index, maximal, minimal and mean dose) are similar with both techniques but conformity index is improved by 60% with VMAT: from 0.55 ± 0.07 with CR to 0.89 ± 0.07 with VMAT (P = 0.002). Pulmonary protection is improved with VMAT: with CR and VMAT, respectively, the mean lung dose is 14.1 ± 5.2 Gy and 12.2 ± 4.5 Gy, the lung volume which receives at least 30 Gy (V30) is 20 ± 8% and 14 ± 5%, and the V20 is 24 ± 11% and 20 ± 10% (P = 0.002). The mean dose received by the body is also 9% lower (P = 0.004) and V5 is 13% higher (P = 0.004) with VMAT. V10 and V15 were similar with both modalities. From 20 Gy and higher, irradiated body volume is larger with CR than with VMAT. The relative difference increases with the dose: from 10% for 20 Gy (P = 0.014) up to 39% for 62.7 Gy (P = 0.002). Conclusion. - Compared to CR, VMAT greatly improves conformity and reduces mean dose and dose delivered from 20 Gy and higher to the lungs and the body. (authors)

Dosimetric comparison using different multileaf collimeters in intensity-modulated radiotherapy for upper thoracic esophageal cancer

Directory of Open Access Journals (Sweden)

Fu Yuchuan

2010-07-01

Full Text Available Abstract Purpose To study the impacts of multileaf collimators (MLC width [standard MLC width of 10 mm (sMLC and micro-MLC width of 4 mm (mMLC] in the intensity-modulated radiotherapy (IMRT planning for the upper thoracic esophageal cancer (UTEC. Methods and materials 10 patients with UTEC were retrospectively planned with the sMLC and the mMLC. The monitor unites (MUs and dose volume histogram-based parameters [conformity index (CI and homogeneous index (HI] were compared between the IMRT plans with sMLC and with mMLC. Results The IMRT plans with the mMLC were more efficient (average MUs: 703.1 ± 68.3 than plans with the sMLC (average MUs: 833.4 ± 73.8 (p p 5 (3260.3 ± 374.0 vs 3404.5 ± 374.4/gEUD (1815.1 ± 281.7 vs 1849.2 ± 297.6 of the spinal cord, the V10 (33.2 ± 6.5 vs 34.0 ± 6.7, V20 (16.0 ± 4.6 vs 16.6 ± 4.7, MLD (866.2 ± 174.1 vs 887.9 ± 172.1 and gEUD (938.6 ± 175.2 vs 956.8 ± 171.0 of the lungs were observed in the plans with the mMLC, respectively (p Conclusions Comparing to the sMLC, the mMLC not only demonstrated higher efficiencies and more optimal target coverage, but also considerably improved the dose sparing of OARs in the IMRT planning for UTEC.

Thermoluminescence dosimetric characteristics of thulium doped ZnB{sub 2}O{sub 4} phosphor

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Annalakshmi, O. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Jose, M.T., E-mail: mtj@igcar.gov.in [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Madhusoodanan, U. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Subramanian, J. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai (India); Venkatraman, B. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Amarendra, G. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Mandal, A.B. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai (India)

2014-02-15

Polycrystalline powder samples of rare earth doped Zinc borates were synthesized by high temperature solid state diffusion technique. Dosimetric characteristics of the phosphor like thermoluminescence glow curve, TL emission spectra, dose–response, fading studies, reproducibility and reusability studies were carried out on the synthesized phosphors. Among the different rare earth doped phosphors, thulium doped zinc borate was found to have a higher sensitivity. Hence detailed dosimetric characteristics of this phosphor were carried out. It is observed that the dose–response is linear from 10 mGy to 10{sup 3} Gy in this phosphor. EPR measurements were carried out on unirradiated, gamma irradiated and annealed phosphors to identify the defect centers responsible for thermoluminescence. A TL model is proposed based on the EPR studies in these materials. Kinetic parameters were evaluated for the dosimetric peaks using various methods. The experimental results show that this phosphor can have potential applications in radiation dosimetry applications. -- Highlights: • Polycrystalline powder samples of rare earth doped zinc borates were synthesized. • Thulium was observed to be the most efficient dopant in ZnB{sub 2}O{sub 4} lattice. • TL intensity of the dosimetric peak is around 20 times that of TLD-100. • Based on EPR studies a TL mechanism is proposed in zinc borate. • Deconvolution of the glow curve carried out.

Development of optimized dosimetric models for HDR brachytherapy

International Nuclear Information System (INIS)

Thayalan, K.; Jagadeesan, M.

2003-01-01

High dose rate brachytherapy (HDRB) systems are in clinical use for more than four decades particularly in cervical cancer. Optimization is the method to produce dose distribution which assures that doses are not compromised at the treatment sites whilst reducing the risk of overdosing critical organs. Hence HDRB optimization begins with the desired dose distribution and requires the calculations of the relative weighting factors for each dwell position with out changing the source activity. The optimization for Ca. uterine cervix treatment is simply duplication of the dose distribution used for Low dose rate (LDR) applications. In the present work, two optimized dosimetric models were proposed and studied thoroughly, to suit the local clinical conditions. These models are named as HDR-C and HDR-D, where C and D represent configuration and distance respectively. These models duplicate exactly the LDR pear shaped dose distribution, which is a golden standard. The validity of these models is tested in different clinical situations and in actual patients (n=92). These models: HDR-C and HDR-D reduce bladder dose by 11.11% and 10% and rectal dose by 8% and 7% respectively. The treatment time is also reduced by 12-14%. In a busy hospital setup, these models find a place to cater large number of patients, while addressing individual patients geometry. (author)

The Impact of Adjustment for Socioeconomic Status on Comparisons of Cancer Incidence between Two European Countries

International Nuclear Information System (INIS)

Donnelly, D. W.; Gavin, A.; Hegarty, A.

2013-01-01

Cancer incidence rates vary considerably between countries and by socioeconomic status (SES). We investigate the impact of SES upon the relative cancer risk in two neighbouring countries. Methods. Data on 229,824 cases for 16 cancers diagnosed in 1995-2007 were extracted from the cancer registries in Northern Ireland (NI) and Republic of Ireland (RoI). Cancers in the two countries were compared using incidence rate ratios (IRRs) adjusted for age and age plus area-based SES. Results. Adjusting for SES in addition to age had a considerable impact on NI/RoI comparisons for cancers strongly related to SES. Before SES adjustment, lung cancer incidence rates were 11% higher for males and 7% higher for females in NI, while after adjustment, the IRR was not statistically significant. Cervical cancer rates were lower in NI than in RoI after adjustment for age (IRR: 0.90 (0.84-0.97)), with this difference increasing after adjustment for SES (IRR: 0.85 (0.79-0.92)). For cancers with a weak or nonexistent relationship to SES, adjustment for SES made little difference to the IRR. Conclusion. Socioeconomic factors explain some international variations but also obscure other crucial differences; thus, adjustment for these factors should not become part of international comparisons.

Clinical and dosimetric evaluation of RapidArc versus standard sliding window IMRT in the treatment of head and neck cancer

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Smet, Stephanie; Lambrecht, Maarten; Vanstraelen, Bianca; Nuyts, Sandra [University Hospitals Leuven, Department of Radiation Oncology, Leuven (Belgium)

2014-08-29

Several planning studies have already proven the substantial dosimetric advantages of RapidArc (RA) over standard intensity-modulated radiotherapy. We retrospectively compared RapidArc and standard sliding window IMRT (swIMRT) in locally advanced head and neck cancer, looking both at dosimetrics as well as toxicity and outcome. CT datasets of 78 patients treated with swIMRT and 79 patients treated with RA were included. To compare the resulting dose distributions, the dose-volume parameters were evaluated for the planning target volumes (PTVs), clinical target volumes (CTVs), and organs at risk (OARs), and the number of MU were calculated. Acute toxicity was assessed by the Common Toxicity Criteria version 3.0. PTV coverage with the 95 % isodose was slightly better for RA. Dose distribution has proven to be significantly more homogenous with RA and led to a reduction of 62 % in MU with better OAR sparing. As for toxicity, more grade 3 mucositis and dysphagia was observed for swIMRT, though we observed more grade 3 dermatitis for RA. In our retrospective analysis, RA had better target coverage and better sparing of the OAR. Overall, the grade of acute toxicity was lower for RA than for swIMRT for the same types of tumor locations, except for the grade of dermatitis. (orig.) [German] Mehrere Studien haben die dosimetrische Ueberlegenheit der RapidArc (RA) gegenueber der intensitaetsmodulierten Standard-Radiotherapie (IMRT) bereits gezeigt. In unserer Studie verglichen wir retrospektiv die RapidArc und die dynamische (''standard sliding window'') IMRT (swIMRT) bei lokal fortgeschrittenen Kopf-Hals-Karzinomen sowohl hinsichtlich dosimetrischer Daten als auchEffektivitaet und Toxizitaet. Die CT-Datenanalysen von 78 Patienten, die mit swIMRT behandelt wurden, und von 79 Patienten, welche RA erhalten hatten, wurden in die Studie aufgenommen. Um die darauf resultierenden applizierten Dosen vergleichen zu koennen, wurden die Dosis-Volumen-Parameter fuer

