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Sample records for boost intensity modulated

  1. Radiochemoimmunotherapy with intensity-modulated concomitant boost: interim analysis of the REACH trial

    OpenAIRE

    Jensen Alexandra D; Krauss Jürgen; Potthoff Karin; Simon Christian; Nikoghosyan Anna V; Lossner Karen; Debus Jürgen; Münter Marc W

    2012-01-01

    Abstract Purpose To evaluate efficacy and toxicity clinical in the intensified treatment of locally advanced squamous cell carcinoma of the head and neck (SCCHN) with the combination of chemotherapy, the EGFR antibody cetuximab, and intensity-modulated radiation therapy (IMRT) in a concomitant boost concept. Methods REACH is a prospective, bi-centric phase II trial of carboplatin/5-FU and cetuximab weekly combined with IMRT. Primary endpoint is locoregional control, secondary endpoints includ...

  2. Ballistic optimisation with intensity modulation with integration of a concomitant boost for the radiotherapy of glioblastomas

    International Nuclear Information System (INIS)

    The authors report a study aimed at the optimisation of the ballistics of intensity-modulated conformation radiotherapy (IMRT) treatment with a boost for the preparation of a multi-centric prospective trial financed by a program on glioblastoma treatment. This treatment consists in using the boost technique to obtain an increase of the dose delivered by the IMRT in sites presenting a strong predictive value for relapse. These sites are defined by means of magnetic resonance spectrometric imagery. Conformation indexes, planning target volumes, doses delivered to organs at risk are analysed. The proximity of organs at risk was the main difficulty, but a good dosimetry has been obtained with the use of five coplanar beams. Short communication

  3. Disease Control and Ototoxicity Using Intensity-Modulated Radiation Therapy Tumor-Bed Boost for Medulloblastoma

    International Nuclear Information System (INIS)

    Purpose: We previously reported excellent local control for treating medulloblastoma with a limited boost to the tumor bed. In order to decrease ototoxicity, we subsequently implemented a tumor-bed boost using intensity-modulated radiation therapy (IMRT), the clinical results of which we report here. Patients and Methods: A total of 33 patients with newly diagnosed medulloblastoma, 25 with standard risk, and 8 with high risk, were treated on an IMRT tumor-bed boost following craniospinal irradiation (CSI). Six standard-risk patients were treated with an institutional protocol with 18 Gy CSI in conjunction with intrathecal iodine-131-labeled monoclonal antibody. The majority of patients received concurrent vincristine and standard adjuvant chemotherapy. Pure-tone audiograms were graded according to National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0. Results: Median age was 9 years old (range, 4-46 years old). Median follow-up was 63 months. Kaplan-Meier estimates of progression-free survival (PFS) and overall survival (OS) rates for standard-risk patients who received 23.4 or 36 Gy CSI (not including those who received 18 Gy CSI with radioimmunotherapy) were 81.4% and 88.4%, respectively, at 5 years; 5-year PFS and OS rates for high-risk patients were both 87.5%. There were no isolated posterior fossa failures outside of the boost volume. Posttreatment audiograms were available for 31 patients, of whom 6%, at a median follow-up of 19 months, had developed Grade 3 hearing loss. Conclusion: An IMRT tumor-bed boost results in excellent local control while delivering a low mean dose to the cochlea, resulting in a low rate of ototoxicity.

  4. Whole breast and excision cavity radiotherapy plan comparison: Conformal radiotherapy with sequential boost versus intensity-modulated radiation therapy with a simultaneously integrated boost

    OpenAIRE

    Small, Katherine; Kelly, Chris; Beldham-Collins, Rachael; Gebski, Val

    2013-01-01

    Introduction A comparative study was conducted comparing the difference between (1) conformal radiotherapy (CRT) to the whole breast with sequential boost excision cavity plans and (2) intensity-modulated radiation therapy (IMRT) to the whole breast with simultaneously integrated boost to the excision cavity. The computed tomography (CT) data sets of 25 breast cancer patients were used and the results analysed to determine if either planning method produced superior plans. Methods CT data set...

  5. Hypofractionated Concomitant Intensity-Modulated Radiotherapy Boost for High-Risk Prostate Cancer: Late Toxicity

    International Nuclear Information System (INIS)

    Purpose: To report the acute and late toxicities of patients with high-risk localized prostate cancer treated using a concomitant hypofractionated, intensity-modulated radiotherapy boost combined with long-term androgen deprivation therapy. Methods and Materials: A prospective Phase I-II study of patients with any of the following: clinical Stage T3 disease, prostate-specific antigen level ≥20 ng/mL, or Gleason score 8–10. A dose of 45 Gy (1.8 Gy/fraction) was delivered to the pelvic lymph nodes with a concomitant 22.5 Gy prostate intensity-modulated radiotherapy boost, to a total of 67.5 Gy (2.7 Gy/fraction) in 25 fractions within 5 weeks. Image guidance was performed using three gold seed fiducials. The National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0, and Radiation Therapy Oncology Group late morbidity scores were used to assess the acute and late toxicities, respectively. Biochemical failure was determined using the Phoenix definition. Results: A total of 97 patients were treated and followed up for a median of 39 months, with 88% having a minimum of 24 months of follow-up. The maximal toxicity scores were recorded. The grade of acute gastrointestinal toxicity was Grade 0 in 4%, 1 in 59%, and 2 in 37%. The grade of acute urinary toxicity was Grade 0 in 8%, 1 in 50%, 2 in 39%, and 3 in 4%. The grade of late gastrointestinal toxicity was Grade 0 in 54%, 1 in 40%, and 2 in 7%. No Grade 3 or greater late gastrointestinal toxicities developed. The grade of late urinary toxicity was Grade 0 in 82%, 1 in 9%, 2 in 5%, 3 in 3%, and 4 in 1% (1 patient). All severe toxicities (Grade 3 or greater) had resolved at the last follow-up visit. The 4-year biochemical disease-free survival rate was 90.5%. Conclusions: A hypofractionated intensity-modulated radiotherapy boost delivering 67.5 Gy in 25 fractions within 5 weeks combined with pelvic nodal radiotherapy and long-term androgen deprivation therapy was well tolerated, with low rates

  6. Radiochemoimmunotherapy with intensity-modulated concomitant boost: interim analysis of the REACH trial

    Directory of Open Access Journals (Sweden)

    Jensen Alexandra D

    2012-04-01

    Full Text Available Abstract Purpose To evaluate efficacy and toxicity clinical in the intensified treatment of locally advanced squamous cell carcinoma of the head and neck (SCCHN with the combination of chemotherapy, the EGFR antibody cetuximab, and intensity-modulated radiation therapy (IMRT in a concomitant boost concept. Methods REACH is a prospective, bi-centric phase II trial of carboplatin/5-FU and cetuximab weekly combined with IMRT. Primary endpoint is locoregional control, secondary endpoints include acute radiation effects and adverse events. Evaluation of disease response is carried out according to the Response Evaluation Criteria in Solid Tumors (RECIST; toxicity is assessed using NCI CTC v 3.0. Results Treatment was tolerated moderately well, acneiforme erythema occurred in 74.1% (grade II/III, mucositis grade III in 28.6%, and radiation dermatitis grade III in 14.3%. Higher-grade side-effects resolved quickly until the first follow-up post treatment. Objective response rates were promising with 28.6% CR at first follow-up and 92.9% thereafter. Conclusion The combination of standard carboplatin/5-FU and cetuximab is feasible and results in promising objective response rates. The use of an IMRT concomitant boost is practicable in a routine clinical setting resulting in only moderate overall toxicity of the regimen. Trial Registration Number ISRCTN87356938.

  7. Radiochemoimmunotherapy with intensity-modulated concomitant boost: interim analysis of the REACH trial

    International Nuclear Information System (INIS)

    To evaluate efficacy and toxicity clinical in the intensified treatment of locally advanced squamous cell carcinoma of the head and neck (SCCHN) with the combination of chemotherapy, the EGFR antibody cetuximab, and intensity-modulated radiation therapy (IMRT) in a concomitant boost concept. REACH is a prospective, bi-centric phase II trial of carboplatin/5-FU and cetuximab weekly combined with IMRT. Primary endpoint is locoregional control, secondary endpoints include acute radiation effects and adverse events. Evaluation of disease response is carried out according to the Response Evaluation Criteria in Solid Tumors (RECIST); toxicity is assessed using NCI CTC v 3.0. Treatment was tolerated moderately well, acneiforme erythema occurred in 74.1% (grade II/III), mucositis grade III in 28.6%, and radiation dermatitis grade III in 14.3%. Higher-grade side-effects resolved quickly until the first follow-up post treatment. Objective response rates were promising with 28.6% CR at first follow-up and 92.9% thereafter. The combination of standard carboplatin/5-FU and cetuximab is feasible and results in promising objective response rates. The use of an IMRT concomitant boost is practicable in a routine clinical setting resulting in only moderate overall toxicity of the regimen.

  8. Intensity-modulated radiotherapy with simultaneous integrated boost for locoregionally advanced nasopharyngeal carcinoma

    International Nuclear Information System (INIS)

    To compare the treatment outcomes of intensity-modulated radiotherapy with simultaneous integrated boost (IMRT-SIB) alone to concurrent chemoradiotherapy (CCRT) for locoregionally advanced nasopharyngeal carcinoma (NPC). From November 2001 to December 2009, 333 patients with pathologically diagnosed, locoregionally advanced NPC were treated by IMRT-SIB with or without weekly cisplatin concurrent chemotherapy at our institute. Among them, 62 patients received neo- or adjuvant chemotherapy or molecular target drugs were excluded from this analysis. There were 129 patients received IMRT-SIB alone, and 142 patients received IMRT-SIB with weekly cisplatin 30 mg/m2 for 7 weeks. The radiotherapy protocol was identical for each group. There were no significant differences in survival between CCRT and IMRT-SIB group in terms of gender, T/N classifications and concurrent chemoradiotherapy. The 5-year local control (LC), overall survival (OS), disease-free survival (DFS) and distant metastasis-free survival (DMFS) for the entire group were 87.0%, 79.4%, 69.7 and 83.3%, respectively. The LC, OS, DFS and DMFS for CCRT and IMRT-SIB alone groups were 80.6% vs. 90.8% (P = 0.10), 71.7% vs. 83.2% (P = 0.201), 63.9% vs. 74.6% (P = 0.07), and 79.6% vs. 86.0% (P = 0.27), respectively. Compared to CCRT, IMRT-SIB alone had demonstrated similar disease LC, OS, DFS and DMFS in locoregionally advanced NPC. Careful radiation target volume design and simultaneous integrated boost may play a role that overrides the benefit from concurrent chemotherapy. Further investigation with randomized study is necessary to determine whether IMRT-SIB alone can achieve similar outcomes of concurrent chemoradiotherapy

  9. Simultaneous integrated boost for adjuvant treatment of breast cancer- intensity modulated vs. conventional radiotherapy: The IMRT-MC2 trial

    OpenAIRE

    Tiefenbacher Uta; Hüsing Johannes; Sohn Christof; Heil Joerg; Sterzing Florian; Fetzner Leonie; Häfner Matthias F; Jensen Alexandra D; Askoxylakis Vasileios; Wenz Frederik; Debus Jürgen; Hof Holger

    2011-01-01

    Abstract Background Radiation therapy is an essential modality in the treatment of breast cancer. Addition of radiotherapy to surgery has significantly increased local control and survival rates of the disease. However, radiotherapy is also associated with side effects, such as tissue fibrosis or enhanced vascular morbidity. Modern radiotherapy strategies, such as intensity modulated radiotherapy (IMRT), can shorten the overall treatment time by integration of the additional tumor bed boost s...

  10. Simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) in nasopharyngeal cancer

    International Nuclear Information System (INIS)

    Purpose: To assess the efficacy and safety of using simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) to treat nasopharyngeal cancer (NPC) in a Caucasian cohort. Outcome was analyzed with respect to dose-volume histogram (DVH) values. Patients and Methods: Between 03/2002 and 01/2008, 39 NPC patients underwent SIB-IMRT (37 Caucasians; 31 males; mean age 53 years [16-78 years]). 41% presented with WHO (World Health Organization) type 1 unfavorable histology, 85% with stage III/IV disease. 19 patients had total gross tumor volume (GTV) 16-70 cm3 (mean 36 cm3), while 16 had GTV > 70 cm3 (73-217 cm3; mean 115 cm3). All patients with stage II-IV disease received concomitant cisplatin. The prescribed SIB dose delivered to the planning target volume (PTV) was 70 Gy (2.00 Gy/fraction) in 17, 69.6 Gy (2.11 Gy/fraction) in 19, and 66 Gy (2.20 Gy/fraction) in three patients. Results: 3-year local relapse-free, nodal relapse-free, distant metastases-free, disease-free rates and overall survival were 86%, 89%, 85%, 72%, and 85% (median follow-up 30 months [8-71 months]). Histology was a significant prognostic factor concerning overall survival, with worst prognosis in WHO type 1 compared to type 2/3 (75% vs. 93%; p = 0.03). There was a trend in favor of WHO type 2/3 regarding local control (74% vs. 94%; p = 0.052). The PTV DVHs showed a slight left shift compared to reported series. Three patients developed grade 3 late effects (xerostomia [n=2], dysphagia [n=1], hearing loss [n=1]). Conclusion: In comparison with predominantly Asian NPC IMRT series in the literature, chemo-IMRT in the own Caucasian cohort, characterized by less radioresponsive WHO type 1, was equally effective. Treatment tolerance was excellent. (orig.)

  11. Monte Carlo dose verification of prostate patients treated with simultaneous integrated boost intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    To evaluate the dosimetric differences between Superposition/Convolution (SC) and Monte Carlo (MC) calculated dose distributions for simultaneous integrated boost (SIB) prostate cancer intensity modulated radiotherapy (IMRT) compared to experimental (film) measurements and the implications for clinical treatments. Twenty-two prostate patients treated with an in-house SIB-IMRT protocol were selected. SC-based plans used for treatment were re-evaluated with EGS4-based MC calculations for treatment verification. Accuracy was evaluated with-respect-to film-based dosimetry. Comparisons used gamma (γ)-index, distance-to-agreement (DTA), and superimposed dose distributions. The treatment plans were also compared based on dose-volume indices and 3-D γ index for targets and critical structures. Flat-phantom comparisons demonstrated that the MC algorithm predicted measurements better than the SC algorithm. The average PTVprostate D98 agreement between SC and MC was 1.2% ± 1.1. For rectum, the average differences in SC and MC calculated D50 ranged from -3.6% to 3.4%. For small bowel, there were up to 30.2% ± 40.7 (range: 0.2%, 115%) differences between SC and MC calculated average D50 index. For femurs, the differences in average D50 reached up to 8.6% ± 3.6 (range: 1.2%, 14.5%). For PTVprostate and PTVnodes, the average gamma scores were >95.0%. MC agrees better with film measurements than SC. Although, on average, SC-calculated doses agreed with MC calculations within the targets within 2%, there were deviations up to 5% for some patient's treatment plans. For some patients, the magnitude of such deviations might decrease the intended target dose levels that are required for the treatment protocol, placing the patients in different dose levels that do not satisfy the protocol dose requirements

  12. Simultaneous integrated boost-intensity modulated radiation therapy for inoperable hepatocellular carcinoma

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    Kim, Tae Hyun; Park, Joong-Won; Kim, Yeon-Joo; Kim, Bo Hyun; Woo, Sang Myung; Moon, Sung Ho; Kim, Sang Soo; Lee, Woo Jin; Kim, Dae Yong; Kim, Chang-Min [National Cancer Center, Center for Liver Cancer, Research Institute and Hospital, Goyang-si, Gyeonggi-do (Korea, Republic of)

    2014-10-15

    The aim of this work was to evaluate the clinical efficacy and safety of simultaneous integrated boost-intensity modulated radiation therapy (SIB-IMRT) in patients with inoperable hepatocellular carcinoma (HCC). A total of 53 patients with inoperable HCC underwent SIB-IMRT using two dose-fractionation schemes, depending on the proximity of gastrointestinal structures. The 41 patients in the low dose-fractionation (LD) group, with internal target volume (ITV) < 1 cm from gastrointestinal structures, received total doses of 55 and 44 Gy in 22 fractions to planning target volume 1 (PTV1) and 2 (PTV2), respectively. The 12 patients in the high dose-fractionation (HD) group, with ITV ≥ 1 cm from gastrointestinal structures, received total doses of 66 and 55 Gy in 22 fractions to the PTV1 and PTV2, respectively. Overall, treatment was well tolerated, with no grade > 3 toxicity. The LD group had larger sized tumors (median: 6 vs. 3.4 cm) and greater frequencies of vascular invasion (80.6 vs. 16.7 %) than patients in the HD group (p < 0.05 each). The median overall survival (OS) was 25.1 months and the actuarial 2-year local progression-free survival (LPFS), relapse-free survival (RFS), and OS rates were 67.3, 14.7, and 54.7 %, respectively. The HD group tended to show better tumor response (100 vs. 62.2 %, p = 0.039) and 2-year LPFS (85.7 vs. 59 %, p = 0.119), RFS (38.1 vs. 7.3 %, p = 0.063), and OS (83.3 vs. 44.3 %, p = 0.037) rates than the LD group. Multivariate analysis showed that tumor response was significantly associated with OS. SIB-IMRT is feasible and safe for patients with inoperable HCC. (orig.) [German] Ziel der Arbeit war es, die klinische Wirksamkeit und die Sicherheit der intensitaetsmodulierten Radiotherapie mit simultanem integriertem Boost (SIB-IMRT) fuer Patienten mit einem inoperablen hepatozellulaeren Karzinom (HCC) zu evaluieren. Bei 53 Patienten mit inoperablem HCC wurden zwei unterschiedliche Dosierungskonzepte je nach Lagebeziehung des

  13. Simultaneous integrated boost for adjuvant treatment of breast cancer- intensity modulated vs. conventional radiotherapy: The IMRT-MC2 trial

    Directory of Open Access Journals (Sweden)

    Tiefenbacher Uta

    2011-06-01

    Full Text Available Abstract Background Radiation therapy is an essential modality in the treatment of breast cancer. Addition of radiotherapy to surgery has significantly increased local control and survival rates of the disease. However, radiotherapy is also associated with side effects, such as tissue fibrosis or enhanced vascular morbidity. Modern radiotherapy strategies, such as intensity modulated radiotherapy (IMRT, can shorten the overall treatment time by integration of the additional tumor bed boost significantly. To what extent this might be possible without impairing treatment outcome and cosmetic results remains to be clarified. Methods/Design The IMRT-MC2 study is a prospective, two armed, multicenter, randomized phase-III-trial comparing intensity modulated radiotherapy with integrated boost to conventional radiotherapy with consecutive boost in patients with breast cancer after breast conserving surgery. 502 patients will be recruited and randomized into two arms: patients in arm A will receive IMRT in 28 fractions delivering 50.4 Gy to the breast and 64.4 Gy to the tumor bed by integrated boost, while patients in arm B will receive conventional radiotherapy of the breast in 28 fractions to a dose of 50.4 Gy and consecutive boost in 8 fractions to a total dose of 66.4 Gy. Discussion Primary objectives of the study are the evaluation of the cosmetic results 6 weeks and 2 years post treatment and the 2- and 5-year local recurrence rates for the two different radiotherapy strategies. Secondary objectives are long term overall survival, disease free survival and quality of life. Trial Registration ClinicalTrials.gov Protocol ID: NCT01322854.

  14. Simultaneous integrated boost for adjuvant treatment of breast cancer- intensity modulated vs. conventional radiotherapy: The IMRT-MC2 trial

    International Nuclear Information System (INIS)

    Radiation therapy is an essential modality in the treatment of breast cancer. Addition of radiotherapy to surgery has significantly increased local control and survival rates of the disease. However, radiotherapy is also associated with side effects, such as tissue fibrosis or enhanced vascular morbidity. Modern radiotherapy strategies, such as intensity modulated radiotherapy (IMRT), can shorten the overall treatment time by integration of the additional tumor bed boost significantly. To what extent this might be possible without impairing treatment outcome and cosmetic results remains to be clarified. The IMRT-MC2 study is a prospective, two armed, multicenter, randomized phase-III-trial comparing intensity modulated radiotherapy with integrated boost to conventional radiotherapy with consecutive boost in patients with breast cancer after breast conserving surgery. 502 patients will be recruited and randomized into two arms: patients in arm A will receive IMRT in 28 fractions delivering 50.4 Gy to the breast and 64.4 Gy to the tumor bed by integrated boost, while patients in arm B will receive conventional radiotherapy of the breast in 28 fractions to a dose of 50.4 Gy and consecutive boost in 8 fractions to a total dose of 66.4 Gy. Primary objectives of the study are the evaluation of the cosmetic results 6 weeks and 2 years post treatment and the 2- and 5-year local recurrence rates for the two different radiotherapy strategies. Secondary objectives are long term overall survival, disease free survival and quality of life. ClinicalTrials.gov Protocol ID: http://www.clinicaltrials.gov/ct2/show/NCT01322854

  15. Optimal beam design on intensity-modulated radiation therapy with simultaneous integrated boost in nasopharyngeal cancer

    International Nuclear Information System (INIS)

    This study aims to determine the optimal beam design among various combinations of field numbers and beam trajectories for intensity-modulated radiation therapy (IMRT) with simultaneous integrated boost (SIB) technique for the treatment of nasopharyngeal cancer (NPC). We used 10 fields with gantry angles of 155°, 130°, 75°, 25°, 0° L, 0° R, 335°, 285°, 230°, and 205° denoted as F10. To decrease doses in the spinal cord, the F10 technique was designed by featuring 2 pairs of split-opposed beam fields at 155° to 335° and 205° to 25°, as well as one pair of manually split beam fields at 0°. The F10 technique was compared with 4 other common field arrangements: F7E, 7 fields with 50° equally spaced gantry angles; F7, the basis of F10 with 155°, 130°, 75°, 0°, 285°, 230°, and 205°; F9E, 9 fields with 40° equally spaced gantry angles; and FP, 7 posterior fields with 180°, 150°, 120°, 90°, 270°, 240°, and 210°. For each individual case of 10 patients, the customized constraints derived after optimization with the standard F10 technique were applied to 4 other field arrangements. The 4 new optimized plans of each individual case were normalized to achieve the same coverage of planning target volume (PTV)63 Gy as that of the standard F10 technique. The F10 field arrangement exhibited the best coverage in PTV70 Gy and the least mean dose in the trachea-esophagus region. Furthermore, the F10 field arrangement demonstrated the highest level of conformity in the low-dose region and the least monitor unit. The F10 field arrangement performed more outstandingly than the other field arrangements in PTV70 Gy coverage and spared the central organ. This arrangement also exhibited the highest conformity and delivery efficiency. The F10 technique is recommended as the standard beam geometry for the SIB-IMRT of NPC

  16. Dosimetric comparison of the related parameters between simultaneous integrated boost intensity-modulated radiotherapy and sequential boost conformal radiotherapy for postoperative malignant glioma of the brain

    International Nuclear Information System (INIS)

    Objective: To compare the dosimetric of different parameter of simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) with sequential boost conformal radiotherapy (SB-CRT) for postoperative malignant glioma of the brain. Methods: Ten patients with malignant glioma of brain were selected to study. Each patient was simulated all by CT and MRI, and the imagings of CT and MRI were all sent to Pinnacle3 planning system. The fusion technology with MR-CT imaging was used on Pinnacle3 planning system. The target volume was delineated and defined based on MRI. The postoperative residual lesion and resection cavity were defined as gross tumor volume (GTV) and expanded GTV some scope was defined as clinical target volume (CTV). The margins of GTV expanded 10 mm and 25 mm were defined as CTV1 and CTV2 respectively. CTV1 and CTV2 all enlarged 5 mm were defined as PTV1 and PTV2 respectively. The plans of simultaneous integrated boost intensity-modulated radiotherapy and sequential boost conformal radiotherapy were respectively designed for each patient using Pinnacle3 planning system and the dosimetric of different parameter was compared. The prescribe dose of SIB-IMRT was PTV1: 62.5 Gy/25 f, PTV2: 50.0 Gy/25 f; and SB-CRT was PTV1: 66.0 Gy/33 f, PTV2: 50.0 Gy/25 f. The dosimetries of different parameters of SIB-IMRT and SB-CRT were compared by using Paired-Samples T Test. Results: The maximum and mean dose of PTV1, PTV2, and brainstem were of significant difference (P0.05). Conclusion: The SIB-IMRT plan is better than the SB-CRT plan. The CI and HI of SIB-IMRT are superior to SB-CRT. At the same time, it can preserve the important organs such as brainstem and reduce the mean dose of whole brain. On the other hand it can shorten the total period of therapy time. (authors)

  17. Intensity-modulated radiotherapy with simultaneous modulated accelerated boost technique and chemotherapy in patients with nasopharyngeal carcinoma

    International Nuclear Information System (INIS)

    To present our experience of intensity-modulated radiotherapy (IMRT) with simultaneous modulated accelerated radiotherapy (SMART) boost technique in patients with nasopharyngeal carcinoma (NPC). Sixty eight patients of NPC were treated between April 2006 and December 2011 including 45 males and 23 females with mean age of 46 (range 15–78). Stage distribution was; stage I 3, stage II 7, stage III 26 and stage IV 32. Among 45 (66.2%) evaluated patients for presence of Epstein-Barr virus (EBV), 40 (88.8%) were positive for EBV. Median radiation doses delivered to gross tumor volume (GTV) and positive neck nodes were 66–70 Gy, 63 Gy to clinical target volume (CTV) and 50.4 Gy to clinically negative neck. In addition 56 (82.4%) patients with bulky tumors (T4/N2+) received neoadjuvant chemotherapy 2–3 cycles (Cisplatin/Docetaxel or Cisplatin/Epirubicin or Cisplatin/5 Flourouracil). Concurrent chemotherapy with radiation was weekly Cisplatin 40 mg/m2 (40 patients) or Cisplatin 100 mg/m2 (28 patients). With a median follow up of 20 months (range 3–43), one patient developed local recurrence, two experienced regional recurrences and distant failure was seen in 3 patients. Estimated 3 year disease free survival (DFS) was 94%. Three year DFS for patients with EBV was 100% as compared to 60% without EBV (p = 0.0009). Three year DFS for patients with undifferentiated histology was 98% as compared to 82% with other histologies (p = 0.02). Acute grade 3 toxicity was seen as 21 (30.9%) having G-III mucositis and 6 (8.8%) with G-III skin reactions. Late toxicity was minimal and loss of taste was seen in 3 patients (7.5%) at time of analysis. IMRT with SMART in combination with chemotherapy is feasible and effective in terms of both the clinical response and safety profile. EBV, histopathology and nodal involvement were found important prognostic factors for locoregional recurrence

  18. Comparison of conformal and intensity-modulated techniques for simultaneous integrated boost radiotherapy of upper esophageal carcinoma

    Institute of Scientific and Technical Information of China (English)

    Wei-Hua Fu; Lu-Hua Wang; Zong-Mei Zhou; Jian-Rong Dai; Yi-Min Hu; Lu-Jun Zhao

    2004-01-01

    AIM: To compare intensity-modulated radiotherapy (IMRT)with conformal radiotherapy (CRT) by investigating the dose profiles of primary tumors, electively treated regions, and the doses to organs at risk.METHODS: CRT and IMRT plans were designed for five patients with upper esophageal carcinoma. For each patient,target volumes for primary lesions (67.2 Gy) and electively treated regions (50.4 Gy) were predefined. An experienced planner manually designed one CRT plan. Four IMRT plans were generated with the same dose-volume constraints, but with different beam arrangements. Indices including dose distributions, dose volume histograms (DVHs) and conformity index were compared.RESULTS: The plans with three intensity-modulated beams were discarded because the doses to spinal cord were lager than the tolerable dose 45Gy, and the dose on areas near the skin was up to 50Gy. When the number of intensity beams increased to five, IMRT plans were better than CRT plans in terms of the dose conformity and homogeneity of targets and the dose to OARs. The dose distributions changed little when the beam number increased from five to seven and nine.CONCLUSION: IMRT is superior to CRT for the treatment of upper esophageal carcinoma with simultaneous integrated boost (SIB). Five equispaced coplanar intensity-modulated beams can produce desirable dose distributions. The primary tumor can get higher equivalent dose by SIB technique.The SIB-IMRT technique shortens the total treatment time,and is an easier, more efficient, and perhaps a less errorprone way in delivering IMRT.

