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Sample records for critical volume dose

  1. Dose-volume analysis of target volume and critical structures in computed tomography image-based multicatheter high-dose-rate interstitial brachytherapy for head and neck cancer

    Directory of Open Access Journals (Sweden)

    Hironori Akiyama

    2017-12-01

    Full Text Available Purpose : To evaluate dose-volume relationships of target volume and critical structures in computed tomography (CT image-based brachytherapy for head and neck cancer. Material and methods : Thirty-seven patients with mobile tongue, floor of mouth, and base of tongue cancer treated with brachytherapy (post-operative alone and as a boost after external beam radiotherapy [EBRT], or definitive alone or as a boost after EBRT were selected. Treatment plans were made using post-implant CT images. The fractionation schedule was 7-15 × 3-5 Gy for post-operative (with or without EBRT, 14-15 × 3 Gy for definitive alone, and 5-10 × 3 Gy for boost treatments. For the target volume, V 100 , D 90 , and dose non-uniformity ratio (DNR were calculated. For the mandible, spinal cord and salivary glands doses to specified volumes were reported. Results : The median values of V 100 and D 90 were 89.9% and 99.9%, respectively; the median values of DNR was 0.46. The median D 2cm 3 of the mandible and spinal cord were 48.3% and 5.8%, respectively. The ipsilateral median D 2cm 3 of parotid and submandibular glands were 6.4% and 12.5%, whereas on the contralateral side, the corresponding values were 5.3% and 7.0%, respectively. Conclusions : Using conformal treatment planning, it was desirable to keep the dose to the mandible, spinal cord, and salivary glands at an acceptable level. The quantitative plan evaluation may help us find correlations between dosimetric parameters and clinical outcome, which may lead to improve the quality of the treatment, but it requires longer follow-up and results from other studies.

  2. Empirical evaluation of cell critical volume dose vs. cell response function for pink mutations in tradescantia

    International Nuclear Information System (INIS)

    Varma, M.N.; Bond, V.P.

    1982-01-01

    Microdosimetric spectra for 0.43, 1.8, and 14.7 MeV neutrons, and for 215 kVp x rays and 1250 keV gammas were used in conjunction with relative biological effectiveness (RBE) values for pink mutations in Tradescantia to obtain an effectiveness function (i.e., a cell critical volume dose vs. cell response function). This effectiveness function (or hit size weighting function) provides the probability of inducing a biological effect of interest (in the present study, pink mutations in Tradescantia) as a function of lineal energy density y. In a preliminary analysis the critical value of y above which pink mutations are seen was 4.5 keV/μm, and the value of y at which the probability reaches unity was 115 keV/μm. Idealized but approximate event size distributions for mono-LET particles ranging from 10 to 5000 keV/μm were generated, and these distributions were weighted by the effectiveness function to determine the pink mutation frequencies. Results are compared with measured pink mutation frequencies for 11 keV/μm ( 12 C) and 31 keV/μm ( 20 Ne) ions

  3. Critical Combinations of Radiation Dose and Volume Predict Intelligence Quotient and Academic Achievement Scores After Craniospinal Irradiation in Children With Medulloblastoma

    International Nuclear Information System (INIS)

    Merchant, Thomas E.; Schreiber, Jane E.; Wu, Shengjie; Lukose, Renin; Xiong, Xiaoping; Gajjar, Amar

    2014-01-01

    Purpose: To prospectively follow children treated with craniospinal irradiation to determine critical combinations of radiation dose and volume that would predict for cognitive effects. Methods and Materials: Between 1996 and 2003, 58 patients (median age 8.14 years, range 3.99-20.11 years) with medulloblastoma received risk-adapted craniospinal irradiation followed by dose-intense chemotherapy and were followed longitudinally with multiple cognitive evaluations (through 5 years after treatment) that included intelligence quotient (estimated intelligence quotient, full-scale, verbal, and performance) and academic achievement (math, reading, spelling) tests. Craniospinal irradiation consisted of 23.4 Gy for average-risk patients (nonmetastatic) and 36-39.6 Gy for high-risk patients (metastatic or residual disease >1.5 cm 2 ). The primary site was treated using conformal or intensity modulated radiation therapy using a 2-cm clinical target volume margin. The effect of clinical variables and radiation dose to different brain volumes were modeled to estimate cognitive scores after treatment. Results: A decline with time for all test scores was observed for the entire cohort. Sex, race, and cerebrospinal fluid shunt status had a significant impact on baseline scores. Age and mean radiation dose to specific brain volumes, including the temporal lobes and hippocampi, had a significant impact on longitudinal scores. Dichotomized dose distributions at 25 Gy, 35 Gy, 45 Gy, and 55 Gy were modeled to show the impact of the high-dose volume on longitudinal test scores. The 50% risk of a below-normal cognitive test score was calculated according to mean dose and dose intervals between 25 Gy and 55 Gy at 10-Gy increments according to brain volume and age. Conclusions: The ability to predict cognitive outcomes in children with medulloblastoma using dose-effects models for different brain subvolumes will improve treatment planning, guide intervention, and help estimate

  4. Critical Combinations of Radiation Dose and Volume Predict Intelligence Quotient and Academic Achievement Scores After Craniospinal Irradiation in Children With Medulloblastoma

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    Merchant, Thomas E., E-mail: thomas.merchant@stjude.org [Division of Radiation Oncology, St. Jude Children' s Research Hospital, Memphis, Tennessee (United States); Schreiber, Jane E. [Department of Psychology, St. Jude Children' s Research Hospital, Memphis, Tennessee (United States); Wu, Shengjie [Department of Biostatistcs, St. Jude Children' s Research Hospital, Memphis, Tennessee (United States); Lukose, Renin [Division of Radiation Oncology, St. Jude Children' s Research Hospital, Memphis, Tennessee (United States); Xiong, Xiaoping [Department of Biostatistcs, St. Jude Children' s Research Hospital, Memphis, Tennessee (United States); Gajjar, Amar [Department of Oncology, St. Jude Children' s Research Hospital, Memphis, Tennessee (United States)

    2014-11-01

    Purpose: To prospectively follow children treated with craniospinal irradiation to determine critical combinations of radiation dose and volume that would predict for cognitive effects. Methods and Materials: Between 1996 and 2003, 58 patients (median age 8.14 years, range 3.99-20.11 years) with medulloblastoma received risk-adapted craniospinal irradiation followed by dose-intense chemotherapy and were followed longitudinally with multiple cognitive evaluations (through 5 years after treatment) that included intelligence quotient (estimated intelligence quotient, full-scale, verbal, and performance) and academic achievement (math, reading, spelling) tests. Craniospinal irradiation consisted of 23.4 Gy for average-risk patients (nonmetastatic) and 36-39.6 Gy for high-risk patients (metastatic or residual disease >1.5 cm{sup 2}). The primary site was treated using conformal or intensity modulated radiation therapy using a 2-cm clinical target volume margin. The effect of clinical variables and radiation dose to different brain volumes were modeled to estimate cognitive scores after treatment. Results: A decline with time for all test scores was observed for the entire cohort. Sex, race, and cerebrospinal fluid shunt status had a significant impact on baseline scores. Age and mean radiation dose to specific brain volumes, including the temporal lobes and hippocampi, had a significant impact on longitudinal scores. Dichotomized dose distributions at 25 Gy, 35 Gy, 45 Gy, and 55 Gy were modeled to show the impact of the high-dose volume on longitudinal test scores. The 50% risk of a below-normal cognitive test score was calculated according to mean dose and dose intervals between 25 Gy and 55 Gy at 10-Gy increments according to brain volume and age. Conclusions: The ability to predict cognitive outcomes in children with medulloblastoma using dose-effects models for different brain subvolumes will improve treatment planning, guide intervention, and help

  5. Optimization of radiotherapy to target volumes with concave outlines: target-dose homogenization and selective sparing of critical structures by constrained matrix inversion

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    Colle, C.; Van den Berge, D.; De Wagter, C.; Fortan, L.; Van Duyse, B.; De Neve, W.

    1995-12-01

    The design of 3D-conformal dose distributions for targets with concave outlines is a technical challenge in conformal radiotherapy. For these targets, it is impossible to find beam incidences for which the target volume can be isolated from the tissues at risk. Commonly occurring examples are most thyroid cancers and the targets located at the lower neck and upper mediastinal levels related to some head and neck. A solution to this problem was developed, using beam intensity modulation executed with a multileaf collimator by applying a static beam-segmentation technique. The method includes the definition of beam incidences and beam segments of specific shape as well as the calculation of segment weights. Tests on Sherouse`s GRATISTM planning system allowed to escalate the dose to these targets to 65-70 Gy without exceeding spinal cord tolerance. Further optimization by constrained matrix inversion was investigated to explore the possibility of further dose escalation.

  6. When treating prostate cancer with three-dimensional conformal radiation therapy the impact of bladder filling status on the volume and integral dose distribution of the target and critical organs should be kept in mind

    International Nuclear Information System (INIS)

    Liu Yueping; Liu Xinfan; Li Yexiong; Guang Ying

    2007-01-01

    Objective: In prostate cancer treated with three-dimensional conformal radiation therapy (3DCRT), we tried to prospectively assess the impact of the filling status of bladder on the volume and the integral dose distribution to the target and surrounding critical organs. Methods: Ten patients with stage T1-T2N0M0 prostate cancer were studied. All patients received 3DCRT to the prostate and inferior seminal vesicle. One hour before CT simulation, the bladder was first voided, and then 400 ml of oral contrast solution was given at every half hour before the CT scan. Urethral catheterization was used for voiding or distending the bladder. When distending the bladder, 250-300 ml of contrast was injected into the bladder with the patient fixed at the supine position. Two sets of transverse images were taken for the whole pelvis in empty and full bladder. After the target and critical organs (bladder, rectum, pelvic small bowel, and femoral heads) were contoured, a treatment plan of three-dimensional conformal radiotherapy was made using the CMS Focus-Xio treatment planning system. The volume and mean doses of CTV, PTV, rectum, bladder, femoral heads, and small bowel with the bladder empty and full were evaluated. The percentage of volume which received 50 Gy in the rectum and bladder, 30 Gy in the femoral heads, and the maximal dose to the pelvic small bowel were also assessed . The variability of volume and dose distribution in these targets or organs was compared between the empty and full bladder status. Results: Comparing to the bladder empty status, full bladder led to a mean increase of 499% in the bladder volume, (67±9) ml and (336±48) ml (P=0.000), respectively. No volume change was found in the CTV, PTV, rectum, femoral heads and pel- vic small bowel(P=0.153,0.501,0.929,0.771,0.081). The mean dose to the bladder in full status was only 35% of that in empty status, (1501±201 ) cGy and (4267±216) cGy(P =0.000), respectively. The mean dose to the pelvic small

  7. Fast in vivo volume dose reconstruction via reference dose perturbation

    International Nuclear Information System (INIS)

    Lu, Weiguo; Chen, Mingli; Mo, Xiaohu; Parnell, Donald; Olivera, Gustavo; Galmarini, Daniel

    2014-01-01

    Purpose: Accurate on-line reconstruction of in-vivo volume dose that accounts for both machine and patient discrepancy is not clinically available. We present a simple reference-dose-perturbation algorithm that reconstructs in-vivo volume dose fast and accurately. Methods: We modelled the volume dose as a function of the fluence map and density image. Machine (output variation, jaw/leaf position errors, etc.) and patient (setup error, weight loss, etc.) discrepancies between the plan and delivery were modelled as perturbation of the fluence map and density image, respectively. Delivered dose is modelled as perturbation of the reference dose due to change of the fluence map and density image. We used both simulated and clinical data to validate the algorithm. The planned dose was used as the reference. The reconstruction was perturbed from the reference and accounted for output-variations and the registered daily image. The reconstruction was compared with the ground truth via isodose lines and the Gamma Index. Results: For various plans and geometries, the volume doses were reconstructed in few seconds. The reconstruction generally matched well with the ground truth. For the 3%/3mm criteria, the Gamma pass rates were 98% for simulations and 95% for clinical data. The differences mainly appeared on the surface of the phantom/patient. Conclusions: A novel reference-dose-perturbation dose reconstruction model is presented. The model accounts for machine and patient discrepancy from planning. The algorithm is simple, fast, yet accurate, which makes online in-vivo 3D dose reconstruction clinically feasible.

  8. Conversion of dose volume constraints to dose limits

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    Dai Jianrong [Department of Radiological Science, St Jude Children' s Research Hospital, Memphis, TN 38105 (United States); Zhu Yunping [Department of Radiological Science, St Jude Children' s Research Hospital, Memphis, TN 38105 (United States)

    2003-12-07

    The purpose of this study is to introduce two techniques for converting dosevolume constraints to dose limits for treatment planning optimization, and to evaluate their performance. The first technique, called dose-sorting, is based on the assumption that higher dose limits should be assigned to the constraint points receiving higher doses, and vice versa. The second technique, the hybrid technique, is a hybrid of the dose-sorting technique and the mixed integer linear programming (MILP) technique. Among all constraint points in an organ at risk, the dose limits for the points far from a dosevolume constraint are determined by dose-sorting, while the dose limits for the points close to a dosevolume constraint are determined by MILP. We evaluated the performance of the two new techniques for one treatment geometry by comparing them with the MILP technique. The dose-sorting technique had a high probability of finding the global optimum when no more than three organs at risk have dose-volume constraints. It was much faster than the MILP technique. The hybrid technique always found the global optimum when the MILP percentage (the percentage of constraint points for which the dose limits are determined by the MILP technique) was large enough, but its computation time increased dramatically with the MILP percentage. In conclusion, the dose-sorting technique and the hybrid technique with a low MILP percentage are clinically feasible.

  9. Critical Qualitative Research Reader. Critical Qualitative Research. Volume 2

    Science.gov (United States)

    Steinberg, Shirley R., Ed.; Cannella, Gaile S., Ed.

    2012-01-01

    This volume of transformed research utilizes an activist approach to examine the notion that nothing is apolitical. Research projects themselves are critically examined for power orientations, even as they are used to address curricular problems and educational or societal issues. Philosophical perspectives that have facilitated an understanding…

  10. Radiation dose-volume effects in the lung

    DEFF Research Database (Denmark)

    Marks, Lawrence B; Bentzen, Soren M; Deasy, Joseph O

    2010-01-01

    The three-dimensional dose, volume, and outcome data for lung are reviewed in detail. The rate of symptomatic pneumonitis is related to many dosimetric parameters, and there are no evident threshold "tolerance dose-volume" levels. There are strong volume and fractionation effects.......The three-dimensional dose, volume, and outcome data for lung are reviewed in detail. The rate of symptomatic pneumonitis is related to many dosimetric parameters, and there are no evident threshold "tolerance dose-volume" levels. There are strong volume and fractionation effects....

  11. A theoretical approach to the problem of dose-volume constraint estimation and their impact on the dose-volume histogram selection

    International Nuclear Information System (INIS)

    Schinkel, Colleen; Stavrev, Pavel; Stavreva, Nadia; Fallone, B. Gino

    2006-01-01

    This paper outlines a theoretical approach to the problem of estimating and choosing dose-volume constraints. Following this approach, a method of choosing dose-volume constraints based on biological criteria is proposed. This method is called ''reverse normal tissue complication probability (NTCP) mapping into dose-volume space'' and may be used as a general guidance to the problem of dose-volume constraint estimation. Dose-volume histograms (DVHs) are randomly simulated, and those resulting in clinically acceptable levels of complication, such as NTCP of 5±0.5%, are selected and averaged producing a mean DVH that is proven to result in the same level of NTCP. The points from the averaged DVH are proposed to serve as physical dose-volume constraints. The population-based critical volume and Lyman NTCP models with parameter sets taken from literature sources were used for the NTCP estimation. The impact of the prescribed value of the maximum dose to the organ, D max , on the averaged DVH and the dose-volume constraint points is investigated. Constraint points for 16 organs are calculated. The impact of the number of constraints to be fulfilled based on the likelihood that a DVH satisfying them will result in an acceptable NTCP is also investigated. It is theoretically proven that the radiation treatment optimization based on physical objective functions can sufficiently well restrict the dose to the organs at risk, resulting in sufficiently low NTCP values through the employment of several appropriate dose-volume constraints. At the same time, the pure physical approach to optimization is self-restrictive due to the preassignment of acceptable NTCP levels thus excluding possible better solutions to the problem

  12. Defining bowel dose volume constraints for bladder radiotherapy treatment planning.

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    McDonald, F; Waters, R; Gulliford, S; Hall, E; James, N; Huddart, R A

    2015-01-01

    Increases to radiotherapy dose are constrained by normal tissue effects. The relationship between bowel dose volume data and late bowel toxicity in patients with muscle-invasive bladder cancer treated with radical radiotherapy was assessed. The bowel was contoured retrospectively on radiotherapy plans of 47 patients recruited to the BC2001 trial (CRUK/01/004). The relationship between bowel volume at various dose levels and prospectively collected late bowel toxicity was explored. Fifteen per cent and 6% of patients experienced grade 1 and grade 2 or more late bowel toxicity, respectively. The mean bowel volume was significantly less at doses ≥50 Gy in those treated with reduced high dose volume radiotherapy compared with standard radiotherapy. The probability of late bowel toxicity increased as bowel volume increased (P ≤ 0.05 for dose levels 30-50 Gy). No grade 2 or more late bowel toxicity was observed in patients with bowel volumes under the thresholds given in the model that predict for 25% probability of late bowel toxicity. There is a dose volume effect for late bowel toxicity in radical bladder radiotherapy. We have modelled the probability of late bowel toxicity from absolute bowel volumes to guide clinicians in assessing radical bladder radiotherapy plans. Thresholds predicting for a 25% probability of late bowel toxicity are proposed as dose volume constraints. Copyright © 2014. Published by Elsevier Ltd.

  13. Volume correction factor in time dose relationships in brachytherapy

    International Nuclear Information System (INIS)

    Supe, S.J.; Sasane, J.B.

    1987-01-01

    Paterson's clinical data about the maximum tolerance doses for various volumes of interstitial implants with Ra-226 delivered in seven days was made use of in deriving volume correction factors for TDF and CRE concepts respectively for brachytherapy. The derived volume correction factors for TDF and for CRE differ fromthe one assumed for CRE by Kirk et al. and implied for TDF by Goitein. A normalising volume of 70 cc has been suggested for both CRE and TDF concepts for brachytherapy. A table showing the volume corrected TDF is presented for various volumes and dose rates for continuous irradiation. The use of this table is illustrated with examples. (orig.) [de

  14. Dose, time and volume effects in interstitial radiation therapy

    International Nuclear Information System (INIS)

    Burgers, J.M.V.

    1982-01-01

    This study presents the main features and uncertainties of interstitial therapy and was undertaken to examine whether differences could be found in different clinical situations treated by interstitial implants with removable sources, that were not simply related to dose. In chapter 2, dating from 1978, continuous low dose rate irradiation is discussed from the radiobiological point of view together with some points related to variation in dose rate. A benefit of continuous low dose rate irradiation could be surmised in a few situations with special cell-kinetic properties. The problem of dose specification, the sharp dose gradient and other volume characteristics are discussed in chapter 3. Possible adjustments to variations in dose rate are discussed in chapter 4. The clinical material is reviewed in chapter 5, including aspects of dose specification, dose fall-off and variation in dose rate. The general discussion and conclusions are given in chapter 6. (Auth.)

  15. Dose volume assessment of high dose rate 192IR endobronchial implants

    International Nuclear Information System (INIS)

    Cheng, B. Saw; Korb, Leroy J.; Pawlicki, Todd; Wu, Andrew

    1996-01-01

    Purpose: To study the dose distributions of high dose rate (HDR) endobronchial implants using the dose nonuniformity ratio (DNR) and three volumetric irradiation indices. Methods and Materials: Multiple implants were configured by allowing a single HDR 192 Ir source to step through a length of 6 cm along an endobronchial catheter. Dwell times were computed to deliver a dose of 5 Gy to points 1 cm away from the catheter axis. Five sets of source configurations, each with different dwell position spacings from 0.5 to 3.0 cm, were evaluated. Three-dimensional (3D) dose distributions were then generated for each source configuration. Differential and cumulative dose-volume curves were generated to quantify the degree of target volume coverage, dose nonuniformity within the target volume, and irradiation of tissues outside the target volume. Evaluation of the implants were made using the DNR and three volumetric irradiation indices. Results: The observed isodose distributions were not able to satisfy all the dose constraints. The ability to optimally satisfy the dose constraints depended on the choice of dwell position spacing and the specification of the dose constraint points. The DNR and irradiation indices suggest that small dwell position spacing does not result in a more homogeneous dose distribution for the implant. This study supports the existence of a relationship between the dwell position spacing and the distance from the catheter axis to the reference dose or dose constraint points. Better dose homogeneity for an implant can be obtained if the spacing of the dwell positions are about twice the distance from the catheter axis to the reference dose or dose constraint points

  16. Dose-volume effects in rat thoracolumbar spinal cord: the effects of nonuniform dose distribution.

    Science.gov (United States)

    Philippens, Mariëlle E P; Pop, Lucas A M; Visser, Andries G; van der Kogel, Albert J

    2007-09-01

    To investigate dose-volume effects in rat spinal cord irradiated with nonuniform dose distributions and to assess regional differences in radiosensitivity. A total of 106 rats divided into three groups were irradiated with (192)Ir gamma-rays at a high dose rate. The groups were irradiated with one, two, or six catheters distributed around the thoracolumbar spinal cord to create different dose distributions. After irradiation, the animals were tested for motor function for 9 months. The response was defined as motor dysfunction and WM or nerve root necrosis. Dose-response data were analyzed with a probit analysis as function of the dose level at a percentage of the volume (D(%)) and with different normal tissue complication probability models. Additionally, the histologic responses of the individual dose voxels were analyzed after registration with the histologic sections. The probit analysis at D(24) (24% of the volume) gave the best fit results. In addition, the Lyman Kutcher Burman model and the relative seriality model showed acceptable fits, with volume parameters of 0.17 and 0.53, respectively. The histology-based analysis revealed a lower radiosensitivity for the dorsal (50% isoeffective dose [ED(50)] = 32.3) and lateral WM (ED(50) = 33.7 Gy) compared with the dorsal (ED(50) = 25.9 Gy) and ventral nerve roots (ED(50) = 24.1 Gy). For this nonuniform irradiation, the spinal cord did not show typical serial behavior. No migration terms were needed for an acceptable fit of the dose-response curves. A higher radiosensitivity for the lumbar nerve roots than for the thoracic WM was found.

  17. Dose evaluation of organs at risk (OAR) cervical cancer using dose volume histogram (DVH) on brachytherapy

    Science.gov (United States)

    Arif Wibowo, R.; Haris, Bambang; Inganatul Islamiyah, dan

    2017-05-01

    Brachytherapy is one way to cure cervical cancer. It works by placing a radioactive source near the tumor. However, there are some healthy tissues or organs at risk (OAR) such as bladder and rectum which received radiation also. This study aims to evaluate the radiation dose of the bladder and rectum. There were 12 total radiation dose data of the bladder and rectum obtained from patients’ brachytherapy. The dose of cervix for all patients was 6 Gy. Two-dimensional calculation of the radiation dose was based on the International Commission on Radiation Units and Measurements (ICRU) points or called DICRU while the 3-dimensional calculation derived from Dose Volume Histogram (DVH) on a volume of 2 cc (D2cc). The radiation dose of bladder and rectum from both methods were analysed using independent t test. The mean DICRU of bladder was 4.33730 Gy and its D2cc was4.78090 Gy. DICRU and D2cc bladder did not differ significantly (p = 0.144). The mean DICRU of rectum was 3.57980 Gy and 4.58670 Gy for D2cc. The mean DICRU of rectum differed significantly from D2cc of rectum (p = 0.000). The three-dimensional method radiation dose of the bladder and rectum was higher than the two-dimensional method with ratios 1.10227 for bladder and 1.28127 for rectum. The radiation dose of the bladder and rectum was still below the tolerance dose. Two-dimensional calculation of the bladder and rectum dose was lower than three-dimension which was more accurate due to its calculation at the whole volume of the organs.

  18. Multiplexed Dosing Assays by Digitally Definable Hydrogel Volumes

    DEFF Research Database (Denmark)

    Faralli, Adele; Melander, Fredrik; Larsen, Esben Kjær Unmack

    2016-01-01

    Stable and low-cost multiplexed drug sensitivity assays using small volumes of cells or tissue are in demand for personalized medicine, including patientspecific combination chemotherapy. Spatially defined projected light photopolymerization of hydrogels with embedded active compounds is introduc...... compounds. Further control of the dosing process is demonstrated by liposomal encapsulation of oxaliplatin, stable embedding of the liposomes in hydrogels for more than 3 months, and heat-triggered complete release of the loaded oxaliplatin....

  19. A dose-volume-based tool for evaluating and ranking IMRT treatment plans.

    Science.gov (United States)

    Miften, Moyed M; Das, Shiva K; Su, Min; Marks, Lawrence B

    2004-01-01

    External beam radiotherapy is commonly used for patients with cancer. While tumor shrinkage and palliation are frequently achieved, local control and cure remain elusive for many cancers. With regard to local control, the fundamental problem is that radiotherapy-induced normal tissue injury limits the dose that can be delivered to the tumor. While intensity-modulated radiation therapy (IMRT) allows for the delivery of higher tumor doses and the sparing of proximal critical structures, multiple competing plans can be generated based on dosimetric and/or biological constraints that need to be considered/compared. In this work, an IMRT treatment plan evaluation and ranking tool, based on dosimetric criteria, is presented. The treatment plan with the highest uncomplicated target conformity index (TCI+) is ranked at the top. The TCI+ is a dose-volume-based index that considers both a target conformity index (TCI) and a normal tissue-sparing index (NTSI). TCI+ is designed to assist in the process of judging the merit of a clinical treatment plan. To demonstrate the utility of this tool, several competing lung and prostate IMRT treatment plans are compared. Results show that the plan with the highest TCI+ values accomplished the competing goals of tumor coverage and critical structures sparing best, among rival treatment plans for both treatment sites. The study demonstrates, first, that dose-volume-based indices, which summarize complex dose distributions through a single index, can be used to automatically select the optimal plan among competing plans, and second, that this dose-volume-based index may be appropriate for ranking IMRT dose distributions.

  20. Reliability of dose volume constraint inference from clinical data

    DEFF Research Database (Denmark)

    Lutz, C M; Møller, D S; Hoffmann, L

    2017-01-01

    Dose volume histogram points (DVHPs) frequently serve as dose constraints in radiotherapy treatment planning. An experiment was designed to investigate the reliability of DVHP inference from clinical data for multiple cohort sizes and complication incidence rates. The experimental background...... was radiation pneumonitis in non-small cell lung cancer and the DVHP inference method was based on logistic regression. From 102 NSCLC real-life dose distributions and a postulated DVHP model, an 'ideal' cohort was generated where the most predictive model was equal to the postulated model. A bootstrap...... and a Cohort Replication Monte Carlo (CoRepMC) approach were applied to create 1000 equally sized populations each. The cohorts were then analyzed to establish inference frequency distributions. This was applied to nine scenarios for cohort sizes of 102 (1), 500 (2) to 2000 (3) patients (by sampling...

  1. Hyperglycemia in critical patients: Determinants of insulin dose choice

    Directory of Open Access Journals (Sweden)

    Aline Klitzke Paliosa

    Full Text Available Summary Objective: To identify factors that can determine the choice of intermittent subcutaneous regular insulin dose in critically ill patients with hyperglycemia. Method: Cross-sectional study in a general adult ICU with 26 beds, data collected between September and October 2014. The variables analyzed were: sex, age, previous diagnosis of diabetes mellitus, use of corticosteroids, use of lactulose, sepsis, fasting, enteral nutrition, use of dextrose 5% in water, NPH insulin prescription and blood glucose level. Patients with one or more episodes of hyperglycemia (blood glucose greater than 180 mg/dL were included as a convenience sample, not consecutively. Those with continuous insulin prescription were excluded from analysis. Results: We included 64 records of hyperglycemia observed in 22 patients who had at least one episode of hyperglycemia. The median administered subcutaneous regular human insulin was 6 IU and among the factors evaluated only blood glucose levels were associated with the choice of insulin dose administered. Conclusion: Clinical characteristics such as diet, medications and diagnosis of diabetes mellitus are clearly ignored in the decision-making regarding insulin dose to be administered for glucose control in critically ill patients with hyperglycemia.

  2. Comparison of dose length, area, and volume histograms as quantifiers of urethral dose in prostate brachytherapy

    International Nuclear Information System (INIS)

    Butler, Wayne M.; Merrick, Gregory S.; Dorsey, Anthony T.; Hagedorn, Brenda M.

    2000-01-01

    Purpose: To determine the magnitude of the differences between urethral dose-volume, dose-area, and dose-length histograms (DVH, DAH, and DLH, respectively, or DgH generically). Methods and Materials: Six consecutive iodine-125 ( 125 I) patients and 6 consecutive palladium-103 ( 103 Pd) patients implanted via a modified uniform planning approach were evaluated with day 0 computed tomography (CT)-based dosimetry. The urethra was identified by the presence of a urinary catheter and was hand drawn on the CT images with a mean radius of 3.3 ± 0.7 mm. A 0.1-mm calculation matrix was employed for the urethral volume and surface analysis, and urethral dose points were placed at the centroid of the urethra on each 5-mm CT slice. Results: Although individual patient DLHs were step-like, due to the sparseness of the data points, the composite urethral DLH, DAH, and DVHs were qualitatively similar. The DAH curve delivered more radiation than the other two curves at all doses greater than 90% of the prescribed minimum peripheral dose (mPD) to the prostate. In addition, the DVH curve was consistently higher than the DLH curve at most points throughout that range. Differences between the DgH curves were analyzed by integrating the difference curves between 0 and 200% of the mPD. The area-length, area-volume, and volume-length difference curves integrated in the ratio of 3:2:1. The differences were most pronounced near the inflection point of the DgH curves with mean A 125 , V 125 , and L 125 values of 36.6%, 31.4%, and 23.0%, respectively, of the urethra. Quantifiers of urethral hot spots such as D 10 , defined as the minimal dose delivered to the hottest 10% of the urethra, followed the same ranking: area analysis indicated the highest dose and length analysis, the lowest dose. D 10 was 148% and 136% of mPD for area and length evaluations, respectively. Comparing the two isotopes in terms of the amount of urethra receiving a given dose, 103 Pd implants were significantly

  3. Genistein genotoxicity: Critical considerations of in vitro exposure dose

    International Nuclear Information System (INIS)

    Klein, Catherine B.; King, Audrey A.

    2007-01-01

    The potential health benefits of soy-derived phytoestrogens include their reported utility as anticarcinogens, cardioprotectants and as hormone replacement alternatives in menopause. Although there is increasing popularity of dietary phytoestrogen supplementation and of vegetarian and vegan diets among adolescents and adults, concerns about potential detrimental or other genotoxic effects persist. While a variety of genotoxic effects of phytoestrogens have been reported in vitro, the concentrations at which such effects occurred were often much higher than the physiologically relevant doses achievable by dietary or pharmacologic intake of soy foods or supplements. This review focuses on in vitro studies of the most abundant soy phytoestrogen, genistein, critically examining dose as a crucial determinant of cellular effects. In consideration of levels of dietary genistein uptake and bioavailability we have defined in vitro concentrations of genistein > 5 μM as non-physiological, and thus 'high' doses, in contrast to much of the previous literature. In doing so, many of the often-cited genotoxic effects of genistein, including apoptosis, cell growth inhibition, topoisomerase inhibition and others become less obvious. Recent cellular, epigenetic and microarray studies are beginning to decipher genistein effects that occur at dietarily relevant low concentrations. In toxicology, the well accepted principle of 'the dose defines the poison' applies to many toxicants and can be invoked, as herein, to distinguish genotoxic versus potentially beneficial in vitro effects of natural dietary products such as genistein

  4. Breckinridge Project, initial effort. Report XI, Volume V. Critical review of the design basis. [Critical review

    Energy Technology Data Exchange (ETDEWEB)

    None

    1982-01-01

    Report XI, Technical Audit, is a compendium of research material used during the Initial Effort in making engineering comparisons and decisions. Volumes 4 and 5 of Report XI present those studies which provide a Critical Review of the Design Basis. The Critical Review Report, prepared by Intercontinental Econergy Associates, Inc., summarizes findings from an extensive review of the data base for the H-Coal process design. Volume 4 presents this review and assessment, and includes supporting material; specifically, Design Data Tabulation (Appendix A), Process Flow Sheets (Appendix B), and References (Appendix C). Volume 5 is a continuation of the references of Appendix C. Studies of a proprietary nature are noted and referenced, but are not included in these volumes. They are included in the Limited Access versions of these reports and may be reviewed by properly cleared personnel in the offices of Ashland Synthetic Fuels, Inc.

  5. Breckinridge Project, initial effort. Report XI, Volume IV. Critical review of the design basis. [Critical review

    Energy Technology Data Exchange (ETDEWEB)

    None

    1981-05-01

    Report XI, Technical Audit, is a compendium of research material used during the Initial Effort in making engineering comparisons and decisions. Volumes 4 and 5 of Report XI present those studies which provide a Critical Review of the Design Basis. The Critical Review Report, prepared by Intercontinental Econergy Associates, Inc., summarizes findings from an extensive review of the data base for the H-Coal process design. Volume 4 presents this review and assessment, and includes supporting material; specifically, Design Data Tabulation (Appendix A), Process Flow Sheets (Appendix B), and References (Appendix C). Volume 5 is a continuation of the references of Appendix C. Studies of a proprietary nature are noted and referenced, but are not included in these volumes. They are included in the Limited Access versions of these reports and may be reviewed by properly cleared personnel in the offices of Ashland Synthetic Fuels, Inc.

  6. TL detectors for gamma ray dose measurements in criticality accidents.

    Science.gov (United States)

    Miljanić, Saveta; Zorko, Benjamin; Gregori, Beatriz; Knezević, Zeljka

    2007-01-01

    Determination of gamma ray dose in mixed neutron+gamma ray fields is still a demanding task. Dosemeters used for gamma ray dosimetry are usually in some extent sensitive to neutrons and their response variations depend on neutron energy i.e., on neutron spectra. Besides, it is necessary to take into account the energy dependence of dosemeter responses to gamma rays. In this work, several types of thermoluminescent detectors (TLD) placed in different holders used for gamma ray dose determination in the mixed fields were examined. Dosemeters were from three different institutions: Ruder Bosković Institute (RBI), Croatia, JoZef Stefan Institute (JSI), Slovenia and Autoridad Regulatoria Nuclear (ARN), Argentina. All dosemeters were irradiated during the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002. Three accidental scenarios were reproduced and in each irradiation the dosemeters were exposed placed on the front of phantom and 'free in air'. Following types of TLDs were used: 7LiF (TLD-700), CaF2:Mn and Al2O3:Mg,Y-all from RBI; CaF2:Mn from JSI and 7LiF (TLD-700) from ARN. Reported doses were compared with the reference values as well as with the values obtained from the results of all participants. The results show satisfactory agreement with other dosimetry systems used in the Intercomparison. The influence of different types of holders and applied corrections of dosemeters' readings are discussed.

  7. Evaluation of a standard breast tangent technique: a dose-volume analysis of tangential irradiation using three-dimensional tools

    International Nuclear Information System (INIS)

    Krasin, Matthew; McCall, Anne; King, Stephanie; Olson, Mary; Emami, Bahman

    2000-01-01

    Purpose: A thorough dose-volume analysis of a standard tangential radiation technique has not been published. We evaluated the adequacy of a tangential radiation technique in delivering dose to the breast and regional lymphatics, as well as dose delivered to underlying critical structures. Methods and Materials: Treatment plans of 25 consecutive women with breast cancer undergoing lumpectomy and adjuvant breast radiotherapy were studied. Patients underwent two-dimensional (2D) treatment planning followed by treatment with standard breast tangents. These 2D plans were reconstructed without modification on our three-dimensional treatment planning system and analyzed with regard to dose-volume parameters. Results: Adequate coverage of the breast (defined as 95% of the target receiving at least 95% of the prescribed dose) was achieved in 16 of 25 patients, with all patients having at least 85% of the breast volume treated to 95% of the prescribed dose. Only 1 patient (4%) had adequate coverage of the Level I axilla, and no patient had adequate coverage of the Level II axilla, Level III axilla, or the internal mammary lymph nodes. Conclusion: Three-dimensional treatment planning is superior in quantification of the dose received by the breast, regional lymphatics, and critical structures. The standard breast tangent technique delivers an adequate dose to the breast but does not therapeutically treat the regional lymph nodes in the majority of patients. If coverage of the axilla or internal mammary lymph nodes is desired, alternate beam arrangements or treatment fields will be necessary

  8. Reliability of dose volume constraint inference from clinical data

    Science.gov (United States)

    Lutz, C. M.; Møller, D. S.; Hoffmann, L.; Knap, M. M.; Alber, M.

    2017-04-01

    Dose volume histogram points (DVHPs) frequently serve as dose constraints in radiotherapy treatment planning. An experiment was designed to investigate the reliability of DVHP inference from clinical data for multiple cohort sizes and complication incidence rates. The experimental background was radiation pneumonitis in non-small cell lung cancer and the DVHP inference method was based on logistic regression. From 102 NSCLC real-life dose distributions and a postulated DVHP model, an ‘ideal’ cohort was generated where the most predictive model was equal to the postulated model. A bootstrap and a Cohort Replication Monte Carlo (CoRepMC) approach were applied to create 1000 equally sized populations each. The cohorts were then analyzed to establish inference frequency distributions. This was applied to nine scenarios for cohort sizes of 102 (1), 500 (2) to 2000 (3) patients (by sampling with replacement) and three postulated DVHP models. The Bootstrap was repeated for a ‘non-ideal’ cohort, where the most predictive model did not coincide with the postulated model. The Bootstrap produced chaotic results for all models of cohort size 1 for both the ideal and non-ideal cohorts. For cohort size 2 and 3, the distributions for all populations were more concentrated around the postulated DVHP. For the CoRepMC, the inference frequency increased with cohort size and incidence rate. Correct inference rates  >85 % were only achieved by cohorts with more than 500 patients. Both Bootstrap and CoRepMC indicate that inference of the correct or approximate DVHP for typical cohort sizes is highly uncertain. CoRepMC results were less spurious than Bootstrap results, demonstrating the large influence that randomness in dose-response has on the statistical analysis.

  9. Target volume uncertainty and a method to visualize its effect on the target dose prescription

    International Nuclear Information System (INIS)

    McCormick, Traci; Dink, Delal; Orcun, Seza; Pekny, Joseph; Rardin, Ron; Baxter, Larry; Thai, Van; Langer, Mark

    2004-01-01

    Purpose: To consider the uncertainty in the construction of target boundaries for optimization, and to demonstrate how the principles of mathematical programming can be applied to determine and display the effect on the tumor dose of making small changes to the target boundary. Methods: The effect on the achievable target dose of making successive small shifts to the target boundary within its range of uncertainty was found by constructing a mixed-integer linear program that automated the placement of the beam angles using the initial target volume. Results: The method was demonstrated using contours taken from a nasopharynx case, with dose limits placed on surrounding structures. In the illustrated case, enlarging the target anteriorly to provide greater assurance of disease coverage did not force a sacrifice in the minimum or mean tumor doses. However, enlarging the margin posteriorly, near a critical structure, dramatically changed the minimum, mean, and maximum tumor doses. Conclusion: Tradeoffs between the position of the target boundary and the minimum target dose can be developed using mixed-integer programming, and the results projected as a guide to contouring and plan selection

  10. Comments on 'Reconsidering the definition of a dose-volume histogram'--dose-mass histogram (DMH) versus dose-volume histogram (DVH) for predicting radiation-induced pneumonitis.

    Science.gov (United States)

    Mavroidis, Panayiotis; Plataniotis, Georgios A; Górka, Magdalena Adamus; Lind, Bengt K

    2006-12-21

    In a recently published paper (Nioutsikou et al 2005 Phys. Med. Biol. 50 L17) the authors showed that the use of the dose-mass histogram (DMH) concept is a more accurate descriptor of the dose delivered to lung than the traditionally used dose-volume histogram (DVH) concept. Furthermore, they state that if a functional imaging modality could also be registered to the anatomical imaging modality providing a functional weighting across the organ (functional mass) then the more general and realistic concept of the dose-functioning mass histogram (D[F]MH) could be an even more appropriate descriptor. The comments of the present letter to the editor are in line with the basic arguments of that work since their general conclusions appear to be supported by the comparison of the DMH and DVH concepts using radiobiological measures. In this study, it is examined whether the dose-mass histogram (DMH) concept deviated significantly from the widely used dose-volume histogram (DVH) concept regarding the expected lung complications and if there are clinical indications supporting these results. The problem was investigated theoretically by applying two hypothetical dose distributions (Gaussian and semi-Gaussian shaped) on two lungs of uniform and varying densities. The influence of the deviation between DVHs and DMHs on the treatment outcome was estimated by using the relative seriality and LKB models using the Gagliardi et al (2000 Int. J. Radiat. Oncol. Biol. Phys. 46 373) and Seppenwoolde et al (2003 Int. J. Radiat. Oncol. Biol. Phys. 55 724) parameter sets for radiation pneumonitis, respectively. Furthermore, the biological equivalent of their difference was estimated by the biologically effective uniform dose (D) and equivalent uniform dose (EUD) concepts, respectively. It is shown that the relation between the DVHs and DMHs varies depending on the underlying cell density distribution and the applied dose distribution. However, the range of their deviation in terms of the

  11. Oxymetazoline Metered Dose Spray: Factors Affecting Delivery Volume.

    Science.gov (United States)

    Hakim, Mumin; Walia, Hina; Rafiq, Mahmood; Grannell, Timothy; Cartabuke, Richard S; Tobias, Joseph D

    2016-01-01

    The current study compared the amount of oxymetazoline delivered by various anesthesia providers when holding the bottle in the upright and inverted position. Additionally, the amount delivered from a full bottle and a half-full bottle was also investigated. Using an analytical balance that was calibrated to zero, we evaluated the impact the position of the bottle and the volume of oxymetazoline in the bottle had on the amount being delivered by both anesthesia staff and trainees. When using both filled and half-filled bottles, the amount delivered increased significantly when comparing the upright versus inverted position. With a full bottle, the amount delivered when the bottle was inverted increased almost 10-fold from 62 ± 80 to 606 ± 366 μL (p oxymetazoline delivered for metered dose bottles. Given the potential for severe end-organ effects with excessive dosage, alternative means of delivery are needed for its perioperative use.

  12. Dose-volume objectives in multi-criteria optimization

    Energy Technology Data Exchange (ETDEWEB)

    Halabi, Tarek; Craft, David; Bortfeld, Thomas [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114 (United States)

    2006-08-07

    Unlike conventional optimization with dose-volume (DV) constraints, multi-criteria optimization (MCO) with DV objectives provides tradeoff information which we believe is necessary for choosing better treatment plans. We show that the MCO formulation with DV objectives is better suited to convex approximation than conventional formulations with DV constraints. We provide a relaxation of the integer programming formulation which reduces the computation time for a single plan from over 5 h to about 2 min, without significantly compromising the results. We also derive a heuristic to improve on the relaxed solutions, adding only a few additional minutes of computation time. We apply these techniques to a skull based tumour case and a paraspinal tumour case. Based on a careful examination of the driving terms in the relaxed formulation and the heuristic, we argue that our techniques should apply more generally for DV objectives in multi-objective IMRT treatment planning.

  13. Dose-volume effects in rat thoracolumbar spinal cord: an evaluation of NTCP models.

    Science.gov (United States)

    Philippens, Marielle E P; Pop, Lucas A M; Visser, Andries G; Schellekens, Suzanne A M W; van der Kogel, Albert J

    2004-10-01

    To evaluate models for normal-tissue-complication probability (NTCP) on describing the dose-volume effect in rat thoracolumbar spinal cord. Single-dose irradiation of four field lengths (4, 1.5, 1.0, and 0.5 cm) was evaluated by the endpoints paresis and white-matter necrosis. The resulting dose-response data were used to rank phenomenological and tissue architecture NTCP models. The 0.5-cm field length showed a steep increase in radiation tolerance. Statistical analysis of the model fits, which included evaluation of goodness of fit (GOF) and confidence intervals, resulted in the rejection of all the models considered. Excluding the smallest field length, the Schultheiss (D(50) = 21.5 Gy, k = 26.5), the relative seriality (D(50) = 21.4 Gy, s = 1.6, gamma(50) = 6.3), and the critical element (D(50,FSU) = 26.6 Gy, gamma(50,FSU) = 2.3, n = 1.3) model gave the best fit. A thorough statistical analysis resulted in a serial or critical-element behavior for the field lengths of 1.0 cm and greater. Including the 0.5-cm field length, the radiation response markedly diverged from serial properties, but none of the models applied acceptably described this dose-response relationship. This study suggests that the commonly assumed serial behavior of the spinal cord might be valid for daily use in external- beam irradiation.

  14. Conformal irradiation of the prostate: estimating long-term rectal bleeding risk using dose-volume histograms

    International Nuclear Information System (INIS)

    Hartford, Alan C.; Niemierko, Andrzej; Adams, Judith A.; Urie, Marcia M.; Shipley, William U.

    1996-01-01

    Purpose: Dose-volume histograms (DVHs) may be very useful tools for estimating probability of normal tissue complications (NTCP), but there is not yet an agreed upon method for their analysis. This study introduces a statistical method of aggregating and analyzing primary data from DVHs and associated outcomes. It explores the dose-volume relationship for NTCP of the rectum, using long-term data on rectal wall bleeding following prostatic irradiation. Methods and Materials: Previously published data were reviewed and updated on 41 patients with Stages T3 and T4 prostatic carcinoma treated with photons followed by perineal proton boost, including dose-volume histograms (DVHs) of each patient's anterior rectal wall and data on the occurrence of postirradiation rectal bleeding (minimum FU > 4 years). Logistic regression was used to test whether some individual combination of dose and volume irradiated might best separate the DVHs into categories of high or low risk for rectal bleeding. Further analysis explored whether a group of such dose-volume combinations might be superior in predicting complication risk. These results were compared with results of the 'critical volume model', a mathematical model based on assumptions of underlying radiobiological interactions. Results: Ten of the 128 tested dose-volume combinations proved to be 'statistically significant combinations' (SSCs) distinguishing between bleeders (14 out of 41) and nonbleeders (27 out of 41), ranging contiguously between 60 CGE (Cobalt Gray Equivalent) to 70% of the anterior rectal wall and 75 CGE to 30%. Calculated odds ratios for each SSC were not significantly different across the individual SSCs; however, analysis combining SSCs allowed segregation of DVHs into three risk groups: low, moderate, and high. Estimates of probabilities of normal tissue complications (NTCPs) based on these risk groups correlated strongly with observed data (p = 0.003) and with biomathematical model-generated NTCPs

  15. Elucidating the role of dose in the biopharmaceutics classification of drugs: the concepts of critical dose, effective in vivo solubility, and dose-dependent BCS.

    Science.gov (United States)

    Charkoftaki, Georgia; Dokoumetzidis, Aristides; Valsami, Georgia; Macheras, Panos

    2012-11-01

    To develop a dose dependent version of BCS and identify a critical dose after which the amount absorbed is independent from the dose. We utilized a mathematical model of drug absorption in order to produce simulations of the fraction of dose absorbed (F) and the amount absorbed as function of the dose for the various classes of BCS and the marginal cases in between classes. Simulations based on the mathematical model of F versus dose produced patterns of a constant F throughout a wide range of doses for drugs of Classes I, II and III, justifying biowaiver claim. For Classes I and III the pattern of a constant F stops at a critical dose Dose(cr) after which the amount of drug absorbed, is independent from the dose. For doses higher than Dose(cr), Class I drugs become Class II and Class III drugs become Class IV. Dose(cr) was used to define an in vivo effective solubility as S(eff) = Dose(cr)/250 ml. Literature data were used to support our simulation results. A new biopharmaceutic classification of drugs is proposed, based on F, separating drugs into three regions, taking into account the dose, and Dose(cr), while the regions for claiming biowaiver are clearly defined.

  16. Dose-volume effects in the rat cervical spinal cord after proton irradiation

    International Nuclear Information System (INIS)

    Bijl, Hendrik P.; Vuijk, Peter van; Coppes, Rob P.; Schippers, Jacobus M.; Konings, Antonius W.T.; Kogel, Albert J. van der

    2002-01-01

    Purpose: To estimate dose-volume effects in the rat cervical spinal cord with protons. Methods and Materials: Wistar rats were irradiated on the cervical spinal cord with a single fraction of unmodulated protons (150-190 MeV) using the shoot through method, which employs the plateau of the depth-dose profile rather than the Bragg peak. Four different lengths of the spinal cord (2, 4, 8, and 20 mm) were irradiated with variable doses. The endpoint for estimating dose-volume effects was paralysis of fore or hind limbs. Results: The results obtained with a high-precision proton beam showed a marginal increase of ED 50 when decreasing the irradiated cord length from 20 mm (ED 50 = 20.4 Gy) to 8 mm (ED 50 = 24.9 Gy), but a steep increase in ED 50 when further decreasing the length to 4 mm (ED 50 = 53.7 Gy) and 2 mm (ED 50 = 87.8 Gy). These results generally confirm data obtained previously in a limited series with 4-6-MV photons, and for the first time it was possible to construct complete dose-response curves down to lengths of 2 mm. At higher ED 50 values and shorter lengths irradiated, the latent period to paralysis decreased from 125 to 60 days. Conclusions: Irradiation of variable lengths of rat cervical spinal cord with protons showed steeply increasing ED 50 values for lengths of less than 8 mm. These results suggest the presence of a critical migration distance of 2-3 mm for cells involved in regeneration processes

  17. Decreasing Irradiated Rat Lung Volume Changes Dose-Limiting Toxicity From Early to Late Effects

    International Nuclear Information System (INIS)

    Veen, Sonja J. van der; Faber, Hette; Ghobadi, Ghazaleh; Brandenburg, Sytze; Langendijk, Johannes A.; Coppes, Robert P.; Luijk, Peter van

    2016-01-01

    Purpose: Technological developments in radiation therapy result in smaller irradiated volumes of normal tissue. Because the risk of radiation therapy-induced toxicity generally depends on irradiated volume, changing volume could change the dose-limiting toxicity of a treatment. Recently, in our rat model, we found that early radiation-induced lung dysfunction (RILD) was closely related to irradiated volume dependent vascular remodeling besides inflammation. The exact relationship between early and late RILD is still unknown. Therefore, in this preclinical study we investigated the dose-volume relationship of late RILD, assessed its dependence on early and late pathologies and studied if decreasing irradiated volume changed the dose-limiting toxicity. Methods and Materials: A volume of 25%, 32%, 50%, 63%, 88%, or 100% of the rat lung was irradiated using protons. Until 26 weeks after irradiation, respiratory rates were measured. Macrovascular remodeling, pulmonary inflammation, and fibrosis were assessed at 26 weeks after irradiation. For all endpoints dose-volume response curves were made. These results were compared to our previously published early lung effects. Results: Early vascular remodeling and inflammation correlated significantly with early RILD. Late RILD correlated with inflammation and fibrosis, but not with vascular remodeling. In contrast to the early effects, late vascular remodeling, inflammation and fibrosis showed a primarily dose but not volume dependence. Comparison of respiratory rate increases early and late after irradiation for the different dose-distributions indicated that with decreasing irradiated volumes, the dose-limiting toxicity changed from early to late RILD. Conclusions: In our rat model, different pathologies underlie early and late RILD with different dose-volume dependencies. Consequently, the dose-limiting toxicity changed from early to late dysfunction when the irradiated volume was reduced. In patients, early and late

  18. Dose-volume histograms associated to long-term colorectal functions in patients receiving pelvic radiotherapy

    International Nuclear Information System (INIS)

    Fokdal, Lars; Honore, Henriette; Hoyer, Morten; Maase, Hans von der

    2005-01-01

    Background and purpose: To correlate long-term colorectal dysfunctions following radical radiotherapy for bladder or prostate cancer with clinical parameters and dose-volume histogram parameters of the small intestine, rectum, and anal canal volume. Materials and methods: Seventy-one patients previously treated for bladder or prostate cancer were interviewed following CT-based radiotherapy of 60-70 Gy with questions concerning long-term colorectal dysfunctions. Median follow-up time was 30 months (range 12-109 months). Clinical parameters and parameters from the dose-volume histograms were correlated with colorectal dysfunctions (Spearman's test). Median and quartile values of all parameters were used as cut-off values for statistical analyses. A logistic regression model was used for analysis of urgency and incontinence in relation to median or maximum radiation dose to the anal canal volume. Results: Rectum length, volume and several dose-volume parameters from the anal canal volume and rectal volume were correlated with late organ dysfunctions. In a logistic model, fecal urgency and incontinence were dependent of dose-volume parameters from the anal canal volume. No relation between age or follow-up time and late effects were found. Dose-volume parameters of the small intestine were not related to any late dysfunctions. Conclusions: A relationship between several late anorectal dysfunctions and dose-volume parameters from the rectum and anal canal volume was demonstrated. It is recommended to exclude the anal canal volume from the high dose-volume and to apply rectal shielding whenever possible to prevent late anorectal dysfunctions

  19. Volumes and doses for external radiotherapy - Definitions and recommendations; Volum og doser i ekstern straaleterapi - Definisjoner og anbefalinger

    Energy Technology Data Exchange (ETDEWEB)

    Levernes, Sverre (ed.)

    2012-07-01

    The report contains definitions of volume and dose parameters for external radiotherapy. In addition the report contains recommendations for use, documentation and minimum reporting for radiotherapy of the individual patient.(Author)

  20. SU-F-19A-03: Dosimetric Advantages in Critical Structure Dose Sparing by Using a Multichannel Cylinder in High Dose Rate Brachytherapy to Treat Vaginal Cuff Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Syh, J; Syh, J; Patel, B; Zhang, J; Wu, H; Rosen, L [Willis-Knighton Cancer Center, Shreveport, LA (United States)

    2014-06-15

    Purpose: The multichannel cylindrical vaginal applicator is a variation of traditional single channel cylindrical vaginal applicator. The multichannel applicator has additional peripheral channels that provide more flexibility in the planning process. The dosimetric advantage is to reduce dose to adjacent organ at risk (OAR) such as bladder and rectum while maintaining target coverage with the dose optimization from additional channels. Methods: Vaginal HDR brachytherapy plans are all CT based. CT images were acquired in 2 mm thickness to keep integrity of cylinder contouring. The CTV of 5mm Rind with prescribed treatment length was reconstructed from 5mm expansion of inserted cylinder. The goal was 95% of CTV covered by 95% of prescribed dose in both single channel planning (SCP)and multichannel planning (MCP) before proceeding any further optimization for dose reduction to critical structures with emphasis on D2cc and V2Gy . Results: This study demonstrated noticeable dose reduction to OAR was apparent in multichannel plans. The D2cc of the rectum and bladder were showing the reduced dose for multichannel versus single channel. The V2Gy of the rectum was 93.72% and 83.79% (p=0.007) for single channel and multichannel respectively (Figure 1 and Table 1). To assure adequate coverage to target while reducing the dose to the OAR without any compromise is the main goal in using multichannel vaginal applicator in HDR brachytherapy. Conclusion: Multichannel plans were optimized using anatomical based inverse optimization algorithm of inverse planning simulation annealing. The optimization solution of the algorithm was to improve the clinical target volume dose coverage while reducing the dose to critical organs such as bladder, rectum and bowels. The comparison between SCP and MCP demonstrated MCP is superior to SCP where the dwell positions were based on geometric array only. It concluded that MCP is preferable and is able to provide certain features superior to SCP.

  1. The Impact of Heart Irradiation on Dose-Volume Effects in the Rat Lung

    International Nuclear Information System (INIS)

    Luijk, Peter van; Faber, Hette; Meertens, Harm; Schippers, Jacobus M.; Langendijk, Johannes A.; Brandenburg, Sytze; Kampinga, Harm H.; Coppes, Robert P. Ph.D.

    2007-01-01

    Purpose: To test the hypothesis that heart irradiation increases the risk of a symptomatic radiation-induced loss of lung function (SRILF) and that this can be well-described as a modulation of the functional reserve of the lung. Methods and Materials: Rats were irradiated with 150-MeV protons. Dose-response curves were obtained for a significant increase in breathing frequency after irradiation of 100%, 75%, 50%, or 25% of the total lung volume, either including or excluding the heart from the irradiation field. A significant increase in the mean respiratory rate after 6-12 weeks compared with 0-4 weeks was defined as SRILF, based on biweekly measurements of the respiratory rate. The critical volume (CV) model was used to describe the risk of SRILF. Fits were done using a maximum likelihood method. Consistency between model and data was tested using a previously developed goodness-of-fit test. Results: The CV model could be fitted consistently to the data for lung irradiation only. However, this fitted model failed to predict the data that also included heart irradiation. Even refitting the model to all data resulted in a significant difference between model and data. These results imply that, although the CV model describes the risk of SRILF when the heart is spared, the model needs to be modified to account for the impact of dose to the heart on the risk of SRILF. Finally, a modified CV model is described that is consistent to all data. Conclusions: The detrimental effect of dose to the heart on the incidence of SRILF can be described by a dose dependent decrease in functional reserve of the lung

  2. Impact of electromechanical parameter variations in treatment volume doses and adjacent structures; Impacto da variacao dos parametros eletro-mecanicos nas doses do volume de tratamento e nas estruturas adjacentes

    Energy Technology Data Exchange (ETDEWEB)

    Morais, M.E.; Campos, A.M. [Instituto Nacional do Cancer (INCa), Rio de Janeiro, RJ (Brazil). Programa de Qualidade em Radioterapia]. E-mails: memorais@yahoo.com.br; amcampos@inca.gov.br; Goncalves, J. F. [Instituto de Oncologia e Radioterapia GV, Governador Valadares, MG (Brazil)]. E-mail: joelfgoncalves@yahoo.com.br; Ferreira, M.L. [Centro Radioterapico Gavea, Rio de Janeiro, RJ (Brazil)]. E-mail: mluciaf@yahoo.com

    2003-07-01

    ICRU Report 62 recommends that radiotherapy treatment dose should be prescribed in such a way that the dose to the target volume varies no more than 10%. In order to keep this goal, a very important role is played by the quality assurance (QA) of the treatment unit associated to the high level work of the personnel involved in planning and patient treatment. This paper shows the influence of the main electrical and mechanical linear accelerator parameters: field size, source-skin distance, gantry angle and light x radiation field coincidence in tumor volume and adjacent organ doses. We simulated a cubic tumor and a cubic adjacent critical organ in a cubic phantom and used a 3D Prowess system for planning. The treatment has been simulated for a 6 MV linear accelerator. We simulated two treatment planning: one using all the parameters inside their tolerance limits and another doubling these limits. The final results have show that, if the irradiation machine operates out of the tolerance limits, the dose variation in the planning target volume (PTV) can goes till {+-} 5,8% and in the critical adjacent organ till {+-} 7,7%. Therefore we concluded that, according to the complexity of the treatment, it can be necessary to reduce the tolerance levels advised by the IAEA/TECDOC - 1151. (author)

  3. Radiation tolerance of the cervical spinal cord: incidence and dose-volume relationship of symptomatic and asymptomatic late effects following high dose irradiation of paraspinal tumors

    International Nuclear Information System (INIS)

    Liu, Mitchell C.C.; Munzenrider, John E.; Finkelstein, Dianne; Liebsch, Norbert; Adams, Judy; Hug, Eugen B.

    1997-01-01

    Purpose: Low grade chordomas and chondrosarcomas require high radiation doses for effective, lasting tumor control. Fractionated, 3-D planned, conformal proton radiation therapy has been used for lesions along the base of skull and spine to deliver high target doses, while respecting constraints of critical, normal tissues. In this study, we sought to determine the incidence of myelopathy after high dose radiotherapy to the cervical spine and investigated the influence of various treatment parameters, including dose-volume relationship. Methods and Materials: Between December 1980 and March 1996, 78 patients were treated at the Massachusetts General Hospital and Harvard Cyclotron Laboratory for primary or recurrent chordomas and chondrosarcomas of the cervical spine using combined proton and photon radiation therapy. In general, the tumor dose given was between 64.5 to 79.2 CGE (Cobalt Gray Equivalent). The guidelines for maximum permissible doses to spinal cord were: ≤ 64 CGE to the spinal cord surface and ≤ 53 CGE to the spinal cord center. Dose volume histograms of the spinal cord were analyzed to investigate a possible dose and volume relationship. Results: With a mean follow-up period of 46.6 months (range: 3 - 157 months), 4 of 78 patients (5.1%) developed high-grade (RTOG Grade 3 and 4) late toxicity: 3 patients (3.8%) experienced sensory deficits without motor deficits, none had any limitations of daily activities. One patient (1.2%) developed motor deficit with loss of motor function of one upper extremity. The only patient, who developed permanent motor damage had received additional prior radiation treatment and therefore received a cumulative spinal cord dose higher than the treatment guidelines. No patient treated within the guidelines experienced any motor impairment. Six patients (7.7%) experienced transient Lhermitt's syndrome and 1 patient (1.2%) developed asymptomatic radiographic MR findings only. Time to onset of symptoms of radiographic

  4. Estimation of dose in dental radiology exams in critical regions

    International Nuclear Information System (INIS)

    Bonzoumet, S.P.J.; Braz, D.; Padilha, Lucas

    2005-01-01

    The objective of this paper is to estimate the values of doses, which are absorbed dose to the lens and thyroid in a dental X-ray. Thermoluminescence dosimeters were used, once they provide a reading of quality and effectiveness. This study was based on dental exams conducted in patients in order to estimate the dose that disperses to the lens of the eye and for the thyroid during an intraoral exam. Data collection took place in two institutions, one governmental, which had the device SELETRONIC 70X and other particular. This study showed that there is a considerable variation between the appliances. Using the appliance DABI 1070, there was a greater absorption of radiation in the right eye (values greater than 5 mGy) and a lower dose in the thyroid, and the Seletronic 70X presented an incidence of higher dose deposited in the skin and in other points there was a balance in the values. In the appliance SELETRONIC 70X, there was again a greater absorption of radiation in the right eye and a lower setting in the thyroid. The excessive dose, besides does not favor at all for the quality of radiograph, represents a risk for the patient who absorbs unnecessary and harmful radiation to the body

  5. The role and strategy of IMRT in radiotherapy of pelvic tumors: Dose escalation and critical organ sparing in prostate cancer

    International Nuclear Information System (INIS)

    Liu, Y.-M.; Shiau, C.-Y.; Lee, M.-L.; Huang, P.-I.; Hsieh, C.-M.; Chen, P.-H.; Lin, Y.-H.; Wang, L.-W.; Yen, S.-H.

    2007-01-01

    Purpose: To investigate the intensity-modulated radiotherapy (IMRT) strategy in dose escalation of prostate and pelvic lymph nodes. Methods and Materials: Plan dosimetric data of 10 prostate cancer patients were compared with two-dimensional (2D) or IMRT techniques for pelvis (two-dimensional whole pelvic radiation therapy [2D-WPRT] or IM-WPRT) to receive 50 Gy or 54 Gy and additional prostate boost by three-dimensional conformal radiation therapy or IMRT (3D-PBRT or IM-PBRT) techniques up to 72 Gy or 78 Gy. Dose-volume histograms (DVHs), normal tissue complication probabilities (NTCP) of critical organ, and conformity of target volume in various combinations were calculated. Results: In DVH analysis, the plans with IM-WPRT (54 Gy) and additional boost up to 78 Gy had lower rectal and bladder volume percentage at 50 Gy and 60 Gy, compared with those with 2D-WPRT (50 Gy) and additional boost up to 72 Gy or 78 Gy. Those with IM-WPRT (54 Gy) also had better small bowel sparing at 30 Gy and 50 Gy, compared with those with 2D-WPRT (50 Gy). In NTCP, those with IM-WPRT and total dose of 78 Gy achieved lower complication rates in rectum and small bowel, compared with those of 2D-WPRT with total dose of 72 Gy. In conformity, those with IM-WPRT had better conformity compared with those with 2D-WPRT with significance (p < 0.005). No significant difference in DVHs, NTCP, or conformity was found between IM-PBRT and 3D-PBRT after IM-WPRT. Conclusions: Initial pelvic IMRT is the most important strategy in dose escalation and critical organ sparing. IM-WPRT is recommended for patients requiring WPRT. There is not much benefit for critical organ sparing by IMRT after 2D-WPRT

  6. Mesorad dose assessment model. Volume 1. Technical basis

    International Nuclear Information System (INIS)

    Scherpelz, R.I.; Bander, T.J.; Athey, G.F.; Ramsdell, J.V.

    1986-03-01

    MESORAD is a dose assessment model for emergency response applications. Using release data for as many as 50 radionuclides, the model calculates: (1) external doses resulting from exposure to radiation emitted by radionuclides contained in elevated or deposited material; (2) internal dose commitment resulting from inhalation; and (3) total whole-body doses. External doses from airborne material are calculated using semi-infinite and finite cloud approximations. At each stage in model execution, the appropriate approximation is selected after considering the cloud dimensions. Atmospheric processes are represented in MESORAD by a combination of Lagrangian puff and Gaussian plume dispersion models, a source depletion (deposition velocity) dry deposition model, and a wet deposition model using washout coefficients based on precipitation rates

  7. Influence of Residual Tumor Volume and Radiation Dose Coverage in Outcomes for Clival Chordoma

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Mark W., E-mail: markmcdonaldmd@gmail.com [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, Indiana (United States); Indiana University Health Proton Therapy Center, Bloomington, Indiana (United States); Linton, Okechukwu R. [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, Indiana (United States); Moore, Michael G.; Ting, Jonathan Y. [Department of Otolaryngology, Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana (United States); Cohen-Gadol, Aaron A.; Shah, Mitesh V. [Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, Indiana (United States); Goodman Campbell Brain and Spine, Indianapolis, Indiana (United States)

    2016-05-01

    Purpose: The purpose of this study was to evaluate factors associated with tumor control in clival chordomas. Methods and Materials: A retrospective review of 39 patients treated with surgery and proton therapy for clival chordomas between 2004 and 2014 was performed. The median prescribed dose was 77.4 Gy (relative biological effectiveness [RBE]); range was 70.2-79.2 Gy (RBE). Minimum and median doses to gross tumor volume (GTV), radiation dose received by 1 cm{sup 3} of GTV (D1cm{sup 3}), and the equivalent uniform dose were calculated. Receiver operating characteristics curves evaluated the predictive sensitivity and specificity for local failure of potential cutpoint values for GTV and D1cm{sup 3}. Results: After a median follow-up of 51 months, the 5-year estimate of local control (LC) was 69.6% (95% confidence interval [CI] 50.0%-89.2%), and overall survival (OS) was 81.4% (95% CI: 65.3%-97.5%). Tumor histology, GTV at the time of radiation, and prescribed radiation dose were significantly associated with local control on multivariate analysis, whereas D1cm{sup 3} was associated with overall survival. Compared to those patients whose conditions remained controlled, patients experiencing tumor failure had statistically significant larger GTVs and lower D1cm{sup 3}, and prescribed and median doses to GTV. A subset of 21 patients with GTV of ≤20 cm{sup 3} and D1cm{sup 3} of >67 Gy (RBE) had a median follow-up of 47 months. The 5-year estimate of local control in this subset was 81.1% (95% CI: 61.7%-100%; P=.004, overall comparison by GTV ≤20 cm{sup 3} stratified by D1cm{sup 3}). A D1cm{sup 3} of 74.5 Gy (RBE) had 80% sensitivity for local control and 60% specificity, whereas a GTV of 9.3 cm{sup 3} had 80% sensitivity for local control and 66.7% specificity. Conclusions: Local control of clival chordomas was associated with both smaller size of residual tumor and more complete high-dose coverage of residual tumor. Multidisciplinary care should seek

  8. SU-E-T-762: Toward Volume-Based Independent Dose Verification as Secondary Check

    International Nuclear Information System (INIS)

    Tachibana, H; Tachibana, R

    2015-01-01

    Purpose: Lung SBRT plan has been shifted to volume prescription technique. However, point dose agreement is still verified using independent dose verification at the secondary check. The volume dose verification is more affected by inhomogeneous correction rather than point dose verification currently used as the check. A feasibility study for volume dose verification was conducted in lung SBRT plan. Methods: Six SBRT plans were collected in our institute. Two dose distributions with / without inhomogeneous correction were generated using Adaptive Convolve (AC) in Pinnacle3. Simple MU Analysis (SMU, Triangle Product, Ishikawa, JP) was used as the independent dose verification software program, in which a modified Clarkson-based algorithm was implemented and radiological path length was computed using CT images independently to the treatment planning system. The agreement in point dose and mean dose between the AC with / without the correction and the SMU were assessed. Results: In the point dose evaluation for the center of the GTV, the difference shows the systematic shift (4.5% ± 1.9 %) in comparison of the AC with the inhomogeneous correction, on the other hands, there was good agreement of 0.2 ± 0.9% between the SMU and the AC without the correction. In the volume evaluation, there were significant differences in mean dose for not only PTV (14.2 ± 5.1 %) but also GTV (8.0 ± 5.1 %) compared to the AC with the correction. Without the correction, the SMU showed good agreement for GTV (1.5 ± 0.9%) as well as PTV (0.9% ± 1.0%). Conclusion: The volume evaluation for secondary check may be possible in homogenous region. However, the volume including the inhomogeneous media would make larger discrepancy. Dose calculation algorithm for independent verification needs to be modified to take into account the inhomogeneous correction

  9. Mixed integer programming with dose-volume constraints in intensity-modulated proton therapy.

    Science.gov (United States)

    Zhang, Pengfei; Fan, Neng; Shan, Jie; Schild, Steven E; Bues, Martin; Liu, Wei

    2017-09-01

    In treatment planning for intensity-modulated proton therapy (IMPT), we aim to deliver the prescribed dose to the target yet minimize the dose to adjacent healthy tissue. Mixed-integer programming (MIP) has been applied in radiation therapy to generate treatment plans. However, MIP has not been used effectively for IMPT treatment planning with dose-volume constraints. In this study, we incorporated dose-volume constraints in an MIP model to generate treatment plans for IMPT. We created a new MIP model for IMPT with dose volume constraints. Two groups of IMPT treatment plans were generated for each of three patients by using MIP models for a total of six plans: one plan was derived with the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) method while the other plan was derived with our MIP model with dose-volume constraints. We then compared these two plans by dose-volume histogram (DVH) indices to evaluate the performance of the new MIP model with dose-volume constraints. In addition, we developed a model to more efficiently find the best balance between tumor coverage and normal tissue protection. The MIP model with dose-volume constraints generates IMPT treatment plans with comparable target dose coverage, target dose homogeneity, and the maximum dose to organs at risk (OARs) compared to treatment plans from the conventional quadratic programming method without any tedious trial-and-error process. Some notable reduction in the mean doses of OARs is observed. The treatment plans from our MIP model with dose-volume constraints can meet all dose-volume constraints for OARs and targets without any tedious trial-and-error process. This model has the potential to automatically generate IMPT plans with consistent plan quality among different treatment planners and across institutions and better protection for important parallel OARs in an effective way. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on

  10. Dose rate from the square volume radiation source

    International Nuclear Information System (INIS)

    Karpov, V.I.

    1978-01-01

    The expression for determining the dose rate from a three-dimensional square flat-parallel source of any dimensions is obtained. A simplified method for integrating the resultant expression is proposed. A comparison of the calculation results with the results by the Monte Carlo method has shown them to coincide within 6-8%. Since buildings and structures consist of rectangular elements, the method is recommended for practical calculations of dose rates in residential buildings

  11. Critical target and dose and dose-rate responses for the induction of chromosomal instability by ionizing radiation

    Science.gov (United States)

    Limoli, C. L.; Corcoran, J. J.; Milligan, J. R.; Ward, J. F.; Morgan, W. F.

    1999-01-01

    To investigate the critical target, dose response and dose-rate response for the induction of chromosomal instability by ionizing radiation, bromodeoxyuridine (BrdU)-substituted and unsubstituted GM10115 cells were exposed to a range of doses (0.1-10 Gy) and different dose rates (0.092-17.45 Gy min(-1)). The status of chromosomal stability was determined by fluorescence in situ hybridization approximately 20 generations after irradiation in clonal populations derived from single progenitor cells surviving acute exposure. Overall, nearly 700 individual clones representing over 140,000 metaphases were analyzed. In cells unsubstituted with BrdU, a dose response was found, where the probability of observing delayed chromosomal instability in any given clone was 3% per gray of X rays. For cells substituted with 25-66% BrdU, however, a dose response was observed only at low doses (1.0 Gy), the incidence of chromosomal instability leveled off. There was an increase in the frequency and complexity of chromosomal instability per unit dose compared to cells unsubstituted with BrdU. The frequency of chromosomal instability appeared to saturate around approximately 30%, an effect which occurred at much lower doses in the presence of BrdU. Changing the gamma-ray dose rate by a factor of 190 (0.092 to 17.45 Gy min(-1)) produced no significant differences in the frequency of chromosomal instability. The enhancement of chromosomal instability promoted by the presence of the BrdU argues that DNA comprises at least one of the critical targets important for the induction of this end point of genomic instability.

  12. Comparison of doses according to change of bladder volume in treatment of prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kyung Tae [Dept. of Radiologic Technology, Dongnam Health University, Suwon (Korea, Republic of); Min, Jung Whan [Dept. of Radiological Technology, Shingu University, Seongnam (Korea, Republic of)

    2017-09-15

    In the case of radiation therapy for prostate cancer, a balloon infused with a certain amount of air through the anus is used to reduce rectal dose. Because of the reason, radiation therapy for prostate cancer has acquired CBCT for daily image induction. In order to maintain the anatomical structure most similar to the first CT taken before treatment, it is pretreated, but it can not be said to be perfectly consistent. In two actual treatment regimens, the volume of the bladder was measured as 45.82 cc and 63.43 cc, and the equivalent diameter was 4.4 cm and 4.9 cm. As a result of this study, the mean volume of the bladder was estimated to be 56.2 cc, 105.6 cc by 20 CBCT. The mean dose of CBCT was 1.74% and the mean Bladder mean dose was 96.67%. In case B, PTV mean dose was 4.31%, Bladder mean Dose was estimated to be 97.35%. The changes in the volume of the bladder resulted in changes in the dose of PTV and bladder. The correlation coefficient of bladder dose according to the change of bladder volume showed linearity of mean dose R2= -0.94. The correlation coefficient of the PTV dose according to the volume change of the bladder showed linearity of mean dose R2= 0.04. It was found that the dose change of PTV was larger than that of bladder according to the change of bladder volume.

  13. Comp Plan: A computer program to generate dose and radiobiological metrics from dose-volume histogram files.

    Science.gov (United States)

    Holloway, Lois Charlotte; Miller, Julie-Anne; Kumar, Shivani; Whelan, Brendan M; Vinod, Shalini K

    2012-01-01

    Treatment planning studies often require the calculation of a large number of dose and radiobiological metrics. To streamline these calculations, a computer program called Comp Plan was developed using MATLAB. Comp Plan calculates common metrics, including equivalent uniform dose, tumor control probability, and normal tissue complication probability from dose-volume histogram data. The dose and radiobiological metrics can be calculated for the original data or for an adjusted fraction size using the linear quadratic model. A homogeneous boost dose can be added to a given structure if desired. The final output is written to an Excel file in a format convenient for further statistical analysis. Comp Plan was verified by independent calculations. A lung treatment planning study comparing 45 plans for 7 structures using up to 6 metrics for each structure was successfully analyzed within approximately 5 minutes with Comp Plan. The code is freely available from the authors on request. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

  14. Limits of dose escalation in lung cancer: a dose-volume histogram analysis comparing coplanar and non-coplanar techniques

    Energy Technology Data Exchange (ETDEWEB)

    Derycke, S.; Van Duyse, B.; Schelfhout, J.; De Neve, W.

    1995-12-01

    To evaluate the feasibility of dose escalation in radiotherapy of inoperable lung cancer, a dose-volume histogram analysis was performed comparing standard coplanar (2D) with non-coplanar (3D) beam arrangements on a non-selected group of 20 patients planned by Sherouse`s GRATISTM 3D-planning system. Serial CT-scanning was performed and 2 Target Volumes (Tvs) were defined. Gross Tumor Volume (GTV) defined a high-dose Target Volume (TV-1). GTV plus location of node stations with > 10% probability of invasion (Minet et al.) defined an intermediate-dose Target Volume (TV-2). However, nodal regions which are incompatible with cure were excluded from TV-2. These are ATS-regions 1, 8, 9 and 14 all left and right as well as heterolateral regions. For 3D-planning, Beam`s Eye View selected (by an experienced planner) beam arrangements were optimised using Superdot, a method of target dose-gradient annihilation developed by Sherouse. A second 3D-planning was performed using 4 beam incidences with maximal angular separation. The linac`s isocenter for the optimal arrangement was located at the geometrical center of gravity of a tetraheder, the tetraheder`s comers being the consecutive positions of the virtual source. This ideal beam arrangement was approximated as close as possible, taking into account technical limitations (patient-couch-gantry collisions). Criteria for tolerance were met if no points inside the spinal cord exceeded 50 Gy and if at least 50% of the lung volume received less than 20Gy. If dose regions below 50 Gy were judged acceptable at TV-2, 2D- as well as 3D-plans allow safe escalation to 80 Gy at TV-1. When TV-2 needed to be encompassed by isodose surfaces exceeding 50Gy, 3D-plans were necessary to limit dose at the spinal cord below tolerance. For large TVs dose is limited by lung tolerance for 3D-plans. An analysis (including NTCP-TCP as cost functions) of rival 3D-plans is being performed.