Intensity-Modulated Proton Therapy Further Reduces Normal Tissue Exposure During Definitive Therapy for Locally Advanced Distal Esophageal Tumors: A Dosimetric Study

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Welsh, James, E-mail: jwelsh@mdanderson.org [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Gomez, Daniel; Palmer, Matthew B.; Riley, Beverly A.; Mayankkumar, Amin V.; Komaki, Ritsuko [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Dong, Lei; Zhu, X. Ronald [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Likhacheva, Anna; Liao, Zhongxing [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Hofstetter, Wayne L. [Department of Thoracic and Cardiovascular Surgery, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Ajani, Jaffer A. [Department of Gastrointestinal Medical Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Cox, James D. [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)

2011-12-01

Purpose: We have previously found that {<=} 75% of treatment failures after chemoradiotherapy for unresectable esophageal cancer appear within the gross tumor volume and that intensity-modulated (photon) radiotherapy (IMRT) might allow dose escalation to the tumor without increasing normal tissue toxicity. Proton therapy might allow additional dose escalation, with even lower normal tissue toxicity. In the present study, we compared the dosimetric parameters for photon IMRT with that for intensity-modulated proton therapy (IMPT) for unresectable, locally advanced, distal esophageal cancer. Patients and Methods: Four plans were created for each of 10 patients. IMPT was delivered using anteroposterior (AP)/posteroanterior beams, left posterior oblique/right posterior oblique (LPO/RPO) beams, or AP/LPO/RPO beams. IMRT was delivered with a concomitant boost to the gross tumor volume. The dose was 65.8 Gy to the gross tumor volume and 50.4 Gy to the planning target volume in 28 fractions. Results: Relative to IMRT, the IMPT (AP/posteroanterior) plan led to considerable reductions in the mean lung dose (3.18 vs. 8.27 Gy, p < .0001) and the percentage of lung volume receiving 5, 10, and 20 Gy (p {<=} .0006) but did not reduce the cardiac dose. The IMPT LPO/RPO plan also reduced the mean lung dose (4.9 Gy vs. 8.2 Gy, p < .001), the heart dose (mean cardiac dose and percentage of the cardiac volume receiving 10, 20, and 30 Gy, p {<=} .02), and the liver dose (mean hepatic dose 5 Gy vs. 14.9 Gy, p < .0001). The IMPT AP/LPO/RPO plan led to considerable reductions in the dose to the lung (p {<=} .005), heart (p {<=} .003), and liver (p {<=} .04). Conclusions: Compared with IMRT, IMPT for distal esophageal cancer lowered the dose to the heart, lung, and liver. The AP/LPO/RPO beam arrangement was optimal for sparing all three organs. The dosimetric benefits of protons will need to be tailored to each patient according to their specific cardiac and pulmonary risks. IMPT for

Dosimetric behavior of thermoluminescent dosimeters at low doses in diagnostic radiology; Comportamiento dosimetrico de dosimetros termoluminiscentes a bajas dosis en radiodiagnostico

Energy Technology Data Exchange (ETDEWEB)

Del Sol F, S.; Garcia S, R.; Guzman M, J.; Sanchez G, D.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Ramirez R, G. [Hospital Juarez de Mexico, Av. IPN 5160, Col. Magdalena de las Salinas, 07760 Mexico D. F. (Mexico); Gaona, E., E-mail: susi2489@hotmail.com [Universidad Autonoma Metropolitana, Unidad Xochimilco, Calz. del Hueso 1100, Col. Villa Quietud, 04960 Mexico D. F. (Mexico)

2015-10-15

Thermoluminescent (Tl) characteristics of TLD-100, LiF:Mg,Cu,P, and CaSO{sub 4}: Dy the under homogeneous field of X-ray beams of diagnostic irradiation and its verification using thermoluminescent dosimetry is presented. The irradiations were performed utilizing an X-ray beam generated by a Radiology Mexican Company: MRH-II E GMX 325-AF SBV-1 model, with Rotating Anode X-Ray Tube installed in the Hospital Juarez Norte de Mexico in Mexico City. Different thermoluminescent characteristics of dosimetric material were studied, such as, batch homogeneity, Tl glow curve, Tl response as a function of X-ray dose, reproducibility and fading. Materials were calibrated in terms of absorbed dose to the standard calibration distance and positioned in a generic Phantom was used. Dose verification and comparison with the measurements made with that obtained by TLD-100 were analyzed. Preliminary results indicate the dosimetric peak appears at 243, 236 and 277 ± 5 degrees C respectively, these peaks are in agreement with that reported in the literature. Tl glow curve as a function of X-ray dose showed a linearity in the range from 1.76 mGy up to 14.70 mGy for all materials. Fading for a period of one month at room temperature showed low fading LiF:Mg,Cu,P, medium and high for TLD-100 and CaSO{sub 4}: Dy. The results suggest that the three materials are suitable for measurements at low doses in radiodiagnostic, however, for its dosimetric characteristics are most effective for individual applications: personal dosimetry and monitors limb (LiF:Mg,Cu,P), clinical dosimetry and environmental (TLD-100 and CaSO{sub 4}: Dy). (Author)

Dosimetric study in iodine-125 seeds for brachytherapy application

International Nuclear Information System (INIS)

Zeituni, Carlos Alberto

2008-01-01

The demand for iodine-125 seeds for use in brachytherapy treatments has experienced an increase along recent years in Brazil and all over the world. All iodine-125 seed must have its operational parameters measured and/or calculated every time changes in the production process are carried out. A complete dosimetric measurement is very expensive, and it is recommended that this procedure must be repeated at least once a year. Thus, this work developed a methodology for the entire dosimetric process. This methodology is based on the scarce information available in the literature, once almost all the methodology used in large industrial laboratories is commercial secret. The proposed methodology was tested using seeds of Amersham-Oncura-Ge Healthcare, which is the largest seed manufactory in the world. In this new methodology, an automatic reader was employed in order to reduce the time required in the selection process of the TLD-100 dosimeters used and a postprocessing of the obtained spectra was carried out. A total of 142 dosimeters were used and only 29 have been selected using the new methodology. Measurements were performed using slabs of Solid Water RW1 to simulate measuring in the 'water', using three different experimental apparatus and each measurement was repeated at least three times. The TLD-100 calibration was performed using a Dermopan II - Siemens. The measured values showed a good agreement with the ones available in the literature. Finally, these measured values were compared with calculated ones obtained by a semiempirical simulation program, showing a good agreement and, therefore, demonstrating the validity of the proposed methodology regarding dosimetric calculations. (author)

Dosimetric considerations and early clinical experience of accelerated partial breast irradiation using multi-lumen applicators in the setting of breast augmentation

Science.gov (United States)

Akhtari, Mani; Pino, Ramiro; Scarboro, Sarah B.; Bass, Barbara L.; Miltenburg, Darlene M.; Butler, E. Brian

2015-01-01

Purpose Accelerated partial breast irradiation (APBI) is an accepted treatment option in breast-conserving therapy for early stage breast cancer. However, data regarding outcomes of patients treated with multi-lumen catheter systems who have existing breast implants is limited. The purpose of this study was to report treatment parameters, outcomes, and possible dosimetric correlation with cosmetic outcome for this population of patients at our institution. Material and methods We report the treatment and outcome of seven consecutive patients with existing breast implants and early stage breast cancer who were treated between 2009 and 2013 using APBI following lumpectomy. All patients were treated twice per day for five days to a total dose of 34 Gy using a high-dose-rate 192Ir source. Cosmetic outcomes were evaluated using the Harvard breast cosmesis scale, and late toxicities were reported using the Radiation Therapy Oncology Group (RTOG) late radiation morbidity schema. Results After a mean follow-up of 32 months, all patients have remained cancer free. Six out of seven patients had an excellent or good cosmetic outcome. There were no grade 3 or 4 late toxicities. The average total breast implant volume was 279.3 cc, received an average mean dose of 12.1 Gy, and a maximum dose of 234.1 Gy. The average percentage of breast implant volume receiving 50%, 75%, 100%, 150%, and 200% of the prescribed dose was 15.6%, 7.03%, 4.6%, 1.58%, and 0.46%, respectively. Absolute volume of breast implants receiving more than 50% of prescribed dose correlated with worse cosmetic outcomes. Conclusions Accelerated partial breast irradiation using a multi-lumen applicator in patients with existing breast implants can safely be performed with promising early clinical results. The presence of the implant did not compromise the ability to achieve dosimetric criteria; however, dose to the implant and the irradiated implant volume may be related with worse cosmetic outcomes. PMID:26816499

A feasibility dosimetric study on prostate cancer. Are we ready for a multicenter clinical trial on SBRT?