  19. Whole breast and excision cavity radiotherapy plan comparison: Conformal radiotherapy with sequential boost versus intensity-modulated radiation therapy with a simultaneously integrated boost

    International Nuclear Information System (INIS)

    A comparative study was conducted comparing the difference between (1) conformal radiotherapy (CRT) to the whole breast with sequential boost excision cavity plans and (2) intensity-modulated radiation therapy (IMRT) to the whole breast with simultaneously integrated boost to the excision cavity. The computed tomography (CT) data sets of 25 breast cancer patients were used and the results analysed to determine if either planning method produced superior plans. CT data sets from 25 past breast cancer patients were planned using (1) CRT prescribed to 50 Gy in 25 fractions (Fx) to the whole-breast planning target volume (PTV) and 10 Gy in 5Fx to the excision cavity and (2) IMRT prescribed to 60 Gy in 25Fx, with 60 Gy delivered to the excision cavity PTV and 50 Gy delivered to the whole-breast PTV, treated simultaneously. In total, 50 plans were created, with each plan evaluated by PTV coverage using conformity indices, plan maximum dose, lung dose, and heart maximum dose for patients with left-side lesions. CRT plans delivered the lowest plan maximum doses in 56% of cases (average CRT = 6314.34 cGy, IMRT = 6371.52 cGy). They also delivered the lowest mean lung dose in 68% of cases (average CRT = 1206.64 cGy, IMRT = 1288.37 cGy) and V20 in 88% of cases (average CRT = 20.03%, IMRT = 21.73%) and V30 doses in 92% of cases (average CRT = 16.82%, IMRT = 17.97%). IMRT created more conformal plans, using both conformity index and conformation number, in every instance, and lower heart maximum doses in 78.6% of cases (average CRT = 5295.26 cGy, IMRT = 5209.87 cGy). IMRT plans produced superior dose conformity and shorter treatment duration, but a slightly higher planning maximum and increased lung doses. IMRT plans are also faster to treat on a daily basis, with shorter fractionation

  20. Improving bladder cancer treatment with radiotherapy using separate intensity modulated radiotherapy plans for boost and elective fields

    International Nuclear Information System (INIS)

    The aim of this study is to investigate to what extent IMRT can decrease the dose to the organs at risk in bladder cancer treatment compared with conformal treatment while making separate treatment plans for the elective field and the boost. Special attention is paid to sparing small intestines. Twenty patients who were treated with the field-in-field technique (FiF) were re-planned with intensity modulated radiotherapy (IMRT) using five and seven beams, respectively. Separate treatment plans were made for the elective field (including the pelvic lymph nodes) and the boost, which enables position correction for bone and tumour separately. The prescribed dose was 40 Gy to the elective field and 55 or 60 Gy to the planning target volume (PTV). For bladder and rectum, V45Gy and V55Gy were compared, and for small intestines, V25Gy and V40Gy. The dose distribution with IMRT conformed better to the shape of the target. There was no significant difference between the techniques in dose to the healthy bladder. The median V40Gy of the small intestines decreased from 114 to 66 cc (P = 0.001) with five beam IMRT, and to 55 cc (P = 0.001) with seven beam IMRT compared with FiF. V45Gy for rectum decreased from 34.2% to 17.5% (P = 0.004) for both five and seven beam plans, while V55Gy for rectum remained the same. With IMRT, a statistically significant dose decrease to the small intestines can be achieved while covering both tumour and elective PTV adequately.

  1. Ototoxicity evaluation in medulloblastoma patients treated with involved field boost using intensity-modulated radiation therapy (IMRT): a retrospective review

    International Nuclear Information System (INIS)

    Ototoxicity is a known side effect of combined radiation therapy and cisplatin chemotherapy for the treatment of medulloblastoma. The delivery of an involved field boost by intensity modulated radiation therapy (IMRT) may reduce the dose to the inner ear when compared with conventional radiotherapy. The dose of cisplatin may also affect the risk of ototoxicity. A retrospective study was performed to evaluate the impact of involved field boost using IMRT and cisplatin dose on the rate of ototoxicity. Data from 41 medulloblastoma patients treated with IMRT were collected. Overall and disease-free survival rates were calculated by Kaplan-Meier method Hearing function was graded according to toxicity criteria of Pediatric Oncology Group (POG). Doses to inner ear and total cisplatin dose were correlated with hearing function by univariate and multivariate data analysis. After a mean follow-up of 44 months (range: 14 to 72 months), 37 patients remained alive, with two recurrences, both in spine with CSF involvement, resulting in a disease free-survival and overall survival of 85.2% and 90.2%, respectively. Seven patients (17%) experienced POG Grade 3 or 4 toxicity. Cisplatin dose was a significant factor for hearing loss in univariate analysis (p < 0.03). In multivariate analysis, median dose to inner ear was significantly associated with hearing loss (p < 0.01). POG grade 3 and 4 toxicity were uncommon with median doses to the inner ear bellow 42 Gy (p < 0.05) and total cisplatin dose of less than 375 mg/m2 (p < 0.01). IMRT leads to a low rate of severe ototoxicity. Median radiation dose to auditory apparatus should be kept below 42 Gy. Cisplatin doses should not exceed 375 mg/m2

  2. Impact of intensity-modulated radiation therapy as a boost treatment on the lung-dose distributions for non-small-cell lung cancer

    International Nuclear Information System (INIS)

    Purpose: To investigate the feasibility of intensity-modulated radiotherapy (IMRT) as a method of boost radiotherapy after the initial irradiation by the conventional anterior/posterior opposed beams for centrally located non-small-cell lung cancer through the evaluation of dose distributions according to the various boost methods. Methods and Materials: Seven patients with T3 or T4 lung cancer and mediastinal node enlargement who previously received radiotherapy were studied. All patients underwent virtual simulation retrospectively with the previous treatment planning computed tomograms. Initial radiotherapy plans were designed to deliver 40 Gy to the primary tumor and involved nodal regions with the conventional anterior/posterior opposed beams. Two radiation dose levels, 24 and 30 Gy, were used for the boost radiotherapy plans, and four different boost methods (a three-dimensional conformal radiotherapy [3DCRT], five-, seven-, and nine-beam IMRT) were applied to each dose level. The goals of the boost plans were to deliver the prescribed radiation dose to 95% of the planning target volume (PTV) and minimize the volumes of the normal lungs and spinal cord irradiated above their tolerance doses. Dose distributions in the PTVs and lungs, according to the four types of boost plans, were compared in the boost and sum plans, respectively. Results: The percentage of lung volumes irradiated >20 Gy (V20) was reduced significantly in the IMRT boost plans compared with the 3DCRT boost plans at the 24- and 30-Gy dose levels (p 0.007 and 0.0315 respectively). Mean lung doses according to the boost methods were not different in the 24- and 30-Gy boost plans. The conformity indexes (CI) of the IMRT boost plans were lower than those of the 3DCRT plans in the 24- and 30-Gy plans (p = 0.001 in both). For the sum plans, there was no difference of the dose distributions in the PTVs and lungs according to the boost methods. Conclusions: In the boost plans the V20s and CIs were

  3. Dosimetric benefit of DMLC tracking for conventional and sub-volume boosted prostate intensity-modulated arc radiotherapy

    International Nuclear Information System (INIS)

    This study investigated the dosimetric impact of uncompensated motion and motion compensation with dynamic multileaf collimator (DMLC) tracking for prostate intensity modulated arc therapy. Two treatment approaches were investigated; a conventional approach with a uniform radiation dose to the target volume and an intraprostatic lesion (IPL) boosted approach with an increased dose to a subvolume of the prostate. The impact on plan quality of optimizations with a leaf position constraint, which limited the distance between neighbouring adjacent MLC leaves, was also investigated. Deliveries were done with and without DMLC tracking on a linear acceleration with a high-resolution MLC. A cylindrical phantom containing two orthogonal diode arrays was used for dosimetry. A motion platform reproduced six patient-derived prostate motion traces, with the average displacement ranging from 1.0 to 8.9 mm during the first 75 s. A research DMLC tracking system was used for real-time motion compensation with optical monitoring for position input. The gamma index was used for evaluation, with measurements with a static phantom or the planned dose as reference, using 2% and 2 mm gamma criteria. The average pass rate with DMLC tracking was 99.9% (range 98.7–100%, measurement as reference), whereas the pass rate for untracked deliveries decreased distinctly as the average displacement increased, with an average pass rate of 61.3% (range 32.7–99.3%). Dose–volume histograms showed that DMLC tracking maintained the planned dose distributions in the presence of motion whereas traces with >3 mm average displacement caused clear plan degradation for untracked deliveries. The dose to the rectum and bladder had an evident dependence on the motion direction and amplitude for untracked deliveries, and the dose to the rectum was slightly increased for IPL boosted plans compared to conventional plans for anterior motion with large amplitude. In conclusion, optimization using a leaf position

  4. Intensity-modulated radiotherapy versus conventional three-dimensional conformal radiotherapy for boost or salvage treatment of nasopharyngeal carcinoma

    International Nuclear Information System (INIS)

    Purpose: To compare intensity-modulated radiotherapy (IMRT) and conventional three-dimensional conformal radiotherapy (3D-CRT) for the boost treatment of new-onset nasopharyngeal carcinoma (NPC) or the salvage treatment of locally recurrent NPC. Methods and Materials: Between January 14 and February 23, 2000, 5-field 3D-CRT treatment plans were generated for 14 consecutive NPC patients using the ADAC Pinnacle planning system in Chang Gung Memorial Hospital, Kaohsiung, Taiwan. The planning data of these patients were later transferred to Memorial Sloan-Kettering Cancer Center, where new IMRT plans, also using 5-7 radiation fields were created for each patient using an inverse treatment planning system. The IMRT and 3D-CRT plans were compared for all 14 patients. The relationship between the anatomic shapes and locations of targets and the results of different plans were studied. Results: Target doses were more homogeneous in IMRT plans. The average maximal brainstem dose (D05, the dose received by 5% of the brainstem volume) decreased from 30.9% of the prescription dose with 3D-CRT to 15.3% and 14.7% with 5- and 7-field IMRT, respectively (p=0.004 and 0.003, respectively, compared with 3D-CRT, paired Student's t test). Five anatomic factors were found that predicted greater benefits with IMRT. These factors were (1) vertical length of target >7 cm, (2) minimal distance between target and brainstem 0.6 cm, (4) maximal AP overlap of target and spinal cord >1 cm, and (5) vertical overlap of target and eyes >0 cm. For the 7 patients with at least 1 of these 5 anatomic factors, the benefits achieved by IMRT planning would have been greater than the benefits for the other 7 patients (p=0.005, Fisher's exact test). Conclusion: For boost or salvage treatment of NPC, lower normal tissue doses and more homogeneous target doses were achieved with IMRT plans. For NPC patients with at least 1 of the 5 anatomic factors, IMRT is highly recommended

  5. Four-Week Course of Radiation for Breast Cancer Using Hypofractionated Intensity Modulated Radiation Therapy With an Incorporated Boost

    International Nuclear Information System (INIS)

    Purpose: Standard radiation for early breast cancer requires daily treatment for 6 to 7 weeks. This is an inconvenience to many women, and for some a barrier for breast conservation. We present the acute toxicity of a 4-week course of hypofractionated radiation. Methods and Materials: A total of 75 patients completed radiation on a Phase II trial approved by the hospital institutional review board. Eligibility criteria were broad to include any patient normally eligible for standard radiation: age ≥18 years, invasive or in situ cancer, American Joint Committee on Cancer Stage 0 to II, breast-conserving surgery, and any systemic therapy not given concurrently. The median age was 52 years (range, 31-81 years). Of the patients, 15% had ductal carcinoma in situ, 67% T1, and 19% T2; 71% were N0, 17% N1, and 12% NX. Chemotherapy was given before radiation in 44%. Using photon intensity-modulated radiation therapy and incorporated electron beam boost, the whole breast received 45 Gy and the lumpectomy bed 56 Gy in 20 treatments over 4 weeks. Results: The maximum acute skin toxicity by the end of treatment was Grade 0 in 9 patients (12%), Grade 1 in 49 (65%) and Grade 2 in 17 (23%). There was no Grade 3 or higher skin toxicity. After radiation, all Grade 2 toxicity had resolved by 6 weeks. Hematologic toxicity was Grade 0 in most patients except for Grade 1 neutropenia in 2 patients, and Grade 1 anemia in 11 patients. There were no significant differences in baseline vs. 6-week posttreatment patient-reported or physician-reported cosmetic scores. Conclusions: This 4-week course of postoperative radiation using intensity-modulated radiation therapy is feasible and is associated with acceptable acute skin toxicity and quality of life. Long-term follow-up data are needed. This radiation schedule may represent an alternative both to longer 6-week to 7-week standard whole-breast radiation and more radically shortened 1-week, partial-breast treatment schedules

  6. Intensity-modulated pelvic radiation therapy and simultaneous integrated boost to the prostate area in patients with high-risk prostate cancer: a preliminary report of disease control

    OpenAIRE

    Saracino, Biancamaria; Petrongari, Maria Grazia; Marzi, Simona; Bruzzaniti, Vicente; Sara, Gomellini; Arcangeli, Stefano; Arcangeli, Giorgio; Pinnarò, Paola; Giordano, Carolina; Ferraro, Anna Maria; Strigari, Lidia

    2014-01-01

    The aim of the study was to report the clinical results in patients with high-risk prostate cancer treated with pelvic intensity-modulated radiation therapy (IMRT) and simultaneous integrated boost (SIB) to the prostate area. A total of 110 patients entered our study, 37 patients presented with localized prostate cancer and radiological evidence of node metastases or ≥15% estimated risk of lymph node (LN) involvement, while 73 patients underwent postoperative adjuvant or salvage irradiation f...

  7. Long-term outcome and late toxicities of simultaneous integrated boost-intensity modulated radiotherapy in pediatric and adolescent nasopharyngeal carcinoma

    OpenAIRE

    Li-Zhi Liu; Xiao-Li Yu; Wen-Fei Li; Lei Chen; Yan-Ping Mao; Ling-Long Tang; Xu Liu; Chang-Juan Tao; Rong Zhang; Ai-Hua Lin; Jun Ma; Ying Sun

    2013-01-01

    The application of simultaneous integrated boost-intensity modulated radiotherapy (SIB-IMRT) in pediatric and adolescent nasopharyngeal carcinoma (NPC) is underevaluated. This study aimed to evaluate long-term outcome and late toxicities in pediatric and adolescent NPC after SIB-IMRT combined with chemotherapy. Thirty-four patients (aged 8-20 years) with histologically proven, non-disseminated NPC treated with SIB-IMRT were enrolled in this retrospective study. The disease stage distribution ...

  8. Long-term outcome and late toxicities of simultaneous integrated boost-intensity modulated radiotherapy in pediatric and adolescent nasopharyngeal carcinoma

    OpenAIRE

    Tao, Chang-Juan; Liu, Xu; Tang, Ling-Long; Mao, Yan-Ping; Chen, Lei; Li, Wen-Fei; Yu, Xiao-Li; Liu, Li-Zhi; Zhang, Rong; Lin, Ai-Hua; Ma, Jun; Sun, Ying

    2013-01-01

    The application of simultaneous integrated boost-intensity modulated radiotherapy (SIB-IMRT) in pediatric and adolescent nasopharyngeal carcinoma (NPC) is underevaluated. This study aimed to evaluate long-term outcome and late toxicities in pediatric and adolescent NPC after SIB-IMRT combined with chemotherapy. Thirty-four patients (aged 8–20 years) with histologically proven, non-disseminated NPC treated with SIB-IMRT were enrolled in this retrospective study. The disease stage distribution ...

  9. Simultaneous integrated boost with intensity modulated radiation therapy in brain oligometastases: A feasible technique for developing countries

    Directory of Open Access Journals (Sweden)

    Vivek Tiwari

    2015-01-01

    Full Text Available Introduction: To analyze the pattern of brain metastasis (BM, and to use intensity modulated radiation therapy (IMRT for target dose escalation in cases with ≤3 metastatic lesions (oligometastases. Materials and Methods: Thirty-two consecutive cases of BM treated during September 2009 to August 2012 were analyzed retrospectively. Results: The study comprised 13 males (40.62% and 19 females (59.37%. Thirteen (40% patients presented with disseminated intracranial metastases, while 19 (60% had ≤3 foci. In 25 cases (78%, the primary was located either in the breast (14 cases or lung (11 cases. The 13 patients with disseminated intracranial metastases received whole brain radiation therapy to a dose of 30 Gy/10-12 daily fractions (Group A while the 19 cases with ≤3 lesions received an additional dose of 6-10 Gy to gross lesions using a simultaneous integrated boost (SIB with IMRT thus receiving a total dose of 36-40 Gy/12-15 fractions (Group B. Overall survival (OS for the breast primary was 6.3 and lung primary was 5.3 months, respectively. The mean OS for breast cases in Group B was higher (9.5 months as compared to Group A cases (1.9 months and was statistically significant (P = 0.0056. Similarly, primary lung cancer cases in Group B showed a mean OS of 8.75 months versus 2.6 months for Group A cases (P = 0.213. Conclusions: IMRT is a safe and effective technique in cases with oligometastases for dose escalation in the form of SIB.

  10. Quality of Life After Hypofractionated Concomitant Intensity-Modulated Radiotherapy Boost for High-Risk Prostate Cancer

    International Nuclear Information System (INIS)

    Purpose: To evaluate the change in health-related quality of life (QOL) of patients with high-risk prostate cancer treated using hypofractionated radiotherapy combined with long-term androgen deprivation therapy. Methods and Materials: A prospective Phase I–II study enrolled patients with any of the following: clinical Stage T3 disease, prostate-specific antigen level ≥20 ng/mL, or Gleason score 8–10. Radiotherapy consisted of 45 Gy (1.8 Gy per fraction) to the pelvic lymph nodes with a concomitant 22.5 Gy intensity-modulated radiotherapy boost to the prostate, for a total of 67.5 Gy (2.7 Gy per fraction) in 25 fractions over 5 weeks. Daily image guidance was performed using three gold seed fiducials. Quality of life was measured using the Expanded Prostate Cancer Index Composite (EPIC), a validated tool that assesses four primary domains (urinary, bowel, sexual, and hormonal). Results: From 2004 to 2007, 97 patients were treated. Median follow-up was 39 months. Compared with baseline, at 24 months there was no statistically significant change in the mean urinary domain score (p = 0.99), whereas there were decreases in the bowel (p < 0.01), sexual (p < 0.01), and hormonal (p < 0.01) domains. The proportion of patients reporting a clinically significant difference in EPIC urinary, bowel, sexual, and hormonal scores at 24 months was 27%, 31%, 55%, and 60%, respectively. However, moderate and severe distress related to these symptoms was minimal, with increases of only 3% and 5% in the urinary and bowel domains, respectively. Conclusions: Hypofractionated radiotherapy combined with long-term androgen deprivation therapy was well tolerated. Although there were modest rates of clinically significant patient-reported urinary and bowel toxicity, most of this caused only mild distress, and moderate and severe effects on QOL were limited. Additional follow-up is ongoing to characterize long-term QOL.

  11. Simultaneous integrated boost intensity-modulated radiotherapy in esophageal carcinoma. Early results of a phase II study

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wei-Wei [Fudan University, Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Shanghai (China); Shanghai Jiao Tong University Affiliated Sixth People' s Hospital, Department of Radiation Oncology, Shanghai (China); Zhu, Zheng-Fei; Zhao, Kuai-Le; Mao, Jing-Fang; Wu, Kai-Liang; Yang, Huan-Jun; Fan, Min; Zhao, Sen [Fudan University, Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Shanghai (China); Fu, Xiao-Long [Fudan University Cancer Hospital, Department of Radiation Oncology, Shanghai (China); Fudan University, Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Shanghai (China); Welsh, James [The University of Texas MD Anderson Cancer Center, Departments of Radiation Oncology, Houston, Texas (United States)

    2014-11-15

    The safety and efficacy of using simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) for patients with esophageal squamous cell carcinoma were evaluated in a single-institution phase II setting. Between June 2007 and October 2009, 45 patients underwent concurrent chemoradiotherapy (n = 27) or radiotherapy alone (n = 18). Two planning target volumes (PTV) were defined for the SIB: PTV{sub C} and PTV{sub G}, with prescribed doses of 50.4 Gy to the PTV{sub C} (1.8 Gy/fraction) and 63 Gy to the PTV{sub G} (2.25 Gy/fraction), both given in 28 fractions. At a median follow-up interval of 20.3 months, the 3-year overall survival (OS) and progression-free survival (PFS) rates were 42.2 and 40.7 %, respectively. The median overall survival time was 21 months; locoregional control rates were 83.3 % at 1 year and 67.5 % at 3 years. According to CTCAE (version 3.0) criteria, none of the patients developed grade 4-5 toxicity. The most common grade 2 and 3 radiation-related toxicity was radiation esophagitis, occurring in 64 % of all patients (but only 13 % as grade 3). No patient developed grade > 2 pulmonary complications. SIB-IMRT is a feasible therapeutic approach for esophageal carcinoma patients and provides encouraging locoregional control with a low toxicity profile. Further investigations should focus on dose escalation and optimization of the combination with systemic therapies. (orig.) [German] Die Wirksamkeit und Effektivitaet einer intensitaetsmodulierten Radiotherapie mit einem simultan integrierten Boost (SIB-IMRT) fuer Patienten mit Oesophaguskarzinom wurde in einer Single-Institution-Phase-II-Studie bewertet. Zwischen Juni 2007 und Oktober 2009 wurden 45 Patienten mit einer simultanen Radiochemotherapie (n = 27) oder einer alleinigen Strahlentherapie (n = 18) behandelt. Zwei Planungszielvolumen (PTV) wurden fuer die SIB definiert: PTV{sub C} und PTV{sub G}, mit vorgeschriebenen Dosen von 50,4 Gy fuer PTV{sub C} (1,8 Gy/Fraktion) und 63 Gy

  12. Serial tomotherapy vs. MLC-IMRT (Multileaf Collimator Intensity Modulated Radiotherapy) for simultaneous boost treatment large intracerebral lesions

    International Nuclear Information System (INIS)

    Introduction: Recent data suggest that a radiosurgery boost treatment for up to three brain metastases in addition to whole brain radiotherapy (WBRT) is beneficial. Sequential treatment of multiple metastatic lesions is time-consuming and optimal normal tissue sparing is not trivial for larger metastases when separate plans are created and are only superimposed afterwards. Sequential Tomotherapy with noncoplanar arcs and Multi-field IMRT may streamline the process and enable easy simultaneous treatment. We compared plans for 2-3 intracerebral targets calculated with Intensity Modulated Radiotherapy (IMRT) based on treatment with MLC or sequential Tomotherapy using the Peacock-System. Treatment time was not to exceed 90 min on a linac with standart dose rate. MIMiC plans without treatment-time restrictions were created as a benchmark. Materials and methods: Calculations are based on a Siemens KD2 linac with a dose rate of 200 MU/min. Step-and-Shoot IMRT is performed with a standard MLC (2 x 29 leaves, 1 cm), serial Tomotherapy with the Multivane-Collimator MIMiC (NOMOS Inc. USA). Treatment plans are created with Corvus 5.0. To create plans with good conformity we chose a noncoplanar beam- and arc geometry for each approach (IMRT 4-, MIMiC 5-couch angles). The benchmark MIMiC plans with maximally steep dose gradients had 9 couch angles. For plan comparison reasons, 10Gy were prescribed to 90% of the PTV. Steepness of dose gradients, homogeneity and conformity were assessed by the following parameters: Volume encompassed by certain isodoses outside the target as well as homogeneity and conformity as indicated by Homogeneity- and Conformity-Index. Results: Plans without treatment-time restrictions had slightest dose to organ at risk (OAR), normal tissue and least Conformity-index. MIMiC- and MLC-IMRT based plans can be treated within the intended period of 90 min, all plans met the required dose. MLC based plans resulted in higher dose to organs at risk (OAR) and dose

  13. Feasibility and efficacy of simultaneous integrated boost intensity-modulated radiation therapy in patients with limited-disease small cell lung cancer

    OpenAIRE

    Han, Dan; QIN, Qin; Hao, Shaoyu; Huang, Wei; Wei, Yumei; Zhang, Zicheng; Wang, Zhongtang; LI, BAOSHENG

    2014-01-01

    Purpose To evaluate the feasibility and efficacy of simultaneous integrated boost intensity-modulated radiation therapy (SIB-IMRT) in patients with limited-disease small-cell lung cancer (LD-SCLC). Methods Patients with LD-SCLC were treated with SIB-IMRT within 1 week after completion of 2 cycles of induction chemotherapy. Then 2-4 cycles of adjuvant chemotherapy were administered within 1 week after SIB-IMRT. Irradiation was given accelerated hyper-fractionated with the prescribed dose 57Gy ...