  15. Critical evaluation of blood volume measurements during hemodialysis.

    Science.gov (United States)

    Dasselaar, Judith J; van der Sande, Frank M; Franssen, Casper F M

    2012-01-01

    Devices that continuously measure relative blood volume (RBV) changes during hemodialysis (HD) are increasingly used for the prevention of dialysis hypotension and fine-tuning of dry weight. However, RBV measurements are subject to various limitations. First, RBV devices provide information on relative blood volume changes but not on absolute blood volume. Since blood volume varies with the hydration status, identical reductions of RBV may result in very different absolute blood volumes at the end of HD. Second, RBV changes underestimate the change of total blood volume due to translocation of lower-hematocrit blood from the microcirculation to the central circulation. Third, changes in posture before and during HD, food intake, exercise, and administration of intravenous fluids may influence the validity of the RBV measurement. Fourth, results obtained by various RBV devices show large interdevice differences. Finally, although a fall in blood volume is an important factor in dialysis hypotension, frank dialysis hypotension only occurs when the cardiovascular compensatory mechanisms can no longer compensate for the reduction in blood volume. Therefore, the dialysis staff should not exclusively focus on RBV, but also search for opportunities in the dialysis prescription to facilitate cardiovascular compensatory mechanisms, e.g. by lowering dialysate temperature. In the opinion of the authors, routine RBV monitoring should be used with caution until the major conceptual and methodological problems that are inherent to the indirect RBV estimation are clarified. Copyright © 2012 S. Karger AG, Basel.

  16. Changes in circulating blood volume after infusion of hydroxyethyl starch 6% in critically ill patients

    DEFF Research Database (Denmark)

    Christensen, P; Andersson, J; Rasmussen, S E

    2001-01-01

    The cardiovascular response to a volume challenge with hydroxyethyl starch (HES) (200/0.5) 6% depends on the relation between the volume of HES 6% infused and the expansion of the blood volume in critically ill patients. However, only relatively limited data exist on the plasma expanding effect...... of infusion of HES 6% in critically ill patients. The purpose of the study was to evaluate the variation in the expansion of the circulating blood volume (CBV) in critically ill patients after infusion of 500 ml of colloid (HES (200/0.5) 6%) using the carbon monoxide method....

  17. Geometrical considerations in dose volume analysis in intracavitary treatment

    International Nuclear Information System (INIS)

    Deshpande, D.D.; Shrivastava, S.K.; Pradhan, A.S.; Viswanathan, P.S.; Dinshaw, K.A.

    1996-01-01

    The present work was aimed at to study the relationship between the volume enclosed by reference iodose surface and various geometrical parameters of the intracavitary applicator in treatment of carcinoma of cervix. Pearshape volume of the reference isodose derived from the Total Reference Air Kerma (TRAK) and the product of its dimensions, height H, width W and thickness T which is dependent on the applicator geometry, were estimated for 100 intracavitary applications treated by Selectron LDR machine. Orthogonal radiographs taken for each patient were used for measurement of actual geometric dimensions of the applicator and carrying out the dosimetry on TP-11 treatment planning system. The dimensions H, W and T of reference isodose surface (60 Gy) were also noted. Ratio of the product HWT and the pearshape volume was found mainly to be a function of colpostat separation and not of other geometrical parameters like maximum vertical and anterio-posterior dimension of the applicator. The ratio remained almost constant for a particular combination of uterine tandem and colpostat. Variation in the ratios were attributed to the non-standard geometry. The ratio of the volume of reference isodose surface to the product of its dimensions in the applicator depends upon the colpostat separation. (orig./MG) [de

  18. Evaluation of dose-volume histograms after prostate seed implantation. 4-year experience

    International Nuclear Information System (INIS)

    Hoinkis, C.; Lehmann, D.; Winkler, C.; Herrmann, T.; Hakenberg, O.W.; Wirth, M.P.

    2004-01-01

    Background and purpose: permanent interstitial brachytherapy by seed implantation is a treatment alternative for low-volume low-risk prostate cancer and a complex interdisciplinary treatment with a learning curve. Dose-volume histograms are used to assess postimplant quality. The authors evaluated their learning curve based on dose-volume histograms and analyzed factors influencing implantation quality. Patients and methods: since 1999, 38 patients with a minimum follow-up of 6 months were treated at the authors' institution with seed implantation using palladium-103 or iodine-125, initially using the preplan method and later real-time planning. Postimplant CT was performed after 4 weeks. The dose-volume indices D90, V100, V150, the D max of pre- and postplans, and the size and position of the volume receiving the prescribed dose (high-dose volume) of the postplans were evaluated. In six patients, postplan imaging both by CT and MRI was used and prostate volumes were compared with preimplant transrectal ultrasound volumes. The first five patients were treated under external supervision. Results: patients were divided into three consecutive groups for analysis of the learning curve (group 1: n = 5 patients treated under external supervision; group 2: n = 13 patients; group 3: n = 20 patients). D90 post for the three groups were 79.3%, 74.2%, and 99.9%, the V100 post were 78.6%, 73.5%, and 88.2%, respectively. The relationship between high-dose volume and prostate volume showed a similar increase as the D90, while the relationship between high-dose volume lying outside the prostate and prostate volume remained constant. The ratio between prostate volumes from transrectal ultrasound and CT imaging decreased with increasing D90 post , while the preplanning D90 and V100 remained constant. The different isotopes used, the method of planning, and the implanted activity per prostate volume did not influence results. Conclusion: a learning curve characterized by an increase

  19. Blood volume measurement with indocyanine green pulse spectrophotometry: dose and site of dye administration

    NARCIS (Netherlands)

    Germans, M.R.; de Witt Hamer, P.C.; van Boven, L.J.; Zwinderman, K.A.H.; Bouma, G.J.

    2010-01-01

    (1) To determine the optimal administration site and dose of indocyanine green (ICG) for blood volume measurement using pulse spectrophotometry, (2) to assess the variation in repeated blood volume measurements for patients after subarachnoid hemorrhage and (3) to evaluate the safety and efficacy of

  20. [Prevention of preeclampsia with low-dose acetyl salicylic acid: critical assessment].

    Science.gov (United States)

    Verrotti, C; Fieni, S; Gualdi, M; Cavatorta, E

    1999-01-01

    The Authors present a critical review of the published literature about the effect of low dose of acido acetilsalicilico on prevention and treatment of preeclampic. Beginning from the effects of low daily dose of acido acetilsalicilico on the pregnancy, the Authors present the published datas from 1970 until today, and suggest the present directions for use of acido acetilsalicilico in pregnancy.

  1. SU-E-T-634: Analysis of Volume Based GYN HDR Brachytherapy Plans for Dose Calculation to Organs At Risk(OAR)

    Energy Technology Data Exchange (ETDEWEB)

    Nair, M; Li, C; White, M; Davis, J [Joe Arrington Cancer Center, Lubbock, TX (United States)

    2014-06-15

    Purpose: We have analyzed the dose volume histogram of 140 CT based HDR brachytherapy plans and evaluated the dose received to OAR ; rectum, bladder and sigmoid colon based on recommendations from ICRU and Image guided brachytherapy working group for cervical cancer . Methods: Our treatment protocol consist of XRT to whole pelvis with 45 Gy at 1.8Gy/fraction followed by 30 Gy at 6 Gy per fraction by HDR brachytherapy in 2 weeks . The CT compatible tandem and ovoid applicators were used and stabilized with radio opaque packing material. The patient was stabilized using special re-locatable implant table and stirrups for reproducibility of the geometry during treatment. The CT scan images were taken at 3mm slice thickness and exported to the treatment planning computer. The OAR structures, bladder, rectum and sigmoid colon were outlined on the images along with the applicators. The prescription dose was targeted to A left and A right as defined in Manchester system and optimized on geometry . The dosimetry was compared on all plans using the parameter Ci.sec.cGy-1 . Using the Dose Volume Histogram (DVH) obtained from the plans the doses to rectum, sigmoid colon and bladder for ICRU defined points and 2cc volume were analyzed and reported. The following criteria were used for limiting the tolerance dose by volume (D2cc) were calculated. The rectum and sigmoid colon doses were limited to <75Gy. The bladder dose was limited to < 90Gy from both XRT and HDR brachytherapy. Results: The average total (XRT+HDRBT) BED values to prescription volume was 120 Gy. Dose 2cc to rectum was 70Gy +/− 17Gy, dose to 2cc bladder was 82+/−32 Gy. The average Ci.sec.cGy-1 calculated for the HDR plans was 6.99 +/− 0.5 Conclusion: The image based treatment planning enabled to evaluati volume based dose to critical structures for clinical interpretation.

  2. Comparison of dose-volume histograms for Tomo therapy, linear accelerator-based 3D conformal radiation therapy, and intensity-modulated radiation therapy

    International Nuclear Information System (INIS)

    Ji, Youn-Sang; Dong, Kyung-Rae; Kim, Chang-Bok; Choi, Seong-Kwan; Chung, Woon-Kwan; Lee, Jong-Woong

    2011-01-01

    Highlights: → Evaluation of DVH from 3D CRT, IMRT and Tomo therapy was conducted for tumor therapy. → The doses of GTV and CTV were compared using DVHs from 3D CRT, IMRT and Tomo therapy. → The GTV was higher when Tomo therapy was used, while the doses of critical organ were low. → They said that Tomo therapy satisfied the goal of radiation therapy more than the others. - Abstract: Evaluation of dose-volume histograms from three-dimensional conformal radiation therapy (3D CRT), intensity-modulated radiation therapy (IMRT), and Tomo therapy was conducted. These three modalities are among the diverse treatment systems available for tumor therapy. Three patients who received tumor therapy for a malignant oligodendroglioma in the cranium, nasopharyngeal carcinoma in the cervical neck, and prostate cancer in the pelvis were selected as study subjects. Therapy plans were made for the three patients before dose-volume histograms were obtained. The doses of the gross tumor volume (GTV) and the clinical target volume (CTV) were compared using the dose-volume histograms obtained from the LINAC-based 3D CRT, IMRT planning station (Varian Eclipse-Varian, version 8.1), and Tomo therapy planning station. In addition, the doses of critical organs in the cranium, cervix, and pelvis that should be protected were compared. The GTV was higher when Tomo therapy was used compared to 3D CRT and the LINAC-based IMRT, while the doses of critical organ tissues that required protection were low. These results demonstrated that Tomo therapy satisfied the ultimate goal of radiation therapy more than the other therapies.

  3. Involved-nodal radiation therapy leads to lower doses to critical organs-at-risk compared to involved-field radiation therapy

    International Nuclear Information System (INIS)

    Mulvihill, David J.; McMichael, Kevin; Goyal, Sharad; Drachtman, Richard; Weiss, Aaron; Khan, Atif J.

    2014-01-01

    Background: Involved field radiotherapy (IFRT) after cytotoxic chemotherapy has become the standard of care in treating pediatric patients with Hodgkin lymphoma. However, recent interest in shrinking the treatment volume to involved node radiotherapy (INRT) may allow lower doses to critical organ structures. We dosimetrically compared IFRT and INRT treatment approaches. Methods: INRT treatment plans were retrospectively constructed from 17 consecutively treated pediatric patients identified with Hodgkin lymphoma who had been previously treated with conventional IFRT. The radiation doses delivered to organs-at-risk (OARs) with virtual INRT treatment plans based on INRT field design were then compared to the original IFRT treatment plans. Metrics for comparison included mean doses to organs and volumes of organ receiving at least 50% of the original prescription dose (V50%). A one-tailed, paired t-test was then performed to verify statistical significance at an alpha level of 0.05. Results: All organs at risk compared in this investigation (kidneys, heart, thyroid, parotids, and lungs) had significantly lower doses of radiation with INRT when compared to IFRT (p < 0.05). Furthermore, the volume of the breast receiving at least 50% of the initial prescription dose was statistically lower in the INRT plans. Conclusions: Utilizing the concept of INRT results in a reduction of radiation dose to critical organ structures in pediatric patients with Hodgkin lymphoma when compared to the more traditional method of IFRT

  4. Nuclear criticality safety experiments, calculations, and analyses: 1958 to 1982. Volume 1. Lookup tables

    International Nuclear Information System (INIS)

    Koponen, B.L.; Hampel, V.E.

    1982-01-01

    This compilation contains 688 complete summaries of papers on nuclear criticality safety as presented at meetings of the American Nuclear Society (ANS). The selected papers contain criticality parameters for fissile materials derived from experiments and calculations, as well as criticality safety analyses for fissile material processing, transport, and storage. The compilation was developed as a component of the Nuclear Criticality Information System (NCIS) now under development at the Lawrence Livermore National Laboratory. The compilation is presented in two volumes: Volume 1 contains a directory to the ANS Transaction volume and page number where each summary was originally published, the author concordance, and the subject concordance derived from the keyphrases in titles. Volume 2 contains - in chronological order - the full-text summaries, reproduced here by permission of the American Nuclear Society from their Transactions, volumes 1-41

  5. Volume pinning force and upper critical field of irradiated Nb3Sn

    International Nuclear Information System (INIS)

    Maier, P.; Seibt, E.

    1981-01-01

    Irradiation by neutrons and ions in A15 superconductors (Nb 3 Sn, V 3 Ga) exerts a stronger influence on the pinning behavior than in nonordered alloys (NbTi). In this work it is shown for deuteron irradiated Nb 3 /Sn wires prepared by the bronze process that the dose curve of the volume pinning force P/sub V/ can be conveniently described by a sum of two terms, due to the grain boundary pinning and to the radiation pinning, respectively. After deduction of the contribution by the radiation-induced pinning centers, good agreement is obtained between the measured P/sub V/ values and those calculated using the upper critical field B/sub c/2 and the transition temperature T/sub c/ on the basis of the irradiation fluence. The use of a theoretical relationship between B/sub c/2 and T/sub c/ is supported by measured values. Application to multifilamentary superconductors with high current carrying capabilities simplifies the calculation of P/sub V/, since the radiation induced volume pinning force can be neglected

  6. Potential implications of the bystander effect on TCP and EUD when considering target volume dose heterogeneity.

    Science.gov (United States)

    Balderson, Michael J; Kirkby, Charles

    2015-01-01

    In light of in vitro evidence suggesting that radiation-induced bystander effects may enhance non-local cell killing, there is potential for impact on radiotherapy treatment planning paradigms such as the goal of delivering a uniform dose throughout the clinical target volume (CTV). This work applies a bystander effect model to calculate equivalent uniform dose (EUD) and tumor control probability (TCP) for external beam prostate treatment and compares the results with a more common model where local response is dictated exclusively by local absorbed dose. The broad assumptions applied in the bystander effect model are intended to place an upper limit on the extent of the results in a clinical context. EUD and TCP of a prostate cancer target volume under conditions of increasing dose heterogeneity were calculated using two models: One incorporating bystander effects derived from previously published in vitro bystander data ( McMahon et al. 2012 , 2013a); and one using a common linear-quadratic (LQ) response that relies exclusively on local absorbed dose. Dose through the CTV was modelled as a normal distribution, where the degree of heterogeneity was then dictated by changing the standard deviation (SD). Also, a representative clinical dose distribution was examined as cold (low dose) sub-volumes were systematically introduced. The bystander model suggests a moderate degree of dose heterogeneity throughout a target volume will yield as good or better outcome compared to a uniform dose in terms of EUD and TCP. For a typical intermediate risk prostate prescription of 78 Gy over 39 fractions maxima in EUD and TCP as a function of increasing SD occurred at SD ∼ 5 Gy. The plots only dropped below the uniform dose values for SD ∼ 10 Gy, almost 13% of the prescribed dose. Small, but potentially significant differences in the outcome metrics between the models were identified in the clinically-derived dose distribution as cold sub-volumes were introduced. In terms of

  7. A prospective evaluation of hippocampal radiation dose volume effects and memory deficits following cranial irradiation.

    Science.gov (United States)

    Ma, Ting Martin; Grimm, Jimm; McIntyre, Riley; Anderson-Keightly, Heather; Kleinberg, Lawrence R; Hales, Russell K; Moore, Joseph; Vannorsdall, Tracy; Redmond, Kristin J

    2017-11-01

    To prospectively evaluate hippocampal radiation dose volume effects and memory decline following cranial irradiation. Effects of hippocampal radiation over a wide range of doses were investigated by combining data from three prospective studies. In one, adults with small cell lung cancer received hippocampal-avoidance prophylactic cranial irradiation. In the other two, adults with glioblastoma multiforme received neural progenitor cell sparing radiation or no sparing with extra dose delivered to subventricular zone. Memory was measured by the Hopkins Verbal Learning Test-Revised Delayed Recall (HVLT-R DR) at 6 months after radiation. Dose-volume histograms were generated and dose-response data were fitted to a nonlinear model. Of 60 patients enrolled, 30 were analyzable based on HVLT-R DR testing completion status, baseline HVLT-R DR and intracranial metastasis/recurrence or prior hippocampal resection status. We observed a dose-response of radiation to the hippocampus with regard to decline in HVLT-R DR. D50% of the bilateral hippocampi of 22.1 Gy is associated with 20% risk of decline. This prospective study demonstrates an association between hippocampal dose volume effects and memory decline measured by HVLT-R DR over a wide dose range. These data support a potential benefit of hippocampal sparing and encourage continued trial enrollment. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Measuring the absorbed dose in critical organs during low rate dose brachytherapy with 137 Cs using thermoluminescent dosemeters

    International Nuclear Information System (INIS)

    Torres, A.; Gonzalez, P.R.; Furetta, C.; Azorin, J.; Andres, U.; Mendez, G.

    2003-01-01

    Intracavitary Brachytherapy is one of the most used methods for the treatment of the cervical-uterine cancer. This treatment consists in the insertion of low rate dose 137 Cs sources into the patient. The most used system for the treatment dose planning is that of Manchester. This planning is based on sources, which are considered fixed during the treatment. However, the experience has shown that, during the treatment, the sources could be displaced from its initial position, changing the dose from that previously prescribed. For this reason, it is necessary to make measurements of the absorbed dose to the surrounding organs (mainly bladder and rectum). This paper presents the results of measuring the absorbed dose using home-made LiF: Mg, Cu, P + Ptfe thermoluminescent dosimeters (TLD). Measurements were carried out in-vivo during 20 minutes at the beginning and at the end of the treatments. Results showed that the absorbed dose to the critical organs vary significantly due to the movement of the patient during the treatment. (Author)

  9. ROMPS critical design review. Volume 2: Robot module design documentation

    Science.gov (United States)

    Dobbs, M. E.

    1992-01-01

    The robot module design documentation for the Remote Operated Materials Processing in Space (ROMPS) experiment is compiled. This volume presents the following information: robot module modifications; Easylab commands definitions and flowcharts; Easylab program definitions and flowcharts; robot module fault conditions and structure charts; and C-DOC flow structure and cross references.

  10. Critical Evaluation of Blood Volume Measurements during Hemodialysis

    NARCIS (Netherlands)

    Dasselaar, Judith J.; van der Sande, Frank M.; Franssen, Casper F. M.

    2012-01-01

    Devices that continuously measure relative blood volume (RBV) changes during hemodialysis (HD) are increasingly used for the prevention of dialysis hypotension and fine-tuning of dry weight. However, RBV measurements are subject to various limitations. First, RBV devices provide information on

  11. Clinical impact of MRI assisted dose volume adaptation and dose escalation in brachytherapy of locally advanced cervix cancer

    International Nuclear Information System (INIS)

    Poetter, Richard; Dimopoulos, Johannes; Georg, Petra; Lang, Stefan; Waldhaeusl, Claudia; Wachter-Gerstner, Natascha; Weitmann, Hajo; Reinthaller, Alexander; Knocke, Tomas Hendrik; Wachter, Stefan; Kirisits, Christian

    2007-01-01

    Background: To investigate the clinical impact of MRI based cervix cancer brachytherapy combined with external beam radiochemotherapy applying dose volume adaptation and dose escalation in a consecutive group of patients with locally advanced cervix cancer. Methods: In the period 1998-2003, 145 patients with cervix cancer stages IB-IVA were treated with definitive radiotherapy +/- cisplatin chemotherapy. Median age was 60 years. In 67 patients, the tumour size was 2-5 cm, in 78 patients it was >5 cm. In 29 cases the standard intracavitary technique was combined with interstitial brachytherapy. Total prescribed dose was 80-85 Gy (total biologically equivalent dose in 2 Gy fractions). Since 2001, MRI based treatment planning integrated systematic concepts for High Risk Clinical Target Volume (HR CTV) and organs at risk (OAR), biological modelling, Dose-Volume-Histogram analysis, dose-volume-adaptation (D90, D 2 cm 3 ), and dose escalation, if appropriate and feasible. Findings: Dose volume adaptation was performed in 130/145 patients. The mean D90 during the whole period was 86 Gy, with a mean D90 of 81 Gy and 90 Gy during the first and second period, respectively (p 5 cm it was 71% in 1998-2000 and 90% in 2001-2003 (p = 0.05). Progression free survival (PFS) for true pelvis (local control) was 85%, PFS for distant metastases was 80%, both at 3 years. Local control for tumours >5 cm was 64% in 1998-2000 and 82% in 2001-2003 (p = 0.09) and 100% and 96%, respectively, for tumours 2-5 cm. PFS for distant metastases remained the same during the two treatment periods with 79% and 80%. Overall survival (OS) was 58%, and cancer-specific survival (CSS) was 68% at 3 years. In the two different periods improvement in OS was from 53% to 64% (p = 0.03) and in CSS from 62% to 74% (p = 0.13). Improvement occurred only in tumours >5 cm: OS 28% versus 58% (p = 0.003); CSS 40% versus 62% (p = 0.07). Actuarial late morbidity rate (LENT SOMA, grades 3 and 4) at 3 years was

  12. Tumor Volume-Adapted Dosing in Stereotactic Ablative Radiotherapy of Lung Tumors

    Energy Technology Data Exchange (ETDEWEB)

    Trakul, Nicholas; Chang, Christine N.; Harris, Jeremy [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA (United States); Chapman, Christopher [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA (United States); University of Michigan School of Medicine, Ann Arbor, MI (United States); Rao, Aarti [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA (United States); University of California, Davis, School of Medicine, Davis, CA (United States); Shen, John [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA (United States); University of California, Irvine, School of Medicine, Irvine, CA (United States); Quinlan-Davidson, Sean [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA (United States); Department of Radiation Oncology, McMaster University, Juravinski Cancer Centre, Hamilton, Ontario (Canada); Filion, Edith J. [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA (United States); Departement de Medecine, Service de Radio-Oncologie, Centre Hospitalier de l' Universite de Montreal, Montreal, Quebec (Canada); Wakelee, Heather A.; Colevas, A. Dimitrios [Department of Medicine, Division of Oncology, Stanford University School of Medicine, Stanford, CA (United States); Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA (United States); Whyte, Richard I. [Department of Cardiothoracic Surgery, Division of General Thoracic Surgery, Stanford University School of Medicine, Stanford, CA (United States); Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA (United States); and others

    2012-09-01

    Purpose: Current stereotactic ablative radiotherapy (SABR) protocols for lung tumors prescribe a uniform dose regimen irrespective of tumor size. We report the outcomes of a lung tumor volume-adapted SABR dosing strategy. Methods and Materials: We retrospectively reviewed the outcomes in 111 patients with a total of 138 primary or metastatic lung tumors treated by SABR, including local control, regional control, distant metastasis, overall survival, and treatment toxicity. We also performed subset analysis on 83 patients with 97 tumors treated with a volume-adapted dosing strategy in which small tumors (gross tumor volume <12 mL) received single-fraction regimens with biologically effective doses (BED) <100 Gy (total dose, 18-25 Gy) (Group 1), and larger tumors (gross tumor volume {>=}12 mL) received multifraction regimens with BED {>=}100 Gy (total dose, 50-60 Gy in three to four fractions) (Group 2). Results: The median follow-up time was 13.5 months. Local control for Groups 1 and 2 was 91.4% and 92.5%, respectively (p = 0.24) at 12 months. For primary lung tumors only (excluding metastases), local control was 92.6% and 91.7%, respectively (p = 0.58). Regional control, freedom from distant metastasis, and overall survival did not differ significantly between Groups 1 and 2. Rates of radiation pneumonitis, chest wall toxicity, and esophagitis were low in both groups, but all Grade 3 toxicities developed in Group 2 (p = 0.02). Conclusion: A volume-adapted dosing approach for SABR of lung tumors seems to provide excellent local control for both small- and large-volume tumors and may reduce toxicity.

  13. Tumor Volume-Adapted Dosing in Stereotactic Ablative Radiotherapy of Lung Tumors

    International Nuclear Information System (INIS)

    Trakul, Nicholas; Chang, Christine N.; Harris, Jeremy; Chapman, Christopher; Rao, Aarti; Shen, John; Quinlan-Davidson, Sean; Filion, Edith J.; Wakelee, Heather A.; Colevas, A. Dimitrios; Whyte, Richard I.

    2012-01-01

    Purpose: Current stereotactic ablative radiotherapy (SABR) protocols for lung tumors prescribe a uniform dose regimen irrespective of tumor size. We report the outcomes of a lung tumor volume-adapted SABR dosing strategy. Methods and Materials: We retrospectively reviewed the outcomes in 111 patients with a total of 138 primary or metastatic lung tumors treated by SABR, including local control, regional control, distant metastasis, overall survival, and treatment toxicity. We also performed subset analysis on 83 patients with 97 tumors treated with a volume-adapted dosing strategy in which small tumors (gross tumor volume <12 mL) received single-fraction regimens with biologically effective doses (BED) <100 Gy (total dose, 18–25 Gy) (Group 1), and larger tumors (gross tumor volume ≥12 mL) received multifraction regimens with BED ≥100 Gy (total dose, 50–60 Gy in three to four fractions) (Group 2). Results: The median follow-up time was 13.5 months. Local control for Groups 1 and 2 was 91.4% and 92.5%, respectively (p = 0.24) at 12 months. For primary lung tumors only (excluding metastases), local control was 92.6% and 91.7%, respectively (p = 0.58). Regional control, freedom from distant metastasis, and overall survival did not differ significantly between Groups 1 and 2. Rates of radiation pneumonitis, chest wall toxicity, and esophagitis were low in both groups, but all Grade 3 toxicities developed in Group 2 (p = 0.02). Conclusion: A volume-adapted dosing approach for SABR of lung tumors seems to provide excellent local control for both small- and large-volume tumors and may reduce toxicity.

  14. Tools for the analysis of dose optimization: I. Effect-volume histogram

    International Nuclear Information System (INIS)

    Alber, M.; Nuesslin, F.

    2002-01-01

    With the advent of dose optimization algorithms, predominantly for intensity-modulated radiotherapy (IMRT), computer software has progressed beyond the point of being merely a tool at the hands of an expert and has become an active, independent mediator of the dosimetric conflicts between treatment goals and risks. To understand and control the internal decision finding as well as to provide means to influence it, a tool for the analysis of the dose distribution is presented which reveals the decision-making process performed by the algorithm. The internal trade-offs between partial volumes receiving high or low doses are driven by functions which attribute a weight to each volume element. The statistics of the distribution of these weights is cast into an effect-volume histogram (EVH) in analogy to dose-volume histograms. The analysis of the EVH reveals which traits of the optimum dose distribution result from the defined objectives, and which are a random consequence of under- or misspecification of treatment goals. The EVH can further assist in the process of finding suitable objectives and balancing conflicting objectives. If biologically inspired objectives are used, the EVH shows the distribution of local dose effect relative to the prescribed level. (author)

  15. Equivalent dose, effective dose and risk assessment from panoramic radiography to the critical organs of head and neck region

    International Nuclear Information System (INIS)

    Cho, Bong Hae; Nah, Kyung Soo; Lee, Ae Ryeon

    1995-01-01

    The purpose of this study was to evaluate the equivalent and effective dose, and estimate radiation risk to the critical organs of head and neck region from the use of adult and child mode in panoramic radiography. The results were as follows. 1. The salivary glands showed the highest equivalent and effective dose in adult and child mode. The equivalent and effective dose in adult mode were 837 μSv and 20.93 μSv, those in child mode were 462 μSv and 11.54 μSv, respectively. 2. Total effective doses to the critical head and neck organs were estimated 34.2l μSv in adult mode, 20.14 μSv in child mode. From these data, the probabilities of stochastic effect from adult and child mode were 2.50xl0 -6 and 1.47x10 -6 3. The other remainder showed the greatest risk of fatal cancer. The risk estimate were 4.5 and 2.7 fatal malignancies in adult and child mode from million examinations. The bone marrow and thyroid gland showed about 0.1 fatal cancer in adult. and child mode from these examinations.

  16. Equivalent dose, effective dose and risk assessment from panoramic radiography to the critical organs of head and neck region

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Bong Hae; Nah, Kyung Soo [Dept. of Dental Radiology, College of Dentistry, Pusan National University, Pusan (Korea, Republic of); Lee, Ae Ryeon [Dept. of Pediatric Dentistry, College of Dentistry, Pusan National University, Pusan (Korea, Republic of)

    1995-08-15

    The purpose of this study was to evaluate the equivalent and effective dose, and estimate radiation risk to the critical organs of head and neck region from the use of adult and child mode in panoramic radiography. The results were as follows. 1. The salivary glands showed the highest equivalent and effective dose in adult and child mode. The equivalent and effective dose in adult mode were 837 {mu}Sv and 20.93 {mu}Sv, those in child mode were 462 {mu}Sv and 11.54 {mu}Sv, respectively. 2. Total effective doses to the critical head and neck organs were estimated 34.2l {mu}Sv in adult mode, 20.14 {mu}Sv in child mode. From these data, the probabilities of stochastic effect from adult and child mode were 2.50xl0{sup -6} and 1.47x10{sup -6} 3. The other remainder showed the greatest risk of fatal cancer. The risk estimate were 4.5 and 2.7 fatal malignancies in adult and child mode from million examinations. The bone marrow and thyroid gland showed about 0.1 fatal cancer in adult. and child mode from these examinations.

  17. Use of Monte Carlo Simulations to Determine Optimal Carbapenem Dosing in Critically Ill Patients Receiving Prolonged Intermittent Renal Replacement Therapy.

    Science.gov (United States)

    Lewis, Susan J; Kays, Michael B; Mueller, Bruce A

    2016-10-01

    Pharmacokinetic/pharmacodynamic analyses with Monte Carlo simulations (MCSs) can be used to integrate prior information on model parameters into a new renal replacement therapy (RRT) to develop optimal drug dosing when pharmacokinetic trials are not feasible. This study used MCSs to determine initial doripenem, imipenem, meropenem, and ertapenem dosing regimens for critically ill patients receiving prolonged intermittent RRT (PIRRT). Published body weights and pharmacokinetic parameter estimates (nonrenal clearance, free fraction, volume of distribution, extraction coefficients) with variability were used to develop a pharmacokinetic model. MCS of 5000 patients evaluated multiple regimens in 4 different PIRRT effluent/duration combinations (4 L/h × 10 hours or 5 L/h × 8 hours in hemodialysis or hemofiltration) occurring at the beginning or 14-16 hours after drug infusion. The probability of target attainment (PTA) was calculated using ≥40% free serum concentrations above 4 times the minimum inhibitory concentration (MIC) for the first 48 hours. Optimal doses were defined as the smallest daily dose achieving ≥90% PTA in all PIRRT combinations. At the MIC of 2 mg/L for Pseudomonas aeruginosa, optimal doses were doripenem 750 mg every 8 hours, imipenem 1 g every 8 hours or 750 mg every 6 hours, and meropenem 1 g every 12 hours or 1 g pre- and post-PIRRT. Ertapenem 500 mg followed by 500 mg post-PIRRT was optimal at the MIC of 1 mg/L for Streptococcus pneumoniae. Incorporating data from critically ill patients receiving RRT into MCS resulted in markedly different carbapenem dosing regimens in PIRRT from those recommended for conventional RRTs because of the unique drug clearance characteristics of PIRRT. These results warrant clinical validation. © 2016, The American College of Clinical Pharmacology.

  18. Dose and volume specification for reporting NCT. An ICRU-IAEA initiative

    International Nuclear Information System (INIS)

    Wambersie, A.; Gahbauer, R.A.; Whitmore, G.; Levin, C.V.

    2000-01-01

    The present recommendations result from of an ICRU-IAEA initiative for harmonization of reporting NCT (Neutron Capture Therapy). As stated by the ISNCT, harmonization of reporting is required to understand what has actually been done and interpret the clinical results on the basis of reliable information. Prescription of a treatment remains the responsibility of the radiation oncologist in charge of the patient. Complete oncological data should be reported, including Gross Tumor Volume (GTV) and Clinical Target Volume (CTV) as well as Planning Target Volume (PTV), Treated Volume and Organs/Structures at Risk. A reference point for reporting dose should be selected in the central part of the PTV/CTV. At each point of interest, the four components contributing to the absorbed dose and the weighting factors applied to take account of the RBE (Relative Biological Effectiveness) differences should be specified. (author)

  19. Investigations on the necessity of dose calculations for several planes of the target volume

    International Nuclear Information System (INIS)

    Richter, E.

    1987-01-01

    In radiotherapy planning, the shape of a target volume can at present be exactly delimited by means of computed tomography. A method often applied is to project the largest target volume scan on the plane of the central ray and to calculate the dose in this plane. This method does not allow to take into account any change of the target volume scan which will be mainly due to the body contours of the patient. The results of dose calculations made in several planes for pharyngeal and laryngeal tumors are presented. With this procedure, 33 out of 60 irradiation techniques for nine tumor sites meet the requirements with regard to the central ray plane. If several planes are regarded, this is only true for ten irradiation plans. If is therefore absolutely necessary to calculate the doses of several planes if the target volume has an irregular shape or if the body contours vary considerably. This is the only way to prevent a false treatment caused by possibly severe dose excesses or dose insufficiencies in radiotherapy. (orig.) [de

  20. Prostate volume change after radioactive seed implantation: Possible benefit of improved dose volume histogram with perioperative steroid

    International Nuclear Information System (INIS)

    Speight, Joycelyn L.; Shinohara, Katsuto; Pickett, Barby; Weinberg, Vivian K.; Hsu, I. Chow Joe; Roach, Mack

    2000-01-01

    Purpose: To evaluate the changes in prostate volume associated with radioactive seed implantation and identify factors that influence prostate swelling. Methods and Materials: Between June 1997 and August 1999, 161 patients implanted for prostate carcinoma at the University of California, San Francisco, had prostate volume measurements taken at 4 time points (preplan, preimplant, postimplant, postimplant dosimetry). Patient records were reviewed for treatment with perioperative steroids, hormone therapy (nHT), and external beam radiotherapy (EBRT). One and 2-way analysis of variance (ANOVA) methods were used to test differences in mean effects among patient subsets. Results: A mean 20% volume increase was noted immediately postimplant overall (p < 0.0001), and even with EBRT and/or HT. Steroids were associated with a mean volume decrease of 19.9%, by 3-4 weeks post-procedure (p < 0.0001). Without steroids, only a 3.8% mean change was seen (p = ns). Steroid use resulted in a significant increase in mean dose-volume histogram (DVH) (p = 0.001); however, this benefit was only observed among patients who did not receive steroid. A consistently high DVH occurred with steroid use. Conclusion: A significant decrease in prostate volume and improved DVH are associated with steroid use. The diminished benefit of steroid use and higher mean DVH achieved in later years suggests the existence of a significant 'learning curve' for brachytherapy procedures.

  1. SU-F-BRD-14: Dose Weighted Linear Energy Transfer Analysis of Critical Structures in Proton Therapy of Pediatric Brain Tumor Patients

    Energy Technology Data Exchange (ETDEWEB)

    Pirlepesov, F.; Shin, J.; Moskvin, V. P.; Gray, J.; Hua, C.; Gajjar, A.; Krasin, M. J.; Merchant, T. E.; Farr, J. B. [St. Jude Children’s Research Hospital, Memphis, TN (United States); Li, Z. [University of Florida Proton Therapy Institute, Jacksonville, FL (United States)

    2015-06-15

    Purpose: Dose weighted Linear Energy Transfer (LETd) analysis of critical structures may be useful in understanding the side effects of the proton therapy. The objective is to analyze the differences between LETd and dose distributions in brain tumor patients receiving double scattering proton therapy, to quantify LETd variation in critical organs, and to identify beam arrangements contributing to high LETd in critical organs. Methods: Monte Carlo simulations of 9 pediatric brain tumor patients were performed. The treatment plans were reconstructed with the TOPAS Monte Carlo code to calculate LETd and dose. The beam data were reconstructed proximal to the aperture of the double scattering nozzle. The dose and LETd to target and critical organs including brain stem, optic chiasm, lens, optic nerve, pituitary gland, and hypothalamus were computed for each beam. Results: Greater variability in LETd compared to dose was observed in the brainstem for patients with a variety of tumor types including 5 patients with tumors located in the posterior fossa. Approximately 20%–44% brainstem volume received LETd of 5kev/µm or greater from beams within gantry angles 180°±30° for 5 patients treated with a 3 beam arrangement. Critical organs received higher LETd when located in the vicinity of the beam distal edge. Conclusion: This study presents a novel strategy in the evaluation of the proton treatment impact on critical organs. While the dose to critical organs is confined below the required limits, the LETd may have significant variation. Critical organs in the vicinity of beam distal edge receive higher LETd and depended on beam arrangement, e.g. in posterior fossa tumor treatment, brainstem receive higher LETd from posterior-anterior beams. This study shows importance of the LETd analysis of the radiation impact on the critical organs in proton therapy and may be used to explain clinical imaging observations after therapy.

  2. SCALE-4 analysis of pressurized water reactor critical configurations. Volume 1: Summary

    International Nuclear Information System (INIS)

    DeHart, M.D.

    1995-03-01

    The requirements of ANSI/ANS 8.1 specify that calculational methods for away-from-reactor criticality safety analyses be validated against experimental measurements. If credit is to be taken for the reduced reactivity of burned or spent fuel relative to its original fresh composition, it is necessary to benchmark computational methods used in determining such reactivity worth against spent fuel reactivity measurements. This report summarizes a portion of the ongoing effort to benchmark away-from-reactor criticality analysis methods using critical configurations from commercial pressurized water reactors (PWR). The analysis methodology utilized for all calculations in this report is based on the modules and data associated with the SCALE-4 code system. Each of the five volumes comprising this report provides an overview of the methodology applied. Subsequent volumes also describe in detail the approach taken in performing criticality calculations for these PWR configurations: Volume 2 describes criticality calculations for the Tennessee Valley Authority's Sequoyah Unit 2 reactor for Cycle 3; Volume 3 documents the analysis of Virginia Power's Surry Unit 1 reactor for the Cycle 2 core; Volume 4 documents the calculations performed based on GPU Nuclear Corporation's Three Mile Island Unit 1 Cycle 5 core; and, lastly, Volume 5 describes the analysis of Virginia Power's North Anna Unit 1 Cycle 5 core. Each of the reactor-specific volumes provides the details of calculations performed to determine the effective multiplication factor for each reactor core for one or more critical configurations using the SCALE-4 system; these results are summarized in this volume. Differences between the core designs and their possible impact on the criticality calculations are also discussed. Finally, results are presented for additional analyses performed to verify that solutions were sufficiently converged

  3. Evaluation of dose equivalent rate distribution in JCO critical accident by radiation transport calculation

    CERN Document Server

    Sakamoto, Y

    2002-01-01

    In the prevention of nuclear disaster, there needs the information on the dose equivalent rate distribution inside and outside the site, and energy spectra. The three dimensional radiation transport calculation code is a useful tool for the site specific detailed analysis with the consideration of facility structures. It is important in the prediction of individual doses in the future countermeasure that the reliability of the evaluation methods of dose equivalent rate distribution and energy spectra by using of Monte Carlo radiation transport calculation code, and the factors which influence the dose equivalent rate distribution outside the site are confirmed. The reliability of radiation transport calculation code and the influence factors of dose equivalent rate distribution were examined through the analyses of critical accident at JCO's uranium processing plant occurred on September 30, 1999. The radiation transport calculations including the burn-up calculations were done by using of the structural info...

  4. SU-E-T-578: On Definition of Minimum and Maximum Dose for Target Volume

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Y; Yu, J; Xiao, Y [Thomas Jefferson University Hospital, Philadelphia, PA (United States)

    2015-06-15

    Purpose: This study aims to investigate the impact of different minimum and maximum dose definitions in radiotherapy treatment plan quality evaluation criteria by using tumor control probability (TCP) models. Methods: Dosimetric criteria used in RTOG 1308 protocol are used in the investigation. RTOG 1308 is a phase III randomized trial comparing overall survival after photon versus proton chemoradiotherapy for inoperable stage II-IIIB NSCLC. The prescription dose for planning target volume (PTV) is 70Gy. Maximum dose (Dmax) should not exceed 84Gy and minimum dose (Dmin) should not go below 59.5Gy in order for the plan to be “per protocol” (satisfactory).A mathematical model that simulates the characteristics of PTV dose volume histogram (DVH) curve with normalized volume is built. The Dmax and Dmin are noted as percentage volumes Dη% and D(100-δ)%, with η and d ranging from 0 to 3.5. The model includes three straight line sections and goes through four points: D95%= 70Gy, Dη%= 84Gy, D(100-δ)%= 59.5 Gy, and D100%= 0Gy. For each set of η and δ, the TCP value is calculated using the inhomogeneously irradiated tumor logistic model with D50= 74.5Gy and γ50=3.52. Results: TCP varies within 0.9% with η; and δ values between 0 and 1. With η and η varies between 0 and 2, TCP change was up to 2.4%. With η and δ variations from 0 to 3.5, maximum of 8.3% TCP difference is seen. Conclusion: When defined maximum and minimum volume varied more than 2%, significant TCP variations were seen. It is recommended less than 2% volume used in definition of Dmax or Dmin for target dosimetric evaluation criteria. This project was supported by NIH grants U10CA180868, U10CA180822, U24CA180803, U24CA12014 and PA CURE Grant.

  5. Dose-volume factors correlating with trismus following chemoradiation for head and neck cancer.

    Science.gov (United States)

    Rao, Shyam D; Saleh, Ziad H; Setton, Jeremy; Tam, Moses; McBride, Sean M; Riaz, Nadeem; Deasy, Joseph O; Lee, Nancy Y

    2016-01-01

    To investigate the dose-volume factors in mastication muscles that are implicated as possible causes of trismus in patients following treatment with intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy for head and neck cancers. All evaluable patients treated at our institution between January 2004 and April 2009 with chemotherapy and IMRT for squamous cell cancers of the oropharynx, nasopharynx, hypopharynx or larynx were included in this analysis (N = 421). Trismus was assessed using CTCAE 4.0. Bi-lateral masseter, temporalis, lateral pterygoid and medial pterygoid muscles were delineated on axial computed tomography (CT) treatment planning images, and dose-volume parameters were extracted to investigate univariate and multimetric correlations. Forty-six patients (10.9%) were observed to have chronic trismus of grade 1 or greater. From analysis of baseline patient characteristics, toxicity correlated with primary site and patient age. From dose-volume analysis, the steepest dose thresholds and highest correlations were seen for mean dose to ipsilateral masseter (Spearman's rank correlation coefficient Rs = 0.25) and medial pterygoid (Rs = 0.23) muscles. Lyman-Kutcher-Burman modeling showed highest correlations for the same muscles. The best correlation for multimetric logistic regression modeling was with V68Gy to the ipsilateral medial pterygoid (Rs = 0.29). Chemoradiation-induced trismus remains a problem particularly for patients with oropharyngeal carcinoma. Strong dose-volume correlations support the hypothesis that limiting dose to the ipsilateral masseter muscle and, in particular, the medial pterygoid muscle may reduce the likelihood of trismus.

  6. MLC tracking for lung SABR reduces planning target volumes and dose to organs at risk.

    Science.gov (United States)

    Caillet, Vincent; Keall, Paul J; Colvill, Emma; Hardcastle, Nicholas; O'Brien, Ricky; Szymura, Kathryn; Booth, Jeremy T

    2017-07-01

    Assess the dosimetric impact of multi-leaf collimator (MLC) tracking and mid-ventilation (midV) planning compared with the internal target volume (ITV)-based planning approach for lung Stereotactic Ablative Body Radiotherapy (SABR). Ten lung SABR patients originally treated with an ITV-based plan were re-planned according to MLC tracking and midV planning schemes. All plans were delivered on a linac to a motion phantom in a simulated treatment with real lung motions. Delivered dose was reconstructed in patient planning scans. ITV-based, tracking and midV regimes were compared at the planning and delivered stages based on PTV volume and dose metrics for the GTV and OAR. MLC tracking and midV schemes yielded favourable outcomes compared with ITV-based plans. Average reduction in PTV volume was (MLC tracking/MidV) 33.9%/22%. GTV dose coverage performed better with MLC tracking than the other regimes. Reduction in dose to OAR were for the lung (mean lung dose, 0.8Gy/0.2Gy), oesophagus (D3cc, 1.9Gy/1.4Gy), great vessels (D10cc, 3.2Gy/1.3Gy), trachea (D4cc, 1.1Gy/0.9Gy), heart (D1cc, 2.0Gy/0.5Gy) and spinal cord (D0.03cc, 0.5Gy/-0.1Gy). MLC tracking showed reduction in PTV volume, superior GTV dose coverage and organ dose sparing than MidV and ITV-based strategies. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. A two isocenter IMRT technique with a controlled junction dose for long volume targets

    International Nuclear Information System (INIS)

    Zeng, G G; Heaton, R K; Catton, C N; Chung, P W; O'Sullivan, B; Lau, M; Parent, A; Jaffray, D A

    2007-01-01

    Most IMRT techniques have been designed to treat targets smaller than the field size of conventional linac accelerators. In order to overcome the field size restrictions in applying IMRT, we developed a two isocenter IMRT technique to treat long volume targets. The technique exploits an extended dose gradient throughout a junction region of 4-6 cm to minimize the impact of field match errors on a junction dose and manipulates the inverse planning and IMRT segments to fill in the dose gradient and achieve dose uniformity. Techniques for abutting both conventional fields with IMRT ('Static + IMRT') and IMRT fields ('IMRT + IMRT') using two separate isocenters have been developed. Five long volume sarcoma cases have been planned in Pinnacle (Philips, Madison, USA) using Elekta Synergy and Varian 2100EX linacs; two of the cases were clinically treated with this technique. Advantages were demonstrated with well-controlled junction target uniformity and tolerance to setup uncertainties. The junction target dose heterogeneity was controlled at a level of ±5%; for 3 mm setup errors at the field edges, the junction target dose changed less than 5% and the dose sparing to organs at risk (OARs) was maintained. Film measurements confirmed the treatment planning results

  8. A model to incorporate organ deformation in the evaluation of dose/volume relationship

    International Nuclear Information System (INIS)

    Yan, D.; Jaffray, D.; Wong, J.; Brabbins, D.; Martinez, A. A.

    1997-01-01

    Purpose: Measurements of internal organ motion have demonstrated that daily organ deformation exists during the course of radiation treatment. However, a model to evaluate the resultant dose delivered to a daily deformed organ remains a difficult challenge. Current methods which model such organ deformation as rigid body motion in the dose calculation for treatment planning evaluation are incorrect and misleading. In this study, a new model for treatment planning evaluation is introduced which incorporates patient specific information of daily organ deformation and setup variation. The model was also used to retrospectively analyze the actual treatment data measured using daily CT scans for 5 patients with prostate treatment. Methods and Materials: The model assumes that for each patient, the organ of interest can be measured during the first few treatment days. First, the volume of each organ is delineated from each of the daily measurements and cumulated in a 3D bit-map. A tissue occupancy distribution is then constructed with the 50% isodensity representing the mean, or effective, organ volume. During the course of treatment, each voxel in the effective organ volume is assumed to move inside a local 3D neighborhood with a specific distribution function. The neighborhood and the distribution function are deduced from the positions and shapes of the organ in the first few measurements using the biomechanics model of viscoelastic body. For each voxel, the local distribution function is then convolved with the spatial dose distribution. The latter includes also the variation in dose due to daily setup error. As a result, the cumulative dose to the voxel incorporates the effects of daily setup variation and organ deformation. A ''variation adjusted'' dose volume histogram, aDVH, for the effective organ volume can then be constructed for the purpose of treatment evaluation and optimization. Up to 20 daily CT scans and daily portal images for 5 patients with prostate

  9. Evaluating Which Dose-Function Metrics Are Most Critical for Functional-Guided Radiation Therapy.

    Science.gov (United States)

    Faught, Austin M; Yamamoto, Tokihiro; Castillo, Richard; Castillo, Edward; Zhang, Jingjing; Miften, Moyed; Vinogradskiy, Yevgeniy

    2017-09-01

    Four-dimensional (4D) computed tomography (CT) ventilation imaging is increasingly being used to calculate lung ventilation and implement functional-guided radiation therapy in clinical trials. There has been little exhaustive work evaluating which dose-function metrics should be used for treatment planning and plan evaluation. The purpose of our study was to evaluate which dose-function metrics best predict for radiation pneumonitis (RP). Seventy lung cancer patients who underwent 4D CT imaging and pneumonitis grading were assessed. Pretreatment 4D CT scans of each patient were used to calculate ventilation images. We evaluated 3 types of dose-function metrics that combined the patient's 4D CT ventilation image and treatment planning dose distribution: (1) structure-based approaches; (2) image-based approaches using the dose-function histogram; and (3) nonlinear weighting schemes. Log-likelihood methods were used to generate normal tissue complication probability models predicting grade 3 or higher (ie, grade 3+) pneumonitis for all dose-function schemes. The area under the curve (AUC) was used to assess the predictive power of the models. All techniques were compared with normal tissue complication probability models based on traditional, total lung dose metrics. The most predictive models were structure-based approaches that focused on the volume of functional lung receiving ≥20 Gy (AUC, 0.70). Probabilities of grade 3+ RP of 20% and 10% correspond to V20 (percentage of volume receiving ≥20 Gy) to the functional subvolumes of 26.8% and 9.3%, respectively. Imaging-based analysis with the dose-function histogram and nonlinear weighted ventilation values yielded AUCs of 0.66 and 0.67, respectively, when we evaluated the percentage of functionality receiving ≥20 Gy. All dose-function metrics outperformed the traditional dose metrics (mean lung dose, AUC of 0.55). A full range of dose-function metrics and functional thresholds was examined. The

  10. Dose-volume effects in the rat cervical spinal cord after proton irradiation

    NARCIS (Netherlands)

    Bijl, HP; van Luijk, P; Coppes, RP; Schippers, JM; Konings, AWT; van der Kogel, AJ

    2002-01-01

    Purpose: To estimate dose-volume effects in the rat cervical spinal cord with protons. Methods and Materials: Wistar rats were irradiated on the cervical spinal cord with a single fraction of unmodulated protons (150-190 MeV) using the shoot through method, which employs the plateau of the

  11. A Nomogram for Calculation of Maximum Recommended Dose by Volume of Local Anesthetic in Pediatric Dentistry.

    Science.gov (United States)

    Williams, David; Splaver, Theodore; Walker, Jason

    2017-03-15

    Calculation of maximum recommended doses for local anesthetic agents and added vasopressors is complex and error-prone with potentially fatal consequences. The purpose of this investigation was to develop a nomogram to calculate the maximum recommended doses, expressed as volumes (number of cartridges or ml) of local anesthetic for healthy U.S. pediatric dental patients based on body weight, and test its accuracy and reproducibility. Standard mathematical techniques were used to draft the nomogram. Validation was performed using simulated patient data, and Bland-Altman analysis was used to evaluate the accuracy and repeatability of the nomogram. The nomogram was found to have a bias of 0.01 ml, with limits of agreement -0.04ml to 0.06ml and, thus, was considered to be within an acceptable range for clinical use. Our nomogram rapidly calculated the maximum recommended doses by volume of local anesthetic agents in common use to a high degree of accuracy and repeatability.

  12. Volume dose ratios relevant for alanine dosimetry in small, 6 MV photon beams

    DEFF Research Database (Denmark)

    Cronholm, Rickard O.; Andersen, Claus Erik; Behrens, Claus F.

    2012-01-01

    therapy). To this end, we here present the results of a Monte Carlo simulation study with DOSRZnrc that investigated the influence of field and detector size for small 6 MV photon beams. The study focusses on doses averaged over the volume of the detector rather than point doses.The ratio of volume...... averaged doses to water (D¯W) and alanine (D¯det) was found to be approximately 1.025 for most situations studied, and a constant ratio is likely to be representative for many applications in radiation therapy. However, D¯W/D¯det was found to be as low as 0.9908 ± 0.0037 in situations where one might...... expect significant deviations from charged particle equilibrium (i.e. at shallow depths and when the field size was smaller than the range of the secondary electrons). These effects therefore need consideration when finite-size alanine dosimeters are used under such conditions....

  13. How to understand the radiation effects of small dose - some critical comments on ICRP recommendations

    International Nuclear Information System (INIS)

    Matsuura, T.

    1997-01-01

    The widespread feeling of 'radiophobia' by the general public has its basis on the ICRP's 'linear no-threshold' hypothesis in dose-response relationship for low dose radiation from the standpoint of radiation protection. Although this common feeling served as a merit for constructing the 'safety culture' of society, it has now become a large obstacle for the development of peaceful uses of nuclear technology as a demerit. Recently many data have been accumulated for the radiation effects of low dose, both epidemiologically and experimentally. Although in general it is very difficult to obtain clear evidence of presence or absence of threshold, it seems to be true that the risk by radiation exposure at low level (the definition of which is below 0.2 Gy) is not so large as that of extrapolation from the high or medium dose range. In fact, many data suggest that some quite different mechanisms are working in low dose from high dose, such as 'adaptive response', and a new concept, 'radiation hormesis', has emerged, that the low level radiation is not only quite harmless but is rather necessary for living cells or beneficial for human health. In this paper, some critical comments on ICRP recommendations are given as a personal view by the author. These include: (1) a question of exact assessment of exposed dose by A-bomb survivors used for the epidemiological data, which are regarded to be the most authentic and important; (2) a brief summary of effects at the natural radiation level, including the high background area data; (3) the importance of dose rate effect, which reflects the living matter's repairability from radiation injury, and (4) the proposal of new paradigm by adopting the reasonable 'de minimis' level (below which there is no harm) both for low dose and at low dose rate. A simple mathematical analysis for representative data of dose rate effect was shown as an appendix

  14. Dose-volume correlation in radiation-related late small-bowel complication

    International Nuclear Information System (INIS)

    Letschert, J.G.J.; Lebesque, J.V.; Boer, R.W. de; hart, A.A.M.; Barteling, H.

    1990-01-01

    The effects of the volume of irradiated small bowel on late small-bowel tolerance was studied, taking into account the equivalent total dose ant type of pre-irradiation surgical procedure. A method was developed to estimate small-bowel volumes in the high-bowel volumes were measured for three-field and AP-PA pelvic treatments (165 cm 3 and 400 cm 3 , respectively), extended AP-PA treatment of para-aortic and iliac nodes (1000 cm 3 ). In a retrospective study of 111 patientst irradiated after surgery for rectal or recto-sigmoid cancer to a dose of 45-50 Gy in 5 weeks, extended AP-PA pelvic treatment (n = 27) resulted in a high incidence of severe small-bowel complications (37%), whereas for limited (three-field) pelvic treatment (n = 84) the complication rate was 6%. These complication data together with data from the literature on postoperative radiation-related small-bowel complications were analysed using the maximum likelihood method to fit the data to the logistic form of the dose-response relation, taking the volume effect into account by a power law. The analysis indicated that the incidence of radiation-related small-bowel compllications was higher after rectal surgery than after other types of surgery, which might be explained by the development of more adhesions. For both types of surgery a volume exponent of the power-law of 0.26 ± 0.05 was established. This means that if the small-bowel volume is increased by a factor of 2, the total dose has to be reduced by 17% for the same incidence of small-bowel complications. (author). 45 refs.; 6 figs.; 4 tabs

  15. SU-E-T-346: Effect of Jaw Position On Dose to Critical Structures in 3-D Conformal Radiotherapy Treatment of Pancreatic Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Paudel, N; Han, E; Liang, X; Morrill, S; Zhang, X; Hardee, M; Penagaricano, J; Ratanatharathorn, V [Vaneerat, University of Arkansas for Medical Sciences, Little Rock, AR (United States)

    2015-06-15

    Purpose: Three-dimensional conformal therapy remains a valid and widely used modality for pancreatic radiotherapy treatment. It usually meets dose constraints on critical structures. However, careful positioning of collimation jaws can reduce dose to the critical structures. Here we investigate the dosimetric effect of jaw position in MLC-based 3-D conformal treatment planning on critical structures. Methods: We retrospectively selected seven pancreatic cancer patients treated with 3-D conformal radiotherapy. We started with treatment plans (Varian Truebeam LINAC, Eclipse TPS, AAA, 18MV) having both x and y jaws aligned with the farthest extent of the block outline (8mm around PTV). Then we subsequently moved either both x-jaws or all x and y jaws outwards upto 3 cm in 1 cm increments and investigated their effect on average and maximum dose to neighboring critical structures keeping the same coverage to treatment volume. Results: Lateral displacement of both x-jaws by 1cm each increased kidney and spleen mean dose by as much as 1.7% and 1.3% respectively and superior inferior displacement increased liver, right kidney, stomach and spleen dose by as much as 2.1%, 2%, 5.2% and 1.6% respectively. Displacement of all x and y-jaws away by 1cm increased the mean dose to liver, right kidney, left kidney, bowels, cord, stomach and spleen by as much as 4.9%, 5.9%, 2.1%, 2.8%, 7.4%, 10.4% and 4.2% respectively. Percentage increase in mean dose due to 2 and 3cm jaw displacement increased almost linearly with the displaced distance. Changes in maximum dose were much smaller (mostly negligible) than the changes in mean dose. Conclusion: Collimation jaw position affects dose mostly to critical structures adjacent to it. Though treatment plans with MLCs conforming the block margin usually meet dose constraints to critical structures, keeping jaws all the way in, to the edge of the block reduces dose to the critical structures during radiation treatment.

  16. The dose-volume constraint satisfaction problem for inverse treatment planning with field segments

    International Nuclear Information System (INIS)

    Michalski, Darek; Xiao, Ying; Censor, Yair; Galvin, James M

    2004-01-01

    The prescribed goals of radiation treatment planning are often expressed in terms of dose-volume constraints. We present a novel formulation of a dose-volume constraint satisfaction search for the discretized radiation therapy model. This approach does not rely on any explicit cost function. Inverse treatment planning uses the aperture-based approach with predefined, according to geometric rules, segmental fields. The solver utilizes the simultaneous version of the cyclic subgradient projection algorithm. This is a deterministic iterative method designed for solving the convex feasibility problems. A prescription is expressed with the set of inequalities imposed on the dose at the voxel resolution. Additional constraint functions control the compliance with selected points of the expected cumulative dose-volume histograms. The performance of this method is tested on prostate and head-and-neck cases. The relationships with other models and algorithms of similar conceptual origin are discussed. The demonstrated advantages of the method are: the equivalence of the algorithmic and prescription parameters, the intuitive setup of free parameters, and the improved speed of the method as compared to similar iterative as well as other techniques. The technique reported here will deliver approximate solutions for inconsistent prescriptions

  17. SU-F-T-378: Evaluation of Dose-Volume Variability and Parameters Between Prostate IMRT and VMAT Plans

    Energy Technology Data Exchange (ETDEWEB)

    Chow, J [Princess Margaret Cancer Centre, Toronto, ON (Canada); Jiang, R [Grand River Regional Cancer Centre, Kitchener, ON (Canada); Kiciak, A [University of Waterloo, Waterloo, ON (Canada)

    2016-06-15

    Purpose: This study compared the rectal dose-volume consistency, equivalent uniform dose (EUD) and normal tissue complication probability (NTCP) in prostate intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). Methods: For forty prostate IMRT and fifty VMAT patients treated using the same dose prescription (78 Gy/39 fraction) and dose-volume criteria in inverse planning optimization, the rectal EUD and NTCP were calculated for each patient. The rectal dose-volume consistency, showing the variability of dose-volume histogram (DVH) among patients, was defined and calculated based on the deviation between the mean and corresponding rectal DVH. Results: From both the prostate IMRT and VMAT plans, the rectal EUD and NTCP were found decreasing with the rectal volume. The decrease rates for the IMRT plans (EUD = 0.47 × 10{sup −3} Gy cm{sup −3} and NTCP = 3.94 × 10{sup −2} % cm{sup −3}) were higher than those for the VMAT (EUD = 0.28 × 10{sup −3} Gy cm{sup −3} and NTCP = 2.61 × 10{sup −2} % cm{sup −3}). In addition, the dependences of the rectal EUD and NTCP on the dose-volume consistency were found very similar between the prostate IMRT and VMAT plans. This shows that both delivery techniques have similar variations of the rectal EUD and NTCP on the dose-volume consistency. Conclusion: Dependences of the dose-volume consistency on the rectal EUD and NTCP were compared between the prostate IMRT and VMAT plans. It is concluded that both rectal EUD and NTCP decreased with an increase of the rectal volume. The variation rates of the rectal EUD and NTCP on the rectal volume were higher for the IMRT plans than VMAT. However, variations of the rectal dose-volume consistency on the rectal EUD and NTCP were found not significant for both delivery techniques.

  18. Ipsilateral lung dose volume parameters predict radiation pneumonitis in addition to classical dose volume parameters in locally advanced NSCLC treated with combined modality therapy

    Directory of Open Access Journals (Sweden)

    Sushma Agrawal

    2014-01-01

    Full Text Available Purpose: The purpose was to determine the correlation of clinical factors and lung dose volume parameters with significant radiation pneumonitis (RP in non-small cell lung cancer patients treated with combined modality therapy. Materials and Methods: Between January 2008 and December 2010, 52 patients of non-small cell lung cancer were treated with combined modality therapy with radical intent. Radiation pneumonitis was correlated with ipsilateral (V 20 ipsi, V 5 ipsi and MLD ipsi and whole lung (V 20 , V 5 , and MLD dose volume parameters. Clinical factors like pulmonary function tests (PFT, site of tumor, planning target volume, and type of treatment were also correlated with incidence of significant pneumonitis. Results: Out of 52 patients, 35.3% developed grade 2 or more pneumonitis. On univariate analysis, factors significantly correlating with radiation pneumonitis were V 5 (P = 0.002, V 5 ipsi (P = 0.000, V 20 (P = 0.019, V 20 ipsi (P = 0.004, MLD (P = 0.008 and MLD ipsi (P = 0.008. On multivariate analysis, V 5 ipsi was retained as the most significant factor. Concurrent chemoradiation caused significantly more RP than neoadjuvant chemoradiation (P = 0.004. A cutoff of 65% for V 5 ipsi had a sensitivity of 65% and a specificity of 91%. Conclusion: The correlation between pneumonitis and dosimetric constraints has been validated. Adding ipsilateral V 20 , V 5 , and MLD to the classical total lung constraints identifies patients likely to develop pulmonary toxicity in patients undergoing chemoradiation.

  19. Gastrointestinal dose-histogram effects in the context of dose-volume-constrained prostate radiation therapy: analysis of data from the RADAR prostate radiation therapy trial.

    Science.gov (United States)

    Ebert, Martin A; Foo, Kerwyn; Haworth, Annette; Gulliford, Sarah L; Kennedy, Angel; Joseph, David J; Denham, James W

    2015-03-01

    To use a high-quality multicenter trial dataset to determine dose-volume effects for gastrointestinal (GI) toxicity following radiation therapy for prostate carcinoma. Influential dose-volume histogram regions were to be determined as functions of dose, anatomical location, toxicity, and clinical endpoint. Planning datasets for 754 participants in the TROG 03.04 RADAR trial were available, with Late Effects of Normal Tissues (LENT) Subjective, Objective, Management, and Analytic (SOMA) toxicity assessment to a median of 72 months. A rank sum method was used to define dose-volume cut-points as near-continuous functions of dose to 3 GI anatomical regions, together with a comprehensive assessment of significance. Univariate and multivariate ordinal regression was used to assess the importance of cut-points at each dose. Dose ranges providing significant cut-points tended to be consistent with those showing significant univariate regression odds-ratios (representing the probability of a unitary increase in toxicity grade per percent relative volume). Ranges of significant cut-points for rectal bleeding validated previously published results. Separation of the lower GI anatomy into complete anorectum, rectum, and anal canal showed the impact of mid-low doses to the anal canal on urgency and tenesmus, completeness of evacuation and stool frequency, and mid-high doses to the anorectum on bleeding and stool frequency. Derived multivariate models emphasized the importance of the high-dose region of the anorectum and rectum for rectal bleeding and mid- to low-dose regions for diarrhea and urgency and tenesmus, and low-to-mid doses to the anal canal for stool frequency, diarrhea, evacuation, and bleeding. Results confirm anatomical dependence of specific GI toxicities. They provide an atlas summarizing dose-histogram effects and derived constraints as functions of anatomical region, dose, toxicity, and endpoint for informing future radiation therapy planning. Crown Copyright

  20. Nuclear criticality experiments from 1943 to 1978: an annotated bibliography. Volume 1. Main listing

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, B.L.; Wilcox, T.P.; Hampel, V.E.

    1979-04-24

    The bibliography contains 1067 citations from the literature of critical and near-critical nuclear experiments. It provides an up-to-date index to reports containing useful data for many types of criticality studies. Most of the reports can provide specifications for relatively simple critical configurations necessary for validating nuclear constants and calculational techniques. The reports of more than 1143 experimentors at 38 international facilities since 1943 are cross-referenced. The collection contains the prototypes of many different designs of nuclear reactors and studies performed to insure the safe use of fissile materials in chemical processing plants, storage facilities, and transportation containers. The bibliography has three volumes. Volume 1 contains the main listing of citations with abstracts. Volume 2 is a set of indexes organized by report number, publication date, experimental facility, and author name. Volume 3 provides a subject index, concorded on the significant keyphrases derived from titles, and an index of keyterms derived from titles, and an index of keyterms extracted from titles and abstracts. The bibliography was printed by computer as a selection from a computerized system at Lawrence Livermore Laboratory contaning information and data on criticality experiments.

  1. Calculation of the ingestion critical dose rate for the Goiania radioactive waste repository

    International Nuclear Information System (INIS)

    Passos, E.M. dos; Martin Alves, A.S. De

    1994-01-01

    The calculation results of the critical distance for the ingestion dose rate due to a hypothetical Cs-137 release from the Abadia de Goias repository are shown. The work is based on the pathway repository-aquifer-well food chain. The calculations were based upon analytical models for the migration of radioisotopes through the aquifer and for its transfer from well water to food. (author)

  2. Critical groups vs. representative person: dose calculations due to predicted releases from USEXA

    International Nuclear Information System (INIS)

    Ferreira, N.L.D.; Rochedo, E.R.R.; Mazzilli, B.P.

    2013-01-01

    The critical group cf Centro Experimental Aramar (CEA) site was previously defined based 00 the effluents releases to the environment resulting from the facilities already operational at CEA. In this work, effective doses are calculated to members of the critical group considering the predicted potential uranium releases from the Uranium Hexafluoride Production Plant (USEXA). Basically, this work studies the behavior of the resulting doses related to the type of habit data used in the analysis and two distinct situations are considered: (a) the utilization of average values obtained from official institutions (IBGE, IEA-SP, CNEN, IAEA) and from the literature; and (b) the utilization of the 95 tb percentile of the values derived from distributions fit to the obtained habit data. The first option corresponds to the way that data was used for the definition of the critical group of CEA done in former assessments, while the second one corresponds to the use of data in deterministic assessments, as recommended by ICRP to estimate doses to the so--called 'representative person' . (author)

  3. Critical groups vs. representative person: dose calculations due to predicted releases from USEXA

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, N.L.D., E-mail: nelson.luiz@ctmsp.mar.mil.br [Centro Tecnologico da Marinha (CTM/SP), Sao Paulo, SP (Brazil); Rochedo, E.R.R., E-mail: elainerochedo@gmail.com [Instituto de Radiprotecao e Dosimetria (lRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Mazzilli, B.P., E-mail: mazzilli@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    The critical group cf Centro Experimental Aramar (CEA) site was previously defined based 00 the effluents releases to the environment resulting from the facilities already operational at CEA. In this work, effective doses are calculated to members of the critical group considering the predicted potential uranium releases from the Uranium Hexafluoride Production Plant (USEXA). Basically, this work studies the behavior of the resulting doses related to the type of habit data used in the analysis and two distinct situations are considered: (a) the utilization of average values obtained from official institutions (IBGE, IEA-SP, CNEN, IAEA) and from the literature; and (b) the utilization of the 95{sup tb} percentile of the values derived from distributions fit to the obtained habit data. The first option corresponds to the way that data was used for the definition of the critical group of CEA done in former assessments, while the second one corresponds to the use of data in deterministic assessments, as recommended by ICRP to estimate doses to the so--called 'representative person' . (author)

  4. Radiation dose reduction: comparative assessment of publication volume between interventional and diagnostic radiology.

    Science.gov (United States)

    Hansmann, Jan; Henzler, Thomas; Gaba, Ron C; Morelli, John N

    2017-01-01

    We aimed to quantify and compare awareness regarding radiation dose reduction within the interventional radiology and diagnostic radiology communities. Abstracts accepted to the annual meetings of the Society of Interventional Radiology (SIR), the Cardiovascular and Interventional Radiological Society of Europe (CIRSE), the Radiological Society of North America (RSNA), and the European Congress of Radiology (ECR) between 2005 and 2015 were analyzed using the search terms "interventional/computed tomography" and "radiation dose/radiation dose reduction." A PubMed query using the above-mentioned search terms for the years of 2005-2015 was performed. Between 2005 and 2015, a total of 14 520 abstracts (mean, 660±297 abstracts) and 80 614 abstracts (mean, 3664±1025 abstracts) were presented at interventional and diagnostic radiology meetings, respectively. Significantly fewer abstracts related to radiation dose were presented at the interventional radiology meetings compared with the diagnostic radiology meetings (162 abstracts [1% of total] vs. 2706 [3% of total]; P radiology abstracts (range, 6-27) and 246±105 diagnostic radiology abstracts (range, 112-389) pertaining to radiation dose were presented at each meeting. The PubMed query revealed an average of 124±39 publications (range, 79-187) and 1205±307 publications (range, 829-1672) related to interventional and diagnostic radiology dose reduction per year, respectively (P radiology community over the past 10 years has not mirrored the increased volume seen within diagnostic radiology, suggesting that increased education and discussion about this topic may be warranted.

  5. Effects of radiation dose reduction in Volume Perfusion CT imaging of acute ischemic stroke

    International Nuclear Information System (INIS)

    Othman, Ahmed E.; Brockmann, Carolin; Afat, Saif; Pjontek, Rastislav; Nikobashman, Omid; Brockmann, Marc A.; Wiesmann, Martin; Yang, Zepa; Kim, Changwon; Kim, Jong Hyo

    2015-01-01

    To examine the influence of radiation dose reduction on image quality and sensitivity of Volume Perfusion CT (VPCT) maps regarding the detection of ischemic brain lesions. VPCT data of 20 patients with suspected ischemic stroke acquired at 80 kV and 180 mAs were included. Using realistic reduced-dose simulation, low-dose VPCT datasets with 144 mAs, 108 mAs, 72 mAs and 36 mAs (80 %, 60 %, 40 % and 20 % of the original levels) were generated, resulting in a total of 100 datasets. Perfusion maps were created and signal-to-noise-ratio (SNR) measurements were performed. Qualitative analyses were conducted by two blinded readers, who also assessed the presence/absence of ischemic lesions and scored CBV and CBF maps using a modified ASPECTS-score. SNR of all low-dose datasets were significantly lower than those of the original datasets (p <.05). All datasets down to 72 mAs (40 %) yielded sufficient image quality and high sensitivity with excellent inter-observer-agreements, whereas 36 mAs datasets (20 %) yielded poor image quality in 15 % of the cases with lower sensitivity and inter-observer-agreements. Low-dose VPCT using decreased tube currents down to 72 mAs (40 % of original radiation dose) produces sufficient perfusion maps for the detection of ischemic brain lesions. (orig.)

  6. Effects of radiation dose reduction in Volume Perfusion CT imaging of acute ischemic stroke

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Ahmed E. [RWTH Aachen University, Department of Diagnostic and Interventional Neuroradiology, Aachen (Germany); Eberhard Karls University Tuebingen, University Hospital Tuebingen, Department for Diagnostic and Interventional Radiology, Tuebingen (Germany); Brockmann, Carolin; Afat, Saif; Pjontek, Rastislav; Nikobashman, Omid; Brockmann, Marc A.; Wiesmann, Martin [RWTH Aachen University, Department of Diagnostic and Interventional Neuroradiology, Aachen (Germany); Yang, Zepa; Kim, Changwon [Seoul National University, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Suwon (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Kim, Jong Hyo [Seoul National University, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Suwon (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon (Korea, Republic of)

    2015-12-15

    To examine the influence of radiation dose reduction on image quality and sensitivity of Volume Perfusion CT (VPCT) maps regarding the detection of ischemic brain lesions. VPCT data of 20 patients with suspected ischemic stroke acquired at 80 kV and 180 mAs were included. Using realistic reduced-dose simulation, low-dose VPCT datasets with 144 mAs, 108 mAs, 72 mAs and 36 mAs (80 %, 60 %, 40 % and 20 % of the original levels) were generated, resulting in a total of 100 datasets. Perfusion maps were created and signal-to-noise-ratio (SNR) measurements were performed. Qualitative analyses were conducted by two blinded readers, who also assessed the presence/absence of ischemic lesions and scored CBV and CBF maps using a modified ASPECTS-score. SNR of all low-dose datasets were significantly lower than those of the original datasets (p <.05). All datasets down to 72 mAs (40 %) yielded sufficient image quality and high sensitivity with excellent inter-observer-agreements, whereas 36 mAs datasets (20 %) yielded poor image quality in 15 % of the cases with lower sensitivity and inter-observer-agreements. Low-dose VPCT using decreased tube currents down to 72 mAs (40 % of original radiation dose) produces sufficient perfusion maps for the detection of ischemic brain lesions. (orig.)

  7. Dose and volume effects of gastrointestinal toxicity during neoadjuvant IMRT for rectal cancer

    DEFF Research Database (Denmark)

    Appelt, A. L.; Vogelius, I. R.; Jakobsen, Anders

    2015-01-01

    , such as intensity modulated radiotherapy (IMRT), can reduce dose delivered to the bowel, potentially limiting acute GI toxicity. Previous studies have reported dose-volume relationships for acute GI toxicity for patients treated with 3D conformal techniques (3D-CRT), but few have examined patients treated with IMRT......Purpose/Objective: Preoperative chemoradiotherapy for rectal cancer reduces the risk of local recurrence, but also induces gastrointestinal (GI) toxicity. Acute GI toxicity might, in addition to the discomfort caused to patients, threaten treatment compliance. Modern radiotherapy techniques....... Materials and Methods: We explored dose metrics correlating with acute diarrhea and chemotherapy compliance for a single-institution cohort of rectal cancer patients (n=115) treated with IMRT. Acute diarrhea during treatment was scored prospectively by trained RT nurses (CTCAE v3.0). The highest toxicity...

  8. Data base on dose reduction research projects for nuclear power plants: Volume 3

    Energy Technology Data Exchange (ETDEWEB)

    Khan, T.A.; Baum, J.W.

    1989-05-01

    This is the third volume in a series of reports that provide information on dose-reduction research and health physics technology for nuclear power plants. The information is taken from data base maintained by Brookhaven National Laboratory's ALARA Center for the Nuclear Regulatory Commission. This report presents information on 80 new projects, covering a wide area of activities. Projects on steam generator degradation, decontamination, robotics, improvement in reactor materials, and inspection techniques, among others, are described in the research section. The section on health physics technology includes some simple and very cost-effective projects to reduce radiation exposures. Collective dose data from the United States and other countries are also presented. In the conclusion, we suggest that although new advanced reactor design technology will eventually reduce radiation exposures at nuclear power plants to levels below serious concern, in the interim an aggressive approach to dose reduction remains necessary. 20 refs.

  9. An improved distance-to-dose correlation for predicting bladder and rectum dose-volumes in knowledge-based VMAT planning for prostate cancer

    Science.gov (United States)

    Wall, Phillip D. H.; Carver, Robert L.; Fontenot, Jonas D.