Energy Technology Data Exchange (ETDEWEB)

Marino, Carmelo; Bonanno, Elisa [Humanitas C.C.O., Catania (Italy); Villaggi, Elena [AUSL, Piacenza (Italy); Maggi, Giulia; Mancosu, Pietro [IRCCS Humanitas Clinical Research Center, Milan (Italy); Esposito, Marco [Azienda Sanitaria Firenze (Italy); Strigari, Lidia [Regina Elena National Cancer Institute, Rome (Italy). Lab. of Medical Physics and Expert Systems; Borzi, Giusi R. [REM Radioterapia, Catania (Italy); Carbonini, Claudia [A.O. Ospedale Niguarda Ca' Granda, Milan (Italy); Consorti, Rita [ACO S. Filippo Neri, Rome (Italy); Fedele, David [Casa di Cura Privata San Rossore s.r.l., Pisa (Italy); Fiandra, Christian [Torino Univ. (Italy). Radiation Oncology Unit; Ielo, Isidora [A.O.U. Policlinico G. Martino, Messina (Italy); Malatesta, Tiziana [' ' S. Giovanni Calibita' ' Fatebenefratelli, Rome (Italy); Malisan, Maria Rosa [Azienda Ospedaliero-Universitaria di Udine (Italy); Martinotti, Anna [Centro Diagnostico Italiano, Milan (Italy); Moretti, Renzo [Az. Ospedaliera Spedali Civili di Brescia (Italy); Nardiello, Barbara [UPMC San Pietro FBF, Rome (Italy); Oliviero, Caterina; Clemente, Stefania [IRCCS CROB Rieonero in Vulture, Potenza (Italy)

2015-07-15

The Italian Association of Medical Physics (AIFM) started a working group dedicated to stereotactic body radiotherapy (SBRT) treatment. In this work, we performed a multicenter planning study on patients who were candidates for SBRT in the treatment of prostate cancer with the aim of evaluating the dosimetric consistency among the different hospitals. Fourteen centers were provided the contours of 5 patients. Plans were performed following the dose prescription and constraints for organs at risk (OARs) of a reference paper. The dose prescription was 35 Gy in five fractions for the planning target volume (PTV). Different techniques were used (3D-CRT, fixed-Field IMRT, VMAT, CyberKnife). Plans were compared in terms of dose-volume histogram (DVH) parameters. Furthermore, the median DVH was calculated and one patient was re-planned. A total of 70 plans were compared. The maximum dose to the body was 107.9 ± 4.5 % (range 101.5-116.3 %). Dose at 98 % (D{sub 98} {sub %}) and mean dose to the clinical target volume (CTV) were 102.0 ± 0.9 % (global range 101.1-102.9 %) and 105.1 ± 0.6 % (range 98.6-124.6 %). Similar trends were found for D{sub 95} {sub %} and mean dose to the PTV. Important differences were found in terms of the homogeneity index. Doses to OARs were heterogeneous. The subgroups with the same treatment planning system showed differences comparable to the differences of the whole group. In the re-optimized plans, DVH differences among institutes were reduced and OAR sparing improved. Important dosimetric differences with possible clinical implications, in particular related to OARs, were found. Replanning allowed a reduction in the OAR dose and decreased standard deviations. Multicenter clinical trials on SBRT should require a preplanning study to standardize the optimization procedure. (orig.) [German] Der italienische Verband der Medizinphysiker (AIFM) hat eine Arbeitsgruppe gegruendet, die sich mit der Koerperstammstereotaxie (SBRT) befasst. Im Rahmen

Effect of photon energy spectrum on dosimetric parameters of brachytherapy sources.

Science.gov (United States)

Ghorbani, Mahdi; Mehrpouyan, Mohammad; Davenport, David; Ahmadi Moghaddas, Toktam

2016-06-01

The aim of this study is to quantify the influence of the photon energy spectrum of brachytherapy sources on task group No. 43 (TG-43) dosimetric parameters. Different photon spectra are used for a specific radionuclide in Monte Carlo simulations of brachytherapy sources. MCNPX code was used to simulate 125I, 103Pd, 169Yb, and 192Ir brachytherapy sources. Air kerma strength per activity, dose rate constant, radial dose function, and two dimensional (2D) anisotropy functions were calculated and isodose curves were plotted for three different photon energy spectra. The references for photon energy spectra were: published papers, Lawrence Berkeley National Laboratory (LBNL), and National Nuclear Data Center (NNDC). The data calculated by these photon energy spectra were compared. Dose rate constant values showed a maximum difference of 24.07% for 103Pd source with different photon energy spectra. Radial dose function values based on different spectra were relatively the same. 2D anisotropy function values showed minor differences in most of distances and angles. There was not any detectable difference between the isodose contours. Dosimetric parameters obtained with different photon spectra were relatively the same, however it is suggested that more accurate and updated photon energy spectra be used in Monte Carlo simulations. This would allow for calculation of reliable dosimetric data for source modeling and calculation in brachytherapy treatment planning systems.

The big five and identification-contrast processes in social comparison in adjustment to cancer treatment

NARCIS (Netherlands)

van der Zee, KI; Buunk, BP; Sanderman, R; Botke, G; van den Bergh, F

1999-01-01

The present study examined the relationship between social comparison processes and the Big Five personality factors. In a sample of 112 patients with various forms of cancer it was found that Neuroticism was associated with a tendency to focus on the negative interpretation of social comparison

Dosimetric investigations in mammography

International Nuclear Information System (INIS)

Metges, P.J.; Lorrain, S.

1981-01-01

The development film-screen detectors in radiological equipment has led us to study how to improve standard mammographic pictures (focus 0.3 x 0.3 mm, focus-film distance: 65) of thick and dense breasts by the use of an anti-scatter grid and by magnification. A dosimetric study was necessary to assess the doses delivered during mammographic examinations carried out according to various procedures. The results led to modify breast examination procedures and use an anti-scatter grid for breasts thicker than 4 cm or known as dense. The dose increase due to a better quality image is the lowest provided depth penetration is increased by 2 kV as compared to a standard picture. Absorbed doses on the X-ray axis, at 3 cm depth, are below 0.1 rad [fr

Dosimetric verification of the intensity-modulated radiation therapy

International Nuclear Information System (INIS)

Zou Huawei; Jia Mingxuan; Wu Rong; Xiao Fuda; Dong Xiaoqi

2004-01-01

Objective: To discuss the methods of the dosimetric verification in the intensity-modulated radiation therapy (IMRT) and insure correct execution of the IMRT planning in the clinical practice. Methods: The CMSFOCUS9200 inverse planning system was used to provide optimized 5-field IMRT treatment plans for the patients. A phantom was made from true water-equivalent material. The doses of the interesting points and isodose distributions of the interesting planes in the phantom were calculated using patients' treatment plan. The phantom was placed on the couch of the accelerator and was irradiated using the phantom's treatment planning data. The doses of interesting points were measured using a 0.23 cc chamber and the isodose distributions of interesting planes were measured using RIT 113 film dosimetry system in the phantom. The results were compared with those from calculation in planning system for verification. Results: The doses and isodose distributions measured by the chamber and the film were consistent with those predicted by the planning. The error between the measured dose and calculated dose in the interesting points was less than 3%. Conclusion: The dosimetric verification of IMRT is a reliable measure in the course of its implementation. (authors)

Differentiated thyroid cancer treatment with therapeutic doses of 131I calculated by dosimetry: our experience

International Nuclear Information System (INIS)

Fadel, Ana M.; Chebel, G.M.; Valdivieso, C.M.; Degrossi, Osvaldo J.; Cabrejas, R.; Cabrejas, M.L.