  14. Simultaneous Integrated Boost Using Intensity-Modulated Radiotherapy Compared With Conventional Radiotherapy in Patients Treated With Concurrent Carboplatin and 5-Fluorouracil for Locally Advanced Oropharyngeal Carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Clavel, Sebastien, E-mail: sebastien.clavel@umontreal.ca [Department of Radiation Oncology, Centre Hospitalier de l' Universite de Montreal, Montreal, QC (Canada); Nguyen, David H.A.; Fortin, Bernard [Department of Radiation Oncology, Hopital Maisonneuve-Rosemont, Montreal, QC (Canada); Despres, Philippe [Department of Radiation Oncology, Centre Hospitalier de l' Universite de Montreal, Montreal, QC (Canada); Khaouam, Nader [Department of Radiation Oncology, Hopital Maisonneuve-Rosemont, Montreal, QC (Canada); Donath, David [Department of Radiation Oncology, Centre Hospitalier de l' Universite de Montreal, Montreal, QC (Canada); Soulieres, Denis [Department of Medical Oncology, Centre Hospitalier de l' Universite de Montreal, Montreal, QC (Canada); Guertin, Louis [Department of Head and Neck Surgery, Centre Hospitalier de l' Universite de Montreal, Montreal, QC (Canada); Nguyen-Tan, Phuc Felix [Department of Radiation Oncology, Hopital Maisonneuve-Rosemont, Montreal, QC (Canada)

    2012-02-01

    Purpose: To compare, in a retrospective study, the toxicity and efficacy of simultaneous integrated boost using intensity-modulated radiotherapy (IMRT) vs. conventional radiotherapy (CRT) in patients treated with concomitant carboplatin and 5-fluorouracil for locally advanced oropharyngeal cancer. Methods and Materials: Between January 2000 and December 2007, 249 patients were treated with definitive chemoradiation. One hundred patients had 70 Gy in 33 fractions using IMRT, and 149 received CRT at 70 Gy in 35 fractions. Overall survival, disease-free survival, and locoregional control were estimated using the Kaplan-Meier method. Results: Median follow-up was 42 months. Three-year actuarial rates for locoregional control, disease-free survival, and overall survival were 95.1% vs. 84.4% (p = 0.005), 85.3% vs. 69.3% (p = 0.001), and 92.1% vs. 75.2% (p < 0.001) for IMRT and CRT, respectively. The benefit of the radiotherapy regimen on outcomes was also observed with a Cox multivariate analysis. Intensity-modulated radiotherapy was associated with less acute dermatitis and less xerostomia at 6, 12, 24, and 36 months. Conclusions: This study suggests that simultaneous integrated boost using IMRT is associated with favorable locoregional control and survival rates with less xerostomia and acute dermatitis than CRT when both are given concurrently with chemotherapy.

  15. Dosimetric benefit of DMLC tracking for conventional and sub-volume boosted prostate intensity-modulated arc radiotherapy

    DEFF Research Database (Denmark)

    Pommer, Tobias; Falk, Marianne; Poulsen, Per Rugaard;

    2013-01-01

    This study investigated the dosimetric impact of uncompensated motion and motion compensation with dynamic multileaf collimator (DMLC) tracking for prostate intensity modulated arc therapy. Two treatment approaches were investigated; a conventional approach with a uniform radiation dose to the ta...... to no tracking for target motion >3 mm, with the DMLC tracking distributions showing generally good agreement between the planned and delivered doses.......This study investigated the dosimetric impact of uncompensated motion and motion compensation with dynamic multileaf collimator (DMLC) tracking for prostate intensity modulated arc therapy. Two treatment approaches were investigated; a conventional approach with a uniform radiation dose...... done with and without DMLC tracking on a linear acceleration with a high-resolution MLC. A cylindrical phantom containing two orthogonal diode arrays was used for dosimetry. A motion platform reproduced six patient-derived prostate motion traces, with the average displacement ranging from 1.0 to 8.9 mm...

  16. Phase I Trial of Preoperative Hypofractionated Intensity-Modulated Radiotherapy with Incorporated Boost and Oral Capecitabine in Locally Advanced Rectal Cancer

    International Nuclear Information System (INIS)

    Purpose: To determine the safety and efficacy of preoperative hypofractionated radiotherapy using intensity-modulated radiotherapy (IMRT) and an incorporated boost with concurrent capecitabine in patients with locally advanced rectal cancer. Methods and Materials: The eligibility criteria included adenocarcinoma of the rectum, T3-T4 and/or N1-N2 disease, performance status 0 or 1, and age ≥18 years. Photon IMRT and an incorporated boost were used to treat the whole pelvis to 45 Gy and the gross tumor volume plus 2 cm to 55 Gy in 25 treatments within 5 weeks. The study was designed to escalate the dose to the gross tumor volume in 5-Gy increments in 3-patient cohorts. Capecitabine was given orally 825 mg/m2 twice daily for 7 days each week during RT. The primary endpoint was the maximal tolerated radiation dose, and the secondary endpoints were the pathologic response and quality of life. Results: Eight patients completed RT at the initial dose level of 55 Gy. The study was discontinued because of toxicity-six Grade 3 toxicities occurred in 3 (38%) of 8 patients. All patients went on to definitive surgical resection, and no patient had a pathologically complete response. Conclusion: This regimen, using hypofractionated RT with an incorporated boost, had unacceptable toxicity despite using standard doses of capecitabine and IMRT. Additional research is needed to determine whether IMRT is able to reduce the side effects during and after pelvic RT with conventional dose fractionation

  17. Five-year Local Control in a Phase II Study of Hypofractionated Intensity Modulated Radiation Therapy With an Incorporated Boost for Early Stage Breast Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Freedman, Gary M., E-mail: Gary.Freedman@uphs.upenn.edu [Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania (United States); Anderson, Penny R. [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania (United States); Bleicher, Richard J. [Department of Surgical Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania (United States); Litwin, Samuel; Li Tianyu [Department of Biostatistics, Fox Chase Cancer Center, Philadelphia, Pennsylvania (United States); Swaby, Ramona F. [Department of Medical Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania (United States); Ma, Chang-Ming Charlie; Li Jinsheng [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania (United States); Sigurdson, Elin R. [Department of Surgical Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania (United States); Watkins-Bruner, Deborah [School of Nursing, Emory University, Atlanta, Georgia (United States); Morrow, Monica [Department of Surgical Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Goldstein, Lori J. [Department of Medical Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania (United States)

    2012-11-15

    Purpose: Conventional radiation fractionation of 1.8-2 Gy per day for early stage breast cancer requires daily treatment for 6-7 weeks. We report the 5-year results of a phase II study of intensity modulated radiation therapy (IMRT), hypofractionation, and incorporated boost that shortened treatment time to 4 weeks. Methods and Materials: The study design was phase II with a planned accrual of 75 patients. Eligibility included patients aged {>=}18 years, Tis-T2, stage 0-II, and breast conservation. Photon IMRT and an incorporated boost was used, and the whole breast received 2.25 Gy per fraction for a total of 45 Gy, and the tumor bed received 2.8 Gy per fraction for a total of 56 Gy in 20 treatments over 4 weeks. Patients were followed every 6 months for 5 years. Results: Seventy-five patients were treated from December 2003 to November 2005. The median follow-up was 69 months. Median age was 52 years (range, 31-81). Median tumor size was 1.4 cm (range, 0.1-3.5). Eighty percent of tumors were node negative; 93% of patients had negative margins, and 7% of patients had close (>0 and <2 mm) margins; 76% of cancers were invasive ductal type: 15% were ductal carcinoma in situ, 5% were lobular, and 4% were other histology types. Twenty-nine percent of patients 29% had grade 3 carcinoma, and 20% of patients had extensive in situ carcinoma; 11% of patients received chemotherapy, 36% received endocrine therapy, 33% received both, and 20% received neither. There were 3 instances of local recurrence for a 5-year actuarial rate of 2.7%. Conclusions: This 4-week course of hypofractionated radiation with incorporated boost was associated with excellent local control, comparable to historical results of 6-7 weeks of conventional whole-breast fractionation with sequential boost.

  18. Comparison of long-term survival and toxicity of simultaneous integrated boost vs conventional fractionation with intensity-modulated radiotherapy for the treatment of nasopharyngeal carcinoma

    Directory of Open Access Journals (Sweden)

    Tao HM

    2016-03-01

    Full Text Available Hengmin Tao,1,2 Yumei Wei,1 Wei Huang,1 Xiujuan Gai,1,2 Baosheng Li11Department of 6th Radiation Oncology, Shandong Cancer Hospital and Institute, 2School of Medicine and Life Sciences, Jinan University-Shandong Academy of Medical Sciences, Jinan, People’s Republic of ChinaAim: In recent years, the intensity-modulated radiotherapy with simultaneous integrated boost (IMRT-SIB and intensity-modulated radiotherapy with conventional fractionation (IMRT-CF have been involved in the treatment of nasopharyngeal carcinoma (NPC. However, the potential clinical effects and toxicities are still controversial.Methods: Here, 107 patients with biopsy-proven locally advanced NPC between March 2004 and January 2011 were enrolled in the retrospective study. Among them, 54 patients received IMRT-SIB, and 53 patients received IMRT-CF. Subsequently, overall survival (OS, 5-year progression-free survival (PFS, 5-year locoregional recurrence-free survival (LRFS, and relevant toxicities were analyzed.Results: In the present study, all patients completed the treatment, and the overall median follow-up time was 80 months (range: 8–126 months. The 5-year OS analysis revealed no significant difference between the IMRT-SIB and IMRT-CF groups (80.9% vs 80.5%, P=0.568. In addition, there were also no significant between-group differences in 5-year PFS (73.3% vs 74.4%, P=0.773 and 5-year LRFS (88.1% vs 90.8%, P=0.903. Notably, the dose to critical organs (spinal cord, brainstem, and parotid gland in patients treated by IMRT-CF was significantly lower than that in patients treated by IMRT-SIB (all P<0.05.Conclusion: Both IMRT-SIB and IMRT-CF techniques are effective in treating locally advanced NPC, with similar OS, PFS, and LRFS. However, IMRT-CF has more advantages than IMRT-SIB in protecting spinal cord, brainstem, and parotid gland from acute and late toxicities, such as xerostomia. Further prospective study is warranted to confirm our findings.Keywords: intensity-modulated

  19. Preoperative concomitant boost intensity-modulated radiotherapy with oral capecitabine in locally advanced mid-low rectal cancer: A phase II trial

    International Nuclear Information System (INIS)

    Purpose: We aimed to assess the safety and efficacy of preoperative intensity-modulated radiotherapy (IMRT) with oral capecitabine in patients with locally advanced mid-low rectal cancer using a concomitant boost technique. Materials and methods: Patients with resectable locally advanced mid-low rectal cancer (node-negative ⩾T3 or any node-positive tumor) were eligible. The eligible patients received IMRT to 2 dose levels simultaneously (50.6 and 41.8 Gy in 22 fractions) with concurrent capecitabine 825 mg/m2 twice daily 5 days/week. The primary end point included toxicity, postoperative complication, and pathological complete response rate (ypCR). The secondary endpoints included local recurrence rate, progression-free survival (PFS), and overall survival (OS). Results: Sixty-three eligible patients were enrolled; five patients did not undergo surgery. Of the 58 patients evaluable for pathologic response, the ypCR rate was 31.0% (95% CI 19.1–42.9). Grade 3 toxicities included diarrhea (9.5%), radiation dermatitis (3.2%), and neutropenia (1.6%). There was no Grade 4 toxicity reported. Four (6.9%) patients developed postoperative complications. Two-year local recurrence rate, PFS, and OS were 5.7%, 90.5%, and 96.0%, respectively. Conclusions: The design of preoperative concurrent boost IMRT with oral capecitabine could achieve high rate of ypCR with an acceptable toxicity profile.

  20. Comparison of long-term survival and toxicity of simultaneous integrated boost vs conventional fractionation with intensity-modulated radiotherapy for the treatment of nasopharyngeal carcinoma

    Science.gov (United States)

    Tao, Hengmin; Wei, Yumei; Huang, Wei; Gai, Xiujuan; Li, Baosheng

    2016-01-01

    Aim In recent years, the intensity-modulated radiotherapy with simultaneous integrated boost (IMRT-SIB) and intensity-modulated radiotherapy with conventional fractionation (IMRT-CF) have been involved in the treatment of nasopharyngeal carcinoma (NPC). However, the potential clinical effects and toxicities are still controversial. Methods Here, 107 patients with biopsy-proven locally advanced NPC between March 2004 and January 2011 were enrolled in the retrospective study. Among them, 54 patients received IMRT-SIB, and 53 patients received IMRT-CF. Subsequently, overall survival (OS), 5-year progression-free survival (PFS), 5-year locoregional recurrence-free survival (LRFS), and relevant toxicities were analyzed. Results In the present study, all patients completed the treatment, and the overall median follow-up time was 80 months (range: 8–126 months). The 5-year OS analysis revealed no significant difference between the IMRT-SIB and IMRT-CF groups (80.9% vs 80.5%, P=0.568). In addition, there were also no significant between-group differences in 5-year PFS (73.3% vs 74.4%, P=0.773) and 5-year LRFS (88.1% vs 90.8%, P=0.903). Notably, the dose to critical organs (spinal cord, brainstem, and parotid gland) in patients treated by IMRT-CF was significantly lower than that in patients treated by IMRT-SIB (all Pxerostomia. Further prospective study is warranted to confirm our findings. PMID:27099518

  1. Simultaneous integrated boost radiotherapy for bilateral breast: a treatment planning and dosimetric comparison for volumetric modulated arc and fixed field intensity modulated therapy

    OpenAIRE

    Vanetti Eugenio; Fogliata Antonella; Clivio Alessandro; Nicolini Giorgia; Cozzi Luca

    2009-01-01

    Abstract Purpose A study was performed comparing dosimetric characteristics of volumetric modulated arcs (RapidArc, RA) and fixed field intensity modulated therapy (IMRT) on patients with bilateral breast carcinoma. Materials and methods Plans for IMRT and RA, were optimised for 10 patients prescribing 50 Gy to the breast (PTVII, 2.0 Gy/fraction) and 60 Gy to the tumour bed (PTVI, 2.4 Gy/fraction). Objectives were: for PTVs V90%>95%, Dmax

  2. Intensity-Modulated Radiotherapy as Primary Therapy for Prostate Cancer: Report on Acute Toxicity After Dose Escalation With Simultaneous Integrated Boost to Intraprostatic Lesion

    International Nuclear Information System (INIS)

    Purpose: To report on the acute toxicity of a third escalation level using intensity-modulated radiotherapy for prostate cancer (PCa) and the acute toxicity resulting from delivery of a simultaneous integrated boost (SIB) to an intraprostatic lesion (IPL) detected on magnetic resonance imaging (MRI), with or without spectroscopy. Methods and Materials: Between January 2002 and March 2007, we treated 230 patients with intensity-modulated radiotherapy to a third escalation level as primary therapy for prostate cancer. If an IPL (defined by MRI or MRI plus spectroscopy) was present, a SIB was delivered to the IPL. To report on acute toxicity, patients were seen weekly during treatment and 1 and 3 months after treatment. Toxicity was scored using the Radiation Therapy Oncology Group toxicity scale, supplemented by an in-house-developed scoring system. Results: The median dose to the planning target volume was 78 Gy. An IPL was found in 118 patients. The median dose to the MRI-detected IPL and MRI plus spectroscopy-detected IPL was 81 Gy and 82 Gy, respectively. No Grade 3 or 4 acute gastrointestinal toxicity developed. Grade 2 acute gastrointestinal toxicity was present in 26 patients (11%). Grade 3 genitourinary toxicity was present in 15 patients (7%), and 95 patients developed Grade 2 acute genitourinary toxicity (41%). No statistically significant increase was found in Grade 2-3 acute gastrointestinal or genitourinary toxicity after a SIB to an IPL. Conclusion: The results of our study have shown that treatment-induced acute toxicity remains low when intensity-modulated radiotherapy to 80 Gy as primary therapy for prostate cancer is used. In addition, a SIB to an IPL did not increase the severity or incidence of acute toxicity

  3. Whole brain radiotherapy plus simultaneous in-field boost with image guided intensity-modulated radiotherapy for brain metastases of non-small cell lung cancer

    International Nuclear Information System (INIS)

    Whole brain radiotherapy (WBRT) plus sequential focal radiation boost is a commonly used therapeutic strategy for patients with brain metastases. However, recent reports on WBRT plus simultaneous in-field boost (SIB) also showed promising outcomes. The objective of present study is to retrospectively evaluate the efficacy and toxicities of WBRT plus SIB with image guided intensity-modulated radiotherapy (IG-IMRT) for inoperable brain metastases of NSCLC. Twenty-nine NSCLC patients with 87 inoperable brain metastases were included in this retrospective study. All patients received WBRT at a dose of 40 Gy/20 f, and SIB boost with IG-IMRT at a dose of 20 Gy/5 f concurrent with WBRT in the fourth week. Prior to each fraction of IG-IMRT boost, on-line positioning verification and correction were used to ensure that the set-up errors were within 2 mm by cone beam computed tomography in all patients. The one-year intracranial control rate, local brain failure rate, and distant brain failure rate were 62.9%, 13.8%, and 19.2%, respectively. The two-year intracranial control rate, local brain failure rate, and distant brain failure rate were 42.5%, 30.9%, and 36.4%, respectively. Both median intracranial progression-free survival and median survival were 10 months. Six-month, one-year, and two-year survival rates were 65.5%, 41.4%, and 13.8%, corresponding to 62.1%, 41.4%, and 10.3% of intracranial progression-free survival rates. Patients with Score Index for Radiosurgery in Brain Metastases (SIR) >5, number of intracranial lesions <3, and history of EGFR-TKI treatment had better survival. Three lesions (3.45%) demonstrated radiation necrosis after radiotherapy. Grades 2 and 3 cognitive impairment with grade 2 radiation leukoencephalopathy were observed in 4 (13.8%) and 4 (13.8%) patients. No dosimetric parameters were found to be associated with these late toxicities. Patients received EGFR-TKI treatment had higher incidence of grades 2–3 cognitive impairment with grade

  4. Long-term results of a study using individualized planning target volumes for hypofractionated intensity-modulated radiotherapy boost for prostate cancer

    International Nuclear Information System (INIS)

    This is the final report of a prospective phase I study which evaluated the feasibility, toxicities, and biochemical control in prostate cancer patients treated with a hypofractionated boost utilizing a fiducial marker-based daily image guidance strategy and small patient-specific PTV margins. Low- and intermediate-risk prostate cancer patients underwent transperineal ultrasound-guided implantation of three gold fiducial markers and were treated with three-dimensional conformal radiotherapy to 42 Gy (2 Gy/day). During the first nine fractions of treatment, pre- and post-treatment electronic portal imaging was performed to calculate intrafraction prostate motion. Patient-specific PTV margins were derived and a 30 Gy (3 Gy/day) intensity modulated radiotherapy boost was delivered (Total dose = 72 Gy in 31 fractions; EQD2 = 81 Gy, α/β = 1.4). Thirty-three patients completed treatment and were followed for a median of 7.2 years (range, 1.2 – 9.5). Seven patients (21%) developed Radiation Therapy Oncology Group (RTOG) late grade 2 GI toxicity and 1 patient (3%) developed late grade 2 GU toxicity. No patients developed late grade 3 GI or GU toxicity. To date, nine patients developed PSA relapse according to the Phoenix criteria. The actuarial five, seven and nine year biochemical control (BC) rates were 87% (95% confidence interval: 69–95), 77% (95% confidence interval: 56–89) and 66% (95% confidence interval: 42–82). Our study demonstrates that the use of prostate fiducial markers in combination with a daily online image guidance protocol permits reduced, patient-specific PTV margins in a hypofractionated treatment scheme. This treatment planning and delivery strategy was well tolerated in the intermediate time frame. The use of very small PTV margins did not result in excessive failures when compared to other radiation regimens of similar radiobiological intensity

  5. Preoperative intensity-modulated and image-guided radiotherapy with a simultaneous integrated boost in locally advanced rectal cancer: Report on late toxicity and outcome

    International Nuclear Information System (INIS)

    Background and purpose: The addition of chemotherapy to preoperative radiotherapy has been established as the standard of care for patients with cT3-4 rectal cancer. As an alternative strategy, we explored intensity-modulated and image-guided radiotherapy (IMRT–IGRT) with a simultaneous integrated boost (SIB) in a prospective phase II study. Here, we report outcome and late toxicity after a median follow-up of 54 months. Methods and materials: A total of 108 patients were treated preoperatively with IMRT–IGRT, delivering a dose of 46 Gy in fractions of 2 Gy. Patients (n = 57) displaying an anticipated circumferential resection margin (CRM) of less than 2 mm based on magnetic resonance imaging received a SIB to the tumor up to a total dose of 55.2 Gy. Results: The absolute incidence of grade ⩾3 late gastrointestinal and urinary toxicity was 9% and 4%, respectively, with a 13% rate of any grade ⩾3 late toxicity. The actuarial 5-year local control (LC), progression-free survival (PFS) and overall survival (OS) were 97%, 57%, and 68%. On multivariate analysis, R1 resection and pN2 disease were associated with significantly impaired OS. Conclusions: The use of preoperative IMRT–IGRT with a SIB resulted in a high 5-year LC rate and non-negligible late toxicity

  6. Focal dose escalation using FDG-PET-guided intensity-modulated radiation therapy boost for postoperative local recurrent rectal cancer: a planning study with comparison of DVH and NTCP

    International Nuclear Information System (INIS)

    To evaluate the safety of focal dose escalation to regions with standardized uptake value (SUV) >2.0 using intensity-modulated radiation therapy (IMRT) by comparison of radiotherapy plans using dose-volume histograms (DVHs) and normal tissue complication probability (NTCP) for postoperative local recurrent rectal cancer First, we performed conventional radiotherapy with 40 Gy/20 fr. (CRT 40 Gy) for 12 patients with postoperative local recurrent rectal cancer, and then we performed FDG-PET/CT radiotherapy planning for those patients. We defined the regions with SUV > 2.0 as biological target volume (BTV) and made three boost plans for each patient: 1) CRT boost plan, 2) IMRT without dose-painting boost plan, and 3) IMRT with dose-painting boost plan. The total boost dose was 20 Gy. In IMRT with dose-painting boost plan, we increased the dose for BTV+5 mm by 30% of the prescribed dose. We added CRT boost plan to CRT 40 Gy (summed plan 1), IMRT without dose-painting boost plan to CRT 40 Gy (summed plan 2) and IMRT with dose-painting boost plan to CRT 40 Gy (summed plan 3), and we compared those plans using DVHs and NTCP. Dmean of PTV-PET and that of PTV-CT were 26.5 Gy and 21.3 Gy, respectively. V50 of small bowel PRV in summed plan 1 was significantly higher than those in other plans ((summed plan 1 vs. summed plan 2 vs. summed plan 3: 47.11 ± 45.33 cm3 vs. 40.63 ± 39.13 cm3 vs. 41.25 ± 39.96 cm3(p < 0.01, respectively)). There were no significant differences in V30, V40, V60, Dmean or NTCP of small bowel PRV. FDG-PET-guided IMRT can facilitate focal dose-escalation to regions with SUV above 2.0 for postoperative local recurrent rectal cancer

  7. Intensity-Modulated Radiotherapy with a Simultaneous Integrated Boost Combined with Chemotherapy in Stages III-IV Hypopharynx-Larynx Cancer: Treatment Compliance and Clinical Outcomes

    Directory of Open Access Journals (Sweden)

    Giovanni Franchin

    2014-01-01

    Full Text Available Objectives. Retrospective review of our experience using intensity-modulated radiotherapy with simultaneous integrated boost (SIB-IMRT combined with chemotherapy as the primary treatment of locoregionally advanced larynx and hypopharynx cancers. Materials and Methods. Between September 2008 and June 2012, 60 patients (26 with larynx and 34 hypopharynx cancers were treated. Our policy was to offer SIB-IMRT plus concurrent cisplatin to patients affected by larynx cancer stage T3N0-N1 and NCT with TPF (docetaxel/cisplatin/fluorouracil followed by SIB-IMRT to patients with larynx cancer stage T2-4N2-3 or hypopharynx cancer T2-4N0-3. SIB-IMRT consisted in a total dose of 70.95 Gy (2.15 Gy/fraction, 5 fractions/week to the gross primary and nodal disease and differentiated dosages for high risk and low risk nodal regions. Results. Complete remission was achieved in 53/60 (88% of patients. At a median follow up of 31 months (range 9–67, the rate of overall survival and locoregional control with functional larynx at 3 years were 68% and 60%, respectively. T stage (T1–3 versus T4 resulted in being significant for predicting 3-year freedom from relapse (it was 69% and 35%, resp., for T1–T3 and T4 tumors; P=0.04, while site of primary disease (larynx versus hypopharynx was not significant (P=0.35. Conclusion. Our results indicated that combining SIB-IMRT with induction chemotherapy or concurrent chemotherapy is an effective treatment strategy for organ preservation in advanced larynx/hypopharynx cancer.

  8. Intensity-modulated pelvic radiation therapy and simultaneous integrated boost to the prostate area in patients with high-risk prostate cancer: a preliminary report of disease control.