    2018-01-01

    The overlap volume histogram (OVH) is an anatomical metric commonly used to quantify the geometric relationship between an organ at risk (OAR) and target volume when predicting expected dose-volumes in knowledge-based planning (KBP). This work investigated the influence of additional variables contributing to variations in the assumed linear DVH-OVH correlation for the bladder and rectum in VMAT plans of prostate patients, with the goal of increasing prediction accuracy and achievability of knowledge-based planning methods. VMAT plans were retrospectively generated for 124 prostate patients using multi-criteria optimization. DVHs quantified patient dosimetric data while OVHs quantified patient anatomical information. The DVH-OVH correlations were calculated for fractional bladder and rectum volumes of 30, 50, 65, and 80%. Correlations between potential influencing factors and dose were quantified using the Pearson product-moment correlation coefficient (R). Factors analyzed included the derivative of the OVH, prescribed dose, PTV volume, bladder volume, rectum volume, and in-field OAR volume. Out of the selected factors, only the in-field bladder volume (mean R  =  0.86) showed a strong correlation with bladder doses. Similarly, only the in-field rectal volume (mean R  =  0.76) showed a strong correlation with rectal doses. Therefore, an OVH formalism accounting for in-field OAR volumes was developed to determine the extent to which it improved the DVH-OVH correlation. Including the in-field factor improved the DVH-OVH correlation, with the mean R values over the fractional volumes studied improving from  -0.79 to  -0.85 and  -0.82 to  -0.86 for the bladder and rectum, respectively. A re-planning study was performed on 31 randomly selected database patients to verify the increased accuracy of KBP dose predictions by accounting for bladder and rectum volume within treatment fields. The in-field OVH led to significantly more precise

  10. Lung and heart dose volume analyses with CT simulator in tangential field irradiation of breast cancer

    International Nuclear Information System (INIS)

    Das, Indra J.; Cheng, Elizabeth C.; Fowble, Barbara

    1997-01-01

    Objective: Radiation pneumonitis and cardiac effects are directly related to the irradiated lung and heart volumes in the treatment fields. The central lung distance (CLD) from a tangential breast radiograph is shown to be a significant indicator of ipsilateral irradiated lung volume based on empirically derived functions which accuracy depends on the actual measured volume in treatment position. A simple and accurate linear relationship with CLD and retrospective analysis of the pattern of dose volume of lung and heart is presented with actual volume data from a CT simulator in the treatment of breast cancer. Materials and Methods: The heart and lung volumes in the tangential treatment fields were analyzed in 45 consecutive (22 left and 23 right breast) patients referred for CT simulation of the cone down treatment. All patients in this study were immobilized and placed on an inclined breast board in actual treatment setup. Both arms were stretched over head uniformly to avoid collision with the scanner aperture. Radiopaque marks were placed on the medial and lateral borders of the tangential fields. All patients were scanned in spiral mode with slice width and thickness of 3 mm each, respectively. The lung and heart structures as well as irradiated areas were delineated on each slice and respective volumes were accurately measured. The treatment beam parameters were recorded and the digitally reconstructed radiographs (DRRs) were generated for the CLD and analysis. Results: Table 1 shows the volume statistics of patients in this study. There is a large variation in the lung and heart volumes among patients. Due to differences in the shape of right and left lungs the percent irradiated volume (PIV) are different. The PIV data have shown to correlate with CLD with 2nd and 3rd degree polynomials; however, in this study a simple straight line regression is used to provide better confidence than the higher order polynomial. The regression lines for the left and right

  11. The sensitivity of calculated doses to critical assumptions for the offsite consequences of nuclear power reactor accidents

    International Nuclear Information System (INIS)

    Moeller, M.P.; Scherpelz, R.I.; Desrosiers, A.E.

    1982-01-01

    This work analyzes the sensitivity of calculated doses to critical assumptions for offsite consequences following a PWR-2 accident at a nuclear power reactor. The calculations include three radiation dose pathways: internal dose resulting from inhalation, external doses from exposure to the plume, and external doses from exposure to contaminated ground. The critical parameters are the time period of integration for internal dose commitment and the duration of residence on contaminated ground. The data indicate the calculated offsite whole body dose will vary by as much as 600% depending upon the parameters assumed. When offsite radiation doses determine the size of emergency planning zones, this uncertainty has significant effect upon the resources allocated to emergency preparedness

  12. Augmented Renal Clearance in Critical Illness: An Important Consideration in Drug Dosing

    Directory of Open Access Journals (Sweden)

    Sherif Hanafy Mahmoud

    2017-09-01

    Full Text Available Augmented renal clearance (ARC is a manifestation of enhanced renal function seen in critically ill patients. The use of regular unadjusted doses of renally eliminated drugs in patients with ARC might lead to therapy failure. The purpose of this scoping review was to provide and up-to-date summary of the available evidence pertaining to the phenomenon of ARC. A literature search of databases of available evidence in humans, with no language restriction, was conducted. Databases searched were MEDLINE (1946 to April 2017, EMBASE (1974 to April 2017 and the Cochrane Library (1999 to April 2017. A total of 57 records were included in the present review: 39 observational studies (25 prospective, 14 retrospective, 6 case reports/series and 12 conference abstracts. ARC has been reported to range from 14–80%. ARC is currently defined as an increased creatinine clearance of greater than 130 mL/min/1.73 m2 best measured by 8–24 h urine collection. Patients exhibiting ARC tend to be younger (<50 years old, of male gender, had a recent history of trauma, and had lower critical illness severity scores. Numerous studies have reported antimicrobials treatment failures when using standard dosing regimens in patients with ARC. In conclusion, ARC is an important phenomenon that might have significant impact on outcome in critically ill patients. Identifying patients at risk, using higher doses of renally eliminated drugs or use of non-renally eliminated alternatives might need to be considered in ICU patients with ARC. More research is needed to solidify dosing recommendations of various drugs in patients with ARC.

  13. The study of dose variation and change of heart volume using 4D-CT in left breast radiation therapy

    International Nuclear Information System (INIS)

    Park, Seon Mi; Cheon, Geum Seong; Heo, Gyeong Hun; Shin, Sung Pil; Kim, Kwang Seok; Kim, Chang Uk; Kim, Hoi Nam

    2013-01-01

    We investigate the results of changed heart volume and heart dose in the left breast cancer patients while considering the movements of respiration. During the months of March and May in 2012, we designated the 10 patients who had tangential irradiation with left breast cancer in the department of radiation Oncology. With acquired images of free breathing pattern through 3D and 4D CT, we had planed enough treatment filed for covered up the whole left breast. It compares the results of the exposed dose and the volume of heart by DVH (Dose Volume histogram). Although total dose was 50.4 Gy (1.8 Gy/28 fraction), reirradiated 9 Gy (1.8 Gy/5 Fraction) with PTV (Planning Target Volume) if necessary. It compares the results of heart volume and heart dose with the free breathing in 3D CT and 4D CT. It represents the maximum difference volume of heart is 40.5%. In addition, it indicated the difference volume of maximum and minimum, average are 8.8% and 27.9%, 37.4% in total absorbed dose of heart. In case of tangential irradiation (opposite beam) in left breast cancer patients, it is necessary to consider the changed heart volume by the respiration of patient and the heartbeat of patient

  14. Gastrointestinal toxicity of vorinostat: reanalysis of phase 1 study results with emphasis on dose-volume effects of pelvic radiotherapy

    International Nuclear Information System (INIS)

    Bratland, Åse; Dueland, Svein; Hollywood, Donal; Flatmark, Kjersti; Ree, Anne H

    2011-01-01

    In early-phase studies with targeted therapeutics and radiotherapy, it may be difficult to decide whether an adverse event should be considered a dose-limiting toxicity (DLT) of the investigational systemic agent, as acute normal tissue toxicity is frequently encountered with radiation alone. We have reanalyzed the toxicity data from a recently conducted phase 1 study on vorinostat, a histone deacetylase inhibitor, in combination with pelvic palliative radiotherapy, with emphasis on the dose distribution within the irradiated bowel volume to the development of DLT. Of 14 eligible patients, three individuals experienced Common Terminology Criteria of Adverse Events grade 3 gastrointestinal and related toxicities, representing a toxicity profile vorinostat has in common with radiotherapy to pelvic target volumes. For each study patient, the relative volumes of small bowel receiving radiation doses between 6 Gy and 30 Gy at 6-Gy intervals (V6-V30) were determined from the treatment-planning computed tomography scans. The single patient that experienced a DLT at the second highest dose level of vorinostat, which was determined as the maximum-tolerated dose, had V6-V30 dose-volume estimates that were considerably higher than any other study patient. This patient may have experienced an adverse radiation dose-volume effect rather than a toxic effect of the investigational drug. When reporting early-phase trial results on the tolerability of a systemic targeted therapeutic used as potential radiosensitizing agent, radiation dose-volume effects should be quantified to enable full interpretation of the study toxicity profile.

  15. Dose-volume analysis of hypothyroidism in patients irradiated to the neck

    International Nuclear Information System (INIS)

    Te, Vuong; Liu, Mitchell C.C.; Parker, William; Curtin-Savard, Arthur J.; Clark, Brenda

    1997-01-01

    Purpose: To determine if the incidence of hypothyroidism in patients who have received radiation therapy to the neck region has any relationship with the total dose to the thyroid and volume of thyroid irradiation. Methods and Materials: From 1988 to 1996, TSH levels were measured at regular intervals of every 3 to 6 months in 528 patients with head and neck cancers or lymphomas (Hodgkin and non-Hodgkin) who had received radiation therapy to the neck region. Hypothyroidism was defined by TSH of ≥ 5 (normal range: 0.5 - 4mU/L). Medical charts, radiotherapy charts, treatment planning films, dosimetry and CT scans/MRI were reviewed. Thyroid volume was determined utilizing treatment planning films and CT scans/MRI. Four hundred and six patients had normal TSH prior to radiation and sufficient information to be eligible for analysis. There were 264 (65%) male and 142 (35%) female, median age was 59 yr (range: 12 - 85). Median follow-up was 39.5 months (range: 1 - 289 months). Results: Out of the 406 eligible patients, 152 (37%) had developed hypothyroidism. The actuarial incidence of hypothyroidism at 1 yr, 3 yr and 5 yr are 9.1%, 29% and 38.5%, respectively. Analysis of volume effect and dose effect are as follows: When the radiation dose to the thyroid and the volume of thyroid irradiated are analyzed together, the group of patients who received ≥ 60Gy to half of thyroid or received ≥ 30Gy to the whole thyroid has increased risk of developing hypothyroidism as compared to those receiving <60Gy to half the thyroid or <30Gy to the whole thyroid (p=.0001). Conclusions: The actuarial incidence of hypothyroidism at 5 year in patients who had received radiation to the neck is 38.5%. Patients who received ≥ 60Gy to half the thyroid or received ≥ 30Gy to the whole thyroid are at higher risk of developing hyperthyroidism

  16. Time, dose and volume factors in interstitial brachytherapy combined with external irradiation for oral tongue carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Yorozu, Atsunori [National Tokyo Second Hospital (Japan)

    1996-04-01

    This is a retrospective analysis of 136 patients with squamous cell carcinoma of stages I and II of the oral tongue who were treated with interstitial brachytherapy alone or in combination with external irradiation between 1976 and 1991. Control of the primary lesion and the occurrence of late complications were analyzed with respect to dose, time and tumor size with the Cox hazard model. The 5-year survival rates for stages I and II were 84.5% and 75.6%. The 5-year primary control rate was 91.3% for stage I and 77.3% for stage II (p<0.05). Local control and survival rates were comparable with those of other modalities. The significant factor in local control was stage. For lesions more than 30 mm in diameter, local control was rather poor in the group given only brachytherapy compared with the group given combined therapy. After 30 Gy of external irradiation, local control was better at a brachytherapy dose >50 Gy compared with a brachytherapy dose <=50 Gy. Mucosal ulcer occurred frequently with increasing total dose and tumor volume. Bone necrosis increased significantly with increasing external irradiation dose. We suggest that external irradiation of 30 Gy followed by brachytherapy of 52 Gy is a better choice for T2 lesions >30 mm. Late complications should be reduced by using a spacer, improvements in dental and oral hygiene, and a sophisticated implant method. (author).

  17. Infarct volume predicts critical care needs in stroke patients treated with intravenous thrombolysis

    Energy Technology Data Exchange (ETDEWEB)

    Faigle, Roland; Marsh, Elisabeth B.; Llinas, Rafael H.; Urrutia, Victor C. [Johns Hopkins University School of Medicine, Department of Neurology, Baltimore, MD (United States); Wozniak, Amy W. [Johns Hopkins University, Department of Biostatistics, Bloomberg School of Public Health, Baltimore, MD (United States)

    2014-10-26

    Patients receiving intravenous thrombolysis with recombinant tissue plasminogen activator (IVT) for ischemic stroke are monitored in an intensive care unit (ICU) or a comparable unit capable of ICU interventions due to the high frequency of standardized neurological exams and vital sign checks. The present study evaluates quantitative infarct volume on early post-IVT MRI as a predictor of critical care needs and aims to identify patients who may not require resource intense monitoring. We identified 46 patients who underwent MRI within 6 h of IVT. Infarct volume was measured using semiautomated software. Logistic regression and receiver operating characteristics (ROC) analysis were used to determine factors associated with ICU needs. Infarct volume was an independent predictor of ICU need after adjusting for age, sex, race, systolic blood pressure, NIH Stroke Scale (NIHSS), and coronary artery disease (odds ratio 1.031 per cm{sup 3} increase in volume, 95 % confidence interval [CI] 1.004-1.058, p = 0.024). The ROC curve with infarct volume alone achieved an area under the curve (AUC) of 0.766 (95 % CI 0.605-0.927), while the AUC was 0.906 (95 % CI 0.814-0.998) after adjusting for race, systolic blood pressure, and NIHSS. Maximum Youden index calculations identified an optimal infarct volume cut point of 6.8 cm{sup 3} (sensitivity 75.0 %, specificity 76.7 %). Infarct volume greater than 3 cm{sup 3} predicted need for critical care interventions with 81.3 % sensitivity and 66.7 % specificity. Infarct volume may predict needs for ICU monitoring and interventions in stroke patients treated with IVT. (orig.)

  18. Lung and heart dose volume analyses with CT simulator in radiation treatment of breast cancer.

    Science.gov (United States)

    Das, I J; Cheng, E C; Freedman, G; Fowble, B

    1998-08-01

    Radiation pneumonitis and cardiac effects are directly related to the irradiated lung and heart volumes in the treatment fields. The central lung distance (CLD) from a tangential breast radiograph is shown to be a significant indicator of ipsilateral irradiated lung volume. Retrospective analysis of the pattern of dose volume of lung and heart with actual volume data from a CT simulator in the treatment of breast cancer is presented with respect to CLD. The heart and lung volumes in the tangential treatment fields were analyzed in 108 consecutive cases (52 left and 56 right breast) referred for CT simulation. All patients in this study were immobilized and placed on an inclined breast board in actual treatment setup. Both arms were stretched over head to avoid collision with the scanner aperture. Radiopaque marks were placed on the medial and lateral borders of the tangential fields. All patients were scanned in spiral mode with slice width and thickness of 3 mm each, respectively. The lung and heart structures as well as irradiated areas were delineated on each slice and respective volumes were accurately measured. The treatment beam parameters were recorded and the digitally reconstructed radiographs (DRRs) were generated for the measurement of the CLD and analysis. Using CT data the mean volume and standard deviation of left and right lungs were 1307.7+/-297.7 cm3 and 1529.6+/-298.5 cm3, respectively. The magnitude of irradiated volume in left and right lung is nearly equal for the same CLD that produces different percent irradiated volumes (PIV). The left and right PIV lungs are 8.3+/-4.7% and 6.6+/-3.7%, respectively. The PIV data have shown to correlate with CLD with second- and third-degree polynomials; however, in this study a simple straight line regression is used to provide better confidence than the higher order polynomials. The regression lines for the left and right breasts are very different based on actual CT data. The slopes of regression lines for

  19. Lung and heart dose volume analyses with CT simulator in radiation treatment of breast cancer

    International Nuclear Information System (INIS)

    Das, Indra J.; Cheng, Elizabeth C.; Freedman, Gary; Fowble, Barbara

    1998-01-01

    Purpose: Radiation pneumonitis and cardiac effects are directly related to the irradiated lung and heart volumes in the treatment fields. The central lung distance (CLD) from a tangential breast radiograph is shown to be a significant indicator of ipsilateral irradiated lung volume. Retrospective analysis of the pattern of dose volume of lung and heart with actual volume data from a CT simulator in the treatment of breast cancer is presented with respect to CLD. Methods and Materials: The heart and lung volumes in the tangential treatment fields were analyzed in 108 consecutive cases (52 left and 56 right breast) referred for CT simulation. All patients in this study were immobilized and placed on an inclined breast board in actual treatment setup. Both arms were stretched over head to avoid collision with the scanner aperture. Radiopaque marks were placed on the medial and lateral borders of the tangential fields. All patients were scanned in spiral mode with slice width and thickness of 3 mm each, respectively. The lung and heart structures as well as irradiated areas were delineated on each slice and respective volumes were accurately measured. The treatment beam parameters were recorded and the digitally reconstructed radiographs (DRRs) were generated for the measurement of the CLD and analysis. Results: Using CT data the mean volume and standard deviation of left and right lungs were 1307.7 ± 297.7 cm 3 and 1529.6 ± 298.5 cm 3 , respectively. The magnitude of irradiated volume in left and right lung is nearly equal for the same CLD that produces different percent irradiated volumes (PIV). The left and right PIV lungs are 8.3 ± 4.7% and 6.6 ± 3.7%, respectively. The PIV data have shown to correlate with CLD with second- and third-degree polynomials; however, in this study a simple straight line regression is used to provide better confidence than the higher order polynomials. The regression lines for the left and right breasts are very different based on

  20. Biosphere Dose Conversion Factors for Reasonably Maximally Exposed Individual and Average Member of Critical Group

    International Nuclear Information System (INIS)

    K. Montague

    2000-01-01

    The purpose of this calculation is to develop additional Biosphere Dose Conversion Factors (BDCFs) for a reasonably maximally exposed individual (RMEI) for the periods 10,000 years and 1,000,000 years after the repository closure. In addition, Biosphere Dose Conversion Factors for the average member of a critical group are calculated for those additional radionuclides postulated to reach the environment during the period after 10,000 years and up to 1,000,000 years. After the permanent closure of the repository, the engineered systems within the repository will eventually lose their abilities to contain radionuclide inventory, and the radionuclides will migrate through the geosphere and eventually enter the local water table moving toward inhabited areas. The primary release scenario is a groundwater well used for drinking water supply and irrigation, and this calculation takes these postulated releases and follows them through various pathways until they result in a dose to either a member of critical group or a reasonably maximally exposed individual. The pathways considered in this calculation include inhalation, ingestion, and direct exposure

  1. Temporal Evolution and Dose-Volume Histogram Predictors of Visual Acuity After Proton Beam Radiation Therapy of Uveal Melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Polishchuk, Alexei L. [Department of Radiation Oncology, University of California, San Francisco, San Francisco, California (United States); Mishra, Kavita K., E-mail: Kavita.Mishra@ucsf.edu [Department of Radiation Oncology, University of California, San Francisco, San Francisco, California (United States); Weinberg, Vivian; Daftari, Inder K. [Department of Radiation Oncology, University of California, San Francisco, San Francisco, California (United States); Nguyen, Jacqueline M.; Cole, Tia B. [Tumori Foundation, San Francisco, California (United States); Quivey, Jeanne M.; Phillips, Theodore L. [Department of Radiation Oncology, University of California, San Francisco, San Francisco, California (United States); Char, Devron H. [Tumori Foundation, San Francisco, California (United States)

    2017-01-01

    Purpose: To perform an in-depth temporal analysis of visual acuity (VA) outcomes after proton beam radiation therapy (PBRT) in a large, uniformly treated cohort of uveal melanoma (UM) patients, to determine trends in VA evolution depending on pretreatment and temporally defined posttreatment VA measurements; and to investigate the relevance of specific patient, tumor and dose-volume parameters to posttreatment vision loss. Methods and Materials: Uveal melanoma patients receiving PBRT were identified from a prospectively maintained database. Included patients (n=645) received 56 GyE in 4 fractions, had pretreatment best corrected VA (BCVA) in the affected eye of count fingers (CF) or better, with posttreatment VA assessment at specified post-PBRT time point(s). Patients were grouped according to the pretreatment BCVA into favorable (≥20/40) or unfavorable (20/50-20/400) and poor (CF) strata. Temporal analysis of BCVA changes was described, and univariate and forward stepwise multivariate logistic regression analyses were performed to identify predictors for VA loss. Results: Median VA follow-up was 53 months (range, 3-213 months). At 60-month follow up, among evaluable treated eyes with favorable pretreatment BCVA, 45% retained BCVA ≥20/40, whereas among evaluable treated eyes with initially unfavorable/poor BCVA, 21% had vision ≥20/100. Among those with a favorable initial BCVA, attaining BCVA of ≥20/40 at any posttreatment time point was associated with subsequent maintenance of excellent BCVA. Multivariate analysis identified volume of the macula receiving 28GyE (P<.0001) and optic nerve (P=.0004) as independent dose-volume histogram predictors of 48-month post-PBRT vision loss among initially favorable treated eyes. Conclusions: Approximately half of PBRT-treated UM eyes with excellent pretreatment BCVA assessed at 5 years after treatment will retain excellent long-term vision. 28GyE macula and optic nerve dose-volume histogram parameters allow for

  2. Effects of radiation dose reduction in Volume Perfusion CT imaging of acute ischemic stroke.

    Science.gov (United States)

    Othman, Ahmed E; Brockmann, Carolin; Yang, Zepa; Kim, Changwon; Afat, Saif; Pjontek, Rastislav; Nikobashman, Omid; Brockmann, Marc A; Kim, Jong Hyo; Wiesmann, Martin

    2015-12-01

    To examine the influence of radiation dose reduction on image quality and sensitivity of Volume Perfusion CT (VPCT) maps regarding the detection of ischemic brain lesions. VPCT data of 20 patients with suspected ischemic stroke acquired at 80 kV and 180 mAs were included. Using realistic reduced-dose simulation, low-dose VPCT datasets with 144 mAs, 108 mAs, 72 mAs and 36 mAs (80 %, 60 %, 40 % and 20 % of the original levels) were generated, resulting in a total of 100 datasets. Perfusion maps were created and signal-to-noise-ratio (SNR) measurements were performed. Qualitative analyses were conducted by two blinded readers, who also assessed the presence/absence of ischemic lesions and scored CBV and CBF maps using a modified ASPECTS-score. SNR of all low-dose datasets were significantly lower than those of the original datasets (p < .05). All datasets down to 72 mAs (40 %) yielded sufficient image quality and high sensitivity with excellent inter-observer-agreements, whereas 36 mAs datasets (20 %) yielded poor image quality in 15 % of the cases with lower sensitivity and inter-observer-agreements. Low-dose VPCT using decreased tube currents down to 72 mAs (40 % of original radiation dose) produces sufficient perfusion maps for the detection of ischemic brain lesions. • Perfusion CT is highly accurate for the detection of ischemic brain lesions • Perfusion CT results in high radiation exposure, therefore low-dose protocols are required • Reduction of tube current down to 72 mAs produces sufficient perfusion maps.

  3. Optimal dose and volume for postoperative radiotherapy in brain oligometastases from lung cancer: a retrospective study

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Seung Yeun; Kim, Hye Ryun; Cho, Byoung Chul; Lee, Chang Geol; Suh, Chang Ok [Yonsei Cancer Center, Yonsei University College of Medicine, Seoul (Korea, Republic of); Chang, Jong Hee [Dept. of Neurosurgery, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2017-06-15

    To evaluate intracranial control after surgical resection according to the adjuvant treatment received in order to assess the optimal radiotherapy (RT) dose and volume. Between 2003 and 2015, a total of 53 patients with brain oligometastases from non-small cell lung cancer (NSCLC) underwent metastasectomy. The patients were divided into three groups according to the adjuvant treatment received: whole brain radiotherapy (WBRT) ± boost (WBRT ± boost group, n = 26), local RT/Gamma Knife surgery (local RT group, n = 14), and the observation group (n = 13). The most commonly used dose schedule was WBRT (25 Gy in 10 fractions, equivalent dose in 2 Gy fractions [EQD2] 26.04 Gy) with tumor bed boost (15 Gy in 5 fractions, EQD2 16.25 Gy). The WBRT ± boost group showed the lowest 1-year intracranial recurrence rate of 30.4%, followed by the local RT and observation groups, at 66.7%, and 76.9%, respectively (p = 0.006). In the WBRT ± boost group, there was no significant increase in the 1-year new site recurrence rate of patients receiving a lower dose of WBRT (EQD2) <27 Gy compared to that in patients receiving a higher WBRT dose (p = 0.553). The 1-year initial tumor site recurrence rate was lower in patients receiving tumor bed dose (EQD2) of ≥42.3 Gy compared to those receiving <42.3 Gy, although the difference was not significant (p = 0.347). Adding WBRT after resection of brain oligometastases from NSCLC seems to enhance intracranial control. Furthermore, combining lower-dose WBRT with a tumor bed boost may be an attractive option.

  4. Critically safe volume vacuum pickup for use in wet or dry cleanup of radioactive enclosures

    International Nuclear Information System (INIS)

    Zeren, J.D.

    1993-01-01

    A physical compact vacuum pickup device of critically safe volume and geometric shape is provided for use in radioactive enclosures, such as a small glove box, to facilitate manual cleanup of either wet or dry radioactive material. The device is constructed and arranged so as to remain safe when filled to capacity with plutonium-239 oxide. Two fine mesh filter bags are supported on the exterior of a rigid fine mesh stainless steel cup. This assembly is sealed within, and spaced from, the interior walls of a stainless steel canister. An air inlet communicates with the interior of the canister. A modified conventional vacuum head is physically connected to, and associated with, the interior of the mesh cup. The volume of the canister, as defined by the space between the mesh cup and the interior walls of the canister, forms a critically safe volume and geometric shape for dry radioactive particles that are gathered within the canister. A critically safe liquid volume is maintained by operation of a suction terminating float valve, and/or by operation of redundant vacuum check/liquid drain valves and placement of the air inlet. 5 figures

  5. Dose-Volume Analysis of Radiation Nephropathy in Children: Preliminary Report of the Risk Consortium

    International Nuclear Information System (INIS)

    Boelling, Tobias; Ernst, Iris; Pape, Hildegard; Martini, Carmen; Ruebe, Christian; Timmermann, Beate; Fischedick, Karin; Kortmann, Rolf-Dieter; Willich, Normann

    2011-01-01

    Purpose: To characterize kidney function in children and adolescents who had undergone radiation treatment that included parts of the kidney. Methods and Materials: Patients receiving radiotherapy during childhood or adolescence were prospectively registered in Germany's Registry for the Evaluation of Side Effects after Radiation in Childhood and Adolescence (RiSK). Detailed information was recorded regarding radiation doses at the organs at risk since 2001 all over Germany. Toxicity evaluation was performed according to standardized Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria. Results: Up to May 2009, 1086 patients from 62 centers were recruited, including 126 patients (median age, 10.2 years) who underwent radiotherapy to parts of the kidneys. Maximal late toxicity (median follow-up 28.5 months in 74 patients) was characterized as Grade 0 (n = 65), 1 (n = 7) or 2 (n = 2). All patients with late effects had received potentially nephrotoxic chemotherapy. A statistically significant difference between patients with and without Grade 1 toxicity, revealing higher exposed kidney volumes in patients with toxicity, was seen for the kidney volume exposed to 20 Gy (V20; p = 0.031) and 30 Gy (V30; p = 0.003). Conclusions: Preliminary data indicate that radiation-induced kidney function impairment is rare in current pediatric multimodal treatment approaches. In the future, RiSK will be able to provide further detailed data regarding dose-volume effect relationships of radiation-associated side effects in pediatric oncology patients.

  6. A framework to measure myocardial extracellular volume fraction using dual-phase low dose CT images

    International Nuclear Information System (INIS)

    Liu, Yixun; Summers, Ronald M.; Yao, Jianhua; Liu, Songtao; Sibley, Christopher T.; Bluemke, David A.; Nacif, Marcelo S.

    2013-01-01

    Purpose: Myocardial extracellular volume fraction (ECVF) is a surrogate imaging biomarker of diffuse myocardial fibrosis, a hallmark of pathologic ventricular remodeling. Low dose cardiac CT is emerging as a promising modality to detect diffuse interstitial myocardial fibrosis due to its fast acquisition and low radiation; however, the insufficient contrast in the low dose CT images poses great challenge to measure ECVF from the image. Methods: To deal with this difficulty, the authors present a complete ECVF measurement framework including a point-guided myocardial modeling, a deformable model-based myocardium segmentation, nonrigid registration of pre- and post-CT, and ECVF calculation. Results: The proposed method was evaluated on 20 patients by two observers. Compared to the manually delineated reference segmentations, the accuracy of our segmentation in terms of true positive volume fraction (TPVF), false positive volume fraction (FPVF), and average surface distance (ASD), were 92.18% ± 3.52%, 0.31% ± 0.10%, 0.69 ± 0.14 mm, respectively. The interobserver variability measured by concordance correlation coefficient regarding TPVF, FPVF, and ASD were 0.95, 0.90, 0.94, respectively, demonstrating excellent agreement. Bland-Altman method showed 95% limits of agreement between ECVF at CT and ECVF at MR. Conclusions: The proposed framework demonstrates its efficiency, accuracy, and noninvasiveness in ECVF measurement and dramatically advances the ECVF at cardiac CT toward its clinical use

  7. Volume dose ratios relevant for alanine dosimetry in small, 6 MV photon beams

    International Nuclear Information System (INIS)

    Cronholm, Rickard O.; Andersen, Claus E.; Behrens, Claus F.; Helt-Hansen, Jakob

    2012-01-01

    The overall objective of this work is to establish alanine dosimetry for traceable measurements in clinical radiotherapy beams, in particular for non-reference situations such as small field sizes and composite beam delivery (e.g. intensity modulated radiotherapy and volumetric modulated arc therapy). To this end, we here present the results of a Monte Carlo simulation study with DOSRZnrc that investigated the influence of field and detector size for small 6 MV photon beams. The study focusses on doses averaged over the volume of the detector rather than point doses. The ratio of volume averaged doses to water (D ¯ W ) and alanine (D ¯ det ) was found to be approximately 1.025 for most situations studied, and a constant ratio is likely to be representative for many applications in radiation therapy. However, D ¯ W /D ¯ det was found to be as low as 0.9908 ± 0.0037 in situations where one might expect significant deviations from charged particle equilibrium (i.e. at shallow depths and when the field size was smaller than the range of the secondary electrons). These effects therefore need consideration when finite-size alanine dosimeters are used under such conditions.

  8. The history of critical group doses from the consumption of freshwater fish at Trawsfynydd, North Wales

    International Nuclear Information System (INIS)

    Leonard, D.R.P.

    1992-01-01

    Radionuclides discharged into the aquatic environment from Trawsfynydd power station are, as for all UK facilities, subject to statutory controls to ensure that the resulting public radiation exposure complies with nationally-accepted criteria. Environmental monitoring by MAFF has shown that near this facility the consumption of freshwater fish is radiologically the most important pathway with Cs-137 the dominant radionuclide. Information gathered from consumers over a twenty-five year period has been interpreted so as to derive doses to the public. Committed effective doses (CEDs) are presented using ICRP 1990 methodology and compared with the recommended dose limit of 1 mSv year -1 . Doses to the critical group are shown to have exceeded 1 mSv year -1 for two years but do not exceed this limit when averaged over a period of 5 years. Because of the changing habits of the consumers it is suggested that the average annual CED over the lifetime of any member of the public will not exceed 1 mSv year -1 during the operation of the station. (author)

  9. Radiation-induced changes of brain tissue after radiosurgery in patients with arteriovenous malformations: dose/volume-response relations

    Energy Technology Data Exchange (ETDEWEB)

    Levegruen, S.; Schlegel, W. [Dept. of Medical Physics, German Cancer Research Center (DKFZ), Heidelberg (Germany); Hof, H.; Debus, J. [Dept. of Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg (Germany); Essig, M. [Dept. of Radiology, German Cancer Research Center (DKFZ), Heidelberg (Germany)

    2004-12-01

    Purpose: to evaluate late radiation effects in the brain after radiosurgery of patients with cerebral arteriovenous malformations (AVMs) and to quantify dose/volume-response relations for radiation-induced changes of brain tissue identified on follow-up neuroimaging. Patients and methods: data from 73 AVM patients who had stereotactic linac radiosurgery at DKFZ (German Cancer Research Center), Heidelberg, Germany, were retrospectively analyzed. The endpoint of radiation-induced changes of brain tissue on follow-up magnetic resonance (MR) neuroimaging (i.e., edema and blood-brain-barrier breakdown [BBBB]) was evaluated. Each endpoint was further differentiated into three levels with respect to the extent of the image change (small, intermediate, and large). A previous analysis of the data found correlation of the endpoints with several dose/volume variables (DV) derived from each patient's dose distribution in the brain, including the mean dose in a volume of 20 cm{sup 3} (Dmean20) and the absolute brain volume (including the AVM target) receiving a dose of at least 12 Gy (V12). To quantify dose/volume-response relations, patients were ranked according to DV (i.e., Dmean20 and V12) and classified into four groups of equal size. For each group, the actuarial rates of developing the considered endpoints within 2.5 years after radiosurgery were determined from Kaplan-Meier estimates. The dose/volume-response curves were fitted with a sigmoid-shape logistic function and characterized by DV{sub 50}, the dose for a 50% incidence, and the slope parameter k. Results: dose/volume-response relations, based on two alternative, but correlated, dose distribution variables that are a function of both dose and volume, were observed for radiation-induced changes of brain tissue. DV{sub 50} values of fitted dose/volume-response curves for tissue changes of large extent (e.g., V12{sub 50} = 22.0 {+-} 2.6 cm{sup 3} and Dmean20{sub 50} = 17.8 {+-} 2.0 Gy for the combined endpoint

  10. Quantifying the Impact of Immediate Reconstruction in Postmastectomy Radiation: A Large, Dose-Volume Histogram-Based Analysis

    International Nuclear Information System (INIS)

    Ohri, Nisha; Cordeiro, Peter G.; Keam, Jennifer; Ballangrud, Ase; Shi Weiji; Zhang Zhigang; Nerbun, Claire T.; Woch, Katherine M.; Stein, Nicholas F.; Zhou Ying; McCormick, Beryl; Powell, Simon N.; Ho, Alice Y.

    2012-01-01

    Purpose: To assess the impact of immediate breast reconstruction on postmastectomy radiation (PMRT) using dose-volume histogram (DVH) data. Methods and Materials: Two hundred forty-seven women underwent PMRT at our center, 196 with implant reconstruction and 51 without reconstruction. Patients with reconstruction were treated with tangential photons, and patients without reconstruction were treated with en-face electron fields and customized bolus. Twenty percent of patients received internal mammary node (IMN) treatment. The DVH data were compared between groups. Ipsilateral lung parameters included V20 (% volume receiving 20 Gy), V40 (% volume receiving 40 Gy), mean dose, and maximum dose. Heart parameters included V25 (% volume receiving 25 Gy), mean dose, and maximum dose. IMN coverage was assessed when applicable. Chest wall coverage was assessed in patients with reconstruction. Propensity-matched analysis adjusted for potential confounders of laterality and IMN treatment. Results: Reconstruction was associated with lower lung V20, mean dose, and maximum dose compared with no reconstruction (all P 98%). IMN coverage was superior in patients with reconstruction (D95 >92.0 vs 75.7%, P .05). Among IMN-treated patients, only lower lung V20 in those without reconstruction persisted (P=.022), and mean and maximum heart doses were higher than in patients without reconstruction (P=.006, P=.015, respectively). Conclusions: Implant reconstruction does not compromise the technical quality of PMRT when the IMNs are untreated. Treatment technique, not reconstruction, is the primary determinant of target coverage and normal tissue doses.

  11. Total-dose radiation effects data for semiconductor devices. 1985 supplement. Volume 2, part A

    International Nuclear Information System (INIS)

    Martin, K.E.; Gauthier, M.K.; Coss, J.R.; Dantas, A.R.V.; Price, W.E.

    1986-05-01

    Steady-state, total-dose radiation test data, are provided in graphic format for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. This volume provides data on integrated circuits. The data are presented in graphic, tabular, and/or narrative format, depending on the complexity of the integrated circuit. Most tests were done using the JPL or Boeing electron accelerator (Dynamitron) which provides a steady-state 2.5 MeV electron beam. However, some radiation exposures were made with a cobalt-60 gamma ray source, the results of which should be regarded as only an approximate measure of the radiation damage that would be incurred by an equivalent electron dose

  12. Personnel neutron dose assessment upgrade: Volume 2, Field neutron spectrometer for health physics applications

    International Nuclear Information System (INIS)

    Brackenbush, L.W.; Reece, W.D.; Miller, S.D.

    1988-07-01

    Both the (ICRP) and the (NCPR) have recommended an increase in neutron quality factors and the adoption of effective dose equivalent methods. The series of reports entitled Personnel Neutron Dose Assessment Upgrade (PNL-6620) addresses these changes. Volume 1 in this series of reports (Personnel Neutron Dosimetry Assessment) provided guidance on the characteristics, use, and calibration of personnel neutron dosimeters in order to meet the new recommendations. This report, Volume 2: Field Neutron Spectrometer for Health Physics Applications describes the development of a portable field spectrometer which can be set up for use in a few minutes by a single person. The field spectrometer described herein represents a significant advance in improving the accuracy of neutron dose assessment. It permits an immediate analysis of the energy spectral distribution associated with the radiation from which neutron quality factor can be determined. It is now possible to depart from the use of maximum Q by determining and realistically applying a lower Q based on spectral data. The field spectrometer is made up of two modules: a detector module with built-in electronics and an analysis module with a IBM PC/reg sign/-compatible computer to control the data acquisition and analysis of data in the field. The unit is simple enough to allow the operator to perform spectral measurements with minimal training. The instrument is intended for use in steady-state radiation fields with neutrons energies covering the fission spectrum range. The prototype field spectrometer has been field tested in plutonium processing facilities, and has been proven to operate satisfactorily. The prototype field spectrometer uses a 3 He proportional counter to measure the neutron energy spectrum between 50 keV and 5 MeV and a tissue equivalent proportional counter (TEPC) to measure absorbed neutron dose

  13. Monte Carlo method for critical systems in infinite volume: The planar Ising model.

    Science.gov (United States)

    Herdeiro, Victor; Doyon, Benjamin

    2016-10-01

    In this paper we propose a Monte Carlo method for generating finite-domain marginals of critical distributions of statistical models in infinite volume. The algorithm corrects the problem of the long-range effects of boundaries associated to generating critical distributions on finite lattices. It uses the advantage of scale invariance combined with ideas of the renormalization group in order to construct a type of "holographic" boundary condition that encodes the presence of an infinite volume beyond it. We check the quality of the distribution obtained in the case of the planar Ising model by comparing various observables with their infinite-plane prediction. We accurately reproduce planar two-, three-, and four-point of spin and energy operators. We also define a lattice stress-energy tensor, and numerically obtain the associated conformal Ward identities and the Ising central charge.

  14. Estimation of the incidence of late bladder and rectum complications after high-dose (70-78 Gy) conformal radiotherapy for prostate cancer, using dose-volume histograms

    International Nuclear Information System (INIS)

    Boersma, Liesbeth J.; Brink, Mandy van den; Bruce, Allison M.; Shouman, Tarek; Gras, Luuk; Velde, Annet te; Lebesque, Joos V.

    1998-01-01

    Purpose: To investigate whether Dose-Volume Histogram (DVH) parameters can be used to identify risk groups for developing late gastrointestinal (GI) and genitourinary (GU) complications after conformal radiotherapy for prostate cancer. Methods and Materials: DVH parameters were analyzed for 130 patients with localized prostate cancer, treated with conformal radiotherapy in a dose-escalating protocol (70-78 Gy, 2 Gy per fraction). The incidence of late (>6 months) GI and GU complications was classified using the RTOG/EORTC and the SOMA/LENT scoring system. In addition, GI complications were divided in nonsevere and severe (requiring one or more laser treatments or blood transfusions) rectal bleeding. The median follow-up time was 24 months. We investigated whether rectal and bladder wall volumes, irradiated to various dose levels, correlated with the observed actuarial incidences of GI and GU complications, using volume as a continuous variable. Subsequently, for each dose level in the DVH, the rectal wall volumes were dichotomized using different volumes as cutoff levels. The impact of the total radiation dose, and the maximum radiation dose in the rectal and bladder wall was analyzed as well. Results: The actuarial incidence at 2 years for GI complications ≥Grade II was 14% (RTOG/EORTC) or 20% (SOMA/LENT); for GU complications ≥Grade III 8% (RTOG/EORTC) or 21% (SOMA/LENT). Neither for GI complications ≥Grade II (RTOG/EORTC or SOMA/LENT), nor for GU complications ≥Grade III (RTOG/EORTC or SOMA/LENT), was a significant correlation found between any of the DVH parameters and the actuarial incidence of complications. For severe rectal bleeding (actuarial incidence at 2 years 3%), four consecutive volume cutoff levels were found, which significantly discriminated between high and low risk. A trend was observed that a total radiation dose ≥ 74 Gy (or a maximum radiation dose in the rectal wall >75 Gy) resulted in a higher incidence of severe rectal bleeding (p

  15. SU-E-T-525: Dose Volume Histograms (DVH) Analysis and Comparison with ICRU Point Doses in MRI Guided HDR Brachytherapy for Cervical Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Badkul, R; McClinton, C; Kumar, P; Mitchell, M [University of Kansas Medical Center, Kansas City, KS (United States)

    2014-06-01

    Purpose: Brachytherapy plays a crucial role in management of cervix cancer. MRI compatible applicators have made it possible to accurately delineate gross-target-volume(GTV) and organs-at-risk(OAR) volumes, as well as directly plan, optimize and adapt dose-distribution for each insertion. We sought to compare DVH of tumor-coverage and OARs to traditional Point-A, ICRU-38 bladder and rectum point-doses for four different planning-techniques. Methods: MRI based 3D-planning was performed on Nucletron-Oncentra-TPS for 3 selected patients with varying tumor-sizes and anatomy. GTV,high-risk-clinical-target-volume(HR-CTV), intermediate-risk-clinical-target-volume(IR-CTV) and OARs: rectum, bladder, sigmoid-colon, vaginal-mucosa were delineated. Three conventionally used techniques: mg-Radium-equivalent(RaEq),equal-dwell-weights(EDW), Medical-College-of-Wisconsin proposed points-optimization (MCWO) and a manual-graphical-optimization(MGO) volume-coverage based technique were applied for each patient. Prescription was 6Gy delivered to point-A in Conventional techniques (RaEq, EDW, MCWO). For MGO, goal was to achieve 90%-coverage (D90) to HR-CTV with prescription-dose. ICRU point doses for rectum and bladder, point-A doses, DVH-doses for HR-CTV-D90,0.1cc-volume(D0.1),1ccvolume( D1),2cc-volume(D2) were collected for all plans and analyzed . Results: Mean D90 for HR-CTV normalized to MGO were 0.89,0.84,0.9,1.0 for EDW, RaEq, MCWO, MGO respectively. Mean point-A doses were 21.7% higher for MGO. Conventional techniques with Point-A prescriptions under covered HR-CTV-D90 by average of 12% as compared to MGO. Rectum, bladder and sigmoid doses were highest in MGO-plans for ICRU points as well as D0.1,D1 and D2 doses. Among conventional-techniques, rectum and bladder ICRU and DVH doses(0.1,1,2cc) were not significantly different (within 7%).Rectum D0.1 provided good estimation of ICRU-rectum-point doses (within 3.9%),rectum D0.1 were higher from 0.8 to 3.9% while bladder D0

  16. Shielding for Critical Organs and Radiation Exposure Dose Distribution in Patients with High Energy Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Sung Sil; Suh, Chang Ok; Kim, Gwi Eon [Yonsei Univ., Seoul (Korea, Republic of)

    2002-03-15

    transected into transverse 36 slices of 2.5cm thickness. Photon dose was measured using a Capintec PR-06C ionization chamber with Capintec 192 electrometer (Capintec Inc., Ramsey, NJ), TLD(VICTOREEN 5000. LiF) and film dosimetry V-Omat, Kodak). In case of fetus, the dosimeter was placed at a depth of 10cm in this phantom at 100cm source to axis distance and located centrally 15cm from the inferior edge of the 30cm x 30cm{sup 2} x-ray beam irradiating the Rando phantom chest wall. A acryl bridge of size 40 cm x 40 cm{sup 2} and a clear space of about 20 cm was fabricated and placed on top of the rectangular polystyrene phantom representing the abdomen of the patient. The lead pot for testicle shielding was made as various shape, sizes, thickness and supporting stand. The scattered photon with and without shielding were measured at the representative position of the fetus and testicle. Measurement of radiation scattered dose outside fields and critical organs, like fetus position and testicle region, from chest or pelvic irradiation by large field of high energy radiation beam was performed using an ionization chamber and film dosimetry. The scattered doses outside field were measured 5 - 10% of maximum doses in fields and exponentially decrease from field margins. The scattered photon dose received the fetus and testicle from thorax field irradiation was measured about 1 mGy/Gy of photon treatment dose. Shielding construction to reduce this scattered dose was investigated using lead sheet and blocks. Lead pot shield for testicle reduced the scatter dose under 10 mGy when photon beam of 60 Gy was irradiated in abdomen region. The scattered photon dose is reduced when the lead shield was used while the no significant reduction of scattered photon dose was observed and 2-3 mm lead sheets reduced the skin dose under 80% and almost electron contamination. The results indicate that it was possible to improve shielding to reduce scattered photon for fetus and testicle when a young

  17. Single induction dose of etomidate versus other induction agents for endotracheal intubation in critically ill patients.

    Science.gov (United States)

    Bruder, Eric A; Ball, Ian M; Ridi, Stacy; Pickett, William; Hohl, Corinne

    2015-01-08

    The use of etomidate for emergency airway interventions in critically ill patients is very common. In one large registry trial, etomidate was the most commonly used agent for this indication. Etomidate is known to suppress adrenal gland function, but it remains unclear whether or not this adrenal gland dysfunction affects mortality. The primary objective was to assess, in populations of critically ill patients, whether a single induction dose of etomidate for emergency airway intervention affects mortality.The secondary objectives were to address, in populations of critically ill patients, whether a single induction dose of etomidate for emergency airway intervention affects adrenal gland function, organ dysfunction, or health services utilization (as measured by intensive care unit (ICU) length of stay (LOS), duration of mechanical ventilation, or vasopressor requirements).We repeated analyses within subgroups defined by the aetiologies of critical illness, timing of adrenal gland function measurement, and the type of comparator drug used. We searched the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; CINAHL; EMBASE; LILACS; International Pharmaceutical Abstracts; Web of Science; the Database of Abstracts of Reviews of Effects (DARE); and ISI BIOSIS Citation index(SM) on 8 February 2013. We reran the searches in August 2014. We will deal with any studies of interest when we update the review.We also searched the Scopus database of dissertations and conference proceedings and the US Food and Drug Administration Database. We handsearched major emergency medicine, critical care, and anaesthesiology journals.We handsearched the conference proceedings of major emergency medicine, anaesthesia, and critical care conferences from 1990 to current, and performed a grey literature search of the following: Current Controlled Trials; National Health Service - The National Research Register; ClinicalTrials.gov; NEAR website. We included randomized controlled

  18. Evaluation of dose-volume metrics for microbeam radiation therapy dose distributions in head phantoms of various sizes using Monte Carlo simulations

    Science.gov (United States)

    Anderson, Danielle; Siegbahn, E. Albert; Fallone, B. Gino; Serduc, Raphael; Warkentin, Brad

    2012-05-01

    This work evaluates four dose-volume metrics applied to microbeam radiation therapy (MRT) using simulated dosimetric data as input. We seek to improve upon the most frequently used MRT metric, the peak-to-valley dose ratio (PVDR), by analyzing MRT dose distributions from a more volumetric perspective. Monte Carlo simulations were used to calculate dose distributions in three cubic head phantoms: a 2 cm mouse head, an 8 cm cat head and a 16 cm dog head. The dose distribution was calculated for a 4 × 4 mm2 microbeam array in each phantom, as well as a 16 × 16 mm2 array in the 8 cm cat head, and a 32 × 32 mm2 array in the 16 cm dog head. Microbeam widths of 25, 50 and 75 µm and center-to-center spacings of 100, 200 and 400 µm were considered. The metrics calculated for each simulation were the conventional PVDR, the peak-to-mean valley dose ratio (PMVDR), the mean dose and the percentage volume below a threshold dose. The PVDR ranged between 3 and 230 for the 2 cm mouse phantom, and between 2 and 186 for the 16 cm dog phantom depending on geometry. The corresponding ranges for the PMVDR were much smaller, being 2-49 (mouse) and 2-46 (dog), and showed a slightly weaker dependence on phantom size and array size. The ratio of the PMVDR to the PVDR varied from 0.21 to 0.79 for the different collimation configurations, indicating a difference between the geometric dependence on outcome that would be predicted by these two metrics. For unidirectional irradiation, the mean lesion dose was 102%, 79% and 42% of the mean skin dose for the 2 cm mouse, 8 cm cat and 16 cm dog head phantoms, respectively. However, the mean lesion dose recovered to 83% of the mean skin dose in the 16 cm dog phantom in intersecting cross-firing regions. The percentage volume below a 10% dose threshold was highly dependent on geometry, with ranges for the different collimation configurations of 2-87% and 33-96% for the 2 cm mouse and 16 cm dog heads, respectively. The results of this study

  19. Evaluation of dose-volume metrics for microbeam radiation therapy dose distributions in head phantoms of various sizes using Monte Carlo simulations

    International Nuclear Information System (INIS)

    Anderson, Danielle; Fallone, B Gino; Warkentin, Brad; Siegbahn, E Albert; Serduc, Raphael

    2012-01-01

    This work evaluates four dose-volume metrics applied to microbeam radiation therapy (MRT) using simulated dosimetric data as input. We seek to improve upon the most frequently used MRT metric, the peak-to-valley dose ratio (PVDR), by analyzing MRT dose distributions from a more volumetric perspective. Monte Carlo simulations were used to calculate dose distributions in three cubic head phantoms: a 2 cm mouse head, an 8 cm cat head and a 16 cm dog head. The dose distribution was calculated for a 4 × 4 mm 2 microbeam array in each phantom, as well as a 16 × 16 mm 2 array in the 8 cm cat head, and a 32 × 32 mm 2 array in the 16 cm dog head. Microbeam widths of 25, 50 and 75 µm and center-to-center spacings of 100, 200 and 400 µm were considered. The metrics calculated for each simulation were the conventional PVDR, the peak-to-mean valley dose ratio (PMVDR), the mean dose and the percentage volume below a threshold dose. The PVDR ranged between 3 and 230 for the 2 cm mouse phantom, and between 2 and 186 for the 16 cm dog phantom depending on geometry. The corresponding ranges for the PMVDR were much smaller, being 2–49 (mouse) and 2–46 (dog), and showed a slightly weaker dependence on phantom size and array size. The ratio of the PMVDR to the PVDR varied from 0.21 to 0.79 for the different collimation configurations, indicating a difference between the geometric dependence on outcome that would be predicted by these two metrics. For unidirectional irradiation, the mean lesion dose was 102%, 79% and 42% of the mean skin dose for the 2 cm mouse, 8 cm cat and 16 cm dog head phantoms, respectively. However, the mean lesion dose recovered to 83% of the mean skin dose in the 16 cm dog phantom in intersecting cross-firing regions. The percentage volume below a 10% dose threshold was highly dependent on geometry, with ranges for the different collimation configurations of 2–87% and 33–96% for the 2 cm mouse and 16 cm dog heads, respectively. The results of this

  20. Critical dose and toxicity index of organs at risk in radiotherapy: Analyzing the calculated effects of modified dose fractionation in non–small cell lung cancer

    International Nuclear Information System (INIS)

    Pedicini, Piernicola; Strigari, Lidia; Benassi, Marcello; Caivano, Rocchina; Fiorentino, Alba; Nappi, Antonio; Salvatore, Marco; Storto, Giovanni

    2014-01-01

    To increase the efficacy of radiotherapy for non–small cell lung cancer (NSCLC), many schemes of dose fractionation were assessed by a new “toxicity index” (I), which allows one to choose the fractionation schedules that produce less toxic treatments. Thirty-two patients affected by non resectable NSCLC were treated by standard 3-dimensional conformal radiotherapy (3DCRT) with a strategy of limited treated volume. Computed tomography datasets were employed to re plan by simultaneous integrated boost intensity-modulated radiotherapy (IMRT). The dose distributions from plans were used to test various schemes of dose fractionation, in 3DCRT as well as in IMRT, by transforming the dose-volume histogram (DVH) into a biological equivalent DVH (BDVH) and by varying the overall treatment time. The BDVHs were obtained through the toxicity index, which was defined for each of the organs at risk (OAR) by a linear quadratic model keeping an equivalent radiobiological effect on the target volume. The less toxic fractionation consisted in a severe/moderate hyper fractionation for the volume including the primary tumor and lymph nodes, followed by a hypofractionation for the reduced volume of the primary tumor. The 3DCRT and IMRT resulted, respectively, in 4.7% and 4.3% of dose sparing for the spinal cord, without significant changes for the combined-lungs toxicity (p 20 in the combined lungs (5.5% in IMRT), and also significant dose sparing for all the other OARs (p < 0.001). The toxicity index allows to choose fractionation schedules with reduced toxicity for all the OARs and equivalent radiobiological effect for the tumor in 3DCRT, as well as in IMRT, treatments of NSCLC

  1. Dose volume histogram analysis of normal structures associated with accelerated partial breast irradiation delivered by high dose rate brachytherapy and comparison with whole breast external beam radiotherapy fields

    Directory of Open Access Journals (Sweden)

    Mutyala Subhakar

    2008-11-01

    Full Text Available Abstract Purpose To assess the radiation dose delivered to the heart and ipsilateral lung during accelerated partial breast brachytherapy using a MammoSite™ applicator and compare to those produced by whole breast external beam radiotherapy (WBRT. Materials and methods Dosimetric analysis was conducted on patients receiving MammoSite breast brachytherapy following conservative surgery for invasive ductal carcinoma. Cardiac dose was evaluated for patients with left breast tumors with a CT scan encompassing the entire heart. Lung dose was evaluated for patients in whom the entire lung was scanned. The prescription dose of 3400 cGy was 1 cm from the balloon surface. MammoSite dosimetry was compared to simulated WBRT fields with and without radiobiological correction for the effects of dose and fractionation. Dose parameters such as the volume of the structure receiving 10 Gy or more (V10 and the dose received by 20 cc of the structure (D20, were calculated as well as the maximum and mean doses received. Results Fifteen patients were studied, five had complete lung data and six had left-sided tumors with complete cardiac data. Ipsilateral lung volumes ranged from 925–1380 cc. Cardiac volumes ranged from 337–551 cc. MammoSite resulted in a significantly lower percentage lung V30 and lung and cardiac V20 than the WBRT fields, with and without radiobiological correction. Conclusion This study gives low values for incidental radiation received by the heart and ipsilateral lung using the MammoSite applicator. The volume of heart and lung irradiated to clinically significant levels was significantly lower with the MammoSite applicator than using simulated WBRT fields of the same CT data sets. Trial registration Dana Farber Trial Registry number 03-179

  2. Brachytherapy dose-volume histogram computations using optimized stratified sampling methods

    International Nuclear Information System (INIS)

    Karouzakis, K.; Lahanas, M.; Milickovic, N.; Giannouli, S.; Baltas, D.; Zamboglou, N.

    2002-01-01

    A stratified sampling method for the efficient repeated computation of dose-volume histograms (DVHs) in brachytherapy is presented as used for anatomy based brachytherapy optimization methods. The aim of the method is to reduce the number of sampling points required for the calculation of DVHs for the body and the PTV. From the DVHs are derived the quantities such as Conformity Index COIN and COIN integrals. This is achieved by using partial uniform distributed sampling points with a density in each region obtained from a survey of the gradients or the variance of the dose distribution in these regions. The shape of the sampling regions is adapted to the patient anatomy and the shape and size of the implant. For the application of this method a single preprocessing step is necessary which requires only a few seconds. Ten clinical implants were used to study the appropriate number of sampling points, given a required accuracy for quantities such as cumulative DVHs, COIN indices and COIN integrals. We found that DVHs of very large tissue volumes surrounding the PTV, and also COIN distributions, can be obtained using a factor of 5-10 times smaller the number of sampling points in comparison with uniform distributed points

  3. Link 'soil-plant' as critical in formation committed doses from uptake of long-lived radionuclides

    International Nuclear Information System (INIS)

    Kravetz, A. P.; Pavlenko, Y. A.; Grodzinsky, D. M.

    1994-01-01

    General algorithm of calculation dose from intake 137 Cs and 90 Sr depending upon level of pollution and agrochemical type of soil where trophycal chains to begin with, have been proposed. This methods consider link 'soil → plant' as critical in formation of doses from the intake long-lived radionuclides. Calculation of committed dose as function of type of soil and level of radionuclide pollution have been realized for seven main soil types of the White Russian and Ukrainian Wooded district. (author)

  4. Gastric residual volume in critically ill patients: a dead marker or still alive?

    Science.gov (United States)

    Elke, Gunnar; Felbinger, Thomas W; Heyland, Daren K

    2015-02-01

    Early enteral nutrition (EN) is consistently recommended as first-line nutrition therapy in critically ill patients since it favorably alters outcome, providing both nutrition and nonnutrition benefits. However, critically ill patients receiving mechanical ventilation are at risk for regurgitation, pulmonary aspiration, and eventually ventilator-associated pneumonia (VAP). EN may increase these risks when gastrointestinal (GI) dysfunction is present. Gastric residual volume (GRV) is considered a surrogate parameter of GI dysfunction during the progression of enteral feeding in the early phase of critical illness and beyond. By monitoring GRV, clinicians may detect patients with delayed gastric emptying earlier and intervene with strategies that minimize or prevent VAP as one of the major risks of EN. The value of periodic GRV measurements with regard to risk reduction of VAP incidence has frequently been questioned in the past years. Increasing the GRV threshold before interrupting gastric feeding results in marginal increases in EN delivery. More recently, a large randomized clinical trial revealed that abandoning GRV monitoring did not negatively affect clinical outcomes (including VAP) in mechanically ventilated patients. The results have revived the discussion on the role of GRV monitoring in critically ill, mechanically ventilated patients receiving early EN. This review summarizes the most recent clinical evidence on the use of GRV monitoring in critically ill patients. Based on the clinical evidence, it discusses the pros and cons and further addresses whether GRV is a dead marker or still alive for the nutrition management of critically ill patients. © 2014 American Society for Parenteral and Enteral Nutrition.

  5. Analysis of dose volume histogram parameters to estimate late bladder and rectum complications after high-dose (70-78 Gy) conformal radiotherapy for prostate cancer

    International Nuclear Information System (INIS)

    Boersma, L.J.; Brink, M. van den; Bruce, A.; Gras, L.; Velde, A. te; Lebesque, J.V.

    1997-01-01

    Purpose: To investigate whether Dose Volume Histogram (DVH) parameters can be used to identify risk groups for developing late gastrointestinal (GI) and genitourinary (GU) complications after conformal radiotherapy for prostate cancer, and to examine the effect of using different morbidity scoring systems on the results of these analyses. Materials and Methods: DVH parameters were analyzed for 130 patients with localized prostate cancer, treated with conformal radiotherapy in a dose-escalating protocol (70-78 Gy, 2 Gy per fraction). The incidence of late (> 6 months) GI and GU complications was scored based on questionnaires and classified using the RTOG/EORTC and the SOMA/LENT scoring system. Moreover, patients were classified as being a rectal bleeder or no rectal bleeder and a distinction was made between non-severe and severe (requiring one or more laser treatments) rectal bleeding. The median follow-up time was 22 months. It was investigated whether the relative and absolute rectal wall volumes, irradiated to various dose levels (≥ 60 Gy, ≥ 65 Gy, ≥ 70 Gy and ≥ 75 Gy) were correlated with the observed actuarial incidences of GI complications. First, the analysis was performed using volume as a continuous variable. Subsequently, for each dose level in the DVH the rectal wall volumes were dichotomized using different volumes as cut-off levels. Twenty cut-off levels were tested on their ability to discriminate between high and low risk for developing GI complications (Fig.). The relationship between bladder wall volumes irradiated to various dose levels and observed actuarial GU complications was investigated using the absolute bladder wall volumes, measured as a continuous variable. For both GI and GU complications, the role of the prescribed radiation dose and the maximum radiation dose in the rectal and bladder wall was analyzed as well. Results: None of the DVH parameters of the rectal wall was significantly correlated with the actuarial incidences of

  6. Data base on dose reduction research projects for nuclear power plants. Volume 5

    Energy Technology Data Exchange (ETDEWEB)

    Khan, T.A.; Yu, C.K.; Roecklein, A.K. [Brookhaven National Lab., Upton, NY (United States)

    1994-05-01

    This is the fifth volume in a series of reports that provide information on dose reduction research and health physics technology or nuclear power plants. The information is taken from two of several databases maintained by Brookhaven National Laboratory`s ALARA Center for the Nuclear Regulatory Commission. The research section of the report covers dose reduction projects that are in the experimental or developmental phase. It includes topics such as steam generator degradation, decontamination, robotics, improvements in reactor materials, and inspection techniques. The section on health physics technology discusses dose reduction efforts that are in place or in the process of being implemented at nuclear power plants. A total of 105 new or updated projects are described. All project abstracts from this report are available to nuclear industry professionals with access to a fax machine through the ACEFAX system or a computer with a modem and the proper communications software through the ACE system. Detailed descriptions of how to access all the databases electronically are in the appendices of the report.

  7. A comparison of dose-volume constraints derived using peak and longitudinal definitions of late rectal toxicity

    International Nuclear Information System (INIS)

    Gulliford, Sarah L.; Partridge, Mike; Sydes, Matthew R.; Andreyev, Jervoise; Dearnaley, David P.

    2010-01-01

    Background and purpose: Accurate reporting of complications following radiotherapy is an important part of the feedback loop to improve radiotherapy techniques. The definition of toxicity is normally regarded as the maximum or peak (P) grade of toxicity reported over the follow-up period. An alternative definition (integrated longitudinal toxicity (ILT)) is proposed which takes into account both the severity and the duration of the complication. Methods and materials: In this work, both definitions of toxicity were used to derive dose-volume constraints for six specific endpoints of late rectal toxicity from a cohort of patients who received prostate radiotherapy in the MRC RT01 trial. The dose-volume constraints were derived using ROC analysis for 30, 40, 50, 60, 65 and 70 Gy. Results: Statistically significant dose-volume constraints were not derived for all dose levels tested for each endpoint and toxicity definition. However, where both definitions produced constraints, there was generally good agreement. Variation in the derived dose-volume constraints was observed to be larger between endpoints than between the two definitions of toxicity. For one endpoint (stool frequency (LENT/SOM)) statistically significant dose-volume constraints were only derived using ILT. Conclusions: The longitudinal definition of toxicity (ILT) produced results consistent with those derived using peak toxicity and in some cases provided additional information which was not seen by analysing peak toxicity alone.

  8. Critical Propulsion Components. Volume 1; Summary, Introduction, and Propulsion Systems Studies

    Science.gov (United States)

    2005-01-01

    Several studies have concluded that a supersonic aircraft, if environmentally acceptable and economically viable, could successfully compete in the 21st century marketplace. However, before industry can commit to what is estimated as a 15 to 20 billion dollar investment, several barrier issues must be resolved. In an effort to address these barrier issues, NASA and Industry teamed to form the High-Speed Research (HSR) program. As part of this program, the Critical Propulsion Components (CPC) element was created and assigned the task of developing those propulsion component technologies necessary to: (1) reduce cruise emissions by a factor of 10 and (2) meet the ever-increasing airport noise restrictions with an economically viable propulsion system. The CPC-identified critical components were ultra-low emission combustors, low-noise/high-performance exhaust nozzles, low-noise fans, and stable/high-performance inlets. Propulsion cycle studies (coordinated with NASA Langley Research Center sponsored airplane studies) were conducted throughout this CPC program to help evaluate candidate components and select the best concepts for the more complex and larger scale research efforts. The propulsion cycle and components ultimately selected were a mixed-flow turbofan (MFTF) engine employing a lean, premixed, prevaporized (LPP) combustor coupled to a two-dimensional mixed compression inlet and a two-dimensional mixer/ejector nozzle. Due to the large amount of material presented in this report, it was prepared in four volumes; Volume 1: Summary, Introduction, and Propulsion System Studies, Volume 2: Combustor, Volume 3: Exhaust Nozzle, and Volume 4: Inlet and Fan/ Inlet Acoustic Team.

  9. Associations between volume changes and spatial dose metrics for the urinary bladder during local versus pelvic irradiation for prostate cancer.

    Science.gov (United States)

    Casares-Magaz, Oscar; Moiseenko, Vitali; Hopper, Austin; Pettersson, Niclas Johan; Thor, Maria; Knopp, Rick; Deasy, Joseph O; Muren, Ludvig Paul; Einck, John

    2017-06-01

    Inter-fractional variation in urinary bladder volumes during the course of radiotherapy (RT) for prostate cancer causes deviations between planned and delivered doses. This study compared planned versus daily cone-beam CT (CBCT)-based spatial bladder dose distributions, for prostate cancer patients receiving local prostate treatment (local treatment) versus prostate including pelvic lymph node irradiation (pelvic treatment). Twenty-seven patients (N = 15 local treatment; N = 12 pelvic treatment) were treated using daily image-guided RT (1.8 Gy@43-45 fx), adhering to a full bladder/empty rectum protocol. For each patient, 9-10 CBCTs were registered to the planning CT, using the clinically applied translations. The urinary bladder was manually segmented on each CBCT, 3 mm inner shells were generated, and semi and quadrant sectors were created using axial/coronal cuts. Planned and delivered DVH metrics were compared across patients and between the two groups of treatment (t-test, p bladder volume variations and the dose-volume histograms (DVH) of the bladder and its sectors were evaluated (Spearman's rank correlation coefficient, r s ). Bladder volumes varied considerably during RT (coefficient of variation: 16-58%). The population-averaged planned and delivered DVH metrics were not significantly different at any dose level. Larger treatment bladder volumes resulted in increased absolute volume of the posterior/inferior bladder sector receiving intermediate-high doses, in both groups. The superior bladder sector received less dose with larger bladder volumes for local treatments (r s  ± SD: -0.47 ± 0.32), but larger doses for pelvic treatments (r s  ± SD: 0.74 ± 0.24). Substantial bladder volume changes during the treatment course occurred even though patients were treated under a full bladder/daily image-guided protocol. Larger bladder volumes resulted in less bladder wall spared at the posterior-inferior sector, regardless the

  10. Dose-volume analysis of lung complications in the radiation treatment of malignant thymoma: a retrospective review

    International Nuclear Information System (INIS)

    Moiseenko, Vitali; Craig, Tim; Bezjak, Andrea; Dyk, Jake van

    2003-01-01

    Background and purpose: Radiation pneumonitis and fibrosis are limiting factors in radiation treatment (RT) of thoracic tumors. The objectives of this study were to quantify the influence of irradiated lung volume and dose on lung response, and to evaluate the influence of other prognostic factors. Material and methods: Treatment histories of 55 thymoma patients were evaluated retrospectively for radiation pneumonitis and fibrosis. Complications were scored as pneumonitis if observed within 6 months of completion of RT, and as fibrosis if observed after 6 months. Complications were classified as 'all pneumonitis' and 'all fibrosis' if a patient either showed symptoms (such as chronic cough and dyspnea) or radiographic changes in lung. The second group scored as 'symptomatic pneumonitis' and 'symptomatic fibrosis' consisted of patients that exhibited clinical symptoms. Dose-volume data were estimated using representative anatomies combined with available individual dose data. The Lyman NTCP model was used to assess the dependence of lung complication incidence on dose and volume. Results: The derived values of the parameters governing dose-volume dependence for symptomatic complications agreed with currently accepted and recently published values within the margins of error. Dose-response curves for complications that included radiographic changes were less steep than for symptomatic complications. The volume dependence for symptomatic fibrosis was more pronounced compared to all fibrosis. A strong correlation was observed between developing pneumonitis and developing fibrosis. Conclusions: The long survival allowed the assessment of lung complication data in thymoma patients for both acute and late response. Mean dose in lung strongly correlated with lung complications that manifest clinically. The determination of the dose-volume dependence is affected by the choice of endpoints (i.e. whether complications are scored based on clinical symptoms or radiographic

  11. Gastrointestinal toxicity of vorinostat: reanalysis of phase 1 study results with emphasis on dose-volume effects of pelvic radiotherapy

    LENUS (Irish Health Repository)

    Bratland, Ase

    2011-04-08

    Abstract Background In early-phase studies with targeted therapeutics and radiotherapy, it may be difficult to decide whether an adverse event should be considered a dose-limiting toxicity (DLT) of the investigational systemic agent, as acute normal tissue toxicity is frequently encountered with radiation alone. We have reanalyzed the toxicity data from a recently conducted phase 1 study on vorinostat, a histone deacetylase inhibitor, in combination with pelvic palliative radiotherapy, with emphasis on the dose distribution within the irradiated bowel volume to the development of DLT. Findings Of 14 eligible patients, three individuals experienced Common Terminology Criteria of Adverse Events grade 3 gastrointestinal and related toxicities, representing a toxicity profile vorinostat has in common with radiotherapy to pelvic target volumes. For each study patient, the relative volumes of small bowel receiving radiation doses between 6 Gy and 30 Gy at 6-Gy intervals (V6-V30) were determined from the treatment-planning computed tomography scans. The single patient that experienced a DLT at the second highest dose level of vorinostat, which was determined as the maximum-tolerated dose, had V6-V30 dose-volume estimates that were considerably higher than any other study patient. This patient may have experienced an adverse radiation dose-volume effect rather than a toxic effect of the investigational drug. Conclusions When reporting early-phase trial results on the tolerability of a systemic targeted therapeutic used as potential radiosensitizing agent, radiation dose-volume effects should be quantified to enable full interpretation of the study toxicity profile. Trial registration ClinicalTrials.gov: NCT00455351

  12. Antimicrobial dosing strategies in critically ill patients with acute kidney injury and high-dose continuous veno-venous hemofiltration

    NARCIS (Netherlands)

    Bouman, Catherine S. C.

    2008-01-01

    Purpose of review Delivery of appropriate antimicrobial therapy is a great challenge during continuous veno-venous hemofiltration (CVVH), particularly if the recommended higher doses are applied. The present contribution discusses the principles of drug dosing during CVVH and compares the various

  13. Exercise volume and intensity: a dose-response relationship with health benefits.

    Science.gov (United States)

    Foulds, Heather J A; Bredin, Shannon S D; Charlesworth, Sarah A; Ivey, Adam C; Warburton, Darren E R

    2014-08-01

    The health benefits of exercise are well established. However, the relationship between exercise volume and intensity and health benefits remains unclear, particularly the benefits of low-volume and intensity exercise. The primary purpose of this investigation was, therefore, to examine the dose-response relationship between exercise volume and intensity with derived health benefits including volumes and intensity of activity well below international recommendations. Generally healthy, active participants (n = 72; age = 44 ± 13 years) were assigned randomly to control (n = 10) or one of five 13-week exercise programs: (1) 10-min brisk walking 1×/week (n = 10), (2) 10-min brisk walking 3×/week (n = 10), (3) 30-min brisk walking 3×/week (n = 18), (4) 60-min brisk walking 3×/week (n = 10), and (5) 30-min running 3×/week (n = 14), in addition to their regular physical activity. Health measures evaluated pre- and post-training including blood pressure, body composition, fasting lipids and glucose, and maximal aerobic power (VO2max). Health improvements were observed among programs at least 30 min in duration, including body composition and VO2max: 30-min walking 28.8-34.5 mL kg(-1) min(-1), 60-min walking 25.1-28.9 mL kg(-1) min(-1), and 30-min running 32.4-36.4 mL kg(-1) min(-1). The greater intensity running program also demonstrated improvements in triglycerides. In healthy active individuals, a physical activity program of at least 30 min in duration for three sessions/per week is associated with consistent improvements in health status.

  14. Effect of radiotherapy dose and volume on relapse in Merkel cell cancer of the skin.

    Science.gov (United States)

    Foote, Matthew; Harvey, Jennifer; Porceddu, Sandro; Dickie, Graeme; Hewitt, Susan; Colquist, Shoni; Zarate, Dannie; Poulsen, Michael

    2010-07-01

    To assess the effect of radiotherapy (RT) dose and volume on relapse patterns in patients with Stage I-III Merkel cell carcinoma (MCC). This was a retrospective analysis of 112 patients diagnosed with MCC between January 2000 and December 2005 and treated with curative-intent RT. Of the 112 evaluable patients, 88% had RT to the site of primary disease for gross (11%) or subclinical (78%) disease. Eighty-nine percent of patients had RT to the regional lymph nodes; in most cases (71%) this was for subclinical disease in the adjuvant or elective setting, whereas 21 patients (19%) were treated with RT to gross nodal disease. With a median follow-up of 3.7 years, the 2-year and 5-year overall survival rates were 72% and 53%, respectively, and the 2-year locoregional control rate was 75%. The in-field relapse rate was 3% for primary disease, and relapse was significantly lower for patients receiving >or=50 Gy (hazard ratio [HR] = 0.22; 95% confidence interval [CI], 0.06-0.86). Surgical margins did not affect the local relapse rate. The in-field relapse rate was 11% for RT to the nodes, with dose being significant for nodal gross disease (HR = 0.24; 95% CI, 0.07-0.87). Patients who did not receive elective nodal RT had a much higher rate of nodal relapse compared with those who did (HR = 6.03; 95% CI, 1.34-27.10). This study indicates a dose-response for subclinical and gross MCC. Doses of >or=50 Gy for subclinical disease and >or=55 Gy for gross disease should be considered. The draining nodal basin should be treated in all patients. (c) 2010 Elsevier Inc. All rights reserved.