2006-01-01

The optimum dose for the differentiated thyroid cancer treatment is a motive of controversy. There exist two ways of deciding the dose to administer: the empirical method (fixed doses) and dosimetric calculation method. The use of fixed doses has demonstrated safety and effectiveness. Nevertheless there are cases in which the use of several small doses not resolves the metastases illness of the patients. Using the Benua-Leeper method for dosimetric calculation we have evaluated the maximum dose treatment that could be administered to 20 patients who showed persistent disease after several treatments with 131 I. (author) [es

Rapid Arc, helical tomotherapy, sliding window intensity modulated radiotherapy and three dimensional conformal radiation for localized prostate cancer: A dosimetric comparison

Directory of Open Access Journals (Sweden)

Rajesh A Kinhikar

2014-01-01

Full Text Available Objective: The objective of this study was to investigate the potential role of RapidArc (RA compared with helical tomotherapy (HT, sliding window intensity modulated radiotherapy (SW IMRT and three-dimensional conformal radiation therapy (3D CRT for localized prostate cancer. Materials and Methods: Prescription doses ranged from 60 Gy to planning target volume (PTV and 66.25 Gy for clinical target volume prostate (CTV-P over 25-30 fractions. PTV and CTV-P coverage were evaluated by conformity index (CI and homogeneity index (HI. Organ sparing comparison was done with mean doses to rectum and bladder. Results: CI 95 were 1.0 ± 0.01 (RA, 0.99 ± 0.01 (HT, 0.97 ± 0.02 (IMRT, 0.98 ± 0.02 (3D CRT for PTV and 1.0 ± 0.00 (RA, HT, SW IMRT and 3D CRT for CTV-P. HI was 0.11 ± 0.03 (RA, 0.16 ± 0.08 (HT, 0.12 ± 0.03 (IMRT, 0.06 ± 0.01 (3D CRT for PTV and 0.03 ± 0.00 (RA, 0.05 ± 0.01 (HT, 0.03 ± 0.01 (SW IMRT and 3D CRT for CTV-P. Mean dose to bladder were 23.68 ± 13.23 Gy (RA, 24.55 ± 12.51 Gy (HT, 19.82 ± 11.61 Gy (IMRT and 23.56 ± 12.81 Gy (3D CRT, whereas mean dose to rectum was 36.85 ± 12.92 Gy (RA, 33.18 ± 11.12 Gy (HT, IMRT and 38.67 ± 12.84 Gy (3D CRT. Conclusion: All studied intensity-modulated techniques yield treatment plans of significantly improved quality when compared with 3D CRT, with HT providing best organs at risk sparing and RA being the most efficient treatment option, reducing treatment time to 1.45-3.7 min and monitor unit to <400 for a 2 Gy fraction.

Rectal dose assessment in patients submitted to high-dose-rate brachytherapy for uterine cervix cancer

International Nuclear Information System (INIS)

Oliveira, Jetro Pereira de; Batista, Delano Valdivino Santos; Bardella, Lucia Helena; Carvalho, Arnaldo Rangel

2009-01-01

Objective: The present study was aimed at developing a thermoluminescent dosimetric system capable of assessing the doses delivered to the rectum of patients submitted to high-dose-rate brachytherapy for uterine cervix cancer. Materials and methods: LiF:Mg,Ti,Na powder was the thermoluminescent material utilized for evaluating the rectal dose. The powder was divided into small portions (34 mg) which were accommodated in a capillary tube. This tube was placed into a rectal probe that was introduced into the patient's rectum. Results: The doses delivered to the rectum of six patients submitted to high-dose-rate brachytherapy for uterine cervix cancer evaluated by means of thermoluminescent dosimeters presented a good agreement with the planned values based on two orthogonal (anteroposterior and lateral) radiographic images of the patients. Conclusion: The thermoluminescent dosimetric system developed in the present study is simple and easy to be utilized as compared to other rectal dosimetry methods. The system has shown to be effective in the evaluation of rectal doses in patients submitted to high-dose-rate brachytherapy for uterine cervix cancer. (author)

Dose reader of dosimetric foil; Czytnik dawki folii dozymetrycznej

Energy Technology Data Exchange (ETDEWEB)

Machaj, B.; Strzalkowski, J.; Smolko, K.

1997-12-31

Read out the absorbance of a dosimetric foil is accomplished by two beam spectrophotometer. Such a solution makes possible the compensation of light source instabilities and ensures higher stability of the dose reader. The error of absorbance measurement caused by the instabilities does not exceed 0.0004 A. (author). 3 refs, 3 figs.

SU-E-T-10: A Dosimetric Comparison of Copper to Lead-Alloy Apertures for Electron Beam Therapy

Energy Technology Data Exchange (ETDEWEB)

Rusk, B; Hogstrom, K; Gibbons, J; Carver, R [Mary Bird Perkins Cancer Center, Baton Rouge, LA (United States)

2014-06-01

Purpose: To evaluate dosimetric differences of copper compared to conventional lead-alloy apertures for electron beam therapy. Methods: Copper apertures were manufactured by .decimal, Inc. and matching lead-alloy, Cerrobend, apertures were constructed for 32 square field sizes (2×2 – 20×20 cm{sup 2}) for five applicator sizes (6×6–25×25 cm{sup 2}). Percent depth-dose and off-axis-dose profiles were measured using an electron diode in water with copper and Cerrobend apertures for a subset of aperture sizes (6×6, 10×10, 25×25 cm{sup 2}) and energies (6, 12, 20 MeV). Dose outputs were measured for all field size-aperture combinations and available energies (6–20 MeV). Measurements were taken at 100 and 110 cm SSDs. Using this data, 2D planar absolute dose distributions were constructed and compared. Passing criteria were ±2% of maximum dose or 1-mm distance-to-agreement for 99% of points. Results: A gamma analysis of the beam dosimetry showed 93 of 96 aperture size, applicator, energy, and SSD combinations passed the 2%/1mm criteria. Failures were found for small field size-large applicator combinations at 20 MeV and 100-cm SSD. Copper apertures showed a decrease in bremsstrahlung production due to copper's lower atomic number compared to Cerrobend (greatest difference was 2.5% at 20 MeV). This effect was most prominent at the highest energies with large amounts of shielding material present (small field size-large applicator). Also, an increase in electrons scattered from the collimator edge of copper compared to Cerrobend resulted in an increased dose at the field edge for copper at shallow depths (greatest increase was 1% at 20 MeV). Conclusion: Apertures for field sizes ≥6×6 cm{sup 2} at any energy, or for small fields (≤4×4 cm{sup 2}) at energies <20 MeV, showed dosimetric differences less than 2%/1mm for more than 99% of points. All field size-applicator size-energy combinations passed 3%/1mm criteria for 100% of points. Work partially

Depression, anxiety, and somatic symptoms in older cancer patients: a comparison across age groups.

Science.gov (United States)

Cohen, Miri

2014-02-01

Previous studies have reported that older cancer patients experience lower psychological distress than younger patients, but most prior studies do not differentiate between age groups within the 'older' category. The aim of this study was to assess the intensity of the symptoms of depression, anxiety, and somatic symptoms among different age groups of older cancer patients. Participants were composed of 321 cancer patients 60 years and older, who were divided into three age groups: 60-69, 70-79, and 80+ years. The participants answered the Brief Symptom Inventory-18, which included subscales for depression, anxiety, and somatic symptoms and the cancer-related problem list, in addition to providing personal and cancer-related details. Depressive, anxiety, and somatic symptoms and cancer-related problems were lowest in the 70-79 years age group and highest in the 80+ years age group. Comparisons between pairs of groups showed significant differences between each of the groups in Brief Symptom Inventory total scores and between the 80+ years age group and the other two groups in regard to depressive symptoms and cancer-related problems. Differences, related to anxiety and somatic symptoms, were significant for the 70-79 year olds, in comparison with the youngest and oldest groups. Intensity of symptoms was explained by older age, higher number of cancer-related problems, female gender, and lower income. Nonlinear relations exist between age and psychological symptoms, which is in line with the postponement of age-related health and functional decline in the modern era. These results suggest that the study of psychological reactions to cancer should examine differences between age groups among older cancer patients. Copyright © 2013 John Wiley & Sons, Ltd.