    Science.gov (United States)

    Saracino, Biancamaria; Petrongari, Maria Grazia; Marzi, Simona; Bruzzaniti, Vicente; Sara, Gomellini; Arcangeli, Stefano; Arcangeli, Giorgio; Pinnarò, Paola; Giordano, Carolina; Ferraro, Anna Maria; Strigari, Lidia

    2014-10-01

    The aim of the study was to report the clinical results in patients with high-risk prostate cancer treated with pelvic intensity-modulated radiation therapy (IMRT) and simultaneous integrated boost (SIB) to the prostate area. A total of 110 patients entered our study, 37 patients presented with localized prostate cancer and radiological evidence of node metastases or ≥15% estimated risk of lymph node (LN) involvement, while 73 patients underwent postoperative adjuvant or salvage irradiation for biochemical or residual/recurrent disease, LN metastases, or high risk of harboring nodal metastases. All patients received androgen deprivation therapy (ADT) for 2 years. The median follow-up was 56.5 months. For the whole patient group, the 3- and 5-year freedom from biochemical failure were 82.6% and 74.6%, respectively, with a better outcome in patients treated with radical approach. The 3- and 5-year freedom from local failure were 94.4% and 90.2%, respectively, while the 3- and 5-year distant metastasis-free survival were 87.8% and 81.7%, respectively. For all study patients, the rate of freedom from G2 acute rectal, intestinal, and urinary toxicities was 60%, 77%, and 61%, respectively. There was no G3 acute toxicity, ≥G2 late intestinal toxicity, or G3 late urinary or rectal toxicity. The 3- and 5-year ≥G2 freedom from late rectal toxicity rate were 98% and 95%, respectively, while the 3- and 5-year ≥G2 freedom from late urinary toxicity rate were 95% and 88%, respectively. The study concludes that pelvic IMRT and SIB to the prostatic area in association with 2-year ADT was a well-tolerated technique, providing high disease control in patients with prostate cancer requiring LN treatment. PMID:24976538

  9. Intensity-modulated pelvic radiation therapy and simultaneous integrated boost to the prostate area in patients with high-risk prostate cancer: a preliminary report of disease control

    International Nuclear Information System (INIS)

    The aim of the study was to report the clinical results in patients with high-risk prostate cancer treated with pelvic intensity-modulated radiation therapy (IMRT) and simultaneous integrated boost (SIB) to the prostate area. A total of 110 patients entered our study, 37 patients presented with localized prostate cancer and radiological evidence of node metastases or ≥15% estimated risk of lymph node (LN) involvement, while 73 patients underwent postoperative adjuvant or salvage irradiation for biochemical or residual/recurrent disease, LN metastases, or high risk of harboring nodal metastases. All patients received androgen deprivation therapy (ADT) for 2 years. The median follow-up was 56.5 months. For the whole patient group, the 3- and 5-year freedom from biochemical failure were 82.6% and 74.6%, respectively, with a better outcome in patients treated with radical approach. The 3- and 5-year freedom from local failure were 94.4% and 90.2%, respectively, while the 3- and 5-year distant metastasis-free survival were 87.8% and 81.7%, respectively. For all study patients, the rate of freedom from G2 acute rectal, intestinal, and urinary toxicities was 60%, 77%, and 61%, respectively. There was no G3 acute toxicity, ≥G2 late intestinal toxicity, or G3 late urinary or rectal toxicity. The 3- and 5-year ≥G2 freedom from late rectal toxicity rate were 98% and 95%, respectively, while the 3- and 5-year ≥G2 freedom from late urinary toxicity rate were 95% and 88%, respectively. The study concludes that pelvic IMRT and SIB to the prostatic area in association with 2-year ADT was a well-tolerated technique, providing high disease control in patients with prostate cancer requiring LN treatment

  10. Fully Automated Simultaneous Integrated Boosted-Intensity Modulated Radiation Therapy Treatment Planning Is Feasible for Head-and-Neck Cancer: A Prospective Clinical Study

    Energy Technology Data Exchange (ETDEWEB)

    Wu Binbin, E-mail: binbin.wu@gunet.georgetown.edu [Department of Radiation Oncology and Molecular Radiation Science, Johns Hopkins University, Baltimore, Maryland (United States); Department of Radiation Medicine, Georgetown University Hospital, Washington, DC (United States); McNutt, Todd [Department of Radiation Oncology and Molecular Radiation Science, Johns Hopkins University, Baltimore, Maryland (United States); Zahurak, Marianna [Department of Oncology Biostatistics, Johns Hopkins University, Baltimore, Maryland (United States); Simari, Patricio [Autodesk Research, Toronto, ON (Canada); Pang, Dalong [Department of Radiation Medicine, Georgetown University Hospital, Washington, DC (United States); Taylor, Russell [Department of Computer Science, Johns Hopkins University, Baltimore, Maryland (United States); Sanguineti, Giuseppe [Department of Radiation Oncology and Molecular Radiation Science, Johns Hopkins University, Baltimore, Maryland (United States)

    2012-12-01

    Purpose: To prospectively determine whether overlap volume histogram (OVH)-driven, automated simultaneous integrated boosted (SIB)-intensity-modulated radiation therapy (IMRT) treatment planning for head-and-neck cancer can be implemented in clinics. Methods and Materials: A prospective study was designed to compare fully automated plans (APs) created by an OVH-driven, automated planning application with clinical plans (CPs) created by dosimetrists in a 3-dose-level (70 Gy, 63 Gy, and 58.1 Gy), head-and-neck SIB-IMRT planning. Because primary organ sparing (cord, brain, brainstem, mandible, and optic nerve/chiasm) always received the highest priority in clinical planning, the study aimed to show the noninferiority of APs with respect to PTV coverage and secondary organ sparing (parotid, brachial plexus, esophagus, larynx, inner ear, and oral mucosa). The sample size was determined a priori by a superiority hypothesis test that had 85% power to detect a 4% dose decrease in secondary organ sparing with a 2-sided alpha level of 0.05. A generalized estimating equation (GEE) regression model was used for statistical comparison. Results: Forty consecutive patients were accrued from July to December 2010. GEE analysis indicated that in APs, overall average dose to the secondary organs was reduced by 1.16 (95% CI = 0.09-2.33) with P=.04, overall average PTV coverage was increased by 0.26% (95% CI = 0.06-0.47) with P=.02 and overall average dose to the primary organs was reduced by 1.14 Gy (95% CI = 0.45-1.8) with P=.004. A physician determined that all APs could be delivered to patients, and APs were clinically superior in 27 of 40 cases. Conclusions: The application can be implemented in clinics as a fast, reliable, and consistent way of generating plans that need only minor adjustments to meet specific clinical needs.

  11. Long-term outcome and late toxicities of simultaneous integrated boost-intensity modulated radiotherapy in pediatric and adolescent nasopharyngeal carcinoma

    Institute of Scientific and Technical Information of China (English)

    Chang-Juan Tao; Ai-Hua Lin; Jun Ma; Ying Sun; Xu Liu; Ling-Long Tang; Yan-Ping Mao; Lei Chen; Wen-Fei Li; Xiao-Li Yu; Li-Zhi Liu; Rong Zhang

    2013-01-01

    The application of simultaneous integrated boost-intensity modulated radiotherapy (SIB-IMRT) in pediatric and adolescent nasopharyngeal carcinoma (NPC) is underevaluated. This study aimed to evaluate long-term outcome and late toxicities in pediatric and adolescent NPC after SIB-IMRT combined with chemotherapy. Thirty-four patients (aged 8-20 years) with histologically proven, non-disseminated NPC treated with SIB-IMRT were enrol ed in this retrospective study. The disease stage distribution was as fol ows:stage I, 1 (2.9%);stage III, 14 (41.2%);and stage IV, 19 (55.9%). Al patients underwent SIB-IMRT and 30 patients also underwent cisplatin-based chemotherapy. The prescribed dose of IMRT was 64-68 Gy in 29-31 fractions to the nasopharyngeal gross target volume. Within the median fol ow-up of 52 months (range, 9-111 months), 1 patient (2.9%) experienced local recurrence and 4 (11.8%) developed distant metastasis (to the lung in 3 cases and to multiple organs in 1 case). Four patients (11.8%) died due to recurrence or metastasis. The 5-year locoregional relapse-free survival, distant metastasis-free survival, disease-free survival, and overal survival rates were 97.1%, 88.2%, 85.3%, and 88.2%, respectively. The most common acute toxicities were grades 3-4 hematologic toxicities and stomatitis. Of the 24 patients who survived for more than 2 years, 16 (66.7%) and 15 (62.5%) developed grades 1-2 xerostomia and ototoxicity, respectively. Two patients (8.3%) developed grade 3 ototoxicity; no grade 4 toxicities were observed. SIB-IMRT combined with chemotherapy achieves excellent long-term locoregional control in pediatric and adolescent NPC, with mild incidence of late toxicities. Distant metastasis is the predominant mode of failure.

  12. Long-term outcome and late toxicities of simultaneous integrated boost-intensity modulated radiotherapy in pediatric and adolescent nasopharyngeal carcinoma

    Directory of Open Access Journals (Sweden)

    Li-Zhi Liu

    2013-10-01

    Full Text Available The application of simultaneous integrated boost-intensity modulated radiotherapy (SIB-IMRT in pediatric and adolescent nasopharyngeal carcinoma (NPC is underevaluated. This study aimed to evaluate long-term outcome and late toxicities in pediatric and adolescent NPC after SIB-IMRT combined with chemotherapy. Thirty-four patients (aged 8-20 years with histologically proven, non-disseminated NPC treated with SIB-IMRT were enrolled in this retrospective study. The disease stage distribution was as follows: stage I, 1 (2.9%; stage III, 14 (41.2%; and stage IV, 19 (55.9%. All patients underwent SIB-IMRT and 30 patients also underwent cisplatin-based chemotherapy. The prescribed dose of IMRT was 64-68 Gy in 29-31 fractions to the nasopharyngeal gross target volume. Within the median follow-up of 52 months (range, 9-111 months, 1 patient (2.9% experienced local recurrence and 4 (11.8% developed distant metastasis (to the lung in 3 cases and to multiple organs in 1 case. Four patients (11.8% died due to recurrence or metastasis. The 5-year locoregional relapse-free survival, distant metastasis-free survival, disease-free survival, and overall survival rates were 97.1%, 88.2%, 85.3%, and 88.2%, respectively. The most common acute toxicities were grades 3-4 hematologic toxicities and stomatitis. Of the 24 patients who survived for more than 2 years, 16 (66.7% and 15 (62.5% developed grades 1-2 xerostomia and ototoxicity, respectively. Two patients (8.3% developed grade 3 ototoxicity; no grade 4 toxicities were observed. SIB-IMRT combined with chemotherapy achieves excellent long-term locoregional control in pediatric and adolescent NPC, with mild incidence of late toxicities. Distant metastasis is the predominant mode of failure.

  13. Intensity-Modulated Radiotherapy with a Simultaneous Integrated Boost Combined with Chemotherapy in Stages III-IV Hypopharynx-Larynx Cancer: Treatment Compliance and Clinical Outcomes

    International Nuclear Information System (INIS)

    Objectives. Retrospective review of our experience using intensity-modulated radiotherapy with simultaneous integrated boost (SIB-IMRT) combined with chemotherapy as the primary treatment of locoregionally advanced larynx and hypopharynx cancers. Materials and Methods. Between September 2008 and June 2012, 60 patients (26 with larynx and 34 hypopharynx cancers) were treated. Our policy was to offer SIB-IMRT plus concurrent cisplatin to patients affected by larynx cancer stage T3N0-N1 and NCT with TPF (docetaxel/cisplatin/fluorouracil) followed by SIB-IMRT to patients with larynx cancer stage T2-4N2-3 or hypopharynx cancer T2-4N0-3. SIB-IMRT consisted in a total dose of 70.95 Gy (2.15 Gy/fraction, 5 fractions/week) to the gross primary and nodal disease and differentiated dosages for high risk and low risk nodal regions. Results. Complete remission was achieved in 53/60 (88%) of patients. At a median follow up of 31 months (range 9–67), the rate of overall survival and locoregional control with functional larynx at 3 years were 68% and 60%, respectively. T stage (T1–3 versus T4) resulted in being significant for predicting 3-year freedom from relapse (it was 69% and 35%, resp., for T1–T3 and T4 tumors; (Ρ =0.35),while site of primary disease (larynx versus hypopharynx) was not significant (Ρ =0.35). Conclusion. Our results indicated that combining SIB-IMRT with induction chemotherapy or concurrent chemotherapy is an effective treatment strategy for organ preservation in advanced larynx/hypopharynx cancer.

  14. Simultaneous integrated boost radiotherapy for bilateral breast: a treatment planning and dosimetric comparison for volumetric modulated arc and fixed field intensity modulated therapy

    Directory of Open Access Journals (Sweden)

    Vanetti Eugenio

    2009-07-01

    Full Text Available Abstract Purpose A study was performed comparing dosimetric characteristics of volumetric modulated arcs (RapidArc, RA and fixed field intensity modulated therapy (IMRT on patients with bilateral breast carcinoma. Materials and methods Plans for IMRT and RA, were optimised for 10 patients prescribing 50 Gy to the breast (PTVII, 2.0 Gy/fraction and 60 Gy to the tumour bed (PTVI, 2.4 Gy/fraction. Objectives were: for PTVs V90%>95%, Dmax20 Gy Results For PTVII minus PTVI, V90% was 97.8 ± 3.4% for RA and 94.0 ± 3.5% for IMRT (findings are reported as mean ± 1 standard deviation; D5%-D95% (homogeneity was 7.3 ± 1.4 Gy (RA and 11.0 ± 1.1 Gy (IMRT. Conformity index (V95%/VPTVII was 1.10 ± 0.06 (RA and 1.14 ± 0.09 (IMRT. MLD was 20 Gy was 9.7 ± 1.3% (RA and 12.8 ± 2.5% (IMRT on left lung, similar for right lung. Mean dose to heart was 6.0 ± 2.7 Gy (RA and 7.4 ± 2.5 Gy (IMRT. MU resulted in 796 ± 121 (RA and 1398 ± 301 (IMRT; the average measured treatment time was 3.0 ± 0.1 minutes (RA and 11.5 ± 2.0 (IMRT. From pre-treatment dosimetry, % of field area with γ Conclusion RapidArc showed dosimetric improvements with respect to IMRT, delivery parameters confirmed its logistical advantages, pre-treatment dosimetry proved its reliability.

  15. Intensity modulated proton therapy

    OpenAIRE

    Kooy, H. M.; Grassberger, C

    2015-01-01

    Intensity modulated proton therapy (IMPT) implies the electromagnetic spatial control of well-circumscribed “pencil beams” of protons of variable energy and intensity. Proton pencil beams take advantage of the charged-particle Bragg peak—the characteristic peak of dose at the end of range—combined with the modulation of pencil beam variables to create target-local modulations in dose that achieves the dose objectives. IMPT improves on X-ray intensity modulated beams (intensity modulated radio...

  16. Simultaneous integrated boost radiotherapy for bilateral breast: a treatment planning and dosimetric comparison for volumetric modulated arc and fixed field intensity modulated therapy

    International Nuclear Information System (INIS)

    A study was performed comparing dosimetric characteristics of volumetric modulated arcs (RapidArc, RA) and fixed field intensity modulated therapy (IMRT) on patients with bilateral breast carcinoma. Plans for IMRT and RA, were optimised for 10 patients prescribing 50 Gy to the breast (PTVII, 2.0 Gy/fraction) and 60 Gy to the tumour bed (PTVI, 2.4 Gy/fraction). Objectives were: for PTVs V90%>95%, Dmax<107%; Mean lung dose MLD<15 Gy, V20 Gy<22%; heart involvement was to be minimised. The MU and delivery time measured treatment efficiency. Pre-treatment dosimetry was performed using EPID and a 2D-array based methods. For PTVII minus PTVI, V90% was 97.8 ± 3.4% for RA and 94.0 ± 3.5% for IMRT (findings are reported as mean ± 1 standard deviation); D5%-D95% (homogeneity) was 7.3 ± 1.4 Gy (RA) and 11.0 ± 1.1 Gy (IMRT). Conformity index (V95%/VPTVII) was 1.10 ± 0.06 (RA) and 1.14 ± 0.09 (IMRT). MLD was <9.5 Gy for all cases on each lung, V20 Gy was 9.7 ± 1.3% (RA) and 12.8 ± 2.5% (IMRT) on left lung, similar for right lung. Mean dose to heart was 6.0 ± 2.7 Gy (RA) and 7.4 ± 2.5 Gy (IMRT). MU resulted in 796 ± 121 (RA) and 1398 ± 301 (IMRT); the average measured treatment time was 3.0 ± 0.1 minutes (RA) and 11.5 ± 2.0 (IMRT). From pre-treatment dosimetry, % of field area with γ <1 resulted 98.8 ± 1.3% and 99.1 ± 1.5% for RA and IMRT respectively with EPID and 99.1 ± 1.8% and 99.5 ± 1.3% with 2D-array (ΔD = 3% and DTA = 3 mm). RapidArc showed dosimetric improvements with respect to IMRT, delivery parameters confirmed its logistical advantages, pre-treatment dosimetry proved its reliability

  17. A dosimetric comparison of three plans in simultaneous integrated boost intensity-modulated radiotherapy in cervical esophageal carcinoma undergoing prophylactic lymphatic irradiation

    International Nuclear Information System (INIS)

    Objective: To evaluate the optimized simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) plans in cervical esophageal carcinoma underwent prophylactic lymphatic irradiation. Methods: Six patients with cervical esophageal carcinoma were studied.The gross tumor volume (GTV) and clinical target volume (CTV) (including bilateral mid-lower neck and supraclavicular lymph drainage regions, upper mediastinal lymph drainage regions) were delineated on sim-CT images, GTV and CTV were uniformly expanded by 5 mm to create PGTV and PTV. Five fields (5F), 7F and 9F SIB-IMRT plans were designed. The prescribed doses to PGTV and PTV were 66 Gy and 60 Gy in 30 fractions respectively. The parameters of dose-volume histograms in three groups planning were compared. Results: The values of conformity index (CI) of PGTV were 0.56, 0.62 and 0.69 (F =6.22, P<0.01), the V66 with 88.24%, 95.03% and 94.91% (F=4.39, P<0.05) and D95 with 6539.67, 6601.83 and 6602.00 cGy (F=4.46, P<0.05) in 5F, 7F and 9F SIB-IMRT plans. The values of CI, V66 and D95 of PTV were 0.80, 0.85 and 0.87 (F=11.29, P<0.01), with 91.64%, 94.05% and 95.06% (F=4.10, P<0.05) and with 5934.00, 5987.17 and 6006.33 cGy (F=4.01, P<0.05). The values of maximal dose of spinal cord were 4707.17, 4497.83 and 4357.00 cGy (F=11.26, P<0.011) in 5F, 7F and 9F SIB-IMRT plans. The values of all dosimetric parameters about PGTV and PTV were same in 7F and 9F SIB-IMRT plans (all P>0.05). Conclusion: 7F-SIB-IMRT plan is best one scheme for cervical esophageal carcinoma underwent prophylactic lymphatic irradiation. (authors)

  18. Feasibility and efficacy of simultaneous integrated boost intensity-modulated radiation therapy in patients with limited-disease small cell lung cancer

    International Nuclear Information System (INIS)

    To evaluate the feasibility and efficacy of simultaneous integrated boost intensity-modulated radiation therapy (SIB-IMRT) in patients with limited-disease small-cell lung cancer (LD-SCLC). Patients with LD-SCLC were treated with SIB-IMRT within 1 week after completion of 2 cycles of induction chemotherapy. Then 2-4 cycles of adjuvant chemotherapy were administered within 1 week after SIB-IMRT. Irradiation was given accelerated hyper-fractionated with the prescribed dose 57Gy at 1.9Gy twice daily to the gross tumor volume (GTV) , 51Gy at 1.7Gy twice daily to the clinical tumor volume (CTV) and 45Gy at 1.5Gy twice daily to the planning target volume (PTV). The chemotherapy regimen consisted of platinum plus etoposide. Prophylactic cranial radiation (25Gy in 10 fractions) was administered to patients who got complete response (CR) or near complete response (nCR). The primary endpoint of this study was the frequency of grade 3 or higher acute non-hematologic treatment-related toxicities. Secondary end points included objective response, overall survival (OS), progression-free survival (PFS), locoregional recurrence-free survival (LRFS). A cohort of 35 patients were enrolled in the study, the biological equivalent dose (BED) of the GTV in the SIB-IMRT was 59.16Gy. Grade 1, 2, and 3 esophagitis were observed in 11 (31%), 12 (34%), and 6 (17%) patients, respectively; Grade 1 and 2 pneumonitis were observed in 8 (23%) and 4 (11%) patients, respectively. The median OS and PFS of the whole group were 37.7 months and 29.3 months, respectively. The 1- and 2-year OS was 94.1% and 68.5%, respectively. The 1- and 2-year PFS was 76.8% and 40.7%, respectively. The 1- and 2-year LRFS was 87.7% and 73.8%, respectively. SIB-IMRT was feasible and well-tolerated in patients with LD-SCLC, and worth further evaluating in a large prospective clinical trial

  19. SU-E-P-21: Impact of MLC Position Errors On Simultaneous Integrated Boost Intensity-Modulated Radiotherapy for Nasopharyngeal Carcinoma

    International Nuclear Information System (INIS)

    Purpose: To investigate the impact of MLC position errors on simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) for patients with nasopharyngeal carcinoma. Methods: To compare the dosimetric differences between the simulated plans and the clinical plans, ten patients with locally advanced NPC treated with SIB-IMRT were enrolled in this study. All plans were calculated with an inverse planning system (Pinnacle3, Philips Medical System). Random errors −2mm to 2mm),shift errors( 2mm,1mm and 0.5mm) and systematic extension/ contraction errors (±2mm, ±1mm and ±0.5mm) of the MLC leaf position were introduced respectively into the original plans to create the simulated plans. Dosimetry factors were compared between the original and the simulated plans. Results: The dosimetric impact of the random and system shift errors of MLC position was insignificant within 2mm, the maximum changes in D95% of PGTV,PTV1,PTV2 were-0.92±0.51%,1.00±0.24% and 0.62±0.17%, the maximum changes in the D0.1cc of spinal cord and brainstem were 1.90±2.80% and −1.78±1.42%, the maximum changes in the Dmean of parotids were1.36±1.23% and −2.25±2.04%.However,the impact of MLC extension or contraction errors was found significant. For 2mm leaf extension errors, the average changes in D95% of PGTV,PTV1,PTV2 were 4.31±0.67%,4.29±0.65% and 4.79±0.82%, the averaged value of the D0.1cc to spinal cord and brainstem were increased by 7.39±5.25% and 6.32±2.28%,the averaged value of the mean dose to left and right parotid were increased by 12.75±2.02%,13.39±2.17% respectively. Conclusion: The dosimetric effect was insignificant for random MLC leaf position errors up to 2mm. There was a high sensitivity to dose distribution for MLC extension or contraction errors.We should pay attention to the anatomic changes in target organs and anatomical structures during the course,individual radiotherapy was recommended to ensure adaptive doses

  20. Phase II study of induction chemotherapy with TPF followed by radioimmunotherapy with Cetuximab and intensity-modulated radiotherapy (IMRT in combination with a carbon ion boost for locally advanced tumours of the oro-, hypopharynx and larynx - TPF-C-HIT

    Directory of Open Access Journals (Sweden)

    Mavtratzas Athanasios

    2011-05-01

    Full Text Available Abstract Background Long-term locoregional control in locally advanced squamous cell carcinoma of the head and neck (SCCHN remains challenging. While recent years have seen various approaches to improve outcome by intensification of treatment schedules through introduction of novel induction and combination chemotherapy regimen and altered fractionation regimen, patient tolerance to higher treatment intensities is limited by accompanying side-effects. Combined radioimmunotherapy with cetuximab as well as modern radiotherapy techniques such as intensity-modulated radiotherapy (IMRT and carbon ion therapy (C12 are able to limit toxicity while maintaining treatment effects. In order to achieve maximum efficacy with yet acceptable toxicity, this sequential phase II trial combines induction chemotherapy with docetaxel, cisplatin, and 5-FU (TPF followed by radioimmunotherapy with cetuximab as IMRT plus carbon ion boost. We expect this approach to result in increased cure rates with yet manageable accompanying toxicity. Methods/design The TPF-C-HIT trial is a prospective, mono-centric, open-label, non-randomized phase II trial evaluating efficacy and toxicity of the combined treatment with IMRT/carbon ion boost and weekly cetuximab in 50 patients with histologically proven locally advanced SCCHN following TPF induction chemotherapy. Patients receive 24 GyE carbon ions (8 fractions and 50 Gy IMRT (2.0 Gy/fraction in combination with weekly cetuximab throughout radiotherapy. Primary endpoint is locoregional control at 12 months, secondary endpoints are disease-free survival, progression-free survival, overall survival, acute and late radiation effects as well as any adverse events of the treatment as well as quality of life (QoL analyses. Discussion The primary objective of TPF-C-HIT is to evaluate efficacy and toxicity of cetuximab in combination with combined IMRT/carbon ion therapy following TPF induction in locally advanced SCCHN. Trial Registration

  1. Robotic radiosurgery vs. brachytherapy as a boost to intensity modulated radiotherapy for tonsillar fossa and soft palate tumors: the clinical and economic impact of an emerging technology.

    Science.gov (United States)

    Nijdam, W; Levendag, P; Fuller, D; Schulz, R; Prevost, J-B; Noever, I; Uyl-de Groot, C

    2007-12-01

    As a basis for making decisions regarding optimal treatment for patients with tonsillar fossa and soft palate tumors, we conducted a preliminary investigation of costs and quality of life (QoL) for two modalities [brachytherapy (BT) and robotic radiosurgery] used to boost radiation to the primary tumors following external beam radiotherapy. BT was well established in our center; a boost by robotic radiosurgery was begun more recently in patients for whom BT was not technically feasible. Robotic radiosurgery boost treatment has the advantage of being non-invasive and is able to reach tumors in cases where there is deep parapharyngeal tumor extension. A neck dissection was performed for patients with nodal-positive disease. Quality of life (pain and difficulty swallowing) was established in long-term follow-up for patients undergoing BT and over a one-year follow-up in robotic radiosurgery patients. Total hospital costs for both groups were computed. Our results show that efficacy and quality of life at one year are comparable for BT and robotic radiosurgery. Total cost for robotic radiosurgery was found to be less than BT primarily due to the elimination of hospital admission and operating room expenses. Confirmation of robotic radiosurgery treatment efficacy and reduced morbidity in the long term requires further study. Quality of life and cost analyses are critical to Health Technology Assessments (HTA). The present study shows how a preliminary HTA of a new medical technology such as robotic radiosurgery with its typical hypofractionation characteristics might be based on short-term clinical outcomes and assumptions of equivalence. PMID:17994791

  2. Volumetric Arc Therapy and Intensity-Modulated Radiotherapy for Primary Prostate Radiotherapy With Simultaneous Integrated Boost to Intraprostatic Lesion With 6 and 18 MV: A Planning Comparison Study

    International Nuclear Information System (INIS)

    Purpose: The aim of the present study was to compare intensity-modulated radiotherapy (IMRT) with volumetric arc therapy (VMAT), in the treatment of prostate cancer with maximal dose escalation to the intraprostatic lesion (IPL), without violating the organ-at-risk constraints. Additionally, the use of 6-MV photons was compared with 18-MV photons for all techniques. Methods and Materials: A total of 12 consecutive prostate cancer patients with an IPL on magnetic resonance imaging were selected for the present study. Plans were made for three IMRT field setups (three, five, and seven fields) and one VMAT field setup (single arc). First, optimal plans were created for every technique using biologic and physical planning aims. Next, an additional escalation to the IPL was planned as high as possible without violating the planning aims of the first step. Results: No interaction between the technique and photon energy (p = .928) occurred. No differences were found between the 6- and 18-MV photon beams, except for a reduction in the number of monitor units needed for 18 MV (p < .05). All techniques, except for three-field IMRT, allowed for dose escalation to a median dose of ≥93 ± 6 Gy (mean ± standard deviation) to the IPL. VMAT was superior to IMRT for rectal volumes receiving 20-50 Gy (p < .05). Conclusion: VMAT allowed for dose escalation to the IPL with better sparing of the rectum than static three-, five-, and seven-field IMRT setups. High-energy photons had no advantage over low-energy photons.

  3. Serum release boosts sweetness intensity in gels

    NARCIS (Netherlands)

    Sala, G.; Stieger, M.A.; Velde, van de F.

    2010-01-01

    This paper describes the effect of serum release on sweetness intensity in mixed whey protein isolate/gellan gum gels. The impact of gellan gum and sugar concentration on microstructure, permeability, serum release and large deformation properties of the gels was determined. With increasing gellan g

  4. Photovoltaic Simplified Boost Z Source Inverter for Ac Module Applications

    Directory of Open Access Journals (Sweden)

    J. Sam Alaric

    2014-08-01

    Full Text Available This study mainly proposed PV z source boost inverter used to boundary grid or ac module applications. Separate types of converter used for solar system due to its current lagging, here capacitor multiplier based boost converter introduced for maintain the current lagging and voltage gain. Here, the switched inductor z source inverter implemented for grid interface. Proposed z source inverter is controlled by pulse width modulation. A simplified capacitor multiplier controlled by continuous conduction mode, A detailed topology analysis and a generalized discussion are given. The multiplier boost converter has the merits of maintain voltage level and reducing cost and current lagging. Simulation results are implemented and analysis MATLAB software.