  15. SU-F-T-340: Direct Editing of Dose Volume Histograms: Algorithms and a Unified Convex Formulation for Treatment Planning with Dose Constraints

    International Nuclear Information System (INIS)

    Ungun, B; Fu, A; Xing, L; Boyd, S

    2016-01-01

    Purpose: To develop a procedure for including dose constraints in convex programming-based approaches to treatment planning, and to support dynamic modification of such constraints during planning. Methods: We present a mathematical approach that allows mean dose, maximum dose, minimum dose and dose volume (i.e., percentile) constraints to be appended to any convex formulation of an inverse planning problem. The first three constraint types are convex and readily incorporated. Dose volume constraints are not convex, however, so we introduce a convex restriction that is related to CVaR-based approaches previously proposed in the literature. To compensate for the conservatism of this restriction, we propose a new two-pass algorithm that solves the restricted problem on a first pass and uses this solution to form exact constraints on a second pass. In another variant, we introduce slack variables for each dose constraint to prevent the problem from becoming infeasible when the user specifies an incompatible set of constraints. We implement the proposed methods in Python using the convex programming package cvxpy in conjunction with the open source convex solvers SCS and ECOS. Results: We show, for several cases taken from the clinic, that our proposed method meets specified constraints (often with margin) when they are feasible. Constraints are met exactly when we use the two-pass method, and infeasible constraints are replaced with the nearest feasible constraint when slacks are used. Finally, we introduce ConRad, a Python-embedded free software package for convex radiation therapy planning. ConRad implements the methods described above and offers a simple interface for specifying prescriptions and dose constraints. Conclusion: This work demonstrates the feasibility of using modifiable dose constraints in a convex formulation, making it practical to guide the treatment planning process with interactively specified dose constraints. This work was supported by the

  16. A dual resolution measurement based Monte Carlo simulation technique for detailed dose analysis of small volume organs in the skull base region

    International Nuclear Information System (INIS)

    Yeh, Chi-Yuan; Tung, Chuan-Jung; Chao, Tsi-Chain; Lin, Mu-Han; Lee, Chung-Chi

    2014-01-01

    The purpose of this study was to examine dose distribution of a skull base tumor and surrounding critical structures in response to high dose intensity-modulated radiosurgery (IMRS) with Monte Carlo (MC) simulation using a dual resolution sandwich phantom. The measurement-based Monte Carlo (MBMC) method (Lin et al., 2009) was adopted for the study. The major components of the MBMC technique involve (1) the BEAMnrc code for beam transport through the treatment head of a Varian 21EX linear accelerator, (2) the DOSXYZnrc code for patient dose simulation and (3) an EPID-measured efficiency map which describes non-uniform fluence distribution of the IMRS treatment beam. For the simulated case, five isocentric 6 MV photon beams were designed to deliver a total dose of 1200 cGy in two fractions to the skull base tumor. A sandwich phantom for the MBMC simulation was created based on the patient's CT scan of a skull base tumor [gross tumor volume (GTV)=8.4 cm 3 ] near the right 8th cranial nerve. The phantom, consisted of a 1.2-cm thick skull base region, had a voxel resolution of 0.05×0.05×0.1 cm 3 and was sandwiched in between 0.05×0.05×0.3 cm 3 slices of a head phantom. A coarser 0.2×0.2×0.3 cm 3 single resolution (SR) phantom was also created for comparison with the sandwich phantom. A particle history of 3×10 8 for each beam was used for simulations of both the SR and the sandwich phantoms to achieve a statistical uncertainty of <2%. Our study showed that the planning target volume (PTV) receiving at least 95% of the prescribed dose (VPTV95) was 96.9%, 96.7% and 99.9% for the TPS, SR, and sandwich phantom, respectively. The maximum and mean doses to large organs such as the PTV, brain stem, and parotid gland for the TPS, SR and sandwich MC simulations did not show any significant difference; however, significant dose differences were observed for very small structures like the right 8th cranial nerve, right cochlea, right malleus and right semicircular

  17. Normal tissue complication probabilities: dependence on choice of biological model and dose-volume histogram reduction scheme

    International Nuclear Information System (INIS)

    Moiseenko, Vitali; Battista, Jerry; Van Dyk, Jake

    2000-01-01

    Purpose: To evaluate the impact of dose-volume histogram (DVH) reduction schemes and models of normal tissue complication probability (NTCP) on ranking of radiation treatment plans. Methods and Materials: Data for liver complications in humans and for spinal cord in rats were used to derive input parameters of four different NTCP models. DVH reduction was performed using two schemes: 'effective volume' and 'preferred Lyman'. DVHs for competing treatment plans were derived from a sample DVH by varying dose uniformity in a high dose region so that the obtained cumulative DVHs intersected. Treatment plans were ranked according to the calculated NTCP values. Results: Whenever the preferred Lyman scheme was used to reduce the DVH, competing plans were indistinguishable as long as the mean dose was constant. The effective volume DVH reduction scheme did allow us to distinguish between these competing treatment plans. However, plan ranking depended on the radiobiological model used and its input parameters. Conclusions: Dose escalation will be a significant part of radiation treatment planning using new technologies, such as 3-D conformal radiotherapy and tomotherapy. Such dose escalation will depend on how the dose distributions in organs at risk are interpreted in terms of expected complication probabilities. The present study indicates considerable variability in predicted NTCP values because of the methods used for DVH reduction and radiobiological models and their input parameters. Animal studies and collection of standardized clinical data are needed to ascertain the effects of non-uniform dose distributions and to test the validity of the models currently in use

  18. Incidence of late rectal bleeding in high-dose conformal radiotherapy of prostate cancer using equivalent uniform dose-based and dose-volume-based normal tissue complication probability models

    International Nuclear Information System (INIS)

    Soehn, Matthias; Yan Di; Liang Jian; Meldolesi, Elisa; Vargas, Carlos; Alber, Markus

    2007-01-01

    Purpose: Accurate modeling of rectal complications based on dose-volume histogram (DVH) data are necessary to allow safe dose escalation in radiotherapy of prostate cancer. We applied different equivalent uniform dose (EUD)-based and dose-volume-based normal tissue complication probability (NTCP) models to rectal wall DVHs and follow-up data for 319 prostate cancer patients to identify the dosimetric factors most predictive for Grade ≥ 2 rectal bleeding. Methods and Materials: Data for 319 patients treated at the William Beaumont Hospital with three-dimensional conformal radiotherapy (3D-CRT) under an adaptive radiotherapy protocol were used for this study. The following models were considered: (1) Lyman model and (2) logit-formula with DVH reduced to generalized EUD (3) serial reconstruction unit (RU) model (4) Poisson-EUD model, and (5) mean dose- and (6) cutoff dose-logistic regression model. The parameters and their confidence intervals were determined using maximum likelihood estimation. Results: Of the patients, 51 (16.0%) showed Grade 2 or higher bleeding. As assessed qualitatively and quantitatively, the Lyman- and Logit-EUD, serial RU, and Poisson-EUD model fitted the data very well. Rectal wall mean dose did not correlate to Grade 2 or higher bleeding. For the cutoff dose model, the volume receiving > 73.7 Gy showed most significant correlation to bleeding. However, this model fitted the data more poorly than the EUD-based models. Conclusions: Our study clearly confirms a volume effect for late rectal bleeding. This can be described very well by the EUD-like models, of which the serial RU- and Poisson-EUD model can describe the data with only two parameters. Dose-volume-based cutoff-dose models performed worse

  19. Multiple local minima in IMRT optimization based on dose-volume criteria

    International Nuclear Information System (INIS)

    Wu Qiuwen; Mohan, Radhe

    2002-01-01

    Multiple local minima traps are known to exist in dose-volume and dose-response objective functions. Nevertheless, their presence and consequences are not considered impediments in finding satisfactory solutions in routine optimization of IMRT plans using gradient methods. However, there is often a concern that a significantly superior solution may exist unbeknownst to the planner and that the optimization process may not be able to reach it. We have investigated the soundness of the assumption that the presence of multiple minima traps can be ignored. To find local minima, we start the optimization process a large number of times with random initial intensities. We investigated whether the occurrence of local minima depends upon the choice of the objective function parameters and the number of variables and whether their existence is an impediment in finding a satisfactory solution. To learn about the behavior of multiple minima, we first used a symmetric cubic phantom containing a cubic target and an organ-at-risk surrounding it to optimize the beam weights of two pairs of parallel-opposed beams using a gradient technique. The phantom studies also served to test our software. Objective function parameters were chosen to ensure that multiple minima would exist. Data for 500 plans, optimized with random initial beam weights, were analyzed. The search process did succeed in finding the local minima and showed that the number of minima depends on the parameters of the objective functions. It was also found that the consequences of local minima depended on the number of beams. We further searched for the multiple minima in intensity-modulated treatment plans for a head-and-neck case and a lung case. In addition to the treatment plan scores and the dose-volume histograms, we examined the dose distributions and intensity patterns. We did not find any evidence that multiple local minima affect the outcome of optimization using gradient techniques in any clinically

  20. Quantifying the Impact of Immediate Reconstruction in Postmastectomy Radiation: A Large, Dose-Volume Histogram-Based Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ohri, Nisha [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Cordeiro, Peter G. [Department of Plastic Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Keam, Jennifer [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Ballangrud, Ase [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Shi Weiji; Zhang Zhigang [Department of Biostatistics and Epidemiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Nerbun, Claire T.; Woch, Katherine M.; Stein, Nicholas F.; Zhou Ying [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); McCormick, Beryl; Powell, Simon N. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Ho, Alice Y., E-mail: HoA1234@mskcc.org [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

    2012-10-01

    Purpose: To assess the impact of immediate breast reconstruction on postmastectomy radiation (PMRT) using dose-volume histogram (DVH) data. Methods and Materials: Two hundred forty-seven women underwent PMRT at our center, 196 with implant reconstruction and 51 without reconstruction. Patients with reconstruction were treated with tangential photons, and patients without reconstruction were treated with en-face electron fields and customized bolus. Twenty percent of patients received internal mammary node (IMN) treatment. The DVH data were compared between groups. Ipsilateral lung parameters included V20 (% volume receiving 20 Gy), V40 (% volume receiving 40 Gy), mean dose, and maximum dose. Heart parameters included V25 (% volume receiving 25 Gy), mean dose, and maximum dose. IMN coverage was assessed when applicable. Chest wall coverage was assessed in patients with reconstruction. Propensity-matched analysis adjusted for potential confounders of laterality and IMN treatment. Results: Reconstruction was associated with lower lung V20, mean dose, and maximum dose compared with no reconstruction (all P<.0001). These associations persisted on propensity-matched analysis (all P<.0001). Heart doses were similar between groups (P=NS). Ninety percent of patients with reconstruction had excellent chest wall coverage (D95 >98%). IMN coverage was superior in patients with reconstruction (D95 >92.0 vs 75.7%, P<.001). IMN treatment significantly increased lung and heart parameters in patients with reconstruction (all P<.05) but minimally affected those without reconstruction (all P>.05). Among IMN-treated patients, only lower lung V20 in those without reconstruction persisted (P=.022), and mean and maximum heart doses were higher than in patients without reconstruction (P=.006, P=.015, respectively). Conclusions: Implant reconstruction does not compromise the technical quality of PMRT when the IMNs are untreated. Treatment technique, not reconstruction, is the primary

  1. Structuring polymer blends with bicontinuous phase morphology. Part II. Tailoring blends with ultralow critical volume fraction

    DEFF Research Database (Denmark)

    Lyngaae-Jørgensen, Jørgen; Utracki, Leszek

    2003-01-01

    A hypothesis providing a guideline for the development of immiscible polymer blends with co-continuous phase structure at very low critical volume fraction of one component is. postulated and experimentally verified. Based on a number of simplifying assumptions the following relation was derived......: phi(cr) = k(lambdagamma)(1-z)/(theta(b)(*))(z) where lambdagamma is a Deborah number and theta(b)(*) is a dimensionless break-up time. The equation parameters, k and z are constant that depend on the flow field hence on the blending equipment. For the studies an internal mixer with Walzenkneter...

  2. Use of kilovoltage X-ray volume imaging in patient dose calculation for head-and-neck and partial brain radiation therapy

    International Nuclear Information System (INIS)

    Hu, Weigang; Ye, Jinsong; Wang, Jiazhou; Ma, Xuejun; Zhang, Zhen

    2010-01-01

    To evaluate the accuracy of using kilovoltage x-ray cone-beam computed tomography (kV-CBCT) imaging for in vivo dose calculations. A Region-of-Interest (ROI) CT number mapping method was developed to generate the cone-beam CT number vs. relative electron density calibration curve for 3D dose calculations. The stability of the results was validated for three consecutive months. The method was evaluated on three brain tumors and three head-and-neck tumor cases. For each patient, kV-CBCT images were acquired on the first treatment day and two-week intervals on the Elekta XVI system. The delivered dose distributions were calculated by applying the patients' treatment plans to the kV-CBCT images. The resulting dose distributions and dose volume histograms (DVHs) of the tumor and critical structures were compared to the original treatment plan. The kV-CBCT electron density calibration was stable within 1.5% over a three-month period. The DVH and dose distribution comparison based on the planning CT and the initial kV-CBCT showed good agreements for majority of cases. The doses calculated from the planning CT and kV-CBCT were compared on planes perpendicular to the beam axes and passing through the isocenter. Using γ analysis with a criterion of 2 mm/2% and a threshold of 10%, more than 99.5% of the points on the iso-planes exhibited γ <1. For one patient, kV-CBCT images detected 5.8% dose variation in the right parotid due to tumor shrinkage and patient weight loss. ROI mapping method is an effective method for the creation of kV-CBCT electron density calibration curves for head-and-neck and brain tumor patients. Dose variations as monitored using kV-CBCT imaging suggest that some patients can benefit from adaptive treatment plan re-optimization

  3. Data base on dose reduction research projects for nuclear power plants. Volume 4

    Energy Technology Data Exchange (ETDEWEB)

    Khan, T.A.; Vulin, D.S.; Liang, H.; Baum, J.W. [Brookhaven National Lab., Upton, NY (United States)

    1992-08-01

    This is the fourth volume in a series of reports that provide information on dose reduction research and health physics technology for nuclear power plants. The information is taken from a data base maintained by Brookhaven National Laboratory`s ALARA Center for the Nuclear Regulatory Commission. This report presents information on 118 new or updated projects, covering a wide range of activities. Projects including steam generator degradation, decontamination, robotics, improvement in reactor materials, and inspection techniques, among others, are described in the research section of the report. The section on health physics technology includes some simple and very cost-effective projects to reduce radiation exposures. Included in this volume is a detailed description of how to access the BNL data bases which store this information. All project abstracts from this report, as well as many other useful documents, can be accessed, with permission, through our on-line system, ACE. A computer equipped with a modem, or a fax machine is all that is required to connect to ACE. Many features of ACE, including software, hardware, and communications specifics, are explained in this report.

  4. Dose Volume Histogram analysis for rectum and urethral reaction of prostate cancer

    International Nuclear Information System (INIS)

    Yanagi, Takeshi; Tsuji, Hiroshi; Kamada, Tadashi; Tsujii, Hirohiko

    2005-01-01

    The aim of this study is to evaluate the clinically relevant parameters for rectum and urethral reaction using DVH (dose volume histogram) in carbon ion radiotherapy of prostate cancer. In this year, we studied the urinary reaction mainly. 35 patients with prostate cancer were treated with carbon ion beams between June 1995 and December 1997. The applied dose was escalated from 54.0 GyE to 72.0 GyE in fixed 20 fractions. Clinical urinary reaction and rectum reaction were reviewed using Radiation Therapy Oncology Group (RTOG) scoring system for acute reactions, RTOG/European Organization for Research and Treatment of Cancer (EORTC) scoring system for late reactions. Taking the ROI (region of interest) for DVH of urethra, we used surrogate one that was derived from the observation of MR images. 35 patients were analyzed for acute urinary reaction and 34 for late urinary reaction in the study of this year. DVH analysis suggested difference among the grades for acute and late reactions. These analysis appears to be a useful tool for predicting the urinary reactions. (author)

  5. Probabilistic accident consequence uncertainty analysis -- Uncertainty assessment for deposited material and external doses. Volume 2: Appendices

    Energy Technology Data Exchange (ETDEWEB)

    Goossens, L.H.J.; Kraan, B.C.P.; Cooke, R.M. [Delft Univ. of Technology (Netherlands); Boardman, J. [AEA Technology (United Kingdom); Jones, J.A. [National Radiological Protection Board (United Kingdom); Harper, F.T.; Young, M.L. [Sandia National Labs., Albuquerque, NM (United States); Hora, S.C. [Univ. of Hawaii, Hilo, HI (United States)

    1997-12-01

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the consequence from the accidental releases of radiological material from hypothesized accidents at nuclear installations. In 1991, the US Nuclear Regulatory Commission and the Commission of the European Communities began cosponsoring a joint uncertainty analysis of the two codes. The ultimate objective of this joint effort was to systematically develop credible and traceable uncertainty distributions for the respective code input variables. A formal expert judgment elicitation and evaluation process was identified as the best technology available for developing a library of uncertainty distributions for these consequence parameters. This report focuses on the results of the study to develop distribution for variables related to the MACCS and COSYMA deposited material and external dose models. This volume contains appendices that include (1) a summary of the MACCS and COSYMA consequence codes, (2) the elicitation questionnaires and case structures, (3) the rationales and results for the panel on deposited material and external doses, (4) short biographies of the experts, and (5) the aggregated results of their responses.

  6. Iterative reconstruction technique with reduced volume CT dose index: diagnostic accuracy in pediatric acute appendicitis

    Energy Technology Data Exchange (ETDEWEB)

    Didier, Ryne A. [Oregon Health and Science University, Department of Diagnostic Radiology, DC7R, Portland, OR (United States); Vajtai, Petra L. [Oregon Health and Science University, Department of Pediatrics, Portland, OR (United States); Oregon Health and Science University, Department of Diagnostic Radiology, DC7R, Portland, OR (United States); Hopkins, Katharine L. [Oregon Health and Science University, Department of Diagnostic Radiology, DC7R, Portland, OR (United States); Oregon Health and Science University, Department of Pediatrics, Portland, OR (United States)

    2014-07-05

    Iterative reconstruction technique has been proposed as a means of reducing patient radiation dose in pediatric CT. Yet, the effect of such reductions on diagnostic accuracy has not been thoroughly evaluated. This study compares accuracy of diagnosing pediatric acute appendicitis using contrast-enhanced abdominopelvic CT scans performed with traditional pediatric weight-based protocols and filtered back projection reconstruction vs. a filtered back projection/iterative reconstruction technique blend with reduced volume CT dose index (CTDI{sub vol}). Results of pediatric contrast-enhanced abdominopelvic CT scans done for pain and/or suspected appendicitis were reviewed in two groups: A, 192 scans performed with the hospital's established weight-based CT protocols and filtered back projection reconstruction; B, 194 scans performed with iterative reconstruction technique and reduced CTDI{sub vol}. Reduced CTDI{sub vol} was achieved primarily by reductions in effective tube current-time product (mAs{sub eff}) and tube peak kilovoltage (kVp). CT interpretation was correlated with clinical follow-up and/or surgical pathology. CTDI{sub vol}, size-specific dose estimates (SSDE) and performance characteristics of the two CT techniques were then compared. Between groups A and B, mean CTDI{sub vol} was reduced by 45%, and mean SSDE was reduced by 46%. Sensitivity, specificity and diagnostic accuracy were 96%, 97% and 96% in group A vs. 100%, 99% and 99% in group B. Accuracy in diagnosing pediatric acute appendicitis was maintained in contrast-enhanced abdominopelvic CT scans that incorporated iterative reconstruction technique, despite reductions in mean CTDI{sub vol} and SSDE by nearly half as compared to the hospital's traditional weight-based protocols. (orig.)

  7. Dose-volume histogram parameters for predicting radiation pneumonitis using receiver operating characteristic curve

    International Nuclear Information System (INIS)

    Wang Dongqing; Zhang Jian; Li Baosheng; Sun Hongfu

    2012-01-01

    Objective: To assess the accuracy (ACC), sensitivity (SEN), and specificity (SPE) of dose-volume histogram (DVH) parameters in predicting the radiation pneumonitis (RP) using receiver operating characteristic (ROC) curve. Methods: Complete clinical data of 118 non-small cell lung cancer patients treated with three-dimensional conformal and intensity-modulated radiotherapy plus chemotherapy were included. Chi-square and logistic regression were retrospectively applied to analyze the correlations between DVH parameters [relative lung volume received ≥ 5 Gy (V 5 ), 10 Gy (V 10 ), 13 Gy (V 13 ), 20 Gy (V 20 ) and 30 Gy (V 30 ) and mean lung dose (MLD)] and grade 2 (and above) RP defined by the National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0. ROC curve was adopted to investigate the predictive ACC, SEN and SPE of potential DVH parameters associated with RP. Results: Total lungs V 5 , V 10 , V 13 , V 20 and MLD were all correlated to the development of RP (χ 2 =4.786, 5.771, 6.366, 7.367 and 6.945, P<0.05) according to univariate analysis. However, total lungs V 30 , patient characteristics (age, sex, KPS, tumor location, pathology) and treatment factors (prescription dose, radiotherapy technique, chemotherapy method and timing) were not contributors to RP. Logistic regression showed that V 20 of both lungs remains tight by associated with RP (χ 2 =10.96, OR=4.16, 95% CI 1.40 ∼ 12.36, P<0.05), although significant colinearity was found between V 20 and other DVH parameters (r=0.767-0.902, P<0.05). ROC curve confirmed that V 20 of both lungs could act as a predictor for RP (Z=2.038, P<0.05). The predictive ACC, SEN, and SPE were 0.645 (95% CI 0.498-0.793), 0.650 (95% CI 0.408-0.864), and 0.674 (95% CI 0.571-0.765), respectively. However, the positive predictive value was only 28.9%. Conclusions: V 20 of both lungs was correlated to the development of RP. It could act as a predictor for RP though the predictability is limited

  8. Dose Distribution in Bladder and Surrounding Normal Tissues in Relation to Bladder Volume in Conformal Radiotherapy for Bladder Cancer

    International Nuclear Information System (INIS)

    Majewski, Wojciech; Wesolowska, Iwona; Urbanczyk, Hubert; Hawrylewicz, Leszek; Schwierczok, Barbara; Miszczyk, Leszek

    2009-01-01

    Purpose: To estimate bladder movements and changes in dose distribution in the bladder and surrounding tissues associated with changes in bladder filling and to estimate the internal treatment margins. Methods and Materials: A total of 16 patients with bladder cancer underwent planning computed tomography scans with 80- and 150-mL bladder volumes. The bladder displacements associated with the change in volume were measured. Each patient had treatment plans constructed for a 'partially empty' (80 mL) and a 'partially full' (150 mL) bladder. An additional plan was constructed for tumor irradiation alone. A subsequent 9 patients underwent sequential weekly computed tomography scanning during radiotherapy to verify the bladder movements and estimate the internal margins. Results: Bladder movements were mainly observed cranially, and the estimated internal margins were nonuniform and largest (>2 cm) anteriorly and cranially. The dose distribution in the bladder worsened if the bladder increased in volume: 70% of patients (11 of 16) would have had bladder underdosed to 70%, 80%, and 90% of the prescribed dose was 23%, 20%, and 15% for the rectum and 162, 144, 123 cm 3 for the intestines, respectively) than with a 'partially full' bladder (volume that received >70%, 80%, and 90% of the prescribed dose was 28%, 24%, and 18% for the rectum and 180, 158, 136 cm 3 for the intestines, respectively). The change in bladder filling during RT was significant for the dose distribution in the intestines. Tumor irradiation alone was significantly better than whole bladder irradiation in terms of organ sparing. Conclusion: The displacements of the bladder due to volume changes were mainly related to the upper wall. The internal margins should be nonuniform, with the largest margins cranially and anteriorly. The changes in bladder filling during RT could influence the dose distribution in the bladder and intestines. The dose distribution in the rectum and bowel was slightly better with

  9. Comparison of the effect of a single dose of erythromycin with pantoprazole on gastric content volume and acidity in elective general surgery patients

    Directory of Open Access Journals (Sweden)

    Nidhi Bhatia

    2011-01-01

    Full Text Available Introduction: Pulmonary aspiration of gastric contents remains one of the most feared complications of anesthesia. A gastric pH of 2.5 or less and a volume of 25 ml (0.4 ml/kg body weight or more in average adult patients are considered critical factors for the development of pulmonary damage in adults. Materials and Methods: This study compared the efficacy of a single oral dose of erythromycin (a macrolide antibiotic with oral pantoprazole (a proton pump inhibitor on pre-operative gastric fluid volume and pH in a prospective, randomized, double-blind controlled fashion in 80 adult patients (of ASA physical status I and II planned for elective surgery under general anesthesia. Patients were divided into two groups of 40 patients each. The pantoprazole group (Group I received oral pantoprazole 40 mg and the erythromycin group (Group II received oral erythromycin 250 mg at least 1 h prior to the induction of anesthesia. After tracheal intubation, gastric fluid was aspirated via a Salem Sump tube and its volume and pH were measured. Results: Although both erythromycin and pantoprazole decreased the gastric fluid volume to a similar extent, the decrease in gastric fluid acidity by pantoprazole was significantly greater than that by erythromycin. The proportion of patients at risk of pulmonary aspiration according to traditional criteria, i.e. pH ≤2.5 and volume ≥25ml, was lower in the pantoprazole group. Conclusion: Administration of pantoprazole was found to be more useful than a sub-therapeutic dose of erythromycin in decreasing both volume and acidity of gastric content.

  10. Effect of perimuscular injection of Bothrops jararacussu venom on plasma creatine kinase levels in mice: influence of dose and volume

    Directory of Open Access Journals (Sweden)

    Calil-Elias S.

    2002-01-01

    Full Text Available The effect of dose and volume of a perimuscular injection of Bothrops jararacussu venom on myonecrosis of skeletal muscle was studied in mice. An increase of the venom dose (0.25 to 2.0 µg/g at a given volume (50 µl resulted in an increase in plasma creatine kinase (CK levels 2 h after injection. Plasma CK activity increased from the basal level of 129.27 ± 11.83 (N = 20 to 2392.80 ± 709.43 IU/l (N = 4 for the 1.0 µg/g dose. Histological analysis of extensor digitorum longus muscle 4 h after injection showed lesion of peripheral muscle fibers, disorganization of the bundles or the complete degeneration of muscle fibers. These lesions were more extensive when higher doses were injected. Furthermore, an increase in volume (12.5 to 100 µl by dilution of a given dose (0.5 µg/g also increased plasma CK levels from 482.31 ± 122.79 to 919.07 ± 133.33 IU/l (N = 4, respectively. These results indicate that care should be taken to standardize volumes and sites of venom injections.

  11. Technical basis for radiological release of Grand Junction Office Building 2. Volume 1, dose assessment

    International Nuclear Information System (INIS)

    Morris, R.; Warga, J.; Thorne, D.

    1997-07-01

    Building 2 on the US Department of Energy (DOE) Grand Junction Office (GJO) site is part of the GJO Remedial Action Program (GJORAP). During evaluation of Building 2 for determination of radiological release disposition, some inaccessible surface contamination measurements were detected to be greater than the generic surface contamination guidelines of DOE Order 5400.5 (which are functionally equivalent to US Nuclear Regulatory Commission [NRC] Regulatory Guide 1.86). Although the building is nominal in size, it houses the site telecommunications system, that is critical to continued GJO operations, and demolition is estimated at $1.9 million. Because unrestricted release under generic surface contamination guidelines is cost-prohibitive, supplemental standards consistent with DOE Order 5400.5 are being pursued. This report describes measurements and dose analysis modeling efforts to evaluate the radiation dose to members of the public who might occupy or demolish Building 2, a 2,480 square-foot (ft) building constructed in 1944. The north portion of the building was used as a shower facility for Manhattan Project uranium-processing mill workers and the south portion was a warehouse. Many originally exposed surfaces are no longer accessible for contamination surveys because expensive telecommunications equipment have been installed on the floors and mounted on panels covering the walls. These inaccessible surfaces are contaminated above generic contamination limits

  12. Sparsity constrained split feasibility for dose-volume constraints in inverse planning of intensity-modulated photon or proton therapy

    Science.gov (United States)

    Penfold, Scott; Zalas, Rafał; Casiraghi, Margherita; Brooke, Mark; Censor, Yair; Schulte, Reinhard

    2017-05-01

    A split feasibility formulation for the inverse problem of intensity-modulated radiation therapy treatment planning with dose-volume constraints included in the planning algorithm is presented. It involves a new type of sparsity constraint that enables the inclusion of a percentage-violation constraint in the model problem and its handling by continuous (as opposed to integer) methods. We propose an iterative algorithmic framework for solving such a problem by applying the feasibility-seeking CQ-algorithm of Byrne combined with the automatic relaxation method that uses cyclic projections. Detailed implementation instructions are furnished. Functionality of the algorithm was demonstrated through the creation of an intensity-modulated proton therapy plan for a simple 2D C-shaped geometry and also for a realistic base-of-skull chordoma treatment site. Monte Carlo simulations of proton pencil beams of varying energy were conducted to obtain dose distributions for the 2D test case. A research release of the Pinnacle 3 proton treatment planning system was used to extract pencil beam doses for a clinical base-of-skull chordoma case. In both cases the beamlet doses were calculated to satisfy dose-volume constraints according to our new algorithm. Examination of the dose-volume histograms following inverse planning with our algorithm demonstrated that it performed as intended. The application of our proposed algorithm to dose-volume constraint inverse planning was successfully demonstrated. Comparison with optimized dose distributions from the research release of the Pinnacle 3 treatment planning system showed the algorithm could achieve equivalent or superior results.

  13. Dose-Volume Parameters of the Corpora Cavernosa Do Not Correlate With Erectile Dysfunction After External Beam Radiotherapy for Prostate Cancer: Results From a Dose-Escalation Trial

    International Nuclear Information System (INIS)

    Wielen, Gerard J. van der; Hoogeman, Mischa S.; Dohle, Gert R.; Putten, Wim L.J. van; Incrocci, Luca

    2008-01-01

    Purpose: To analyze the correlation between dose-volume parameters of the corpora cavernosa and erectile dysfunction (ED) after external beam radiotherapy (EBRT) for prostate cancer. Methods and Materials: Between June 1997 and February 2003, a randomized dose-escalation trial comparing 68 Gy and 78 Gy was conducted. Patients at our institute were asked to participate in an additional part of the trial evaluating sexual function. After exclusion of patients with less than 2 years of follow-up, ED at baseline, or treatment with hormonal therapy, 96 patients were eligible. The proximal corpora cavernosa (crura), the superiormost 1-cm segment of the crura, and the penile bulb were contoured on the planning computed tomography scan and dose-volume parameters were calculated. Results: Two years after EBRT, 35 of the 96 patients had developed ED. No statistically significant correlations between ED 2 years after EBRT and dose-volume parameters of the crura, the superiormost 1-cm segment of the crura, or the penile bulb were found. The few patients using potency aids typically indicated to have ED. Conclusion: No correlation was found between ED after EBRT for prostate cancer and radiation dose to the crura or penile bulb. The present study is the largest study evaluating the correlation between ED and radiation dose to the corpora cavernosa after EBRT for prostate cancer. Until there is clear evidence that sparing the penile bulb or crura will reduce ED after EBRT, we advise to be careful in sparing these structures, especially when this involves reducing treatment margins

  14. Low-Dose Volume-Perfusion CT of the Brain: Effects of Radiation Dose Reduction on Performance of Perfusion CT Algorithms.

    Science.gov (United States)

    Othman, A E; Afat, S; Brockmann, C; Nikoubashman, O; Bier, G; Brockmann, M A; Nikolaou, K; Tai, J H; Yang, Z P; Kim, J H; Wiesmann, M

    2017-09-01

    We aimed to compare different computed tomography (CT) perfusion post-processing algorithms regarding image quality of perfusion maps from low-dose volume perfusion CT (VPCT) and their diagnostic performance regarding the detection of ischemic brain lesions. We included VPCT data of 21 patients with acute stroke (onset Perfusion maps (cerebral blood volume (CBV); cerebral blood flow (CBF) from original and low-dose datasets were generated using two different commercially available post-processing methods: deconvolution-based method (DC) and maximum slope algorithm (MS). The resulting DC and MS perfusion maps were compared regarding perfusion values, signal-to-noise ratio (SNR) as well as image quality and diagnostic accuracy as rated by two blinded neuroradiologists. Quantitative perfusion parameters highly correlated for both algorithms and both dose levels (r ≥ 0.613, p perfusion maps from simulated low-dose VPCT. However, MS produced CBF maps with significantly higher image quality and SNR than DC, indicating that MS might be more suitable for low-dose VPCT imaging.

  15. Evaluation of radiation doses on critical organs in the treatment of cancer of the cervix using HDR-brachytherapy

    International Nuclear Information System (INIS)

    Soares, Taciana; Jansem, Teresa

    2000-01-01

    High dose-rate (HDR) brachytherapy is one type of treatment of the cervix carcinoma. During the planning for this therapy, especial attention is given to proximal normal organs such as bladder and rectum. In fact, due to their radiosensibility and localization, bladder and rectum are considered as critical organs. In this work we have studied the influence of the positioning of patient legs in the dose delivered to these critical organs in the treatment of cancer of the cervix using HDR-brachytherapy. (author)

  16. Challenges and Potential Solutions – Individualised Antibiotic Dosing at the Bedside for Critically Ill Patients: a structured review

    Science.gov (United States)

    Roberts, Jason A.; Aziz, Mohd Hafiz Abdul; Lipman, Jeffrey; Mouton, Johan W.; Vinks, Alexander A.; Felton, Timothy W.; Hope, William W.; Farkas, Andras; Neely, Michael N.; Schentag, Jerome J.; Drusano, George; Frey, Otto R.; Theuretzbacher, Ursula; Kuti, Joseph L.

    2014-01-01

    Summary Infections in critically ill patients are associated with persistently poor clinical outcomes. These patients have severely altered and variable antibiotic pharmacokinetics and are infected by less susceptible pathogens. Antibiotic dosing that does not account for these features is likely to result in sub-optimal outcomes. In this paper, we review the patient- and pathogen-related challenges that contribute to inadequate antibiotic dosing and discuss how a process for individualised antibiotic therapy, that increases the accuracy of dosing, can be implemented to further optimise care for the critically ill patient. The process for optimised antibiotic dosing firstly requires determination of the physiological derangements in the patient that can alter antibiotic concentrations including altered fluid status, microvascular failure, serum albumin concentrations as well as altered renal and hepatic function. Secondly, knowledge of the susceptibility of the infecting pathogen should be determined through liaison with the microbiology laboratory. The patient and pathogen challenges can then be solved by combining susceptibility data with measured antibiotic concentration data (where possible) into a clinical dosing software. Such software uses pharmacokinetic-pharmacodynamic (PK/PD) models from critically ill patients to accurately predict the dosing requirements for the individual patient with the aim of optimising antibiotic exposure and maximising effectiveness. PMID:24768475

  17. Scale-4 analysis of pressurized water reactor critical configurations: Volume 5, North Anna Unit 1 Cycle 5

    International Nuclear Information System (INIS)

    Bowman, S.M.; Suto, T.

    1996-10-01

    ANSI/ANS 8.1 requires that calculational methods for away-from- reactor (AFR) criticality safety analyses be validated against experiment. This report summarizes part of the ongoing effort to benchmark AFR criticality analysis methods using selected critical configurations from commercial PWRs. Codes and data in the SCALE-4 code system were used. This volume documents the SCALE system analysis of one reactor critical configuration for North Anna Unit 1 Cycle 5. The KENO V.a criticality calculations for the North Anna 1 Cycle 5 beginning-of-cycle model yielded a value for k eff of 1. 0040±0.0005

  18. SU-F-I-38: Patient Organ Specific Dose Assessment in Coronary CT Angiograph Using Voxellaized Volume Dose Index in Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Fallal, Mohammadi Gh.; Riyahi, Alam N.; Graily, Gh. [Tehran University of Medical Scienced(TUMS), School of Medicine, Department of Nedical Physics and Biomedical Engineering, Tehran (Iran, Islamic Republic of); Paydar, R. [Iran University of Medical Sciences(IUMS), Allied Medicine Faculty, Department of radiation Sciences, Tehran (Iran, Islamic Republic of)

    2016-06-15

    Purpose: Clinical use of multi detector computed tomography(MDCT) in diagnosis of diseases due to high speed in data acquisition and high spatial resolution is significantly increased. Regarding to the high radiation dose in CT and necessity of patient specific radiation risk assessment, the adoption of new method in the calculation of organ dose is completely required and necessary. In this study by introducing a conversion factor, patient organ dose in thorax region based on CT image data using MC system was calculated. Methods: The geometry of x-ray tube, inherent filter, bow tie filter and collimator were designed using EGSnrc/BEAMnrc MC-system component modules according to GE-Light-speed 64-slices CT-scanner geometry. CT-scan image of patient thorax as a specific phantom was voxellised with 6.25mm3 in voxel and 64×64×20 matrix size. Dose to thorax organ include esophagus, lung, heart, breast, ribs, muscle, spine, spinal cord with imaging technical condition of prospectively-gated-coronary CT-Angiography(PGT) as a step and shoot method, were calculated. Irradiation of patient specific phantom was performed using a dedicated MC-code as DOSXYZnrc with PGT-irradiation model. The ratio of organ dose value calculated in MC-method to the volume CT dose index(CTDIvol) reported by CT-scanner machine according to PGT radiation technique has been introduced as conversion factor. Results: In PGT method, CTDIvol was 10.6mGy and Organ Dose/CTDIvol conversion factor for esophagus, lung, heart, breast, ribs, muscle, spine and spinal cord were obtained as; 0.96, 1.46, 1.2, 3.28. 6.68. 1.35, 3.41 and 0.93 respectively. Conclusion: The results showed while, underestimation of patient dose was found in dose calculation based on CTDIvol, also dose to breast is higher than the other studies. Therefore, the method in this study can be used to provide the actual patient organ dose in CT imaging based on CTDIvol in order to calculation of real effective dose(ED) based on organ dose

  19. Impact of Node Negative Target Volume Delineation on Contralateral Parotid Gland Dose Sparing Using IMRT in Head and Neck Cancer.

    Science.gov (United States)

    Magnuson, William J; Urban, Erich; Bayliss, R Adam; Harari, Paul M

    2015-06-01

    There is considerable practice variation in treatment of the node negative (N0) contralateral neck in patients with head and neck cancer. In this study, we examined the impact of N0 neck target delineation volume on radiation dose to the contralateral parotid gland. Following institutional review board approval, 12 patients with head and neck cancer were studied. All had indications for treatment of the N0 neck, such as midline base of tongue or soft palate extension or advanced ipsilateral nodal disease. The N0 neck volumes were created using the Radiation Therapy Oncology Group head and neck contouring atlas. The physician-drawn N0 neck clinical target volume (CTV) was expanded by 25% to 200% to generate volume variation, followed by a 3-mm planning target volume (PTV) expansion. Surrounding organs at risk were contoured and complete intensity-modulated radiation therapy plans were generated for each N0 volume expansion. The median N0 target volume drawn by the radiation oncologist measured 93 cm(3) (range 71-145). Volumetric expansion of the N0 CTV by 25% to 200% increased the resultant mean dose to the contralateral parotid gland by 1.4 to 8.5 Gray (Gy). For example, a 4.1-mm increase in the N0 neck CTV translated to a 2.0-Gy dose increase to the parotid, 7.4 mm to a 4.5 Gy dose increase, and 12.5 mm to an 8.5 Gy dose increase, respectively. The treatment volume designated for the N0 neck has profound impact on resultant dose to the contralateral parotid gland. Variations of up to 15 mm are routine across physicians in target contouring, reflecting individual preference and training expertise. Depending on the availability of immobilization and image guidance techniques, experts commonly recommend 3 to 10 mm margin expansions to generate the PTV. Careful attention to the original volume of the N0 neck CTV, as well as expansion margins, is important in achieving effective contralateral gland sparing to reduce the resultant xerostomia and dysguesia that may ensue

  20. Dose critical in-vivo detection of anti-cancer drug levels in blood

    Science.gov (United States)

    Miller, Holly H.; Hirschfeld, deceased, Tomas B.

    1991-01-01

    A method and apparatus are disclosed for the in vivo and in vitro detection and measurement of dose critical levels of DNA-binding anti-cancer drug levels in biological fluids. The apparatus comprises a laser based fiber optic sensor (optrode) which utilizes the secondary interactions between the drug and an intercalating fluorochrome bound to a probe DNA, which in turn is attached to the fiber tip at one end thereof. The other end of the optical fiber is attached to an illumination source, detector and recorder. The fluorescence intensity is measured as a function of the drug concentration and its binding constant to the probe DNA. Anticancer drugs which lend themselves to analysis by the use of the method and the optrode of the present invention include doxorubicin, daunorubicin, carminomycin, aclacinomycin, chlorambucil, cyclophosphamide, methotrexate, 5-uracil, arabinosyl cytosine, mitomycin, cis-platinum 11 diamine dichloride procarbazine, vinblastine vincristine and the like. The present method and device are suitable for the continuous monitoring of the levels of these and other anticancer drugs in biological fluids such as blood, serum, urine and the like. The optrode of the instant invention also enables the measurement of the levels of these drugs from a remote location and from multiple samples.

  1. Systematic review of dose-volume parameters in the prediction of esophagitis in thoracic radiotherapy

    International Nuclear Information System (INIS)

    Rose, Jim; Rodrigues, George; Yaremko, Brian; Lock, Michael; D'Souza, David

    2009-01-01

    Purpose: With dose escalation and increasing use of concurrent chemoradiotherapy, radiation esophagitis (RE) remains a common treatment-limiting acute side effect in the treatment of thoracic malignancies. The advent of 3DCT planning has enabled investigators to study esophageal dose-volume histogram (DVH) parameters as predictors of RE. The purpose of this study was to assess published dosimetric parameters and toxicity data systematically in order to define reproducible predictors of RE, both for potential clinical use, and to provide recommendations for future research in the field. Materials and methods: We performed a systematic literature review of published studies addressing RE in the treatment of lung cancer and thymoma. Our search strategy included a variety of electronic medical databases, textbooks and bibliographies. Both prospective and retrospective clinical studies were included. Information relating to the relationship among measured dosimetric parameters, patient demographics, tumor characteristics, chemotherapy and RE was extracted and analyzed. Results: Eighteen published studies were suitable for analysis. Eleven of these assessed acute RE, while the remainder assessed both acute and chronic RE together. Heterogeneity of esophageal contouring practices, individual differences in information reporting and variability of RE outcome definitions were assessed. Well-described clinical and logistic modeling directly related V 35Gy , V 60Gy and SA 55Gy to clinically significant RE. Conclusions: Several reproducible dosimetric parameters exist in the literature, and these may be potentially relevant in the prediction of RE in the radiotherapy of thoracic malignancies. Further clarification of the predictive relationship between such standardized dosimetric parameters and observed RE outcomes is essential to develop efficient radiation treatment planning in locally advanced NSCLC in the modern concurrent chemotherapy and image-guided IMRT era.

  2. Evaluation of different set-up error corrections on dose-volume metrics in prostate IMRT using CBCT images

    International Nuclear Information System (INIS)

    Hirose, Yoshinori; Tomita, Tsuneyuki; Kitsuda, Kenji; Notogawa, Takuya; Miki, Katsuhito; Nakamura, Mitsuhiro; Nakamura, Kiyonao; Ishigaki, Takashi

    2014-01-01

    We investigated the effect of different set-up error corrections on dose-volume metrics in intensity-modulated radiotherapy (IMRT) for prostate cancer under different planning target volume (PTV) margin settings using cone-beam computed tomography (CBCT) images. A total of 30 consecutive patients who underwent IMRT for prostate cancer were retrospectively analysed, and 7-14 CBCT datasets were acquired per patient. Interfractional variations in dose-volume metrics were evaluated under six different set-up error corrections, including tattoo, bony anatomy, and four different target matching groups. Set-up errors were incorporated into planning the isocenter position, and dose distributions were recalculated on CBCT images. These processes were repeated under two different PTV margin settings. In the on-line bony anatomy matching groups, systematic error (Σ) was 0.3 mm, 1.4 mm, and 0.3 mm in the left-right, anterior-posterior (AP), and superior-inferior directions, respectively. Σ in three successive off-line target matchings was finally comparable with that in the on-line bony anatomy matching in the AP direction. Although doses to the rectum and bladder wall were reduced for a small PTV margin, averaged reductions in the volume receiving 100% of the prescription dose from planning were within 2.5% under all PTV margin settings for all correction groups, with the exception of the tattoo set-up error correction only (≥ 5.0%). Analysis of variance showed no significant difference between on-line bony anatomy matching and target matching. While variations between the planned and delivered doses were smallest when target matching was applied, the use of bony anatomy matching still ensured the planned doses. (author)

  3. Dose distribution assessment (comparison) in the target volume treated with VMAT given by the planning system and evaluated by TL dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Bravim, A.; Sakuraba, R.K.; Campos, L.L., E-mail: ambravim@hotmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Gerencia de Metrologia das Radiacoes

    2015-07-01

    Volumetric-modulated arc therapy (VMAT) is a relatively new therapy technique in which treatment is delivered using a cone beam that rotates around the patient. The radiation is delivered in a continuous gantry rotation while the cone beam is modulated by the intertwining of dynamic multileaf collimators (MLCs). Studies of VMAT plans have shown reduction in the treatment delivery time and monitor units (MU) comparable to IMRT plans improving major comfort to the patient and reducing uncertainties associated with patient movement during treatment. The treatment using VMAT minimizes the biological effects of radiation to critical structures near to the target volumes and produces excellent dose distributions. The dosimetry of ionizing radiation is essential for the radiological protection programs for quality assurance and licensing of equipment. For radiation oncology a quality assurance program is essentially to maintain the quality of patient care. As the VMAT is a new technique of radiation therapy it is important to optimize quality assurance mechanisms to ensure that tests are performed in order to preserve the patient and the equipment. This paper aims to determinate the dose distribution in the target volume (tumor to be treated) and the scattered dose distribution in the risk organs for VMAT technique comparing data given by the planning system and thermoluminescent (TL) response. (author)

  4. A novel dose-volume metric for optimizing therapeutic ratio through fractionation: retrospective analysis of lung cancer treatments.

    Science.gov (United States)

    Keller, Harald; Hope, Andrew; Meier, Gabriel; Davison, Matt

    2013-08-01

    To explore the potential of a novel dose-volume based metric to assist in the selection of optimal fractionation schedules for lung cancer patients. Selecting the dose per fraction that maximizes the therapeutic ratio via a linear-quadratic effect on normal tissue complication probability and tumor cell survival is an optimization problem. The mathematical solution reveals that the optimal fractionation schedule is determined by a generalized dose ratio between the normal tissue and the tumor, here termed the bifurcation number B, that can be derived from the dose-volume histogram of the normal tissue. The bifurcation number characterizes the volume effect of a normal tissue and its dependency on the fractionation schedule. The clinical relevance of the bifurcation number was evaluated in 46 patients previously treated for nonsmall cell lung cancer (NSCLC) according to various fractionation protocols. Bifurcation numbers were computed for both lung and esophagus as the normal tissues. The value of the bifurcation number determines whether the volume effect reverses the traditional radiobiological advantage of small dose per fraction for the normal tissue. If B is smaller than the ratio of alpha/beta ratios between normal tissue and tumor, then a single fraction is optimal; otherwise the optimal treatment is an infinite number of doses (hence the name "bifurcation" number). These fractionation schedules correspond clinically to hypo- and standard/hyperfractionation, respectively. Compared with traditional dose-volume metrics, the bifurcation number is a unitless ratio and independent of dose fractionation. The B-numbers derived from the clinical treatment plans are also strongly consistent with historically prescribed clinical fractionation protocols for NSCLC treatments. The B-numbers for esophagus and lung for all patients receiving a high dose per fraction protocol (>7.5 Gy/fraction) were all smaller than the B-numbers for the patients receiving standard 2 Gy

  5. Visualization of murine intranasal dosing efficiency using luminescent Francisella tularensis: effect of instillation volume and form of anesthesia.

    Directory of Open Access Journals (Sweden)

    Mark A Miller

    Full Text Available Intranasal instillation is a widely used procedure for pneumonic delivery of drugs, vaccine candidates, or infectious agents into the respiratory tract of research mice. However, there is a paucity of published literature describing the efficiency of this delivery technique. In this report we have used the murine model of tularemia, with Francisella tularensis live vaccine strain (FTLVS infection, to evaluate the efficiency of pneumonic delivery via intranasal dosing performed either with differing instillation volumes or different types of anesthesia. FTLVS was rendered luminescent via transformation with a reporter plasmid that constitutively expressed the Photorhabdus luminescens lux operon from a Francisella promoter. We then used an IVIS Spectrum whole animal imaging system to visualize FT dissemination at various time points following intranasal instillation. We found that instillation of FT in a dose volume of 10 µl routinely resulted in infection of the upper airways but failed to initiate infection of the pulmonary compartment. Efficient delivery of FT into the lungs via intranasal instillation required a dose volume of 50 µl or more. These studies also demonstrated that intranasal instillation was significantly more efficient for pneumonic delivery of FTLVS in mice that had been anesthetized with inhaled (isoflurane vs. parenteral (ketamine/xylazine anesthesia. The collective results underscore the need for researchers to consider both the dose volume and the anesthesia type when either performing pneumonic delivery via intranasal instillation, or when comparing studies that employed this technique.

  6. Analytical evaluation of dose measurement of critical accident at SILENE (Contract research)

    CERN Document Server

    Nakamura, T; Tonoike, K

    2003-01-01

    Institute for Radioprotection and Nuclear Safety (IRSN) and the OECD Nuclear Energy Agency (NEA) jointly organized SILENE Accident Dosimetry Intercomparison Exercise to intercompare the dose measurement systems of participating countries. Each participating country carried out dose measurements in the same irradiation field, and the measurement results were mutually compared. The participated in the exercise to measure the doses of gamma rays and neutron from SILENE by using thermoluminescence dosimeters (TLD's) and an alanine dosimeter. In this examination, the derived evaluation formulae for obtaining a tissue-absorbed dose from measured value (ambient dose equivalent) of TLD for neutron. We reported the tissue-absorbed dose computed using this evaluation formula to OECD/NEA. TLD's for neutron were irradiated in the TRACY facility to verify the evaluation formulae. The results of TLD's were compared with the calculations of MCNP and measurements with alanine dose meter. We found that the ratio of the dose b...

  7. Dose-escalated radiotherapy for unresectable or locally recurrent pancreatic cancer: Dose volume analysis, toxicity and outcome of 28 consecutive patients.

    Directory of Open Access Journals (Sweden)

    Sebastian Zschaeck

    Full Text Available The role of radiotherapy for unresectable pancreatic cancer is controversial. A benefit of additional radiotherapy is supported by some observations. A dose-effect relationship was recently found by dose escalation employing image guided and intensity modulated radiotherapy.We retrospectively evaluated 28 consecutive patients, all with history of extensive prior therapies for unresectable locally advanced/ recurrent pancreatic cancer (LAPC/LRPC. Treatment was delivered by helical tomotherapy after daily position verification with computed tomography. Dose to the planned target volume (PTV was 51 Gy, while the dose to the macroscopic tumor was escalated by a simultaneous integrated boost to a median cumulative dose of 66 Gy (60-66 Gy. Concomitant chemotherapy consisted mainly of capecitabine (n = 23.10 of 28 patients presented acute toxicities > grade 2, one patient succumbed to gastrointestinal bleeding after treatment. No correlations of toxicities and dose volume histograms (DVH of retrospectively delineated small bowel loops were observed, although average small bowel volume receiving ≥ 20 Gy was 374 ml. DVH analyses revealed a correlation of splenic parameters and acute toxicity: Vomiting, anorexia, dehydration, hematologic toxicity, fatigue, combined gastro-intestinal toxicity wit R-values between 0.392 and 0.561 (all p-values > 0.05. Only one patient developed late toxicities > grade 2. With an average follow-up time in surviving patients of 14 months median overall survival time was 19 months and median time to local recurrence 13 months. In 8 patients with available imaging of local recurrence: 5 in field recurrences, 2 marginal recurrences and one lymph node recurrence outside the high dose radiation field were observed. In univariate analysis only ΔCA-19-9 during radiotherapy was associated with local control (p = 0.029 and overall survival (p = 0.049.Dose escalated normo-fractionated radiotherapy for LAPC/LRPC seems feasible and

  8. Dose-volume histogram evaluation of prone and supine patient position in external beam radiotherapy for cervical and endometrial cancer

    International Nuclear Information System (INIS)

    Pinkawa, Michael; Gagel, Bernd; Demirel, Cengiz; Schmachtenberg, Axel; Asadpour, Branka; Eble, Michael J.

    2003-01-01

    Background and purpose: To evaluate the influence of patient positioning on dose-volume histograms of organs at risk in external beam radiotherapy for cervical and endometrial cancer. Materials and methods: In 20 patients scheduled for definitive (7) or postoperative (13) external beam radiotherapy of the pelvis treatment planning CT scans were performed in supine and prone (belly board) positions. After volume definition of target and organs at risk treatment plans were calculated applying the four-field box technique. The dose-volume histograms of organs at risk were compared. Results: Radiotherapy in prone position causes a reduction of the bladder portion (mean 15%, p<0.001) and an increase of the rectum portion (mean 11%, p<0.001) within the 90% isodose. A reduction of the bowel portion could only be observed in postoperatively treated patients (mean 13%, p<0.001). In definitive radiotherapy the target volume increases in supine position (mean 7%, p=0.02) due to an anterior tumour/uterus movement, so that bowel portions within the 90% isodose are similar. The bladder filling correlates with a reduction of bladder and bowel (postoperatively treated patients) dose. Conclusions: External beam radiotherapy of the pelvis should be performed in prone position in postoperative patients because of best bowel protection. Considering the additional HDR brachytherapy rectum protection takes the highest priority in definitive treatment--the requirements are best met in supine position. An adequate bladder filling is important to reduce the irradiated bladder and bowel volumes

  9. SU-E-T-13: A Comparative Dosimetric Study On Radio-Dynamic Therapy for Pelvic Cancer Treatment: Strategies for Bone Marrow Dose and Volume Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Li, C [Fox Chase Cancer Center, Philadelphia, PA (United States); Renmin Hospital of Wuhan University, Wuhan, Hubei Province (China); Wang, B; Dong, Z; Ma, C [Fox Chase Cancer Center, Philadelphia, PA (United States); Ge, W; Xu, L [Renmin Hospital of Wuhan University, Wuhan, Hubei Province (China)

    2015-06-15

    Purpose: Radio-dynamic therapy (RDT) is a potentially effective modality for local and systemic cancer treatment. Using RDT, the administration of a radio-sensitizer enhances the biological effect of high-energy photons. Although the sensitizer uptake ratio of tumor to normal tissue is normally high, one cannot simply neglect its effect on critical structures. In this study, we aim to explore planning strategies to improve bone marrow sparing without compromising the plan quality for RDT treatment of pelvic cancers. Methods: Ten cervical and ten prostate cancer patients who previously received radiotherapy at our institution were selected for this study. For each patient, nine plans were created using the Varian Eclipse treatmentplanning-system (TPS) with 3D-CRT, IMRT, and VMAT delivery techniques containing various gantry angle combinations and optimization parameters (dose constraints to the bone marrow). To evaluate the plans for bone marrow sparing, the dose-volume parameters V5, V10, V15, V20, V30, and V40 for bone marrow were examined. Effective doseenhancement factors for the sensitizer were used to weigh the dose-volume histograms for various tissues from individual fractions. Results: The planning strategies had different impacts on bone marrow sparing for the cervical and prostate cases. For the cervical cases, provided the bone marrow constraints were properly set during optimization, the dose to bone marrow sparing was found to be comparable between different IMRT and VMAT plans regardless of the gantry angle selection. For the prostate cases, however, careful selection of gantry angles could dramatically improve the bone marrow sparing, although the dose distribution in bone marrow was clinically acceptable for all prostate plans that we created. Conclusion: For intensity-modulated RDT planning for cervical cancer, planners should set bone marrow constraints properly to avoid any adverse damage, while for prostate cancer one can carefully select gantry

  10. Digital Drug Dosing: Dosing in Drug Assays by Light-Defined Volumes of Hydrogels with Embedded Drug-Loaded Nanoparticles

    DEFF Research Database (Denmark)

    Faralli, Adele; Melander, Fredrik; Larsen, Esben Kjær Unmack

    2014-01-01

    Polyethylene glycol (PEG)-based hydrogels are widely used for biomedical applications, including matrices for controlled drug release. We present a method for defining drug dosing in screening assays by light-activated cross-linking of PEG-diacrylate hydrogels with embedded drug-loaded liposome...

  11. Tolerance and dose-volume relationship of intrathoracic stomach irradiation after esophagectomy for patients with thoracic esophageal squamous cell carcinoma.

    Science.gov (United States)

    Liu, Qi; Cai, Xu-Wei; Fu, Xiao-Long; Chen, Jun-Chao; Xiang, Jia-Qing

    2015-10-13

    To identify the tolerance of radiation with a high prescribed dose and predictors for the development of intrathoracic stomach toxicity in patients with thoracic esophageal squamous cell carcinoma (SCC) after esophagectomy followed by gastric conduit reconstruction. From 2011 to 2013, 105 patients after esophagectomy were treated with postoperative radiotherapy. The intrathoracic stomach was outlined with the calculation of a dose-volume histogram (DVH) for the initial intended treatment of 6020 cGy or 6300 cGy. The volume of the intrathoracic stomach receiving each dose was recorded at 10-Gy intervals between 10 and 40 Gy and at 5-Gy intervals between 40 and 60 Gy. The grade of toxicities was defined by the National Cancer Institute Common Toxicity Criteria version 4.0. The mean and maximum doses of the intrathoracic stomach were 2449 ± 986 cGy and 6519 ± 406 cGy, respectively. Sixteen (15.2%) and three (2.9%) experienced Common Toxicity Criteria Grade 2 and Grade 3 acute gastric toxicity. There were no Grade 4 toxicities. Fourteen patients (13.3%) exhibited late gastric complications possibly related to radiation. The volume percent of the intrathoracic stomach receiving at least 50 Gy (V50) was strongly associated with the degree of toxicity (p = 0.024, respectively). Multivariate analysis of patient and treatment-related factors revealed no other significant predictors of severe toxicities. The intrathoracic stomach is well tolerated with a high-dose irradiation for patients with esophageal SCC receiving radiotherapy after esophagectomy. A strong dose-volume relationship exists for the development of Grade 2 acute intrathoracic stomach toxicity in our study.

  12. Dose-response of critical structures in the posterior eye segment to hypofractioned stereotactic photon radiotherapy of choroidal melanoma.

    Science.gov (United States)

    Dunavoelgyi, Roman; Georg, Dietmar; Zehetmayer, Martin; Schmidt-Erfurth, Ursula; Pötter, Richard; Dörr, Wolfgang; Dieckmann, Karin

    2013-08-01

    To identify modifying factors and dose-/volume-response relationships for the retina and optic nerve related to highly conformal hypofractionated radiotherapy. Seventy-three patients undergoing hypofractionated stereotactic photon radiotherapy of choroidal melanoma were included in this retrospective study. The volumes of the optic nerve receiving doses of more than 7.5 or 12 Gy, respectively, were defined. Optic nerve circumference included in the 30%, 40%, 50%, or 80% isodose (ON%) and retina included in 30% or 40% were determined as quantal effects. Univariate and multivariate analyses were performed for clinical variables as well as probit analysis to define EDx (doses where a positive response is expected in x% of the cases). Median follow-up was 90.0 (interquartile range 69.0-98.0) months. Fifty-two (71%) and 49 (67%) patients developed radiation retinopathy and optic neuropathy (any grade). Age, length of follow-up and diabetes were significant parameters regarding retinopathy. Optic neuropathy was significantly influenced by age, length of follow-up, and ON30. The probability of optic neuropathy (any grade and grade ≥ 2) significantly increases with the dose (p ranges from 0.0126 to 0.0211). Treatment planning should aim at minimizing encompassing isodoses particularly in the low dose region, without compromising PTV coverage. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  13. Parotid gland tumors: a comparison of postoperative radiotherapy techniques using three dimensional (3-D) dose distributions and dose-volume histograms (DVH)

    International Nuclear Information System (INIS)

    Yaparpalvi, R.; Tyerech, S.K.; Boselli, L.R.; Fontenla, D.P.; Beitler, J.J.; Vikram, B.

    1996-01-01

    Purpose/Objective: To compare different treatment techniques for unilateral treatment of parotid gland tumors. Materials and Methods: Twenty patients previously treated postoperatively for parotid gland tumors were retrospectively reviewed. Average field size was 9 x 11 cm, average separation was 15.5 cm, and the average prescription depth was 4.5 cm. Using 3-D dose distributions, tissue inhomogeneity corrections, scatter integration (for photons) and pencil beam (for electrons) algorithms and DVH, nine treatment techniques were compared using a representative patient. The treatment techniques investigated were: [1] unilateral 6 MV photons. [2] unilateral 12 MeV electrons. [3] unilateral 16 MeV electrons. [4] a ipsilateral wedge pair technique using 6 MV photons and a 45-degree wedge. [5] a 3-field AP (wedged), PA (wedged) and lateral portal technique using 6 MV photons. [6] a mixed beam technique using 6 MV photons and 12 MeV electrons (1:4 weighting). [7] a mixed beam technique using 6 MV photons and 16 MeV electrons (1:4 weighting). [8] a mixed beam technique using 18 MV photons and 20 MeV electrons (2:3 weighting). [9] a mixed beam technique using 18 MV photons and 20 MeV electrons (1:1 weighting). Results: Using dose-volume histograms to evaluate the dose to the contralateral parotid gland, the percentage of contralateral parotid volume receiving ≥30% of the prescribed dose was 100% for techniques [1], [8] and [9], and <5% for techniques [2] through [7]. Evaluating the 'hottest' 5 cc of the ipsilateral mandible and temporal lobes, the hot spots were: 152% and 150% for technique [2], 132% and 130% for technique [6]. Comparing the exit doses, techniques [1] and [8] contributed to ≥50% of the prescribed dose to the contralateral mandible and the temporal lobes. Only techniques [2] and [6] kept the highest point doses to both the brain stem and the spinal cord below 50% of the prescribed dose. Conclusion: The single photon lateral field [1] and the mixed

  14. Occupational dose reduction at nuclear power plants: Annotated bibliography of selected readings in radiation protection and ALARA. Volume 7

    Energy Technology Data Exchange (ETDEWEB)

    Kaurin, D.G.; Khan, T.A.; Sullivan, S.G.; Baum, J.W. [Brookhaven National Lab., Upton, NY (United States)

    1993-07-01

    The ALARA Center at Brookhaven National Laboratory publishes a series of bibliographies of selected readings in radiation protection and ALARA in the continuing effort to collect and disseminate information on radiation dose reduction at nuclear power plants. This is volume 7 of the series. The abstracts in this bibliography were selected from proceedings of technical meetings and conferences, journals, research reports, and searches of the Energy Science and Technology database of the US Department of Energy. The subject material of these abstracts relates to radiation protection and dose reduction, and ranges from use of robotics to operational health physics, to water chemistry. Material on the design, planning, and management of nuclear power stations is included, as well as information on decommissioning and safe storage efforts. Volume 7 contains 293 abstract, an author index, and a subject index. The author index is specific for this volume. The subject index is cumulative and lists all abstract numbers from volumes 1 to 7. The numbers in boldface indicate the abstracts in this volume; the numbers not in boldface represent abstracts in previous volumes.

  15. Occupational dose reduction at nuclear power plants: Annotated bibliography of selected readings in radiation protection and ALARA. Volume 8

    International Nuclear Information System (INIS)

    Sullivan, S.G.; Khan, T.A.; Xie, J.W.

    1995-05-01

    The ALARA Center at Brookhaven National Laboratory publishes a series of bibliographies of selected readings in radiation protection and ALARA in a continuing effort to collect and disseminate information on radiation dose reduction at nuclear power plants. This volume 8 of the series. The abstracts in this bibliography were selected form proceedings of technical meetings and conference journals, research reports, and searches of the Energy Science and Technology database of the US Department of Energy. The subject material of these abstracts relates to the many aspects of radiation protection and dose reduction, and ranges form use of robotics, to operational health physics, to water chemistry. Material on the design, planning, and management of nuclear power stations is included, as well as information on decommissioning and safe storage efforts. Volume 8 contains 232 abstracts, an author index, and a subject index. The author index is specific for this volume. The subject index is cumulative and lists all abstract numbers from volumes 1 to 8. The numbers in boldface indicate the abstracts in this volume; the numbers not in boldface represent abstracts in previous volumes

  16. Occupational dose reduction at nuclear power plants: Annotated bibliography of selected readings in radiation protection and ALARA. Volume 8

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, S.G.; Khan, T.A.; Xie, J.W. [Brookhaven National Lab., Upton, NY (United States)

    1995-05-01

    The ALARA Center at Brookhaven National Laboratory publishes a series of bibliographies of selected readings in radiation protection and ALARA in a continuing effort to collect and disseminate information on radiation dose reduction at nuclear power plants. This volume 8 of the series. The abstracts in this bibliography were selected form proceedings of technical meetings and conference journals, research reports, and searches of the Energy Science and Technology database of the US Department of Energy. The subject material of these abstracts relates to the many aspects of radiation protection and dose reduction, and ranges form use of robotics, to operational health physics, to water chemistry. Material on the design, planning, and management of nuclear power stations is included, as well as information on decommissioning and safe storage efforts. Volume 8 contains 232 abstracts, an author index, and a subject index. The author index is specific for this volume. The subject index is cumulative and lists all abstract numbers from volumes 1 to 8. The numbers in boldface indicate the abstracts in this volume; the numbers not in boldface represent abstracts in previous volumes.

  17. Effect of oxygen on neuronal excitability measured by critical flicker fusion frequency is dose dependent.

    Science.gov (United States)

    Kot, Jacek; Winklewski, Pawel J; Sicko, Zdzislaw; Tkachenko, Yurii

    2015-01-01

    Reactive oxygen species are involved in the functional changes necessary for synaptic plasticity, memory, and cognitive function. It is far from clear whether the increased excitability, and which forms of neuronal excitability, should be considered a part of the learning process or, rather, cellular manifestation of neuronal oxygen poisoning. It is yet to be elucidated whether oxygen (O2)-induced learning and poisoning use the same or distinct cellular pathways. We hypothesized that O2-induced neuronal excitability might use the same or an intertwined signaling cascade as the poisoning cellular pathway. Eighty-one healthy, young males, mean age 27.7 ± 4.1 (SD) years, were exposed in the hyperbaric chamber to 0.7 atmosphere absolute (ATA) O2, 1.4 ATA O2, and 2.8 ATA O2. The critical flicker fusion frequency (CFFF), oxyhemoglobin saturation (SiO2), and heart rate (HR) were measured before exposure, after 30 min of oxygen breathing while still at pressure and then after exposure. Normobaric (0.7 ATA) O2 exposure did not affect CFFF and HR. Medium hyperbaric O2 exposure (1.4 ATA) decreased CFFF but HR remained unchanged. High hyperbaric O2 exposure (2.8 ATA) increased CFFF and diminished HR. SiO2 was similar in all investigated groups. A correlation between CFFF, HR, and SiO2 was observed only at low oxygen (0.7 ATA). The effect of O2 on neuronal excitability measured by CFFF in young healthy men was dose dependent: 0.7 ATA O2 did not affect CFFF; CFFF were significantly jeopardized at 1.4 ATA O2, while CFFF recovered at 2.8 ATA. With 2.8 ATA O2, the CFFF and oxygen poisoning transduction pathways seemed to be intertwined.

  18. Technical basis for radiological release of Grand Junction Office Building 2. Volume 2, dose assessment supporting data

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-07-01

    The second volume of the Grand Junction Office Action Program Technical Basis for Radiological Release of Grand Junction Office Building 2 report includes the data quality objectives (DQO), sampling plan, collected data, and analysis used to model future radiation doses to members of the public occupying Building 2 on the U.S. Department of Energy (DOE) Grand Junction Office (GJO) site. This volume was assembled by extracting relevant components of the Grand Junction Projects Office Remedial Action Project Building 2 Public Dose Evaluation (DOE 1996) and inserting recent additional data that was gathered and dose pathway modeling that was performed. The intent of this document is to provide all derived guidance decisions, assumptions, measured data, testing results, and pathway modeling software input and output data that supports the discussion and determinations presented in Volume 1 of this report. For constructive employment of this document, the reader is encouraged to closely follow Volume 1 for proper association with the segment of information being examined.

  19. Rectal toxicity after intensity modulated radiotherapy for prostate cancer: Which rectal dose volume constraints should we use?

    International Nuclear Information System (INIS)

    Fonteyne, Valérie; Ost, Piet; Vanpachtenbeke, Frank; Colman, Roos; Sadeghi, Simin; Villeirs, Geert; Decaestecker, Karel; De Meerleer, Gert

    2014-01-01

    Background: To define rectal dose volume constraints (DVC) to prevent ⩾grade2 late rectal toxicity (LRT) after intensity modulated radiotherapy (IMRT) for prostate cancer (PC). Material and methods: Six hundred thirty-seven PC patients were treated with primary (prostate median dose: 78 Gy) or postoperative (prostatic bed median dose: 74 Gy (adjuvant)–76 Gy (salvage)) IMRT while restricting the rectal dose to 76 Gy, 72 Gy and 74 Gy respectively. The impact of patient characteristics and rectal volume parameters on ⩾grade2 LRT was determined. DVC were defined to estimate the 5% and 10% risk of developing ⩾grade2 LRT. Results: The 5-year probability of being free from ⩾grade2 LRT, non-rectal blood loss and persisting symptoms is 88.8% (95% CI: 85.8–91.1%), 93.4% (95% CI: 91.0–95.1%) and 94.3% (95% CI: 92.0–95.9%) respectively. There was no correlation with patient characteristics. All volume parameters, except rectal volume receiving ⩾70 Gy (R70), were significantly correlated with ⩾grade2 LRT. To avoid 10% and 5% risk of ⩾grade2 LRT following DVC were derived: R40, R50, R60 and R65 <64–35%, 52–22%, 38–14% and 5% respectively. Conclusion: Applying existing rectal volume constraints resulted in a 5-year estimated risk of developing late ⩾grade2 LRT of 11.2%. New rectal DVC for primary and postoperative IMRT planning of PC patients are proposed. A prospective evaluation is needed

  20. The Dose-Volume Relationship of Small Bowel Irradiation and Acute Grade 3 Diarrhea During Chemoradiotherapy for Rectal Cancer

    International Nuclear Information System (INIS)

    Robertson, John M.; Lockman, David; Yan Di; Wallace, Michelle

    2008-01-01

    Purpose: Previous work has found a highly significant relationship between the irradiated small-bowel volume and development of Grade 3 small-bowel toxicity in patients with rectal cancer. This study tested the previously defined parameters in a much larger group of patients. Methods and Materials: A total of 96 consecutive patients receiving pelvic radiation therapy for rectal cancer had treatment planning computed tomographic scans with small-bowel contrast that allowed the small bowel to be outlined with calculation of a small-bowel dose-volume histogram for the initial intended pelvic treatment to 45 Gy. Patients with at least one parameter above the previously determined dose-volume parameters were considered high risk, whereas those with all parameters below these levels were low risk. The grade of diarrhea and presence of liquid stool was determined prospectively. Results: There was a highly significant association with small-bowel dose-volume and Grade 3 diarrhea (p ≤ 0.008). The high-risk and low-risk parameters were predictive with Grade 3 diarrhea in 16 of 51 high-risk patients and in 4 of 45 low-risk patients (p = 0.01). Patients who had undergone irradiation preoperatively had a lower incidence of Grade 3 diarrhea than those treated postoperatively (18% vs. 28%; p = 0.31); however, the predictive ability of the high-risk/low-risk parameters was better for preoperatively (p = 0.03) than for postoperatively treated patients (p = 0.15). Revised risk parameters were derived that improved the overall predictive ability (p = 0.004). Conclusions: The highly significant dose-volume relationship and validity of the high-risk and low-risk parameters were confirmed in a large group of patients. The risk parameters provided better modeling for the preoperative patients than for the postoperative patients

  1. Outcomes of visual acuity in carbon ion radiotherapy: Analysis of dose-volume histograms and prognostic factors

    International Nuclear Information System (INIS)

    Hasegawa, Azusa; Mizoe, Jun-etsu; Mizota, Atsushi; Tsujii, Hirohiko

    2006-01-01

    Purpose: To analyze the tolerance dose for retention of visual acuity in patients with head-and-neck tumors treated with carbon ion radiotherapy. Methods and Materials: From June 1994 to March 2000, 163 patients with tumors in the head and neck or skull base region were treated with carbon ion radiotherapy. Analysis was performed on 54 optic nerves (ONs) corresponding to 30 patients whose ONs had been included in the irradiated volume. These patients showed no evidence of visual impairment due to other factors and had a follow-up period of >4 years. All patients had been informed of the possibility of visual impairment before treatment. We evaluated the dose-complication probability and the prognostic factors for the retention of visual acuity in carbon ion radiotherapy, using dose-volume histograms and multivariate analysis. Results: The median age of 30 patients (14 men, 16 women) was 57.2 years. Median prescribed total dose was 56.0 gray equivalents (GyE) at 3.0-4.0 GyE per fraction per day (range, 48-64 GyE; 16-18 fractions; 4-6 weeks). Of 54 ONs that were analyzed, 35 had been irradiated with max ]) resulting in no visual loss. Conversely, 11 of the 19 ONs (58%) irradiated with >57 GyE (D max ) suffered a decrease of visual acuity. In all of these cases, the ONs had been involved in the tumor before carbon ion radiotherapy. In the multivariate analysis, a dose of 20% of the volume of the ON (D 2 ) was significantly associated with visual loss. Conclusions: The occurrence of visual loss seems to be correlated with a delivery of >60 GyE to 20% of the volume of the ON

  2. Dose-volume histogram parameters of high-dose-rate brachytherapy for Stage I-II cervical cancer (≤4cm) arising from a small-sized uterus treated with a point A dose-reduced plan

    International Nuclear Information System (INIS)

    Nakagawa, Akiko; Noda, Shin-ei; Kubo, Nobuteru; Kuwako, Keiko; Nakano, Takashi; Ohno, Tatsuya; Saitoh, Jun-ichi

    2014-01-01

    We investigated the rectal dose-sparing effect and tumor control of a point A dose-reduced plan in patients with Stage I-II cervical cancer (≤4 cm) arising from a small-sized uterus. Between October 2008 and August 2011, 19 patients with Stage I-II cervical cancer (≤4 cm) were treated with external beam radiotherapy (EBRT) for the pelvis and CT-guided brachytherapy. Seven patients were treated with brachytherapy with standard loading of source-dwell positions and a fraction dose of 6 Gy at point A (conventional brachy-plan). The other 12 patients with a small uterus close to the rectum or small intestine were treated with brachytherapy with a point A dose-reduction to match D2cc of the rectum and <6 Gy as the dose constraint ('point A dose-reduced plan') instead of the 6-Gy plan at point A ('tentative 6-Gy plan'). The total doses from EBRT and brachytherapy were added up and normalized to a biological equivalent dose of 2 Gy per fraction (EQD2). The median doses to the high-risk clinical target volume (HR-CTV) D90 in the conventional brachy-plan, tentative 6-Gy plan and point A dose-reduced plan were 62 GyEQD2, 80 GyEQD2 and 64 GyEQD2, respectively. The median doses of rectal D2cc in the corresponding three plans were 42 GyEQD2, 62 GyEQD2 and 51 GyEQD2, respectively. With a median follow-up period of 35 months, three patients developed Grade-1 late rectal complications and no patients developed local recurrence. Our preliminary results suggested that CT-guided brachytherapy using an individualized point A dose-reduced plan might be useful for reducing late rectal complications while maintaining primary tumor control. (author)

  3. Comparative analysis of dose-volume histograms between 3D conformal and conventional non-conformal radiotherapy planning for prostate cancer

    International Nuclear Information System (INIS)

    Feitosa, Silvia Moreira; Giordani, Adelmo Jose; Dias, Rodrigo Sousa; Segreto, Helena Regina Comodo; Segreto, Roberto Araujo

    2009-01-01

    Objective: The present study was aimed at comparing conformal and non-conformal radiotherapy plans designed for patients with prostate cancer, by analyzing radiation doses in target volumes and organs at risk. Materials and methods: Radiotherapy plans for 40 patients with prostate cancer were analyzed. Conformal, conformal isocentric and non-conformal plans utilizing the source-surface distance were simulated for each of the patients for comparison of radiation dose in target volumes and organs at risk. For comparison purposes, dose-volume histograms for target volumes and organs at risk were analyzed. Results: Median doses were significantly lower in the conformal planning, with 25%, 40% and 60% volumes in the rectum and 30% and 60% in the bladder. The median doses were significantly lower in the conformal planning analyzing the right and left coxofemoral joints. Maximum, mean and median doses in the clinical target volume and in the planned target volume were significantly higher in the conformal planning. Conclusion: The present study has demonstrated that the conformal radiotherapy planning for prostate cancer allows the delivery of higher doses to the target volume and lower doses to adjacent healthy tissues. (author)

  4. Assessment of the effective supplementary doses for people belonging to a critical group placed nearby an uranium mining zone

    International Nuclear Information System (INIS)

    Aurelian, Florian; Popescu, Mihai; Georgescu, Dan

    2008-01-01

    Full text: The paper presents a case study concerning the impact on environment and population of a exploration uranium mining area. The paper is structured on three levels and presents: First stage will consist of the investigation and characterization of the sources, respectively the transfer pathways: terrestrial, aerial and aquatic ones followed by the assessment of the effective supplementary doses received by the people of population through all the transfer pathways based on some scenarios according to which their presence was permanent or temporary. Second stage concerns the assessment of the supplementary effective doses for the working staff during the caring out the closing workings. There are references concerning the monitoring 'of rehabilitation' during the time when the disaffection workings are ongoing beside the survey of the professional exposed people and the calculation of the supplementary doses for people of population and the ones belonging to the critical group during the disaffection time. Within the third stage framework there are calculated, described and discussed the individual and collective effective doses for people belonging to the population and to the critical groups, which it is expected to be recorded after the disaffection works cessation. The last part of the paper focuses on the long-term miniaturization of the environmental factors following the disaffection works conclusion and on the long-term evolution of the supplementary doses as well. (author)

  5. Acute small bowel toxicity and preoperative chemoradiotherapy for rectal cancer: Investigating dose-volume relationships and role for inverse planning

    International Nuclear Information System (INIS)

    Tho, Lye Mun; Glegg, Martin; Paterson, Jennifer; Yap, Christina; MacLeod, Alice; McCabe, Marie; McDonald, Alexander C.

    2006-01-01

    Purpose: The relationship between volume of irradiated small bowel (VSB) and acute toxicity in rectal cancer radiotherapy is poorly quantified, particularly in patients receiving concurrent preoperative chemoradiotherapy. Using treatment planning data, we studied a series of such patients. Methods and Materials: Details of 41 patients with locally advanced rectal cancer were reviewed. All received 45 Gy in 25 fractions over 5 weeks, 3-4 fields three-dimensional conformal radiotherapy with daily 5-fluorouracil and folinic acid during Weeks 1 and 5. Toxicity was assessed prospectively in a weekly clinic. Using computed tomography planning software, the VSB was determined at 5 Gy dose intervals (V 5 , V 1 , etc.). Eight patients with maximal VSB had dosimetry and radiobiological modeling outcomes compared between inverse and conformal three-dimensional planning. Results: VSB correlated strongly with diarrheal severity at every dose level (p 5 and V 15 . Conclusions: A strong dose-volume relationship exists between VSB and acute diarrhea at all dose levels during preoperative chemoradiotherapy. Our constructed model may be useful in predicting toxicity, and this has been derived without the confounding influence of surgical excision on bowel function. Inverse planning can reduce calculated dose to small bowel and late NTCP, and its clinical role warrants further investigation

  6. Sparing Healthy Tissue and Increasing Tumor Dose Using Bayesian Modeling of Geometric Uncertainties for Planning Target Volume Personalization

    Energy Technology Data Exchange (ETDEWEB)

    Herschtal, Alan, E-mail: Alan.Herschtal@petermac.org [Department of Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, Melbourne (Australia); Faculty of Health, Arts and Design, Swinburne University of Technology, Melbourne (Australia); Te Marvelde, Luc [Department of Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, Melbourne (Australia); Mengersen, Kerrie [School of Mathematical Sciences, Science and Engineering Faculty, Queensland University of Technology, Brisbane (Australia); Foroudi, Farshad [Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne (Australia); The Sir Peter MacCallum Department of Oncology, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne (Australia); Eade, Thomas [Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St. Leonards, Sydney (Australia); Northern Clinical School, University of Sydney (Australia); Pham, Daniel [Department of Radiation Therapy, Peter MacCallum Cancer Centre, Melbourne (Australia); Caine, Hannah [Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St. Leonards, Sydney (Australia); Kron, Tomas [The Sir Peter MacCallum Department of Oncology, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne (Australia); Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne (Australia)

    2015-06-01

    Objective: To develop a mathematical tool that can update a patient's planning target volume (PTV) partway through a course of radiation therapy to more precisely target the tumor for the remainder of treatment and reduce dose to surrounding healthy tissue. Methods and Materials: Daily on-board imaging was used to collect large datasets of displacements for patients undergoing external beam radiation therapy for solid tumors. Bayesian statistical modeling of these geometric uncertainties was used to optimally trade off between displacement data collected from previously treated patients and the progressively accumulating data from a patient currently partway through treatment, to optimally predict future displacements for that patient. These predictions were used to update the PTV position and margin width for the remainder of treatment, such that the clinical target volume (CTV) was more precisely targeted. Results: Software simulation of dose to CTV and normal tissue for 2 real prostate displacement datasets consisting of 146 and 290 patients treated with a minimum of 30 fractions each showed that re-evaluating the PTV position and margin width after 8 treatment fractions reduced healthy tissue dose by 19% and 17%, respectively, while maintaining CTV dose. Conclusion: Incorporating patient-specific displacement patterns from early in a course of treatment allows PTV adaptation for the remainder of treatment. This substantially reduces the dose to healthy tissues and thus can reduce radiation therapy–induced toxicities, improving patient outcomes.