The Impact of Adjustment for Socioeconomic Status on Comparisons of Cancer Incidence between Two European Countries

Directory of Open Access Journals (Sweden)

David W. Donnelly

2013-01-01

Full Text Available Background. Cancer incidence rates vary considerably between countries and by socioeconomic status (SES. We investigate the impact of SES upon the relative cancer risk in two neighbouring countries. Methods. Data on 229,824 cases for 16 cancers diagnosed in 1995–2007 were extracted from the cancer registries in Northern Ireland (NI and Republic of Ireland (RoI. Cancers in the two countries were compared using incidence rate ratios (IRRs adjusted for age and age plus area-based SES. Results. Adjusting for SES in addition to age had a considerable impact on NI/RoI comparisons for cancers strongly related to SES. Before SES adjustment, lung cancer incidence rates were 11% higher for males and 7% higher for females in NI, while after adjustment, the IRR was not statistically significant. Cervical cancer rates were lower in NI than in RoI after adjustment for age (IRR: 0.90 (0.84–0.97, with this difference increasing after adjustment for SES (IRR: 0.85 (0.79–0.92. For cancers with a weak or nonexistent relationship to SES, adjustment for SES made little difference to the IRR. Conclusion. Socioeconomic factors explain some international variations but also obscure other crucial differences; thus, adjustment for these factors should not become part of international comparisons.

Variations in the Contouring of Organs at Risk: Test Case From a Patient With Oropharyngeal Cancer

Energy Technology Data Exchange (ETDEWEB)

Nelms, Benjamin E., E-mail: alpha@canislupusllc.com [Canis Lupus LLC, Merrimac, WI (United States); Tome, Wolfgang A. [Department of Human Oncology, University of Wisconsin, Madison, WI (United States); Robinson, Greg [Radiation Oncology Resources, Goshen, IN (United States); Wheeler, James [Department of Radiation Oncology, Goshen Health System Goshen, IN (United States)

2012-01-01

Purpose: Anatomy contouring is critical in radiation therapy. Inaccuracy and variation in defining critical volumes will affect everything downstream: treatment planning, dose-volume histogram analysis, and contour-based visual guidance used in image-guided radiation therapy. This study quantified: (1) variation in the contouring of organs at risk (OAR) in a clinical test case and (2) corresponding effects on dosimetric metrics of highly conformal plans. Methods and Materials: A common CT data set with predefined targets from a patient with oropharyngeal cancer was provided to a population of clinics, which were asked to (1) contour OARs and (2) design an intensity-modulated radiation therapy plan. Thirty-two acceptable plans were submitted as DICOM RT data sets, each generated by a different clinical team. Using those data sets, we quantified: (1) the OAR contouring variation and (2) the impact this variation has on dosimetric metrics. New technologies were employed, including a software tool to quantify three-dimensional structure comparisons. Results: There was significant interclinician variation in OAR contouring. The degree of variation is organ-dependent. We found substantial dose differences resulting strictly from contouring variation (differences ranging from -289% to 56% for mean OAR dose; -22% to 35% for maximum dose). However, there appears to be a threshold in the OAR comparison metric beyond which the dose differences stabilize. Conclusions: The effects of interclinician variation in contouring organs-at-risk in the head and neck can be large and are organ-specific. Physicians need to be aware of the effect that variation in OAR contouring can play on the final treatment plan and not restrict their focus only to the target volumes.

Pulse dose-rate brachytherapy and treatment of uterine cervix cancer: impact of a 3D or a 2D dosimetric support

International Nuclear Information System (INIS)

Tournat, H.; Chilles, A.; Charra-Brunaud, C.; Peiffert, D.; Ahmad, F.; Metayer, Y.

2007-01-01

Purpose To evaluate two dosimetric supports used in pulse dose rate brachytherapy (P.D.R.): coverage of target volumes, dose to organs at risk, residual tumor after surgery, survival. Patients and methods Twenty patients treated for uterine cervix tumor first by brachytherapy P.D.R. had a dosimetric CT-scan after implantation. For 9 patients, the treatment was planned from standard radiographies and then reported on CT-scan images. For 11 patients, it was directly planned from CT-scan. Six weeks after, 18 patients underwent surgery. Results With a median follow-up of 22 months, 2 year actuarial survival was 89%. Six patients developed grade II urinary or gynecological complications (LENT SOMA scale). No residual tumor was found for 12 patients (7 with a 3D treatment and 5 a 2 D treatment). Ninety-five percent of C.T.V.H.R. received 53 Gy (2D treatment) or 63 Gy (3D treatment). Two cm 3 of bladder wall received 63 Gy (2D) or 74 Gy (3D) although 2 cm 3 of rectal wall received 37 Gy (2D) and 35 Gy (3D). Conclusion Using CT-scan made us improve the coverage of the uterine cervix but increase the dose received by the bladder, without increasing the rate of histological remission after surgery. We should be prudent before changing our practice. (authors)

Targeting cancer patients' quality of life through social comparison : A randomised trial

NARCIS (Netherlands)

Brakel, Thecla M.; Dijkstra, Arie; Buunk, Abraham P.

2014-01-01

Objective: Former cancer patients' quality of life can be improved by offering social comparison information. Whether patients, however, benefit from the information may depend on how negative they perceive their present and their future. Design: We conducted a randomised experimental field study

Biologic data, models, and dosimetric methods for internal emitters

International Nuclear Information System (INIS)

Weber, D.A.

1990-01-01

The absorbed radiation dose from internal emitters has been and will remain a pivotal factor in assessing risk and therapeutic utility in selecting radiopharmaceuticals for diagnosis and treatment. Although direct measurements of absorbed dose and dose distributions in vivo have been and will continue to be made in limited situations, the measurement of the biodistribution and clearance of radiopharmaceuticals in human subjects and the use of this data is likely to remain the primary means to approach the calculation and estimation of absorbed dose from internal emitters over the next decade. Since several approximations are used in these schema to calculate dose, attention must be given to inspecting and improving the application of this dosimetric method as better techniques are developed to assay body activity and as more experience is gained in applying these schema to calculating absorbed dose. Discussion of the need for considering small scale dosimetry to calculate absorbed dose at the cellular level will be presented in this paper. Other topics include dose estimates for internal emitters, biologic data mathematical models and dosimetric methods employed. 44 refs

Dosimetric and motion analysis of margin-intensive therapy by stereotactic ablative radiotherapy for resectable pancreatic cancer

Directory of Open Access Journals (Sweden)

Heinzerling John H

2011-10-01

Full Text Available Abstract Background The retroperitoneal margin is a common site of positive surgical margins in patients with resectable pancreatic cancer. Preoperative margin-intensive therapy (MIT involves delivery of a single high dose of ablative radiotherapy (30 Gy focused on this surgically inaccessible margin, utilizing stereotactic techniques in an effort to reduce local failure following surgery. In this study, we investigated the motion of regional organs at risk (OAR utilizing 4DCT, evaluated the dosimetric effects of abdominal compression (AC to reduce regional motion, and compared various planning techniques to optimize MIT. Methods 10 patients were evaluated with 4DCT scans. All 10 patients had scans using AC and seven of the 10 patients had scans both with and without AC. The peak respiratory abdominal organ and major vessel centroid excursion was measured. A "sub-GTV" region was defined by a radiation oncologist and surgical oncologist encompassing the retroperitoneal margin typically lateral and posterior to the superior mesenteric artery (SMA, and a 3-5 mm margin was added to constitute the PTV. Identical 3D non-coplanar SABR (3DSABR plans were designed for the average compression and non-compression scans. Compression scans were planned with 3DSABR, coplanar IMRT (IMRT, and Cyberknife (CK planning techniques. Dose volume analysis was undertaken for various endpoints, comparing OAR doses with and without AC and for different planning methods. Results The mean PTV size was 20.2 cm3. Regional vessel motion of the SMA, celiac trunk, and renal vessels was small ( 5 mm, so AC has been used in all patients enrolled thus far. AC did not significantly increase OAR dose including the stomach and traverse colon. There were several statistically significant differences in the doses to OARs as a function of the type of planning modality used. Conclusions AC does not significantly reduce the limited motion of structures in close proximity to the MIT target