  5. Helical intensity-modulated Radiotherapy of the Pelvic Lymph Nodes with Integrated Boost to the Prostate Bed - Initial Results of the PLATIN 3 Trial

    International Nuclear Information System (INIS)

    Adjuvant and salvage radiotherapy of the prostate bed are established treatment options for prostate cancer. While the benefit of an additional radiotherapy of the pelvic lymph nodes is still under debate, the PLATIN 3 prospective phase II clinical trial was initiated to substantiate toxicity data on postoperative IMRT of the pelvic lymph nodes and the prostate bed. From 2009 to 2011, 40 patients with high-risk prostate cancer after prostatectomy with pT3 R0/1 M0 or pT2 R1 M0 or a PSA recurrence and either > 20% risk of lymph node involvement and inadequate lymphadenectomy or pN + were enrolled. Patients received two months of antihormonal treatment (AT) before radiotherapy. AT continuation was mandatory during radiotherapy and was recommended for another two years. IMRT of the pelvic lymph nodes (51.0 Gy) with a simultaneous integrated boost to the prostate bed (68.0 Gy) was performed in 34 fractions. PSA level, prostate-related symptoms and quality of life were assessed at regular intervals for 24 months. Of the 40 patients enrolled, 39 finished treatment as planned. Overall acute toxicity rates were low and no acute grade 3/4 toxicity occurred. Only 22.5% of patients experienced acute grade 2 gastrointestinal (GI) and genitourinary (GU) toxicity. During follow-up, 10.0% late grade 2 GI and 5.0% late grade 2 GU toxicity occurred, and one patient developed late grade 3 proctitis and enteritis. After a median observation time of 24 months the PLATIN 3 trial has shown in 97.5% of all patients sufficient safety and thus met its prospectively defined aims. After a median of 24 months, 34/38 patients were free of a PSA recurrence. Postoperative whole-pelvis IMRT with an integrated boost to the prostate bed can be performed safely and without excessive toxicity. Trial Numbers: ARO 2009–05, ClinicalTrials.gov: http://clinicaltrials.gov/ct2/show/NCT01903408?term

  6. Extended Field Intensity Modulated Radiation Therapy With Concomitant Boost for Lymph Node–Positive Cervical Cancer: Analysis of Regional Control and Recurrence Patterns in the Positron Emission Tomography/Computed Tomography Era

    Energy Technology Data Exchange (ETDEWEB)

    Vargo, John A.; Kim, Hayeon; Choi, Serah [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania (United States); Sukumvanich, Paniti; Olawaiye, Alexander B.; Kelley, Joseph L.; Edwards, Robert P.; Comerci, John T. [Department of Gynecologic Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania (United States); Beriwal, Sushil, E-mail: beriwals@upmc.edu [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania (United States)

    2014-12-01

    Purpose: Positron emission tomography/computed tomography (PET/CT) is commonly used for nodal staging in locally advanced cervical cancer; however the false negative rate for para-aortic disease are 20% to 25% in PET-positive pelvic nodal disease. Unless surgically staged, pelvis-only treatment may undertreat para-aortic disease. We have treated patients with PET-positive nodes with extended field intensity modulated radiation therapy (IMRT) to address the para-aortic region prophylactically with concomitant boost to involved nodes. The purpose of this study was to assess regional control rates and recurrence patterns. Methods and Materials: Sixty-one patients with cervical cancer (stage IBI-IVA) diagnosed from 2003 to 2012 with PET-avid pelvic nodes treated with extended field IMRT (45 Gy in 25 fractions with concomitant boost to involved nodes to a median of 55 Gy in 25 fractions) with concurrent cisplatin and brachytherapy were retrospectively analyzed. The nodal location was pelvis-only in 41 patients (67%) and pelvis + para-aortic in 20 patients (33%). There were a total of 179 nodes, with a median number of positive nodes of 2 (range, 1-16 nodes) per patient and a median nodal size of 1.8 cm (range, 0.7-4.5 cm). Response was assessed by PET/CT at 12 to 16 weeks. Results: Complete clinical and imaging response at the first follow-up visit was seen in 77% of patients. At a mean follow-up time of 29 months (range, 3-116 months), 8 patients experienced recurrence. The sites of persistent/recurrent disease were as follows: cervix 10 (16.3%), regional nodes 3 (4.9%), and distant 14 (23%). The rate of para-aortic failure in patients with pelvic-only nodes was 2.5%. There were no significant differences in recurrence patterns by the number/location of nodes, largest node size, or maximum node standardized uptake value. The rate of late grade 3+ adverse events was 4%. Conclusions: Extended field IMRT was well tolerated and resulted in low regional recurrence

  7. Extended Field Intensity Modulated Radiation Therapy With Concomitant Boost for Lymph Node–Positive Cervical Cancer: Analysis of Regional Control and Recurrence Patterns in the Positron Emission Tomography/Computed Tomography Era

    International Nuclear Information System (INIS)

    Purpose: Positron emission tomography/computed tomography (PET/CT) is commonly used for nodal staging in locally advanced cervical cancer; however the false negative rate for para-aortic disease are 20% to 25% in PET-positive pelvic nodal disease. Unless surgically staged, pelvis-only treatment may undertreat para-aortic disease. We have treated patients with PET-positive nodes with extended field intensity modulated radiation therapy (IMRT) to address the para-aortic region prophylactically with concomitant boost to involved nodes. The purpose of this study was to assess regional control rates and recurrence patterns. Methods and Materials: Sixty-one patients with cervical cancer (stage IBI-IVA) diagnosed from 2003 to 2012 with PET-avid pelvic nodes treated with extended field IMRT (45 Gy in 25 fractions with concomitant boost to involved nodes to a median of 55 Gy in 25 fractions) with concurrent cisplatin and brachytherapy were retrospectively analyzed. The nodal location was pelvis-only in 41 patients (67%) and pelvis + para-aortic in 20 patients (33%). There were a total of 179 nodes, with a median number of positive nodes of 2 (range, 1-16 nodes) per patient and a median nodal size of 1.8 cm (range, 0.7-4.5 cm). Response was assessed by PET/CT at 12 to 16 weeks. Results: Complete clinical and imaging response at the first follow-up visit was seen in 77% of patients. At a mean follow-up time of 29 months (range, 3-116 months), 8 patients experienced recurrence. The sites of persistent/recurrent disease were as follows: cervix 10 (16.3%), regional nodes 3 (4.9%), and distant 14 (23%). The rate of para-aortic failure in patients with pelvic-only nodes was 2.5%. There were no significant differences in recurrence patterns by the number/location of nodes, largest node size, or maximum node standardized uptake value. The rate of late grade 3+ adverse events was 4%. Conclusions: Extended field IMRT was well tolerated and resulted in low regional recurrence

  8. Prospective study of special stage II (T 2b-3 N 0 M 0 non-small-cell lung cancer treated with hypofractionated-simultaneous integrated boost-intensity modulated radiation therapy

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2015-01-01

    Full Text Available Purpose: To analyze the effects of hypofractionated-simultaneous integrated boost-intensity modulated radiation therapy (Hypo-SIB-IMRT on medically inoperable patients with special stage II (T 2b-3 N 0 M 0 non-smallcell lung cancer (NSCLC. Materials and Methods: Twenty-eight qualified patients were included. Hypo-SIB-IMRT was delivered with internal gross tumor volume (iGTV 75Gy, clinical target volume (CTV 60Gy, and planning target volume (PTV 45Gy on weekdays in 3 weeks. Results: The 1-, 2-, and 3-year overall survivals (OSs were 93, 85, and 61%, respectively, with a median survival of 46.5 months; while progression-free survivals (PFSs were 92, 79, and 64%; and distant metastasis-free survivals (DMFSs were 92, 84, and 77%, respectively. The cancer-specific survivals (CSS were 93, 88, and 74%, and local control (LC were 92, 83, and 74%, respectively. 7.1% (2/28 of patients occurred local pain, 28.6% (8/28 were with Grade 1or 2 radiation pneumonitis (RP, and 7.1% (2/28 with Grade 1 esophagitis. Of the eight patients with RP, 17.9% (5/28 developed Grade 1 radiation pulmonary fibrosis (RPF. Conclusion: Due to the favorable long-term survivals, LC, and minimal toxicities, Hypo-SIB-IMRT presented in this prospective study may be considered an option for patients with special stage II (T 2b-3 N 0 M 0 NSCLC who were medically inoperable.

  9. A randomized phase II/III study of adverse events between sequential (SEQ) versus simultaneous integrated boost (SIB) intensity modulated radiation therapy (IMRT) in nasopharyngeal carcinoma; preliminary result on acute adverse events

    International Nuclear Information System (INIS)

    To investigate acute and late toxicities comparing sequential (SEQ-IMRT) versus simultaneous integrated boost intensity modulated radiotherapy (SIB-IMRT) in nasopharyngeal carcinoma (NPC) patients. Newly diagnosed stage I-IVB NPC patients were randomized to receive SEQ-IMRT or SIB-IMRT, with or without chemotherapy. SEQ-IMRT consisted of two sequential radiation treatment plans: 2Gy x 25 fractions to low-risk planning target volume (PTV-LR) followed by 2Gy x 10 fractions to high-risk planning target volume (PTV-HR). In contrast, SIB-IMRT consisted of only one treatment plan: 2.12Gy and 1.7Gy x 33 fractions to PTV-HR and PTV-LR, respectively. Toxicities were evaluated according to CTCAE version 4.0. Between October 2010 and November 2013, 122 eligible patients were randomized between SEQ-IMRT (54 patients) and SIB-IMRT (68 patients). With median follow-up time of 16.8 months, there was no significant difference in toxicities between the two IMRT techniques. During chemoradiation, the most common grade 3–5 acute toxicities were mucositis (15.4 % vs 13.6 %, SEQ vs SIB, p = 0.788) followed by dysphagia (9.6 % vs 9.1 %, p = 1.000) and xerostomia (9.6 % vs 7.6 %, p = 0.748). During the adjuvant chemotherapy period, 25.6 % and 32.7 % experienced grade 3 weight loss in SEQ-IMRT and SIB-IMRT (p = 0.459). One-year overall survival (OS) and progression-free survival (PFS) were 95.8 % and 95.5 % in SEQ-IMRT and 98 % and 90.2 % in SIB-IMRT, respectively (p = 0.472 for OS and 0.069 for PFS). This randomized, phase II/III trial comparing SIB-IMRT versus SEQ-IMRT in NPC showed no statistically significant difference between both IMRT techniques in terms of acute adverse events. Short-term tumor control and survival outcome were promising

  10. Intensity-modulated radiation therapy.

    Science.gov (United States)

    Goffman, Thomas E; Glatstein, Eli

    2002-07-01

    Intensity-modulated radiation therapy (IMRT) is an increasingly popular technical means of tightly focusing the radiation dose around a cancer. As with stereotactic radiotherapy, IMRT uses multiple fields and angles to converge on the target. The potential for total dose escalation and for escalation of daily fraction size to the gross cancer is exciting. The excitement, however, has greatly overshadowed a range of radiobiological and clinical concerns. PMID:12071811

  11. COSMIC: A Regimen of Intensity Modulated Radiation Therapy Plus Dose-Escalated, Raster-Scanned Carbon Ion Boost for Malignant Salivary Gland Tumors: Results of the Prospective Phase 2 Trial

    International Nuclear Information System (INIS)

    Purpose: To investigate the effect of intensity modulated radiation therapy (IMRT) and dose-escalated carbon ion (C12) therapy in adenoid cystic carcinoma (ACC) and other malignant salivary gland tumors (MSGTs) of the head and neck. Patients and Methods: COSMIC (combined treatment of malignant salivary gland tumors with intensity modulated radiation therapy and carbon ions) is a prospective phase 2 trial of 24 Gy(RBE) C12 followed by 50 Gy IMRT in patients with pathologically confirmed MSGT. The primary endpoint is mucositis Common Terminology Criteria grade 3; the secondary endpoints are locoregional control (LC), progression-free survival (PFS), overall survival (OS), and toxicity. Toxicity was scored according to the Common Terminology Criteria for Adverse Events version 3; treatment response was scored according to Response Evaluation Criteria in Solid Tumors 1.1. Results: Between July 2010 and August 2011, 54 patients were accrued, and 53 were available for evaluation. The median follow-up time was 42 months; patients with microscopically incomplete resections (R1, n=20), gross residual disease (R2, n=17), and inoperable disease (n=16) were included. Eighty-nine percent of patients had ACC, and 57% had T4 tumors. The most common primary sites were paranasal sinus (34%), submandibular gland, and palate. At the completion of radiation therapy, 26% of patients experienced grade 3 mucositis, and 20 patients reported adverse events of the ear (38%). The most common observed late effects were grade 1 xerostomia (49%), hearing impairment (25%, 2% ipsilateral hearing loss), and adverse events of the eye (20%), but no visual impairment or loss of vision. Grade 1 central nervous system necrosis occurred in 6%, and 1 grade 4 ICA hemorrhage without neurologic sequelae. The best response was 54% (complete response/partial remission). At 3 years, the LC, PFS, and OS were 81.9%, 57.9%, and 78.4%, respectively. No difference was found regarding resection status. The

  12. COSMIC: A Regimen of Intensity Modulated Radiation Therapy Plus Dose-Escalated, Raster-Scanned Carbon Ion Boost for Malignant Salivary Gland Tumors: Results of the Prospective Phase 2 Trial

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Alexandra D., E-mail: alexdjensen@gmx.de [Department of Radiation Oncology, University of Heidelberg, Heidelberg (Germany); Nikoghosyan, Anna V.; Lossner, Karen [Department of Radiation Oncology, University of Heidelberg, Heidelberg (Germany); Haberer, Thomas; Jäkel, Oliver [Heidelberg Ion Beam Therapy Centre, Heidelberg (Germany); Münter, Marc W.; Debus, Jürgen [Department of Radiation Oncology, University of Heidelberg, Heidelberg (Germany)

    2015-09-01

    Purpose: To investigate the effect of intensity modulated radiation therapy (IMRT) and dose-escalated carbon ion (C12) therapy in adenoid cystic carcinoma (ACC) and other malignant salivary gland tumors (MSGTs) of the head and neck. Patients and Methods: COSMIC (combined treatment of malignant salivary gland tumors with intensity modulated radiation therapy and carbon ions) is a prospective phase 2 trial of 24 Gy(RBE) C12 followed by 50 Gy IMRT in patients with pathologically confirmed MSGT. The primary endpoint is mucositis Common Terminology Criteria grade 3; the secondary endpoints are locoregional control (LC), progression-free survival (PFS), overall survival (OS), and toxicity. Toxicity was scored according to the Common Terminology Criteria for Adverse Events version 3; treatment response was scored according to Response Evaluation Criteria in Solid Tumors 1.1. Results: Between July 2010 and August 2011, 54 patients were accrued, and 53 were available for evaluation. The median follow-up time was 42 months; patients with microscopically incomplete resections (R1, n=20), gross residual disease (R2, n=17), and inoperable disease (n=16) were included. Eighty-nine percent of patients had ACC, and 57% had T4 tumors. The most common primary sites were paranasal sinus (34%), submandibular gland, and palate. At the completion of radiation therapy, 26% of patients experienced grade 3 mucositis, and 20 patients reported adverse events of the ear (38%). The most common observed late effects were grade 1 xerostomia (49%), hearing impairment (25%, 2% ipsilateral hearing loss), and adverse events of the eye (20%), but no visual impairment or loss of vision. Grade 1 central nervous system necrosis occurred in 6%, and 1 grade 4 ICA hemorrhage without neurologic sequelae. The best response was 54% (complete response/partial remission). At 3 years, the LC, PFS, and OS were 81.9%, 57.9%, and 78.4%, respectively. No difference was found regarding resection status. The

  13. Dose-escalation using intensity-modulated radiotherapy for prostate cancer - evaluation of quality of life with and without 18F-choline PET-CT detected simultaneous integrated boost

    International Nuclear Information System (INIS)

    In comparison to the conventional whole-prostate dose escalation, an integrated boost to the macroscopic malignant lesion might potentially improve tumor control rates without increasing toxicity. Quality of life after radiotherapy (RT) with vs. without 18F-choline PET-CT detected simultaneous integrated boost (SIB) was prospectively evaluated in this study. Whole body image acquisition in supine patient position followed 1 h after injection of 178-355MBq 18F-choline. SIB was defined by a tumor-to-background uptake value ratio > 2 (GTVPET). A dose of 76Gy was prescribed to the prostate (PTVprostate) in 2Gy fractions, with or without SIB up to 80Gy. Patients treated with (n = 46) vs. without (n = 21) SIB were surveyed prospectively before (A), at the last day of RT (B) and a median time of two (C) and 19 month (D) after RT to compare QoL changes applying a validated questionnaire (EPIC - expanded prostate cancer index composite). With a median cut-off standard uptake value (SUV) of 3, a median GTVPET of 4.0 cm3 and PTVboost (GTVPET with margins) of 17.3 cm3 was defined. No significant differences were found for patients treated with vs. without SIB regarding urinary and bowel QoL changes at times B, C and D (mean differences ≤3 points for all comparisons). Significantly decreasing acute urinary and bowel score changes (mean changes > 5 points in comparison to baseline level at time A) were found for patients with and without SIB. However, long-term urinary and bowel QoL (time D) did not differ relative to baseline levels - with mean urinary and bowel function score changes < 3 points in both groups (median changes = 0 points). Only sexual function scores decreased significantly (> 5 points) at time D. Treatment planning with 18F-choline PET-CT allows a dose escalation to a macroscopic intraprostatic lesion without significantly increasing toxicity

  14. To boost or not boost in radiotherapy

    International Nuclear Information System (INIS)

    The aim of this paper it to analyse and discuss standard definition of the 'boost' procedure in relation to clinical results and new forms of the boost designed on physical and radiobiological bases. Seventeen sets of clinical data including over 5000 cases cancer with different tumour stages and locations and treated with various forms of 'boost' method have been subtracted from literature. Effectiveness of boost is analyzed regarding its place in combined treatment, timing and subvolume involved. Radiobiological parameter of D10 and normalization method for biologically equivalent doses and dose intensity are used to simulated cold and not subvolumes (hills and dales) and its influence of effectiveness on the boost delivery. Sequential and concomitant boost using external irradiation, although commonly used, offers LTC benefit lower than expected. Brachytherapy, intraoperative irradiation and concurrent chemotherapy boost methods appear more effective. Conformal radiotherapy, with or without dose-intensity modulation, allows heterogeneous increase in dose intensity within the target volume and can be used to integrate the 'boost dose' into baseline treatment (Simultaneous Integrated Boost and SIB). Analysis of interrelationships between boost-dose; boost volume and its timing shows that a TCP benefit from boosting can be expected when a relatively large part of the target volume is involved. Increase in boost dose above 1.2-1.3 of baseline dose using 'standard' methods does not substantially further increase the achieved TCP benefit unless hypoxic cells are a problem. Any small uncertainties in treatment planning can ruin all potential beneficial effect of the boost. For example, a 50% dose deficit in a very small (e.g. 1%) volume of target can decrease TCP to zero. Therefore boost benefits should be carefully weighed against any risk of cold spots in the target volume. Pros and cons in discussion of the role of boost in radiotherapy lead to the important

  15. Fan-beam intensity modulated proton therapy

    OpenAIRE

    Hill, Patrick; Westerly, David; Mackie, Thomas

    2013-01-01

    Purpose: This paper presents a concept for a proton therapy system capable of delivering intensity modulated proton therapy using a fan beam of protons. This system would allow present and future gantry-based facilities to deliver state-of-the-art proton therapy with the greater normal tissue sparing made possible by intensity modulation techniques.

  16. Plasma optical modulators for intense lasers

    CERN Document Server

    Yu, Lu-Le; Qian, Lie-Jia; Chen, Min; Weng, Su-Ming; Sheng, Zheng-Ming; Jaroszynski, D A; Mori, W B; Zhang, Jie

    2016-01-01

    Optical modulators can be made nowadays with high modulation speed, broad bandwidth, while being compact, owing to the recent advance in material science and microfabrication technology. However, these optical modulators usually work for low intensity light beams. Here, we present an ultrafast, plasma-based optical modulator, which can directly modulate high power lasers with intensity up to 10^16 W/cm^2 level to produce an extremely broad spectrum with a fractional bandwidth over 100%, extending to the mid-infrared regime in the low-frequency side. This concept relies on two co-propagating laser beams in a sub-mm-scale underdense plasma, where a drive laser pulse first excites an electron plasma wave in its wake while a following carrier laser beam is modulated by the plasma wave. The laser and plasma parameters suitable for the modulator to work are presented. Such optical modulators may enable new applications in the high field physics.

  17. Phase II study of induction chemotherapy with TPF followed by radioimmunotherapy with Cetuximab and intensity-modulated radiotherapy (IMRT) in combination with a carbon ion boost for locally advanced tumours of the oro-, hypopharynx and larynx - TPF-C-HIT

    OpenAIRE

    Mavtratzas Athanasios; Habl Gregor; Desta Almaz; Potthoff Karin; Krauss Jürgen; Jensen Alexandra D; Windemuth-Kiesselbach Christine; Debus Jürgen; Münter Marc W

    2011-01-01

    Abstract Background Long-term locoregional control in locally advanced squamous cell carcinoma of the head and neck (SCCHN) remains challenging. While recent years have seen various approaches to improve outcome by intensification of treatment schedules through introduction of novel induction and combination chemotherapy regimen and altered fractionation regimen, patient tolerance to higher treatment intensities is limited by accompanying side-effects. Combined radioimmunotherapy with cetuxim...

  18. Plasma optical modulators for intense lasers

    Science.gov (United States)

    Yu, Lu-Le; Zhao, Yao; Qian, Lie-Jia; Chen, Min; Weng, Su-Ming; Sheng, Zheng-Ming; Jaroszynski, D. A.; Mori, W. B.; Zhang, Jie

    2016-01-01

    Optical modulators can have high modulation speed and broad bandwidth, while being compact. However, these optical modulators usually work for low-intensity light beams. Here we present an ultrafast, plasma-based optical modulator, which can directly modulate high-power lasers with intensity up to 1016 W cm−2 to produce an extremely broad spectrum with a fractional bandwidth over 100%, extending to the mid-infrared regime in the low-frequency side. This concept relies on two co-propagating laser pulses in a sub-millimetre-scale underdense plasma, where a drive laser pulse first excites an electron plasma wave in its wake while a following carrier laser pulse is modulated by the plasma wave. The laser and plasma parameters suitable for the modulator to work are based on numerical simulations. PMID:27283369

  19. Plasma optical modulators for intense lasers

    Science.gov (United States)

    Yu, Lu-Le; Zhao, Yao; Qian, Lie-Jia; Chen, Min; Weng, Su-Ming; Sheng, Zheng-Ming; Jaroszynski, D. A.; Mori, W. B.; Zhang, Jie

    2016-06-01

    Optical modulators can have high modulation speed and broad bandwidth, while being compact. However, these optical modulators usually work for low-intensity light beams. Here we present an ultrafast, plasma-based optical modulator, which can directly modulate high-power lasers with intensity up to 1016 W cm-2 to produce an extremely broad spectrum with a fractional bandwidth over 100%, extending to the mid-infrared regime in the low-frequency side. This concept relies on two co-propagating laser pulses in a sub-millimetre-scale underdense plasma, where a drive laser pulse first excites an electron plasma wave in its wake while a following carrier laser pulse is modulated by the plasma wave. The laser and plasma parameters suitable for the modulator to work are based on numerical simulations.

  20. Prone Breast Intensity Modulated Radiation Therapy: 5-Year Results

    Energy Technology Data Exchange (ETDEWEB)

    Osa, Etin-Osa O.; DeWyngaert, Keith [Department of Radiation Oncology, New York University School of Medicine, New York, New York (United States); Roses, Daniel [Department of Surgery, New York University School of Medicine, New York, New York (United States); Speyer, James [Department of Medical Oncology, New York University School of Medicine, New York, New York (United States); Guth, Amber; Axelrod, Deborah [Department of Surgery, New York University School of Medicine, New York, New York (United States); Fenton Kerimian, Maria [Department of Radiation Oncology, New York University School of Medicine, New York, New York (United States); Goldberg, Judith D. [Department of Population Health, New York University School of Medicine, New York, New York (United States); Formenti, Silvia C., E-mail: Silvia.formenti@nyumc.org [Department of Radiation Oncology, New York University School of Medicine, New York, New York (United States)

    2014-07-15

    Purpose: To report the 5-year results of a technique of prone breast radiation therapy delivered by a regimen of accelerated intensity modulated radiation therapy with a concurrent boost to the tumor bed. Methods and Materials: Between 2003 and 2006, 404 patients with stage I-II breast cancer were prospectively enrolled into 2 consecutive protocols, institutional trials 03-30 and 05-181, that used the same regimen of 40.5 Gy/15 fractions delivered to the index breast over 3 weeks, with a concomitant daily boost to the tumor bed of 0.5 Gy (total dose 48 Gy). All patients were treated after segmental mastectomy and had negative margins and nodal assessment. Patients were set up prone: only if lung or heart volumes were in the field was a supine setup attempted and chosen if found to better spare these organs. Results: Ninety-two percent of patients were treated prone, 8% supine. Seventy-two percent had stage I, 28% stage II invasive breast cancer. In-field lung volume ranged from 0 to 228.27 cm{sup 3}, mean 19.65 cm{sup 3}. In-field heart volume for left breast cancer patients ranged from 0 to 21.24 cm{sup 3}, mean 1.59 cm{sup 3}. There was no heart in the field for right breast cancer patients. At a median follow-up of 5 years, the 5-year cumulative incidence of isolated ipsilateral breast tumor recurrence was 0.82% (95% confidence interval [CI] 0.65%-1.04%). The 5-year cumulative incidence of regional recurrence was 0.53% (95% CI 0.41%-0.69%), and the 5-year overall cumulative death rate was 1.28% (95% CI 0.48%-3.38%). Eighty-two percent (95% CI 77%-85%) of patients judged their final cosmetic result as excellent/good. Conclusions: Prone accelerated intensity modulated radiation therapy with a concomitant boost results in excellent local control and optimal sparing of heart and lung, with good cosmesis. Radiation Therapy Oncology Group protocol 1005, a phase 3, multi-institutional, randomized trial is ongoing and is evaluating the equivalence of a similar dose and

  1. First results of the Los Alamos polyphase boost converter-modulator

    International Nuclear Information System (INIS)

    This paper describes the first full-scale electrical test results of the Los Alamos polyphase boost converter-modulator being developed for the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. The convertrr-modulator provides 140 kV, 1.2 mS, 60 Hz pulses to a 5 MW, 805 MHz klystron. The system, which has 1 MW average power, derives its +/- 1250 Volt DC buss link voltages from a standard 3-phase utility 13.8 kV to 2100 volt transformer. An SCR pre-regulator provides a soft-start function in addition to correction of line and load variations, from no-load to full-load. Energy storage is provided by low inductance self-clearing metallized hazy polypropylene traction capacitors. Each of the 3-phase H-bridge Insulated Gate Bipolar Transistor (IGBT) Pulse-Width Modulation (PWM) drivers are resonated with the amorphous nanocrystalline boost transformer and associated peaking circuits to provide zero-voltage-switching characteristics for the IGBT's. This design feature minimizes IGBT switching losses. By PWM of individual IGBT conduction angles, output pulse regulation with adaptive feedforward and feedback techniques is used to improve the klystron voltage pulse shape. In addition to the first operational results, this paper will discuss the relevant design techniques associated with the boost converter-modulator topology.