  7. Dose-volume and biological-model based comparison between helical tomotherapy and (inverse-planned) IMAT for prostate tumours

    International Nuclear Information System (INIS)

    Iori, Mauro; Cattaneo, Giovanni Mauro; Cagni, Elisabetta; Fiorino, Claudio; Borasi, Gianni; Riccardo, Calandrino; Iotti, Cinzia; Fazio, Ferruccio; Nahum, Alan E.

    2008-01-01

    Background and purpose: Helical tomotherapy (HT) and intensity-modulated arc therapy (IMAT) are two arc-based approaches to the delivery of intensity-modulated radiotherapy (IMRT). Through plan comparisons we have investigated the potential of IMAT, both with constant (conventional or IMAT-C) and variable (non-conventional or IMAT-NC, a theoretical exercise) dose-rate, to serve as an alternative to helical tomotherapy. Materials and methods: Six patients with prostate tumours treated by HT with a moderately hypo-fractionated protocol, involving a simultaneous integrated boost, were re-planned as IMAT treatments. A method for IMAT inverse-planning using a commercial module for static IMRT combined with a multi-leaf collimator (MLC) arc-sequencing was developed. IMAT plans were compared to HT plans in terms of dose statistics and radiobiological indices. Results: Concerning the planning target volume (PTV), the mean doses for all PTVs were similar for HT and IMAT-C plans with minimum dose, target coverage, equivalent uniform dose (EUD) and tumour control probability (TCP) values being generally higher for HT; maximum dose and degree of heterogeneity were instead higher for IMAT-C. In relation to organs at risk, mean doses and normal tissue complication probability (NTCP) values were similar between the two modalities, except for the penile bulb where IMAT was significantly better. Re-normalizing all plans to the same rectal toxicity (NTCP = 5%), the HT modality yielded higher TCP than IMAT-C but there was no significant difference between HT and IMAT-NC. The integral dose with HT was higher than that for IMAT. Conclusions: with regards to the plan analysis, the HT is superior to IMAT-C in terms of target coverage and dose homogeneity within the PTV. Introducing dose-rate variation during arc-rotation, not deliverable with current linac technology, the simulations result in comparable plan indices between (IMAT-NC) and HT

  8. Analytical evaluation of dose measurement of critical accident at SILENE (Contract research)

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Takemi; Tonoike, Kotaro; Miyoshi, Yoshinori [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    Institute for Radioprotection and Nuclear Safety (IRSN) and the OECD Nuclear Energy Agency (NEA) jointly organized SILENE Accident Dosimetry Intercomparison Exercise to intercompare the dose measurement systems of participating countries. Each participating country carried out dose measurements in the same irradiation field, and the measurement results were mutually compared. The authors participated in the exercise to measure the doses of gamma rays and neutron from SILENE by using thermoluminescence dosimeters (TLD's) and an alanine dosimeter. In this examination, the authors derived evaluation formulae for obtaining a tissue-absorbed dose from measured value (ambient dose equivalent) of TLD for neutron. We reported the tissue-absorbed dose computed using this evaluation formula to OECD/NEA. TLD's for neutron were irradiated in the TRACY facility to verify the evaluation formulae. The results of TLD's were compared with the calculations of MCNP and measurements with alanine dose meter. We found that the ratio of the dose by the evaluation formula to the measured value by the alanine dosimeter was 0.94 and the formula agreed within 6%. From examination of this TRACY, we can conclude that the value reported to OECD/NEA has equivalent accuracy. (author)

  9. Effect of various methods for rectum delineation on relative and absolute dose-volume histograms for prostate IMRT treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    Kusumoto, Chiaki [Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka (Japan); Ohira, Shingo [Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka (Japan); Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita (Japan); Miyazaki, Masayoshi [Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka (Japan); Ueda, Yoshihiro [Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka (Japan); Department of Radiation Oncology, Graduate School of Medicine, Osaka University, Suita (Japan); Isono, Masaru [Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka (Japan); Teshima, Teruki, E-mail: teshima-te@mc.pref.osaka.jp [Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka (Japan)

    2016-07-01

    Several reports have dealt with correlations of late rectal toxicity with rectal dose-volume histograms (DVHs) for high dose levels. There are 2 techniques to assess rectal volume for reception of a specific dose: relative-DVH (R-DVH, %) that indicates relative volume for a vertical axis, and absolute-DVH (A-DVH, cc) with its vertical axis showing absolute volume of the rectum. The parameters of DVH vary depending on the rectum delineation method, but the literature does not present any standardization of such methods. The aim of the present study was to evaluate the effects of different delineation methods on rectal DVHs. The enrollment for this study comprised 28 patients with high-risk localized prostate cancer, who had undergone intensity-modulated radiation therapy (IMRT) with the prescription dose of 78 Gy. The rectum was contoured with 4 different methods using 2 lengths, short (Sh) and long (Lg), and 2 cross sections, rectum (Rec) and rectal wall (Rw). Sh means the length from 1 cm above the seminal vesicles to 1 cm below the prostate and Lg the length from the rectosigmoid junction to the anus. Rec represents the entire rectal volume including the rectal contents and Rw the rectal volume of the area with a wall thickness of 4 mm. We compared dose-volume parameters by using 4 rectal contour methods for the same plan with the R-DVHs as well as the A-DVHs. For the high dose levels, the R-DVH parameters varied widely. The mean of V{sub 70} for Sh-Rw was the highest (19.4%) and nearly twice as high as that for Lg-Rec (10.4%). On the contrary, only small variations were observed in the A-DVH parameters (4.3, 4.3, 5.5, and 5.5 cc for Sh-Rw, Lg-Rw, Sh-Rec, and Lg-Rec, respectively). As for R-DVHs, the parameters of V{sub 70} varied depending on the rectal lengths (Sh-Rec vs Lg-Rec: R = 0.76; Sh-Rw vs Lg-Rw: R = 0.85) and cross sections (Sh-Rec vs Sh-Rw: R = 0.49; Lg-Rec vs Lg-Rw: R = 0.65). For A-DVHs, however, the parameters of Sh rectal A-DVHs hardly changed

  10. Effect of geometrical optimization on the treatment volumes and the dose homogeneity of biplane interstitial brachytherapy implants

    International Nuclear Information System (INIS)

    Anacak, Yavuz; Esassolak, Mustafa; Aydin, Ayhan; Aras, Arif; Olacak, Ibrahim; Haydaroglu, Ayfer

    1997-01-01

    Background and purpose: The isodose distributions of HDR stepping source brachytherapy implants can be modified by changing dwell times and this procedure is called optimization. The purpose of this study is to evaluate the effect of geometrical optimization on the brachytherapy volumes and the dose homogeneity inside the implant and to compare them with non-optimized counterparts. Material and methods: A set of biplane breast implants consisting of 84 different configurations have been digitized by the planning computer and volumetric analysis was performed for both non-optimized and geometrically optimized implants. Treated length (T L ), treated volume (V 100 ), irradiated volume (V 50 ), overdose volume (V 200 ) and quality index (QI) have been calculated for every non-optimized implant and compared to its corresponding geometrically optimized implant having a similar configuration and covering the same target length. Results: The mean T L was 74.48% of the active length (A L ) for non-optimized implants and was 91.87% for optimized implants (P 50 /V 100 value was 2.71 for non-optimized implants and 2.65 for optimized implants (P 200 /V 100 value was 0.09 for non-optimized implants and 0.10 for optimized implants (P < 0.001). Conclusions: By performing geometrical optimization it is possible to implant shorter needles for a given tumour to adequately cover the target volume with the reference isodose and thus surgical damage is reduced. The amount of healthy tissues outside the target receiving considerable radiation is significantly reduced due to the decrease in irradiated volume. Dose homogeneity inside the implant is significantly improved. Although there is a slight increase of overdose volume inside the implant, this increase is considered to be negligible in clinical applications

  11. Dose escalation to high-risk sub-volumes based on non-invasive imaging of hypoxia and glycolytic activity in canine solid tumors

    DEFF Research Database (Denmark)

    Clausen, Malene M.; Hansen, Anders Elias; af Rosenschold, Per Munck

    2013-01-01

    defined by a threshold based method. FDG sub-volumes were delineated at 40% (FDG40) and 50% (FDG50) of SUVmax. The size of sub-volumes, intersection and biological target volume (BTV) were measured in a treatment planning software. By varying the average dose prescription to the tumor from 66 to 85 Gy...

  12. SU-E-T-546: Use of Implant Volume for Quality Assurance of Low Dose Rate Brachytherapy Treatment Plans

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, D; Kolar, M [Radiation Oncology, Cleveland Clinic Foundation, Cleveland, OH (United States)

    2014-06-01

    Purpose: To analyze the application of volume implant (V100) data as a method for a global check of low dose rate (LDR) brachytherapy plans. Methods: Treatment plans for 335 consecutive patients undergoing permanent seed implants for prostate cancer and for 113 patients treated with plaque therapy for ocular melanoma were analyzed. Plaques used were 54 COMS (10 to 20 mm, notched and regular) and 59 Eye Physics EP917s with variable loading. Plots of treatment time x implanted activity per unit dose versus v100 ^.667 were made. V100 values were obtained using dose volume histograms calculated by the treatment planning systems (Variseed 8.02 and Plaque Simulator 5.4). Four different physicists were involved in planning the prostate seed cases; two physicists for the eye plaques. Results: Since the time and dose for the prostate cases did not vary, a plot of implanted activity vs V100 ^.667 was made. A linear fit with no intercept had an r{sup 2} = 0.978; more than 94% of the actual activities fell within 5% of the activities calculated from the linear fit. The greatest deviations were in cases where the implant volumes were large (> 100 cc). Both COMS and EP917 plaque linear fits were good (r{sup 2} = .967 and .957); the largest deviations were seen for large volumes. Conclusions: The method outlined here is effective for checking planning consistency and quality assurance of two types of LDR brachytherapy treatment plans (temporary and permanent). A spreadsheet for the calculations enables a quick check of the plan in situations were time is short (e.g. OR-based prostate planning)

  13. Change in volumes and radiation doses of parotid and submandibular glands during intensity modulated radiation therapy (IMRT) for nasopharyngeal carcinoma

    OpenAIRE

    Ho, PPY; Kwong, DLW; Au, GKH; Leung, TW; Lee, V; Ng, SCY

    2011-01-01

    OBJECTIVES: To investigate the changes in volumes and radiation doses to parotid and submandibular glands during IMRT for nasopharyngeal carcinoma in an attempt to justify re-planning in the mid-course of IMRT to minimize radiation-induced xerostomia. MATERIALS AND METHODS: 33 consecutive patients with stage III to stage IVB nasopharyngeal carcinoma (AJCC Staging Manual 6th Edition) who received concurrent chemoradiation were included in this study. Computed tomography (CT) scans were perform...

  14. RADIATION MONITORING THE INDUSTRIAL NUCLEAR EXPLOSION SITES AND EVALUATION OF THE DOSES TO THE CRITICAL GROUPS OF POPULATION

    Directory of Open Access Journals (Sweden)

    V. P. Ramzaev

    2010-01-01

    Full Text Available The paper outlines the key elements of the radiation monitoring system at the sites of industrial nuclear explosions in the Russian Federation. The proposed recommendations describe sampling and measurements procedures, registration of the results and their cartographic presentation. The algorithm and formulas for calculating the doses to the critical groups of population are given. The recommendations are proposed, first of all, for practical application by the regional units of the State Sanitary Inspection.

  15. Safety analysis for the Abadia de Goias repository: alternative evaluation of the ingestion dose rate critical distance

    International Nuclear Information System (INIS)

    Martin Alves, A.S. de; Passos, E.M. dos

    1995-01-01

    An alternative calculation of the ingestion dose rate critical distance due to a hypothetical release of Cs-137 from the structure of the Repository of Abadia de Goias is presented. The release pathway considers the repository - groundwater region - well - and food chain. The main adopted modification comparing to the previous work is the inclusion of the convective and molecular diffusion terms in the radionuclide transport equation in addition to the radioactive decay term. (author). 6 refs, 1 tab

  16. Radiation-Induced Rib Fractures After Hypofractionated Stereotactic Body Radiation Therapy: Risk Factors and Dose-Volume Relationship

    Energy Technology Data Exchange (ETDEWEB)

    Asai, Kaori [Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan); Shioyama, Yoshiyuki, E-mail: shioyama@radiol.med.kyushu-u.ac.jp [Department of Heavy Particle Therapy and Radiation Oncology, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan); Nakamura, Katsumasa; Sasaki, Tomonari; Ohga, Saiji; Nonoshita, Takeshi [Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan); Yoshitake, Tadamasa [Department of Heavy Particle Therapy and Radiation Oncology, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan); Ohnishi, Kayoko [Department of Radiology, National Center for Global Health and Medicine, Tokyo (Japan); Terashima, Kotaro; Matsumoto, Keiji [Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan); Hirata, Hideki [Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan); Honda, Hiroshi [Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan)

    2012-11-01

    Purpose: The purpose of this study was to clarify the incidence, the clinical risk factors, and the dose-volume relationship of radiation-induced rib fracture (RIRF) after hypofractionated stereotactic body radiation therapy (SBRT). Methods and Materials: One hundred sixteen patients treated with SBRT for primary or metastatic lung cancer at our institution, with at least 6 months of follow-up and no previous overlapping radiation exposure, were included in this study. To determine the clinical risk factors associated with RIRF, correlations between the incidence of RIRF and the variables, including age, sex, diagnosis, gross tumor volume diameter, rib-tumor distance, and use of steroid administration, were analyzed. Dose-volume histogram analysis was also conducted. Regarding the maximum dose, V10, V20, V30, and V40 of the rib, and the incidences of RIRF were compared between the two groups divided by the cutoff value determined by the receiver operating characteristic curves. Results: One hundred sixteen patients and 374 ribs met the inclusion criteria. Among the 116 patients, 28 patients (46 ribs) experienced RIRF. The estimated incidence of rib fracture was 37.7% at 3 years. Limited distance from the rib to the tumor (<2.0 cm) was the only significant risk factor for RIRF (p = 0.0001). Among the dosimetric parameters used for receiver operating characteristic analysis, the maximum dose showed the highest area under the curve. The 3-year estimated risk of RIRF and the determined cutoff value were 45.8% vs. 1.4% (maximum dose, {>=}42.4 Gy or less), 51.6% vs. 2.0% (V40, {>=}0.29 cm{sup 3} or less), 45.8% vs. 2.2% (V30, {>=}1.35 cm{sup 3} or less), 42.0% vs. 8.5% (V20, {>=}3.62 cm{sup 3} or less), or 25.9% vs. 10.5% (V10, {>=}5.03 cm{sup 3} or less). Conclusions: The incidence of RIRF after hypofractionated SBRT is relatively high. The maximum dose and high-dose volume are strongly correlated with RIRF.

  17. Final Technical Report. A critical evaluation of patent doses in screening mammography

    International Nuclear Information System (INIS)

    Hintenlang, David E.

    2004-01-01

    This project was designed to develop tools that would permit an accurate assessment of the patient doses that are received in screening mammography, and to subsequently demonstrate those tools to perform an objective evaluation of patient doses. The project also provides an educational component through the integration of multiple aspects of applied radiological engineering to provide students with realistic applications of many of the theoretical principles that are studied as part of their graduate curriculum

  18. Consequences of additional use of PET information for target volume delineation and radiotherapy dose distribution for esophageal cancer

    International Nuclear Information System (INIS)

    Muijs, Christina T.; Schreurs, Liesbeth M.; Busz, Dianne M.; Beukema, Jannet C.; Borden, Arnout J. van der; Pruim, Jan; Van der Jagt, Eric J.; Plukker, John Th.; Langendijk, Johannes A.

    2009-01-01

    Background and purpose: To determine the consequences of target volume (TV) modifications, based on the additional use of PET information, on radiation planning, assuming PET/CT-imaging represents the true extent of the tumour. Materials and methods: For 21 patients with esophageal cancer, two separate TV's were retrospectively defined based on CT (CT-TV) and co-registered PET/CT images (PET/CT-TV). Two 3D-CRT plans (prescribed dose 50.4 Gy) were constructed to cover the corresponding TV's. Subsequently, these plans were compared for target coverage, normal tissue dose-volume histograms and the corresponding normal tissue complication probability (NTCP) values. Results: The addition of PET led to the modification of CT-TV with at least 10% in 12 of 21 patients (57%) (reduction in 9, enlargement in 3). PET/CT-TV was inadequately covered by the CT-based treatment plan in 8 patients (36%). Treatment plan modifications resulted in significant changes (p < 0.05) in dose distributions to heart and lungs. Corresponding changes in NTCP values ranged from -3% to +2% for radiation pneumonitis and from -0.2% to +1.2% for cardiac mortality. Conclusions: This study demonstrated that TV's based on CT might exclude PET-avid disease. Consequences are under dosing and thereby possibly ineffective treatment. Moreover, the addition of PET in radiation planning might result in clinical important changes in NTCP.

  19. Applicability of ambient dose equivalent H*(d) in mixed radiation fields - a critical discussion

    International Nuclear Information System (INIS)

    Hajek, M.; Vana, N.

    2004-01-01

    For purposes of routine radiation protection, it is desirable to characterize the potential irradiation of individuals in terms of a single dose equivalent quantity that would exist in a phantom approximating the human body. The phantom of choice is the ICRU sphere made of 30 cm diameter tissue-equivalent plastic with a density of 1 g.cm-3 and a mass composition of 76.2 % O, 11.1 % C, 10.1 % H and 2.6 % N. Ambient dose equivalent, H*(d), was defined in ICRU report 51 as the dose equivalent that would be produced by an expanded and aligned radiation field at a depth d in the ICRU sphere. The recommended reference depths are 10 mm for strongly penetrating radiation and 0.07 mm for weakly penetrating radiation, respectively. As an operational quantity in radiation protection, H*(d) shall serve as a conservative and directly measurable estimate of protection quantities, e.g. effective dose E, which in turn are intended to give an indication of the risk associated with radiation exposure. The situation attains increased complexity in radiation environments being composed of a variety of charged and uncharged particles in a broad energetic spectrum. Radiation fields of similarly complex nature are, for example, encountered onboard aircraft and in space. Dose equivalent was assessed as a function of depth in quasi tissue-equivalent spheres by means of thermoluminescent dosemeters evaluated according to the high-temperature ratio (HTR) method. The presented experiments were performed both onboard aircraft and the Russian space station Mir. As a result of interaction processes within the phantom body, the incident primary spectrum may be significantly modified with increasing depth. For the radiation field at aviation altitudes we found the maximum of dose equivalent in a depth of 60 mm which conflicts with the 10 mm value recommended by ICRU. Contrary, for the space radiation environment the maximum dose equivalent was found at the surface of the sphere. This suggests that

  20. Applicability of Ambient Dose Equivalent H (d) in Mixed Radiation Fields - A Critical Discussion

    International Nuclear Information System (INIS)

    Vana, R.; Hajek, M.; Bergerm, T.

    2004-01-01

    For purposes of routine radiation protection, it is desirable to characterize the potential irradiation of individuals in terms of a single dose equivalent quantity that would exist in a phantom approximating the human body. The phantom of choice is the ICRU sphere made of 30 cm diameter tissue-equivalent plastic with a density of 1 g/cm3 and a mass composition of 76.2% O, 11.1% C, 10.1% H and 2.6% N. Ambient dose equivalent, H(d), was defined in ICRU report 51 as the dose equivalent that would be produced by an expanded and aligned radiation field at a depth d in the ICRU sphere. The recommended reference depths are 10 mm for strongly penetrating radiation and 0.07 mm for weakly penetrating radiation, respectively. As an operational quantity in radiation protection, H(d) shall serve as a conservative and directly measurable estimate of protection quantities, e.g. effective dose E, which in turn are intended to give an indication of the risk associated with radiation exposure. The situation attains increased complexity in radiation environments being composed of a variety of charged and uncharged particles in a broad energetic spectrum. Radiation fields of similarly complex nature are, for example, encountered onboard aircraft and in space. Dose equivalent was assessed as a function of depth in quasi tissue-equivalent spheres by means of thermoluminescent dosemeters evaluated according to the high-temperature ratio (HTR) method. The presented experiments were performed both onboard aircraft and the Russian space station Mir. As a result of interaction processes within the phantom body, the incident primary spectrum may be significantly modified with increasing depth. For the radiation field at aviation altitudes we found the maximum of dose equivalent in a depth of 60 mm which conflicts with the 10 mm value recommended by ICRU. Contrary, for the space radiation environment the maximum dose equivalent was found at the surface of the sphere. This suggests that skin

  1. Population dose commitments due to radioactive releases from nuclear power plant sites in 1982. Volume 4

    International Nuclear Information System (INIS)

    Baker, D.A.; Peloquin, R.A.

    1986-06-01

    Population radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1982. Fifty-year dose commitments from a one-year exposure were calculated from both liquid and atmospheric releases for four population groups (infant, child, teen-ager and adult) residing between 2 and 80 km from each of 51 sites. This report tabulates the results of these calculations, showing the dose commitments for both liquid and airborne pathways for each age group and organ. Also included for each site is a histogram showing the fraction of the total population within 2 to 80 km around each site receiving various average dose commitments from the airborne pathways. The total dose commitments from both liquid and airborne pathways ranged from a high of 30 person-rem to a low of 0.007 person-rem for the sites with plants operating throughout the year with an arithmetic mean of 3 person-rem. The total population dose for all sites was estimated at 130 person-rem for the 100 million people considered at risk. The average individual dose commitment from all pathways on a site basis ranged from a low of 6 x 10 -7 mrem to a high of 0.06 mrem. No attempt was made in this study to determine the maximum dose commitment received by any one individual from the radionuclides released at any of the sites

  2. Changes in pharyngeal constrictor volumes during head and neck radiation therapy: Implications for dose delivery

    Directory of Open Access Journals (Sweden)

    Akila Kumarasiri

    2017-01-01

    Conclusion: The patients underwent considerable anatomical changes to PCM during H and N RT. However, the resultant increase in dose to PCM was minor to moderate. PCM thickness measured at C3 level is a good predictor for the mean dose increase to PCM.

  3. SU-F-T-254: Dose Volume Histogram (DVH) Analysis of Breath Hold Vs Free Breathing Techniques for Esophageal Tumors

    Energy Technology Data Exchange (ETDEWEB)

    Badkul, R; Doke, K; Pokhrel, D; Aguilera, N; Lominska, C [University of Kansas Medical Center, Kansas City, KS (United States)

    2016-06-15

    Purpose: Lung and heart doses and associated toxicity are of concern in radiotherapy for esophageal cancer. This study evaluates the dosimetry of deep-inspiration-breath-hold (DIBH) technique as compared to freebreathing( FB) using 3D-conformal treatment(3D-CRT) of esophageal cancer. Methods: Eight patients were planned with FB and DIBH CT scans. DIBH scans were acquired using Varian RPM system. FB and DIBH CTs were contoured per RTOG-1010 to create the planning target volume(PTV) as well as organs at risk volumes(OAR). Two sets of gross target volumes(GTV) with 5cm length were contoured for each patient: proximal at the level of the carina and distal at the level of gastroesophageal junction and were enlarged with appropriate margin to generate Clinical Target Volume and PTV. 3D-CRT plans were created on Eclipse planning system for 45Gy to cover 95% of PTV in 25 fractions for both proximal and distal tumors on FB and DIBH scans. For distal tumors celiac nodes were covered electively. DVH parameters for lung and heart OARs were generated and analyzed. Results: All DIBH DVH parameters were normalized to FB plan values. Average of heart-mean and heart-V40 was 0.70 and 0.66 for proximal lesions. For distal lesions ratios were 1.21 and 2.22 respectively. For DIBH total lung volume increased by 2.43 times versus FB scan. Average of lung-mean, V30, V20, V10, V5 are 0.82, 0.92, 0.76, 0.77 and 0.79 for proximal lesions and 1.17,0.66,0.87,0.93 and 1.03 for distal lesions. Heart doses were lower for breath-hold proximal lesions but higher for distal lesions as compared to free-breathing plans. Lung doses were lower for both proximal and distal breath-hold lesions except mean lung dose and V5 for distal lesions. Conclusion: This study showed improvement of OAR doses for esophageal lesions at mid-thoracic level utilizing DIBH vs FB technique but did not show consistent OAR sparing with DIBH for distal lesions.

  4. SU-F-T-254: Dose Volume Histogram (DVH) Analysis of Breath Hold Vs Free Breathing Techniques for Esophageal Tumors

    International Nuclear Information System (INIS)

    Badkul, R; Doke, K; Pokhrel, D; Aguilera, N; Lominska, C

    2016-01-01

    Purpose: Lung and heart doses and associated toxicity are of concern in radiotherapy for esophageal cancer. This study evaluates the dosimetry of deep-inspiration-breath-hold (DIBH) technique as compared to freebreathing( FB) using 3D-conformal treatment(3D-CRT) of esophageal cancer. Methods: Eight patients were planned with FB and DIBH CT scans. DIBH scans were acquired using Varian RPM system. FB and DIBH CTs were contoured per RTOG-1010 to create the planning target volume(PTV) as well as organs at risk volumes(OAR). Two sets of gross target volumes(GTV) with 5cm length were contoured for each patient: proximal at the level of the carina and distal at the level of gastroesophageal junction and were enlarged with appropriate margin to generate Clinical Target Volume and PTV. 3D-CRT plans were created on Eclipse planning system for 45Gy to cover 95% of PTV in 25 fractions for both proximal and distal tumors on FB and DIBH scans. For distal tumors celiac nodes were covered electively. DVH parameters for lung and heart OARs were generated and analyzed. Results: All DIBH DVH parameters were normalized to FB plan values. Average of heart-mean and heart-V40 was 0.70 and 0.66 for proximal lesions. For distal lesions ratios were 1.21 and 2.22 respectively. For DIBH total lung volume increased by 2.43 times versus FB scan. Average of lung-mean, V30, V20, V10, V5 are 0.82, 0.92, 0.76, 0.77 and 0.79 for proximal lesions and 1.17,0.66,0.87,0.93 and 1.03 for distal lesions. Heart doses were lower for breath-hold proximal lesions but higher for distal lesions as compared to free-breathing plans. Lung doses were lower for both proximal and distal breath-hold lesions except mean lung dose and V5 for distal lesions. Conclusion: This study showed improvement of OAR doses for esophageal lesions at mid-thoracic level utilizing DIBH vs FB technique but did not show consistent OAR sparing with DIBH for distal lesions.

  5. Loading dose of vancomycin in critically ill patients: 15 mg/kg is a better choice than 500 mg.

    Science.gov (United States)

    Mohammedi, I; Descloux, E; Argaud, L; Le Scanff, J; Robert, D

    2006-03-01

    Delays in antimicrobial therapy in high-risk patients with infection may have deleterious effects on clinical outcomes. Therefore, appropriate treatment must be initiated promptly. The objective of this prospective study was to determine the better loading dose of vancomycin in critically ill patients with suspected Gram-positive infections. Two groups of patients were studied successively: Group A, loading dose of 500 mg; and Group B, loading dose of 15 mg/kg. The mean post-loading dose serum vancomycin concentration was significantly higher in Group B than in Group A (19.1 +/- 7.4 mg/L versus 10.4 +/- 2.7 mg/L; P < 0.001), without producing toxic peak levels. Clinical cure rates were significantly different for infected patients in Group B compared with Group A: 93% (14 of 15 patients) versus 56% (10 of 18 patients), respectively. However, the proportion of patients surviving to Intensive Care Unit discharge was similar. Because vancomycin is believed to achieve maximum killing at concentrations in serum of four to five times the minimum inhibitory concentration for the infecting organism, our results suggest that the 15 mg/kg loading dose should be preferred.

  6. Emotional intelligence moderates the relationship between regional gray matter volume in the bilateral temporal pole and critical thinking disposition.

    Science.gov (United States)

    Yao, Xiaonan; Yuan, Shuge; Yang, Wenjing; Chen, Qunlin; Wei, Dongtao; Hou, Yuling; Zhang, Lijie; Qiu, Jiang; Yang, Dong

    2018-04-01

    Critical thinking enables people to form sound beliefs and provides a basis for emotional life. Research has indicated that individuals with better critical thinking disposition can better recognize and regulate their emotions, though the neuroanatomical mechanisms involved in this process remain to be elucidated. Further, the influence of emotional intelligence on the relationship between brain structure and critical thinking disposition has not been examined. The present study utilized voxel-based morphometry (VBM) to investigate the neural structures underlying critical thinking disposition in a large sample of college students (N = 296). Regional gray matter volume (rGMV) in the bilateral temporal pole, which reflects an individual's ability to process social and emotional information, was negatively correlated with critical thinking disposition. In addition, rGMV in bilateral para hippocampal regions -regions involved in contextual association/emotional regulation-exhibited negative correlation with critical thinking disposition. Further analysis revealed that emotional intelligence moderated the relationship between rGMV of the temporal pole and critical thinking disposition. Specifically, critical thinking disposition was associated with decreased GMV of the temporal pole for individuals who have relatively higher emotional intelligence rather than lower emotional intelligence. The results of the present study indicate that people who have higher emotional intelligence exhibit more effective and automatic processing of emotional information and tend to be strong critical thinkers.

  7. Risk evaluation of the Arctic environmental POP exposure based on critical body residue and critical daily dose using captive Greenland sledge dogs (Canis familiaris) as surrogate species.

    Science.gov (United States)

    Sonne, Christian; Gustavson, Kim; Eulaers, Igor; Desforges, Jean-Pierre; Letcher, Robert J; Rigét, Frank F; Styrishave, Bjarne; Dietz, Rune

    2016-03-01

    The risk from POP (persistent organic pollutant) exposure and subsequent reproductive, immunotoxic and liver histopathological effects was evaluated in a classical parallel trial on Greenland sledge dogs (Canis familiaris) fed contaminated minke whale (Balaenoptera acutorostrata) blubber. First the critical body residues (CBRs) were estimated using the physiologically-based pharmacokinetic (PBPK) model for seven POP compounds based on rat critical daily doses (CDDs). These were then compared with the actual daily oral POP doses (DD) and body residues (BR) in the sledge dogs by calculating risk quotients (RQDD: DD/CDD; RQBR: BR/CBR; ≥1 indicates risk). The results showed that risk quotients for reproductive, immunotoxic and liver histopathological effects were significantly lowest in the control group (preproductive and immunotoxic effects while those for liver histopathological effects ranged from 0.7-3.0. PCBs (polychlorinated biphenyls) and chlordanes were the dominant driver behind high immune and reproductive RQs while dieldrin was the most important factor behind RQs for liver histopathology. Principal component analyses and Spearman rank correlation analyses showed that complement and cellular immune parameters were significantly negative correlated with RQBR (all pdogs. It is also clear that RQBR is the best reflector of health effects from POP exposure and that it is especially accurate in predicting immune and reproductive effects. We recommend that PBPK modelled (CBR) and RQBR should be used in the assessment of POP exposure and health effects in Arctic top predators. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Dose-volume histogram and dose-surface histogram analysis for skin reactions to carbon ion radiotherapy for bone and soft tissue sarcoma.

    Science.gov (United States)

    Yanagi, Takeshi; Kamada, Tadashi; Tsuji, Hiroshi; Imai, Reiko; Serizawa, Itsuko; Tsujii, Hirohiko

    2010-04-01

    To evaluate the usefulness of the dose-volume histogram (DVH) and dose-surface histogram (DSH) as clinically relevant and available parameters that helped to identify bone and soft tissue sarcoma patients at risk of developing late skin reactions, including ulceration, when treated with carbon ion radiotherapy. Thirty-five patients with bone and soft tissue sarcoma treated with carbon ion beams were studied. The clinical skin reactions were evaluated. Some pretreatment variables were compared with the grade of late skin reactions. Average DVH and DSH were established in accordance with the grading of the skin reactions. Prescribed dose, the difference in depths between the skin surface and the proximal extent of the tumor, and some DVH/DSH parameters were correlated with late skin reaction (> or = grade 3) according to univariate analysis. Furthermore, the area irradiated with over 60 GyE (S(60)>20 cm(2)) on DSH was the most important factor by multivariate analysis. The area irradiated with over 60 GyE (S(60)>20 cm(2)) on DSH was found to be a parameter for use as a predictor of late skin reactions. Copyright 2009 Elsevier Ireland Ltd. All rights reserved.

  9. Dose commitments due to radioactive releases from nuclear power plant sites in 1991. Volume 13

    International Nuclear Information System (INIS)

    Baker, D.A.

    1995-04-01

    Population and individual radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1991. Fifty-year dose commitments for a one-year exposure from both liquid and atmospheric releases were calculated for four population groups (infant, child, teenager and adult) residing between 2 and 80 km from each of 72 reactor sites. This report tabulates the results of these calculations, showing the dose commitments for both water and airborne pathways for each age group and organ. Also included for each of the sites is an estimate of individual doses which are compared with 10 CFR Part 50, Appendix 1 design objectives. The total collective dose commitments (from both liquid and airborne pathways) for each site ranged from a high of 22 person-rem to a low of 0.002 person-rem for the sites with plants in operation and producing power during the year. The arithmetic mean was 1.2 person-rem. The total population dose for all sites was estimated at 88 person-rem for the 130 million people considered at risk. The individual dose commitments estimated for all sites were below the Appendix 1 design objectives

  10. Dose commitments due to radioactive releases from nuclear power plant sites in 1990: Volume 12

    International Nuclear Information System (INIS)

    Baker, D.A.

    1994-11-01

    Population and individual radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1990. Fifty-year dose commitments for a one-year exposure from both liquid and atmospheric releases were calculated for four population groups (infant, child, teen-ager and adult) residing between 2 and 80 km from each of 72 reactor sites. This report tabulates the results of these calculations, showing the dose commitments for both water and airborne pathways for each age group and organ. Also included for each of the sites is an estimate of individual doses which are compared with 10 CFR Part 50, Appendix 1 design objectives. The total collective dose commitments (from both liquid and airborne pathways) for each site ranged from a high of 15 person-rem to a low of 0.002 person-rem for the sites with plants in operation and producing power during the year. The arithmetic mean was 1.1 person-rem. The total population dose for all sites was estimated at 78 person-rem for the 130 million people considered at risk. The individual dose commitments estimated for all sites were below the Appendix 1 design objectives

  11. Dose commitments due to radioactive releases from nuclear power plant sites in 1992. Volume 14

    International Nuclear Information System (INIS)

    Aaberg, R.L.; Baker, D.A.

    1996-03-01

    Population and individual radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1992. Fifty-year dose commitments for a 1-year exposure from both liquid and atmospheric releases were calculated for four population groups (infant, child, teenager, and adult) residing between 2 and 80 km from each of 72 reactor sites. This report tabulates the results of these calculations, showing the dose commitments for both water and airborne pathways for each age group and organ. Also included for each of the sites is an estimate of individual doses, which are compared with 10 CFR Part 50, Appendix I, design objectives. The total collective dose commitments (from both liquid and airborne pathways) for each site ranged from a high of 3.7 person-rem to a low of 0.0015 person-rem for the sites with plants in operation and producing power during the year. The arithmetic mean was 0.66 person-rem. The total population dose for all sites was estimated at 47 person-rem for the 130-million people considered at risk. The individual dose commitments estimated for all sites were below the 10 CFR 50, Appendix I, design objectives

  12. Dose commitments due to radioactive releases from nuclear power plant sites in 1991. Volume 13

    Energy Technology Data Exchange (ETDEWEB)

    Baker, D.A. [Pacific Northwest Lab., Richland, WA (United States)

    1995-04-01

    Population and individual radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1991. Fifty-year dose commitments for a one-year exposure from both liquid and atmospheric releases were calculated for four population groups (infant, child, teenager and adult) residing between 2 and 80 km from each of 72 reactor sites. This report tabulates the results of these calculations, showing the dose commitments for both water and airborne pathways for each age group and organ. Also included for each of the sites is an estimate of individual doses which are compared with 10 CFR Part 50, Appendix 1 design objectives. The total collective dose commitments (from both liquid and airborne pathways) for each site ranged from a high of 22 person-rem to a low of 0.002 person-rem for the sites with plants in operation and producing power during the year. The arithmetic mean was 1.2 person-rem. The total population dose for all sites was estimated at 88 person-rem for the 130 million people considered at risk. The individual dose commitments estimated for all sites were below the Appendix 1 design objectives.

  13. Dose commitments due to radioactive releases from nuclear power plant sites in 1992. Volume 14

    Energy Technology Data Exchange (ETDEWEB)

    Aaberg, R.L.; Baker, D.A.

    1996-03-01

    Population and individual radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1992. Fifty-year dose commitments for a 1-year exposure from both liquid and atmospheric releases were calculated for four population groups (infant, child, teenager, and adult) residing between 2 and 80 km from each of 72 reactor sites. This report tabulates the results of these calculations, showing the dose commitments for both water and airborne pathways for each age group and organ. Also included for each of the sites is an estimate of individual doses, which are compared with 10 CFR Part 50, Appendix I, design objectives. The total collective dose commitments (from both liquid and airborne pathways) for each site ranged from a high of 3.7 person-rem to a low of 0.0015 person-rem for the sites with plants in operation and producing power during the year. The arithmetic mean was 0.66 person-rem. The total population dose for all sites was estimated at 47 person-rem for the 130-million people considered at risk. The individual dose commitments estimated for all sites were below the 10 CFR 50, Appendix I, design objectives.

  14. Occupational dose reduction at Department of Energy contractor facilities: Bibliography of selected readings in radiation protection and ALARA; Volume 5

    Energy Technology Data Exchange (ETDEWEB)

    Dionne, B.J.; Sullivan, S.G.; Baum, J.W. [Brookhaven National Lab., Upton, NY (United States)

    1994-01-01

    Promoting the exchange of information related to implementation of the As Low as Reasonably Achievable (ALARA) philosophy is a continuing objective for the Department of Energy (DOE). This report was prepared by the Brookhaven National Laboratory (BNL) ALARA Center for the DOE Office of Health. It contains the fifth in a series of bibliographies on dose reduction at DOE facilities. The BNL ALARA Center was originally established in 1983 under the sponsorship of the Nuclear Regulatory Commission to monitor dose-reduction research and ALARA activities at nuclear power plants. This effort was expanded in 1988 by the DOE`s Office of Environment, Safety and Health, to include DOE nuclear facilities. This bibliography contains abstracts relating to various aspects of ALARA program implementation and dose-reduction activities, with a specific focus on DOE facilities. Abstracts included in this bibliography were selected from proceedings of technical meetings, journals, research reports, searches of the DOE Energy, Science and Technology Database (in general, the citation and abstract information is presented as obtained from this database), and reprints of published articles provided by the authors. Facility types and activities covered in the scope of this report include: radioactive waste, uranium enrichment, fuel fabrication, spent fuel storage and reprocessing, facility decommissioning, hot laboratories, tritium production, research, test and production reactors, weapons fabrication and testing, fusion, uranium and plutonium processing, radiography, and accelerators. Information on improved shielding design, decontamination, containments, robotics, source prevention and control, job planning, improved operational and design techniques, as well as on other topics, has been included. In addition, DOE/EH reports not included in previous volumes of the bibliography are in this volume (abstracts 611 to 684). This volume (Volume 5 of the series) contains 217 abstracts.

  15. Occupational dose reduction at Department of Energy contractor facilities: Bibliography of selected readings in radiation protection and ALARA; Volume 5

    International Nuclear Information System (INIS)

    Dionne, B.J.; Sullivan, S.G.; Baum, J.W.

    1994-01-01

    Promoting the exchange of information related to implementation of the As Low as Reasonably Achievable (ALARA) philosophy is a continuing objective for the Department of Energy (DOE). This report was prepared by the Brookhaven National Laboratory (BNL) ALARA Center for the DOE Office of Health. It contains the fifth in a series of bibliographies on dose reduction at DOE facilities. The BNL ALARA Center was originally established in 1983 under the sponsorship of the Nuclear Regulatory Commission to monitor dose-reduction research and ALARA activities at nuclear power plants. This effort was expanded in 1988 by the DOE's Office of Environment, Safety and Health, to include DOE nuclear facilities. This bibliography contains abstracts relating to various aspects of ALARA program implementation and dose-reduction activities, with a specific focus on DOE facilities. Abstracts included in this bibliography were selected from proceedings of technical meetings, journals, research reports, searches of the DOE Energy, Science and Technology Database (in general, the citation and abstract information is presented as obtained from this database), and reprints of published articles provided by the authors. Facility types and activities covered in the scope of this report include: radioactive waste, uranium enrichment, fuel fabrication, spent fuel storage and reprocessing, facility decommissioning, hot laboratories, tritium production, research, test and production reactors, weapons fabrication and testing, fusion, uranium and plutonium processing, radiography, and accelerators. Information on improved shielding design, decontamination, containments, robotics, source prevention and control, job planning, improved operational and design techniques, as well as on other topics, has been included. In addition, DOE/EH reports not included in previous volumes of the bibliography are in this volume (abstracts 611 to 684). This volume (Volume 5 of the series) contains 217 abstracts

  16. Correlation of Acute and Late Brainstem Toxicities With Dose-Volume Data for Pediatric Patients With Posterior Fossa Malignancies

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Ronica H., E-mail: rhazari@emory.edu [Department of Radiation Oncology, Winship Cancer Institute, Emory University College of Medicine, Atlanta, Georgia (United States); Ganju, Rohit G.; Schreibmann, Edward [Department of Radiation Oncology, Winship Cancer Institute, Emory University College of Medicine, Atlanta, Georgia (United States); Chen, Zhengjia; Zhang, Chao [Department of Biostatistics and Bioinformatics Shared Resource, Winship Cancer Institute, Emory University Rollins School of Public Health, Atlanta, Georgia (United States); Jegadeesh, Naresh; Cassidy, Richard; Deng, Claudia; Eaton, Bree R.; Esiashvili, Natia [Department of Radiation Oncology, Winship Cancer Institute, Emory University College of Medicine, Atlanta, Georgia (United States)

    2017-06-01

    Purpose: Radiation-induced brainstem toxicity after treatment of pediatric posterior fossa malignancies is incompletely understood, especially in the era of intensity modulated radiation therapy (IMRT). The rates of, and predictive factors for, brainstem toxicity after photon RT for posterior fossa tumors were examined. Methods and Materials: After institutional review board approval, 60 pediatric patients treated at our institution for nonmetastatic infratentorial ependymoma and medulloblastoma with IMRT were included in the present analysis. Dosimetric variables, including the mean and maximum dose to the brainstem, the dose to 10% to 90% of the brainstem (in 10% increments), and the volume of the brainstem receiving 40, 45, 50, and 55 Gy were recorded for each patient. Acute (onset within 3 months) and late (>3 months of RT completion) RT-induced brainstem toxicities with clinical and radiographic correlates were scored using Common Terminology Criteria for Adverse Events, version 4.0. Results: Patients aged 1.4 to 21.8 years underwent IMRT or volumetric arc therapy postoperatively to the posterior fossa or tumor bed. At a median clinical follow-up period of 2.8 years, 14 patients had developed symptomatic brainstem toxicity (crude incidence 23.3%). No correlation was found between the dosimetric variables examined and brainstem toxicity. Vascular injury or ischemia showed a strong trend toward predicting brainstem toxicity (P=.054). Patients with grade 3 to 5 brainstem toxicity had undergone treatment to significant volumes of the posterior fossa. Conclusion: The results of the present series demonstrate a low, but not negligible, risk of brainstem radiation necrosis for pediatric patients with posterior fossa malignancies treated with IMRT. No specific dose-volume correlations were identified; however, modern treatment volumes might help limit the incidence of severe toxicity. Additional work investigating inherent biologic sensitivity might also provide

  17. WE-B-304-02: Treatment Planning Evaluation and Optimization Should Be Biologically and Not Dose/volume Based

    International Nuclear Information System (INIS)

    Deasy, J.

    2015-01-01

    The ultimate goal of radiotherapy treatment planning is to find a treatment that will yield a high tumor control probability (TCP) with an acceptable normal tissue complication probability (NTCP). Yet most treatment planning today is not based upon optimization of TCPs and NTCPs, but rather upon meeting physical dose and volume constraints defined by the planner. It has been suggested that treatment planning evaluation and optimization would be more effective if they were biologically and not dose/volume based, and this is the claim debated in this month’s Point/Counterpoint. After a brief overview of biologically and DVH based treatment planning by the Moderator Colin Orton, Joseph Deasy (for biological planning) and Charles Mayo (against biological planning) will begin the debate. Some of the arguments in support of biological planning include: this will result in more effective dose distributions for many patients DVH-based measures of plan quality are known to have little predictive value there is little evidence that either D95 or D98 of the PTV is a good predictor of tumor control sufficient validated outcome prediction models are now becoming available and should be used to drive planning and optimization Some of the arguments against biological planning include: several decades of experience with DVH-based planning should not be discarded we do not know enough about the reliability and errors associated with biological models the radiotherapy community in general has little direct experience with side by side comparisons of DVH vs biological metrics and outcomes it is unlikely that a clinician would accept extremely cold regions in a CTV or hot regions in a PTV, despite having acceptable TCP values Learning Objectives: To understand dose/volume based treatment planning and its potential limitations To understand biological metrics such as EUD, TCP, and NTCP To understand biologically based treatment planning and its potential limitations

  18. Patient-reported intestinal toxicity from whole pelvis intensity-modulated radiotherapy: First quantification of bowel dose-volume effects.

    Science.gov (United States)

    Sini, Carla; Noris Chiorda, Barbara; Gabriele, Pietro; Sanguineti, Giuseppe; Morlino, Sara; Badenchini, Fabio; Cante, Domenico; Carillo, Viviana; Gaetano, Marcella; Giandini, Tommaso; Landoni, Valeria; Maggio, Angelo; Perna, Lucia; Petrucci, Edoardo; Sacco, Vincenzo; Valdagni, Riccardo; Rancati, Tiziana; Fiorino, Claudio; Cozzarini, Cesare

    2017-08-01

    Intestinal toxicity is commonly experienced during whole-pelvis intensity-modulated radiotherapy (WPRT) for prostate cancer. The aim of the current study was to assess bowel dose-volume relationships for acute patient-reported intestinal symptoms of patients treated with WPRT for prostate cancer. Complete data of 206 patients were available; the median dose to pelvic nodes was 51.8Gy (range 50.4-54.4, 1.7-2Gy/fr). Intestinal symptoms were assessed as changes in the Inflammatory Bowel Disease Questionnaire scores relative to the Bowel Domain (IBDQ-B) between baseline and radiotherapy mid-point/end. The 25th percentiles of the most severe worsening from baseline (ΔIBDQ-B) were set as end-points. The impact of bowel loops and sigmoid colon dose-volume/surface parameters as well as selected clinical parameters were investigated using multivariate logistic regression. Analyses were focused on the four questions showing a median ΔIBDQ-B>0. No dose volume/surface parameters were predictive, other than ΔIBDQ5≥3 (loose stools): when grouping patients according to bowel DVHs (high risk: V20>470cc, V30>245cc, V42>110cc; low risk: all the remaining patients), a two-variable model including high-risk DVH-shape (OR: 9.3) and age (protective, OR: 0.94) was assessed. The model showed good calibration (slope: 1.003, R 2 =0.92) and was found to be robust after bootstrap-based internal validation. Constraining the bowel loops may reduce the risk of loose stools. The risk is higher for younger patients. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. A new approach for the calculation of critical organ dose in nuclear medicine applications

    International Nuclear Information System (INIS)

    Yasar, Dogan; Tugrul, A. Beril

    2005-01-01

    The geometrical factor that is calculated to keep in mind the radiation source and detector position is rather frequently used in radiation measuring and calculating methods. In this study, using the geometrical factor is intended to suggest a new model to measure the absorbed dose in nuclear medicine applications. Therefore, the source and target organ's geometries are accepted to be disc and parallel to each other. In this manner, a mathematical model for the geometry of these discs is proposed and a disc-disc geometry factor is calculated. Theoretical calculations have been carried out with the MIRD (medical internal absorbed dose) method, which is widely used to the absorbed dose calculations in nuclear medicine. Absorbed radiation dose is separately calculated for a target organ, which is the testis, with disc-disc geometry factor model and MIRD model. Both the results are compared and the results of disc-disc geometry factor model are shown to be harmonious and acceptable with the results of MIRD model

  20. Critical appraisal of a fixed combination of esomeprazole and low dose aspirin in risk reduction

    Directory of Open Access Journals (Sweden)

    Ravi Vachhani

    2010-06-01

    Full Text Available Ravi Vachhani1, Doumit Bouhaidar1, Alvin Zfass1, Bimaljit Sandhu1, Ali Nawras21Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University Medical Center, Richmond, Virginia 23298–0341, USA; 2Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, The University of Toledo Medical Center, Toledo, Ohio 43606-3390, USAAbstract: Low dose aspirin (≤325 mg is routinely used for primary and secondary prophylaxis of cardiovascular and cerebrovascular events. The use of low dose aspirin is associated with two-to four-fold greater risk of symptomatic or complicated peptic ulcers. Risk factors associated with low dose aspirin induced gastrointestinal toxicity includes prior history of ulcer or upper gastrointestinal (GI bleeding, concomitant use of other nonsteroidal anti-inflammatory drugs, corticosteroid or warfarin, dual antiplatelet therapy, Helicobacter pylori (H. pylori infection, and advanced age. Esomeprazole, like other proton pump inhibitors (PPIs is very effective in decreasing the risk of aspirin induced gastrointestinal toxicity. Although evidence to support esomeprazole or other PPIs for primary prophylaxis in aspirin induced gastrointestinal toxicity is limited, its role in secondary prophylaxis is well established.Keywords: esomeprazole, proton pump inhibitors, low dose aspirin, gastrointestinal toxicity, gastrointestinal bleeding

  1. Comparison with dose-volume histograms of two conformal irradiation techniques used for the treatment of T2N0M0 nasopharyngeal cancer, one with association of photons and protons and another with photons alone; Comparaison par les histogrammes dose-volume de deux techniques d'irradiation conformationnelle des cancers du nasopharynx classes T4N0M0, l'une par photons et protons et l'autre par photons seuls

    Energy Technology Data Exchange (ETDEWEB)

    Noel, G.; Ferrand, R.; Desblancs, C.L.; Mazeron, J.J. [Centre de protontherapie, 91 - Orsay (France); Boisserie, G.; Dessard-Diana, B.; Gasowski, M.; Simon, J.M.; Baillet, F.; Mazeron, J.J. [Groupe Hospitalier la Pitie-Salpetriere, Service des Tumeurs, 75 - Paris (France); Hasboun, D. [Groupe Hospitalier la Pitie-Salpetriere, Service de Radiologie, 75 - Paris (France)

    2002-12-01

    treatment with combined photons and protons than with photons alone. The average GTV encompassed y the 70 Gy/CGE isodose was larger by 65% with the association compared to photons alone. The conformation ratio (tissue volume encompassed by the 95% isodose/GTV encompassed by the 95% isodose) was 3.1 with the association compared to 5.7 with photons alone. For the CTV2, there were no differences in different criteria according to the both irradiation techniques. For the critical, radiosensitive organs, the comparison of the majority of the criteria was in favour of the association of protons and photons. Overall, 78% of the criteria were in favour of the association. For locally advanced nasopharyngeal cancer without clinical adenopathy, irradiation by photons and protons increases the tumor volume irradiated at the prescribed dose and decreases the volume or critical organs irradiated and the total dose delivered within them. (author)

  2. Dose-Volume Histogram Parameters and Clinical Factors Associated With Pleural Effusion After Chemoradiotherapy in Esophageal Cancer Patients

    International Nuclear Information System (INIS)

    Shirai, Katsuyuki; Tamaki, Yoshio; Kitamoto, Yoshizumi; Murata, Kazutoshi; Satoh, Yumi; Higuchi, Keiko; Nonaka, Tetsuo; Ishikawa, Hitoshi; Katoh, Hiroyuki; Takahashi, Takeo; Nakano, Takashi

    2011-01-01

    Purpose: To investigate the dose-volume histogram parameters and clinical factors as predictors of pleural effusion in esophageal cancer patients treated with concurrent chemoradiotherapy (CRT). Methods and Materials: Forty-three esophageal cancer patients treated with definitive CRT from January 2001 to March 2007 were reviewed retrospectively on the basis of the following criteria: pathologically confirmed esophageal cancer, available computed tomography scan for treatment planning, 6-month follow-up after CRT, and radiation dose ≥50 Gy. Exclusion criteria were lung metastasis, malignant pleural effusion, and surgery. Mean heart dose, mean total lung dose, and percentages of heart or total lung volume receiving ≥10-60 Gy (Heart-V 10 to V 60 and Lung-V 10 to V 60 , respectively) were analyzed in relation to pleural effusion. Results: The median follow-up time was 26.9 months (range, 6.7-70.2) after CRT. Of the 43 patients, 15 (35%) developed pleural effusion. By univariate analysis, mean heart dose, Heart-V 10 to V 60 , and Lung-V 50 to V 60 were significantly associated with pleural effusion. Poor performance status, primary tumor of the distal esophagus, and age ≥65 years were significantly related with pleural effusion. Multivariate analysis identified Heart-V 50 as the strongest predictive factor for pleural effusion (p = 0.01). Patients with Heart-V 50 50 50 ≥40% had 6%, 44%, and 64% of pleural effusion, respectively (p 50 is a useful parameter for assessing the risk of pleural effusion and should be reduced to avoid pleural effusion.

  3. The use of low-volume dosing in the eye irritation test.

    Science.gov (United States)

    Lambert, L A; Chambers, W A; Green, S; Gupta, K C; Hill, R N; Hurley, P M; Lee, C C; Lee, J K; Liu, P T; Lowther, D K

    1993-02-01

    The Draize rabbit eye test was developed to provide a method for assessing the irritation potential of materials that might come in contact with human eyes. The method involves the instillation of 0.1 ml of a test liquid (100 mg solid) into the conjunctival sac of an animal's eye. A refinement of the Draize test is the low-volume eye test in which 0.01 ml of a substance is placed directly on the cornea of the eye. Studies indicate that the low-volume method provides a better correlation to human eye irritation experience for some substances. The Interagency Regulatory Alternatives Group (IRAG) proposes that the low-volume eye test can be used to substantiate the irritancy of suspect severe ocular irritants that have not been eliminated by various pre-eye test 'screens'. A substance testing positive by the low-volume method can be classified as an irritant; one that tests negative will require further testing by the use of the 0.1-ml volume procedure. For all other definitive testing, the Draize test (0.1 ml) should be used. Results from a questionnaire distributed at the IRAG workshop showed that many workshop participants thought that the low-volume test should be used as an eye irritation screening procedure.

  4. Population dose commitments due to radioactive releases from nuclear power plant sites in 1981. Volume 3

    International Nuclear Information System (INIS)

    Baker, D.A.; Peloquin, R.A.

    1985-01-01

    Population radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1981. Fifty-year dose commitments from a one-year exposure were calculated from both liquid and atmospheric releases for four population groups (infant, child, teenager and adult) residing between 2 and 80 km from each site. This report tabulates the results of these calculations, showing the dose commitments for both liquid and airborne pathways for each age group and organ. Also included for each site is a histogram showing the fraction of the total population within 2 to 80 km around each site receiving various average dose commitments from the airborne pathways. The total dose commitment from both liquid and airborne pathways from 48 sites ranged from a high of 20 person-rem to a low of 0.008 person-rem with an arithmetic mean of 3 person-rem. The total population dose for all sites was estimated at 160 person-rem for the 98 million people considered at risk

  5. Initial dosing regimen of vancomycin to achieve early therapeutic plasma concentration in critically ill patients with MRSA infection based on APACHE II score.

    Science.gov (United States)

    Imaura, Masaharu; Yokoyama, Haruko; Kohata, Yuji; Kanai, Riichiro; Kohyama, Tomoki; Idemitsu, Wataru; Maki, Yuichi; Igarashi, Takashi; Takahashi, Hiroyuki; Kanno, Hiroshi; Yamada, Yasuhiko

    2016-06-01

    It is essential to assure the efficacy of antimicrobials at the initial phase of therapy. However, increasing the volume of distribution (Vd) of hydrophilic antimicrobials in critically ill patients leads to reduced antimicrobial concentration in plasma and tissue, which may adversely affect the efficacy of that therapy. The aim of the present study was to establish a theoretical methodology for setting an appropriate level for initial vancomycin therapy in individual patients based on Acute Physiology and Chronic Health Evaluation (APACHE) II score. We obtained data from patients who received intravenous vancomycin for a suspected or definitively diagnosed Gram-positive bacterial infection within 72 h after admission to the intensive care unit. The Vd and elimination half-life (t 1/2) of vancomycin values were calculated using the Bayesian method, and we investigated the relationship between them and APACHE II score. There were significant correlations between APACHE II scores and Vd/actual body weight (ABW), as well as t 1/2 (r = 0.58, p vancomycin could be estimated using the following regression equations using APACHE II score.[Formula: see text] [Formula: see text]We found that APACHE II score was a useful index for predicting the Vd and t 1/2 of vancomycin, and used that to establish an initial vancomycin dosing regimen comprised of initial dose and administration interval for individual patients.

  6. Dose-volume histogram parameters of high-dose-rate brachytherapy for Stage I-II cervical cancer (≤4cm) arising from a small-sized uterus treated with a point A dose-reduced plan.

    Science.gov (United States)

    Nakagawa, Akiko; Ohno, Tatsuya; Noda, Shin-ei; Kubo, Nobuteru; Kuwako, Keiko; Saitoh, Jun-Ichi; Nakano, Takashi

    2014-07-01

    We investigated the rectal dose-sparing effect and tumor control of a point A dose-reduced plan in patients with Stage I-II cervical cancer (≤4 cm) arising from a small-sized uterus. Between October 2008 and August 2011, 19 patients with Stage I-II cervical cancer (≤4 cm) were treated with external beam radiotherapy (EBRT) for the pelvis and CT-guided brachytherapy. Seven patients were treated with brachytherapy with standard loading of source-dwell positions and a fraction dose of 6 Gy at point A (conventional brachy-plan). The other 12 patients with a small uterus close to the rectum or small intestine were treated with brachytherapy with a point A dose-reduction to match D2cc of the rectum and <6 Gy as the dose constraint ('point A dose-reduced plan') instead of the 6-Gy plan at point A ('tentative 6-Gy plan'). The total doses from EBRT and brachytherapy were added up and normalized to a biological equivalent dose of 2 Gy per fraction (EQD2). The median doses to the high-risk clinical target volume (HR-CTV) D90 in the conventional brachy-plan, tentative 6-Gy plan and point A dose-reduced plan were 62 GyEQD2, 80 GyEQD2 and 64 GyEQD2, respectively. The median doses of rectal D2cc in the corresponding three plans were 42 GyEQD2, 62 GyEQD2 and 51 GyEQD2, respectively. With a median follow-up period of 35 months, three patients developed Grade-1 late rectal complications and no patients developed local recurrence. Our preliminary results suggested that CT-guided brachytherapy using an individualized point A dose-reduced plan might be useful for reducing late rectal complications while maintaining primary tumor control. © The Author 2014. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  7. Late swallowing dysfunction and dysphagia after radiotherapy for pharynx cancer: Frequency, intensity and correlation with dose and volume parameters

    International Nuclear Information System (INIS)

    Jensen, Kenneth; Lambertsen, Karin; Grau, Cai

    2007-01-01

    Background and purpose: Dysphagia and swallowing problems are common in pharynx cancer patients treated with radiotherapy. Dysfunction of the upper aerodigestive tract may lead to reduced quality of life, malnutrition and aspiration pneumonia. The aim of the current study was to describe swallowing function after radiotherapy and examine its correlation with irradiated volume and dose. Patients and methods: All recurrence free patients treated for pharynx cancer with radical radiotherapy at our institution, between 1998 and 2002, were invited to participate, 35 (55% of eligible) agreed. Patients were examined with EORTC quality of life questionnaires and functional endoscopic evaluation of swallowing. Organs at risk were delineated on planning CT scans, available for 25 patients. Results: Eighty-three percent of patients had some degree of dysphagia. Reduced sensitivity was observed in 94%, residues in 88%, penetration in 59% and aspiration in 18% of patients. Several significant correlations were found between both subjective and objective swallowing problems and DVH parameters of the upper aerodigestive tract. Doses less than 60 Gy to the supraglottic region, the larynx and upper esophageal sphincter resulted in a low risk of aspiration. Discussion: Both subjective and objective swallowing problems were frequent and severe after radiotherapy for pharynx cancer. Swallowing dysfunction was correlated with dose and volume parameters of the upper aerodigestive tract

  8. Dose-volume analysis for respiratory toxicity in intrathoracic esophageal cancer patients treated with definitive chemoradiotherapy using extended fields.

    Science.gov (United States)

    Tanabe, Satoshi; Myojin, Miyako; Shimizu, Shinichi; Fujino, Masaharu; Takahashi, Hiroaki; Shirato, Hiroki; Ito, Yoichi M; Ishikawa, Masayori; Hosokawa, Masao

    2013-11-01

    We evaluated the relationship between dosimetric parameters (DPs) and the incidence of radiation pneumonitis (RP) and investigated the feasibility of a proposed treatment planning technique with the potential of reducing RP in esophageal cancer patients treated with definitive chemoradiotherapy using extended fields. A total of 149 patients with locally advanced esophageal cancer were prospectively enrolled for extended-field radiotherapy (EFRT) to three-field regional lymphatics between September 2004 and June 2009. We retrospectively reviewed 86 consecutive patients who were treated with a total dose of 50.4 Gy (plus an optional 9 Gy boost) and were available for dose-volume analysis. Lung DPs of patients in the Grade 0-1 RP (RPG≤1) group and the Grade 2-5 RP (RPG≥2) group were compared. We compared the proposed plan with the conventional plan to 50.4 Gy on DPs for each case. Of these 86 patients, 10 (12%) developed RPG≥2 (Grade 2, n = 2 patients; Grade 3, n = 3; Grade 4, n = 3; Grade 5, n = 2). The patients in the RPG≤1 group showed significantly lower (P RPG≥2 group. There were two advantages gained from the proposed plan for V5 (<55%) and V10 (< 37%) values and the conformity of the PTV. The increase in the volume of the lung exposed to low doses of EFRT was found to be associated with the incidence of RP. Our proposed plan is likely to reduce the incidence of RP.

  9. A comparative study of varying doses of enoxaparin for thromboprophylaxis in critically ill patients

    DEFF Research Database (Denmark)

    Robinson, Sian; Zincuk, Aleksander; Larsen, Ulla Lei

    2013-01-01

    critically ill patients weighing 50 - 90 kilograms were randomised in a double-blinded study to receive subcutaneous (sc) enoxaparin: 40 mg once daily (QD), 30 mg twice daily (BID), 40mg BID, or 1mg/kg QD, each administered for three days. Anti-Xa activity was measured at baseline, and daily at 4, 12, 16...

  10. Dose-volume analysis of radiation-induced trismus in head and neck cancer patients.

    Science.gov (United States)

    Gebre-Medhin, Maria; Haghanegi, Mahnaz; Robért, Lotta; Kjellén, Elisabeth; Nilsson, Per

    2016-11-01

    Trismus is a treatment-related late side effect in patients treated for cancer in the head and neck region (HNC). The condition can have a considerable negative impact on nutrition, dental hygiene, ability to speak and quality of life. We have previously studied trismus within the frame of a randomized phase 3 study of HNC patients treated with mainly three-dimensional (3D) conformal radiotherapy (CRT) and found a strong association to mean radiation dose to the mastication muscles, especially the ipsilateral masseter muscle (iMAS). In the present study we have investigated trismus prevalence and risk factors in a more recent cohort of patients, treated with todays' more updated radiation techniques. Maximal interincisal distance (MID) was measured on 139 consecutive patients. Trismus was defined as MID ≤35 mm. Patient-, disease- and treatment-specific data were retrospectively recorded. Differences between groups were analyzed and mean absorbed dose to mastication structures was evaluated. Dosimetric comparisons were made between this study and our previous results. The prevalence of trismus was 24% at a median of 16 months after completion of radiotherapy. In bivariate analysis treatment technique (3DCRT vs. intensity modulated radiotherapy or helical tomotherapy), tumor site (oropharynx vs. other sites) and mean radiation doses to the ipsilateral lateral pterygoid muscle, the paired masseter muscles and the iMAS were significantly associated with MID ≤35 mm. In multivariable analysis only mean radiation dose to the iMAS was significantly associated to MID ≤35 mm. Mean radiation dose to the ipsilateral masseter muscle is an important risk factor for trismus development. Dose reduction to this structure during radiotherapy should have a potential to diminish the prevalence of trismus in this patient group.

  11. Late swallowing dysfunction and dysphagia after radiotherapy for pharynx cancer: frequency, intensity and correlation with dose and volume parameters

    DEFF Research Database (Denmark)

    Jensen, Kenneth; Lambertsen, Karin; Grau, Cai

    2007-01-01

    function after radiotherapy and examine its correlation with irradiated volume and dose. PATIENTS AND METHODS: All recurrence free patients treated for pharynx cancer with radical radiotherapy at our institution, between 1998 and 2002, were invited to participate, 35 (55% of eligible) agreed. Patients were......BACKGROUND AND PURPOSE: Dysphagia and swallowing problems are common in pharynx cancer patients treated with radiotherapy. Dysfunction of the upper aerodigestive tract may lead to reduced quality of life, malnutrition and aspiration pneumonia. The aim of the current study was to describe swallowing...

  12. Critical Void Volume Fraction fc at Void Coalescence for S235JR Steel at Low Initial Stress Triaxiality

    Science.gov (United States)

    Grzegorz Kossakowski, Paweł; Wciślik, Wiktor

    2017-10-01

    The paper is concerned with the nucleation, growth and coalescence of microdefects in the form of voids in S235JR steel. The material is known to be one of the basic steel grades commonly used in the construction industry. The theory and methods of damage mechanics were applied to determine and describe the failure mechanisms that occur when the material undergoes deformation. Until now, engineers have generally employed the Gurson-Tvergaard- Needleman model. This material model based on damage mechanics is well suited to define and analyze failure processes taking place in the microstructure of S235JR steel. It is particularly important to determine the critical void volume fraction fc , which is one of the basic parameters of the Gurson-Tvergaard-Needleman material model. As the critical void volume fraction fc refers to the failure stage, it is determined from the data collected for the void coalescence phase. A case of multi-axial stresses is considered taking into account the effects of spatial stress state. In this study, the parameter of stress triaxiality η was used to describe the failure phenomena. Cylindrical tensile specimens with a circumferential notch were analysed to obtain low values of initial stress triaxiality (η = 0.556 of the range) in order to determine the critical void volume fraction fc . It is essential to emphasize how unique the method applied is and how different it is from the other more common methods involving parameter calibration, i.e. curve-fitting methods. The critical void volume fraction fc at void coalescence was established through digital image analysis of surfaces of S235JR steel, which involved studying real, physical results obtained directly from the material tested.

  13. Taste and Smell Disturbances after Brain Irradiation: A Dose Volume Histogram Analysis of a Prospective Observational Study

    Science.gov (United States)

    Leyrer, C. Marc; Chan, Michael D.; Peiffer, Ann M.; Horne, Elizabeth; Harmon, Michelle; Carter, Annette F.; Hinson, William H.; Mirlohi, Susan; Duncan, Susan E.; Dietrich, Andrea M.; Lesser, Glenn J.

    2014-01-01

    Purpose Radiation-induced taste and smell disturbances are prevalent in patients receiving brain radiotherapy, although the mechanisms underlying these toxicities are poorly understood. We report the results of a single institution prospective clinical trial aimed at correlating self-reported taste and smell disturbances with radiation dose delivered to defined areas within the brain and nasopharynx. Methods and Materials 22 patients with gliomas were enrolled on a prospective observational trial in which patients underwent a validated questionnaire assessing taste and smell disturbances at baseline, and at 3 and 6 weeks after commencement of brain radiotherapy. 14 patients with glioblastoma, 3 patients with grade 3 gliomas, and 5 patients with low grade gliomas participated. Median dose to tumor volume was 60 Gy (range 45–60 Gy). Dose volume histogram (DVH) analysis was performed for specific regions of interest (ROI) that were considered potential targets of radiation damage including the thalamus, temporal lobes, nasopharynx, olfactory groove, frontal pole and periventricular stem cell niche. The %v10 (percent of ROI receiving 10 Gy), %v40, and %v60 were calculated for each structure. Data from questionnaires and DVH were analyzed using stepwise regression. Results 20 of 22 patients submitted evaluable questionnaires that encompassed at least the entire radiotherapy course. 10 of 20 patients reported experiencing some degree of smell disturbance during radiotherapy, and 14 of 20 patients experienced taste disturbances. Patients reporting more severe taste toxicity also reported more severe toxicities with sense of smell (r2=0.60, p<0.006). Tumor location in the temporal lobe predicted for increased severity of taste toxicity (F3, 16=1.44, p<0.06). The nasopharynx was the only structure in which the DVH data predicted the presence of radiation-induced taste changes (r2=0.28, p<0.02). Conclusions Radiation-induced taste toxicity appears to be more common in

  14. Planning Target Volume D95 and Mean Dose Should Be Considered for Optimal Local Control for Stereotactic Ablative Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Lina [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Zhou, Shouhao [Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Balter, Peter [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Shen, Chan [Department of Health Service Research, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Gomez, Daniel R.; Welsh, James D.; Lin, Steve H. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Chang, Joe Y., E-mail: jychang@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

    2016-07-15

    Purpose: To identify the optimal dose parameters predictive for local/lobar control after stereotactic ablative radiation therapy (SABR) in early-stage non-small cell lung cancer (NSCLC). Methods and Materials: This study encompassed a total of 1092 patients (1200 lesions) with NSCLC of clinical stage T1-T2 N0M0 who were treated with SABR of 50 Gy in 4 fractions or 70 Gy in 10 fractions, depending on tumor location/size, using computed tomography-based heterogeneity corrections and a convolution superposition calculation algorithm. Patients were monitored by chest CT or positron emission tomography/CT and/or biopsy after SABR. Factors predicting local/lobar recurrence (LR) were determined by competing risk multivariate analysis. Continuous variables were divided into 2 subgroups at cutoff values identified by receiver operating characteristic curves. Results: At a median follow-up time of 31.7 months (interquartile range, 14.8-51.3 months), the 5-year time to local recurrence within the same lobe and overall survival rates were 93.8% and 44.8%, respectively. Total cumulative number of patients experiencing LR was 40 (3.7%), occurring at a median time of 14.4 months (range, 4.8-46 months). Using multivariate competing risk analysis, independent predictive factors for LR after SABR were minimum biologically effective dose (BED{sub 10}) to 95% of planning target volume (PTVD95 BED{sub 10}) ≤86 Gy (corresponding to PTV D95 physics dose of 42 Gy in 4 fractions or 55 Gy in 10 fractions) and gross tumor volume ≥8.3 cm{sup 3}. The PTVmean BED{sub 10} was highly correlated with PTVD95 BED{sub 10.} In univariate analysis, a cutoff of 130 Gy for PTVmean BED{sub 10} (corresponding to PTVmean physics dose of 55 Gy in 4 fractions or 75 Gy in 10 fractions) was also significantly associated with LR. Conclusions: In addition to gross tumor volume, higher radiation dose delivered to the PTV predicts for better local/lobar control. We recommend that both PTVD95 BED

  15. Dose sculpting with generalized equivalent uniform dose

    International Nuclear Information System (INIS)

    Wu Qiuwen; Djajaputra, David; Liu, Helen H.; Dong Lei; Mohan, Radhe; Wu, Yan

    2005-01-01

    With intensity-modulated radiotherapy (IMRT), a variety of user-defined dose distribution can be produced using inverse planning. The generalized equivalent uniform dose (gEUD) has been used in IMRT optimization as an alternative objective function to the conventional dose-volume-based criteria. The purpose of this study was to investigate the effectiveness of gEUD optimization to fine tune the dose distributions of IMRT plans. We analyzed the effect of gEUD-based optimization parameters on plan quality. The objective was to determine whether dose distribution to selected structures could be improved using gEUD optimization without adversely altering the doses delivered to other structures, as in sculpting. We hypothesized that by carefully defining gEUD parameters (EUD 0 and n) based on the current dose distributions, the optimization system could be instructed to search for alternative solutions in the neighborhood, and we could maintain the dose distributions for structures already satisfactory and improve dose for structures that need enhancement. We started with an already acceptable IMRT plan optimized with any objective function. The dose distribution was analyzed first. For structures that dose should not be changed, a higher value of n was used and EUD 0 was set slightly higher/lower than the EUD value at the current dose distribution for critical structures/targets. For structures that needed improvement in dose, a higher to medium value of n was used, and EUD 0 was set to the EUD value or slightly lower/higher for the critical structure/target at the current dose distribution. We evaluated this method in one clinical case each of head and neck, lung and prostate cancer. Dose volume histograms, isodose distributions, and relevant tolerance doses for critical structures were used for the assessment. We found that by adjusting gEUD optimization parameters, the dose distribution could be improved with only a few iterations. A larger value of n could lead to

  16. Absence of single critical dose for the amorphization of quartz under ion irradiation

    Science.gov (United States)

    Zhang, S.; Pakarinen, O. H.; Backholm, M.; Djurabekova, F.; Nordlund, K.; Keinonen, J.; Wang, T. S.

    2018-01-01

    In this work, we first simulated the amorphization of crystalline quartz under 50 keV 23 Na ion irradiation with classical molecular dynamics (MD). We then used binary collision approximation algorithms to simulate the Rutherford backscattering spectrometry in channeling conditions (RBS-C) from these irradiated MD cells, and compared the RBS-C spectra with experiments. The simulated RBS-C results show an agreement with experiments in the evolution of amorphization as a function of dose, showing what appears to be (by this measure) full amorphization at about 2.2 eVṡatom-1 . We also applied other analysis methods, such as angular structure factor, Wigner–Seitz, coordination analysis and topological analysis, to analyze the structural evolution of the irradiated MD cells. The results show that the atomic-level structure of the sample keeps evolving after the RBS signal has saturated, until the dose of about 5 eVṡatom-1 . The continued evolution of the SiO2 structure makes the definition of what is, on the atomic level, an amorphized quartz ambiguous.

  17. The effect of SDF-1α on low dose BMP-2 mediated bone regeneration by release from heparinized mineralized collagen type I matrix scaffolds in a murine critical size bone defect model.

    Science.gov (United States)

    Zwingenberger, Stefan; Langanke, Robert; Vater, Corina; Lee, Geoffrey; Niederlohmann, Eik; Sensenschmidt, Markus; Jacobi, Angela; Bernhardt, Ricardo; Muders, Michael; Rammelt, Stefan; Knaack, Sven; Gelinsky, Michael; Günther, Klaus-Peter; Goodman, Stuart B; Stiehler, Maik

    2016-09-01

    The treatment of critical size bone defects represents a challenge. The growth factor bone morphogenetic protein 2 (BMP-2) is clinically established but has potentially adverse effects when used at high doses. The aim of this study was to evaluate if stromal derived factor-1 alpha (SDF-1α) and BMP-2 released from heparinized mineralized collagen type I matrix (MCM) scaffolds have a cumulative effect on bone regeneration. MCM scaffolds were functionalized with heparin, loaded with BMP-2 and/or SDF-1α and implanted into a murine critical size femoral bone defect (control group, low dose BMP-2 group, low dose BMP-2 + SDF-1α group, and high dose BMP-2 group). After 6 weeks, both the low dose BMP-2 + SDF-1α group (5.8 ± 0.6 mm³, p = 0.0479) and the high dose BMP-2 group (6.5 ± 0.7 mm³, p = 0.008) had a significantly increased regenerated bone volume compared to the control group (4.2 ± 0.5 mm³). There was a higher healing score in the low dose BMP-2 + SDF-1α group (median grade 8; Q1-Q3 7-9; p = 0.0357) than in the low dose BMP-2 group (7; Q1-Q3 5-9) histologically. This study showed that release of BMP-2 and SDF-1α from heparinized MCM scaffolds allows for the reduction of the applied BMP-2 concentration since SDF-1α seems to enhance the osteoinductive potential of BMP-2. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2126-2134, 2016. © 2016 Wiley Periodicals, Inc.