TU-AB-BRA-11: Indications for Online Adaptive Radiotherapy Based On Dosimetric Consequences of Interfractional Pancreas-To-Duodenum Motion in MRI-Guided Pancreatic Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Mittauer, K; Rosenberg, S; Geurts, M; Bassetti, M; Wojcieszynski, A; Harari, P; Labby, Z; Hill, P; Paliwal, B; Bayouth, J [University of Wisconsin, School of Medicine and Public Health, Madison, WI (United States); Chen, I; Henke, L; Kashani, R; Parikh, P [Washington University School of Medicine, St. Louis, MO (United States); Olsen, J [University of Colorado- Denver, Aurora, CO (United States)

2016-06-15

Purpose: Dose limiting structures, such as the duodenum, render the treatment of pancreatic cancer challenging. In this multi-institutional study, we assess dosimetric differences caused by interfraction pancreas-to-duodenum motion using MR-IGRT to determine the potential impact of adaptive replanning. Methods: Ten patients from two institutions undergoing MRI-guided radiotherapy with conventional fractionation (n=5) or SBRT (n=5) for pancreatic cancer were included. Initial plans were limited by duodenal dose constraints of 50 Gy (0.5 cc)/31 Gy (0.1 cc) for conventional/SBRT with prescriptions of 30 Gy/5 fractions (SBRT) and 40–50 Gy/25 fractions (conventional). Daily volumetric MR images were acquired under treatment conditions on a clinical MR-IGRT system. The correlation was assessed between interfractional GTV-to-duodenum positional variation and daily recalculations of duodenal dose metrics. Positional variation was quantified as the interfraction difference in Hausdorff distance from simulation baseline (ΔHD) between the GTV and proximal duodenal surface, or volume overlap between GTV and duodenum for cases with HD{sub 0}=0 (GTV abutting duodenum). Adaptation was considered indicated when daily positional variations enabled dose escalation to the target while maintaining duodenal constraints. Results: For fractions with ΔHD>0 (n=14, SBRT only), the mean interfraction duodenum dose decrease from simulation to treatment was 44±53 cGy (maximum 136 cGy). A correlation was found between ΔHD and dosimetric difference (R{sup 2}=0.82). No correlation was found between volume of overlap and dosimetric difference (R{sup 2}=0.31). For 89% of fractions, the duodenum remained overlapped with the target and the duodenal dose difference was negligible. The maximum observed indication for adaptation was for interfraction ΔHD=11.6 mm with potential for adaptive dose escalation of 136 cGy. Conclusion: This assessment showed that Hausdorff distance was a reasonable

TU-AB-BRA-11: Indications for Online Adaptive Radiotherapy Based On Dosimetric Consequences of Interfractional Pancreas-To-Duodenum Motion in MRI-Guided Pancreatic Radiotherapy

International Nuclear Information System (INIS)

Mittauer, K; Rosenberg, S; Geurts, M; Bassetti, M; Wojcieszynski, A; Harari, P; Labby, Z; Hill, P; Paliwal, B; Bayouth, J; Chen, I; Henke, L; Kashani, R; Parikh, P; Olsen, J

2016-01-01

Purpose: Dose limiting structures, such as the duodenum, render the treatment of pancreatic cancer challenging. In this multi-institutional study, we assess dosimetric differences caused by interfraction pancreas-to-duodenum motion using MR-IGRT to determine the potential impact of adaptive replanning. Methods: Ten patients from two institutions undergoing MRI-guided radiotherapy with conventional fractionation (n=5) or SBRT (n=5) for pancreatic cancer were included. Initial plans were limited by duodenal dose constraints of 50 Gy (0.5 cc)/31 Gy (0.1 cc) for conventional/SBRT with prescriptions of 30 Gy/5 fractions (SBRT) and 40–50 Gy/25 fractions (conventional). Daily volumetric MR images were acquired under treatment conditions on a clinical MR-IGRT system. The correlation was assessed between interfractional GTV-to-duodenum positional variation and daily recalculations of duodenal dose metrics. Positional variation was quantified as the interfraction difference in Hausdorff distance from simulation baseline (ΔHD) between the GTV and proximal duodenal surface, or volume overlap between GTV and duodenum for cases with HD_0=0 (GTV abutting duodenum). Adaptation was considered indicated when daily positional variations enabled dose escalation to the target while maintaining duodenal constraints. Results: For fractions with ΔHD>0 (n=14, SBRT only), the mean interfraction duodenum dose decrease from simulation to treatment was 44±53 cGy (maximum 136 cGy). A correlation was found between ΔHD and dosimetric difference (R"2=0.82). No correlation was found between volume of overlap and dosimetric difference (R"2=0.31). For 89% of fractions, the duodenum remained overlapped with the target and the duodenal dose difference was negligible. The maximum observed indication for adaptation was for interfraction ΔHD=11.6 mm with potential for adaptive dose escalation of 136 cGy. Conclusion: This assessment showed that Hausdorff distance was a reasonable metric to use to

Use of secondary phosphorescence for determination of the dose absorbed in dosimetric phosphors

CERN Document Server

Yaek, I V

2002-01-01

The measuring method of optically stimulated persistence (OSP) based on both the time division of the stimulating irradiation and luminescent response registration was applied for the radiation dosimetry. It was shown that the stimulation by the short-wave radiation crossing with spectrum of the dosimetric phosphor is possible. The spectrum of the stimulation of industry dosimetric phosphors was measured. The characteristics of the OSP registration for the phosphors which has manganese Mn sup 2 sup + as the activator is considered. Decay time of inner center luminescence is 40-50 ms. This method is used for the dosimetry of the natural quartzes to determine their age.

Dosimetric comparison between step-shoot intensity-modulated radiotherapy and volumetric-modulated arc therapy for upper thoracic and cervical esophageal carcinoma

Energy Technology Data Exchange (ETDEWEB)

Gao, Min; Li, Qilin; Ning, Zhonghua; Gu, Wendong; Huang, Jin; Mu, Jinming; Pei, Honglei, E-mail: hongleipei@126.com

2016-07-01

To compare and analyze the dosimetric characteristics of volumetric modulated arc therapy (VMAT) vs step-shoot intensity-modulated radiation therapy (sIMRT) for upper thoracic and cervical esophageal carcinoma. Single-arc VMAT (VMAT1), dual-arc VMAT (VMAT2), and 7-field sIMRT plans were designed for 30 patients with upper thoracic or cervical esophageal carcinoma. Planning target volume (PTV) was prescribed to 50.4 Gy in 28 fractions, and PTV1 was prescribed to 60 Gy in 28 fractions. The parameters evaluated included dose homogeneity and conformality, dose to organs at risk (OARs), and delivery efficiency. (1) In comparison to sIMRT, VMAT provided a systematic improvement in PTV1 coverage. The homogeneity index of VMAT1 was better than that of VMAT2. There were no significant differences among sIMRT, VMAT1, and VMAT2 in PTV coverage. (2) VMAT1 and VMAT2 reduced the maximum dose of spinal cord as compared with sIMRT (p < 0.05). The rest dose-volume characteristics of OARs were similar. (3) Monitor units of VMAT2 and VMAT1 were more than sIMRT. However, the treatment time of VMAT1, VMAT2, and sIMRT was (2.0 ± 0.2), (2.8 ± 0.3), and (9.8 ± 0.8) minutes, respectively. VMAT1 was the fastest, and the difference was statistically significant. In the treatment of upper thoracic and cervical esophageal carcinoma by the AXESSE linac, compared with 7-field sIMRT, VMAT showed better PTV1 coverage and superior spinal cord sparing. Single-arc VMAT had similar target volume coverage and the sparing of OAR to dual-arc VMAT, with shortest treatment time and highest treatment efficiency in the 3 kinds of plans.