  2. Speckle dynamics for intensity-modulated illumination

    International Nuclear Information System (INIS)

    We analyze the dynamics of laser speckle patterns, designed for sensing with a receiver, based on spatial filtering. The speckle translation arises after free-space propagation of light scattered from nonspecular surfaces of a solid object in motion. The speckle pattern is manipulated by modulating the intensity of the coherent light, illuminating the target. The space-time normalized cross covariance of speckle patterns incident on the spatial sensor is calculated for the field distribution of three Gaussian beams having arbitrary directions and separations when incident on the target. The modulation of the intensity distribution at the target introduce a higher spatial frequency component in the speckle pattern. The theoretical analysis provides the statistical parameters for both the speckles and the higher spatial frequency component. The analysis reveals that the speckles and the higher spatial frequency component do not necessarily translate as a rigid structure. The theoretical findings are supported by measurements

  3. Fan-beam intensity modulated proton therapy

    International Nuclear Information System (INIS)

    Purpose: This paper presents a concept for a proton therapy system capable of delivering intensity modulated proton therapy using a fan beam of protons. This system would allow present and future gantry-based facilities to deliver state-of-the-art proton therapy with the greater normal tissue sparing made possible by intensity modulation techniques.Methods: A method for producing a divergent fan beam of protons using a pair of electromagnetic quadrupoles is described and particle transport through the quadrupole doublet is simulated using a commercially available software package. To manipulate the fan beam of protons, a modulation device is developed. This modulator inserts or retracts acrylic leaves of varying thickness from subsections of the fan beam. Each subsection, or beam channel, creates what effectively becomes a beam spot within the fan area. Each channel is able to provide 0–255 mm of range shift for its associated beam spot, or stop the beam and act as an intensity modulator. Results of particle transport simulations through the quadrupole system are incorporated into the MCNPX Monte Carlo transport code along with a model of the range and intensity modulation device. Several design parameters were investigated and optimized, culminating in the ability to create topotherapy treatment plans using distal-edge tracking on both phantom and patient datasets.Results: Beam transport calculations show that a pair of electromagnetic quadrupoles can be used to create a divergent fan beam of 200 MeV protons over a distance of 2.1 m. The quadrupole lengths were 30 and 48 cm, respectively, with transverse field gradients less than 20 T/m, which is within the range of water-cooled magnets for the quadrupole radii used. MCNPX simulations of topotherapy treatment plans suggest that, when using the distal edge tracking delivery method, many delivery angles are more important than insisting on narrow beam channel widths in order to obtain conformal target coverage

  4. A 1 MEGAWATT POLYPHASE BOOST CONVERTER-MODULATOR FOR KLYSTRON PULSE APPLICATION

    International Nuclear Information System (INIS)

    This paper describes electrical design criteria and first operational results a 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching 20 kHz polyphase bridge, boost converter/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three ''H-Bridge'' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. PWM (pulse width modulation) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt-peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. A review of these design parameters and the first results of the performance characteristics will be presented

  5. Quality assurance methods for intensity modulated radiotherapy

    Directory of Open Access Journals (Sweden)

    Aydın ÇAKIR

    2013-06-01

    Full Text Available Intensity modulated radiation therapy (IMRT, based on the use of non-uniform radiation beam intensity of a new step in conformal radiotherapy. Was able to get the optimal dose distributions with IMRT can improve the clinical results. In case of inadequate use of IMRT, the result may be worse than conventional treatments. Multiple sub-areas the accuracy of IMRT dose used in these fields depends on the performance of linear accelerator quality control tests. Multileaf collimator (MLC positioning accuracy, table movement, gantry and collimator indicators, with a gantry rotation speed and a lot of parameters such as rates of MLC. Linear accelerators used for IMRT in the treatment of pre-defined quality control program within the mechanical and dosimetric tests should be done periodically. In this study, linear accelerators capable of IMRT and IMRT plans for quality controls were investigated in the literature.

  6. Intensity modulated radiotherapy (IMRT) in bilateral retinoblastoma

    International Nuclear Information System (INIS)

    External beam radiotherapy (EBRT) for retinoblastoma has traditionally been done with conventional radiotherapy techniques which resulted high doses to the surrounding normal tissues. A 20 month-old girl with group D bilateral retinoblastoma underwent intensity modulated radiotherapy (IMRT) to both eyes after failing chemoreduction and focal therapies including cryotherapy and transpupillary thermotherapy. In this report, we discuss the use of IMRT as a method for reducing doses to adjacent normal tissues while delivering therapeutic doses to the tumour tissues compared with 3-dimensional conformal radiotherapy (3DCRT). At one year follow-up, the patient remained free of any obvious radiation complications. Image guided IMRT provides better dose distribution than 3DCRT in retinoblastoma eyes, delivering the therapeutic dose to the tumours and minimizing adjacent tissue damage

  7. Intensity-modulated x-ray (IMXT) versus proton (IMPT) therapy for theragnostic hypoxia-based dose painting

    Energy Technology Data Exchange (ETDEWEB)

    Flynn, Ryan T; Bowen, Stephen R; Bentzen, Soeren M; Mackie, T Rockwell; Jeraj, Robert [Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI 53703 (United States)], E-mail: flynnrt@gmail.com

    2008-08-07

    In this work the abilities of intensity-modulated x-ray therapy (IMXT) and intensity-modulated proton therapy (IMPT) to deliver boosts based on theragnostic imaging were assessed. Theragnostic imaging is the use of functional or molecular imaging data for prescribing radiation dose distributions. Distal gradient tracking, an IMPT method designed for the delivery of non-uniform dose distributions, was assessed. Dose prescriptions for a hypoxic region in a head and neck squamous cell carcinoma patient were designed to either uniformly boost the region or redistribute the dose based on positron emission tomography (PET) images of the {sup 61}Cu(II)-diacetyl-bis(N{sub 4}-methylthiosemicarbazone) ({sup 61}Cu-ATSM) hypoxia surrogate. Treatment plans for the prescriptions were created for four different delivery methods: IMXT delivered with step-and-shoot and with helical tomotherapy, and IMPT delivered with spot scanning and distal gradient tracking. IMXT and IMPT delivered comparable dose distributions within the boost region for both uniform and redistributed theragnostic boosts. Normal tissue integral dose was lower by a factor of up to 3 for IMPT relative to the IMXT. For all delivery methods, the mean dose to the nearby organs at risk changed by less than 2 Gy for redistributed versus uniform boosts. The distal gradient tracking method resulted in comparable plans to the spot scanning method while reducing the number of proton beam spots by a factor of over 3.

  8. Single-energy intensity modulated proton therapy.

    Science.gov (United States)

    Farace, Paolo; Righetto, Roberto; Cianchetti, Marco

    2015-10-01

    In this note, an intensity modulated proton therapy (IMPT) technique, based on the use of high single-energy (SE-IMPT) pencil beams, is described.The method uses only the highest system energy (226 MeV) and only lateral penumbra to produce dose gradient, as in photon therapy. In the study, after a preliminary analysis of the width of proton pencil beam penumbras at different depths, SE-IMPT was compared with conventional IMPT in a phantom containing titanium inserts and in a patient, affected by a spinal chordoma with fixation rods.It was shown that SE-IMPT has the potential to produce a sharp dose gradient and that it is not affected by the uncertainties produced by metal implants crossed by the proton beams. Moreover, in the chordoma patient, target coverage and organ at risk sparing of the SE-IMPT plan resulted comparable to that of the less reliable conventional IMPT technique. Robustness analysis confirmed that SE-IMPT was not affected by range errors, which can drastically affect the IMPT plan.When accepting a low-dose spread as in modern photon techniques, SE-IMPT could be an option for the treatment of lesions (e.g. cervical bone tumours) where steep dose gradient could improve curability, and where range uncertainty, due for example to the presence of metal implants, hampers conventional IMPT. PMID:26352616

  9. Single-energy intensity modulated proton therapy

    Science.gov (United States)

    Farace, Paolo; Righetto, Roberto; Cianchetti, Marco

    2015-09-01

    In this note, an intensity modulated proton therapy (IMPT) technique, based on the use of high single-energy (SE-IMPT) pencil beams, is described. The method uses only the highest system energy (226 MeV) and only lateral penumbra to produce dose gradient, as in photon therapy. In the study, after a preliminary analysis of the width of proton pencil beam penumbras at different depths, SE-IMPT was compared with conventional IMPT in a phantom containing titanium inserts and in a patient, affected by a spinal chordoma with fixation rods. It was shown that SE-IMPT has the potential to produce a sharp dose gradient and that it is not affected by the uncertainties produced by metal implants crossed by the proton beams. Moreover, in the chordoma patient, target coverage and organ at risk sparing of the SE-IMPT plan resulted comparable to that of the less reliable conventional IMPT technique. Robustness analysis confirmed that SE-IMPT was not affected by range errors, which can drastically affect the IMPT plan. When accepting a low-dose spread as in modern photon techniques, SE-IMPT could be an option for the treatment of lesions (e.g. cervical bone tumours) where steep dose gradient could improve curability, and where range uncertainty, due for example to the presence of metal implants, hampers conventional IMPT.

  10. Circuit Averaging for Boost Converter Involving Generation of Pseudo-Random Carrier Modulation via PSIM

    Directory of Open Access Journals (Sweden)

    Anant Kumar Verma

    2014-07-01

    Full Text Available The paper reflects the approach towards the understanding of the circuit averaging method used for the power converters. Various software simulation packages are available for the purpose to be served such as MATLAB (Simulink, LTspice, PSIM (power electronics, motor drives, and dynamic system simulation etc. A mathematical analysis is done for modeling the Boost converter (Step-Up ideally as well as practically. An implementation of the Pseudo-random carrier modulation scheme is worked on the software package PSIM. Semiconductor devices used in power electronics systems(PES increases the effects of audible switching noise, electromagnetic interference etc, which is one of the major concern while designing the power converters.

  11. Intensity modulated Australian radiation therapy (IMART)

    International Nuclear Information System (INIS)

    Full text: Forward and inverse planned intensity modulated radiotherapy (IMRT) methods will be discussed. IMRT consists of providing a number of differently weighted infield beam segments with the dose from each segment being defined by the multi leaf collimator (MLC) shape and beam weighting. Inverse planned distributions are achieved by the radiotherapy planning computer (RTPC) using an iterative optimisation method to reach a dose solution. With the pinnacle RTPC the number of infield segments to achieve an approximation to the continuous segmented solution can be chosen then the dose is forward computed using these discrete segments. Quality assurance consists of placing the same segmented fields onto a water phantom on the RTPC. Then dose profiles taken at dmax are compared with film maps taken in the same real geometry on the linear accelerator. The film is scanned using a Vidar film scanner and density to dose conversion is achieved by fitting an exponential function to normalisation films. The film dose profiles are then compared with the RTPC dose profiles. A 3% match between film and RTPC has been achieved with the dose profiles provided care is taken with the leaf delivery sequence. There are some leaf delivery non idealities which the dosimetry films show. For example the matchline effect on the Varian 120 leaf MLC has been measured as a 31% hot line which occurs if one leaf drives to where the other leaf was. This effect is mainly due to the rounded leaf ends causing penumbra asymmetry whereby the top of the penumbral profile is slightly different to the bottom. This effect can be reduced by using software offsets of the leaf positions or by simply having a small number of segments with minimal leaf overlap. Copyright (2000) Australasian College of Physical Scientists and Engineers in Medicine

  12. Intensity-Modulated Radiotherapy for Pancreatic Adenocarcinoma

    International Nuclear Information System (INIS)

    Purpose: To report the outcomes and toxicities in patients treated with intensity-modulated radiotherapy (IMRT) for pancreatic adenocarcinoma. Methods and Materials: Forty-seven patients with pancreatic adenocarcinoma were treated with IMRT between 2003 and 2008. Of these 47 patients, 29 were treated adjuvantly and 18 definitively. All received concurrent 5-fluorouracil chemotherapy. The treatment plans were optimized such that 95% of the planning target volume received the prescription dose. The median delivered dose for the adjuvant and definitive patients was 50.4 and 54.0 Gy, respectively. Results: The median age at diagnosis was 63.9 years. For adjuvant patients, the 1- and 2-year overall survival rate was 79% and 40%, respectively. The 1- and 2-year recurrence-free survival rate was 58% and 17%, respectively. The local-regional control rate at 1 and 2 years was 92% and 80%, respectively. For definitive patients, the 1-year overall survival, recurrence-free survival, and local-regional control rate was 24%, 16%, and 64%, respectively. Four patients developed Grade 3 or greater acute toxicity (9%) and four developed Grade 3 late toxicity (9%). Conclusions: Survival for patients with pancreatic cancer remains poor. A small percentage of adjuvant patients have durable disease control, and with improved therapies, this proportion will increase. Systemic therapy offers the greatest opportunity. The present results have demonstrated that IMRT is well tolerated. Compared with those who received three-dimensional conformal radiotherapy in previously reported prospective clinical trials, patients with pancreatic adenocarcinoma treated with IMRT in our series had improved acute toxicity.

  13. Planning With Intensity-Modulated Radiotherapy and Tomotherapy to Modulate Dose Across Breast to Reflect Recurrence Risk (IMPORT High Trial)

    International Nuclear Information System (INIS)

    Purpose: To establish planning solutions for a concomitant three-level radiation dose distribution to the breast using linear accelerator- or tomotherapy-based intensity-modulated radiotherapy (IMRT), for the U.K. Intensity Modulated and Partial Organ (IMPORT) High trial. Methods and Materials: Computed tomography data sets for 9 patients undergoing breast conservation surgery with implanted tumor bed gold markers were used to prepare three-level dose distributions encompassing the whole breast (36 Gy), partial breast (40 Gy), and tumor bed boost (48 or 53 Gy) treated concomitantly in 15 fractions within 3 weeks. Forward and inverse planned IMRT and tomotherapy were investigated as solutions. A standard electron field was compared with a photon field arrangement encompassing the tumor bed boost volume. The out-of-field doses were measured for all methods. Results: Dose-volume constraints of volume >90% receiving 32.4 Gy and volume >95% receiving 50.4 Gy for the whole breast and tumor bed were achieved. The constraint of volume >90% receiving 36 Gy for the partial breast was fulfilled in the inverse IMRT and tomotherapy plans and in 7 of 9 cases of a forward planned IMRT distribution. An electron boost to the tumor bed was inadequate in 8 of 9 cases. The IMRT methods delivered a greater whole body dose than the standard breast tangents. A contralateral lung volume >2.5 Gy was increased in the inverse IMRT and tomotherapy plans, although it did not exceed the constraint. Conclusion: We have demonstrated a set of widely applicable solutions that fulfilled the stringent clinical trial requirements for the delivery of a concomitant three-level dose distribution to the breast.

  14. Implementation of intensity modulation with dynamic multileaf collimation

    Energy Technology Data Exchange (ETDEWEB)

    Wong, J.W.; Yu, C.; Jaffray, D. [William Beaumont Hospital, Royal Oak, MI (United States)

    1995-12-01

    The computer-controlled multileaf collimator (MLC) marks one of the most important advances in radiation therapy. The device efficiently replaces manual blocking to shape fields and can be used to modulate beam intensity. The results of a research programme at William Beaumont Hospital, aimed at bringing dynamic intensity modulation into clinical use, are discussed.

  15. Intensity-modulated radiation therapy: emerging cancer treatment technology

    OpenAIRE

    T.S. Hong; Ritter, M. A.; Tomé, W. A.; Harari, P.M.

    2005-01-01

    The use of intensity-modulated radiation therapy (IMRT) is rapidly advancing in the field of radiation oncology. Intensity-modulated radiation therapy allows for improved dose conformality, thereby affording the potential to decrease the spectrum of normal tissue toxicities associated with IMRT. Preliminary results with IMRT are quite promising; however, the clinical data is relatively immature and overall patient numbers remain small. High-quality IMRT requires intensive physics support and ...

  16. Robust optimization of intensity modulated proton therapy

    Energy Technology Data Exchange (ETDEWEB)

    Liu Wei; Zhang Xiaodong; Li Yupeng; Mohan, Radhe [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

    2012-02-15

    Purpose: Intensity modulated proton therapy (IMPT) is highly sensitive to range uncertainties and uncertainties caused by setup variation. The conventional inverse treatment planning of IMPT optimized based on the planning target volume (PTV) is not often sufficient to ensure robustness of treatment plans. In this paper, a method that takes the uncertainties into account during plan optimization is used to mitigate the influence of uncertainties in IMPT. Methods: The authors use the so-called ''worst-case robust optimization'' to render IMPT plans robust in the face of uncertainties. For each iteration, nine different dose distributions are computed--one each for {+-} setup uncertainties along anteroposterior (A-P), lateral (R-L) and superior-inferior (S-I) directions, for {+-} range uncertainty, and the nominal dose distribution. The worst-case dose distribution is obtained by assigning the lowest dose among the nine doses to each voxel in the clinical target volume (CTV) and the highest dose to each voxel outside the CTV. Conceptually, the use of worst-case dose distribution is similar to the dose distribution achieved based on the use of PTV in traditional planning. The objective function value for a given iteration is computed using this worst-case dose distribution. The objective function used has been extended to further constrain the target dose inhomogeneity. Results: The worst-case robust optimization method is applied to a lung case, a skull base case, and a prostate case. Compared with IMPT plans optimized using conventional methods based on the PTV, our method yields plans that are considerably less sensitive to range and setup uncertainties. An interesting finding of the work presented here is that, in addition to reducing sensitivity to uncertainties, robust optimization also leads to improved optimality of treatment plans compared to the PTV-based optimization. This is reflected in reduction in plan scores and in the lower normal

  17. Dosimetric verification in intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    As part of dosimetric verification for IMRT intensity modulated radiation therapy, we examined the selection of a dosimeter in accordance with the purpose of physical measurement and the process of data analysis. Because of the high dose conformation in the target volume and minimum dose in the organs at risk (OAR) in IMRT, dosimetric verification is essential. Because the performance of dosimetric verification in a patient is not allowed, a physical phantom and dosimeter must be used. Dose verification using a physical phantom, from which the beam data optimized for a patient slated for IMRT are transferred, may cause latent error as a result of change in the depth of each beam toward an isocenter. This effect may change the dose distribution and prescription dose. The basic methods of dosimetric verification with physical measurement are point dosimetry, when the reference dose is given at a point by planning software, and volumetric dosimetry, when planning software gives the dose as a volumetric configuration. While the most accurate dosimetry is done using a calibrated ionization chamber, IMRT requires volumetric dosimetry using some kind of portal film or a polymer gel dosimeter, because of the need for dosimetric verification for an irregular dose distribution in IMRT. The importance of indirect dosimetry using these methods is to provide calibration as a dosimeter, absolute dose, and preservation of calibration. In our study, the verification of dose distribution for IMRT using portal film and RANDO phantom could be performed with an error of less than 2% in all cases. The measurement error for the central dose using a JARP-type ionization chamber and MixDP was less than 3% in all cases except for the case with the maximum error. At the moment, IMRT requires a great deal of effort in the processes of planning, dosimetric verification, and isocenter checking in every fraction to maintain high accuracy. Although the need for a large amount of effort in the

  18. Standard fractionation intensity modulated radiation therapy (IMRT) of primary and recurrent glioblastoma multiforme

    International Nuclear Information System (INIS)

    Intensity-modulated radiation therapy (IMRT) affords unparalleled capacity to deliver conformal radiation doses to tumors in the central nervous system. However, to date, there are few reported outcomes from using IMRT, either alone or as a boost technique, for standard fractionation radiotherapy for glioblastoma multiforme (GBM). Forty-two patients were treated with IMRT alone (72%) or as a boost (28%) after 3-dimensional conformal radiation therapy (3D-CRT). Thirty-three patients with primary disease and 9 patients with recurrent tumors were included. Thirty-four patients (81%) had surgery, with gross tumor resection in 13 patients (36%); 22 patients (53%) received chemo-radiotherapy. The median total radiation dose for all patients was 60 Gy with a range from 30.6 to 74 Gy. Standard fractions of 1.8 Gy/day to 2.0 Gy/day were utilized. Median survival was 8.7 months, with 37 patients (88%) deceased at last contact. Nonparametric analysis showed no survival difference in IMRT-boost vs. IMRT-only groups. While technically feasible, preliminary results suggest delivering standard radiation doses by IMRT did not improve survival outcomes in this series compared to historical controls. In light of this lack of a survival benefit and the costs associated with use of IMRT, future prospective trials are needed to evaluate non-survival endpoints such as quality of life and functional preservation. Short of such evidence, the use of IMRT for treatment of GBM needs to be carefully rationalized

  19. Radiometric modulation measuring device of intensity of optical radiation

    Directory of Open Access Journals (Sweden)

    A. P. Yanenko

    2014-04-01

    Full Text Available Introduction. The paper proposed a block diagram of radiometric measuring the intensity of optical radiation from modulation conversion parameter input . To assess the intensity of use periodically comparing the reference signal (shaded and measurement (open photodi-odes. Studies. The proposed radiometric modulation meter provides increased sensitivity and measurement accuracy by reducing the influence of dark current measurement and reference photodiodes and compensation intrinsic noise measuring channel through their periodic anti-phase comparison.

  20. Subcarrier intensity modulated free-space optical communication systems

    OpenAIRE

    Popoola, Wasiu Oyewole

    2009-01-01

    This thesis investigates and analyses the performance of terrestrial free-space optical communication (FSO) system based on the phase shift keying pre-modulated subcarrier intensity modulation (SIM). The results are theoretically and experimentally compared with the classical On-Off keying (OOK) modulated FSO system in the presence of atmospheric turbulence. The performance analysis is based on the bit error rate (BER) and outage probability metrics. Optical signal traversing the atmospheric ...

  1. Stimulus intensity modulates multisensory temporal processing.

    Science.gov (United States)

    Krueger Fister, Juliane; Stevenson, Ryan A; Nidiffer, Aaron R; Barnett, Zachary P; Wallace, Mark T

    2016-07-29

    One of the more challenging feats that multisensory systems must perform is to determine which sensory signals originate from the same external event, and thus should be integrated or "bound" into a singular perceptual object or event, and which signals should be segregated. Two important stimulus properties impacting this process are the timing and effectiveness of the paired stimuli. It has been well established that the more temporally aligned two stimuli are, the greater the degree to which they influence one another's processing. In addition, the less effective the individual unisensory stimuli are in eliciting a response, the greater the benefit when they are combined. However, the interaction between stimulus timing and stimulus effectiveness in driving multisensory-mediated behaviors has never been explored - which was the purpose of the current study. Participants were presented with either high- or low-intensity audiovisual stimuli in which stimulus onset asynchronies (SOAs) were parametrically varied, and were asked to report on the perceived synchrony/asynchrony of the paired stimuli. Our results revealed an interaction between the temporal relationship (SOA) and intensity of the stimuli. Specifically, individuals were more tolerant of larger temporal offsets (i.e., more likely to call them synchronous) when the paired stimuli were less effective. This interaction was also seen in response time (RT) distributions. Behavioral gains in RTs were seen with synchronous relative to asynchronous presentations, but this effect was more pronounced with high-intensity stimuli. These data suggest that stimulus effectiveness plays an underappreciated role in the perception of the timing of multisensory events, and reinforces the interdependency of the principles of multisensory integration in determining behavior and shaping perception. PMID:26920937

  2. Depth and Intensity Gabor Features Based 3D Face Recognition Using Symbolic LDA and AdaBoost

    Directory of Open Access Journals (Sweden)

    P. S. Hiremath

    2013-11-01

    Full Text Available In this paper, the objective is to investigate what contributions depth and intensity information make to the solution of face recognition problem when expression and pose variations are taken into account, and a novel system is proposed for combining depth and intensity information in order to improve face recognition performance. In the proposed approach, local features based on Gabor wavelets are extracted from depth and intensity images, which are obtained from 3D data after fine alignment. Then a novel hierarchical selecting scheme embedded in symbolic linear discriminant analysis (Symbolic LDA with AdaBoost learning is proposed to select the most effective and robust features and to construct a strong classifier. Experiments are performed on the three datasets, namely, Texas 3D face database, Bhosphorus 3D face database and CASIA 3D face database, which contain face images with complex variations, including expressions, poses and longtime lapses between two scans. The experimental results demonstrate the enhanced effectiveness in the performance of the proposed method. Since most of the design processes are performed automatically, the proposed approach leads to a potential prototype design of an automatic face recognition system based on the combination of the depth and intensity information in face images.

  3. Quasi-periodic modulation of equatorial noise intensity

    Science.gov (United States)

    Nemec, Frantisek; Santolik, Ondrej; Hrbackova, Zuzana; Pickett, Jolene S.; Cornilleau-Wehrlin, Nicole

    2015-04-01

    Equatorial noise (EN) emissions are electromagnetic waves at frequencies between the proton cyclotron frequency and the lower hybrid frequency observed routinely in the equatorial region of the inner magnetosphere. They propagate in the extraordinary mode nearly perpendicular to the ambient magnetic field. Although their harmonic structure, which is characteristic of the proton cyclotron frequency in the source region has been known for a couple of decades, they were generally believed to be continuous in time. The analysis of more than 2000 EN events observed by the STAFF-SA and WBD instruments on board the Cluster spacecraft reveals that this is not always the case, with about 5% of events exhibiting a clear quasi-periodic (QP) modulation of the wave intensity. We perform a systematic analysis of these events, and we discuss possible mechanisms of the QP intensity modulation. It is shown that the events occur usually in the noon-to-dawn magnetic local time sector, and their occurrence seems to be related to the periods of increased geomagnetic activity. The modulation period of these events is on the order of minutes. Compressional ULF magnetic field pulsations with periods about double the modulation periods of EN were identified in about half of the events. These ULF pulsations might modulate the EN wave intensity, similarly as they modulate the intensity of formerly reported VLF whistler-mode QP events.

  4. Modulational instability of intense laser beam in magnetized plasma

    International Nuclear Information System (INIS)

    The nonlinear dispersion relation is derived for an intense left-hand elliptically polarized laser beam propagating through magnetized plasma by means of the Lorentz transformation. In terms of the Karpman method, the nonlinear governing equation for the envelope of the laser field is obtained. The modulational instability of the intense left-hand elliptically polarized laser beam in magnetized plasma is analyzed and the temporal growth rate of modulational instability is found. The analysis shows that the maximum growth rate of self-modulation instability is obviously smaller for magnetized plasma compared to the unmagnetized case. It is also shown that the temporal growth rate of modulational instability is increased significantly near the critical surface in a laser-plasma. (authors)

  5. Simulation Of Intensity Modulate Radiation Therapy By Using PENELOPE

    International Nuclear Information System (INIS)

    In this paper we present about the simulation of intensity modulate radiation therapy (IMRT) with PENELOPE. The simulation of IMRT in here involves two problems, the first is the modulation with tomotherapy and the second is the modulation with the movement of the multileaf collimator. Obtained results is the distribution of absorbed dose on the target volume and the organs at risk (OARs). The results show that IMRT could give a desired distribution of dose, which is enough for the target to kill the cancer cells and prevent the over dose to OARs. This paper also shows how to use PENELOPE for studies of the distribution of absorbed dose in radiotherapy. (author)

  6. Light induced modulation instability of surfaces under intense illumination

    KAUST Repository

    Burlakov, V. M.