  18. Time, dose and volume factors in interstitial brachytherapy combined with external irradiation for oral tongue carcinoma

    International Nuclear Information System (INIS)

    Yorozu, Atsunori

    1996-01-01

    This is a retrospective analysis of 136 patients with squamous cell carcinoma of stages I and II of the oral tongue who were treated with interstitial brachytherapy alone or in combination with external irradiation between 1976 and 1991. Control of the primary lesion and the occurrence of late complications were analyzed with respect to dose, time and tumor size with the Cox hazard model. The 5-year survival rates for stages I and II were 84.5% and 75.6%. The 5-year primary control rate was 91.3% for stage I and 77.3% for stage II (p 50 Gy compared with a brachytherapy dose 30 mm. Late complications should be reduced by using a spacer, improvements in dental and oral hygiene, and a sophisticated implant method. (author)

  19. The dose-volume relationship of acute small bowel toxicity from concurrent 5-FU-based chemotherapy and radiation therapy for rectal cancer

    International Nuclear Information System (INIS)

    Baglan, Kathy L.; Frazier, Robert C.; Yan Di; Huang, Raywin R.; Martinez, Alvaro A.; Robertson, John M.

    2002-01-01

    Purpose: A direct relationship between the volume of small bowel irradiated and the degree of acute small bowel toxicity experienced during concurrent 5-fluorouracil (5-FU)-based chemoradiotherapy for rectal carcinoma is well recognized but poorly quantified. This study uses three-dimensional treatment-planning tools to more precisely quantify this dose-volume relationship. Methods and Materials: Forty patients receiving concurrent 5-FU-based chemotherapy and pelvic irradiation for rectal carcinoma had treatment-planning CT scans with small bowel contrast. A median isocentric dose of 50.4 Gy was delivered using a posterior-anterior and opposed lateral field arrangement. Bowel exclusion techniques were routinely used, including prone treatment position on a vacuum bag cradle to allow anterior displacement of the abdominal contents and bladder distension. Individual loops of small bowel were contoured on each slice of the planning CT scan, and a small bowel dose-volume histogram was generated for the initial pelvis field receiving 45 Gy. The volume of small bowel receiving each dose between 5 and 40 Gy was recorded at 5-Gy intervals. Results: Ten patients (25%) experienced Common Toxicity Criteria Grade 3+ acute small bowel toxicity. A highly statistically significant association between the development of Grade 3+ acute small bowel toxicity and the volume of small bowel irradiated was found at each dose level. Specific dose-volume threshold levels were found, below which no Grade 3+ toxicity occurred and above which 50-60% of patients developed Grade 3+ toxicity. The volume of small bowel receiving at least 15 Gy (V 15 ) was strongly associated with the degree of toxicity. Univariate analysis of patient and treatment-related factors revealed no other significant predictors of severe toxicity. Conclusions: A strong dose-volume relationship exists for the development of Grade 3+ acute small bowel toxicity in patients receiving concurrent 5-FU-based chemoradiotherapy

  20. Effect of Uniform and Non-uniform High-z Nanoparticles Distribution in Tumor Volume on Dose Enhancement Factor During 192Ir Brachytherapy

    Directory of Open Access Journals (Sweden)

    M Zabihzadeh

    2013-12-01

    Conclusion: increase of atomic number and concentrations of NPs enhance the absorbed dose due to increased possibility of photoelectric phenomena. Non-uniform distribution of NPs underestimated dose compared to uniform distribution; therefore, considering accurate NPs distribution inside the tumor volume is crucial to calculation of dose enhancement. Targeted labeling of NPs for the maximum absorption by tumor and for the minimal penetration into peripheral tissues has potential to increase radiation therapeutic ratio.

  1. Clinical implementation of dose-volume histogram predictions for organs-at-risk in IMRT planning

    International Nuclear Information System (INIS)

    Moore, K L; Appenzoller, L M; Tan, J; Michalski, J M; Thorstad, W L; Mutic, S

    2014-01-01

    True quality control (QC) of the planning process requires quantitative assessments of treatment plan quality itself, and QC in IMRT has been stymied by intra-patient anatomical variability and inherently complex three-dimensional dose distributions. In this work we describe the development of an automated system to reduce clinical IMRT planning variability and improve plan quality using mathematical models that predict achievable OAR DVHs based on individual patient anatomy. These models rely on the correlation of expected dose to the minimum distance from a voxel to the PTV surface, whereby a three-parameter probability distribution function (PDF) was used to model iso-distance OAR subvolume dose distributions. DVH models were obtained by fitting the evolution of the PDF with distance. Initial validation on clinical cohorts of 40 prostate and 24 head-and-neck plans demonstrated highly accurate model-based predictions for achievable DVHs in rectum, bladder, and parotid glands. By quantifying the integrated difference between candidate DVHs and predicted DVHs, the models correctly identified plans with under-spared OARs, validated by replanning all cases and correlating any realized improvements against the predicted gains. Clinical implementation of these predictive models was demonstrated in the PINNACLE treatment planning system by use of existing margin expansion utilities and the scripting functionality inherent to the system. To maintain independence from specific planning software, a system was developed in MATLAB to directly process DICOM-RT data. Both model training and patient-specific analyses were demonstrated with significant computational accelerations from parallelization.

  2. Determination of the optimal statistical uncertainty to perform electron-beam Monte Carlo absorbed dose estimation in the target volume; Determination de l'incertitude statistique optimale pour realiser un calcul de dose dans le volume cible en utilisant la methode de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Isambert, A.; Lefkopoulos, D. [Institut Gustave-Roussy, Medical Physics Dept., 94 - Villejuif (France); Brualla, L. [NCTeam, Strahlenklinik, Universitatsklinikum Essen (Germany); Benkebil, M. [DOSIsoft, 94 - Cachan (France)

    2010-04-15

    Purpose of study Monte Carlo based treatment planning system are known to be more accurate than analytical methods for performing absorbed dose estimation, particularly in and near heterogeneities. However, the required computation time can still be an issue. The present study focused on the determination of the optimum statistical uncertainty in order to minimise computation time while keeping the reliability of the absorbed dose estimation in treatments planned with electron-beams. Materials and methods Three radiotherapy plans (medulloblastoma, breast and gynaecological) were used to investigate the influence of the statistical uncertainty of the absorbed dose on the target volume dose-volume histograms (spinal cord, intra-mammary nodes and pelvic lymph nodes, respectively). Results The study of the dose-volume histograms showed that for statistical uncertainty levels (1 S.D.) above 2 to 3%, the standard deviation of the mean dose in the target volume calculated from the dose-volume histograms increases by at least 6%, reflecting the gradual flattening of the dose-volume histograms. Conclusions This work suggests that, in clinical context, Monte Carlo based absorbed dose estimations should be performed with a maximum statistical uncertainty of 2 to 3%. (authors)

  3. Radioiodine therapy in Graves' disease based on tissue-absorbed dose calculations: effect of pre-treatment thyroid volume on clinical outcome

    International Nuclear Information System (INIS)

    Reinhardt, Michael J.; Joe, Alexius Y.; Mallek, Dirk von; Ezziddin, Samer; Palmedo, Holger; Brink, Ingo; Krause, Thomas M.

    2002-01-01

    This study was performed with three aims. The first was to analyse the effectiveness of radioiodine therapy in Graves' disease patients with and without goitres under conditions of mild iodine deficiency using several tissue-absorbed doses. The second aim was to detect further parameters which might be predictive for treatment outcome. Finally, we wished to determine the deviation of the therapeutically achieved dose from that intended. Activities of 185-2,220 MBq radioiodine were calculated by means of Marinelli's formula to deliver doses of 150, 200 or 300 Gy to the thyroids of 224 patients with Graves' disease and goitres up to 130 ml in volume. Control of hyperthyroidism, change in thyroid volume and thyrotropin-receptor antibodies were evaluated 15±9 months after treatment for each dose. The results were further evaluated with respect to pre-treatment parameters which might be predictive for therapy outcome. Thyroidal radioiodine uptake was measured every day during therapy to determine the therapeutically achieved target dose and its coefficient of variation. There was a significant dose dependency in therapeutic outcome: frequency of hypothyroidism increased from 27.4% after 150 Gy to 67.7% after 300 Gy, while the frequency of persistent hyperthyroidism decreased from 27.4% after 150 Gy to 8.1% after 300 Gy. Patients who became hypothyroid had a maximum thyroid volume of 42 ml and received a target dose of 256±80 Gy. The coefficient of variation for the achieved target dose ranged between 27.7% for 150 Gy and 17.8% for 300 Gy. When analysing further factors which might influence therapeutic outcome, only pre-treatment thyroid volume showed a significant relationship to the result of treatment. It is concluded that a target dose of 250 Gy is essential to achieve hypothyroidism within 1 year after radioiodine therapy in Graves' disease patients with goitres up to 40 ml in volume. Patients with larger goitres might need higher doses. (orig.)

  4. Nuclear criticality safety experiments, calculations, and analyses - 1958 to 1982. Volume 2. Summaries. Complilation of papers from the Transactions of the American Nuclear Society

    International Nuclear Information System (INIS)

    Koponen, B.L.; Hampel, V.E.

    1982-01-01

    This compilation contains 688 complete summaries of papers on nuclear criticality safety as presented at meetings of the American Nuclear Society (ANS). The selected papers contain criticality parameters for fissile materials derived from experiments and calculations, as well as criticality safety analyses for fissile material processing, transport, and storage. The compilation was developed as a component of the Nuclear Criticality Information System (NCIS) now under development at the Lawrence Livermore National Laboratory. The compilation is presented in two volumes: Volume 1 contains a directory to the ANS Transaction volume and page number where each summary was originally published, the author concordance, and the subject concordance derived from the keyphrases in titles. Volume 2 contains-in chronological order-the full-text summaries, reproduced here by permission of the American Nuclear Society from their Transactions, volumes 1-41

  5. Nuclear criticality safety experiments, calculations, and analyses - 1958 to 1982. Volume 2. Summaries. Complilation of papers from the Transactions of the American Nuclear Society

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, B.L.; Hampel, V.E.

    1982-10-21

    This compilation contains 688 complete summaries of papers on nuclear criticality safety as presented at meetings of the American Nuclear Society (ANS). The selected papers contain criticality parameters for fissile materials derived from experiments and calculations, as well as criticality safety analyses for fissile material processing, transport, and storage. The compilation was developed as a component of the Nuclear Criticality Information System (NCIS) now under development at the Lawrence Livermore National Laboratory. The compilation is presented in two volumes: Volume 1 contains a directory to the ANS Transaction volume and page number where each summary was originally published, the author concordance, and the subject concordance derived from the keyphrases in titles. Volume 2 contains-in chronological order-the full-text summaries, reproduced here by permission of the American Nuclear Society from their Transactions, volumes 1-41.

  6. 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

  7. Methods for Reducing Normal Tissue Complication Probabilities in Oropharyngeal Cancer: Dose Reduction or Planning Target Volume Elimination

    Energy Technology Data Exchange (ETDEWEB)

    Samuels, Stuart E.; Eisbruch, Avraham; Vineberg, Karen; Lee, Jae; Lee, Choonik; Matuszak, Martha M.; Ten Haken, Randall K.; Brock, Kristy K., E-mail: kbrock@med.umich.edu

    2016-11-01

    Purpose: Strategies to reduce the toxicities of head and neck radiation (ie, dysphagia [difficulty swallowing] and xerostomia [dry mouth]) are currently underway. However, the predicted benefit of dose and planning target volume (PTV) reduction strategies is unknown. The purpose of the present study was to compare the normal tissue complication probabilities (NTCP) for swallowing and salivary structures in standard plans (70 Gy [P70]), dose-reduced plans (60 Gy [P60]), and plans eliminating the PTV margin. Methods and Materials: A total of 38 oropharyngeal cancer (OPC) plans were analyzed. Standard organ-sparing volumetric modulated arc therapy plans (P70) were created and then modified by eliminating the PTVs and treating the clinical tumor volumes (CTVs) only (C70) or maintaining the PTV but reducing the dose to 60 Gy (P60). NTCP dose models for the pharyngeal constrictors, glottis/supraglottic larynx, parotid glands (PGs), and submandibular glands (SMGs) were analyzed. The minimal clinically important benefit was defined as a mean change in NTCP of >5%. The P70 NTCP thresholds and overlap percentages of the organs at risk with the PTVs (56-59 Gy, vPTV{sub 56}) were evaluated to identify the predictors for NTCP improvement. Results: With the P60 plans, only the ipsilateral PG (iPG) benefited (23.9% vs 16.2%; P<.01). With the C70 plans, only the iPG (23.9% vs 17.5%; P<.01) and contralateral SMG (cSMG) (NTCP 32.1% vs 22.9%; P<.01) benefited. An iPG NTCP threshold of 20% and 30% predicted NTCP benefits for the P60 and C70 plans, respectively (P<.001). A cSMG NTCP threshold of 30% predicted for an NTCP benefit with the C70 plans (P<.001). Furthermore, for the iPG, a vPTV{sub 56} >13% predicted benefit with P60 (P<.001) and C70 (P=.002). For the cSMG, a vPTV{sub 56} >22% predicted benefit with C70 (P<.01). Conclusions: PTV elimination and dose-reduction lowered the NTCP of the iPG, and PTV elimination lowered the NTCP of the cSMG. NTCP thresholds and the

  8. A Varian DynaLog file-based procedure for patient dose-volume histogram-based IMRT QA.

    Science.gov (United States)

    Calvo-Ortega, Juan F; Teke, Tony; Moragues, Sandra; Pozo, Miquel; Casals-Farran, Joan

    2014-03-06

    In the present study, we describe a method based on the analysis of the dynamic MLC log files (DynaLog) generated by the controller of a Varian linear accelerator in order to perform patient-specific IMRT QA. The DynaLog files of a Varian Millennium MLC, recorded during an IMRT treatment, can be processed using a MATLAB-based code in order to generate the actual fluence for each beam and so recalculate the actual patient dose distribution using the Eclipse treatment planning system. The accuracy of the DynaLog-based dose reconstruction procedure was assessed by introducing ten intended errors to perturb the fluence of the beams of a reference plan such that ten subsequent erroneous plans were generated. In-phantom measurements with an ionization chamber (ion chamber) and planar dose measurements using an EPID system were performed to investigate the correlation between the measured dose changes and the expected ones detected by the reconstructed plans for the ten intended erroneous cases. Moreover, the method was applied to 20 cases of clinical plans for different locations (prostate, lung, breast, and head and neck). A dose-volume histogram (DVH) metric was used to evaluate the impact of the delivery errors in terms of dose to the patient. The ionometric measurements revealed a significant positive correlation (R² = 0.9993) between the variations of the dose induced in the erroneous plans with respect to the reference plan and the corresponding changes indicated by the DynaLog-based reconstructed plans. The EPID measurements showed that the accuracy of the DynaLog-based method to reconstruct the beam fluence was comparable with the dosimetric resolution of the portal dosimetry used in this work (3%/3 mm). The DynaLog-based reconstruction method described in this study is a suitable tool to perform a patient-specific IMRT QA. This method allows us to perform patient-specific IMRT QA by evaluating the result based on the DVH metric of the planning CT image (patient

  9. Optimization of total arc degree for stereotactic radiotherapy by using integral biologically effective dose and irradiated volume

    International Nuclear Information System (INIS)

    Lim, Do Hoon; Kim, Dae Yong; Lee, Myung Za; Chun, Ha Chung

    2001-01-01

    To find the optimal values of total arc degree to protect the normal brain tissue from high dose radiation in stereotactic radiotherapy planning. With Xknife-3 planning system and 4 MV linear accelerator, the authors planned under various values of parameters. One isocenter, 12, 20, 30, 40, 50, and 60 mm of collimator diameters, 100 deg, 200 deg, 300 deg, 400 deg, 500 deg, 600 deg, of total arc degrees, and 30 deg or 45 deg of arc intervals were used. After the completion of planning, the plans were compared each other using V 50 (the volume of normal brain that is delivered high dose radiation) and integral biologically effective dose. At 30 deg of arc interval, the values of V 50 had the decreased pattern with the increase of total arc degree in any collimator diameter. At 45 deg arc interval, up to 400 deg of total arc degree, the values of V 50 decreased with the increase of total arc degree, but at 500 deg and 600 deg of total arc degrees, the values increased. At 30 deg of arc interval, integral biologically effective dose showed the decreased pattern with the increase of total arc degree in any collimator diameter. At 45 deg arc interval with less than 40 mm collimator diameter, the integral biologically effective dose decreased with the increase of total arc degree, but with 50 and 60 mm of collimator diameters, up to 400 deg of total arc degree, integral biologically effective dose decreased with the increase of total arc degree, but at 500 deg and 600 deg of total arc degrees, the values increased. In the stereotactic radiotherapy planning for brain lesions, planning with 400 deg of total arc degree is optimal. Especially, when the larger collimator more than 50 mm diameter should be used, the uses of 500 deg and 600 deg of total arc degrees make the increase of V 50 and integral biologically effective dose, Therefore stereotactic radiotherapy planning using 400 deg of total arc degree can increase the therapeutic ratio and produce the effective outcome

  10. Derivation and representation of dose-volume response from large clinical trial data sets: an example from the RADAR prostate radiotherapy trial

    Science.gov (United States)

    Ebert, M. A.; Foo, K.; Haworth, A.; Gulliford, S. L.; Kearvall, R.; Kennedy, A.; Richardson, S.; Krawiec, M.; Stewart, N.; Joseph, D. J.; Denham, J. W.

    2014-03-01

    Large multicentre radiotherapy trials incorporating assessment of multiple outcomes at multiple timepoints can generate extensive datasets. We have investigated graphical techniques for presentation of this data and the associated underlying dose-volume response information, necessary for guiding statistical analyses and translating outcomes to future patient treatments. A relational database was used to archive reviewed plan data for patients accrued to the TROG 03.04 RADAR trial. Viewing software was used to clean and enhance the data. Scripts were developed to export arbitrary dose-histogram data which was combined with clinical toxicity data with a median follow-up of 72 months. Graphical representations of dose-volume response developed include prevalence atlasing, univariate logistic regression and dose-volume-point odds ratios, and continuous cut-point derivation via ROC analysis. These representations indicate variable association of toxicities across structures and time-points.

  11. Disrupting Qualitative Inquiry: Possibilities and Tensions in Educational Research. Critical Qualitative Research. Volume 10

    Science.gov (United States)

    Brown, Ruth Nicole, Ed.; Carducci, Rozana, Ed.; Kuby, Candace R., Ed.

    2014-01-01

    "Disrupting Qualitative Inquiry" is an edited volume that examines the possibilities and tensions encountered by scholars who adopt disruptive qualitative approaches to the study of educational contexts, issues, and phenomena. It presents a collection of innovative and intellectually stimulating chapters which illustrate the potential…

  12. 17 CFR 16.01 - Trading volume, open contracts, prices, and critical dates.

    Science.gov (United States)

    2010-04-01

    ... day the following information separately for futures by commodity and by future, and, for options, by underlying futures contract for options on futures contracts or by underlying physical for options on...; (5) The total volume of futures exchanged for commodities or for derivatives positions which are...

  13. TU-F-CAMPUS-T-05: Dose Escalation to Biological Tumor Volumes of Prostate Cancer Patients Using Gold Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jermoumi, M; Ngwa, W [Department of Physics and Applied Physics, Medical Physics Program, University of Massachusetts Lowell (United States); Department of Radiation Oncology, Dana Farber Cancer Insitute, Brigham and Women’s Hospital, Harvard Medical, Boston, MA (United States); Sajo, E [Department of Physics and Applied Physics, Medical Physics Program, University of Massachusetts Lowell (United States); Houari, K [Department of Radiation Oncology, Dana Farber Cancer Insitute, Brigham and Women’s Hospital, Harvard Medical, Boston, MA (United States)

    2015-06-15

    Purpose: Studies have shown that radiation boosting could help reduce prostate cancer (PCa) recurrence. Biological tumor volumes (BTV) are a high priority for such radiation boosting. The purpose of this study is to investigate the potential of radiation boosting of real patient BTVs using gold nanoparticles (GNP) released from gold-loaded brachytherapy spacers (GBS) during brachytherapy. Methods: The BTVs of 12 patients having prostate adenocarcinoma identified with positron emission tomography (PET) and CT scanner using C-11 labeled tracer [11C]acetate were investigated. The initial GNP concentration and time to achieve a dose enhancement effect (DEF) of 2 was simulated using the freely downloadable software RAID APP. The investigations were carried out for low dose rate (LDR) brachytherapy sources (BTS) described in AAPM Task Group report 43: Cs-131, I-125, and Pd-103. In first case, we used 7 mg/g and 18 mg/g of GNP initial concentrations to estimate the time needed for released GNP to achieve a DEF of 2 for the different BTS, and compare with clinically relevant treatment times. In second case, we calculated the initial concentration of GNPs needed to achieve a DEF of 2 during the time the BTS would typically deliver 50%, 70% and 90% of the total dose. Results: For an initial concentration of 18 mg/g, when using Cs-131, and Pd-103, a DEF of 2 could only be achieved for BTV of 3.3 cm3 and 1 cm3 respectively. Meanwhile a DEF of 2 could be achieved for all 12 BTVs when using I-125. To achieve a DEF of 2 for all patients using Cs-131 and Pd-103, much higher initial concentrations would have to be used than have been typically employed in pre-clinical studies. Conclusion: The I-125 is the most viable BTS that can be employed with GBS to guide dose painting treatment planning for localized PCa.

  14. Effects of local single and fractionated X-ray doses on rat bone marrow blood flow and red blood cell volume

    International Nuclear Information System (INIS)

    Pitkaenen, M.A.; Hopewell, J.W.

    1985-01-01

    Time and dose dependent changes in blood flow and red blood cell volume were studied in the locally irradiated bone marrow of the rat femur after single and fractionated doses of X-rays. With the single dose of 10 Gy the bone marrow blood flow although initially reduced returned to the control levels by seven months after irradiation. With doses >=15 Gy the blood flow was still significantly reduced at seven months. The total dose levels predicted by the nominal standard dose equation for treatments in three, six or nine fractions produced approximately the same degree of reduction in the bone marrow blood flow seven months after the irradiation. However, the fall in the red blood cell volume was from 23 to 37% greater in the three fractions groups compared with that in the nine fractions groups. Using the red blood cell volume as a parameter the nominal standard dose formula underestimated the severity of radiation damage in rat bone marrow at seven months for irradiation with small numbers of large dose fractions. (orig.) [de

  15. Dose-response characteristics of neonatal exposure to genistein on pituitary responsiveness to gonadotropin releasing hormone and volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) in postpubertal castrated female rats.

    Science.gov (United States)

    Faber, K A; Hughes, C L

    1993-01-01

    Estrogen exposure during critical periods of development promotes androgenization of the brain, which is reflected in altered morphology, behavior, and cyclic hormone secretion in females. Previous work in our laboratory demonstrated that neonatal female rats injected with pharmaceutical or naturally occurring estrogens had decreased GnRH-induced LH secretion and increased volume of the SDN-POA as 42 day castrates. The current experiment defines the dose-response characteristics of neonatal exposure to the isoflavonoid phytoestrogen genistein (G) on pituitary sensitivity to GnRH and SDN-POA volume. Litters of rat pups received subcutaneous injections of either corn oil, 1, 10, 100, 200, 400, 500, or 1000 micrograms of G on days 1 to 10 of life. The litters were ovariectomized and weaned on day 21. On day 42 blood was drawn from right atrial catheters immediately prior to, 5, 10, 15, and 30 min following a single injection of 50 ng/kg of GnRH. Only the 10 micrograms dose of G was associated with increased pituitary response to GnRH, while progressive increases in exposure levels of G were associated with decreasing LH secretion. The SDN-POA volume was increased in only the 500 micrograms and 1000 micrograms exposure groups compared to controls. The results confirm that low doses of G have nonandrogenizing, pituitary-sensitizing effects, while higher doses of G mimic the more typical effects of estrogens. The use of both morphologic and physiologic end points more completely defines the reproductive consequences of environmental estrogen exposure during critical periods of CNS development.

  16. Taste and smell disturbances after brain irradiation: a dose-volume histogram analysis of a prospective observational study.

    Science.gov (United States)

    Leyrer, C Marc; Chan, Michael D; Peiffer, Ann M; Horne, Elizabeth; Harmon, Michelle; Carter, Annette F; Hinson, William H; Mirlohi, Susan; Duncan, Susan E; Dietrich, Andrea M; Lesser, Glenn J

    2014-01-01

    Radiation-induced taste and smell disturbances are prevalent in patients receiving brain radiation therapy, although the mechanisms underlying these toxicities are poorly understood. We report the results of a single institution prospective clinical trial aimed at correlating self-reported taste and smell disturbances with radiation dose delivered to defined areas within the brain and nasopharynx. Twenty-two patients with gliomas were enrolled on a prospective observational trial in which patients underwent a validated questionnaire assessing taste and smell disturbances at baseline and at 3 and 6 weeks after commencement of brain radiation therapy. Fourteen patients with glioblastoma, 3 patients with grade 3 gliomas, and 5 patients with low grade gliomas participated. Median dose to tumor volume was 60 Gy (range, 45-60 Gy). Dose-volume histogram (DVH) analysis was performed for specific regions of interest that were considered potential targets of radiation damage, including the thalamus, temporal lobes, nasopharynx, olfactory groove, frontal pole, and periventricular stem cell niche. The %v10 (percent of region of interest receiving 10 Gy), %v40, and %v60 were calculated for each structure. Data from questionnaires and DVH were analyzed using stepwise regression. Twenty of 22 patients submitted evaluable questionnaires that encompassed at least the entire radiation therapy course. Ten of 20 patients reported experiencing some degree of smell disturbance during radiation therapy, and 14 of 20 patients experienced taste disturbances. Patients reporting more severe taste toxicity also reported more severe toxicities with sense of smell (r(2) = 0.60, P < .006). Tumor location in the temporal lobe predicted for increased severity of taste toxicity (F3, 16 = 1.44, P < .06). The nasopharynx was the only structure in which the DVH data predicted the presence of radiation-induced taste changes (r(2) = 0.28, P < .02). Radiation-induced taste toxicity appears to be more

  17. Criticality accident in uranium fuel processing plant. Emergency medical care and dose estimation for the severely overexposed patients

    Energy Technology Data Exchange (ETDEWEB)

    Akashi, Makoto; Ishigure, Nobuhito [National Inst. of Radiological Sciences, Chiba (Japan)

    2000-08-01

    A criticality accident occurred in JCO, a plant for nuclear fuel production in 1999 and three workers were exposed to extremely high-level radiation (neutron and {gamma}-ray). This report describes outlines of the clinical courses and the medical cares for the patients of this accident and the emergent medical system for radiation accident in Japan. One (A) of the three workers of JCO had vomiting and diarrhea within several minutes after the accident and another one (B) had also vomiting within one hour after. Based on these evidences, the exposure dose of A and B were estimated to be more than 8 and 4 GyEq, respectively. Generally, acute radiation syndrome (ARS) is assigned into three phases; prodromal phase, critical or manifestation phase and recovery phase or death. In the prodromal phase, anorexia, nausea, vomiting and diarrhea often develop, whereas the second phase is asymptotic. In the third phase, various syndromes including infection, hemorrhage, dehydration shock and neurotic syndromes are apt to occur. It is known that radiation exposure at 1 Gy or more might induce such acute radiation syndromes. Based on the clinical findings of Chernobyl accident, it has been thought that exposure at 0.5 Gy or more causes a lowering of lymphocyte level and a decrease in immunological activities within 48 hours. Lymphocyte count is available as an indicator for the evaluation of exposure dose in early phase, but not in later phase The three workers of JCO underwent chemical analysis of blood components, chromosomal analysis and analysis of blood {sup 24}Na immediately after the arrival at National Institute of Radiological Sciences via National Mito Hospital specified as the third and the second facility for the emergency medical care system in Japan, respectively. (M.N.)

  18. Intensity modulated radiation therapy (IMRT: differences in target volumes and improvement in clinically relevant doses to small bowel in rectal carcinoma

    Directory of Open Access Journals (Sweden)

    Delclos Marc E

    2011-06-01

    Full Text Available Abstract Background A strong dose-volume relationship exists between the amount of small bowel receiving low- to intermediate-doses of radiation and the rates of acute, severe gastrointestinal toxicity, principally diarrhea. There is considerable interest in the application of highly conformal treatment approaches, such as intensity-modulated radiation therapy (IMRT, to reduce dose to adjacent organs-at-risk in the treatment of carcinoma of the rectum. Therefore, we performed a comprehensive dosimetric evaluation of IMRT compared to 3-dimensional conformal radiation therapy (3DCRT in standard, preoperative treatment for rectal cancer. Methods Using RTOG consensus anorectal contouring guidelines, treatment volumes were generated for ten patients treated preoperatively at our institution for rectal carcinoma, with IMRT plans compared to plans derived from classic anatomic landmarks, as well as 3DCRT plans treating the RTOG consensus volume. The patients were all T3, were node-negative (N = 1 or node-positive (N = 9, and were planned to a total dose of 45-Gy. Pairwise comparisons were made between IMRT and 3DCRT plans with respect to dose-volume histogram parameters. Results IMRT plans had superior PTV coverage, dose homogeneity, and conformality in treatment of the gross disease and at-risk nodal volume, in comparison to 3DCRT. Additionally, in comparison to the 3DCRT plans, IMRT achieved a concomitant reduction in doses to the bowel (small bowel mean dose: 18.6-Gy IMRT versus 25.2-Gy 3DCRT; p = 0.005, bladder (V40Gy: 56.8% IMRT versus 75.4% 3DCRT; p = 0.005, pelvic bones (V40Gy: 47.0% IMRT versus 56.9% 3DCRT; p = 0.005, and femoral heads (V40Gy: 3.4% IMRT versus 9.1% 3DCRT; p = 0.005, with an improvement in absolute volumes of small bowel receiving dose levels known to induce clinically-relevant acute toxicity (small bowel V15Gy: 138-cc IMRT versus 157-cc 3DCRT; p = 0.005. We found that the IMRT treatment volumes were typically larger than that

  19. Blood volume extracted from the critical patient in the first 24 hours after admission.

    Science.gov (United States)

    Maqueda-Palau, M; Pérez-Juan, E

    To calculate the number of analytical tests and blood volume drawn during the first 24hours of admission to the Intensive Care Unit (ICU). To analyse values of basal haemoglobin and at 24hours, relate them to blood loss, weight variation, and scoring system. An observational descriptive pilot study. Variables studied: age, sex, diagnosis on admission, analytical tests extracted, waste quantity before the extraction of samples, total volume blood extracted in 24hours, weight variation, APACHE, SAPS, basal haemoglobin and at 24hours. Statistical analysis with SPSS vs 20.0. Variables correlation sex, weight variation, the number of analytical tests and haemoglobin change. The study included 100 patients. The average number of extractions per patient/day was 7.2 (±2.6). The average waste quantity was 32.61ml (±15.8). The blood volume used for determinations was 48.18ml / 24h (±16.74). The haemoglobin value decreased in the first 24hours of admission, being higher in men (PUnidades Coronarias (SEEIUC). Publicado por Elsevier España, S.L.U. All rights reserved.

  20. International Struggles for Critical Democratic Education. Counterpoints: Studies in the Postmodern Theory of Education. Volume 427

    Science.gov (United States)

    Knoester, Matthew, Ed.

    2012-01-01

    Drawing from rich data, "International Struggles for Critical Democratic Education" profiles teachers, students, and schools struggling to interrupt the reproduction of social inequalities from one generation to the next. International in its nature, the work collected here illustrates how forces of globalization create greater inequalities, and…

  1. SU-E-T-287: Dose Verification On the Variation of Target Volume and Organ at Risk in Preradiation Chemotherapy IMRT for Nasopharyngeal Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X; Kong, L; Wang, J; Hu, W; Chen, Z [Fudan University Shanghai Cancer Center, Shanghai, Shanghai (China)

    2015-06-15

    Purpose: To quantify the target volume and organ at risk of nasopharyngeal carcinoma (NPC) patients with preradiation chemotherapy based on CT scanned during intensity-modulated radiotherapy (IMRT), and recalculate the dose distribution. Methods: Seven patients with NPC and preradiation chemotherapy, treated with IMRT (35 to 37 fractions) were reviewed. Repeat CT scanning was required to all of the patients during the radiotherapy, and the number of repeat CTs varies from 2 to 6. The plan CT and repeat CT were generated by different CT scanner. To ensure crespectively on the same IMPT plan. The real dose distribution was calculated by deformable registration and weighted method in Raystation (v 4.5.1). The fraction of each dose is based on radiotherapy record. The volumetric and dose differences among these images were calculated for nascIpharyngeal tumor and retro-pharyngeal lymph nodes (GTV-NX), neck lymph nodes(GTV-ND), and parotid glands. Results: The volume variation in GTV-NX from CT1 to CT2 was 1.15±3.79%, and in GTV-LN −0.23±4.93%. The volume variation in left parotid from CT1 to CT2 was −6.79±11.91%, and in right parotid −3.92±8.80%. In patient 2, the left parotid volume were decreased remarkably, as a Result, the V30 and V40 of it were increased as well. Conclusion: The target volume of patients with NPC varied lightly during IMRT. It shows that preradiation chemotherapy can control the target volume variation and perform a good dose repeatability. Also, the decreasing volume of parotid in some patient might increase the dose of it, which might course potential complications.

  2. Effect of tumor dose, volume and overall treatment time on local control after radiochemotherapy including MRI guided brachytherapy of locally advanced cervical cancer

    DEFF Research Database (Denmark)

    Tanderup, Kari; Fokdal, Lars Ulrik; Sturdza, Alina

    2016-01-01

    (CTVHR) (p = 0.022, HR = 0.967 per Gy) was significant for local control, whereas increasing CTVHR volume (p = 0.004, HR = 1.017 per cm3), and longer OTT (p = 0.004, HR = 1.023 per day) were associated with worse local control. Histology (p = 0.084), chemotherapy (p = 0.49) and dose rate (p = 1.00) did...... Hazards model was applied to analyze the effect on local control of dose-volume metrics as well as overall treatment time (OTT), dose rate, chemotherapy, and tumor histology. Results With a median follow up of 46 months, 43 local failures were observed. Dose (D90) to the High Risk Clinical Target Volume...... not have significant impact on local control. Separate analyses according to stage of disease showed that dose to CTVHR, residual gross tumor volume (GTVres), and Intermediate Risk CTV (CTVIR) has significant impact on local control. Conclusion CTVHR dose of ⩾85 Gy (D90) delivered in 7 weeks provides 3...

  3. Oak Ridge Health Studies Phase 1 report, Volume 2: Part A, Dose Reconstruction Feasibility Study

    International Nuclear Information System (INIS)

    Bruce, G.M.; Buddenbaum, J.E.; Lamb, J.K.; Widner, T.E.

    1993-09-01

    The Phase I feasibility study has focused on determining the availability of information for estimating exposures of the public to chemicals and radionuclides released as a result of historical operation of the facilities at the Oak Ridge Reservation (ORR). The estimation of such past exposures is frequently called dose reconstruction. The initial project tasks, Tasks 1 and 2 were designed to identify and collect information that documents the history of activities at the ORR that resulted in the release of contamination and to characterize the availability of data that could be used to estimate the magnitude of the contaminant releases or public exposures. A history of operations that are likely to have generated off-site releases has been documented as a result of Task 1 activities. The activities required to perform this task involved the extensive review of historical operation records and interviews with present and past employees as well as other knowledgeable individuals. The investigation process is documented in this report. The Task 1 investigations have led to the documentation of an overview of the activities that have taken place at each of the major complexes, including routine operations, waste management practices, special projects, and accidents and incidents. Historical activities that appear to warrant the highest priority in any further investigations were identified based on their likely association with off-site emissions of hazardous materials as indicated by the documentation reviewed or information obtained in interviews

  4. Personnel neutron dose assessment upgrade: Volume 1, Personnel neutron dosimetry assessment: [Final report

    International Nuclear Information System (INIS)

    Hadlock, D.E.; Brackenbush, L.W.; Griffith, R.V.; Hankins, D.E.; Parkhurst, M.A.; Stroud, C.M.; Faust, L.G.; Vallario, E.J.

    1988-07-01

    This report provides guidance on the characteristics, use, and calibration criteria for personnel neutron dosimeters. The report is applicable for neutrons with energies ranging from thermal to less than 20 MeV. Background for general neutron dosimetry requirements is provided, as is relevant federal regulations and other standards. The characteristics of personnel neutron dosimeters are discussed, with particular attention paid to passive neutron dosimetry systems. Two of the systems discussed are used at DOE and DOE-contractor facilities (nuclear track emulsion and thermoluminescent-albedo) and another (the combination TLD/TED) was recently developed. Topics discussed in the field applications of these dosimeters include their theory of operation, their processing, readout, and interpretation, and their advantages and disadvantages for field use. The procedures required for occupational neutron dosimetry are discussed, including radiation monitoring and the wearing of dosimeters, their exchange periods, dose equivalent evaluations, and the documenting of neutron exposures. The coverage of dosimeter testing, maintenance, and calibration includes guidance on the selection of calibration sources, the effects of irradiation geometries, lower limits of detectability, fading, frequency of calibration, spectrometry, and quality control. 49 refs., 6 figs., 8 tabs

  5. Oak Ridge Health Studies Phase 1 report, Volume 2: Part C, Dose Reconstruction Feasibility Study

    International Nuclear Information System (INIS)

    DaMassa, C.L.; Widner, T.E.

    1993-09-01

    A significant number of information sources have been identified that are relevant to historical locations and activities of populations potentially affected by releases from the Oak Ridge Reservation. The information that has been reviewed as part of this Task 5 investigation has shown that numerous residences and farms have historically been present near the ORR boundary and that a variety of land uses and recreational activities have been practiced. Based on this information alone, it would appear that many routes of off-site exposure could have been plausible. Most of the available published information addresses demographic and land use data on a regional or county-wide basis over fairly broad time periods. The information sources that are most readily available do not support direct evaluation of potential exposure pathways at specific geographic locations near the Oak Ridge facilities at specific points in time. A number of information sources have been identified that can provide demography and land use information more specific to locations and time periods that are identified to be of interest. Examples of data sources in this category include individual USGS topographic maps, aerial photographs, lowest-level census tract data, and interviews with long-time local residents. However, specific release events and periods of interest should be identified prior to attempts to collect more specific demographic or land use information for actual dose reconstruction

  6. Dose-volume analysis of predictors for chronic rectal toxicity after treatment of prostate cancer with adaptive image-guided radiotherapy

    International Nuclear Information System (INIS)

    Vargas, Carlos; Martinez, Alvaro; Kestin, Larry L.; Yan Di; Grills, Inga; Brabbins, Donald S.; Lockman, David M.; Liang Jian; Gustafson, Gary S.; Chen, Peter Y.; Vicini, Frank A.; Wong, John W.

    2005-01-01

    Purpose We analyzed our experience treating localized prostate cancer with image-guided off-line correction with adaptive high-dose radiotherapy (ART) in our Phase II dose escalation study to identify factors predictive of chronic rectal toxicity. Materials and Methods From 1999-2002, 331 patients with clinical stage T1-T3N0M0 prostate cancer were prospectively treated in our Phase II 3D conformal dose escalation ART study to a median dose of 75.6 Gy (range, 63.0-79.2 Gy), minimum dose to confidence limited-planning target volume (cl-PTV) in 1.8 Gy fractions (median isocenter dose = 79.7 Gy). Seventy-four patients (22%) also received neoadjuvant/adjuvant androgen deprivation therapy. A patient-specific cl-PTV was constructed using 5 computed tomography scans and 4 sets of electronic portal images by applying an adaptive process to assure target accuracy and minimize PTV margin. For each case, the rectum (rectal solid) was contoured from the sacroiliac joints or rectosigmoid junction (whichever was higher) to the anal verge or ischial tuberosities (whichever was lower), with a median volume of 81.2 cc. The rectal wall was defined using the rectal solid with an individualized 3-mm wall thickness (median volume = 29.8 cc). Rectal wall dose-volume histogram was used to determine the prescribed dose. Toxicity was quantified using the National Cancer Institute Common Toxicity Criteria 2.0. Multiple dose-volume endpoints were evaluated for their association with chronic rectal toxicity. Results Median follow-up was 1.6 years. Thirty-four patients (crude rate 10.3%) experienced Grade 2 chronic rectal toxicity at a median interval of 1.1 years. Nine patients (crude rate = 2.7%) experienced Grade ≥3 chronic rectal toxicity (1 was Grade 4) at a median interval of 1.2 years. The 3-year rates of Grade ≥2 and Grade ≥3 chronic rectal toxicity were 20% and 4%, respectively. Acute toxicity predicted for chronic: Acute Grade 2-3 rectal toxicity (p 40% respectively. The volume

  7. Radiobiological restrictions and tolerance doses of repeated single-fraction hdr-irradiation of intersecting small liver volumes for recurrent hepatic metastases

    Directory of Open Access Journals (Sweden)

    Wust Peter

    2010-05-01

    Full Text Available Abstract Background To assess radiobiological restrictions and tolerance doses as well as other toxic effects derived from repeated applications of single-fraction high dose rate irradiation of small liver volumes in clinical practice. Methods Twenty patients with liver metastases were treated repeatedly (2 - 4 times at identical or intersecting locations by CT-guided interstitial brachytherapy with varying time intervals. Magnetic resonance imaging using the hepatocyte selective contrast media Gd-BOPTA was performed before and after treatment to determine the volume of hepatocyte function loss (called pseudolesion, and the last acquired MRI data set was merged with the dose distributions of all administered brachytherapies. We calculated the BED (biologically equivalent dose for a single dose d = 2 Gy for different α/β values (2, 3, 10, 20, 100 based on the linear-quadratic model and estimated the tolerance dose for liver parenchyma D90 as the BED exposing 90% of the pseudolesion in MRI. Results The tolerance doses D90 after repeated brachytherapy sessions were found between 22 - 24 Gy and proved only slightly dependent on α/β in the clinically relevant range of α/β = 2 - 10 Gy. Variance analysis showed a significant dependency of D90 with respect to the intervals between the first irradiation and the MRI control (p 90 and the pseudolesion's volume. No symptoms of liver dysfunction or other toxic effects such as abscess formation occurred during the follow-up time, neither acute nor on the long-term. Conclusions Inactivation of liver parenchyma occurs at a BED of approx. 22 - 24 Gy corresponding to a single dose of ~10 Gy (α/β ~ 5 Gy. This tolerance dose is consistent with the large potential to treat oligotopic and/or recurrent liver metastases by CT-guided HDR brachytherapy without radiation-induced liver disease (RILD. Repeated small volume irradiation may be applied safely within the limits of this study.

  8. Optimization of the fractionated irradiation scheme considering physical doses to tumor and organ at risk based on dose–volume histograms

    International Nuclear Information System (INIS)

    Sugano, Yasutaka; Mizuta, Masahiro; Takao, Seishin; Shirato, Hiroki; Sutherland, Kenneth L.; Date, Hiroyuki

    2015-01-01

    Purpose: Radiotherapy of solid tumors has been performed with various fractionation regimens such as multi- and hypofractionations. However, the ability to optimize the fractionation regimen considering the physical dose distribution remains insufficient. This study aims to optimize the fractionation regimen, in which the authors propose a graphical method for selecting the optimal number of fractions (n) and dose per fraction (d) based on dose–volume histograms for tumor and normal tissues of organs around the tumor. Methods: Modified linear-quadratic models were employed to estimate the radiation effects on the tumor and an organ at risk (OAR), where the repopulation of the tumor cells and the linearity of the dose-response curve in the high dose range of the surviving fraction were considered. The minimization problem for the damage effect on the OAR was solved under the constraint that the radiation effect on the tumor is fixed by a graphical method. Here, the damage effect on the OAR was estimated based on the dose–volume histogram. Results: It was found that the optimization of fractionation scheme incorporating the dose–volume histogram is possible by employing appropriate cell surviving models. The graphical method considering the repopulation of tumor cells and a rectilinear response in the high dose range enables them to derive the optimal number of fractions and dose per fraction. For example, in the treatment of prostate cancer, the optimal fractionation was suggested to lie in the range of 8–32 fractions with a daily dose of 2.2–6.3 Gy. Conclusions: It is possible to optimize the number of fractions and dose per fraction based on the physical dose distribution (i.e., dose–volume histogram) by the graphical method considering the effects on tumor and OARs around the tumor. This method may stipulate a new guideline to optimize the fractionation regimen for physics-guided fractionation

  9. The software program Peridose to calculate the fetal dose or dose to other critical structures outside the target area in radiation therapy

    International Nuclear Information System (INIS)

    Giessen, P.H. van der

    2001-01-01

    An accurate estimate of the dose outside the target area is of utmost importance when pregnant patients have to undergo radiotherapy, something that occurs in every radiotherapy department once in a while. Such peripheral doses (PD) are also of interest for late effects risk estimations for doses to specific organs as well as estimations of dose to pacemakers. A software program, Peridose, is described to allow easy calculation of this peripheral dose. The calculation is based on data from many publications on peripheral dose measurements, including those by the author. Clinical measurements have shown that by using data averaged over many measurements and different machine types PDs can be estimated with an accuracy of ± 60% (2 standard deviations). The program allows easy and fairly accurate estimates of peripheral doses in patients. Further development to overcome some of the constraints and limitations is desirable. The use of average data is to be preferred if general applicability is to be maintained. (author)

  10. Critical joints in large composite primary aircraft structures. Volume 2: Technology demonstration test report

    Science.gov (United States)

    Bunin, Bruce L.

    1985-01-01

    A program was conducted to develop the technology for critical structural joints in composite wing structure that meets all the design requirements of a 1990 commercial transport aircraft. The results of four large composite multirow bolted joint tests are presented. The tests were conducted to demonstrate the technology for critical joints in highly loaded composite structure and to verify the analytical methods that were developed throughout the program. The test consisted of a wing skin-stringer transition specimen representing a stringer runout and skin splice on the wing lower surface at the side of the fuselage attachment. All tests were static tension tests. The composite material was Toray T-300 fiber with Ciba-Geigy 914 resin in 10 mil tape form. The splice members were metallic, using combinations of aluminum and titanium. Discussions are given of the test article, instrumentation, test setup, test procedures, and test results for each of the four specimens. Some of the analytical predictions are also included.

  11. Intensity modulated radiotherapy for localized prostate cancer: rigid compliance to dose-volume constraints as a warranty of acceptable toxicity?

    International Nuclear Information System (INIS)

    Chen, Michael J; Nadalin, Wladmir; Weltman, Eduardo; Hanriot, Rodrigo M; Luz, Fábio P; Cecílio, Paulo J; Cruz, José C da; Moreira, Frederico R; Santos, Adriana S; Martins, Lidiane C

    2007-01-01

    To report the toxicity after intensity modulated radiotherapy (IMRT) for patients with localized prostate cancer, as a sole treatment or after radical prostatectomy. Between August 2001 and December 2003, 132 patients with prostate cancer were treated with IMRT and 125 were evaluable to acute and late toxicity analysis, after a minimum follow-up time of one year. Clinical and treatment data, including normal tissue dose-volume histogram (DVH) constraints, were reviewed. Gastro-intestinal (GI) and genito-urinary (GU) signs and symptoms were evaluated according to the Radiation Therapy Oncology Group (RTOG) toxicity scales. Median prescribed dose was 76 Gy. Median follow-up time was of 26.1 months. From the 125 patients, 73 (58.4%) presented acute Grade 1 or Grade 2 GI and 97 (77.2%) presented acute Grade 1 or Grade 2 GU toxicity. Grade 3 GI acute toxicity occurred in only 2 patients (1.6%) and Grade 3 GU acute toxicity in only 3 patients (2.4%). Regarding Grade 1 and 2 late toxicity, 26 patients (20.8%) and 21 patients (16.8%) presented GI and GU toxicity, respectively. Grade 2 GI late toxicity occurred in 6 patients (4.8%) and Grade 2 GU late toxicity in 4 patients (3.2%). None patient presented any Grade 3 or higher late toxicity. Non-conformity to DVH constraints occurred in only 11.2% of treatment plans. On univariate analysis, no significant risk factor was identified for Grade 2 GI late toxicity, but mean dose delivered to the PTV was associated to higher Grade 2 GU late toxicity (p = 0.042). IMRT is a well tolerable technique for routine treatment of localized prostate cancer, with short and medium-term acceptable toxicity profiles. According to the data presented here, rigid compliance to DHV constraints might prevent higher incidences of normal tissue complication

  12. Impact of image denoising on image quality, quantitative parameters and sensitivity of ultra-low-dose volume perfusion CT imaging

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Ahmed E. [RWTH Aachen University, Department of Diagnostic and Interventional Neuroradiology, Aachen (Germany); Eberhard Karls University Tuebingen, University Hospital Tuebingen, Department for Diagnostic and Interventional Radiology, Tuebingen (Germany); Brockmann, Carolin; Afat, Saif; Pjontek, Rastislav; Nikoubashman, Omid; Brockmann, Marc A.; Wiesmann, Martin [RWTH Aachen University, Department of Diagnostic and Interventional Neuroradiology, Aachen (Germany); Yang, Zepa; Kim, Changwon [Seoul National University, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Suwon (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Nikolaou, Konstantin [Eberhard Karls University Tuebingen, University Hospital Tuebingen, Department for Diagnostic and Interventional Radiology, Tuebingen (Germany); Kim, Jong Hyo [Seoul National University, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Suwon (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Advanced Institute of Convergence Technology, Center for Medical-IT Convergence Technology Research, Suwon (Korea, Republic of); Seoul National University Hospital, Department of Radiology, Seoul (Korea, Republic of)

    2016-01-15

    To examine the impact of denoising on ultra-low-dose volume perfusion CT (ULD-VPCT) imaging in acute stroke. Simulated ULD-VPCT data sets at 20 % dose rate were generated from perfusion data sets of 20 patients with suspected ischemic stroke acquired at 80 kVp/180 mAs. Four data sets were generated from each ULD-VPCT data set: not-denoised (ND); denoised using spatiotemporal filter (D1); denoised using quanta-stream diffusion technique (D2); combination of both methods (D1 + D2). Signal-to-noise ratio (SNR) was measured in the resulting 100 data sets. Image quality, presence/absence of ischemic lesions, CBV and CBF scores according to a modified ASPECTS score were assessed by two blinded readers. SNR and qualitative scores were highest for D1 + D2 and lowest for ND (all p ≤ 0.001). In 25 % of the patients, ND maps were not assessable and therefore excluded from further analyses. Compared to original data sets, in D2 and D1 + D2, readers correctly identified all patients with ischemic lesions (sensitivity 1.0, kappa 1.0). Lesion size was most accurately estimated for D1 + D2 with a sensitivity of 1.0 (CBV) and 0.94 (CBF) and an inter-rater agreement of 1.0 and 0.92, respectively. An appropriate combination of denoising techniques applied in ULD-VPCT produces diagnostically sufficient perfusion maps at substantially reduced dose rates as low as 20 % of the normal scan. (orig.)

  13. A volume-equivalent spherical necrosis-tumor-normal liver model for estimating absorbed dose in yttrium-90 microsphere therapy.

    Science.gov (United States)

    Wu, Chin-Hui; Liao, Yi-Jen; Lin, Tzung-Yi; Chen, Yu-Cheng; Sun, Shung-Shung; Liu, Yen-Wan Hsueh; Hsu, Shih-Ming

    2016-11-01

    Primary hepatocellular carcinoma and metastatic liver tumors are highly malignant tumors in Asia. The incidence of fatal liver cancer is also increasing in the United States. The aim of this study was to establish a spherical tumor model and determine its accuracy in predicting the absorbed dose in yttrium-90 (Y-90) microsphere therapy for liver cancer. Liver morphology can be approximated by a spherical model comprising three concentric regions representing necrotic, tumor, and normal liver tissues. The volumes of these three regions represent those in the actual liver. A spherical tumor model was proposed to calculate the absorbed fractions in the spherical tumor, necrotic, and normal tissue regions. The THORplan treatment planning system and Monte Carlo N-particle extended codes were used for this spherical tumor model. Using the volume-equivalent method, a spherical tumor model was created to calculate the total absorbed fraction [under different tumor-to-healthy-liver ratios (TLRs)]. The patient-specific model (THORplan) results were used to verify the spherical tumor model results. The results for both the Y-90 spectrum and the Y-90 mean energy indicated that the absorbed fraction was a function of the tumor radius and mass. The absorbed fraction increased with tumor radius. The total absorbed fractions calculated using the spherical tumor model for necrotic, liver tumor, and normal liver tissues were in good agreement with the THORplan results, with differences of less than 3% for TLRs of 2-5. The results for the effect of TLR indicate that for the same tumor configuration, the total absorbed fraction decreased with increasing TLR; for the same shell tumor thickness and TLR, the total absorbed fraction was approximately constant; and for tumors with the same radius, the total fraction absorbed by the tumor increased with the shell thickness. The results from spherical tumor models with different tumor-to-healthy-liver ratios were highly consistent with the

  14. The impact of environmental conditions on human performance: A critical review of the literature. Volume 2

    International Nuclear Information System (INIS)

    Echeverria, D.; Barnes, V.; Bittner, A.

    1994-09-01

    The Battelle Human Affairs Research Centers (HARC) conducted a comprehensive review of the technical literature regarding the impact of environmental conditions on human performance applicable to nuclear power plant workers. The environmental conditions considered were vibration, noise, heat, cold, and light. Research staff identified potential human performance deficits along a continuum of increasing occupational exposure, ranging from deficits that occur at low exposures to deficits that occur at high exposures. Specific deficits were included in the review if scientists demonstrated the exposure caused an effect, using sound methodology. The levels associated with each deficit were then compared to the protection afforded by existing occupational exposure standards. Volume 2 presents several conclusions regarding the applicability of the research literature to environmental conditions in nuclear power plants. The findings presented suggest that occupational standards for vibration, noise, and heat, which were developed to protect health, are inadequate for preventing deficits in cognitive or motor performance in tasks likely to be performed in nuclear power plants. Also, there is little information in the literature on simultaneous conditions; for example, the effects of simultaneous exposure to heat and noise on cognition require more research. As many exposures in nuclear power plants will be simultaneous, this limitation should be kept in mind when using Volume 1

  15. Ultra-low-volume space sprays in mosquito control: a critical review.

    Science.gov (United States)

    Bonds, J A S

    2012-06-01

    The availability of tools to control mosquito (Diptera:Culicidae) vectors that transmit disease is often limited by a variety of economic, environmental and social issues. In emergency conditions (epidemics, hurricanes, floods etc.), the application of pesticides as space sprays (either by ground or air) is the common method of choice in order to rapidly limit adult local mosquito production in the affected area. Space spray application now employs ultra-low-volume technology for the control of adult mosquitoes. However, the use of space sprays often raises social and environmental concerns by the general public that is served. This review will define and illustrate modern ultra-low-volume technology for the purpose of application as a space spray, as well as describing the engineering controls that have been developed to minimize the environmental impact. The primary social concern is validity and efficacy of application. To address this point, the review will attempt to synthesize the global literature to address the effectiveness of space sprays to significantly impact mosquito vectors in relation to human disease. © 2012 The Author. Medical and Veterinary Entomology © 2012 The Royal Entomological Society.

  16. SU-F-T-128: Dose-Volume Constraints for Particle Therapy Treatment Planning

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, R; Smith, W; Hendrickson, K; Meyer, J; Cao, N; Lee, E; Gopan, O; Sandison, G; Parvathaneni, U; Laramore, G [University of Washington, Seattle, WA (United States)

    2016-06-15

    Purpose: Determine equivalent Organ at Risk (OAR) tolerance dose (TD) constraints for MV x-rays and particle therapy. Methods: Equivalent TD estimates for MV x-rays are determined from an isoeffect, regression-analysis of published and in-house constraints for various fractionation schedules (n fractions). The analysis yields an estimate of (α/β) for an OAR. To determine equivalent particle therapy constraints, the MV x-ray TD(n) values are divided by the RBE for DSB induction (RBE{sub DSB}) or cell survival (RBE{sub S}). Estimates of (RBE{sub DSB}) are computed using the Monte Carlo Damage Simulation, and estimates of RBES are computed using the Repair-Misrepair-Fixation (RMF) model. A research build of the RayStation™ treatment planning system implementing the above model is used to estimate (RBE{sub DSB}) for OARs of interest in 16 proton therapy patient plans (head and neck, thorax, prostate and brain). Results: The analysis gives an (α/β) estimate of about 20 Gy for the trachea and heart and 2–4 Gy for the esophagus, spine, and brachial plexus. Extrapolation of MV x-ray constraints (n = 1) to fast neutrons using RBE{sub DSB} = 2.7 are in excellent agreement with clinical experience (n = 10 to 20). When conventional (n > 30) x-ray treatments are used as the reference radiation, fast neutron RBE increased to a maximum of 6. For comparison to a constant RBE of 1.1, the RayStation™ analysis gave estimates of proton RBE{sub DSB} from 1.03 to 1.33 for OARs of interest. Conclusion: The presented system of models is a convenient formalism to synthesize from multiple sources of information a set of self-consistent plan constraints for MV x-ray and hadron therapy treatments. Estimates of RBE{sub DSB} from the RayStation™ analysis differ substantially from 1.1 and vary among patients and treatment sites. A treatment planning system that incorporates patient and anatomy-specific corrections in proton RBE would create opportunities to increase the therapeutic

  17. Pilot study in the treatment of endometrial carcinoma with 3D image-based high-dose-rate brachytherapy using modified Heyman packing: Clinical experience and dose-volume histogram analysis

    International Nuclear Information System (INIS)

    Weitmann, Hajo Dirk; Poetter, Richard; Waldhaeusl, Claudia; Nechvile, Elisabeth; Kirisits, Christian; Knocke, Tomas Hendrik

    2005-01-01

    Purpose: The aim of this study was to evaluate dose distribution within uterus (clinical target volume [CTV]) and tumor (gross tumor volume [GTV]) and the resulting clinical outcome based on systematic three-dimensional treatment planning with dose-volume adaptation. Dose-volume assessment and adaptation in organs at risk and its impact on side effects were investigated in parallel. Methods and Materials: Sixteen patients with either locally confined endometrial carcinoma (n = 15) or adenocarcinoma of uterus and ovaries after bilateral salpingo-oophorectomy (n = 1) were included. Heyman packing was performed with mean 11 Norman-Simon applicators (3-18). Three-dimensional treatment planning based on computed tomography (n = 29) or magnetic resonance imaging (n = 18) was done in all patients with contouring of CTV, GTV, and organs at risk. Dose-volume adaptation was achieved by dwell location and time variation (intensity modulation). Twelve patients treated with curative intent received five to seven fractions of high-dose-rate brachytherapy (7 Gy per fraction) corresponding to a total dose of 60 Gy (2 Gy per fraction and α/β of 10 Gy) to the CTV. Four patients had additional external beam radiotherapy (range, 10-40 Gy). One patient had salvage brachytherapy and 3 patients were treated with palliative intent. A dose-volume histogram analysis was performed in all patients. On average, 68% of the CTV and 92% of the GTV were encompassed by the 60 Gy reference volume. Median minimum dose to 90% of CTV and GTV (D90) was 35.3 Gy and 74 Gy, respectively. Results: All patients treated with curative intent had complete remission (12/12). After a median follow-up of 47 months, 5 patients are alive without tumor. Seven patients died without tumor from intercurrent disease after median 22 months. The patient with salvage treatment had a second local recurrence after 27 months and died of endometrial carcinoma after 57 months. In patients treated with palliative intent

  18. Analysis of dose-volume parameters predicting radiation pneumonitis in patients with esophageal cancer treated with 3D-conformal radiation therapy or IMRT.

    Science.gov (United States)

    Kumar, Gaurav; Rawat, Sheh; Puri, Abhishek; Sharma, Manoj Kumar; Chadha, Pranav; Babu, Anand Giri; Yadav, Girigesh

    2012-01-01

    Multimodality therapy for esophageal cancer can cause various kinds of treatment-related sequelae, especially pulmonary toxicities. This prospective study aims to investigate the clinical and dosimetric parameters predicting lung injury in patients undergoing radiation therapy for esophageal cancer. Forty-five esophageal cancer patients were prospectively analyzed. The pulmonary toxicities (or sequelae) were evaluated by comparing chest X-ray films, pulmonary function tests and symptoms caused by pulmonary damage before and after treatment. All patients were treated with either three-dimensional radiotherapy (3DCRT) or with intensity-modulated radiotherapy (IMRT). The planning dose volume histogram was used to compute the lung volumes receiving more than 5, 10, 20 and 30 Gy (V5, V10, V20, V30) and mean lung dose. V20 was larger in the IMRT group than in the 3DCRT group (p = 0.002). V20 (>15%) and V30 (>20%) resulted in a statistically significant increase in the occurrence of chronic pneumonitis (p = 0.03) and acute pneumonitis (p = 0.007), respectively. The study signifies that a larger volume of lung receives lower doses because of multiple beam arrangement and a smaller volume of lung receives higher doses because of better dose conformity in IMRT plans. Acute pneumonitis correlates more with V30 values, whereas chronic pneumonitis was predominantly seen in patients with higher V20 values.

  19. Laser-written binary OMOG photomasks for high-volume non-critical 193-nm photolithographic layers

    Science.gov (United States)

    Rivière, Rémi; Gopalakrishnan, Selvi; Mazur, Martin; Öner, Nevzat; Mühle, Sven; Seltmann, Rolf

    2014-10-01

    Photomasks are key elements of photolithographic processes, implying that their degradation must be reliably monitored and strongly mitigated. Indeed, the photo-induced oxidation of Cr in Cr On Glass (COG) photomasks and the concomitant electrostatic-field migration present in high-volume production using 193-nm photolithographic scanners severely deteriorate the pattern transfer quality, therefore limiting the lifetime of these reticles. To moderate this effect, Opaque MoSi On Glass (OMOG) photomasks, significantly less prone to such degradation, are currently being massively used in leading-edge microfabrication flows. The type of mask fabrication process normally used involving ebeam writing is however not adapted for non-critical photolithographic layers that do not yet benefit from its inherent performances but still suffer from its high cost and its long processing time. It is therefore proposed in this work to combine the simplicity of laser writing and the resistance of MoSi to degradation by using laser-written binary OMOG photomasks for the non-critical layers (e.g. ion-implantation) of a 28-nm production flow. To evaluate one of this new reticle, its pattern transfer fidelity is compared to the one of a laser-written binary COG mask already qualified for production from a photolithographic quality perspective, both masks being treated using the same optical proximity correction (OPC) model. Dispersive and dissipative properties, critical dimension uniformity, pattern linearity and pattern proximity are directly measured on wafer level, subsequently revealing that both photomasks match in terms of OPC parameters. The utilized OPC model is moreover proven robust against the use of both types of masks, consequently making the conversion from COG to OMOG particularly simple. These experimental results therefore qualify the new mask fabrication type and pave the way for a major utilization in high-volume production.

  20. Consensus statement of the ESICM task force on colloid volume therapy in critically ill patients

    DEFF Research Database (Denmark)

    Reinhart, Konrad; Perner, Anders; Sprung, Charles L

    2012-01-01

    PURPOSE: Colloids are administered to more patients than crystalloids, although recent evidence suggests that colloids may possibly be harmful in some patients. The European Society of Intensive Care Medicine therefore assembled a task force to compile consensus recommendations based on the current...... best evidence for the safety and efficacy of the currently most frequently used colloids--hydroxyethyl starches (HES), gelatins and human albumin. METHODS: Meta-analyses, systematic reviews and clinical studies of colloid use were evaluated for the treatment of volume depletion in mixed intensive care...... unit (ICU), cardiac surgery, head injury, sepsis and organ donor patients. Clinical endpoints included mortality, kidney function and bleeding. The relevance of concentration and dosage was also assessed. Publications from 1960 until May 2011 were included. The quality of available evidence...

  1. Assessment of dose-volume histograms in brachytherapy 3D high-rate; Evaluacion de los histogramas dosis volumen en braquiterapia de alta tasa 3D

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Barrado, A.; Tripero Oter, J.; Sanchez Jimenez, E.; Sanchez-Reyes, A.

    2013-07-01

    The use of systems of treatment planning using 3D reconstruction algorithms are becoming more frequent in brachytherapy treatments. The implementation of these systems entails great qualitative and quantitative procedural changes in the way to evaluate the clinical dosimetry about the 2D classical systems. This paper describes the experience of our Centre in employment and prescription dose using histograms dose-volume in the treatment of brachytherapy of high rate. (Author)

  2. Quantitative in vivo assessment of radiation injury of the liver using Gd-EOB-DTPA enhanced MRI: tolerance dose of small liver volumes

    Directory of Open Access Journals (Sweden)

    Pech Maciej

    2011-04-01

    Full Text Available Abstract Backround Hepatic radiation toxicity restricts irradiation of liver malignancies. Better knowledge of hepatic tolerance dose is favourable to gain higher safety and to optimize radiation regimes in radiotherapy of the liver. In this study we sought to determine the hepatic tolerance dose to small volume single fraction high dose rate irradiation. Materials and methods 23 liver metastases were treated by CT-guided interstitial brachytherapy. MRI was performed 3 days, 6, 12 and 24 weeks after therapy. MR-sequences were conducted with T1-w GRE enhanced by hepatocyte-targeted Gd-EOB-DTPA. All MRI data sets were merged with 3D-dosimetry data. The reviewer indicated the border of hypointensity on T1-w images (loss of hepatocyte function or hyperintensity on T2-w images (edema. Based on the volume data, a dose-volume-histogram was calculated. We estimated the threshold dose for edema or function loss as the D90, i.e. the dose achieved in at least 90% of the pseudolesion volume. Results At six weeks post brachytherapy, the hepatocyte function loss reached its maximum extending to the former 9.4Gy isosurface in median (i.e., ≥9.4Gy dose exposure led to hepatocyte dysfunction. After 12 and 24 weeks, the dysfunctional volume had decreased significantly to a median of 11.4Gy and 14Gy isosurface, respectively, as a result of repair mechanisms. Development of edema was maximal at six weeks post brachytherapy (9.2Gy isosurface in median, and regeneration led to a decrease of the isosurface to a median of 11.3Gy between 6 and 12 weeks. The dose exposure leading to hepatocyte dysfunction was not significantly different from the dose provoking edema. Conclusion Hepatic injury peaked 6 weeks after small volume irradiation. Ongoing repair was observed up to 6 months. Individual dose sensitivity may differ as demonstrated by a relatively high standard deviation of threshold values in our own as well as all other published data.

  3. Aggravation of dyspnea in stage - non-small cell lung cancer patients following stereotactic body radiotherapy: Is there a dose-volume dependency?

    International Nuclear Information System (INIS)

    Paludan, Merete; Grau, Cai; Hoeyer, Morten; Traberg Hansen, Anders; Petersen, Joergen

    2006-01-01

    In SBRT for NSCLC, highly potent radiation doses are delivered to patients with frequent pre-irradiatory compromise of pulmonary function. For the risk of pulmonary toxicity to be minimized during SBRT planning, data on its dose-volume dependency is needed. In the present study, we analyse the association of dose-volume histogram parameters with changes in dyspnea. The study concerns 28 medically inoperable stage I NSCLC patients that received SBRT at our department between 2000 and 2003. A central dose of 45 Gy/3 fractions was delivered in 5-8 days. WHO toxicity scoring of dyspnea was prospectively performed at baseline and during a 6-month follow-up post-SBRT. DVH parameters for pulmonary tissue were retrieved from the 3-D dose distributions. Aggravated dyspnea was registered in 11 patients (40%). We found no association between DVH parameters and changes in dyspnea. Nor did we find any consistent temporal variations of dyspnea after SBRT. We identified COPD as the factor showing the closest association with aggravation of dyspnea. The observed aggravation of dyspnea following SBRT reflects habitual exacerbations of COPD rather than treatment-related toxicity. Concern about pulmonary toxicity should not be prohibitive for future studies targeting limitations to dose and volume

  4. Aggravation of dyspnea in stage - non-small cell lung cancer patients following stereotactic body radiotherapy: Is there a dose-volume dependency?

    Energy Technology Data Exchange (ETDEWEB)

    Paludan, Merete; Grau, Cai; Hoeyer, Morten [Aarhus Univ. Hospital (Denmark). Dept. of Oncology; Traberg Hansen, Anders; Petersen, Joergen [Aarhus Univ. Hospital (Denmark). Dept. of Medical Physics

    2006-09-15

    In SBRT for NSCLC, highly potent radiation doses are delivered to patients with frequent pre-irradiatory compromise of pulmonary function. For the risk of pulmonary toxicity to be minimized during SBRT planning, data on its dose-volume dependency is needed. In the present study, we analyse the association of dose-volume histogram parameters with changes in dyspnea. The study concerns 28 medically inoperable stage I NSCLC patients that received SBRT at our department between 2000 and 2003. A central dose of 45 Gy/3 fractions was delivered in 5-8 days. WHO toxicity scoring of dyspnea was prospectively performed at baseline and during a 6-month follow-up post-SBRT. DVH parameters for pulmonary tissue were retrieved from the 3-D dose distributions. Aggravated dyspnea was registered in 11 patients (40%). We found no association between DVH parameters and changes in dyspnea. Nor did we find any consistent temporal variations of dyspnea after SBRT. We identified COPD as the factor showing the closest association with aggravation of dyspnea. The observed aggravation of dyspnea following SBRT reflects habitual exacerbations of COPD rather than treatment-related toxicity. Concern about pulmonary toxicity should not be prohibitive for future studies targeting limitations to dose and volume.

  5. Assessment of dedicated low-dose cardiac micro-CT reconstruction algorithms using the left ventricular volume of small rodents as a performance measure

    International Nuclear Information System (INIS)

    Maier, Joscha; Sawall, Stefan; Kachelrieß, Marc

    2014-01-01

    Purpose: Phase-correlated microcomputed tomography (micro-CT) imaging plays an important role in the assessment of mouse models of cardiovascular diseases and the determination of functional parameters as the left ventricular volume. As the current gold standard, the phase-correlated Feldkamp reconstruction (PCF), shows poor performance in case of low dose scans, more sophisticated reconstruction algorithms have been proposed to enable low-dose imaging. In this study, the authors focus on the McKinnon-Bates (MKB) algorithm, the low dose phase-correlated (LDPC) reconstruction, and the high-dimensional total variation minimization reconstruction (HDTV) and investigate their potential to accurately determine the left ventricular volume at different dose levels from 50 to 500 mGy. The results were verified in phantom studies of a five-dimensional (5D) mathematical mouse phantom. Methods: Micro-CT data of eight mice, each administered with an x-ray dose of 500 mGy, were acquired, retrospectively gated for cardiac and respiratory motion and reconstructed using PCF, MKB, LDPC, and HDTV. Dose levels down to 50 mGy were simulated by using only a fraction of the projections. Contrast-to-noise ratio (CNR) was evaluated as a measure of image quality. Left ventricular volume was determined using different segmentation algorithms (Otsu, level sets, region growing). Forward projections of the 5D mouse phantom were performed to simulate a micro-CT scan. The simulated data were processed the same way as the real mouse data sets. Results: Compared to the conventional PCF reconstruction, the MKB, LDPC, and HDTV algorithm yield images of increased quality in terms of CNR. While the MKB reconstruction only provides small improvements, a significant increase of the CNR is observed in LDPC and HDTV reconstructions. The phantom studies demonstrate that left ventricular volumes can be determined accurately at 500 mGy. For lower dose levels which were simulated for real mouse data sets, the

  6. Critical Joints in Large Composite Primary Aircraft Structures. Volume 3: Ancillary Test Results

    Science.gov (United States)

    Bunin, Bruce L.; Sagui, R. L.

    1985-01-01

    A program was conducted to develop the technology for critical structural joints for composite wing structure that meets all the design requirements of a 1990 commercial transport aircraft. The results of a comprehensive ancillary test program are summarized, consisting of single-bolt composite joint specimens tested in a variety of configurations. These tests were conducted to characterize the strength and load deflection properties that are required for multirow joint analysis. The composite material was Toray 300 fiber and Ciba-Geigy 914 resin, in the form of 0.005 and 0.01 inch thick unidirectional tape. Tests were conducted in single and double shear for loaded and unloaded hole configurations under both tensile and compressive loading. Two different layup patterns were examined. All tests were conducted at room temperature. In addition, the results of NASA Standard Toughness Test (NASA RP 1092) are reported, which were conducted for several material systems.

  7. Critical joints in large composite primary aircraft structures. Volume 1: Technical summary

    Science.gov (United States)

    Bunin, Bruce L.

    1985-01-01

    A program was conducted at Douglas Aircraft Company to develop the technology for critical joints in composite wing structure that meets all the design requirements of a 1990 commercial transport aircraft. In fulfilling this objective, analytical procedures for joint design and analysis were developed during Phase 1 of the program. Tests were conducted at the element level to supply the empirical data required for methods development. Large composite multirow joints were tested to verify the selected design concepts and for correlation with analysis predictions. The Phase 2 program included additional tests to provide joint design and analysis data, and culminated with several technology demonstration tests of a major joint area representative of a commercial transport wing. The technology demonstration program of Phase 2 is discussed. The analysis methodology development, structural test program, and correlation between test results and analytical strength predictions are reviewed.

  8. Rectal Dose-Volume Histogram Parameters Are Associated With Long-Term Patient-Reported Gastrointestinal Quality of Life After Conventional and High-Dose Radiation for Prostate Cancer: A Subgroup Analysis of a Randomized Trial

    International Nuclear Information System (INIS)

    Nguyen, Paul L.; Chen, Ronald C.; Hoffman, Karen E.; Trofimov, Alexei; Efstathiou, Jason A.; Coen, John J.; Shipley, William U.; Zietman, Anthony L.; Talcott, James A.

    2010-01-01

    Purpose: We examined whether rectal dose-volume histogram (DVH) parameters were associated with long-term patient-reported gastrointestinal (GI) quality of life (QOL) after conventional (70.2 GyE) or high-dose (79.2 GyE) radiation for prostate cancer. Methods and Materials: Of 64 men with localized prostate cancer alive with a minimum 7-year follow-up after treatment as part of a randomized trial with either 70.2 GyE or 79.2 GyE of external beam radiation at Massachusetts General Hospital, 56 men (88%) returned a QOL questionnaire, and 50 of those men had DVH information. The DVH parameters of the anterior rectal wall were correlated with patient-reported long-term GI QOL using Pearson correlation and t tests. Results: There was a trend toward an association between increased long-term GI dysfunction and higher V60 (p = 0.07), V65 (p = 0.06), V70 (p = 0.09), and V75 (p = 0.09). When dichotomized by their medians, a V60 > 54% (p = 0.04), V70 > 44% (p = 0.06), and V75 > 39% (p = 0.06) were associated with increased long-term GI dysfunction. There was no difference in long-term GI dysfunction between men on the conventional vs. high-dose arms (p = 0.49). Conclusions: Dose-volume histogram parameters of the anterior rectal wall were associated with long-term patient-reported GI QOL after prostate radiation, whereas the dose prescribed to the prostate was not, suggesting that DVH constraints, rather than total prescribed dose, may have the greatest impact on long-term bowel dysfunction, and therefore that continued dose escalation may be feasible if appropriate dose-volume constraints are met.

  9. Dose-volume effects for pelvic bone marrow in predicting hematological toxicity in prostate cancer radiotherapy with pelvic node irradiation.

    Science.gov (United States)

    Sini, Carla; Fiorino, Claudio; Perna, Lucia; Noris Chiorda, Barbara; Deantoni, Chiara Lucrezia; Bianchi, Marco; Sacco, Vincenzo; Briganti, Alberto; Montorsi, Francesco; Calandrino, Riccardo; Di Muzio, Nadia; Cozzarini, Cesare

    2016-01-01

    To prospectively identify clinical/dosimetric predictors of acute/late hematologic toxicity (HT) in chemo-naÏve patients treated with whole-pelvis radiotherapy (WPRT) for prostate cancer. Data of 121 patients treated with adjuvant/salvage WPRT were analyzed (static-field IMRT n=19; VMAT/Rapidarc n=57; Tomotherapy n=45). Pelvic bone marrow (BM) was delineated as ilium (IL), lumbosacral, lower and whole pelvis (WP), and the relative DVHs were calculated. HT was graded both according to CTCAE v4.03 and as variation in percentage relative to baseline. Logistic regression was used to analyze association between HT and clinical/DVHs factors. Significant differences (p<0.005) in the DVH of BM volumes between different techniques were found: Tomotherapy was associated with larger volumes receiving low doses (3-20 Gy) and smaller receiving 40-50 Gy. Lower baseline absolute values of WBC, neutrophils and lymphocytes (ALC) predicted acute/late HT (p ⩽ 0.001). Higher BM V40 was associated with higher risk of acute Grade3 (OR=1.018) or late Grade2 lymphopenia (OR=1.005). Two models predicting lymphopenia were developed, both including baseline ALC, and BM WP-V40 (AUC=0.73) and IL-V40+smoking (AUC=0.904) for acute/late respectively. Specific regions of pelvic BM predicting acute/late lymphopenia, a risk factor for viral infections, were identified. The 2-variable models including specific constraints to BM may help reduce HT. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  10. Changing Therapeutic Paradigms: Predicting mCRC Lesion Response to Selective Internal Radionuclide Therapy (SIRT based on Critical Absorbed Dose Thresholds: A Case Study

    Directory of Open Access Journals (Sweden)

    Kathy W

    2017-01-01

    Full Text Available A 65 year old male with metastatic colorectal cancer (mCRC in the liver was referred for selective internal radionuclide therapy (SIRT following a history of extensive systemic chemotherapy. 90Y PET imaging was performed immediately after treatment and used to confirm lesion targeting and measure individual lesion absorbed doses. Lesion dosimetry was highly predictive of eventual response in the follow-up FDG PET performed 8 weeks after therapy. The derived radiation dose map was used to plan a second SIRT procedure aiming to protect healthy liver by keeping absorbed dose below the critical dose threshold, whilst targeting the remaining lesions that had received sub-critical dosing. Again, 90Y PET was performed immediately post-treatment and used to derive absorbed dose measures to both lesions and healthy parenchyma. Additional followup FDG PET imaging again confirmed the role of the 90Y PET dose map as an early predictor of response, and a tool for safe repeat treatment planning.