An experimental comparison of conventional two-bank and novel four-bank dynamic MLC tracking

International Nuclear Information System (INIS)

Davies, G A; Clowes, P; McQuaid, D; Evans, P M; Webb, S; Poludniowski, G

2013-01-01

The AccuLeaf mMLC featuring four multileaf-collimator (MLC) banks has been used for the first time for an experimental comparison of conventional two-bank with novel four-bank dynamic MLC tracking of a two-dimensional sinusoidal respiratory motion. This comparison was performed for a square aperture, and for three conformal treatment apertures from clinical radiotherapy lung cancer patients. The system latency of this prototype tracking system was evaluated and found to be 1.0 s and the frequency at which MLC positions could be updated, 1 Hz, and therefore accurate MLC tracking of irregular patient motion would be difficult with the system in its current form. The MLC leaf velocity required for two-bank-MLC and four-bank-MLC tracking was evaluated for the apertures studied and a substantial decrease was found in the maximum MLC velocity required when four-banks were used for tracking rather than two. A dosimetric comparison of the two techniques was also performed and minimal difference was found between two-bank-MLC and four-bank-MLC tracking. The use of four MLC banks for dynamic MLC tracking is shown to be potentially advantageous for increasing the delivery efficiency compared with two-bank-MLC tracking where difficulties are encountered if large leaf shifts are required to track motion perpendicular to the direction of leaf travel. (paper)

Dosimetric verification for primary focal hypermetabolism of nasopharyngeal carcinoma patients treated with dynamic intensity-modulated radiation therapy.

Science.gov (United States)

Xin, Yong; Wang, Jia-Yang; Li, Liang; Tang, Tian-You; Liu, Gui-Hong; Wang, Jian-She; Xu, Yu-Mei; Chen, Yong; Zhang, Long-Zhen

2012-01-01

To make sure the feasibility with (18F)FDG PET/CT to guided dynamic intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma patients, by dosimetric verification before treatment. Chose 11 patients in III~IVA nasopharyngeal carcinoma treated with functional image-guided IMRT and absolute and relative dosimetric verification by Varian 23EX LA, ionization chamber, 2DICA of I'mRT Matrixx and IBA detachable phantom. Drawing outline and making treatment plan were by different imaging techniques (CT and (18F)FDG PET/CT). The dose distributions of the various regional were realized by SMART. The absolute mean errors of interest area were 2.39%±0.66 using 0.6 cc ice chamber. Results using DTA method, the average relative dose measurements within our protocol (3%, 3 mm) were 87.64% at 300 MU/min in all filed. Dosimetric verification before IMRT is obligatory and necessary. Ionization chamber and 2DICA of I'mRT Matrixx was the effective dosimetric verification tool for primary focal hyper metabolism in functional image-guided dynamic IMRT for nasopharyngeal carcinoma. Our preliminary evidence indicates that functional image-guided dynamic IMRT is feasible.

Patient-specific dosimetric endpoints based treatment plan quality control in radiotherapy

International Nuclear Information System (INIS)

Song, Ting; Zhou, Linghong; Staub, David; Chen, Mingli; Lu, Weiguo; Tian, Zhen; Jia, Xun; Li, Yongbao; Jiang, Steve B; Gu, Xuejun

2015-01-01

In intensity modulated radiotherapy (IMRT), the optimal plan for each patient is specific due to unique patient anatomy. To achieve such a plan, patient-specific dosimetric goals reflecting each patient’s unique anatomy should be defined and adopted in the treatment planning procedure for plan quality control. This study is to develop such a personalized treatment plan quality control tool by predicting patient-specific dosimetric endpoints (DEs). The incorporation of patient specific DEs is realized by a multi-OAR geometry-dosimetry model, capable of predicting optimal DEs based on the individual patient’s geometry. The overall quality of a treatment plan is then judged with a numerical treatment plan quality indicator and characterized as optimal or suboptimal. Taking advantage of clinically available prostate volumetric modulated arc therapy (VMAT) treatment plans, we built and evaluated our proposed plan quality control tool. Using our developed tool, six of twenty evaluated plans were identified as sub-optimal plans. After plan re-optimization, these suboptimal plans achieved better OAR dose sparing without sacrificing the PTV coverage, and the dosimetric endpoints of the re-optimized plans agreed well with the model predicted values, which validate the predictability of the proposed tool. In conclusion, the developed tool is able to accurately predict optimally achievable DEs of multiple OARs, identify suboptimal plans, and guide plan optimization. It is a useful tool for achieving patient-specific treatment plan quality control. (paper)

Dosimetric characterization of a 2-D array of 223 solid state detectors for daily morning checks in Tomo Therapy equipment; Caracterizacion dosimetrica de un arreglo 2D de 223 detectores de estado solido para verificaciones matutinas diarias en un equipo de Tomo Terapia

Energy Technology Data Exchange (ETDEWEB)

Reyes S, U.; Sosa A, M. [Universidad de Guanajuato, Division de Ciencias e Ingenieria, Lomas del Bosque No. 103, Col. Lomas del Campestre, 37150 Leon, Guanajuato (Mexico); Vega C, H. R., E-mail: uvaldoreyes@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

2015-10-15

Tomo Therapy is a new technique for the cancer treatment; however, the equipment must meet nearly all mechanical and dosimetric characteristics of a conventional linear accelerator for medical use. Daily quality controls are vital to the good operation of the equipment and thus guarantee excellent quality in the daily delivery of treatments. This paper presents the procedure of the dosimetric characterization of a two-dimensional array of 223 solid state detectors, called TomoDose of the Sun Nuclear Company. Dosimetric important criteria are established to perform these checks quickly and accurately. Dosimetric tests proposed are: repeatability, linearity, dependence of Sad and SSD. Some results are compared with readings of the ionization chamber Exradim A1SL. Finally the results of 30 consecutive days are presented to establish criteria for evidence of dose, field size, symmetry and flattening of the radiation beam on Tomo Therapy equipment. Expected values for daily verification are: Dose constancy of 194.89 c Gy, σ= 1.31 c Gy, symmetry in the X axis of -0.19 %, σ=0.08 %, symmetry in the Y axis of 1.66 %, σ= 0.05 %, flattened in the X axis of 25.71 %, σ= 0.05 % and flattened in the Y axis of 6.41 %, σ= 10.23 %. Field sizes obtained were 40.45 cm in the X axis and 5.10 on the Y axis, with standard deviations of 0.02 cm and 0.01 cm, respectively. TomoDose dosimetric values, compared to the values obtained with ionization chamber, presented differences smaller than 2%. (Author)

3D-Conformal Versus Intensity-Modulated Postoperative Radiotherapy of Vaginal Vault: A Dosimetric Comparison

International Nuclear Information System (INIS)

Cilla, Savino; Macchia, Gabriella; Digesu, Cinzia; Deodato, Francesco; Romanella, Michele; Ferrandina, Gabriella; Padula, Gilbert; Picardi, Vincenzo; Scambia, Giovanni; Piermattei, Angelo; Morganti, Alessio Giuseppe

2010-01-01

We evaluated a step-and-shoot IMRT plan in the postoperative irradiation of the vaginal vault compared with equispaced beam arrangements (3-5) 3D-radiotherapy (RT) optimized plans. Twelve patients were included in this analysis. Four plans for each patient were compared in terms of dose-volume histograms, homogeneity index (HI), and conformity index (CI): (1) 3 equispaced beam arrangement 3D-RT; (2) 4 equispaced beam arrangement 3D-RT; (3) 5 equispaced beam arrangement 3D-RT; (4) step-and-shoot IMRT technique. CI showed a good discrimination between the four plans. The mean scores of CI were 0.58 (range: 0.38-0.67) for the 3F-CRT plan, 0.58 (range: 0.41-0.66) for 4F-CRT, 0.62 (range: 0.43-0.68) for 5F-CRT and 0.69 (range: 0.58-0.78) for the IMRT plan. A significant improvement of the conformity was reached by the IMRT plan (p mean , V90%, V95%, V100% was recorded for rectal and bladder irradiation with the IMRT plan. Surprisingly, IMRT supplied a significant dose reduction also for rectum and bladder V30% and V50%. A significant dosimetric advantage of IMRT over 3D-RT in the adjuvant treatment of vaginal vault alone in terms of treatment conformity and rectum and bladder sparing is shown.