    2013-12-17

    We show that a flat surface of a polymer in rubber state illuminated with intense electromagnetic radiation is unstable with respect to periodic modulation. Initial periodic perturbation is amplified due to periodic thermal expansion of the material heated by radiation. Periodic heating is due to focusing-defocusing effects caused by the initial surface modulation. The surface modulation has a period longer than the excitation wavelength and does not require coherent light source. Therefore, it is not related to the well-known laser induced periodic structures on polymer surfaces but may contribute to their formation and to other phenomena of light-matter interaction.

  7. Topological Design and Modulation Strategy for Buck-Boost Three-Level Inverters

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Gao, F.; Blaabjerg, Frede;

    2007-01-01

    To date, designed topologies for dc-ac inversion with both voltage-buck and boost capabilities are mainly focused on two-level circuitries with extensions to three-level possibilities left nearly unexplored. Contributing to this area of research, this paper presents the design of a number of viab...

  8. Pulse width modulated buck-boost five-level current source inverters

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Gao, F.; Loh, P.C.;

    2008-01-01

    This paper presents new five-level current source inverters (CSIs) with voltage/current buck-boost capability. Being different from the existing multilevel CSI, the proposed CSIs were first designed to regulate the flowing path of dc input current by controlling two additional active switches, re...

  9. Standard fractionation intensity modulated radiation therapy (IMRT of primary and recurrent glioblastoma multiforme

    Directory of Open Access Journals (Sweden)

    Fuller Clifton D

    2007-07-01

    Full Text Available Abstract Background Intensity-modulated radiation therapy (IMRT affords unparalleled capacity to deliver conformal radiation doses to tumors in the central nervous system. However, to date, there are few reported outcomes from using IMRT, either alone or as a boost technique, for standard fractionation radiotherapy for glioblastoma multiforme (GBM. Methods Forty-two patients were treated with IMRT alone (72% or as a boost (28% after 3-dimensional conformal radiation therapy (3D-CRT. Thirty-three patients with primary disease and 9 patients with recurrent tumors were included. Thirty-four patients (81% had surgery, with gross tumor resection in 13 patients (36%; 22 patients (53% received chemo-radiotherapy. The median total radiation dose for all patients was 60 Gy with a range from 30.6 to 74 Gy. Standard fractions of 1.8 Gy/day to 2.0 Gy/day were utilized. Results Median survival was 8.7 months, with 37 patients (88% deceased at last contact. Nonparametric analysis showed no survival difference in IMRT-boost vs. IMRT-only groups. Conclusion While technically feasible, preliminary results suggest delivering standard radiation doses by IMRT did not improve survival outcomes in this series compared to historical controls. In light of this lack of a survival benefit and the costs associated with use of IMRT, future prospective trials are needed to evaluate non-survival endpoints such as quality of life and functional preservation. Short of such evidence, the use of IMRT for treatment of GBM needs to be carefully rationalized.

  10. A low-cost vector processor boosting compute-intensive image processing operations

    Science.gov (United States)

    Adorf, Hans-Martin

    1992-01-01

    Low-cost vector processing (VP) is within reach of everyone seriously engaged in scientific computing. The advent of affordable add-on VP-boards for standard workstations complemented by mathematical/statistical libraries is beginning to impact compute-intensive tasks such as image processing. A case in point in the restoration of distorted images from the Hubble Space Telescope. A low-cost implementation is presented of the standard Tarasko-Richardson-Lucy restoration algorithm on an Intel i860-based VP-board which is seamlessly interfaced to a commercial, interactive image processing system. First experience is reported (including some benchmarks for standalone FFT's) and some conclusions are drawn.

  11. Clinical results of intensity modulated radiotherapy for breast cancer after breast-conserving surgery

    International Nuclear Information System (INIS)

    Objective: To analyze the efficacy and cosmetic results of intensity modulate radiation therapy (IMRT) for breast cancer after breast-conserving surgery. Methods: From 2003 to 2006, 117 patients with breast cancer, after breast-conserving surgery followed by 4 - 6 cycles of chemotherapy, received intensity modulated radiotherapy (IMRT) or three-dimensional conformal radiotherapy (3DCRT). The radiation dose was 50 Gy in 25 fractions to the whole breast and 10 Gy boost to the tumor bed. Patients with positive hormone receptors then received endocrine treatment. Results: The follow-up rate was 94.0% until September 2009. 114 and 91 patients were followed up to 3 and 5 years, respectively. The 3-and 5-year overall survival rates were 99.1% and 96%. The 5-year disease free survival and local recurrence rates were 88% and 3.6%. Cosmetic results were satisfied. Severe radiation toxicities, such as radiation pneumonitis, pulmonary fibrosis and heart injury were not found. Conclusions: Patients treated with IMRT after breast-conserving surgery have a satisfied prognosis as well as cosmetic results. (authors)

  12. Energy and intensity modulated radiation therapy with electrons

    OpenAIRE

    Olofsson, Lennart

    2005-01-01

    In recent years intensity modulated radiation therapy with photons (xIMRT) has gained attention due to its ability to reduce the dose in the tissues close to the tumour volume. However, this technique also results in a large low dose volume. Electron IMRT (eIMRT) has the potential to reduce the integral dose to the patient due to the dose fall off in the electron depth dose curves. This dose fall off makes it possible to modulate the dose distribution in the direction of the beam by selecting...

  13. Intensity Position Modulation for Free-Space Laser Communication System

    Directory of Open Access Journals (Sweden)

    F. Faghihi

    2005-01-01

    Full Text Available In this study a novel analog modulation-demodulation technique for free-space laser communication system called Intensity Position Modulation (IPM is carried out. According to TEM00 mode of a laser beam and by linear fitting on the Gaussian function as an approximation, the variation of the linear part on the reverse biased pn photodiode produced various currents. Our simulated results show fine response bandwidth and fidelity of the analog communication system, is made upon the present method, is satisfactory. According to the present method, we are able to transmit the audio signals up to 1 Km.

  14. Development of modulated electron beam for intensity modulated radiation therapy (IMRT) on a photocathode electron gun

    International Nuclear Information System (INIS)

    Radiation therapy of cancer is developing to un-uniform irradiation, for concentrating dose to a cancer tumor and reducing dose to normal tissue. As a step toward the Intensity modulated radiation therapy, we examined dynamic optical modulation of electron beam produced by a photocathode electron gun. Images on photo-masks were transferred onto a photocathode by relay imaging. Electron beam could be controlled by a remote mirror. Modulated electron beam maintained its shape on acceleration, had a fine spatial resolution, and could be moved dynamically by optical methods. As a second step, optical modulation of electron beam and dynamic control succeeded by a digital micro mirror device (DMD). (author)

  15. Ultrasound-modulated optical tomography with intense acoustic bursts

    Science.gov (United States)

    Zemp, Roger J.; Kim, Chulhong; Wang, Lihong V.

    2007-04-01

    Ultrasound-modulated optical tomography (UOT) detects ultrasonically modulated light to spatially localize multiply scattered photons in turbid media with the ultimate goal of imaging the optical properties in living subjects. A principal challenge of the technique is weak modulated signal strength. We discuss ways to push the limits of signal enhancement with intense acoustic bursts while conforming to optical and ultrasonic safety standards. A CCD-based speckle-contrast detection scheme is used to detect acoustically modulated light by measuring changes in speckle statistics between ultrasound-on and ultrasound-off states. The CCD image capture is synchronized with the ultrasound burst pulse sequence. Transient acoustic radiation force, a consequence of bursts, is seen to produce slight signal enhancement over pure ultrasonic-modulation mechanisms for bursts and CCD exposure times of the order of milliseconds. However, acoustic radiation-force-induced shear waves are launched away from the acoustic sample volume, which degrade UOT spatial resolution. By time gating the CCD camera to capture modulated light before radiation force has an opportunity to accumulate significant tissue displacement, we reduce the effects of shear-wave image degradation, while enabling very high signal-to-noise ratios. Additionally, we maintain high-resolution images representative of optical and not mechanical contrast. Signal-to-noise levels are sufficiently high so as to enable acquisition of 2D images of phantoms with one acoustic burst per pixel.

  16. Dosimetric Uncertainties in Verification of Intensity Modulated Photon Beams

    International Nuclear Information System (INIS)

    The doctoral thesis presents method for the calculation of the compensators' shape to modulate linear accelerators' beams. Characteristic of the method is more strict calculation of the scattered radiation in beams with an inhomogeneous cross-section than it was before. Method could be applied in various clinical situations. It's dosimetric verification was made in phantoms, measuring dose distributions using ionization chambers as well as radiographic film. Therefore, ionization chambers were used for the evaluation of modulator shape and film was used for the evaluation of two-dimensional dose distributions. It is well known that dosimetry of the intensity modulated photon beams is rather complicated regarding inhomogeneity of the dose distribution. The main reason for that is the beam modulator which changes spectral distribution of the beam. Possibility of use different types of detectors for the measurements of dose distributions in modulated photon beams and their accuracy were examined. Small volume ionization chambers, different diodes and amorphus silicon detector and radigraphic film were used. Measured dose distributions were compared between each other as well as with distributions simulated using Monte Carlo particle transport algorithm. In this way the most accurate method for the verification of modulate photon beams is suggested. (author)

  17. A simple intensity modulation based fiber-optic accelerometer

    Science.gov (United States)

    Guozhen, Yao; Yongqian, Li; Zhi, Yang

    2016-05-01

    A fiber-optic accelerometer with simple structure and high performance based on intensity modulation is proposed. Using only a length of single mode fiber compressed by a cantilever, the intensity of reflected light is modulated by the vibration acceleration applied to it. The effects of the fiber location, the dimension parameters of the cantilever on frequency response and sensitivity are investigated. The experimental results demonstrate that the accelerometer has a flat frequency response over a 4700 Hz bandwidth and a sensitivity of 21.24 mV/g with a cantilever dimension of 30 × 8 × 1.6 mm3 and a distance of 5 mm between the fiber location and the suspended cantilever end; the coefficient of determination is better than 0.999. In addition, the effect of temperature and the stability of the sensing system are investigated.

  18. Conformal radiotherapy by intensity modulation of pediatrics tumors

    International Nuclear Information System (INIS)

    The objective of this study is to take stock on the validated and potential indications of the conformal radiotherapy with intensity modulation ( intensity modulated radiotherapy I.M.R.T.) in pediatrics and to propose recommendations for its use as well as the adapted dose constraints. About 40 to 50% of children treated for a cancer are irradiated. The I.M.R.T., by linear accelerator or helical tomo-therapy has for aim to give a homogenous dose to the target volume and to save organs at risk. Its use in pediatrics seems particularly interesting because of the complexity of target volumes and the closeness of organs at risk. In compensation for these positive elements, the importance of low doses irradiation given in big volumes makes fear event consequences on growth and an increased incidence of secondary cancers in children suffering from tumors with high cure rates and long life expectancy. (N.C.)

  19. Volumetric-modulated arc radiotherapy for pancreatic malignancies: Dosimetric comparison with sliding-window intensity-modulated radiotherapy and 3-dimensional conformal radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Nabavizadeh, Nima, E-mail: nabaviza@ohsu.edu; Simeonova, Anna O.; Waller, Joseph G.; Romer, Jeanna L.; Monaco, Debra L.; Elliott, David A.; Tanyi, James A.; Fuss, Martin; Thomas, Charles R.; Holland, John M.

    2014-10-01

    Volumetric-modulated arc radiotherapy (VMAT) is an iteration of intensity-modulated radiotherapy (IMRT), both of which deliver highly conformal dose distributions. Studies have shown the superiority of VMAT and IMRT in comparison with 3-dimensional conformal radiotherapy (3D-CRT) in planning target volume (PTV) coverage and organs-at-risk (OARs) sparing. This is the first study examining the benefits of VMAT in pancreatic cancer for doses more than 55.8 Gy. A planning study comparing 3D-CRT, IMRT, and VMAT was performed in 20 patients with pancreatic cancer. Treatments were planned for a 25-fraction delivery of 45 Gy to a large field followed by a reduced-volume 8-fraction external beam boost to 59.4 Gy in total. OARs and PTV doses, conformality index (CI) deviations from 1.0, monitor units (MUs) delivered, and isodose volumes were compared. IMRT and VMAT CI deviations from 1.0 for the large-field and the boost plans were equivalent (large field: 0.032 and 0.046, respectively; boost: 0.042 and 0.037, respectively; p > 0.05 for all comparisons). Both IMRT and VMAT CI deviations from 1.0 were statistically superior to 3D-CRT (large field: 0.217, boost: 0.177; p < 0.05 for all comparisons). VMAT showed reduction of the mean dose to the boost PTV (VMAT: 61.4 Gy, IMRT: 62.4 Gy, and 3D-CRT: 62.3 Gy; p < 0.05). The mean number of MUs per fraction was significantly lower for VMAT for both the large-field and the boost plans. VMAT delivery time was less than 3 minutes compared with 8 minutes for IMRT. Although no statistically significant dose reduction to the OARs was identified when comparing VMAT with IMRT, VMAT showed a reduction in the volumes of the 100% isodose line for the large-field plans. Dose escalation to 59.4 Gy in pancreatic cancer is dosimetrically feasible with shorter treatment times, fewer MUs delivered, and comparable CIs for VMAT when compared with IMRT.

  20. Intensity modulated radiation therapy (IMRT) for better dose targeting

    International Nuclear Information System (INIS)

    Full text: Intensity modulated radiation therapy generally implies the use of inverse planning using preselected organ dose constraints and dose volume histogram analysis. Then modulated beams are created by multi leaf collimator (MLC) sequences. This new method of modulating each beam produces fine resolution dose maps around the target volume. New and exciting tumour visualisation techniques using PET and MRS imaging may ensure that the new technology in dose delivery is matched by improved biological aided targeting images which better specifying the tumour volume. Implementing IMRT into the clinic is a complex and time consuming task however some examples of clinical sites which lend themselves to IMRT over conventional radiotherapy will be shown. One vendors approach (the pinnacle radiotherapy planning computer) is described. It maintains forward computation of the final dose map to ensure integrity of the inverse planning process. Planning dose tool calculations are compared with film dosimetry results. These comparisons ensure accurate doses are delivered to the patient

  1. Intensity Modulated Proton Beam Radiation for Brachytherapy in Patients With Cervical Carcinoma

    International Nuclear Information System (INIS)

    Purpose: To evaluate intensity modulated proton therapy (IMPT) in patients with cervical cancer in terms of coverage, conformity, and dose–volume histogram (DVH) parameters correlated with recommendations from magnetic resonance imaging (MRI)-guided brachytherapy. Methods and Materials: Eleven patients with histologically proven cervical cancer underwent primary chemoradiation for the pelvic lymph nodes, the uterus, the cervix, and the parametric region, with a symmetric margin of 1 cm. The prescription was for 50.4 Gy, with 1.8 Gy per fraction. The prescribed dose to the parametria was 2.12 Gy up to 59.36 Gy in 28 fractions as a simultaneous boost. For several reasons, the patients were unable to undergo brachytherapy. As an alternative, IMPT was planned with 5 fractions of 6 Gy to the cervix, including the macroscopic tumor with an MRI-guided target definition, with an isotropic margin of 5 mm for planning target volume (PTV) definition. Groupe-Europeen de Curietherapie and European society for Radiotherapy and Oncology (GEC-ESTRO) criteria were used for DVH evaluation. Reference comparison plans were optimized for volumetric modulated rapid arc (VMAT) therapy with the RapidArc (RA). Results: The dose to the high-risk volume was calculated with α/β = 10 with 89.6 Gy. For IMPT, the clinical target volume showed a mean dose of 38.2 ± 5.0 Gy (35.0 ±1.8 Gy for RA). The D98% was 31.9 ± 2.6 Gy (RA: 30.8 ± 1.0 Gy). With regard to the organs at risk, the 2Gy Equivalent Dose (EQD2) (α/β = 3) to 2 cm3 of the rectal wall, sigmoid wall, and bladder wall was 62.2 ± 6.4 Gy, 57.8 ± 6.1 Gy, and 80.6 ± 8.7 Gy (for RA: 75.3 ± 6.1 Gy, 66.9 ± 6.9 Gy, and 89.0 ± 7.2 Gy, respectively). For the IMPT boost plans in combination with external beam radiation therapy, all DVH parameters correlated with <5% risk for grades 2 to 4 late gastrointestinal and genitourinary toxicity. Conclusion: In patients who are not eligible for brachytherapy, IMPT as a boost technique

  2. Intensity Modulated Proton Beam Radiation for Brachytherapy in Patients With Cervical Carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Clivio, Alessandro [Oncology Institute of Southern Switzerland, Bellinzona (Switzerland); Kluge, Anne [Department of Radiation Oncology, Charité University Hospital, Berlin (Germany); Cozzi, Luca, E-mail: lucozzi@iosi.ch [Oncology Institute of Southern Switzerland, Bellinzona (Switzerland); Köhler, Christhardt [Department of Gynecology, Charité University Hospital, Berlin (Germany); Neumann, Oliver [Department of Radiation Oncology, Charité University Hospital, Berlin (Germany); Vanetti, Eugenio [Oncology Institute of Southern Switzerland, Bellinzona (Switzerland); Wlodarczyk, Waldemar; Marnitz, Simone [Department of Radiation Oncology, Charité University Hospital, Berlin (Germany)

    2013-12-01

    Purpose: To evaluate intensity modulated proton therapy (IMPT) in patients with cervical cancer in terms of coverage, conformity, and dose–volume histogram (DVH) parameters correlated with recommendations from magnetic resonance imaging (MRI)-guided brachytherapy. Methods and Materials: Eleven patients with histologically proven cervical cancer underwent primary chemoradiation for the pelvic lymph nodes, the uterus, the cervix, and the parametric region, with a symmetric margin of 1 cm. The prescription was for 50.4 Gy, with 1.8 Gy per fraction. The prescribed dose to the parametria was 2.12 Gy up to 59.36 Gy in 28 fractions as a simultaneous boost. For several reasons, the patients were unable to undergo brachytherapy. As an alternative, IMPT was planned with 5 fractions of 6 Gy to the cervix, including the macroscopic tumor with an MRI-guided target definition, with an isotropic margin of 5 mm for planning target volume (PTV) definition. Groupe-Europeen de Curietherapie and European society for Radiotherapy and Oncology (GEC-ESTRO) criteria were used for DVH evaluation. Reference comparison plans were optimized for volumetric modulated rapid arc (VMAT) therapy with the RapidArc (RA). Results: The dose to the high-risk volume was calculated with α/β = 10 with 89.6 Gy. For IMPT, the clinical target volume showed a mean dose of 38.2 ± 5.0 Gy (35.0 ±1.8 Gy for RA). The D{sub 98%} was 31.9 ± 2.6 Gy (RA: 30.8 ± 1.0 Gy). With regard to the organs at risk, the 2Gy Equivalent Dose (EQD2) (α/β = 3) to 2 cm{sup 3} of the rectal wall, sigmoid wall, and bladder wall was 62.2 ± 6.4 Gy, 57.8 ± 6.1 Gy, and 80.6 ± 8.7 Gy (for RA: 75.3 ± 6.1 Gy, 66.9 ± 6.9 Gy, and 89.0 ± 7.2 Gy, respectively). For the IMPT boost plans in combination with external beam radiation therapy, all DVH parameters correlated with <5% risk for grades 2 to 4 late gastrointestinal and genitourinary toxicity. Conclusion: In patients who are not eligible for brachytherapy, IMPT as a boost

  3. Intensity modulated radiotherapy versus volumetric modulated arc therapy in breast cancer: A comparative dosimetric analysis

    OpenAIRE

    KR Muralidhar; Bhudevi Soubhagya; Shabbir Ahmed

    2015-01-01

    Purpose: Intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) has the capacity to optimize the dose distribution. We analyzed the dosimetric differences of plans in treatment planning system (TPS) between VMAT and IMRT in treating breast cancer. Methods: Fourteen patients were simulated, planned, and treated with VMAT using single, double or partial arcs. IMRT treatments were generated using 4 to 5 tangential IMRT fields for the same patients. All treatment plan...

  4. Pump-to-Signal Intensity Modulation Transfer in Saturated- Gain Fiber Optical Parametric Amplifiers

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke; Rottwitt, Karsten;

    2011-01-01

    The pump-to-signal intensity modulation transfer in saturated degenerate FOPAs is numerically investigated over the whole gain bandwidth. The intensity modulation transfer decreases and the OSNR improves when the amplifier operates in the saturation regime....

  5. Whole pelvic intensity-modulated radiotherapy for high-risk prostate cancer: a preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Ji Hyeon; Kim, Yeon Joo; Kim, Young Seok [Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); and others

    2013-12-15

    To assess the clinical efficacy and toxicity of whole pelvic intensity-modulated radiotherapy (WP-IMRT) for high-risk prostate cancer. Patients with high-risk prostate cancer treated between 2008 and 2013 were reviewed. The study included patients who had undergone WP-IMRT with image guidance using electronic portal imaging devices and/or cone-beam computed tomography. The endorectal balloon was used in 93% of patients. Patients received either 46 Gy to the whole pelvis plus a boost of up to 76 Gy to the prostate in 2 Gy daily fractions, or 44 Gy to the whole pelvis plus a boost of up to 72.6 Gy to the prostate in 2.2 Gy fractions. The study cohort included 70 patients, of whom 55 (78%) had a Gleason score of 8 to 10 and 50 (71%) had a prostate-specific antigen level > 20 ng/mL. The androgen deprivation therapy was combined in 62 patients. The biochemical failure-free survival rate was 86.7% at 2 years. Acute any grade gastrointestinal (GI) and genitourinary (GU) toxicity rates were 47% and 73%, respectively. The actuarial rate of late grade 2 or worse toxicity at 2 years was 12.9% for GI, and 5.7% for GU with no late grade 4 toxicity. WP-IMRT was well tolerated with no severe acute or late toxicities, resulting in at least similar biochemical control to that of the historic control group with a small field. The long-term efficacy and toxicity will be assessed in the future, and a prospective randomized trial is needed to verify these findings.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-06-01

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

  7. Promising results with image guided intensity modulated radiotherapy for muscle invasive bladder cancer

    International Nuclear Information System (INIS)

    To describe the feasibility of image guided intensity modulated radiotherapy (IG-IMRT) using daily soft tissue matching in the treatment of bladder cancer. Twenty-eight patients with muscle-invasive carcinoma of the bladder were recruited to a protocol of definitive radiation using IMRT with accelerated hypofractionation with simultaneous integrated boost (SIB). Isotropic margins of .5 and 1 cm were used to generate the high risk and intermediate risk planning target volumes respectively. Cone beam CT (CBCT) was acquired daily and a soft tissue match was performed. Cystoscopy was scheduled 6 weeks post treatment. The median age was 83 years (range 58-92). Twenty patients had stage II or III disease, and eight were stage IV. Gross disease received 66 Gy in 30 fractions in 11 patients (ten with concurrent chemotherapy) or 55 Gy in 20 fractions for those of poorer performance status or with palliative intent. All patients completed radiation treatment as planned. Three patients ceased chemotherapy early due to toxicity. Six patients (21 %) had acute Grade ≥ 2 genitourinary (GU) toxicity and six (21 %) had acute Grade ≥ 2 gastrointestinal (GI) toxicity. Five patients (18 %) developed Grade ≥2 late GU toxicity and no ≥2 late GI toxicity was observed. Nineteen patients underwent cystoscopy following radiation, with complete response (CR) in 16 cases (86 %), including all patients treated with chemoradiotherapy. Eight patients relapsed, four of which were local relapses. Of the patients with local recurrence, one underwent salvage cystectomy. For patients treated with definitive intent, freedom from locoregional recurrence (FFLR) and overall survival (OS) was 90 %/100 % for chemoradiotherapy versus 86 %/69 % for radiotherapy alone. IG- IMRT using daily soft tissue matching is a feasible in the treatment of bladder cancer, enabling the delivery of accelerated synchronous integrated boost with good early local control outcomes and low toxicity

  8. Dose profile analysis of small fields in intensity modulated radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Medel B, E. [IMSS, Centro Medico Nacional Manuel Avila Camacho, Calle 2 Nte. 2004, Barrio de San Francisco, 72090 Puebla, Pue. (Mexico); Tejeda M, G.; Romero S, K., E-mail: romsakaren@gmail.com [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Fisico Matematicas, Av. San Claudio y 18 Sur, Ciudad Universitaria, 72570 Puebla, Pue.(Mexico)

    2015-10-15

    Full text: Small field dosimetry is getting a very important worldwide task nowadays. The use of fields of few centimeters is more common with the introduction of sophisticated techniques of radiation therapy, as Intensity Modulated Radiotherapy (IMRT). In our country the implementation of such techniques is just getting started and whit it the need of baseline data acquisition. The dosimetry under small field conditions represents a challenge for the physicists community. In this work, a dose profile analysis was done, using various types of dosimeters for further comparisons. This analysis includes the study of quality parameters as flatness, symmetry, penumbra, and other in-axis measurements. (Author)

  9. Dose profile analysis of small fields in intensity modulated radiotherapy

    International Nuclear Information System (INIS)

    Full text: Small field dosimetry is getting a very important worldwide task nowadays. The use of fields of few centimeters is more common with the introduction of sophisticated techniques of radiation therapy, as Intensity Modulated Radiotherapy (IMRT). In our country the implementation of such techniques is just getting started and whit it the need of baseline data acquisition. The dosimetry under small field conditions represents a challenge for the physicists community. In this work, a dose profile analysis was done, using various types of dosimeters for further comparisons. This analysis includes the study of quality parameters as flatness, symmetry, penumbra, and other in-axis measurements. (Author)

  10. Smartphone-based portable intensity modulated force sensor

    Science.gov (United States)

    Negri, Lucas H.; Schiefer, Elberth M.; Paterno, Aleksander S.; Muller, Marcia; Fabris, José L.

    2015-09-01

    This work proposes a low-cost force sensor, based on intensity modulation in an optical fibre. The transducer element is composed of a knot in a single mode fibre embedded to a silicone adhesive cuboid, and can be easily fabricated. A simple sensing scheme is devised by using a visible light source and a CCD camera of a smartphone, allowing implementation costs to be reduced. Experimental results have shown that the sensor presents a linear response and a standard uncertainty of 1:07N within the dynamical range from 0 to 30 N.