  11. Radioiodine therapy in Graves' disease based on tissue-absorbed dose calculations: effect of pre-treatment thyroid volume on clinical outcome

    Energy Technology Data Exchange (ETDEWEB)

    Reinhardt, Michael J.; Joe, Alexius Y.; Mallek, Dirk von; Ezziddin, Samer; Palmedo, Holger [Department of Nuclear Medicine, University Hospital of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany); Brink, Ingo [Department of Nuclear Medicine, University Hospital of Freiburg (Germany); Krause, Thomas M. [Department of Nuclear Medicine, Inselspital Bern (Switzerland)

    2002-09-01

    This study was performed with three aims. The first was to analyse the effectiveness of radioiodine therapy in Graves' disease patients with and without goitres under conditions of mild iodine deficiency using several tissue-absorbed doses. The second aim was to detect further parameters which might be predictive for treatment outcome. Finally, we wished to determine the deviation of the therapeutically achieved dose from that intended. Activities of 185-2,220 MBq radioiodine were calculated by means of Marinelli's formula to deliver doses of 150, 200 or 300 Gy to the thyroids of 224 patients with Graves' disease and goitres up to 130 ml in volume. Control of hyperthyroidism, change in thyroid volume and thyrotropin-receptor antibodies were evaluated 15{+-}9 months after treatment for each dose. The results were further evaluated with respect to pre-treatment parameters which might be predictive for therapy outcome. Thyroidal radioiodine uptake was measured every day during therapy to determine the therapeutically achieved target dose and its coefficient of variation. There was a significant dose dependency in therapeutic outcome: frequency of hypothyroidism increased from 27.4% after 150 Gy to 67.7% after 300 Gy, while the frequency of persistent hyperthyroidism decreased from 27.4% after 150 Gy to 8.1% after 300 Gy. Patients who became hypothyroid had a maximum thyroid volume of 42 ml and received a target dose of 256{+-}80 Gy. The coefficient of variation for the achieved target dose ranged between 27.7% for 150 Gy and 17.8% for 300 Gy. When analysing further factors which might influence therapeutic outcome, only pre-treatment thyroid volume showed a significant relationship to the result of treatment. It is concluded that a target dose of 250 Gy is essential to achieve hypothyroidism within 1 year after radioiodine therapy in Graves' disease patients with goitres up to 40 ml in volume. Patients with larger goitres might need higher doses

  12. Sensitivity of volumetric modulated arc therapy patient specific QA results to multileaf collimator errors and correlation to dose volume histogram based metrics.

    LENUS (Irish Health Repository)

    Coleman, Linda

    2013-11-01

    This study investigates the impact of systematic multileaf collimator (MLC) positional errors on gamma analysis results used for quality assurance (QA) of Rapidarc treatments. In addition, this study evaluates the relationship of these gamma analysis results and clinical dose volume histogram metrics (DVH) for Rapidarc treatment plans.

  13. Progressive striatal and hippocampal volume loss in initially antipsychotic-naive, first-episode schizophrenia patients treated with quetiapine: relationship to dose and symptoms

    DEFF Research Database (Denmark)

    Ebdrup, Bjørn H; Skimminge, Arnold; Rasmussen, Hans

    2011-01-01

    -weighted images (3 T) from 22 patients and 28 matched healthy controls were analysed using tensor-based morphometry. Non-parametric voxel-wise group comparisons were performed. Small volume correction was employed for striatum, hippocampus and ventricles. Dose-dependent medication effects and associations...

  14. Report on Intact and Degraded Criticality for Selected Plutonium Waste Forms in a Geologic Repository, Volume I: MOX SNF

    Energy Technology Data Exchange (ETDEWEB)

    J.A. McClure

    1998-09-21

    As part of the plutonium waste form development and down-select process, repository analyses have been conducted to evaluate the long-term performance of these forms for repository acceptance. Intact and degraded mode criticality analysis of the mixed oxide (MOX) spent fuel is presented in Volume I, while Volume II presents the evaluations of the waste form containing plutonium immobilized in a ceramic matrix. Although the ceramic immobilization development program is ongoing, and refinements are still being developed and evaluated, this analysis provides value through quick feed-back to this development process, and as preparation for the analysis that will be conducted starting in fiscal year (FY) 1999 in support of the License Application. While no MOX fuel has been generated in the United States using weapons-usable plutonium, Oak Ridge National Laboratory (ORNL) has conducted calculations on Westinghouse-type reactors to determine the expected characteristics of such a fuel. These spent nuclear fuel (SNF) characteristics have been used to determine the long-term potential for criticality in a repository environment. In all instances the methodology and scenarios used in these analyses are compatible with those developed and used for Commercial Spent Nuclear Fuel (CSNF) and Defense High Level Waste (DHLW), as tailored for the particular characteristics of the waste forms. This provides a common basis for comparison of the results. This analysis utilizes dissolution, solubility, and thermodynamic data that are currently available. Additional data on long-term behavior is being developed, and later analyses (FY 99) to support the License Application will use the very latest information that has been generated. Ranges of parameter values are considered to reflect sensitivity to uncertainty. Most of the analysis is focused on those parameter values that produce the worst case results, so that potential licensing issues can be identified.

  15. SU-F-T-206: Proton Treatment Techniques for Posterior Fossa Tumors: Consequences for LET and Dose/Volume Parameters for the Brainstem and Organs at Risk

    Energy Technology Data Exchange (ETDEWEB)

    Giantsoudi, D; Adams, J; MacDonald, S; Paganetti, H [Massachusetts General Hospital, Boston, MA (United States)

    2016-06-15

    Purpose: In proton radiation therapy of posterior fossa tumors, to spare other sensitive structures, the preferred beam geometry results in placing the treatment field distal edge within or just beyond the brainstem, including in at least partially in the treatment volume. Concerns for brainstem toxicity are increased and a controversy exists as to weather the beam’s distal edge should be placed within the brainstem or beyond it, to avoid elevated linear energy transfer (LET) and relative biological effectiveness (RBE) within the brainstem. The dosimetric efficacy of these techniques was examined, accounting for LET- and dose-dependent variable RBE distributions. Methods: Three treatment planning techniques were applied in six ependymoma cases: (a) three-field dose-sparing, with beams’ distal edge within the brainstem; (b) three-field LET-sparing, using same beam directions as (a) but extended field ranges beyond the brainstem; (c) two-posterior-oblique LET-sparing, with extended ranges as (b). Monte Carlo calculated dose, LET and RBE-weighted dose distributions were compared. Results: Lower LET values in the brainstem were accompanied by higher median dose: 53.7 Gy[RBE] and 54.3 Gy[RBE] for techniques (b) and (c) versus 52.1 Gy[RBE] for (a). Accounting for variable RBE, a 15% increase of the brainstem volume receiving at least 60 Gy[RBE] was observed for technique (c) versus (a). Maximum variable-RBE-weighted brainstem dose was comparable for all techniques. Conclusion: Extending the treatment beam range beyond the brainstem, significantly increased its volume receiving high dose radiation, even when accounting for the decreased LET values. The dosimetric benefits of techniques limiting the brainstem dose may outweigh the impact of LET reduction achieved through this technique, especially since clinical consequences of increased LET at the end of range have not been proven yet.

  16. Estimation of dose in dental radiology exams in critical regions; Estimativa de dose em exames de radiologia odontologica em regioes criticas

    Energy Technology Data Exchange (ETDEWEB)

    Bonzoumet, S.P.J.; Braz, D. [Coordenacao dos Programas de Pos-Graduacao de Engenharia (LIN/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear. Lab. de Instrumentacao Nuclear; Barroso, R.C. [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Inst. de Fisica; Mauricio, Claudia; Domingues, Claudio [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Padilha, Lucas, E-mail: sielso@lin.ufrj.br [Universidade Federal do Rio de Janeiro (HUCFF/UFRJ), RJ (Brazil). Hospital Universitario Clementino Fraga Filho

    2005-07-01

    The objective of this paper is to estimate the values of doses, which are absorbed dose to the lens and thyroid in a dental X-ray. Thermoluminescence dosimeters were used, once they provide a reading of quality and effectiveness. This study was based on dental exams conducted in patients in order to estimate the dose that disperses to the lens of the eye and for the thyroid during an intraoral exam. Data collection took place in two institutions, one governmental, which had the device SELETRONIC 70X and other particular. This study showed that there is a considerable variation between the appliances. Using the appliance DABI 1070, there was a greater absorption of radiation in the right eye (values greater than 5 mGy) and a lower dose in the thyroid, and the Seletronic 70X presented an incidence of higher dose deposited in the skin and in other points there was a balance in the values. In the appliance SELETRONIC 70X, there was again a greater absorption of radiation in the right eye and a lower setting in the thyroid. The excessive dose, besides does not favor at all for the quality of radiograph, represents a risk for the patient who absorbs unnecessary and harmful radiation to the body.

  17. Heart and coronary artery protection in patients with mediastinal Hodgkin lymphoma treated with intensity-modulated radiotherapy: Dose constraints to virtual volumes or to organs at risk?

    International Nuclear Information System (INIS)

    Ghalibafian, Mithra; Beaudre, Anne; Girinsky, Theodore

    2008-01-01

    Background and purpose: To increase heart and coronary artery protection in patients with mediastinal Hodgkin lymphoma treated with intensity-modulated radiotherapy (IMRT). Materials and methods: Twenty patients with early-stage mediastinal Hodgkin lymphoma entered the study. IMRT was delivered to the initially involved lymph node volumes. Various virtual volumes (VVs) were designed to improve the protection of the heart and the origin of the coronary arteries, which were the organs at risk (OARs), while preserving adequate PTV coverage. The results obtained with VVs were then compared with those obtained with dose constraints assigned to OARs. Results: The most satisfactory VV was obtained using the PTV expansion concept. The best compromise between adequate PTV coverage and OAR protection was obtained with dose constraints assigned to the PTV expansion VV and to the origin of the coronary arteries. Conclusions: IMRT can be improved by using dose constraints assigned to the PTV expansion VV and/or to the origin of the coronary arteries

  18. Volume and dose rate dependent (MDR-LDR Ir-192 afterloading interstitial brachytherapy) treatment optimisation, for squamouscell carcinoma of the lip

    International Nuclear Information System (INIS)

    Stas, Nathalie; Goncalves, Julieta; Pinho, Eliana; Trigo, Lurdes; Fernandes, Tome; Vieira, Elio

    1996-01-01

    Introduction: From 1/1/90 to 1/1/95, 53 patients with squamouscell carcinoma of the lip were treated by MDR or LDR Ir-192 afterloading interstitital brachytherapy. We compare the oncological and aesthetical results and sequelae depending on the volume and the dose rate. Material and methods: 53 patients, 41 men and 12 women, median age = 66y; 48 primary tumors (T1 = 26; T2 = 16; T3 = 6; N0 = 47; N1 = 1; M0 = 48) and 5 recurrencies; squamouscell carcinoma (grade 1 =45, g2 =6, g3 =2); clinical extension: buccal comissure=3, check =2, muscular =15, skin =7, lower and upper lip =1. Before radiotherapy, 28 biopsies and 25 excisional surgeries (19 with positive margins, 6 with negative margins) were performed. Brachytherapy was performed alone (dose 60-75 Gy BD85%) or as a boost (dose 10-30 Gy BD85%) associated with external beam (dose 46-50 Gy). MDR or LDR microselectron's afterloading was done after a computerised dosimetry (Paris System): treatment mean time = 30, 98 hours; mean volume = 10,2 cc (T1-T2 8, 61cc); Ir - 192 activity = range 0,7 - 4,792 mCi/cm; reference dose rate 45,6 - 290, 1 cGy/h. Results: 46 patients are alive without cancer, 1 died without responding, 6 died from non oncological diseases; 8 patients had recurrences (5 local, 3 nodal) but are alive. Mean follow-up 30,83 months (range 3-60m), mean DFS = 22,49 m (range 5-57m). Acute secondary effects: 30 radioepithelyties (grade 1 = 7, g2=23, g3=14), and 39 radiomucitis (g1=3; g2=23; g3=13); mean time for complete healing = 21, 66 days. Sequelae: moderate sclerosis of the skin =11, skin retraction = 1, hyperpigmentation2, depigmentation= 10, edema= 6, gingivitis= 7. Aesthetical results: good32; moderate= 18; bad= 2, very bad= 1 (uncontrolled tumor). Conclusions: The sequelae and aesthetical results are closely dependent on the treated volume and the dose rate, less dependent on the total dose, and independent on the Iridium activity. Complete healing time does not influence the late aesthetical results

  19. Effects of substitution and high-dose thyroid hormone therapy on deiodination, sulfoconjugation, and tissue thyroid hormone levels in prolonged critically ill rabbits

    NARCIS (Netherlands)

    Y. Debaveye (Yves); B. Ellger (Björn); L. Mebis (Liese); T.J. Visser (Theo); V.M. Darras (Veerle); G. van den Berghe (Greet)

    2008-01-01

    textabstractTo delineate the metabolic fate of thyroid hormone in prolonged critically ill rabbits, we investigated the impact of two dose regimes of thyroid hormone on plasma 3,3′-diiodothyronine (T2) and T4S, deiodinase type 1 (D1) and D3 activity, and tissue iodothyronine levels in liver and

  20. Influencia do período de coleta sobre o volume, motilidade e doses de sêmen em suínos Influence of the collection period on volume, motility and semen doses in swine

    Directory of Open Access Journals (Sweden)

    Martha Lopes Schuch de Castro

    1996-12-01

    Full Text Available O presente trabalho teve como objetivo determinar ainfluência do ano e mês de coleta sobre o volume (VOL, motilidade (MOT e doses de sêmen produzidas (DO, as correlações existentes entre as variáveis e as suas repetibilidades. Foram analisadas amostras de sêmen de 96 machos pertencentes as raças Landrace (41, Large White (31 e Duroc (24, durante o período (1981 a 1987 de permanência dos mesmos na Central de Inseminação Artificial de Suínos de Estrela - RS. O número de amostras dês sêmen coletadas foi de 7.264 da raça Landrace, 3.589 da raça Large White e 3.051 da raça Duroc. Os resultados mostraram haver influência (PThe aim of this experiment was to determine the influence of the collection period on volume (VOL, motility (MOT and semen doses (DO, and the correlation among the six variables and their repeatibilities. Semen samples from ninety (96 boars belonging to Landrace (41, Large White (31 and Duroc (24 breeds were analyzed, taken into account the permanence period (1981 to 1987 of the boars at the Artificial Insemination Center -Estrela - RS. The number of semen samples collected were: Landrace 7,264, Large White 3,589 and Duroc, 3,051. Year and month of collection had influence (P<0.01 on the variables analyzed. Minimum and maximum average values, within each breed, were VOL 236.9 and 300.4ml (Landrace, 238.1 and 284.1ml (Large White and 150.0 and 201.1ml (Duroc: MOT 79.2 and 80.3% (Landrace, 76.7 and 78.0% (Large White and 77.8 and 79.1% (Duroc; DO 12.0 and 14.7 (Landrace, 10.1 and 13.0 (Large White and 9.1 and 11.9 (Duroc, respectively. Correlations between VOL and DO were 0.30 (Landrace, 0.36 (Large White and 0.36 (Duroc. Correlations between VOL and MOT were close to zero (Landrace -0.05, Large White 0.03 and Duroc 0.01, and between MOT and DO were 0.08 (Landrace, 0.15 (Large White and 0.13 (Duroc. Repeatibilities were VOL 0.49 (Landrace, 0.59 (Large White and 0.54 (Duroc; MOT 0.18 (Landrace, 0.27 (Large White and

  1. CT Pulmonary Angiography at Reduced Radiation Exposure and Contrast Material Volume Using Iterative Model Reconstruction and iDose4 Technique in Comparison to FBP.

    Science.gov (United States)

    Laqmani, Azien; Kurfürst, Maximillian; Butscheidt, Sebastian; Sehner, Susanne; Schmidt-Holtz, Jakob; Behzadi, Cyrus; Nagel, Hans Dieter; Adam, Gerhard; Regier, Marc

    2016-01-01

    To assess image quality of CT pulmonary angiography (CTPA) at reduced radiation exposure (RD-CTPA) and contrast medium (CM) volume using two different iterative reconstruction (IR) algorithms (iDose4 and iterative model reconstruction (IMR)) in comparison to filtered back projection (FBP). 52 patients (body weight < 100 kg, mean BMI: 23.9) with suspected pulmonary embolism (PE) underwent RD-CTPA (tube voltage: 80 kV; mean CTDIvol: 1.9 mGy) using 40 ml CM. Data were reconstructed using FBP and two different IR algorithms (iDose4 and IMR). Subjective and objective image quality and conspicuity of PE were assessed in central, segmental, and subsegmental arteries. Noise reduction of 55% was achieved with iDose4 and of 85% with IMR compared to FBP. Contrast-to-noise ratio significantly increased with iDose4 and IMR compared to FBP (p<0.05). Subjective image quality was rated significantly higher at IMR reconstructions in comparison to iDose4 and FBP. Conspicuity of central and segmental PE significantly improved with the use of IMR. In subsegmental arteries, iDose4 was superior to IMR. CTPA at reduced radiation exposure and contrast medium volume is feasible with the use of IMR, which provides improved image quality and conspicuity of pulmonary embolism in central and segmental arteries.

  2. CT Pulmonary Angiography at Reduced Radiation Exposure and Contrast Material Volume Using Iterative Model Reconstruction and iDose4 Technique in Comparison to FBP.

    Directory of Open Access Journals (Sweden)

    Azien Laqmani

    Full Text Available To assess image quality of CT pulmonary angiography (CTPA at reduced radiation exposure (RD-CTPA and contrast medium (CM volume using two different iterative reconstruction (IR algorithms (iDose4 and iterative model reconstruction (IMR in comparison to filtered back projection (FBP.52 patients (body weight < 100 kg, mean BMI: 23.9 with suspected pulmonary embolism (PE underwent RD-CTPA (tube voltage: 80 kV; mean CTDIvol: 1.9 mGy using 40 ml CM. Data were reconstructed using FBP and two different IR algorithms (iDose4 and IMR. Subjective and objective image quality and conspicuity of PE were assessed in central, segmental, and subsegmental arteries.Noise reduction of 55% was achieved with iDose4 and of 85% with IMR compared to FBP. Contrast-to-noise ratio significantly increased with iDose4 and IMR compared to FBP (p<0.05. Subjective image quality was rated significantly higher at IMR reconstructions in comparison to iDose4 and FBP. Conspicuity of central and segmental PE significantly improved with the use of IMR. In subsegmental arteries, iDose4 was superior to IMR.CTPA at reduced radiation exposure and contrast medium volume is feasible with the use of IMR, which provides improved image quality and conspicuity of pulmonary embolism in central and segmental arteries.

  3. Genitourinary Toxicity After High-Dose-Rate (HDR) Brachytherapy Combined With Hypofractionated External Beam Radiotherapy for Localized Prostate Cancer: An Analysis to Determine the Correlation Between Dose-Volume Histogram Parameters in HDR Brachytherapy and Severity of Toxicity

    International Nuclear Information System (INIS)

    Ishiyama, Hiromichi; Kitano, Masashi; Satoh, Takefumi; Kotani, Shouko; Uemae, Mineko; Matsumoto, Kazumasa; Okusa, Hiroshi; Tabata, Ken-ichi; Baba, Shiro; Hayakawa, Kazushige

    2009-01-01

    Purpose: To evaluate the severity of genitourinary (GU) toxicity in high-dose-rate (HDR) brachytherapy combined with hypofractionated external beam radiotherapy (EBRT) for prostate cancer and to explore factors that might affect the severity of GU toxicity. Methods and Materials: A total of 100 Japanese men with prostate cancer underwent 192 Ir HDR brachytherapy combined with hypofractionated EBRT. Mean (SD) dose to 90% of the planning target volume was 6.3 (0.7) Gy per fraction of HDR. After 5 fractions of HDR treatment, EBRT with 10 fractions of 3 Gy was administrated. The urethral volume receiving 1-15 Gy per fraction in HDR brachytherapy (V1-V15) and the dose to at least 5-100% of urethral volume in HDR brachytherapy (D5-D100) were compared between patients with Grade 3 toxicity and those with Grade 0-2 toxicity. Prostate volume, patient age, and International Prostate Symptom Score were also compared between the two groups. Results: Of the 100 patients, 6 displayed Grade 3 acute GU toxicity, and 12 displayed Grade 3 late GU toxicity. Regarding acute GU toxicity, values of V1, V2, V3, and V4 were significantly higher in patients with Grade 3 toxicity than in those with Grade 0-2 toxicity. Regarding late GU toxicity, values of D70, D80, V12, and V13 were significantly higher in patients with Grade 3 toxicity than in those with Grade 0-2 toxicity. Conclusions: The severity of GU toxicity in HDR brachytherapy combined with hypofractionated EBRT for prostate cancer was relatively high. The volume of prostatic urethra was associated with grade of acute GU toxicity, and urethral dose was associated with grade of late GU toxicity.

  4. Critical reevaluation of the dose-response relationships for carcinogenic effects of low-level ionizing radiation

    International Nuclear Information System (INIS)

    Upton, A.C.

    2003-01-01

    In recent decades, it has been customary, for radiation protection purposes, to assume that the overall risk of radiation-induced cancer increases as a linear-nonthreshold function of the dose. The existing data do not exclude the existence of a threshold, however, and the dose-response relationship is known to vary, depending on the type of cancer in queation, the dose, dose rate, and LET of the radiation, the age, sex, and physiological state of the exposed individuals, and other variables, including the potential influence of adaptive responses and bystander effects at low doses. In light of advncing knowledge, therefore, the dose-response relationship for carcinogenic effects of low-level radiation has been reevaluated periodically by the National Council on Radiation Protection and Measurements, the International Commission of Radiological Protection, the United Nations Scientific Committee on the Effects of Atomic Radiation, the U.S. National Academy of Sciences, and other organizations. The most recent such reviews have generally found the weight of evidence to suggest that lesions which are precursors to cancer (i.e., mutations and chromosome aberrations), and certain types of cancer as well, may increase in frequency linearly with the dose in the low-dose domain. On this basis, it is concluded that no alternative dose-response model for the carcinogenic effects of low-level radiation is more plausible than the linear-nonthreshold model, although other dose-response relationships cannot be excluded. (authors)

  5. Dose-Volume Relationships for Acute Bowel Toxicity in Patients Treated With Pelvic Nodal Irradiation for Prostate Cancer

    International Nuclear Information System (INIS)

    Fiorino, Claudio; Alongi, Filippo; Perna, Lucia; Broggi, Sara; Cattaneo, Giovanni Mauro; Cozzarini, Cesare; Di Muzio, Nadia; Fazio, Ferruccio; Calandrino, Riccardo

    2009-01-01

    Purpose: To find correlation between dose-volume histograms (DVHs) of the intestinal cavity (IC) and moderate-severe acute bowel toxicity in men with prostate cancer treated with pelvic nodal irradiation. Methods and Materials: The study group consisted of 191 patients with localized prostate cancer who underwent whole-pelvis radiotherapy with radical or adjuvant/salvage intent during January 2004 to November 2007. Complete planning/clinical data were available in 175 of these men, 91 of whom were treated with a conventional four-field technique (50.4 Gy, 1.8 Gy/fraction) and 84 of whom were treated with IMRT using conventional Linac (n = 26, 50.4 Gy, 1.8 Gy/fraction) or Helical TomoTherapy (n = 58, 50-54 Gy, 1.8-2 Gy/fraction). The IC outside the planning target volume (PTV) was contoured and the DVH for the first 6 weeks of treatment was recovered in all patients. The correlation between a number of clinical and DVH (V10-V55) variables and toxicity was investigated in univariate and multivariate analyses. The correlation between DVHs for the IC outside the PTV and DVHs for the whole IC was also assessed. Results: Twenty-two patients experienced toxicity (3/22 in the IMRT/tomotherapy group). Univariate analyses showed a significant correlation between V20-V50 and toxicity (p = 0.0002-0.001), with a higher predictive value observed for V40-V50. Previous prostatectomy (p = 0.066) and abdominal/pelvic surgery (p = 0.12) also correlated with toxicity. Multivariate analysis that included V45, abdominal/pelvic surgery, and prostatectomy showed that the most predictive parameters were V45 (p = 0.002) and abdominal/pelvic surgery (p = 0.05, HR = 2.4) Conclusions: Our avoidance IMRT approach drastically reduces the incidence of acute bowel toxicity. V40-V50 of IC and, secondarily, previous abdominal/pelvic surgery were the main predictors of acute bowel toxicity.

  6. Development of posture-specific computational phantoms using motion capture technology and application to radiation dose-reconstruction for the 1999 Tokai-Mura nuclear criticality accident

    International Nuclear Information System (INIS)

    Vazquez, Justin A; Caracappa, Peter F; Xu, X George

    2014-01-01

    The majority of existing computational phantoms are designed to represent workers in typical standing anatomical postures with fixed arm and leg positions. However, workers found in accident-related scenarios often assume varied postures. This paper describes the development and application of two phantoms with adjusted postures specified by data acquired from a motion capture system to simulate unique human postures found in a 1999 criticality accident that took place at a JCO facility in Tokai-Mura, Japan. In the course of this accident, two workers were fatally exposed to extremely high levels of radiation. Implementation of the emergent techniques discussed produced more accurate and more detailed dose estimates for the two workers than were reported in previous studies. A total-body dose of 6.43 and 26.38 Gy was estimated for the two workers, who assumed a crouching and a standing posture, respectively. Additionally, organ-specific dose estimates were determined, including a 7.93 Gy dose to the thyroid and 6.11 Gy dose to the stomach for the crouching worker and a 41.71 Gy dose to the liver and a 37.26 Gy dose to the stomach for the standing worker. Implications for the medical prognosis of the workers are discussed, and the results of this study were found to correlate better with the patient outcome than previous estimates, suggesting potential future applications of such methods for improved epidemiological studies involving next-generation computational phantom tools. (paper)

  7. Development of posture-specific computational phantoms using motion capture technology and application to radiation dose-reconstruction for the 1999 Tokai-Mura nuclear criticality accident

    Science.gov (United States)

    Vazquez, Justin A.; Caracappa, Peter F.; Xu, X. George

    2014-09-01

    The majority of existing computational phantoms are designed to represent workers in typical standing anatomical postures with fixed arm and leg positions. However, workers found in accident-related scenarios often assume varied postures. This paper describes the development and application of two phantoms with adjusted postures specified by data acquired from a motion capture system to simulate unique human postures found in a 1999 criticality accident that took place at a JCO facility in Tokai-Mura, Japan. In the course of this accident, two workers were fatally exposed to extremely high levels of radiation. Implementation of the emergent techniques discussed produced more accurate and more detailed dose estimates for the two workers than were reported in previous studies. A total-body dose of 6.43 and 26.38 Gy was estimated for the two workers, who assumed a crouching and a standing posture, respectively. Additionally, organ-specific dose estimates were determined, including a 7.93 Gy dose to the thyroid and 6.11 Gy dose to the stomach for the crouching worker and a 41.71 Gy dose to the liver and a 37.26 Gy dose to the stomach for the standing worker. Implications for the medical prognosis of the workers are discussed, and the results of this study were found to correlate better with the patient outcome than previous estimates, suggesting potential future applications of such methods for improved epidemiological studies involving next-generation computational phantom tools.

  8. Rectal Bleeding After High-Dose-Rate Brachytherapy Combined With Hypofractionated External-Beam Radiotherapy for Localized Prostate Cancer: The Relationship Between Dose-Volume Histogram Parameters and the Occurrence Rate

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Masahiko, E-mail: masaoka@showa.gunma-u.ac.jp [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Gunma (Japan); Ishikawa, Hitoshi; Ebara, Takeshi; Kato, Hiroyuki; Tamaki, Tomoaki [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Gunma (Japan); Akimoto, Tetsuo [Department of Radiation Oncology, Tokyo Women' s Medical University, Tokyo (Japan); Ito, Kazuto; Miyakubo, Mai; Yamamoto, Takumi; Suzuki, Kazuhiro [Department of Urology, Gunma University Graduate School of Medicine, Gunma (Japan); Takahashi, Takeo; Nakano, Takashi [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Gunma (Japan)

    2012-02-01

    Purpose: To determine the predictive risk factors for Grade 2 or worse rectal bleeding after high-dose-rate brachytherapy (HDR-BT) combined with hypofractionated external-beam radiotherapy (EBRT) for prostate cancer using dose-volume histogram analysis. Methods and Materials: The records of 216 patients treated with HDR-BT combined with EBRT were analyzed. The treatment protocols for HDR-BT were 5 Gy Multiplication-Sign five times in 3 days or 7 Gy Multiplication-Sign three, 10.5 Gy Multiplication-Sign two, or 9 Gy Multiplication-Sign two in 2 days. The EBRT doses ranged from 45 to 51 Gy with a fractional dose of 3 Gy. Results: In 20 patients Grade 2 or worse rectal bleeding developed, and the cumulative incidence rate was 9% at 5 years. By converting the HDR-BT and EBRT radiation doses into biologic effective doses (BED), the BED{sub 3} at rectal volumes of 5% and 10% in the patients who experienced bleeding were significantly higher than those in the remaining 196 patients. Univariate analysis showed that a higher rectal BED{sub 3-5%} and the use of fewer needles in brachytherapy were correlated with the incidence of bleeding, but BED{sub 3-5%} was found to be the only significant factor on multivariate analysis. Conclusions: The radiation dose delivered to small rectal lesions as 5% is important for predicting Grade 2 or worse rectal bleeding after HDR-BT combined with EBRT for prostate cancer.

  9. Surgeon, not institution, case volume is associated with limb outcomes after lower extremity bypass for critical limb ischemia in the Vascular Quality Initiative.

    Science.gov (United States)

    Johnston, Lily E; Tracci, Margaret C; Kern, John A; Cherry, Kenneth J; Kron, Irving L; Upchurch, Gilbert R; Robinson, William P

    2017-11-01

    Studies from large administrative databases have demonstrated associations between institutional case volume and outcomes after lower extremity bypass (LEB). We hypothesized that increased institutional and surgeon volume would be associated with improved outcomes after LEB. Using a national, prospectively collected clinical database, the objective of this study was to determine the effects of both surgeon and institutional volume on outcomes after LEB. The Vascular Quality Initiative (VQI) was queried to identify all LEBs for critical limb ischemia or claudication between 2004 and 2014. Average annual case volume was calculated by dividing an institution's or surgeon's total LEB volume by the number of years they reported to the VQI. Institutional and surgeon volumes were analyzed as continuous variables to determine the impact of volume on major adverse cardiac events (MACEs), major adverse limb events (MALEs), graft patency, and amputation-free survival. Hierarchical regression models were used with cases clustered by surgeon and center. Time-dependent outcomes were evaluated with multivariable shared frailty Cox proportional hazards models. From 2004 to 2014, there were 14,678 LEB operations performed at 114 institutions by 587 surgeons. Average annual institutional volume ranged from 1.0 to 137.5 LEBs per year, with a median of 26.9 (interquartile range, 14-45.3). Average annual surgeon volume ranged from 1 to 52 LEBs per year with a median of 5.7 (interquartile range, 2.5-9.3). Institutional LEB volume was not associated with MACEs or MALEs or with loss of patency. However, average annual surgeon volume was independently associated with reduced MALEs and improved primary patency. Institutional and surgeon volume did not predict MACEs. In contradistinction to previous studies, there was no relationship in this study between institutional LEB volume and outcomes after LEB. However, greater average annual surgeon volume was associated with improved primary

  10. Safety analysis for the Abadia de Goias repository: alternative evaluation of the ingestion dose rate critical distance; Analise de seguranca para o repositorio de Abadia de Goias: avaliacao alternativa da distancia critica de taxa de dose de ingestao

    Energy Technology Data Exchange (ETDEWEB)

    Martin Alves, A.S. de; Passos, E.M. dos [NUCLEN, Rio de Janeiro, RJ (Brazil)

    1995-12-31

    An alternative calculation of the ingestion dose rate critical distance due to a hypothetical release of Cs-137 from the structure of the Repository of Abadia de Goias is presented. The release pathway considers the repository - groundwater region - well - and food chain. The main adopted modification comparing to the previous work is the inclusion of the convective and molecular diffusion terms in the radionuclide transport equation in addition to the radioactive decay term. (author). 6 refs, 1 tab.

  11. Influence of 320-detector-row volume scanning and AAPM report 111 CT dosimetry metrics on size-specific dose estimate: a Monte Carlo study.

    Science.gov (United States)

    Haba, Tomonobu; Koyama, Shuji; Kinomura, Yutaka; Ida, Yoshihiro; Kobayashi, Masanao

    2016-09-01

    The American Association of Physicists in Medicine (AAPM) task group 204 has recommended the use of size-dependent conversion factors to calculate size-specific dose estimate (SSDE) values from volume computed tomography dose index (CTDIvol) values. However, these conversion factors do not consider the effects of 320-detector-row volume computed tomography (CT) examinations or the new CT dosimetry metrics proposed by AAPM task group 111. This study aims to investigate the influence of these examinations and metrics on the conversion factors reported by AAPM task group 204, using Monte Carlo simulations. Simulations were performed modelling a Toshiba Aquilion ONE CT scanner, in order to compute dose values in water for cylindrical phantoms with 8-40-cm diameters at 2-cm intervals for each scanning parameter (tube voltage, bow-tie filter, longitudinal beam width). Then, the conversion factors were obtained by applying exponential regression analysis between the dose values for a given phantom diameter and the phantom diameter combined with various scanning parameters. The conversion factors for each scanning method (helical, axial, or volume scanning) and CT dosimetry method (i.e., the CTDI100 method or the AAPM task group 111 method) were in agreement with those reported by AAPM task group 204, within a percentage error of 14.2 % for phantom diameters ≥11.2 cm. The results obtained in this study indicate that the conversion factors previously presented by AAPM task group 204 can be used to provide appropriate SSDE values for 320-detector-row volume CT examinations and the CT dosimetry metrics proposed by the AAPM task group 111.

  12. Impact of intra-arterial administration of boron compounds on dose-volume histograms in boron neutron capture therapy for recurrent head-and-neck tumors

    International Nuclear Information System (INIS)

    Suzuki, Minoru; Sakurai, Yoshinori; Nagata, Kenji; Kinashi, Yuko; Masunaga, Shinichiro; Ono, Koji; Maruhashi, Akira; Kato, Ituro; Fuwa, Nobukazu; Hiratsuka, Junichi; Imahori, Yoshio

    2006-01-01

    Purpose: To analyze the dose-volume histogram (DVH) of head-and-neck tumors treated with boron neutron capture therapy (BNCT) and to determine the advantage of the intra-arterial (IA) route over the intravenous (IV) route as a drug delivery system for BNCT. Methods and Materials: Fifteen BNCTs for 12 patients with recurrent head-and-neck tumors were included in the present study. Eight irradiations were done after IV administration of boronophenylalanine and seven after IA administration. The maximal, mean, and minimal doses given to the gross tumor volume were assessed using a BNCT planning system. Results: The results are reported as median values with the interquartile range. In the IA group, the maximal, mean, and minimal dose given to the gross tumor volume was 68.7 Gy-Eq (range, 38.8-79.9), 45.0 Gy-Eq (range, 25.1-51.0), and 13.8 Gy-Eq (range, 4.8-25.3), respectively. In the IV group, the maximal, mean, and minimal dose given to the gross tumor volume was 24.2 Gy-Eq (range, 21.5-29.9), 16.4 Gy-Eq (range, 14.5-20.2), and 7.8 Gy-Eq (range, 6.8-9.5), respectively. Within 1-3 months after BNCT, the responses were assessed. Of the 6 patients in the IV group, 2 had a partial response, 3 no change, and 1 had progressive disease. Of 4 patients in the IA group, 1 achieved a complete response and 3 a partial response. Conclusion: Intra-arterial administration of boronophenylalanine is a promising drug delivery system for head-and-neck BNCT

  13. Effects of critical coronary stenosis on global systolic left ventricular function quantified by pressure-volume relations during dobutamine stress in the canine heart

    NARCIS (Netherlands)

    Steendijk, P.; Baan, J.; van der Velde, E. T.

    1998-01-01

    In this study we quantified the effects of a critical coronary stenosis on global systolic function using pressure-volume relations at baseline and during incremental dobutamine stress. The effects of coronary stenosis have previously been analyzed mainly in terms of regional (dys)function. Global

  14. Role of renal function in risk assessment of target non-attainment after standard dosing of meropenem in critically ill patients: a prospective observational study.

    Science.gov (United States)

    Ehmann, Lisa; Zoller, Michael; Minichmayr, Iris K; Scharf, Christina; Maier, Barbara; Schmitt, Maximilian V; Hartung, Niklas; Huisinga, Wilhelm; Vogeser, Michael; Frey, Lorenz; Zander, Johannes; Kloft, Charlotte

    2017-10-21

    Severe bacterial infections remain a major challenge in intensive care units because of their high prevalence and mortality. Adequate antibiotic exposure has been associated with clinical success in critically ill patients. The objective of this study was to investigate the target attainment of standard meropenem dosing in a heterogeneous critically ill population, to quantify the impact of the full renal function spectrum on meropenem exposure and target attainment, and ultimately to translate the findings into a tool for practical application. A prospective observational single-centre study was performed with critically ill patients with severe infections receiving standard dosing of meropenem. Serial blood samples were drawn over 4 study days to determine meropenem serum concentrations. Renal function was assessed by creatinine clearance according to the Cockcroft and Gault equation (CLCR CG ). Variability in meropenem serum concentrations was quantified at the middle and end of each monitored dosing interval. The attainment of two pharmacokinetic/pharmacodynamic targets (100%T >MIC , 50%T >4×MIC ) was evaluated for minimum inhibitory concentration (MIC) values of 2 mg/L and 8 mg/L and standard meropenem dosing (1000 mg, 30-minute infusion, every 8 h). Furthermore, we assessed the impact of CLCR CG on meropenem concentrations and target attainment and developed a tool for risk assessment of target non-attainment. Large inter- and intra-patient variability in meropenem concentrations was observed in the critically ill population (n = 48). Attainment of the target 100%T >MIC was merely 48.4% and 20.6%, given MIC values of 2 mg/L and 8 mg/L, respectively, and similar for the target 50%T >4×MIC . A hyperbolic relationship between CLCR CG (25-255 ml/minute) and meropenem serum concentrations at the end of the dosing interval (C 8h ) was derived. For infections with pathogens of MIC 2 mg/L, mild renal impairment up to augmented renal function was

  15. Changes in lateral dimensions of irradiated volume and their impact on the accuracy of dose delivery during radiotherapy for head and neck cancer

    International Nuclear Information System (INIS)

    Senkus-Konefka, Elzbieta; Naczk, Edmund; Borowska, Ilona; Badzio, Andrzej; Jassem, Jacek

    2006-01-01

    Background and purpose: To assess changes in lateral dimensions of irradiated volume during head and neck cancer radiotherapy and to determine their impact on the accuracy of dose delivery. Patients and methods: Lateral dimensions of irradiated volumes were measured in five predefined points prior to treatment and then bi-weekly. For each measurement, midline dose was calculated and verified using in vivo dosimetry. Early radiation reactions, patient weight changes and the need to modify radiotherapy accessories were also recorded. The study included 33 head and neck cancer patients irradiated using parallel opposed megavoltage fields. Results: Body mass changes during radiotherapy ranged from -18 to +4 kg (median -5). Lateral dimension changes >5 mm (range -37 to +16) occurred in 32 patients (97%). For axis measurements, the degree of lateral dimension changes were correlated with treatment field size (P=0.022) and degree of mucositis (P=0.017). Axis doses calculated for changed dimensions varied from those prescribed by -2.5 to +6% (median +2%). Differences larger than 5% were present in 4.8% of calculations. In 17 patients (52%), radiotherapy accessories had to be modified during treatment. The need to modify radiotherapy accessories correlated with larger treatment portals (P=0.004), more weight loss during treatment (P=0.01) and higher initial N stage (P=0.04). Conclusions: Changes of irradiated volume lateral dimensions during head and neck cancer radiotherapy may lead to considerable dose delivery inaccuracies. Watchful monitoring, corrections to calculated dose when changes observed are significant and radiotherapy accessories modification during the course of treatment are strongly recommended

  16. WE-AB-BRA-02: Development of Biomechanical Models to Describe Dose-Volume Response to Liver Stereotactic Body Radiation Therapy (SBRT) Patients

    Energy Technology Data Exchange (ETDEWEB)

    McCulloch, M; Polan, D; Feng, M; Lawrence, T; Haken, R Ten; Brock, K [University of Michigan, Ann Arbor, MI (United States)

    2015-06-15

    Purpose: Previous studies have shown that radiotherapy treatment for liver metastases causes marked liver hypertrophy in areas receiving low dose and atrophy/fibrosis in areas receiving high dose. The purpose of this work is to develop and evaluate a biomechanical model-based dose-response model to describe these liver responses to SBRT. Methods: In this retrospective study, a biomechanical model-based deformable registration algorithm, Morfeus, was expanded to include dose-based boundary conditions. Liver and tumor volumes were contoured on the planning images and CT/MR images three months post-RT and converted to finite element models. A thermal expansion-based relationship correlating the delivered dose and volume response was generated from 22 patients previously treated. This coefficient, combined with the planned dose, was applied as an additional boundary condition to describe the volumetric response of the liver of an additional cohort of metastatic liver patients treated with SBRT. The accuracy of the model was evaluated based on overall volumetric liver comparisons and the target registration error (TRE) using the average deviations in positions of identified vascular bifurcations on each set of registered images, with a target accuracy of the 2.5mm isotropic dose grid (vector dimension 4.3mm). Results: The thermal expansion coefficient models the volumetric change of the liver to within 3%. The accuracy of Morfeus with dose-expansion boundary conditions a TRE of 5.7±2.8mm compared to 11.2±3.7mm using rigid registration and 8.9±0.28mm using Morfeus with only spatial boundary conditions. Conclusion: A biomechanical model has been developed to describe the volumetric and spatial response of the liver to SBRT. This work will enable the improvement of correlating functional imaging with delivered dose, the mapping of the delivered dose from one treatment onto the planning images for a subsequent treatment, and will further provide information to assist

  17. Aggravation of dyspnea in stage I non-small cell lung cancer patients following stereotactic body radiotherapy: Is there a dose-volume dependency?

    DEFF Research Database (Denmark)

    Paludan, Merete; Hansen, Anders Traberg; Petersen, Jørgen B.B.

    2006-01-01

    the association of dose-volume histogram parameters with changes in dyspnea. The study concerns 28 medically inoperable stage I NSCLC patients that received SBRT at our department between 2000 and 2003. A central dose of 45 Gy/3 fractions was delivered in 5-8 days. WHO toxicity scoring of dyspnea...... was prospectively performed at baseline and during a 6-month follow-up post-SBRT. DVH parameters for pulmonary tissue were retrieved from the 3-D dose distributions.Aggravated dyspnea was registered in 11 patients (40%). We found no association between DVH parameters and changes in dyspnea. Nor did we find any...... consistent temporal variations of dyspnea after SBRT. We identified COPD as the factor showing the closest association with aggravation of dyspnea. The observed aggravation of dyspnea following SBRT reflects habitual exacerbations of COPD rather than treatment-related toxicity. Concern about pulmonary...

  18. Critical analysis of literature on low-dose synergy for use in screening chemical mixtures for risk assessment.

    Science.gov (United States)

    Boobis, Alan; Budinsky, Robert; Collie, Shanna; Crofton, Kevin; Embry, Michelle; Felter, Susan; Hertzberg, Richard; Kopp, David; Mihlan, Gary; Mumtaz, Moiz; Price, Paul; Solomon, Keith; Teuschler, Linda; Yang, Raymond; Zaleski, Rosemary

    2011-05-01

    There is increasing interest in the use of tiered approaches in risk assessment of mixtures or co-exposures to chemicals for prioritization. One possible screening-level risk assessment approach is the threshold of toxicological concern (TTC). To date, default assumptions of dose or response additivity have been used to characterize the toxicity of chemical mixtures. Before a screening-level approach could be used, it is essential to know whether synergistic interactions can occur at low, environmentally relevant exposure levels. Studies demonstrating synergism in mammalian test systems were identified from the literature, with emphasis on studies performed at doses close to the points of departure (PODs) for individual chemicals. This search identified 90 studies on mixtures. Few included quantitative estimates of low-dose synergy; calculations of the magnitude of interaction were included in only 11 papers. Quantitative methodology varied across studies in terms of the null hypothesis, response measured, POD used to test for synergy, and consideration of the slope of the dose-response curve. It was concluded that consistent approaches should be applied for quantification of synergy, including that synergy be defined in terms of departure from dose additivity; uniform procedures be developed for assessing synergy at low exposures; and the method for determining the POD for calculating synergy be standardized. After evaluation of the six studies that provided useful quantitative estimates of synergy, the magnitude of synergy at low doses did not exceed the levels predicted by additive models by more than a factor of 4.

  19. Dose-volume relationships for moderate or severe neck muscle atrophy after intensity-modulated radiotherapy in patients with nasopharyngeal carcinoma

    Science.gov (United States)

    Zhang, Lu-Lu; Wang, Xiao-Ju; Zhou, Guan-Qun; Tang, Ling-Long; Lin, Ai-Hua; Ma, Jun; Sun, Ying

    2015-01-01

    This study aimed to identify the dosimetric parameters and radiation dose tolerances associated with moderate or severe sternocleidomastoid muscle (SCM) atrophy after intensity-modulated radiotherapy (IMRT) in nasopharyngeal carcinoma (NPC). We retrospectively analysed 138 patients treated with IMRT between 2011 and 2012 for whom IMRT treatment plans and pretreatment and 3-year post-IMRT MRI scans were available. The association between mean dose (Dmean), maximum dose (Dmax), VX (% SCM volume that received more than X Gy), DX (dose to X% of the SCM volume) at X values of 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80 and SCM atrophy at 3 years after IMRT were analyzed. All dosimetric parameters, except V40, V50 and V80, were significantly associated with moderate or severe SCM atrophy. Multivariate analysis showed that V65 was an independent predictor of moderate or severe SCM atrophy (P atrophy. We suggest a limit of 21.47% for V65 to optimize NPC treatment planning, whilst minimizing the risk of moderate or severe SCM atrophy. PMID:26678599

  20. Relationship between Fidelity and Dose of Human Patient Simulation, Critical Thinking Skills, and Knowledge in an Associate Degree Nursing Program

    Science.gov (United States)

    Beebe, Rosella I.

    2012-01-01

    This study examined the relationship between human patient simulation (HPS), critical thinking skills, and knowledge acquisition after HPS was integrated across the curriculum of an associate degree nursing program to determine if differences existed in critical thinking and knowledge of students based on the fidelity of HPS used and amount of…

  1. Effects of first-dose volume and exercise on the efficacy and tolerability of bowel preparations for colonoscopy in Chinese people

    Directory of Open Access Journals (Sweden)

    Qin Y

    2016-04-01

    Full Text Available Ying Qin, Wei Liu, Songbai Lin, Xiangfeng Li International Medical Services, Peking Union Medical College Hospital, Beijing, People’s Republic of China Aim: This study was designed to compare the efficacy and tolerability of bowel preparations with and without the higher first-dose volume of polyethylene glycol (PEG solution or exercise after drinking PEG solution in Chinese people. Methods: A total of 330 participants who had a colonoscopy done in Peking Union Medical College Hospital were randomly and evenly assigned to three groups. Participants in Group A ingested 1 L PEG solution and then ingested 2 L PEG solution at a rate of 250 mL every 15 minutes. Participants in Group B ingested 3 L PEG solution at a rate of 250 mL every 15 minutes and then exercised more than 10 minutes after ingesting each liter of PEG solution. Participants in Group C ingested 3 L PEG solution at a rate of 250 mL every 15 minutes. Experienced gastrointestinal endoscopists rated the efficacy of bowel preparations based on the Boston Bowel Preparation Scale score. A questionnaire regarding participants’ symptoms associated with bowel preparations was administered to evaluate participants’ tolerability. Results: The three groups had insignificant difference in the percentages of participants’ symptoms including dizziness, nausea, stomach ache, bloating, and asthenia. However, the percentages of participants having hunger sensation, sleep disturbance, and anal discomfort were significantly higher in groups with the higher first-dose volume of PEG solution or exercise after drinking PEG solution than without them. The three groups had insignificant difference in the Boston Bowel Preparation Scale score. Conclusion: Whether to add the higher first-dose volume of PEG solution and exercise after drinking PEG solution or not, all participants achieved a similar quality of bowel preparations. Bowel preparations without the additional first-dose volume of PEG

  2. The Effect of Dose-Volume Parameters and Interfraction Interval on Cosmetic Outcome and Toxicity After 3-Dimensional Conformal Accelerated Partial Breast Irradiation

    International Nuclear Information System (INIS)

    Leonard, Kara Lynne; Hepel, Jaroslaw T.; Hiatt, Jessica R.; Dipetrillo, Thomas A.; Price, Lori Lyn; Wazer, David E.

    2013-01-01

    Purpose: To evaluate dose-volume parameters and the interfraction interval (IFI) as they relate to cosmetic outcome and normal tissue effects of 3-dimensional conformal radiation therapy (3D-CRT) for accelerated partial breast irradiation (APBI). Methods and Materials: Eighty patients were treated by the use of 3D-CRT to deliver APBI at our institutions from 2003-2010 in strict accordance with the specified dose-volume constraints outlined in the National Surgical Adjuvant Breast and Bowel Project B39/Radiation Therapy Oncology Group 0413 (NSABP-B39/RTOG 0413) protocol. The prescribed dose was 38.5 Gy in 10 fractions delivered twice daily. Patients underwent follow-up with assessment for recurrence, late toxicity, and overall cosmetic outcome. Tests for association between toxicity endpoints and dosimetric parameters were performed with the chi-square test. Univariate logistic regression was used to evaluate the association of interfraction interval (IFI) with these outcomes. Results: At a median follow-up time of 32 months, grade 2-4 and grade 3-4 subcutaneous fibrosis occurred in 31% and 7.5% of patients, respectively. Subcutaneous fibrosis improved in 5 patients (6%) with extended follow-up. Fat necrosis developed in 11% of women, and cosmetic outcome was fair/poor in 19%. The relative volume of breast tissue receiving 5%, 20%, 50%, 80%, and 100% (V5-V100) of the prescribed dose was associated with risk of subcutaneous fibrosis, and the volume receiving 50%, 80%, and 100% (V50-V100) was associated with fair/poor cosmesis. The mean IFI was 6.9 hours, and the minimum IFI was 6.2 hours. The mean and minimum IFI values were not significantly associated with late toxicity. Conclusions: The incidence of moderate to severe late toxicity, particularly subcutaneous fibrosis and fat necrosis and resulting fair/poor cosmesis, remains high with continued follow-up. These toxicity endpoints are associated with several dose-volume parameters. Minimum and mean IFI values were

  3. The Effect of Dose-Volume Parameters and Interfraction Interval on Cosmetic Outcome and Toxicity After 3-Dimensional Conformal Accelerated Partial Breast Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, Kara Lynne, E-mail: karalynne.kerr@gmail.com [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Hepel, Jaroslaw T. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Hiatt, Jessica R. [Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Dipetrillo, Thomas A. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Price, Lori Lyn [Department of Biostatistics Research Center, Institute of Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, Massachusetts (United States); Wazer, David E. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States)

    2013-03-01

    Purpose: To evaluate dose-volume parameters and the interfraction interval (IFI) as they relate to cosmetic outcome and normal tissue effects of 3-dimensional conformal radiation therapy (3D-CRT) for accelerated partial breast irradiation (APBI). Methods and Materials: Eighty patients were treated by the use of 3D-CRT to deliver APBI at our institutions from 2003-2010 in strict accordance with the specified dose-volume constraints outlined in the National Surgical Adjuvant Breast and Bowel Project B39/Radiation Therapy Oncology Group 0413 (NSABP-B39/RTOG 0413) protocol. The prescribed dose was 38.5 Gy in 10 fractions delivered twice daily. Patients underwent follow-up with assessment for recurrence, late toxicity, and overall cosmetic outcome. Tests for association between toxicity endpoints and dosimetric parameters were performed with the chi-square test. Univariate logistic regression was used to evaluate the association of interfraction interval (IFI) with these outcomes. Results: At a median follow-up time of 32 months, grade 2-4 and grade 3-4 subcutaneous fibrosis occurred in 31% and 7.5% of patients, respectively. Subcutaneous fibrosis improved in 5 patients (6%) with extended follow-up. Fat necrosis developed in 11% of women, and cosmetic outcome was fair/poor in 19%. The relative volume of breast tissue receiving 5%, 20%, 50%, 80%, and 100% (V5-V100) of the prescribed dose was associated with risk of subcutaneous fibrosis, and the volume receiving 50%, 80%, and 100% (V50-V100) was associated with fair/poor cosmesis. The mean IFI was 6.9 hours, and the minimum IFI was 6.2 hours. The mean and minimum IFI values were not significantly associated with late toxicity. Conclusions: The incidence of moderate to severe late toxicity, particularly subcutaneous fibrosis and fat necrosis and resulting fair/poor cosmesis, remains high with continued follow-up. These toxicity endpoints are associated with several dose-volume parameters. Minimum and mean IFI values were

  4. [Low dose volume histogram analysis of the lungs in prediction of acute radiation pneumonitis in patients with esophageal cancer treated with three-dimensional conformal radiotherapy].

    Science.gov (United States)

    Shen, Wen-bin; Zhu, Shu-chai; Gao, Hong-mei; Li, You-mei; Liu, Zhi-kun; Li, Juan; Su, Jing-wei; Wan, Jun

    2013-01-01

    To investigate the predictive value of low dose volume of the lung on acute radiation pneumonitis (RP) in patients with esophageal cancer treated with three-dimensional conformal radiotherapy (3D-CRT) only, and to analyze the relation of comprehensive parameters of the dose-volume V5, V20 and mean lung dose (MLD) with acute RP. Two hundred and twenty-two patients with esophageal cancer treated by 3D-CRT have been followed up. The V5-V30 and MLD were calculated from the dose-volume histogram system. The clinical factors and treatment parameters were collected and analyzed. The acute RP was evaluated according to the RTOG toxicity criteria. The acute RP of grade 1, 2, 3 and 4 were observed in 68 (30.6%), 40 (18.0%), 8 (3.6%) and 1 (0.5%) cases, respectively. The univariate analysis of measurement data:The primary tumor length, radiation fields, MLD and lung V5-V30 had a significant relationship with the acute RP. The magnitude of the number of radiation fields, the volume of GTV, MLD and Lung V5-V30 had a significant difference in whether the ≥ grade 1 and ≥ grade 2 acute RP developed or not. Binary logistic regression analysis showed that MLD, Lung V5, V20 and V25 were independent risk factors of ≥ grade 1 acute RP, and the radiation fields, MLD and Lung V5 were independent risk factors of ≥ grade 2 acute RP. The ≥ grade 1 and ≥ grade 2 acute RP were significantly decreased when MLD less than 14 Gy, V5 and V20 were less than 60% and 28%,respectively. When the V20 ≤ 28%, the acute RP was significantly decreased in V5 ≤ 60% group. When the MLD was ≤ 14 Gy, the ≥ 1 grade acute RP was significantly decreased in the V5 ≤ 60% group. When the MLD was >14 Gy, the ≥ grade 2 acute RP was significantly decreased in the V5 ≤ 60% group. The low dose volume of the lung is effective in predicting radiation pneumonitis in patients with esophageal cancer treated with 3D-CRT only. The comprehensive parameters combined with V5, V20 and MLD may increase the

  5. Acute kidney injury adjusted to volume status in critically ill patients: recognition of delayed diagnosis, restaging, and associated outcomes

    Directory of Open Access Journals (Sweden)

    Yacoub H

    2016-10-01

    Full Text Available Harout Yacoub,1 Leen Khoury,1 Youssef El Douaihy,1 Chadi Salmane,1 Jeanne Kamal,1 Marc Saad,2 Patricia Nasr,1 Jared Radbel,3 Elie El-Charabaty,1 Suzanne El-Sayegh1 1Department of Medicine, Staten Island University Hospital, Staten Island, NY, USA; 2Division of Renal Medicine, Emory University, Atlanta, GA, USA; 3Department of Pulmonary and Critical Care Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA Abstract: Critically ill patients receive a significant amount of fluids leading to a positive fluid balance; this dilutes serum creatinine resulting in an overestimated glomerular filtration rate. The goal of our study is to identify undiagnosed or underestimated acute kidney injury (AKI in the intensive care unit (ICU. It will also identify the morbidity and mortality associated with an underestimated AKI. We reviewed records of patients admitted to our institution (Staten Island University Hospital between 2012 and 2013 for more than 2 days. Patients with end stage renal disease were excluded. AKI was defined using the Acute Kidney Injury Network criteria. The following formula was used to identify and restage patients with AKI: adjusted creatinine = serum creatinine × [(hospital admission weight (kg 0.6 + Σ (daily cumulative fluid balance (L / hospital admission weight × 0.6]. The primary outcome identified newly diagnosed AKI and those who were restaged. The secondary outcome identified associated morbidities. Seven-hundred and thirty-three out of 1,982 ICU records reviewed, were used. Two-hundred and fifty-seven (mean age 69.8±14.9 had AKI, out of which 15.9% were restaged using the equation. Comparison of mean by Student’s t-test showed no difference between patients who were restaged. Similarly, chi-square revealed no differences between both arms, except mean admission weight (lower in patients who were restaged, fluid balance on days 1, 2, and 3 (higher in the restaged arm, and the presence of congestive

  6. A study to determine whether the volume-weighted computed tomography dose index gives reasonable estimates of organ doses for thai patients undergoing abdomen and pelvis computed tomography examinations

    Directory of Open Access Journals (Sweden)

    Supawitoo Sookpeng

    2017-01-01

    Full Text Available Introduction: Values for the CTDIvol, which is displayed on scanner consoles, give doses relative to a phantom much larger than most Thai patients, and the CTDIvoldoes not take account of differences in patient size, which affect organ doses. Objective: The purpose of this study was to evaluate relationships for size specific dose estimate (SSDE and volume weighted computed tomography (CT dose index (CTDIvol with patient size for CT scanners operating under automatic tube current modulation (ATCM. Methods: Retrospective data from 244 patients who had undergone abdomen and pelvis examination on GE and Siemens CT scanners were included in this study. The combination of anteroposterior (AP and lateral dimensions at the level of the first lumbar vertebra (L1 was used to represent patient size. Image noise within the liver was measured, and values of the absorbed dose for organs covered by the primary beam such as the liver, stomach and kidney were calculated using methods described in the literature. Values of CTDIvolwere recorded and SSDE calculated according to the American Association of Physics in Medicine (AAPM Report No.204. Linear regression models were used to evaluate the relationship between SSDE, CTDIvol, image noise and patient size. Results: SSDE is 20%-50% larger than the CTDIvol, with values for larger patients being more representative. Both the CTDIvoland image noise decreased with patient size for Siemens scanners, but the decline in SSDE was less significant. For the GE scanner, the CTDIvolwas a factor of 3-4 lower in small patients compared to larger ones, while the SSDE only decreased by a factor of two. Noise actually decreased slightly with patient size. Conclusion: Values of SSDE were similar to the doses calculated for the liver, stomach and kidney, which are covered by the primary beam, confirming that it provides a good estimate of organ-absorbed dose.

  7. DosedPet application for Nuclear Medicine: Calculation of the volume of medication needed for PET/CT patient; Aplicativo DosedPet para uso em Medicina Nuclear: calculo do volume de medicamento necessario para paciente de PET/CT

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Pedro Augusto do; Rodrigues, Araken dos S. Werneck, E-mail: pedroan88@gmail.com [Universidade de Brasilia (UnB), DF (Brazil). Programa de Pos Graduacao em Ciencias e Tecnologias em Saude

    2016-07-01

    This paper presents the application (APP) DosePet that calculates the amount of medicament for PET / CT in patients according to the predetermined radiation dose. The software has been designed using the web MIT App Inventor2 tool for Android platform. The application allows the workers to simulate the amount of radiation still existing in the facilities after the applications, increasing security and reducing exposures, and enable greater efficiency in the use of the radiopharmaceutical. (author)

  8. Cervical Gross Tumor Volume Dose Predicts Local Control Using Magnetic Resonance Imaging/Diffusion-Weighted Imaging—Guided High-Dose-Rate and Positron Emission Tomography/Computed Tomography—Guided Intensity Modulated Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Dyk, Pawel; Jiang, Naomi; Sun, Baozhou; DeWees, Todd A. [Department of Radiation Oncology, Washington University School of Medicine, St Louis, Missouri (United States); Fowler, Kathryn J.; Narra, Vamsi [Department of Diagnostic Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri (United States); Garcia-Ramirez, Jose L.; Schwarz, Julie K. [Department of Radiation Oncology, Washington University School of Medicine, St Louis, Missouri (United States); Grigsby, Perry W., E-mail: pgrigsby@wustl.edu [Department of Radiation Oncology, Washington University School of Medicine, St Louis, Missouri (United States); Division of Nuclear Medicine, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri (United States); Division of Gynecologic Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri (United States); Alvin J. Siteman Cancer Center, Washington University School of Medicine, St Louis, Missouri (United States)

    2014-11-15

    Purpose: Magnetic resonance imaging/diffusion weighted-imaging (MRI/DWI)-guided high-dose-rate (HDR) brachytherapy and {sup 18}F-fluorodeoxyglucose (FDG) — positron emission tomography/computed tomography (PET/CT)-guided intensity modulated radiation therapy (IMRT) for the definitive treatment of cervical cancer is a novel treatment technique. The purpose of this study was to report our analysis of dose-volume parameters predicting gross tumor volume (GTV) control. Methods and Materials: We analyzed the records of 134 patients with International Federation of Gynecology and Obstetrics stages IB1-IVB cervical cancer treated with combined MRI-guided HDR and IMRT from July 2009 to July 2011. IMRT was targeted to the metabolic tumor volume and lymph nodes by use of FDG-PET/CT simulation. The GTV for each HDR fraction was delineated by use of T2-weighted or apparent diffusion coefficient maps from diffusion-weighted sequences. The D100, D90, and Dmean delivered to the GTV from HDR and IMRT were summed to EQD2. Results: One hundred twenty-five patients received all irradiation treatment as planned, and 9 did not complete treatment. All 134 patients are included in this analysis. Treatment failure in the cervix occurred in 24 patients (18.0%). Patients with cervix failures had a lower D100, D90, and Dmean than those who did not experience failure in the cervix. The respective doses to the GTV were 41, 58, and 136 Gy for failures compared with 67, 99, and 236 Gy for those who did not experience failure (P<.001). Probit analysis estimated the minimum D100, D90, and Dmean doses required for ≥90% local control to be 69, 98, and 260 Gy (P<.001). Conclusions: Total dose delivered to the GTV from combined MRI-guided HDR and PET/CT-guided IMRT is highly correlated with local tumor control. The findings can be directly applied in the clinic for dose adaptation to maximize local control.

  9. Impact of β-lactam antibiotic therapeutic drug monitoring on dose adjustments in critically ill patients undergoing continuous renal replacement therapy.

    Science.gov (United States)

    Economou, Caleb J P; Wong, Gloria; McWhinney, Brett; Ungerer, Jacobus P J; Lipman, Jeffrey; Roberts, Jason A

    2017-05-01

    The objective of this study was to describe the effect of therapeutic drug monitoring (TDM) and dose adjustments of β-lactam antibiotics administered to critically ill patients undergoing continuous renal replacement therapy (CRRT) in a 30-bed tertiary intensive care unit (ICU). β-Lactam TDM data in our tertiary referral ICU were retrospectively reviewed. Clinical, demographic and dosing data were collected for patients administered β-lactam antibiotics while undergoing CRRT. The target trough concentration range was 1-10× the minimum inhibitory concentration (MIC). A total of 111 TDM samples from 76 patients (46 male) with a mean ± standard deviation age of 56.6 ± 15.9 years and weight of 89.1 ± 25.8 kg were identified. The duration of antibiotic therapy was between 2 days and 42 days. TDM identified a need for dose modification of β-lactam antibiotics in 39 (35%) instances; in 27 (24%) samples, TDM values resulted in decreasing the prescribed dose of β-lactam antibiotic whereas an increase in the prescribed dose occurred in 12 (11%) cases. In patients treated for hospital-acquired pneumonia and primary or secondary bacteraemia, the dose was required to be decreased in 10/25 (40%) and 7/46 (15%) cases, respectively, to attain target concentrations. β-Lactam TDM is a useful tool for guiding drug dosing in complex patients such as those receiving CRRT. Although over one-third of patients manifested concentrations outside the therapeutic range, most of these CRRT patients had excessive β-lactam concentrations. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  10. 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)

  11. 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.

  12. Radiation Therapy to the Plexus Brachialis in Breast Cancer Patients: Analysis of Paresthesia in Relation to Dose and Volume

    Energy Technology Data Exchange (ETDEWEB)

    Lundstedt, Dan, E-mail: dan.lundstedt@gu.se [Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg (Sweden); Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg (Sweden); Gustafsson, Magnus [Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg (Sweden); Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg (Sweden); Department of Therapeutic Radiation Physics, Sahlgrenska University Hospital, Gothenburg (Sweden); Steineck, Gunnar [Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg (Sweden); Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg (Sweden); Division of Clinical Cancer Epidemiology, Department of Oncology-Pathology, Karolinska Institute, Stockholm (Sweden); Sundberg, Agnetha [Department of Therapeutic Radiation Physics, Sahlgrenska University Hospital, Gothenburg (Sweden); Wilderäng, Ulrica [Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg (Sweden); Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg (Sweden); Holmberg, Erik [Regional Cancer Center, Sahlgrenska University Hospital, Gothenburg (Sweden); Johansson, Karl-Axel [Department of Therapeutic Radiation Physics, Sahlgrenska University Hospital, Gothenburg (Sweden); Karlsson, Per [Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg (Sweden)

    2015-06-01

    Purpose: To identify volume and dose predictors of paresthesia after irradiation of the brachial plexus among women treated for breast cancer. Methods and Materials: The women had breast surgery with axillary dissection, followed by radiation therapy with (n=192) or without irradiation (n=509) of the supraclavicular lymph nodes (SCLNs). The breast area was treated to 50 Gy in 2.0-Gy fractions, and 192 of the women also had 46 to 50 Gy to the SCLNs. We delineated the brachial plexus on 3-dimensional dose-planning computerized tomography. Three to eight years after radiation therapy the women answered a questionnaire. Irradiated volumes and doses were calculated and related to the occurrence of paresthesia in the hand. Results: After treatment with axillary dissection with radiation therapy to the SCLNs 20% of the women reported paresthesia, compared with 13% after axillary dissection without radiation therapy, resulting in a relative risk (RR) of 1.47 (95% confidence interval [CI] 1.02-2.11). Paresthesia was reported by 25% after radiation therapy to the SCLNs with a V{sub 40} {sub Gy} ≥ 13.5 cm{sup 3}, compared with 13% without radiation therapy, RR 1.83 (95% CI 1.13-2.95). Women having a maximum dose to the brachial plexus of ≥55.0 Gy had a 25% occurrence of paresthesia, with RR 1.86 (95% CI 0.68-5.07, not significant). Conclusion: Our results indicate that there is a correlation between larger irradiated volumes of the brachial plexus and an increased risk of reported paresthesia among women treated for breast cancer.

  13. Determination of neutron dose from criticality accidents with bioassays for sodium-24 in blood and phosphorus-32 in hair

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Y.; Miller, L.F. [Tennessee Univ., Knoxville, TN (United States); Brown, K.S.; Casson, W.H.; Mei, G.T.; Thein, M. [Oak Ridge National Lab., TN (United States)

    1993-06-01

    A comprehensive review of accident neutron dosimetry using blood and hair analysis was performed and is summarized in this report. Experiments and calculations were conducted at Oak Ridge National Laboratory (ORNL) and the University of Tennessee (UT) to develop measurement techniques for the activity of {sup 24}Na in blood and {sup 32}P in hair for nuclear accident dosimetry. An operating procedure was established for the measurement of {sup 24}Na in blood using an HPGe detector system. The sensitivity of the measurement for a 20-mL sample is 0.01-0.02 Gy of total neutron dose for hard spectra and below 0.005 Gy for soft spectra based on a 30- to 60-min counting time. The operating procedures for direct counting of hair samples are established using a liquid scintillation detector. Approximately 0.06-0.1 Gy of total neutron dose can be measured from a 1-g hair sample using this procedure. Detailed procedures for chemical dissolution and ashing of hair samples are also developed. A method is proposed to use blood and hair analysis for assessing neutron dose based on a collection of 98 neutron spectra. Ninety-eight blood activity-to-dose conversion factors were calculated. The calculated results for an uncollided fission spectrum compare favorably with previously published data for fission neutrons. This nuclear accident dosimetry system makes it possible to estimate an individual`s neutron dose within a few hours after an accident if the accident spectrum can be approximated from one of 98 tabulated neutron spectrum descriptions. If the information on accident and spectrum description is not available, the activity ratio of {sup 32}P in hair and {sup 24}Na in blood can provide information related to the neutron spectrum for dose assessment.

  14. Determination of neutron dose from criticality accidents with bioassays for sodium-24 in blood and phosphorus-32 in hair

    International Nuclear Information System (INIS)

    Feng, Y.; Miller, L.F.; Brown, K.S.; Casson, W.H.; Mei, G.T.; Thein, M.

    1993-06-01

    A comprehensive review of accident neutron dosimetry using blood and hair analysis was performed and is summarized in this report. Experiments and calculations were conducted at Oak Ridge National Laboratory (ORNL) and the University of Tennessee (UT) to develop measurement techniques for the activity of 24 Na in blood and 32 P in hair for nuclear accident dosimetry. An operating procedure was established for the measurement of 24 Na in blood using an HPGe detector system. The sensitivity of the measurement for a 20-mL sample is 0.01-0.02 Gy of total neutron dose for hard spectra and below 0.005 Gy for soft spectra based on a 30- to 60-min counting time. The operating procedures for direct counting of hair samples are established using a liquid scintillation detector. Approximately 0.06-0.1 Gy of total neutron dose can be measured from a 1-g hair sample using this procedure. Detailed procedures for chemical dissolution and ashing of hair samples are also developed. A method is proposed to use blood and hair analysis for assessing neutron dose based on a collection of 98 neutron spectra. Ninety-eight blood activity-to-dose conversion factors were calculated. The calculated results for an uncollided fission spectrum compare favorably with previously published data for fission neutrons. This nuclear accident dosimetry system makes it possible to estimate an individual's neutron dose within a few hours after an accident if the accident spectrum can be approximated from one of 98 tabulated neutron spectrum descriptions. If the information on accident and spectrum description is not available, the activity ratio of 32 P in hair and 24 Na in blood can provide information related to the neutron spectrum for dose assessment

  15. Predictive factors for Child-Pugh score elevation in hepatocellular carcinoma patients treated with conformal radiation therapy: dose-volume histogram analysis.

    Science.gov (United States)

    Yu, Jeong Il; Park, Hee Chul; Lim, Do Hoon; Park, Woo Yoon

    2013-01-01

    We designed the study to identify the clinical and dose-volumetric parameters associated with the risk of Child-Pugh score elevation in hepatocellular carcinoma patients treated with conformal radiation therapy. All 161 hepatocellular carcinoma patients in the study underwent 4D-computed tomography simulation, and a dose-volume histogram was generated after radiotherapy planning. Patients who had an elevated Child-Pugh (e-CP) score of 2 or more without progressive disease within 3 months were defined as e-CP positive. Twenty-six of 142 patients without progressive disease were e-CP positive. Pretreatment Child-Pugh class, further treatment within 30 days of radiotherapy, lymph node metastasis, mean liver dose, V(20 Gy), V(25 Gy), and V(30 Gy) were significantly correlated with e-CP positivity. The e-CP developed in 13 of 106 patients (12.3%) with V(30 Gy) of ≤28.1% and in 13 of 36 patients (36.1%) with V(30 Gy) >28.1% (P = 0.001). Our data demonstrate that mean liver dose, V(10 Gy), V(20 Gy), V(25 Gy), and V(30 Gy) are independent dose-volumetric predictors for e-CP positivity in hepatocellular carcinoma patients treated with conformal radiation therapy. V(30 Gy) should be limited to less than 28.1% to minimize the risk of e-CP.

  16. DosedPet application for Nuclear Medicine: Calculation of the volume of medication needed for PET/CT patient

    International Nuclear Information System (INIS)

    Nascimento, Pedro Augusto do; Rodrigues, Araken dos S. Werneck

    2016-01-01

    This paper presents the application (APP) DosePet that calculates the amount of medicament for PET / CT in patients according to the predetermined radiation dose. The software has been designed using the web MIT App Inventor2 tool for Android platform. The application allows the workers to simulate the amount of radiation still existing in the facilities after the applications, increasing security and reducing exposures, and enable greater efficiency in the use of the radiopharmaceutical. (author)

  17. The renal and neurohumoral effects of the addition of low-dose dopamine in septic critically ill patients

    NARCIS (Netherlands)

    Girbes, ARJ; Patten, MT; McCloskey, BV; Groeneveld, ABJ; Hoogenberg, K

    2000-01-01

    Objectives: Dopamine exerts a complicated action on the cardiovascular-renal and neurohumoral systems. We evaluated the effects of the addition of different doses of dopamine on top of treatment with norepinephrine on the haemodynamics, renal function and neurohormones of septic shock patients.

  18. Evaluation of radiation dose and positioning accuracy on X-ray volume imaging system for image-guided radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jason Chia-Hsien [Division of Radiation Oncology, Department of Oncology, and Cancer Research Center, National Taiwan University Hospital, Taipei, Taiwan (China); Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan (China); Liang, C.-H. [Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan (China); Wu, J.-K. [Division of Radiation Oncology, Department of Oncology, and Cancer Research Center, National Taiwan University Hospital, Taipei, Taiwan (China); Huang, K.-M. [Division of Radiation Oncology, Department of Oncology, and Cancer Research Center, National Taiwan University Hospital, Taipei, Taiwan (China); Department of Radiological Technology, Yuanpei University, Hsinchu, Taiwan (China); Wu, T.-H. [Department of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan (China); Tsai, C.-J.; Chen, C.-L. [Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan (China); Lee, Jason J.S. [Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan (China)], E-mail: jslee@ym.edu.tw

    2008-05-15

    Linear accelerators equipped with X-ray volumetric cone-beam Imaging (XVI) system enable verification of location of patients and displacement of tumors for image-guided radiotherapy (IGRT). The objective of this study is to evaluate the positioning accuracy using the XVI system for image-guided patient setup and to establish a lower-dose imaging protocol without sacrificing positioning accuracy for routine treatment courses. Several low-dose imaging protocols are proposed by modifying tube voltage from 120 to 100 kV and lowering tube current from 40 to 10 mA. The positioning accuracy of both bone and gray value registration methods provided by XVI system were also evaluated. Phantom study revealed that the gray value algorithm was more accurate than the bone algorithm in position and registration. However, both translational and rotational accuracies were less than 0.15 mm and 0.8' deg. at all dimensions, which were considered negligible in clinical applications. In addition, the lower-dose protocol (100 kV, 10 mA) produced relative much less radiation dose compared to the default CBCT protocol in the XVI system. In conclusion, our proposed lower-dose protocol results in significant radiation dose reduction without compromising positioning accuracy and may have the potential to be adopted for clinical usage in the future.