Rectal dose assessment in patients submitted to high-dose-rate brachytherapy for uterine cervix cancer; Avaliacao da dose no reto em pacientes submetidas a braquiterapia de alta taxa de dose para o tratamento do cancer do colo uterino

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Jetro Pereira de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Faculdade de Medicina; Rosa, Luiz Antonio Ribeiro da [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)], e-mail: lrosa@ird.gov.br; Batista, Delano Valdivino Santos; Bardella, Lucia Helena [Instituto Nacional de Cancer (INCA), Rio de Janeiro, RJ (Brazil). Unit of Medical Physics; Carvalho, Arnaldo Rangel [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. of Thermoluminescent Dosimetry

2009-03-15

Objective: The present study was aimed at developing a thermoluminescent dosimetric system capable of assessing the doses delivered to the rectum of patients submitted to high-dose-rate brachytherapy for uterine cervix cancer. Materials and methods: LiF:Mg,Ti,Na powder was the thermoluminescent material utilized for evaluating the rectal dose. The powder was divided into small portions (34 mg) which were accommodated in a capillary tube. This tube was placed into a rectal probe that was introduced into the patient's rectum. Results: The doses delivered to the rectum of six patients submitted to high-dose-rate brachytherapy for uterine cervix cancer evaluated by means of thermoluminescent dosimeters presented a good agreement with the planned values based on two orthogonal (anteroposterior and lateral) radiographic images of the patients. Conclusion: The thermoluminescent dosimetric system developed in the present study is simple and easy to be utilized as compared to other rectal dosimetry methods. The system has shown to be effective in the evaluation of rectal doses in patients submitted to high-dose-rate brachytherapy for uterine cervix cancer. (author)

Dosimetric characterization of the Exradin W1 plastic scintillator detector through comparison with an in-house developed scintillator system. / Beierholm, Anders Ravnsborg

DEFF Research Database (Denmark)

Beierholm, Anders Ravnsborg; Behrens, Claus Flensted; Andersen, Claus E.

2014-01-01

method, but differing primarily in the signal detection hardware. The two systems were compared with respect to essential dosimetric properties, with the purpose of testing their performance under conditions less well discussed in the literature. A Farmer ionization chamber was used as the primary...... is therefore advised if using either system for measurements in large fields or under circumstances where the fibre irradiation geometry is unfavourable. Measurements of reference dose to water yielded differences up to 1.5% when compared with the Farmer ionization chamber for all investigated beam qualities....

Portal imaging practice patterns of children's oncology group institutions: Dosimetric assessment and recommendations for minimizing unnecessary exposure

International Nuclear Information System (INIS)

Olch, Arthur J.; Geurts, Mark; Thomadsen, Bruce; Famiglietti, Robin; Chang, Eric L.

2007-01-01

Purpose: To determine and analyze the dosimetric consequences of current portal imaging practices for pediatric patients, and make specific recommendations for reducing exposure from portal imaging procedures. Methods and Materials: A survey was sent to approximately 250 Children's Oncology Group (COG) member institutions asking a series of questions about their portal imaging practices. Three case studies are presented with dosimetric analysis to illustrate the magnitude of unintended dose received by nontarget tissues using the most common techniques from the survey. Results: The vast majority of centers use double-exposure portal image techniques with a variety of open field margins. Only 17% of portal images were obtained during treatment, and for other imaging methods, few centers subtract monitor units from the treatment delivery. The number of monitor units used was nearly the same regardless of imager type, including electronic portal imaging devices. Eighty-six percent imaged all fields the first week and 17% imaged all fields every week. An additional 1,112 cm 3 of nontarget tissue received 1 Gy in one of the example cases. Eight new recommendations are made, which will lower nontarget radiation doses with minimal impact on treatment verification accuracy. Conclusion: Based on the survey, changes can be made in portal imaging practices that will lower nontarget doses. It is anticipated that treatment verification accuracy will be minimally affected. Specific recommendations made to decrease the imaging dose and help lower the rate of radiation-induced secondary cancers in children are proposed for inclusion in future COG protocols using radiation therapy

Monte Carlo generation of dosimetric parameters for eye plaque dosimetry

International Nuclear Information System (INIS)

Cutajar, D.L.; Green, J.A.; Guatelli, S.; Rosenfeld, A.B.

2010-01-01

Full text: The Centre for Medical Radiation Physics have undertaken the dcvelopment of a quality assurance tool, using silicon pixelated detectors, for the calibration of eye plaques prior to insertion. Dosimetric software to correlate the measured and predicted dose rates has been constructed. The dosimetric parameters within the software, for both 1-125 and Ru-I 06 based eye plaques, were optimised using the Geant4 Monte Carlo toolkit. Methods For 1-125 based plaques, an novel application was developed to generate TG-43 parameters for any seed input. TG-43 parameters were generated for an Oncura model 6711 seed, with data points every millimetre up to 25 mm in the radial direction, and every 5 degrees in polar angle, and correlated to published data. For the Ru106 based plaques, an application was developed to generate dose rates about a Bebig model CCD plaque. Toroids were used to score the deposited dose, taking advantage of the cylindrical symmetry of the plaque, with radii in millimetre increments up to 25 mm, and depth from the plaque surface in millimetre increments up to 25 mm. Results TheTG43 parameters generated for the 6711 seed correlate well with published TG43 data at the given intervals, with radial dose function within 3%, and anisotropy function within 5% for angles greater than 30 degrees. The Ru-l 06 plaque data correlated well with the Bebig protocol of measurement. Conclusion Geant4 is a useful Monte Carlo tool for the generation of dosimetric data for eye plaque dosimetry. which may improve the quality assurance of eye plaque treatment. (author)

Propagation of registration uncertainty during multi-fraction cervical cancer brachytherapy

Science.gov (United States)

Amir-Khalili, A.; Hamarneh, G.; Zakariaee, R.; Spadinger, I.; Abugharbieh, R.

2017-10-01

Multi-fraction cervical cancer brachytherapy is a form of image-guided radiotherapy that heavily relies on 3D imaging during treatment planning, delivery, and quality control. In this context, deformable image registration can increase the accuracy of dosimetric evaluations, provided that one can account for the uncertainties associated with the registration process. To enable such capability, we propose a mathematical framework that first estimates the registration uncertainty and subsequently propagates the effects of the computed uncertainties from the registration stage through to the visualizations, organ segmentations, and dosimetric evaluations. To ensure the practicality of our proposed framework in real world image-guided radiotherapy contexts, we implemented our technique via a computationally efficient and generalizable algorithm that is compatible with existing deformable image registration software. In our clinical context of fractionated cervical cancer brachytherapy, we perform a retrospective analysis on 37 patients and present evidence that our proposed methodology for computing and propagating registration uncertainties may be beneficial during therapy planning and quality control. Specifically, we quantify and visualize the influence of registration uncertainty on dosimetric analysis during the computation of the total accumulated radiation dose on the bladder wall. We further show how registration uncertainty may be leveraged into enhanced visualizations that depict the quality of the registration and highlight potential deviations from the treatment plan prior to the delivery of radiation treatment. Finally, we show that we can improve the transfer of delineated volumetric organ segmentation labels from one fraction to the next by encoding the computed registration uncertainties into the segmentation labels.

Risk factors for pericardial effusion after chemoradiotherapy for thoracic esophageal cancer-comparison of four-field technique and traditional two opposed fields technique.

Science.gov (United States)

Takata, Noriko; Kataoka, Masaaki; Hamamoto, Yasushi; Tsuruoka, Shintaro; Kanzaki, Hiromitsu; Uwatsu, Kotaro; Nagasaki, Kei; Mochizuki, Teruhito

2018-04-11

Pericardial effusion is an important late toxicity after concurrent chemoradiotherapy (CCRT) for locally advanced esophageal cancer. We investigated the clinical and dosimetric factors that were related to pericardial effusion among patients with thoracic esophageal cancer who were treated with definitive CCRT using the two opposed fields technique (TFT) or the four-field technique (FFT), as well as the effectiveness of FFT. During 2007-2015, 169 patients with middle and/or lower thoracic esophageal cancer received definitive CCRT, and 94 patients were evaluable (51 FFT cases and 43 TFT cases). Pericardial effusion was observed in 74 patients (79%) and appeared at 1-18.5 months (median: 5.25 months) after CCRT. The 1-year incidences of pericardial effusions were 73.2% and 76.7% in the FFT and TFT groups, respectively (P = 0.6395). The mean doses to the pericardium were 28.6 Gy and 31.8 Gy in the FFT and TFT groups, respectively (P = 0.0259), and the V40 Gy proportions were 33.5% and 48.2% in the FFT and TFT groups, respectively (P effusion was not observed in patients with a pericardial V40 Gy of effusion after CCRT were similar in both groups. As symptomatic pericardial effusion was not observed in patients with a pericardial V40 Gy of effusion.