  19. Emphysema quantification on low-dose CT using percentage of low-attenuation volume and size distribution of low-attenuation lung regions: Effects of adaptive iterative dose reduction using 3D processing

    Energy Technology Data Exchange (ETDEWEB)

    Nishio, Mizuho, E-mail: nmizuho@med.kobe-u.ac.jp [Advanced Biomedical Imaging Research Center, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017 (Japan); Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017 (Japan); Matsumoto, Sumiaki, E-mail: sumatsu@med.kobe-u.ac.jp [Advanced Biomedical Imaging Research Center, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017 (Japan); Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017 (Japan); Seki, Shinichiro, E-mail: sshin@med.kobe-u.ac.jp [Division of Radiology, Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017 (Japan); Koyama, Hisanobu, E-mail: hkoyama@med.kobe-u.ac.jp [Division of Radiology, Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017 (Japan); Ohno, Yoshiharu, E-mail: yosirad@kobe-u.ac.jp [Advanced Biomedical Imaging Research Center, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017 (Japan); Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017 (Japan); Fujisawa, Yasuko, E-mail: yasuko1.fujisawa@toshiba.co.jp [Toshiba Medical Systems Corporation, 1385 Shimoishigami, Otawara, Tochigi 324-8550 (Japan); Sugihara, Naoki, E-mail: naoki.sugihara@toshiba.co.jp [Toshiba Medical Systems Corporation, 1385 Shimoishigami, Otawara, Tochigi 324-8550 (Japan); and others

    2014-12-15

    Highlights: • Emphysema quantification (LAV% and D) was affected by image noise on low-dose CT. • For LAV% and D, AIDR 3D improved agreement of quantification on low-dose CT. • AIDR 3D has the potential to quantify emphysema accurately on low-dose CT. - Abstract: Purpose: To evaluate the effects of adaptive iterative dose reduction using 3D processing (AIDR 3D) for quantification of two measures of emphysema: percentage of low-attenuation volume (LAV%) and size distribution of low-attenuation lung regions. Method and materials: : Fifty-two patients who underwent standard-dose (SDCT) and low-dose CT (LDCT) were included. SDCT without AIDR 3D, LDCT without AIDR 3D, and LDCT with AIDR 3D were used for emphysema quantification. First, LAV% was computed at 10 thresholds from −990 to −900 HU. Next, at the same thresholds, linear regression on a log–log plot was used to compute the power law exponent (D) for the cumulative frequency-size distribution of low-attenuation lung regions. Bland–Altman analysis was used to assess whether AIDR 3D improved agreement between LDCT and SDCT for emphysema quantification of LAV% and D. Results: The mean relative differences in LAV% between LDCT without AIDR 3D and SDCT were 3.73%–88.18% and between LDCT with AIDR 3D and SDCT were −6.61% to 0.406%. The mean relative differences in D between LDCT without AIDR 3D and SDCT were 8.22%–19.11% and between LDCT with AIDR 3D and SDCT were 1.82%–4.79%. AIDR 3D improved agreement between LDCT and SDCT at thresholds from −930 to −990 HU for LAV% and at all thresholds for D. Conclusion: AIDR 3D improved the consistency between LDCT and SDCT for emphysema quantification of LAV% and D.

  20. Toxicity and efficacy of re-irradiation of high-grade glioma in a phase I dose- and volume escalation trial

    DEFF Research Database (Denmark)

    Møller, Søren; Munck Af Rosenschöld, Per; Costa, Junia

    2017-01-01

    INTRODUCTION: The purpose of this study was to evaluate the safety and efficacy of PET and MRI guided re-irradiation of recurrent high-grade glioma (HGG) and to assess the impact of radiotherapy dose, fractionation and irradiated volume. MATERIAL AND METHODS: Patients with localized, recurrent HGG...... (grades III-IV) and no other treatment options were eligible for a prospective phase I trial. Gross tumor volumes for radiotherapy were defined using T1-contrast enhanced MRI and (18)F-fluoro-ethyl tyrosine PET. Radiotherapy was delivered using volumetric modulated arc therapy with a 2-mm margin. The dose...... prescription of four consecutive groups was (1) 35 Gy/10fr., (2) 42 Gy/10fr., (3) 29.5 Gy/5fr. and (4) 35 Gy/10fr. to larger tumor volumes (100-300 cm(3)), respectively. RESULTS: Thirty-one patients were treated of which 81% had glioblastoma. The median progression-free survival was 2.8 months (95%CI: 2.1-3...

  1. Irradiation of blood, blood compounds and cell culture in equipment of radiotherapy of clinical usage. Study about volume and ideal dose

    International Nuclear Information System (INIS)

    Fernandes, Marco Antonio Rodrigues; Pereira, Adelino Jose; Novaes, Paulo Eduardo Ribeiro dos Santos

    1996-01-01

    The irradiation of blood bags with the objective of minimizing the graft-versus-host disease in the proceedings of blood transfusion has been consolidated as an indispensable step in the advances of hematopoietic system diseases therapeutics. This practice performed in the great oncological treatment centers requires appropriate equipment (cell irradiators), that due to the high coast, is inaccessible to the majority of the services. The main objective of this work is the show the technique developed by the Radiological Physics Service of the Hospital A. C. Camargo Radiation Department, using the teletherapy equipment of clinical usage available at the Institution. The literature shows that a total dose of 2000 to 3500 c Gy must be administered to all target volume to get an ideal dose/volume relation that proportionates better therapeutic results, neutralizing the cells which are causative of post transfusion reactions of rejection, without prejudicing the other cells that are necessary to the maintenance and preservation of the transplanted person's hematopoietic system functions. With the technic developed for optimization of the irradiation. it is possible to conclude that the utilization of radiotherapy equipment of clinical usage for blood irradiation, substituting cells irradiators, is a good option, permitting safe transfusion of products irradiated with adequate dose. (author)

  2. Should the bladder be full or empty during gynecologic brachytherapy applications? A bladder dose volume histogram analysis and implications for treatment

    International Nuclear Information System (INIS)

    Dusenbery, Kathryn E.; Lewandowski, Loretta A.; Higgins, Patrick D.

    1996-01-01

    Purpose: Chronic radiation cystitis is an uncommon but debilitating late complication of definitive external beam (EB) and brachytherapy (BT) for cervix cancer. During BT an indwelling catheter is usually placed in the bladder, collapsing it closer to the BT sources. We have devised a method to deliver BT with a full bladder. The difference in bladder dose in the full and empty state were analyzed during definitive EBT and BT for cervix cancer. Methods: The technique of Lyman and Wolbarst (1) were used to evaluate the bladder complication probability for a representative cervix cancer patient undergoing EBT and BT. DVHs were generated from CT scans obtained with a full and empty bladder. Three possible dose prescriptions were analyzed. Results: The DVH for the full and empty situations are shown. With the bladder full, the volume of bladder predicted to receive ≥ 80 Gy was approximately 10% for all dose schemes evaluated, whereas with the bladder empty, up to 50% of the bladder volume received ≥ 80 Gy. Conclusions: A distended bladder improves the DVH. A technique for performing full bladder LDR brachytherapy will be discussed

  3. Modeling aeolian transport of soil-bound plutonium: considering infrequent but normal environmental disturbances is critical in estimating future dose.

    Science.gov (United States)

    Michelotti, Erika A; Whicker, Jeffrey J; Eisele, William F; Breshears, David D; Kirchner, Thomas B

    2013-06-01

    Dose assessments typically consider environmental systems as static through time, but environmental disturbances such as drought and fire are normal, albeit infrequent, events that can impact dose-influential attributes of many environmental systems. These phenomena occur over time frames of decades or longer, and are likely to be exacerbated under projected warmer, drier climate. As with other types of dose assessment, the impacts of environmental disturbances are often overlooked when evaluating dose from aeolian transport of radionuclides and other contaminants. Especially lacking are predictions that account for potential changing vegetation cover effects on radionuclide transport over the long time frames required by regulations. A recently developed dynamic wind-transport model that included vegetation succession and environmental disturbance provides more realistic long-term predictability. This study utilized the model to estimate emission rates for aeolian transport, and compare atmospheric dispersion and deposition rates of airborne plutonium-contaminated soil into neighboring areas with and without environmental disturbances. Specifically, the objective of this study was to utilize the model results as input for a widely used dose assessment model (CAP-88). Our case study focused on low levels of residual plutonium found in soils from past operations at Los Alamos National Laboratory (LANL), in Los Alamos, NM, located in the semiarid southwestern USA. Calculations were conducted for different disturbance scenarios based on conditions associated with current climate, and a potential future drier and warmer climate. Known soil and sediment concentrations of plutonium were used to model dispersal and deposition of windblown residual plutonium, as a function of distance and direction. Environmental disturbances that affected vegetation cover included ground fire, crown fire, and drought, with reoccurrence rates for current climate based on site historical

  4. Modeling aeolian transport of soil-bound plutonium: considering infrequent but normal environmental disturbances is critical in estimating future dose

    International Nuclear Information System (INIS)

    Michelotti, Erika A.; Whicker, Jeffrey J.; Eisele, William F.; Breshears, David D.; Kirchner, Thomas B.

    2013-01-01

    Dose assessments typically consider environmental systems as static through time, but environmental disturbances such as drought and fire are normal, albeit infrequent, events that can impact dose-influential attributes of many environmental systems. These phenomena occur over time frames of decades or longer, and are likely to be exacerbated under projected warmer, drier climate. As with other types of dose assessment, the impacts of environmental disturbances are often overlooked when evaluating dose from aeolian transport of radionuclides and other contaminants. Especially lacking are predictions that account for potential changing vegetation cover effects on radionuclide transport over the long time frames required by regulations. A recently developed dynamic wind-transport model that included vegetation succession and environmental disturbance provides more realistic long-term predictability. This study utilized the model to estimate emission rates for aeolian transport, and compare atmospheric dispersion and deposition rates of airborne plutonium-contaminated soil into neighboring areas with and without environmental disturbances. Specifically, the objective of this study was to utilize the model results as input for a widely used dose assessment model (CAP-88). Our case study focused on low levels of residual plutonium found in soils from past operations at Los Alamos National Laboratory (LANL), in Los Alamos, NM, located in the semiarid southwestern USA. Calculations were conducted for different disturbance scenarios based on conditions associated with current climate, and a potential future drier and warmer climate. Known soil and sediment concentrations of plutonium were used to model dispersal and deposition of windblown residual plutonium, as a function of distance and direction. Environmental disturbances that affected vegetation cover included ground fire, crown fire, and drought, with reoccurrence rates for current climate based on site historical

  5. Low-Dose Bone Morphogenetic Protein-2/Stromal Cell-Derived Factor-1β Cotherapy Induces Bone Regeneration in Critical-Size Rat Calvarial Defects

    Science.gov (United States)

    Herberg, Samuel; Susin, Cristiano; Pelaez, Manuel; Howie, R. Nicole; Moreno de Freitas, Rubens; Lee, Jaebum; Cray, James J.; Johnson, Maribeth H.; Elsalanty, Mohammed E.; Hamrick, Mark W.; Isales, Carlos M.; Wikesjö, Ulf M.E.

    2014-01-01

    Increasing evidence suggests that stromal cell-derived factor-1 (SDF-1/CXCL12) is involved in bone formation, though underlying molecular mechanisms remain to be fully elucidated. Also, contributions of SDF-1β, the second most abundant splice variant, as an osteogenic mediator remain obscure. We have shown that SDF-1β enhances osteogenesis by regulating bone morphogenetic protein-2 (BMP-2) signaling in vitro. Here we investigate the dose-dependent contribution of SDF-1β to suboptimal BMP-2-induced local bone formation; that is, a dose that alone would be too low to significantly induce bone formation. We utilized a critical-size rat calvarial defect model and tested the hypotheses that SDF-1β potentiates BMP-2 osteoinduction and that blocking SDF-1 signaling reduces the osteogenic potential of BMP-2 in vivo. In preliminary studies, radiographic analysis at 4 weeks postsurgery revealed a dose-dependent relationship in BMP-2-induced new bone formation. We then found that codelivery of SDF-1β potentiates suboptimal BMP-2 (0.5 μg) osteoinduction in a dose-dependent order, reaching comparable levels to the optimal BMP-2 dose (5.0 μg) without apparent adverse effects. Blocking the CXC chemokine receptor 4 (CXCR4)/SDF-1 signaling axis using AMD3100 attenuated the osteoinductive potential of the optimal BMP-2 dose, confirmed by qualitative histologic analysis. In conclusion, SDF-1β provides potent synergistic effects that support BMP-induced local bone formation and thus appears a suitable candidate for optimization of bone augmentation using significantly lower amounts of BMP-2 in spine, orthopedic, and craniofacial settings. PMID:24341891

  6. Evaluation of critical pathways, radionuclides, and remedial measures for reducing the radiological dose to returning populations at a former nuclear test site

    Energy Technology Data Exchange (ETDEWEB)

    Robison, W. L., LLNL

    1997-11-01

    Bikini Island, the major residence island at Bikini Atoll, was contaminated with radioactive fallout as a result of the BRAVO test conducted on March 1, 1954. We have identified the critical radionuclides and supplied radiological data needed to develop dose estimates for all possible exposure pathways. These estimates show that the major dose to returning populations would result from ingestion of cesium-137 (137 Cs) in locally grown terrestrial foods where the predicted population average effective dose exceeds current federal guidelines. Consequently, we designed several long-term field experiments to develop and evaluate methods to reduce the 137 Cs content in locally grown foods.This paper gives a general outline of the remediation experiments with a more detailed description of a preferred combined option. Our comparative evaluation on various remedial methods show that the combined option--potassium treatment of the entire islands with limited excavation of soil in village an d housing areas--will be effective in reducing the dose to about 10% of pretreatment levels, and offers very significant benefits with respect to adverse environmental impacts as well as savings in overall costs, time, and required expert resources.

  7. Challenging the One-Dose-Fits-All Model for Insulin in the Acute Treatment of Pediatric Diabetic Ketoacidosis. A Critical Appraisal of "Low-Dose Versus Standard-Dose Insulin in Pediatric Diabetic Ketoacidosis: A Randomized Clinical Trial" by Nallasamy et al (JAMA Pediatrics 2014; 168:999-1005).

    Science.gov (United States)

    Orwoll, Benjamin Edward

    2016-10-01

    To review the findings and discuss the implications of the use of low-dose insulin infusions in pediatric diabetic ketoacidosis compared with standard-dose insulin. A search of the electronic PubMed database was used to perform the clinical query as well as to search for additional relevant literature. The article by Nallasamy K et al "Low-Dose vs Standard-Dose Insulin in Pediatric Diabetic Ketoacidosis: A Randomized Clinical Trial. JAMA Pediatrics 2014; 17:e477-e480" was selected for critical appraisal and literature review. The authors performed a randomized controlled trial among 50 consecutive patients of 0-12 years old presenting to the emergency department in diabetic ketoacidosis. They found that low-dose (0.05 U/kg/hr) insulin infusion was noninferior to standard-dose (0.1 U/kg/hr) insulin in terms of resolution of hyperglycemia and acidosis with a trend toward lower rates of therapy-related complications in the low-dose group. Low-dose insulin infusion is noninferior to standard-dose insulin in the treatment of younger pediatric patients with diabetic ketoacidosis and may lead to fewer therapy-related complications.

  8. Dose-Volume Histogram Predictors of Chronic Gastrointestinal Complications After Radical Hysterectomy and Postoperative Concurrent Nedaplatin-Based Chemoradiation Therapy for Early-Stage Cervical Cancer

    International Nuclear Information System (INIS)

    Isohashi, Fumiaki; Yoshioka, Yasuo; Mabuchi, Seiji; Konishi, Koji; Koizumi, Masahiko; Takahashi, Yutaka; Ogata, Toshiyuki; Maruoka, Shintaroh; Kimura, Tadashi; Ogawa, Kazuhiko

    2013-01-01

    Purpose: The purpose of this study was to evaluate dose-volume histogram (DVH) predictors for the development of chronic gastrointestinal (GI) complications in cervical cancer patients who underwent radical hysterectomy and postoperative concurrent nedaplatin-based chemoradiation therapy. Methods and Materials: This study analyzed 97 patients who underwent postoperative concurrent chemoradiation therapy. The organs at risk that were contoured were the small bowel loops, large bowel loop, and peritoneal cavity. DVH parameters subjected to analysis included the volumes of these organs receiving more than 15, 30, 40, and 45 Gy (V15-V45) and their mean dose. Associations between DVH parameters or clinical factors and the incidence of grade 2 or higher chronic GI complications were evaluated. Results: Of the clinical factors, smoking and low body mass index (BMI) (<22) were significantly associated with grade 2 or higher chronic GI complications. Also, patients with chronic GI complications had significantly greater V15-V45 volumes and higher mean dose of the small bowel loops compared with those without GI complications. In contrast, no parameters for the large bowel loop or peritoneal cavity were significantly associated with GI complications. Results of the receiver operating characteristics (ROC) curve analysis led to the conclusion that V15-V45 of the small bowel loops has high accuracy for prediction of GI complications. Among these parameters, V40 gave the highest area under the ROC curve. Finally, multivariate analysis was performed with V40 of the small bowel loops and 2 other clinical parameters that were judged to be potential risk factors for chronic GI complications: BMI and smoking. Of these 3 parameters, V40 of the small bowel loops and smoking emerged as independent predictors of chronic GI complications. Conclusions: DVH parameters of the small bowel loops may serve as predictors of grade 2 or higher chronic GI complications after postoperative

  9. SU-E-T-170: Characterization of the Location, Extent, and Proximity to Critical Structures of Target Volumes Provides Detail for Improved Outcome Predictions Among Pancreatic Cancer Patients

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Z; Moore, J; Rosati, L; Mian, O; Narang, A; Herman, J; McNutt, T [Johns Hopkins University, Baltimore, MD (United States)

    2015-06-15

    Purpose: In radiotherapy, size, location and proximity of the target to critical structures influence treatment decisions. It has been shown that proximity of the target predicts dosimetric sparing of critical structures. In addition to dosimetry, precise location of disease has further implications such as tumor invasion, or proximity to major arteries that inhibit surgery. Knowledge of which patients can be converted to surgical candidates by radiation may have high impact on future treat/no-treat decisions. We propose a method to improve our characterization of the location of pancreatic cancer and treatment volume extent with respect to nearby arteries with the goal of developing features to improve clinical predictions and decisions. Methods: Oncospace is a local learning health system that systematically captures clinical outcomes and all aspects of radiotherapy treatment plans, including overlap volume histograms (OVH) – a measure of spatial relationships between two structures. Minimum and maximum distances of PTV and OARs based on OVH, PTV volume, anatomic location by ICD-9 code, and surgical outcome were queried. Normalized distance to center from the left and right kidney was calculated to indicate tumor location and laterality. Distance to critical arteries (celiac, superior mesenteric, common hepatic) is validated by surgical status (borderline resectable, locally advanced converted to resectable). Results: There were 205 pancreas stereotactic body radiotherapy patients treated from 2009–2015 queried. Location/laterality of tumor based on kidney OVH show strong trends between location by OVH and by ICD-9. Compared to the locally advanced group, the borderline resectable group showed larger geometrical distance from critical arteries (p=0.03). Conclusion: Our platform enabled analysis of shape/size-location relationships. These data suggest that PTV volume and attention to distance between PTVs and surrounding OARs and major arteries may be

  10. SU-E-T-170: Characterization of the Location, Extent, and Proximity to Critical Structures of Target Volumes Provides Detail for Improved Outcome Predictions Among Pancreatic Cancer Patients

    International Nuclear Information System (INIS)

    Cheng, Z; Moore, J; Rosati, L; Mian, O; Narang, A; Herman, J; McNutt, T

    2015-01-01

    Purpose: In radiotherapy, size, location and proximity of the target to critical structures influence treatment decisions. It has been shown that proximity of the target predicts dosimetric sparing of critical structures. In addition to dosimetry, precise location of disease has further implications such as tumor invasion, or proximity to major arteries that inhibit surgery. Knowledge of which patients can be converted to surgical candidates by radiation may have high impact on future treat/no-treat decisions. We propose a method to improve our characterization of the location of pancreatic cancer and treatment volume extent with respect to nearby arteries with the goal of developing features to improve clinical predictions and decisions. Methods: Oncospace is a local learning health system that systematically captures clinical outcomes and all aspects of radiotherapy treatment plans, including overlap volume histograms (OVH) – a measure of spatial relationships between two structures. Minimum and maximum distances of PTV and OARs based on OVH, PTV volume, anatomic location by ICD-9 code, and surgical outcome were queried. Normalized distance to center from the left and right kidney was calculated to indicate tumor location and laterality. Distance to critical arteries (celiac, superior mesenteric, common hepatic) is validated by surgical status (borderline resectable, locally advanced converted to resectable). Results: There were 205 pancreas stereotactic body radiotherapy patients treated from 2009–2015 queried. Location/laterality of tumor based on kidney OVH show strong trends between location by OVH and by ICD-9. Compared to the locally advanced group, the borderline resectable group showed larger geometrical distance from critical arteries (p=0.03). Conclusion: Our platform enabled analysis of shape/size-location relationships. These data suggest that PTV volume and attention to distance between PTVs and surrounding OARs and major arteries may be

  11. DART-bid (Dose-differentiated accelerated radiation therapy, 1.8 Gy twice daily)–a novel approach for non-resected NSCLC: final results of a prospective study, correlating radiation dose to tumor volume

    International Nuclear Information System (INIS)

    Wurstbauer, Karl; Sedlmayer, Felix; Deutschmann, Heinz; Dagn, Karin; Kopp, Peter; Zehentmayr, Franz; Lamprecht, Bernd; Porsch, Peter; Wegleitner, Birgit; Studnicka, Michael

    2013-01-01

    Sequential chemo-radiotherapies with intensive radiation components deliver promising results in non-resected non-small cell lung cancer (NSCLC). In general, radiation doses are determined by dose constraints for normal tissues, not by features relevant for tumor control. DART-bid targets directly the doses required for tumor control, correlating doses to tumor volume in a differentiated mode. Radiation doses to primary tumors were aligned along increasing tumor size within 4 groups (<2.5 cm/2.5–4.5 cm/4.5–6.0 cm/>6.0 cm; mean number of three perpendicular diameters). ICRU-doses of 73.8 Gy/79.2 Gy/84.6 Gy/90.0 Gy, respectively, were applied. Macroscopically involved nodes were treated with a median dose of 59.4 Gy, nodal sites about 6 cm cranial to involved nodes electively with 45 Gy. Fractional doses were 1.8 Gy twice daily (bid). 2 cycles chemotherapy were given before radiotherapy. Between 2004 and 2009, 160 not selected patients with 164 histologically/cytologically proven NSCLC were enrolled; Stage I: 38 patients; II: 6 pts.; IIIA: 69 pts.; IIIB: 47 pts. Weight loss >5%/3 months: 38 patients (24%). Primary endpoints are local and regional tumor control rates at 2 years (as >90% of locoregional failures occur within 2 years). Secondary endpoints are survival and toxicity. With a minimum follow-up time of 2 years for patients alive, the final results are presented. 32 local and 10 regional recurrences occurred. The local and regional tumor control rates at 2 years are 77% and 93%, respectively. The median overall survival (OS) time is 28.0 months, the 2- and 5-year OS rates are 57% and 19%, respectively. For stage III patients, median OS amounts to 24.3 months, 2- /5-year OS rates to 51% and 18%, respectively. 2 treatment-related deaths (progressive pulmonary fibrosis) occurred in patients with pre-existing pulmonary fibrosis. Further acute and late toxicity was mild. This novel approach yields a high level of locoregional tumor control and survival times

  12. Treatment of Locally Advanced Vaginal Cancer With Radiochemotherapy and Magnetic Resonance Image-Guided Adaptive Brachytherapy: Dose-Volume Parameters and First Clinical Results

    Energy Technology Data Exchange (ETDEWEB)

    Dimopoulos, Johannes C.A. [Department of Radiation Oncology, Metropolitan Hospital, Athens (Greece); Schmid, Maximilian P., E-mail: maximilian.schmid@akhwien.at [Department of Radiotherapy, Medical University of Vienna, Vienna (Austria); Fidarova, Elena; Berger, Daniel; Kirisits, Christian; Poetter, Richard [Department of Radiotherapy, Medical University of Vienna, Vienna (Austria)

    2012-04-01

    Purpose: To investigate the clinical feasibility of magnetic resonance image-guided adaptive brachytherapy (IGABT) for patients with locally advanced vaginal cancer and to report treatment outcomes. Methods and Materials: Thirteen patients with vaginal cancer were treated with external beam radiotherapy (45-50.4 Gy) plus IGABT with or without chemotherapy. Distribution of International Federation of Gynecology and Obstetrics stages among patients were as follows: 4 patients had Stage II cancer, 5 patients had Stage III cancer, and 4 patients had Stage IV cancer. The concept of IGABT as developed for cervix cancer was transferred and adapted for vaginal cancer, with corresponding treatment planning and reporting. Doses were converted to the equivalent dose in 2 Gy, applying the linear quadratic model ({alpha}/{beta} = 10 Gy for tumor; {alpha}/{beta} = 3 for organs at risk). Endpoints studied were gross tumor volume (GTV), dose-volume parameters for high-risk clinical target volume (HRCTV), and organs at risk, local control (LC), adverse side effects, and survival. Results: The mean GTV ({+-} 1 standard deviation) at diagnosis was 45.3 ({+-}30) cm{sup 3}, and the mean GTV at brachytherapy was 10 ({+-}14) cm{sup 3}. The mean D90 for the HRCTV was 86 ({+-}13) Gy. The mean D2cc for bladder, urethra, rectum, and sigmoid colon were 80 ({+-}20) Gy, 76 ({+-}16) Gy, 70 ({+-}9) Gy, and 60 ({+-}9) Gy, respectively. After a median follow-up of 43 months (range, 19-87 months), one local recurrence and two distant metastases cases were observed. Actuarial LC and overall survival rates at 3 years were 92% and 85%. One patient with Stage IVA and 1 patient with Stage III disease experienced fistulas (one vesicovaginal, one rectovaginal), and 1 patient developed periurethral necrosis. Conclusions: The concept of IGABT, originally developed for treating cervix cancer, appears to be applicable to vaginal cancer treatment with only minor adaptations. Dose-volume parameters for HRCTV and

  13. Late Cardiac Toxicity After Mediastinal Radiation Therapy for Hodgkin Lymphoma: Contributions of Coronary Artery and Whole Heart Dose-Volume Variables to Risk Prediction.

    Science.gov (United States)

    Hahn, Ezra; Jiang, Haiyan; Ng, Angela; Bashir, Shaheena; Ahmed, Sameera; Tsang, Richard; Sun, Alexander; Gospodarowicz, Mary; Hodgson, David

    2017-08-01

    Mediastinal radiation therapy (RT) for Hodgkin lymphoma (HL) is associated with late cardiotoxicity, but there are limited data to indicate which dosimetric parameters are most valuable for predicting this risk. This study investigated which whole heart dosimetric measurements provide the most information regarding late cardiotoxicity, and whether coronary artery dosimetry was more predictive of this outcome than whole heart dosimetry. A random sample of 125 HL patients treated with mediastinal RT was selected, and 3-dimensional cardiac dose-volume data were generated from historical plans using validated methods. Cardiac events were determined by linking patients to population-based datasets of inpatient and same-day hospitalizations and same-day procedures. Variables collected for the whole heart and 3 coronary arteries included the following: Dmean, Dmax, Dmin, dose homogeneity, V5, V10, V20, and V30. Multivariable competing risk regression models were generated for the whole heart and coronary arteries. There were 44 cardiac events documented, of which 70% were ischemic. The best multivariable model included the following covariates: whole heart Dmean (hazard ratio [HR] 1.09, P=.0083), dose homogeneity (HR 0.94, P=.0034), male sex (HR 2.31, P=.014), and age (HR 1.03, P=.0049). When any adverse cardiac event was the outcome, models using coronary artery variables did not perform better than models using whole heart variables. However, in a subanalysis of ischemic cardiac events only, the model using coronary artery variables was superior to the whole heart model and included the following covariates: age (HR 1.05, P<.001), volume of left anterior descending artery receiving 5 Gy (HR 0.98, P=.003), and volume of left circumflex artery receiving 20 Gy (HR 1.03, P<.001). In addition to higher mean heart dose, increasing inhomogeneity in cardiac dose was associated with a greater risk of late cardiac effects. When all types of cardiotoxicity were evaluated, the

  14. Circumferential or sectored beam arrangements for stereotactic body radiation therapy (SBRT) of primary lung tumors: Effect on target and normal-structure dose-volume metrics

    International Nuclear Information System (INIS)

    Rosenberg, Mara W.; Kato, Catherine M.; Carson, Kelly M.P.; Matsunaga, Nathan M.; Arao, Robert F.; Doss, Emily J.; McCracken, Charles L.; Meng, Lu Z.; Chen, Yiyi; Laub, Wolfram U.; Fuss, Martin; Tanyi, James A.

    2013-01-01

    To compare 2 beam arrangements, sectored (beam entry over ipsilateral hemithorax) vs circumferential (beam entry over both ipsilateral and contralateral lungs), for static-gantry intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) delivery techniques with respect to target and organs-at-risk (OAR) dose-volume metrics, as well as treatment delivery efficiency. Data from 60 consecutive patients treated using stereotactic body radiation therapy (SBRT) for primary non–small-cell lung cancer (NSCLC) formed the basis of this study. Four treatment plans were generated per data set: IMRT/VMAT plans using sectored (-s) and circumferential (-c) configurations. The prescribed dose (PD) was 60 Gy in 5 fractions to 95% of the planning target volume (PTV) (maximum PTV dose ∼ 150% PD) for a 6-MV photon beam. Plan conformality, R 50 (ratio of volume circumscribed by the 50% isodose line and the PTV), and D 2 cm (D max at a distance ≥2 cm beyond the PTV) were evaluated. For lungs, mean doses (mean lung dose [MLD]) and percent V 30 /V 20 /V 10 /V 5 Gy were assessed. Spinal cord and esophagus D max and D 5 /D 50 were computed. Chest wall (CW) D max and absolute V 30 /V 20 /V 10 /V 5 Gy were reported. Sectored SBRT planning resulted in significant decrease in contralateral MLD and V 10 /V 5 Gy , as well as contralateral CW D max and V 10 /V 5 Gy (all p max and D 5 /D 50 for the spinal cord with sectored planning did not reach statistical significance for static-gantry IMRT, although VMAT metrics did show a statistically significant decrease (all p 50 significantly improved with IMRT-s/VMAT-c (p 2 cm significantly improved with VMAT-c (p < 0.001). Plan delivery efficiency improved with sectored technique (p < 0.001); mean monitor unit (MU)/cGy of PD decreased from 5.8 ± 1.9 vs 5.3 ± 1.7 (IMRT) and 2.7 ± 0.4 vs 2.4 ± 0.3 (VMAT). The sectored configuration achieves unambiguous dosimetric advantages over circumferential arrangement in terms

  15. Different concentrations and volumes of p-phenylenediamine in pet. (equivalent doses) are associated with similar patch test outcomes

    DEFF Research Database (Denmark)

    Andersen, Flemming; Hamann, Carsten R; Andersen, Klaus E

    2018-01-01

    BACKGROUND: Concern about causing active sensitization when patch testing is performed with p-phenylenediamine (PPD) 1% pet. has led to a recommendation to use PPD 0.3% pet. as a potentially safer preparation. However, the dose per area of allergen delivered, and hence the risk of active sensitiz...

  16. Critical factors besides treatment dose and duration need to be controlled in Pb toxicity tests in plant cell suspension cultures

    OpenAIRE

    Klaudia Sychta; Janusz Szklarzewicz; Aneta Słomka; Ewa Gregoraszczuk; Elżbieta Kuta

    2017-01-01

    The study was designed to determine the proper conditions for suspension culture of Viola tricolor cells in toxicity studies of Pb at different concentrations (0, 200, 500, 1000, 2000 µM) and exposure times (24, 48, 72 h). By forming insoluble salts with ions from the medium, lead (II) nitrate added to the medium decreased the initial 5.7–5.8 pH of the medium, depending on the Pb salt concentration and light intensity. In alamarBlue assays, we found no dose- or time-dependent effect of Pb...

  17. A Critical Dose of Doxorubicin Is Required to Alter the Gene Expression Profiles in MCF-7 Cells Acquiring Multidrug Resistance

    Science.gov (United States)

    Tsou, Shang-Hsun; Chen, Tzer-Ming; Hsiao, Hui-Ting; Chen, Yen-Hui

    2015-01-01

    Cellular mechanisms of multidrug resistance (MDR) are related to ABC transporters, apoptosis, antioxidation, drug metabolism, DNA repair and cell proliferation. It remains unclear whether the process of resistance development is programmable. We aimed to study gene expression profiling circumstances in MCF-7 during MDR development. Eleven MCF-7 sublines with incremental doxorubicin resistance were established as a valued tool to study resistance progression. MDR marker P-gp was overexpressed only in cells termed MCF-7/ADR-1024 under the selection dose approaching 1024 nM. MCF-7/ADR-1024 and authentic MCF-7/ADR shared common features in cell morphology and DNA ploidy status. MCF-7/ADR-1024 and authentic MCF-7/ADR down regulated repair genes BRCA1/2 and wild type p53, apoptosis-related gene Bcl-2 and epithelial-mesenchymal transition (EMT) epithelial marker gene E-cadherin. While detoxifying enzymes glutathione-S transferase-π and protein kinase C-α were up-regulated. The genes involving in EMT mesenchymal formation were also overexpressed, including N-cadherin, vimentin and the E-cadherin transcription reppressors Slug, Twist and ZEB1/2. PI3K/AKT inhibitor wortmannin suppressed expression of Slug, Twist and mdr1. Mutant p53 with a deletion at codons 127-133 markedly appeared in MCF-7/ADR-1024 and authentic MCF-7/ADR as well. In addition, MCF-7/ADR-1024 cells exerted CSC-like cell surface marker CD44 high/CD24 low and form mammospheres. Overall, results suggest that resistance marker P-gp arises owing to turn on/off or mutation of the genes involved in DNA repair, apoptosis, detoxifying enzymes, EMT and ABC transporters at a turning point (1.024 μM doxorubicin challenge). Behind this point, no obvious alterations were found in most tested genes. Selection for CSC-like cells under this dose may importantly attribute to propagation of the population presenting invasive properties and drug resistance. We thereby suggest two models in the induction of drug resistance

  18. Dose-volume-related dysphagia after constrictor muscles definition in head and neck cancer intensity-modulated radiation treatment.

    Science.gov (United States)

    Mazzola, R; Ricchetti, F; Fiorentino, A; Fersino, S; Giaj Levra, N; Naccarato, S; Sicignano, G; Albanese, S; Di Paola, G; Alterio, D; Ruggieri, R; Alongi, F

    2014-12-01

    Dysphagia remains a side effect influencing the quality of life of patients with head and neck cancer (HNC) after radiotherapy. We evaluated the relationship between planned dose involvement and acute and late dysphagia in patients with HNC treated with intensity-modulated radiation therapy (IMRT), after a recontouring of constrictor muscles (PCs) and the cricopharyngeal muscle (CM). Between December 2011 and December 2013, 56 patients with histologically proven HNC were treated with IMRT or volumetric-modulated arc therapy. The PCs and CM were recontoured. Correlations between acute and late toxicity and dosimetric parameters were evaluated. End points were analysed using univariate logistic regression. An increasing risk to develop acute dysphagia was observed when constraints to the middle PCs were not respected [mean dose (Dmean) ≥50 Gy, maximum dose (Dmax) >60 Gy, V50 >70% with a p = 0.05]. The superior PC was not correlated with acute toxicity but only with late dysphagia. The inferior PC was not correlated with dysphagia; for the CM only, Dmax >60 Gy was correlated with acute dysphagia ≥ grade 2. According to our analysis, the superior PC has a major role, being correlated with dysphagia at 3 and 6 months after treatments; the middle PC maintains this correlation only at 3 months from the beginning of radiotherapy, but it does not have influence on late dysphagia. The inferior PC and CM have a minimum impact on swallowing symptoms. We used recent guidelines to define dose constraints of the PCs and CM. Two results emerge in the present analysis: the superior PC influences late dysphagia, while the middle PC influences acute dysphagia.

  19. Low-dose rapamycin reduces kidney volume angiomyolipomas and prevents the loss of renal function in a patient with tuberous sclerosis complex.

    Science.gov (United States)

    Peces, Ramón; Peces, Carlos; Cuesta-López, Emilio; Pérez-Dueñas, Virginia; Vega-Cabrera, Cristina; Azorín, Sebastián; Selgas, Rafael

    2010-11-01

    Tuberous sclerosis complex (TSC) is caused by constitutively activated mammalian target of rapamycin (mTOR) resulting in non-malignant tumours of several organs including renal angiomyolipomas (AMLs). AMLs may originate renal failure, hypertension and spontaneous life-threatening bleeding. Recent reports suggest a possible beneficial role of the mTOR inhibitor rapamycin for TSC. However, safety and efficiency of rapamycin in TSC patients as an anti-proliferative agent are still undefined. A 40-year-old man with sporadic TSC and a history of spontaneous bleeding from his left kidney AMLs received low-dose rapamycin for 12 months, and this was associated with a reduction in bilateral kidney AML volume, stabilization and even improvement of renal function. There was also a reduction of facial angiofibromas, improvement of blood pressure control and absence of AML bleeding over this time period. Brain lesion images remained stable, and no significant rapamycin-associated side effects were noted. To the best of our knowledge, this is the first report of a case of reduction in renal AML volume together with preservation of renal function in a patient with TSC receiving low-dose rapamycin. These data suggest that it could be the result of the anti-angiogenic, anti-fibrotic and anti-proliferative effects of rapamycin.

  20. Calculation of absorbed doses in sphere volumes around the Mammosite using the Monte Carlo simulation code MCNPX; Calculo de dosis absorbida en volumenes esfericos alrededor del Mammosite utilizando el codigo de simulacion Monte Carlo MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E. L. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico)

    2008-07-01

    The objective of this study is to investigate the changes observed in the absorbed doses in mammary gland tissue when irradiated with a equipment of high dose rate known as Mammosite and introducing material resources contrary to the tissue that constitutes the mammary gland. The modeling study is performed with the code MCNPX, 2005 version, the equipment and the mammary gland and calculating the absorbed doses in tissue when introduced small volumes of air or calcium in the system. (Author)

  1. SU-C-BRA-05: Delineating High-Dose Clinical Target Volumes for Head and Neck Tumors Using Machine Learning Algorithms

    International Nuclear Information System (INIS)

    Cardenas, C; Wong, A; Mohamed, A; Fuller, C; Yang, J; Court, L; Aristophanous, M; Rao, A

    2016-01-01

    Purpose: To develop and test population-based machine learning algorithms for delineating high-dose clinical target volumes (CTVs) in H&N tumors. Automating and standardizing the contouring of CTVs can reduce both physician contouring time and inter-physician variability, which is one of the largest sources of uncertainty in H&N radiotherapy. Methods: Twenty-five node-negative patients treated with definitive radiotherapy were selected (6 right base of tongue, 11 left and 9 right tonsil). All patients had GTV and CTVs manually contoured by an experienced radiation oncologist prior to treatment. This contouring process, which is driven by anatomical, pathological, and patient specific information, typically results in non-uniform margin expansions about the GTV. Therefore, we tested two methods to delineate high-dose CTV given a manually-contoured GTV: (1) regression-support vector machines(SVM) and (2) classification-SVM. These models were trained and tested on each patient group using leave-one-out cross-validation. The volume difference(VD) and Dice similarity coefficient(DSC) between the manual and auto-contoured CTV were calculated to evaluate the results. Distances from GTV-to-CTV were computed about each patient’s GTV and these distances, in addition to distances from GTV to surrounding anatomy in the expansion direction, were utilized in the regression-SVM method. The classification-SVM method used categorical voxel-information (GTV, selected anatomical structures, else) from a 3×3×3cm3 ROI centered about the voxel to classify voxels as CTV. Results: Volumes for the auto-contoured CTVs ranged from 17.1 to 149.1cc and 17.4 to 151.9cc; the average(range) VD between manual and auto-contoured CTV were 0.93 (0.48–1.59) and 1.16(0.48–1.97); while average(range) DSC values were 0.75(0.59–0.88) and 0.74(0.59–0.81) for the regression-SVM and classification-SVM methods, respectively. Conclusion: We developed two novel machine learning methods to delineate

  2. SU-C-BRA-05: Delineating High-Dose Clinical Target Volumes for Head and Neck Tumors Using Machine Learning Algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas, C [Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); The University of Texas Graduate School of Biomedical Sciences, Houston, TX (United States); Wong, A [Department of Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); School of Medicine, The University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States); Mohamed, A; Fuller, C [Department of Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Yang, J; Court, L; Aristophanous, M [Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Rao, A [Department of Bioinformatics and Computational Biology, The University of Texas M.D. Anderson Cancer Center, Houston, TX (United States)

    2016-06-15

    Purpose: To develop and test population-based machine learning algorithms for delineating high-dose clinical target volumes (CTVs) in H&N tumors. Automating and standardizing the contouring of CTVs can reduce both physician contouring time and inter-physician variability, which is one of the largest sources of uncertainty in H&N radiotherapy. Methods: Twenty-five node-negative patients treated with definitive radiotherapy were selected (6 right base of tongue, 11 left and 9 right tonsil). All patients had GTV and CTVs manually contoured by an experienced radiation oncologist prior to treatment. This contouring process, which is driven by anatomical, pathological, and patient specific information, typically results in non-uniform margin expansions about the GTV. Therefore, we tested two methods to delineate high-dose CTV given a manually-contoured GTV: (1) regression-support vector machines(SVM) and (2) classification-SVM. These models were trained and tested on each patient group using leave-one-out cross-validation. The volume difference(VD) and Dice similarity coefficient(DSC) between the manual and auto-contoured CTV were calculated to evaluate the results. Distances from GTV-to-CTV were computed about each patient’s GTV and these distances, in addition to distances from GTV to surrounding anatomy in the expansion direction, were utilized in the regression-SVM method. The classification-SVM method used categorical voxel-information (GTV, selected anatomical structures, else) from a 3×3×3cm3 ROI centered about the voxel to classify voxels as CTV. Results: Volumes for the auto-contoured CTVs ranged from 17.1 to 149.1cc and 17.4 to 151.9cc; the average(range) VD between manual and auto-contoured CTV were 0.93 (0.48–1.59) and 1.16(0.48–1.97); while average(range) DSC values were 0.75(0.59–0.88) and 0.74(0.59–0.81) for the regression-SVM and classification-SVM methods, respectively. Conclusion: We developed two novel machine learning methods to delineate

  3. Low-dose triple-rule-out using 320-row-detector volume MDCT - less contrast medium and lower radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    Durmus, Tahir; Lembcke, Alexander; Muehler, Matthias R.; Hamm, Bernd; Hein, Patrick A. [Charite - University Hospital Berlin, Department of Radiology, Berlin (Germany); Rogalla, Patrik [Universitiy of Toronto, Department of Medical Imaging, Toronto, ON (Canada)

    2011-07-15

    To investigate image quality of triple-rule-out (TRO) computed tomography (CT) using a 320-row-detector CT system with substantially reduced contrast medium volume at 100 kV. Forty-six consecutive patients with noncritical, acute chest pain underwent 320-row-detector CT using a two-step TRO protocol consisting of a non-spiral, non-gated chest CT acquisition (150 mA) followed by a non-spiral, electrocardiography-gated cardiac acquisition (200-500 mA based on body mass index (BMI)). Data were acquired using a biphasic injection protocol with a total iodinated contrast medium volume of 60 ml (370 mg/ml). Vessel attenuation and effective doses were recorded. Image quality was scored independently by two readers. Mean attenuation was 584 {+-} 114 Hounsfield units (HU) in the ascending aorta, 335 {+-} 63HU in the aortic arch, 658 {+-} 136HU in the pulmonary trunk, and 521 {+-} 97HU and 549 {+-} 102HU in the right and left coronary artery, respectively. In all but one patient, attenuation and image quality allowed accurate visualization of the pulmonary arteries, thoracic aorta, and coronary arteries in a single examination. Ninety-six percent of all coronary artery segments were rated diagnostic. Radiation exposure ranged between 2.0 and 3.3 mSv. Using 320-row-detector CT the investigated low-dose TRO protocol resulted in excellent opacification and image quality with substantial reduction of contrast medium volume compared to recently published TRO protocols. (orig.)

  4. Dose-volume histogram comparison between static 5-field IMRT with 18-MV X-rays and helical tomotherapy with 6-MV X-rays.

    Science.gov (United States)

    Hayashi, Akihiro; Shibamoto, Yuta; Hattori, Yukiko; Tamura, Takeshi; Iwabuchi, Michio; Otsuka, Shinya; Sugie, Chikao; Yanagi, Takeshi

    2015-03-01

    We treated prostate cancer patients with static 5-field intensity-modulated radiation therapy (IMRT) using linac 18-MV X-rays or tomotherapy with 6-MV X-rays. As X-ray energies differ, we hypothesized that 18-MV photon IMRT may be better for large patients and tomotherapy may be more suitable for small patients. Thus, we compared dose-volume parameters for the planning target volume (PTV) and organs at risk (OARs) in 59 patients with T1-3 N0M0 prostate cancer who had been treated using 5-field IMRT. For these same patients, tomotherapy plans were also prepared for comparison. In addition, plans of 18 patients who were actually treated with tomotherapy were analyzed. The evaluated parameters were homogeneity indicies and a conformity index for the PTVs, and D2 (dose received by 2% of the PTV in Gy), D98, Dmean and V10-70 Gy (%) for OARs. To evaluate differences by body size, patients with a known body mass index were grouped by that index ( 25 kg/m(2)). For the PTV, all parameters were higher in the tomotherapy plans compared with the 5-field IMRT plans. For the rectum, V10 Gy and V60 Gy were higher, whereas V20 Gy and V30 Gy were lower in the tomotherapy plans. For the bladder, all parameters were higher in the tomotherapy plans. However, both plans were considered clinically acceptable. Similar trends were observed in 18 patients treated with tomotherapy. Obvious trends were not observed for body size. Tomotherapy provides equivalent dose distributions for PTVs and OARs compared with 18-MV 5-field IMRT. Tomotherapy could be used as a substitute for high-energy photon IMRT for prostate cancer regardless of body size. © The Author 2015. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  5. Circumferential or sectored beam arrangements for stereotactic body radiation therapy (SBRT) of primary lung tumors: Effect on target and normal-structure dose-volume metrics

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, Mara W. [Broad Institute of MIT and Harvard, Cambridge, MA (United States); Department of Physics, Brandeis University, Waltham, MA (United States); Kato, Catherine M. [Macalester College, St. Paul, MN (United States); Carson, Kelly M.P. [The University of North Carolina, Chapel Hill, NC (United States); Matsunaga, Nathan M. [Santa Clara University, Santa Clara, CA (United States); Arao, Robert F. [Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland, OR (United States); Doss, Emily J. [Department of Internal Medicine, Providence St. Vincent Medical Center, Portland, OR (United States); McCracken, Charles L. [Department of Radiation Medicine, Oregon Health and Science University, Portland, OR (United States); Meng, Lu Z. [Department of Radiation Oncology, University of California Davis Comprehensive Cancer Center, Sacramento, CA (United States); Chen, Yiyi [Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland, OR (United States); Laub, Wolfram U.; Fuss, Martin [Department of Radiation Medicine, Oregon Health and Science University, Portland, OR (United States); Department of Nuclear Engineering and Radiation Health Physics, Oregon State University, Corvallis, OR (United States); Tanyi, James A., E-mail: tanyij@ohsu.edu [Department of Radiation Medicine, Oregon Health and Science University, Portland, OR (United States); Department of Nuclear Engineering and Radiation Health Physics, Oregon State University, Corvallis, OR (United States)

    2013-01-01

    To compare 2 beam arrangements, sectored (beam entry over ipsilateral hemithorax) vs circumferential (beam entry over both ipsilateral and contralateral lungs), for static-gantry intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) delivery techniques with respect to target and organs-at-risk (OAR) dose-volume metrics, as well as treatment delivery efficiency. Data from 60 consecutive patients treated using stereotactic body radiation therapy (SBRT) for primary non–small-cell lung cancer (NSCLC) formed the basis of this study. Four treatment plans were generated per data set: IMRT/VMAT plans using sectored (-s) and circumferential (-c) configurations. The prescribed dose (PD) was 60 Gy in 5 fractions to 95% of the planning target volume (PTV) (maximum PTV dose ∼ 150% PD) for a 6-MV photon beam. Plan conformality, R{sub 50} (ratio of volume circumscribed by the 50% isodose line and the PTV), and D{sub 2} {sub cm} (D{sub max} at a distance ≥2 cm beyond the PTV) were evaluated. For lungs, mean doses (mean lung dose [MLD]) and percent V{sub 30}/V{sub 20}/V{sub 10}/V{sub 5} Gy were assessed. Spinal cord and esophagus D{sub max} and D{sub 5}/D{sub 50} were computed. Chest wall (CW) D{sub max} and absolute V{sub 30}/V{sub 20}/V{sub 10}/V{sub 5} {sub Gy} were reported. Sectored SBRT planning resulted in significant decrease in contralateral MLD and V{sub 10}/V{sub 5} {sub Gy}, as well as contralateral CW D{sub max} and V{sub 10}/V{sub 5} {sub Gy} (all p < 0.001). Nominal reductions of D{sub max} and D{sub 5}/D{sub 50} for the spinal cord with sectored planning did not reach statistical significance for static-gantry IMRT, although VMAT metrics did show a statistically significant decrease (all p < 0.001). The respective measures for esophageal doses were significantly lower with sectored planning (p < 0.001). Despite comparable dose conformality, irrespective of planning configuration, R{sub 50} significantly improved with IMRT

  6. Effect of contrast dose in the quantification of myocardial extra-cellular volume in adenosine stress/rest perfusion cardiac magnetic resonance examinations.

    Science.gov (United States)

    Caballeros, Meylin; Bartolomé, Pablo; Fernández González, Óscar; Greiser, Andreas; García Del Barrio, Loreto; Pueyo, Jesús; Bastarrika, Gorka

    2017-07-01

    Background Diffuse myocardial fibrosis can be quantified by calculating extra-cellular volume (ECV) from native and post-contrast T1 values using dedicated single bolus contrast medium injection protocols. Purpose To evaluate differences in T1 maps and myocardial ECV measurements in routine stress/rest perfusion cardiovascular magnetic resonance (CMR) examinations after injection of single and double dose of contrast medium. Material and Methods Thirty-seven consecutive patients (30 men; mean age, 62 ± 13 years) underwent clinically indicated adenosine stress/rest perfusion CMR examination to rule out myocardial ischemia following a conventional split-dose contrast medium injection strategy. Native and post-contrast T1 mapping was performed 15 min after the first (0.1 mmol/kg) and second (0.1 mmol/kg) dose of contrast medium using a breath-held Modified Look-Locker Inversion recovery (MOLLI) sequence. Student's t-test for paired samples, Bland-Altman plots, and concordance-correlation coefficients (CCC) for agreement between T1 and ECV calculations after single and double dose of contrast medium were calculated. Intra- and inter-observer agreement for measurements was also analyzed. Results Myocardial T1 values after single and double dose of contrast medium significantly differed (mean difference of 114.1 ± 19.9 ms, P < 0.01). A single dose of contrast agent provided slightly higher ECV values (mean difference of 2.3 ± 1.1%). CCC for ECV calculations was 0.66. Intra- and inter-observer agreement for all measurements was excellent (CCC ≥ 0.83). Conclusion Quantification of myocardial ECV on conventional stress/rest perfusion CMR examination is feasible. T1 maps obtained 15 min after 0.1 mmol/kg of contrast medium provide slightly higher myocardial T1 measurements and ECV values compared with T1 maps obtained after a total dose of 0.2 mmol/kg.

  7. Failure modes and effects analysis in image-guided high-dose-rate brachytherapy: Quality control optimization to reduce errors in treatment volume.

    Science.gov (United States)

    Wadi-Ramahi, Shada; Alnajjar, Waleed; Mahmood, Rana; Jastaniyah, Noha; Moftah, Belal

    2016-01-01

    Analyze the inputs which cause treatment to the wrong volume in high-dose-rate brachytherapy (HDRB), with emphasis on imaging role during implant, planning, and treatment verification. The end purpose is to compare our current practice to the findings of the study and apply changes where necessary. Failure mode and effects analysis was used to study the failure pathways for treating the wrong volume in HDRB. The role of imaging and personnel was emphasized, and subcategories were formed. A quality assurance procedure is proposed for each high-scoring failure mode (FM). Forty FMs were found that lead to treating the wrong volume. Of these, 73% were human failures, 20% were machine failures, and 7% were procedural/guideline failures. The use of imaging was found to resolve 85% of the FMs. We also noted that imaging processes were under used in current practice of HDRB especially in pretreatment verification. Twelve FMs (30%) scored the highest, and for each one of them, we propose clinical/practical solutions that could be applied to reduce the risk by increasing detectability. This work resulted in two conclusions: the role of imaging in improving failure detection and the emphasized role of human-based failures. The majority of FMs are human failures, and imaging increased the ability to detect 85% of all FMs. We proposed quality assurance practices for each high-scoring FM and have implemented some of them in our own practice. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  8. Radiation Therapy for Cutaneous Squamous Cell Carcinoma Involving the Parotid Area Lymph Nodes: Dose and Volume Considerations

    International Nuclear Information System (INIS)

    Chen, Allen M.; Grekin, Roy C.; Garcia, Joaquin; Bucci, Mary K.; Margolis, Lawrence W.

    2007-01-01

    Purpose: The intraparotid and periparotid lymph nodes are the most commonly involved when skin cancer of the head and neck metastasizes beyond the primary site. We sought to report the clinical outcome of patients treated with radiation therapy for parotid-area metastases from cutaneous squamous cell carcinoma of the head and neck. Methods and Materials: The records of 36 patients treated with radiation therapy for cutaneous squamous cell carcinoma involving the parotid-area lymph nodes were reviewed. All patients had clinically N0 necks and were without evidence of distant disease. Thirty patients (83%) were treated postoperatively after gross total tumor resection. Median dose to the parotid area was 60 Gy (range, 50-72 Gy). Treatment of clinically N0 necks consisted of surgical dissection (7 patients), irradiation (15 patients), and observation (14 patients). Results: The 5-year estimate of local (parotid) control was 86% in patients treated using surgery with postoperative therapy and 47% in patients treated using radiation therapy alone. Three of 4 patients with tumors that relapsed locally after surgery and postoperative radiation received a dose of less than 60 Gy. Elective neck irradiation decreased the incidence of subsequent nodal failures from 50% to 0% and significantly improved neck control (p < 0.001). The 5-year overall survival rate was 63%. Conclusions: Surgery followed by radiation therapy to doses of at least 60 Gy results in effective local control for patients with parotid area metastasis from cutaneous squamous cell carcinoma. Routine irradiation of the clinically N0 neck is recommended

  9. Syringe shape and positioning relative to efficiency volume inside dose calibrators and its role in nuclear medicine quality assurance programs

    Energy Technology Data Exchange (ETDEWEB)

    Santos, J.A.M. [Servico de Fisica Medica, Instituto Portugues de Oncologia do Porto Francisco Gentil, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200072 Porto (Portugal); Centro de Investigacao, Instituto Portugues de Oncologia do Porto Francisco Gentil, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200072 Porto (Portugal)], E-mail: a.miranda@portugalmail.pt; Carrasco, M.F. [Servico de Fisica Medica, Instituto Portugues de Oncologia do Porto Francisco Gentil, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200072 Porto (Portugal); Centro de Investigacao, Instituto Portugues de Oncologia do Porto Francisco Gentil, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200072 Porto (Portugal); Lencart, J. [Servico de Fisica Medica, Instituto Portugues de Oncologia do Porto Francisco Gentil, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200072 Porto (Portugal); Bastos, A.L. [Servico de Medicina Nuclear, Instituto Portugues de Oncologia do Porto Francisco Gentil, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200072 Porto (Portugal)

    2009-06-15

    A careful analysis of geometry and source positioning influence in the activity measurement outcome of a nuclear medicine dose calibrator is presented for {sup 99m}Tc. The implementation of a quasi-point source apparent activity curve measurement is proposed for an accurate correction of the activity inside several syringes, and compared with a theoretical geometric efficiency model. Additionally, new geometrical parameters are proposed to test and verify the correct positioning of the syringes as part of acceptance testing and quality control procedures.

  10. A critical review and database of biomass and volume allometric equation for trees and shrubs of Bangladesh

    Science.gov (United States)

    Mahmood, H.; Siddique, M. R. H.; Akhter, M.

    2016-08-01

    Estimations of biomass, volume and carbon stock are important in the decision making process for the sustainable management of a forest. These estimations can be conducted by using available allometric equations of biomass and volume. Present study aims to: i. develop a compilation with verified allometric equations of biomass, volume, and carbon for trees and shrubs of Bangladesh, ii. find out the gaps and scope for further development of allometric equations for different trees and shrubs of Bangladesh. Key stakeholders (government departments, research organizations, academic institutions, and potential individual researchers) were identified considering their involvement in use and development of allometric equations. A list of documents containing allometric equations was prepared from secondary sources. The documents were collected, examined, and sorted to avoid repetition, yielding 50 documents. These equations were tested through a quality control scheme involving operational verification, conceptual verification, applicability, and statistical credibility. A total of 517 allometric equations for 80 species of trees, shrubs, palm, and bamboo were recorded. In addition, 222 allometric equations for 39 species were validated through the quality control scheme. Among the verified equations, 20%, 12% and 62% of equations were for green-biomass, oven-dried biomass, and volume respectively and 4 tree species contributed 37% of the total verified equations. Five gaps have been pinpointed for the existing allometric equations of Bangladesh: a. little work on allometric equation of common tree and shrub species, b. most of the works were concentrated on certain species, c. very little proportion of allometric equations for biomass estimation, d. no allometric equation for belowground biomass and carbon estimation, and d. lower proportion of valid allometric equations. It is recommended that site and species specific allometric equations should be developed and

  11. Therapeutic analysis of high-dose-rate {sup 192}Ir vaginal cuff brachytherapy for endometrial cancer using a cylindrical target volume model and varied cancer cell distributions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hualin, E-mail: hualin.zhang@northwestern.edu; Donnelly, Eric D.; Strauss, Jonathan B. [Department of Radiation Oncology, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, Illinois 60611 (United States); Qi, Yujin [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2016-01-15

    Purpose: To evaluate high-dose-rate (HDR) vaginal cuff brachytherapy (VCBT) in the treatment of endometrial cancer in a cylindrical target volume with either a varied or a constant cancer cell distributions using the linear quadratic (LQ) model. Methods: A Monte Carlo (MC) technique was used to calculate the 3D dose distribution of HDR VCBT over a variety of cylinder diameters and treatment lengths. A treatment planning system (TPS) was used to make plans for the various cylinder diameters, treatment lengths, and prescriptions using the clinical protocol. The dwell times obtained from the TPS were fed into MC. The LQ model was used to evaluate the therapeutic outcome of two brachytherapy regimens prescribed either at 0.5 cm depth (5.5 Gy × 4 fractions) or at the vaginal mucosal surface (8.8 Gy × 4 fractions) for the treatment of endometrial cancer. An experimentally determined endometrial cancer cell distribution, which showed a varied and resembled a half-Gaussian distribution, was used in radiobiology modeling. The equivalent uniform dose (EUD) to cancer cells was calculated for each treatment scenario. The therapeutic ratio (TR) was defined by comparing VCBT with a uniform dose radiotherapy plan in term of normal cell survival at the same level of cancer cell killing. Calculations of clinical impact were run twice assuming two different types of cancer cell density distributions in the cylindrical target volume: (1) a half-Gaussian or (2) a uniform distribution. Results: EUDs were weakly dependent on cylinder size, treatment length, and the prescription depth, but strongly dependent on the cancer cell distribution. TRs were strongly dependent on the cylinder size, treatment length, types of the cancer cell distributions, and the sensitivity of normal tissue. With a half-Gaussian distribution of cancer cells which populated at the vaginal mucosa the most, the EUDs were between 6.9 Gy × 4 and 7.8 Gy × 4, the TRs were in the range from (5.0){sup 4} to (13

  12. Therapeutic analysis of high-dose-rate 192Ir vaginal cuff brachytherapy for endometrial cancer using a cylindrical target volume model and varied cancer cell distributions

    Science.gov (United States)

    Zhang, Hualin; Donnelly, Eric D.; Strauss, Jonathan B.; Qi, Yujin

    2016-01-01

    Purpose: To evaluate high-dose-rate (HDR) vaginal cuff brachytherapy (VCBT) in the treatment of endometrial cancer in a cylindrical target volume with either a varied or a constant cancer cell distributions using the linear quadratic (LQ) model. Methods: A Monte Carlo (MC) technique was used to calculate the 3D dose distribution of HDR VCBT over a variety of cylinder diameters and treatment lengths. A treatment planning system (TPS) was used to make plans for the various cylinder diameters, treatment lengths, and prescriptions using the clinical protocol. The dwell times obtained from the TPS were fed into MC. The LQ model was used to evaluate the therapeutic outcome of two brachytherapy regimens prescribed either at 0.5 cm depth (5.5 Gy × 4 fractions) or at the vaginal mucosal surface (8.8 Gy × 4 fractions) for the treatment of endometrial cancer. An experimentally determined endometrial cancer cell distribution, which showed a varied and resembled a half-Gaussian distribution, was used in radiobiology modeling. The equivalent uniform dose (EUD) to cancer cells was calculated for each treatment scenario. The therapeutic ratio (TR) was defined by comparing VCBT with a uniform dose radiotherapy plan in term of normal cell survival at the same level of cancer cell killing. Calculations of clinical impact were run twice assuming two different types of cancer cell density distributions in the cylindrical target volume: (1) a half-Gaussian or (2) a uniform distribution. Results: EUDs were weakly dependent on cylinder size, treatment length, and the prescription depth, but strongly dependent on the cancer cell distribution. TRs were strongly dependent on the cylinder size, treatment length, types of the cancer cell distributions, and the sensitivity of normal tissue. With a half-Gaussian distribution of cancer cells which populated at the vaginal mucosa the most, the EUDs were between 6.9 Gy × 4 and 7.8 Gy × 4, the TRs were in the range from (5.0)4 to (13.4)4 for the

  13. Therapeutic analysis of high-dose-rate (192)Ir vaginal cuff brachytherapy for endometrial cancer using a cylindrical target volume model and varied cancer cell distributions.

    Science.gov (United States)

    Zhang, Hualin; Donnelly, Eric D; Strauss, Jonathan B; Qi, Yujin

    2016-01-01

    To evaluate high-dose-rate (HDR) vaginal cuff brachytherapy (VCBT) in the treatment of endometrial cancer in a cylindrical target volume with either a varied or a constant cancer cell distributions using the linear quadratic (LQ) model. A Monte Carlo (MC) technique was used to calculate the 3D dose distribution of HDR VCBT over a variety of cylinder diameters and treatment lengths. A treatment planning system (TPS) was used to make plans for the various cylinder diameters, treatment lengths, and prescriptions using the clinical protocol. The dwell times obtained from the TPS were fed into MC. The LQ model was used to evaluate the therapeutic outcome of two brachytherapy regimens prescribed either at 0.5 cm depth (5.5 Gy × 4 fractions) or at the vaginal mucosal surface (8.8 Gy × 4 fractions) for the treatment of endometrial cancer. An experimentally determined endometrial cancer cell distribution, which showed a varied and resembled a half-Gaussian distribution, was used in radiobiology modeling. The equivalent uniform dose (EUD) to cancer cells was calculated for each treatment scenario. The therapeutic ratio (TR) was defined by comparing VCBT with a uniform dose radiotherapy plan in term of normal cell survival at the same level of cancer cell killing. Calculations of clinical impact were run twice assuming two different types of cancer cell density distributions in the cylindrical target volume: (1) a half-Gaussian or (2) a uniform distribution. EUDs were weakly dependent on cylinder size, treatment length, and the prescription depth, but strongly dependent on the cancer cell distribution. TRs were strongly dependent on the cylinder size, treatment length, types of the cancer cell distributions, and the sensitivity of normal tissue. With a half-Gaussian distribution of cancer cells which populated at the vaginal mucosa the most, the EUDs were between 6.9 Gy × 4 and 7.8 Gy × 4, the TRs were in the range from (5.0)(4) to (13.4)(4) for the radiosensitive normal

  14. SU-F-E-03: PET/CT Guided Dose Boost to Hypoxic Sub-Volume in Nasopharyngeal Carcinomas Using Self-Optimizing Non-Uniform VMAT

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, J; Zheng, X; Liu, H; Chen, B; Zhuo, W [FuDan University HuaDong Hospital, Institute of Radiation Medicine Fudan University Shanghai, Shanghai (China)

    2016-06-15

    Purpose: This study is to evaluate the feasibility of simultaneously integrated boost (SIB) to hypoxic subvolume (HTV) in nasopharyngeal carcinomas under the guidance of 18F-Fluoromisonidazole (FMISO) PET/CT using a novel non-uniform volumetric modulated arc therapy (VMAT)technique. Methods: Eight nasopharyngeal carcinoma patients treated with conventional uniform VMAT were retrospectively analyzed. For each treatment, actual conventional uniform VMAT plan with two or more arcs (2–2.5 arcs, totally rotating angle < 1000o) was designed with dose boost to hopxic subvolume (total dose, 84Gy) in the gross tumor volme (GTV) under the guidance of 18F- FMISO PET/CT. Based on the same dataset, experimental single arc non-uniform VAMT plans were generated with the same dose prescription using customized software tools. Dosimetric parameters, quality assurance and the efficiency of the treatment delivery were compared between the uniform and non-uniform VMAT plans. Results: To develop the non-uniform VMAT technique, a specific optimization model was successfully established. Both techniques generate high-quality plans with pass rate (>98%) with the 3mm, 3% criterion. HTV received dose of 84.1±0.75Gy and 84.1±1.2Gy from uniform and non-uniform VMAT plans, respectively. In terms of target coverage and dose homogeneity, there was no significant statistical difference between actual and experimental plans for each case. However, for critical organs at risk (OAR), including the parotids, oral cavity and larynx, dosimetric difference was significant with better dose sparing form experimental plans. Regarding plan implementation efficiency, the average machine time was 3.5 minutes for the actual VMAT plans and 3.7 minutes for the experimental nonuniform VMAT plans (p>0.050). Conclusion: Compared to conventional VMAT technique, the proposed non-uniform VMAT technique has the potential to produce efficient and safe treatment plans, especially in cases with complicated anatomical

  15. High dose teriparatide (rPTH1-34 therapy increases callus volume and enhances radiographic healing at 8-weeks in a massive canine femoral allograft model.

    Directory of Open Access Journals (Sweden)

    Kohei Nishitani

    Full Text Available Small animal studies have demonstrated significant high-dose recombinant parathyroid hormone1-34 (rPTH1-34 effects on intercalary allograft healing. Towards a human adjuvant therapy to decrease non-unions, we evaluated rPTH1-34 safety and efficacy in a clinically relevant canine femoral allograft model. Adult female mongrel hounds (n = 20 received a 5cm mid-diaphyseal osteotomy reconstructed with a plated allograft, and were randomized to: 1 Placebo (n = 5; daily saline, 2 Continuous rPTH1-34 (n = 7; 5 μg/kg/day s.c. from day 1-55 post-op, or 3 Delayed rPTH1-34 (n = 8; 5 μg/kg/day s.c. from day 14-28 post-op. Safety was assessed by physical behavior and blood calcium monitoring. Cone beam CT (CB-CT was performed on days 14, 28 and 56 post-op to assess 2D cortical healing, 3D bone volume, and Union Ratio. Biomechanical testing and dynamic histomorphometry were also performed. The high drug dose was poorly tolerated, as most dogs receiving rPTH1-34 had to be given intravenous saline, and one dog died from hypercalcemia. Continuous rPTH1-34 significantly increased 2D healing and callus volumes at 4-weeks versus Placebo, and sustained the significant increase in cortical union at 8-week (p<0.05. These rPTH1-34 effects were confirmed by histomorphometry, revealing significant increases in mineral apposition rates (MAR on host bone and graft-host junctions (p<0.05. Delayed rPTH1-34 significantly increased callus volume and MAR at 8 weeks (p<0.05. Although no biomechanical differences were observed, as expected for early healing, the results demonstrated that 2D RUST scoring significantly correlated with torsional biomechanics (p<0.01. In conclusion, 8-weeks of intermittent high-dose rPTH1-34 treatment significantly increases callus formation and accelerates bony union of intercalary massive allografts in a clinically relevant canine model, but with serious side-effects from hypercalcemia.

  16. Developing the Adult Male ICRP Phantom and Evaluation the Absorbed Dose Received By Critical Organs in Head and Neck Region during the Radiotherapy of Eye Cancer

    Directory of Open Access Journals (Sweden)

    Alireza Vejdani-Noghreiyan

    2016-09-01

    Full Text Available Introduction Accurate estimation of the absorbed dose in radiosensitive organs, located away from the target volume during radiotherapy, is one of the main reasons for the development of reference phantoms. The International Commission on Radiological Protection (ICRP reference phantoms can provide a more realistic view of the human anatomy in comparison with the previously used mathematical phantoms. However, the ICRP reference phantoms seem to have certain limitations, resulting in the inaccurate eye simulation due to the absence of super-high-resolution CT scan images. Materials and Methods In this study, we developed a modified version of the ICRP reference phantom by inserting a realistic eye phantom into the voxelized phantom. In addition, by using the developed model, the absorbed dose received by sensitive organs (e.g., thyroid, brain, and different parts of the eye during radiotherapy of a common ocular surface tumor was determined. The results were compared with those obtained by the modified phantom developed by the University of Florida-Oak Ridge National Laboratory (UF-ORNL. Results Based on the results, the relative difference between the equivalent doses calculated by the developed phantom and UF-ORNL phantom was nearly 75-95% and 3% for thyroid and eye substructures, respectively. Conclusion Despite of many advantageous of voxel phantoms, they have considerable limitation in providing accurate model of the eye. In the present study, a detailed stylized model was developed and incorporated into the Adult Male (AM reference and UF-ORNL phantoms. These phantoms were then used for the dosimetric calculations during eyelid cancer therapy.

  17. SU-E-T-289: Dose-Volume-Effect Relationships for Lung Cancer Patients Treated with SBRT On a Prospective Protocol

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    Mayyas, E; Brown, S; Liu, J; Kim, J; Sun, Z; Devpura, S; Ajlouni, M; Siddiqui, F; Movsas, B; Chetty, I [Henry Ford Hospital, Detroit, MI (United States)

    2015-06-15

    Purpose: Stereotactic body radiotherapy (SBRT) is commonly used to treat early stage lung tumors. This study was designed to evaluate associations between dose, volume and clinical outcomes including analysis of both clinical toxicity scores and quality of life (QOL) data for non-small cell lung cancer patients treated with SBRT. Preliminary results are presented. Methods: Sixty-seven NSCLC patients, 46 primarily with early stage, and 21 with recurrent disease were treated with dose regimens consisting mainly of 12 Gy x 4 fractions, and 3 or 5 fractions at lower dose, for patients with recurrent disease (Table 1). Follow-up data is being collected at baseline, after treatment and at 3, 6, 12, 18 and 24 months post-treatment. Clinical follow-up data acquired to date was assessed using the Charlson Comorbidity Clinical and Toxicity Scoring forms. QOL data was evaluated using the EQ-5D, and FACT-TOI validated surveys. All outcomes surveys are collected within an “in-house” developed outcomes database. Results: The median follow-up was 3.5±0.8 months. Mean lung doses (MLD) were converted to BED-2 Gy using the linear-quadratic model with an alpha/beta=3.0. Average MLD was 3.7+3.1 Gy (range: 0.4–20.9 Gy). The percentages of patients with > grade 2 cough, dyspnea and fatigue were 13.3, 17.0, 6.3%, respectively. Preliminary analyses (at 3 months after SBRT) show a mild correlation between MLD > 2 Gy and > grade 2 cough (borderline significant) and dyspnea (significant, p<0.05). One patient was observed with a grade 3 cough. Given the short follow-up, tumor control is not yet assessable. Conclusion: The SBRT dose fractionation regimen of 12 Gy x 4 was well tolerated at early time points. Additional follow-up is required to assess the long-term clinical outcome efficacy and toxicity profiles of the dose regimen.

  18. SU-E-T-289: Dose-Volume-Effect Relationships for Lung Cancer Patients Treated with SBRT On a Prospective Protocol

    International Nuclear Information System (INIS)

    Mayyas, E; Brown, S; Liu, J; Kim, J; Sun, Z; Devpura, S; Ajlouni, M; Siddiqui, F; Movsas, B; Chetty, I

    2015-01-01

    Purpose: Stereotactic body radiotherapy (SBRT) is commonly used to treat early stage lung tumors. This study was designed to evaluate associations between dose, volume and clinical outcomes including analysis of both clinical toxicity scores and quality of life (QOL) data for non-small cell lung cancer patients treated with SBRT. Preliminary results are presented. Methods: Sixty-seven NSCLC patients, 46 primarily with early stage, and 21 with recurrent disease were treated with dose regimens consisting mainly of 12 Gy x 4 fractions, and 3 or 5 fractions at lower dose, for patients with recurrent disease (Table 1). Follow-up data is being collected at baseline, after treatment and at 3, 6, 12, 18 and 24 months post-treatment. Clinical follow-up data acquired to date was assessed using the Charlson Comorbidity Clinical and Toxicity Scoring forms. QOL data was evaluated using the EQ-5D, and FACT-TOI validated surveys. All outcomes surveys are collected within an “in-house” developed outcomes database. Results: The median follow-up was 3.5±0.8 months. Mean lung doses (MLD) were converted to BED-2 Gy using the linear-quadratic model with an alpha/beta=3.0. Average MLD was 3.7+3.1 Gy (range: 0.4–20.9 Gy). The percentages of patients with > grade 2 cough, dyspnea and fatigue were 13.3, 17.0, 6.3%, respectively. Preliminary analyses (at 3 months after SBRT) show a mild correlation between MLD > 2 Gy and > grade 2 cough (borderline significant) and dyspnea (significant, p<0.05). One patient was observed with a grade 3 cough. Given the short follow-up, tumor control is not yet assessable. Conclusion: The SBRT dose fractionation regimen of 12 Gy x 4 was well tolerated at early time points. Additional follow-up is required to assess the long-term clinical outcome efficacy and toxicity profiles of the dose regimen

  19. Mirrors of the Mind: Introduction to Mindful Ways of Thinking Education. Educational Psychology: Critical Pedagogical Perspectives. Volume 19

    Science.gov (United States)

    Inoue, Noriyuki

    2012-01-01

    "Mirrors of the Mind" uses East Asian epistemology and cultural concepts as new conceptual tools to address fundamental questions that educators encounter. The book invites readers to critically reflect on commonly held assumptions about learning, cognition, motivation, development, and other essential areas of educational psychology and learning…

  20. Acute small-bowel toxicity during neoadjuvant combined radiochemotherapy in locally advanced rectal cancer: determination of optimal dose-volume cut-off value predicting grade 2-3 diarrhoea.

    Science.gov (United States)

    Reis, Tina; Khazzaka, Edwin; Welzel, Grit; Wenz, Frederik; Hofheinz, Ralf-Dieter; Mai, Sabine

    2015-01-31

    Current therapeutic standard for locally advanced rectal cancer is the neoadjuvant radiochemotherapy with total mesorectal excision. Diarrhoea is the main acute side effect, induced by the dose to the small-bowel, frequently leading to a treatment modification. Aim of this study was to analyse the differences between the irradiated small-bowel volumes and the occurrence of acute diarrhea during combined radiochemotherapy for rectal cancer. 45 patients treated with a neoadjuvant radiochemotherapy (three-field box 50.4 Gy; Cetuximab, Capecitabine, Irinotecan) for locally advanced rectal cancer within a prospective phase I/II study were evaluated. Based on the dose-volume histograms, the small-bowel volumes receiving doses of 5, 10 … 45 Gy (V5, V10 …V45) were calculated and compared with the prospectively documented small- bowel toxicities. There was a statistically significant difference between irradiated small-bowel volumes and the severity of therapy related diarrhoea. The strongest validity concerning the risk of developing a grade 2-3 diarrhoea was seen at a dose level of 5 Gy (V 5) with a small-bowel volume of 291.94 cc. Patients with V 5 > 291.94 cc had significantly more often grade 2-3 diarrhoea, than patients with V5 below this cut-off value (82% vs. 29%; p bowel volume receiving 5 Gy should be limited to about 300 cc.

  1. The analysis of correlation between changes of myocardial enzymes level in serum before and after radiation and dose-volume histogram parameters of the heart

    International Nuclear Information System (INIS)

    Ding Xiuping; Li Hongjun; Li Baosheng; Wang Dongqing

    2012-01-01

    Objective: To analyze the correlation between the changes of myocardial enzyme level in serum before and after radiotherapy and dose - volume histogram (DVH) parameters of the heart. Methods: A total of 102 patients with 68 cases of lung cancer and 34 cases of esophageal cancer were recruited. All patients received three-dimensional conformal radiotherapy (3DCRT) or intensity-modulated radiotherapy (IMRT), with the radiation beams passing through the heart. Aspartate aminotransferase (AST), creatine kinase (CK), creatine kinase isozyme (CK-MB), lactate dehydrogenase (LDH), α-hydroxybutyrate dehydrogenase (α-HBDH) were determined in the serum before and after radiotherapy. All the enzyme levels before and after radiotherapy were compared through paired t-test. Independent sample t-test was conducted between sub-groups. And the dose-volume histogram (DVH) parameters of the heart were calculated (the volume percentage of heart receiving dose equal to or exceeding x Gy (V x ). The correlation between myocardial enzyme level and DVH parameters was analyzed through Pearson method. Results: Serum AST, CK-MB, LDH, α-HBDH levels increased significantly after radiotherapy (19.42: 27.89, 14.72:19.57, 178.80 : 217.57, 140.32 : 176.25, t =-3.39 - -6.92, all P=0.000). In Group IMRT, significant correlations between the increase of myocardial enzyme concentration and DVH parameters of the heart are found, AST with V 20 , V 25 , V 30 of heart ( r=0.302 - 0.431, P =0.039 - 0.003), CK with V 30 of heart (r=0.345, P=0.013), and CK-MB, LDH, α-HBDH with V 25 , V 30 (r=0.465 -0.3