  11. Intensity modulated radiotherapy (IMRT) with concurrent chemotherapy as definitive treatment of locally advanced esophageal cancer

    International Nuclear Information System (INIS)

    To report our experience with increased dose intensity-modulated radiation and concurrent systemic chemotherapy as definitive treatment of locally advanced esophageal cancer. We analyzed 27 consecutive patients with histologically proven esophageal cancer, who were treated with increased-dose IMRT as part of their definitive therapy. The majority of patients had T3/4 and/or N1 disease (93%). Squamous cell carcinoma was the dominating histology (81%). IMRT was delivered in step-and-shoot technique in all patients using an integrated boost concept. The boost volume was covered with total doses of 56-60 Gy (single dose 2-2.14 Gy), while regional nodal regions received 50.4 Gy (single dose 1.8 Gy) in 28 fractions. Concurrent systemic therapy was scheduled in all patients and administered in 26 (96%). 17 patients received additional adjuvant systemic therapy. Loco-regional control, progression-free and overall survival as well as acute and late toxicities were retrospectively analyzed. In addition, quality of life was prospectively assessed according to the EORTC QLQs (QLQ-OG25, QLQ-H&N35 and QLQ-C30). Radiotherapy was completed as planned in all but one patient (96%), and 21 patients received more than 80% of the planned concurrent systemic therapy. We observed ten locoregional failures, transferring into actuarial 1-, 2- and 3-year-locoregional control rates of 77%, 65% and 48%. Seven patients developed distant metastases, mainly to the lung (71%). The actuarial 1-, 2- and 3-year-disease free survival rates were 58%, 48% and 36%, and overall survival rates were 82%, 61% and 56%. The concept was well tolerated, both in the clinical objective examination and also according to the subjective answers to the QLQ questionnaire. 14 patients (52%) suffered from at least one acute CTC grade 3/4 toxicity, mostly hematological side effects or dysphagia. Severe late toxicities were reported in 6 patients (22%), mostly esophageal strictures and ulcerations. Severe side effects to

  12. Intensity-Modulated Radiotherapy for Head-and-Neck Cancer in the Community Setting

    International Nuclear Information System (INIS)

    Purpose: To review outcomes with intensity-modulated radiation therapy (IMRT) in the community setting for the treatment of nasopharyngeal and oropharyngeal cancer. Methods and Materials: Between April 2003 and April 2007, 69 patients with histologically confirmed cancer of the nasopharynx and oropharynx underwent IMRT in our practice. The primary sites included nasopharynx (11), base of tongue (18), and tonsil (40). The disease stage distribution was as follows: 2 Stage I, 11 Stage II, 16 Stage III, and 40 Stage IV. All were treated with a simultaneous integrated boost IMRT technique. The median prescribed doses were 70 Gy to the planning target volume, 59.4 Gy to the high-risk subclinical volume, and 54 Gy to the low-risk subclinical volume. Forty-five patients (65%) received concurrent chemotherapy. Toxicity was graded according to the Radiation Therapy Oncology Group toxicity criteria. Progression-free and overall survival rates were estimated with the Kaplan-Meier product-limit method. Results: Median duration of follow-up was 18 months. The estimated 2-year local control, regional control, distant control, and overall survival rates were 98%, 100%, 98%, and 90%, respectively. The most common acute toxicities were dermatitis (32 Grade 1, 32 Grade 2, 5 Grade 3), mucositis (8 Grade 1, 33 Grade 2, 28 Grade 3), and xerostomia (0 Grade 1, 29 Grade 2, 40 Grade 3). Conclusions: Intensity-modulated radiotherapy in the community setting can be accomplished safely and effectively. Systematic internal review systems are recommended for quality control until sufficient experience develops

  13. Comparison of simple and complex liver intensity modulated radiotherapy

    International Nuclear Information System (INIS)

    Intensity-modulated radiotherapy (IMRT) may allow improvement in plan quality for treatment of liver cancer, however increasing radiation modulation complexity can lead to increased uncertainties and requirements for quality assurance. This study assesses whether target coverage and normal tissue avoidance can be maintained in liver cancer intensity-modulated radiotherapy (IMRT) plans by systematically reducing the complexity of the delivered fluence. An optimal baseline six fraction individualized IMRT plan for 27 patients with 45 liver cancers was developed which provided a median minimum dose to 0.5 cc of the planning target volume (PTV) of 38.3 Gy (range, 25.9-59.5 Gy), in 6 fractions, while maintaining liver toxicity risk <5% and maximum luminal gastrointestinal structure doses of 30 Gy. The number of segments was systematically reduced until normal tissue constraints were exceeded while maintaining equivalent dose coverage to 95% of PTV (PTVD95). Radiotherapy doses were compared between the plans. Reduction in the number of segments was achieved for all 27 plans from a median of 48 segments (range 34-52) to 19 segments (range 6-30), without exceeding normal tissue dose objectives and maintaining equivalent PTVD95 and similar PTV Equivalent Uniform Dose (EUD(-20)) IMRT plans with fewer segments had significantly less monitor units (mean, 1892 reduced to 1695, p = 0.012), but also reduced dose conformity (mean, RTOG Conformity Index 1.42 increased to 1.53 p = 0.001). Tumour coverage and normal tissue objectives were maintained with simplified liver IMRT, at the expense of reduced conformity

  14. Residual intensity modulation in resonator fiber optic gyros with sinusoidal wave phase modulation

    Institute of Scientific and Technical Information of China (English)

    Di-qing YING; Qiang LI; Hui-lian MA; Zhong-he JIN

    2014-01-01

    We present how residual intensity modulation (RIM) affects the performance of a resonator fiber optic gyro (R-FOG) through a sinusoidal wave phase modulation technique. The expression for the R-FOG system’s demodulation curve under RIM is obtained. Through numerical simulation with different RIM coefficients and modulation frequencies, we find that a zero deviation is induced by the RIM effect on the demodulation curve, and this zero deviation varies with the RIM coefficient and modulation frequency. The expression for the system error due to this zero deviation is derived. Simulation results show that the RIM-induced error varies with the RIM coefficient and modulation frequency. There also exists optimum values for the RIM coefficient and modulation frequency to totally eliminate the RIM-induced error, and the error increases as the RIM coefficient or modulation frequency deviates from its optimum value;however, in practical situations, these two parameters would not be exactly fixed but fluctuate from their respective optimum values, and a large system error is induced even if there exists a very small deviation of these two critical parameters from their optimum values. Simulation results indicate that the RIM-induced error should be con-sidered when designing and evaluating an R-FOG system.

  15. Intensity-modulated near-infrared spectroscopy: instrument design issues

    Science.gov (United States)

    Alford, Ken; Wickramasinghe, Yappa A.

    2000-05-01

    Tissue oxygenation instruments which rely on phase sensitive detection suffer form phase-amplitude crosstalk, i.e. the phase of the detected signal with respect to a reference signal is dependent on the average intensity of the light entering the photomultiplier tube (PMT). If an instrument that detects the phase of the scattered signal is to yield the phase accuracy required in order to provide useful clinical parameters, quantitative haemoglobin and oxy- haemoglobin concentrations (Hb), and (HbO2) and mixed arterial-venous saturation all sources of phase-amplitude effects must be understood. The phase-amplitude effect has in the past been attributed to the fact that the rise time of the detector decreases with increasing light intensity. In this work an additional phase-amplitude effect in intensity modulated near IR spectroscopy (IMNIRS) instrumentation is studied. The presence of a coherent interfering signal due to low level RF coupling at the detector output will corrupt the phase of the signal of interest and cause a phase-amplitude effect. Under certain conditions a relatively low level interfering RF signal can introduce a significant error in the slope of the phase per unit distance plot. A comparison between measured and modeled phase distortion is presented and ways to reduce the effect discussed. In addition to phase-amplitude effects, the final accuracy of the quantitative measurements made by an IMNIRS instrument depends heavily on the calibration. Calibration of the measured phase and the AC and DC components of the detected light must take into account distortions due to, (a) phase-amplitude crosstalk and system phase offset, (b) detector non-linearities, (c) variation in laser source intensity and phase with time and temperature, (d) optical probe light loss and (e) variations in detector sensitivity. Current instrument performance will be presented and discussed.

  16. Influence of intensity-modulated radiotherapy on tumor regression in nasopharyngeal carcinoma

    International Nuclear Information System (INIS)

    Objective: To retrospectively analyze the influence of intensity-modulated radiotherapy (IMRT) on tumor regression in primary nasopharyngeal carcinoma (NPC). Methods: 272 patients with NPC received radical radiotherapy alone, 196 by IMRT with a total treatment time of 6 weeks, and 76 by bilateral field conventional radiotherapy (CRT) with the total treatment time of 7 weeks. Results: By the end of radiotherapy, the primary tumor and neck lymph node residual rates of the IMRT group were 36.7% and 44.2%, respectively, both significantly higher than those of the GRT group (21.1% and 26.6%, χ2 =6.15, 3.99, P<0.05). Three months after the radiotherapy, residual lesions were observed at the nasopharynx or neck lymph nodes in 12 of the IMRT group, with a residual rate of 6.1%, not significantly different from that of the CRT group (9.2%, 7/76). The 12 residual lesions of the IMRT group all vanished completely 4-9 months after the radiotherapy. Conclusions: There is an obvious difference in regressive mode between IMRT and CRT technique in NPC treatment. At the end of IMRT, the tumor residual rate is slightly increased.However, the delivered dose of gross tumor volume (GTV) is sufficient,and the boost dose should not be delivered indiscreetly. (authors)

  17. Intensity-modulated radiotherapy of nasopharyngeal carcinoma: a comparative treatment planning study of photons and protons

    Directory of Open Access Journals (Sweden)

    Taheri-Kadkhoda Zahra

    2008-01-01

    Full Text Available Abstract Background The aim of this treatment planning study was to investigate the potential advantages of intensity-modulated (IM proton therapy (IMPT compared with IM photon therapy (IMRT in nasopharyngeal carcinoma (NPC. Methods Eight NPC patients were chosen. The dose prescriptions in cobalt Gray equivalent (GyE for gross tumor volumes of the primary tumor (GTV-T, planning target volumes of GTV-T and metastatic (PTV-TN and elective (PTV-N lymph node stations were 72.6 GyE, 66 GyE, and 52.8 GyE, respectively. For each patient, nine coplanar fields IMRT with step-and-shoot technique and 3D spot-scanned three coplanar fields IMPT plans were prepared. Both modalities were planned in 33 fractions to be delivered with a simultaneous integrated boost technique. All plans were prepared and optimized by using the research version of the inverse treatment planning system KonRad (DKFZ, Heidelberg. Results Both treatment techniques were equal in terms of averaged mean dose to target volumes. IMPT plans significantly improved the tumor coverage and conformation (P E were more than doubled by IMRT plans. Conclusion In radiotherapy of NPC patients, three-field IMPT has greater potential than nine-field IMRT with respect to tumor coverage and reduction of the integral dose to OARs and non-specific normal tissues. The practicality of IMPT in NPC deserves further exploration when this technique becomes available on wider clinical scale.

  18. Clinical outcome of adjuvant chemotherapy plus intensity modulated radiotherapy after breast-conserving surgery

    International Nuclear Information System (INIS)

    Objective: To evaluate the efficacy and side effects of adjuvant chemotherapy plus intensity modulated radiotherapy (IMRT) after breast-conserving surgery for stage I and II breast cancer. Methods: After breast-conserving surgery, 108 patients received six cycles of chemotherapy followed by IMRT. The irradiation dose of the whole breast was 50 Gy given by 25 fractions, followed by 10 Gy boost to the tumor bed given by 5 fractions with electron beams. Patients with positive estrone receptor or progesterone receptor were given endocrine treatment, mostly with tamoxifen. Results: The follow-up rate was 100% by December 2007. The number of patients followed-up at 1-, 2- and 3-year was 108,88 and 58. The 1-, 2- and 3-year over survival rates were 100%, 100% and 98%. Three patients had local recurrence. Different degree of dermatitis occurred with good long-term cosmetic results. No severe side effects occurred such as radiation-induced pneumonitis, pulmonary, fibrosis and heart injury. Conclusions: Breast cancer patients treated by adjuvant chemotherapy plus IMRT after breast-conserving surgery have high survival rate and low side-effect rate. The survival quality and local control can be improved. (authors)

  19. Effects of intensity-modulated radiotherapy on human oral microflora

    International Nuclear Information System (INIS)

    This study aimed to evaluate changes in the biodiversity of the oral microflora of patients with head and neck cancer treated with postoperative intensity-modulated radiotherapy (IMRT) or conventional radiotherapy (CRT). Pooled dental plaque samples were collected during the radiation treatment from patients receiving IMRT (n=13) and CRT (n=12). Denaturing gradient gel electrophoresis (DGGE) was used to analyze the temporal variation of these plaque samples. The stimulated and unstimulated salivary flow rates were also compared between IMRT and CRT patients. Reductions in the severity of hyposalivation were observed in IMRT patients compared with CRT patients. We also observed that the temporal stability of the oral ecosystem was significantly higher in the IMRT group (69.96±7.82%) than in the CRT group (51.98±10.45%) (P<0.05). The findings of the present study suggest that IMRT is more conducive to maintaining the relative stability of the oral ecosystem than CRT. (author)

  20. Quantitative shadowgraphy and proton radiography for large intensity modulations

    CERN Document Server

    Kasim, Muhammad Firmansyah; Ratan, Naren; Sadler, James; Chen, Nicholas; Savert, Alexander; Trines, Raoul; Bingham, Robert; Burrows, Philip N; Kaluza, Malte C; Norreys, Peter

    2016-01-01

    Shadowgraphy is a technique widely used to diagnose objects or systems in various fields in physics and engineering. In shadowgraphy, an optical beam is deflected by the object and then the intensity modulation is captured on a screen placed some distance away. However, retrieving quantitative information from the shadowgrams themselves is a challenging task because of the non-linear nature of the process. Here, a novel method to retrieve quantitative information from shadowgrams, based on computational geometry, is presented for the first time. This process can be applied to proton radiography for electric and magnetic field diagnosis in high-energy-density plasmas and has been benchmarked using a toroidal magnetic field as the object, among others. It is shown that the method can accurately retrieve quantitative parameters with error bars less than 10%, even when caustics are present. The method is also shown to be robust enough to process real experimental results with simple pre- and post-processing techn...

  1. New Dosimetry Technologies for Imrt (intensity Modulated Radio Therapy)

    Science.gov (United States)

    Piermattei, A.; Cilla, S.; Pepe, D.; Grimaldi, L.; Craus, M.; Fidanzio, A.; Azario, L.; Dell'Omo, C.; Pasciuti, K.; Viola, P.

    2005-02-01

    An approach to verify the intensity modulated radiation therapy (IMRT) using an anthropomorphic phantom is reported. Step and shoot IMRT was delivered to a Rando phantom and the portal dose computed by a treatment planning system (TPS) was verified by a linear array of liquid ion-chambers. The array was calibrated in terms of dose to water, and supplies dose profiles with a spatial resolution of 1mm. In general the comparison between the experimental portal dose profiles and those computed by the TPS, is needed to detect the inaccuracy sources as the approximation of the calculation algorithms, patient positioning, linac mechanical failures as the incorrect sequences of segment beams. Using a Rando phantom the accuracy level of the TPS algorithm that supplies the portal dose was determined by the γ-index.

  2. Clinical implementation and quality assurance for intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    The paper describes the clinical implementation and quality assurance of intensity modulated radiation therapy (IMRT), based on experience at the Fox Chase Cancer Center, and reviews the procedures for the clinical implementation of the IMRT technique and the requirements for patient immobilization, target delineation, treatment optimization, beam delivery and system administration. The dosimetric requirements and measurement procedures for beam commissioning and dosimetry verification for IMRT are discussed and the details of model based dose calculation for IMRT treatment planning and the potential problems with such dose calculation algorithms are examined. The paper also discusses the effect of beam delivery systems on the actual dose distributions received by the patient and the methods to incorporate such effects in the treatment optimization process. Finally, the use of the Monte Carlo method for dose calculation and treatment verification for IMRT is investigated. (author)

  3. Clinical implementation and quality assurance for intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    This paper describes the clinical implementation and quality assurance (QA) for intensity-modulated radiation therapy (IMRT) based on the experience at Fox Chase Cancer Center, Philadelphia, USA. We will review our procedures for the clinical implementation of the IMRT technique and the requirements for patient immobilization, target delineation, treatment optimization, beam delivery and system administration. We will discuss the dosimetric requirements and measurement procedures for beam commissioning and dosimetry verification for IMRT. We will examine the details of model-based dose calculation for IMRT treatment planning and the potential problems with such dose calculation algorithms. We will discuss the effect of beam delivery systems on the actual dose distributions received by the patients and the methods to incorporate such effects in the treatment optimization process. We will investigate the use of the Monte Carlo method for dose calculation and treatment verification for IMRT

  4. Intensity-Modulated Radiation Therapy for Primary Brain Tumors

    Institute of Scientific and Technical Information of China (English)

    Zhong-min Wang

    2004-01-01

    Radiation therapy has been used to treat primary brain tumors as standard primary and/or adjunctive therapies for decades. It is difficult for conventional radiotherapy to deliver a lethal dose of radiation to the tumors while sparing surrounding normal brain due to complicated structures and multifunction in human brain. With the understanding of radiation physics and computer technology, a number of novel and more precise radiotherapies have been developed in recent years. Intensity modulated radiotherapy (IMRT) is one of these strategies. The use of IMRT in the treatment of primary brain tumors is being increasing nowadays. It shows great promise for some of primary brain tumors and also presents some problems, This review highlights current IMRT in the treatment of mainly primary brain tumors.

  5. Intensity-Modulated Arc Therapy for Pediatric Posterior Fossa Tumors

    International Nuclear Information System (INIS)

    Purpose: To compare intensity-modulated arc therapy (IMAT) to noncoplanar intensity-modulated radiation therapy (IMRT) in the treatment of pediatric posterior fossa tumors. Methods and Materials: Nine pediatric patients with posterior fossa tumors, mean age 9 years (range, 6–15 years), treated using IMRT were chosen for this comparative planning study because of their tumor location. Each patient’s treatment was replanned to receive 54 Gy to the planning target volume (PTV) using five different methods: eight-field noncoplanar IMRT, single coplanar IMAT, double coplanar IMAT, single noncoplanar IMAT, and double noncoplanar IMAT. For each method, the dose to 95% of the PTV was held constant, and the doses to surrounding critical structures were minimized. The different plans were compared based on conformity, total linear accelerator dose monitor units, and dose to surrounding normal tissues, including the entire body, whole brain, temporal lobes, brainstem, and cochleae. Results: The doses to the target and critical structures for the various IMAT methods were not statistically different in comparison with the noncoplanar IMRT plan, with the following exceptions: the cochlear doses were higher and whole brain dose was lower for coplanar IMAT plans; the cochleae and temporal lobe doses were lower and conformity increased for noncoplanar IMAT plans. The advantage of the noncoplanar IMAT plan was enhanced by doubling the treatment arc. Conclusion: Noncoplanar IMAT results in superior treatment plans when compared to noncoplanar IMRT for the treatment of posterior fossa tumors. IMAT should be considered alongside IMRT when treatment of this site is indicated.

  6. Mach-Zehnder Type Annealed Proton Exchange Waveguide and Coplanar Waveguide Modulation Electrode LiNbO3 Intensity Modulator

    Institute of Scientific and Technical Information of China (English)

    HE Jian; ZHU Xue-jun

    2007-01-01

    The characteristics of a conventional LiNbO3 intensity modulator made up of a Mach-Zehnder(MZ) type annealed proton exchange(APE) waveguide and coplanar waveguide(CPW) modulation electrode are presented. The APE waveguide characteristics and their relations with process parameters are analyzed. At the same time, the electrical characteristics of modulation electrode, such as modulation voltage, microwave effective index associated with modulation bandwidth, characteristics impedance, are also investigated in detail.

  7. Intensity Modulated Radiation Therapy. Development of the technique

    International Nuclear Information System (INIS)

    Full text: Introduction: Intensity Modulated Radiation Therapy (IMRT) is a result of advances in computer sciences that allowed the development of new technology related to planning and radiation therapy. IMRT was developed to homogenize the dose in the target volumes and decrease the dose in the surrounding healthy tissue. Using a software with high calculation capacity a simultaneous irradiation with different doses in a given volume is achieved. IMRT is based on internal planning. Material and methods: 628 patients were treated with IMRT in prostate lesions, head and neck, breast, thorax, abdomen and brain since August 2008. The software for IMRT is the XIO CMS and the accelerator used is a Varian Clinac 6 / 100. IMRT requires a first simulation, where immobilization systems are selected (mats, thermoplastic masks, among others) and the demarcation of the target structures, healthy tissue and dose prescription by a tattoo. Images of CT / MRI are merged when necessary. Once the system made the treatment optimization, this one is regulated by modulators. These are produced by numerical control machines from digital files produced by software. In a second modulation the planned irradiation is checked and tattoo is carried out according with this. We have a strict process of quality assurance to assess the viability of the plan before its implementation. We use the Map Check it possible to compare the dose on the central axis and the distribution in the whole plane regarding to that generated by the planning system. From 03/2008 the virtual simulation process was implemented integrating the described stages. Results and Conclusions: IMRT is a complex technique. The meticulous planning, implementation of process and quality control allows the use of this technique in a reliable and secure way. With IMRT we achieved a high level of dose conformation, less irradiation of healthy tissue, lower rates of complications and the dose escalation for some tumors. (authors)

  8. Pitfalls in normalization for intensity-modulated radiation therapy planning

    International Nuclear Information System (INIS)

    Three-dimensional (3D) treatment planning often involves complex combinations of beam energies, treatment fields, and beam modifying devices. Even when a plan is devised that meets many treatment-planning objectives, limitations in the planner's ability to further adjust beam characteristics may require the radiation dose prescription to be normalized to an isodose level that best covers the target volume. While these normalizations help meet the volume coverage goals, they also result in adjustment of the dose delivered to the normal tissues and must be carefully evaluated. Intensity-modulated radiation therapy (IMRT) treatment planning allows combinations of complex dose patterns, in order to achieve the desired treatment planning goals. These dose patterns are created by defining a set of treatment planning objectives and then allowing the treatment planning computer to create intensity patterns, through the use of moving multileaf collimation that will meet the requested goals. Often, when an IMRT treatment plan is created that meets many of the treatment planning goals but falls short of volume coverage requirements, the planner is tempted to apply normalization principles similar to those utilized with 3D treatment planning. Again, these normalizations help meet the volume coverage goals, but unlike 3D planning situations, may result in avoidable delivery of additional doses to the normal tissues. The focus of this study is to evaluate the effect of application of normalization for IMRT planning using multiple patient situations. Recommendations would favor re-optimization over normalization in most planning situations

  9. An efficient dose calculation strategy for intensity modulated proton therapy

    International Nuclear Information System (INIS)

    While intensity-modulated proton therapy (IMPT) has great potential to improve the therapeutic efficacy of radiotherapy, IMPT optimization can be computationally demanding, particularly for large and complex tumors. Here we propose a dose calculation strategy to accelerate IMPT optimization while reducing memory requirements. By using two adjustable threshold parameters, our method separates dose contributions from proton beamlets into major and minor components for each dose voxel. The optimization proceeds with two levels of iterations: in inner iterations, doses are updated in correspondence with changes in beamlet intensities from only the major contributions while keeping the portions from the minor contributions constant; in outer iterations, doses are recalculated exactly by considering both major and minor contributions. Since the number of elements in the influence matrix for major contributions is relatively small, each inner iteration proceeds quickly. Each outer iteration requires a longer computation time, but only a few such iterations are needed. Our study shows that the proposed strategy leads to nearly identical dose distributions as those optimized with the full influence matrix, but reducing computing time by at least a factor of 3 and internal memory requirements by a factor of 10 or more. In addition, we show that the proposed approach could enhance other optimization-related applications such as optimizing beam angles. By using an advanced lung cancer case that would demand large computing resources by conventional optimization approach, we show how our method may potentially help improve IMPT treatment planning in real clinical situations. (note)

  10. Static versus dynamic intensity-modulated radiotherapy: profile of integral dose in carcinoma of the nasopharynx

    International Nuclear Information System (INIS)

    This study is aimed to evaluate the impact of static and dynamic intensity modulated radiotherapy (IMRT) delivery techniques planned with eclipse TPS on the integral dose to the healthy normal tissue surrounding the tumor-bearing area and to the volume receiving doses <5 Gy in patients with carcinoma nasopharynx treated with Simultaneous Integrated Boost IMRT (SIB-IMRT). Ten patients with carcinoma nasopharynx were chosen for this dosimetric study. IMRT plans were generated with 6X using dynamic multileaf collimator (DMLC) and static multileaf collimator (SMLC) with 5, 10 and 15 intensity levels (L). Integral dose, volume receiving 5 Gy, number of monitor units (MU) is compared against DMLC. The mean difference in the MU delivered per fraction between 5, 10 and 15 L SMLC and DMLC was -13.25% (P < 0.001, with paired t test), -11.82% (P < 0.001) and -10.81% (P < 0.001), respectively. The mean difference in the integral dose with 5, 10 and 15 L compared to DMLC was -2.96% (P < 0.001), -2.67% (P = 0.016) and -0.39% (P = 0.430), respectively. However, the difference in low-dose volume (V5Gy) was statistically insignificant with mean difference of 0.60% (P = 0.23), 1.18% (P = 0.017) and 1.70% (P = 0.078), respectively for 5, 10 and 15 L compared to DMLC. Our results show that while choosing the IMRT delivery technique using conventional MLC the concerns about integral dose and volume receiving very low doses such as 5 Gy can be ignored. (author)

  11. Clinical Implementation of Intensity Modulated Proton Therapy for Thoracic Malignancies

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Joe Y., E-mail: jychang@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Li, Heng; Zhu, X. Ronald [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Liao, Zhongxing; Zhao, Lina [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Liu, Amy [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Li, Yupeng [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Applied Research, Varian Medical Systems, Palo Alto, California (United States); Sahoo, Narayan; Poenisch, Falk [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Gomez, Daniel R. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Wu, Richard; Gillin, Michael [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Zhang, Xiaodong, E-mail: xizhang@mdanderson.org [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

    2014-11-15

    Purpose: Intensity modulated proton therapy (IMPT) can improve dose conformality and better spare normal tissue over passive scattering techniques, but range uncertainties complicate its use, particularly for moving targets. We report our early experience with IMPT for thoracic malignancies in terms of motion analysis and management, plan optimization and robustness, and quality assurance. Methods and Materials: Thirty-four consecutive patients with lung/mediastinal cancers received IMPT to a median 66 Gy(relative biological equivalence [RBE]). All patients were able to undergo definitive radiation therapy. IMPT was used when the treating physician judged that IMPT conferred a dosimetric advantage; all patients had minimal tumor motion (<5 mm) and underwent individualized tumor-motion dose-uncertainty analysis and 4-dimensional (4D) computed tomographic (CT)-based treatment simulation and motion analysis. Plan robustness was optimized by using a worst-case scenario method. All patients had 4D CT repeated simulation during treatment. Results: IMPT produced lower mean lung dose (MLD), lung V{sub 5} and V{sub 20}, heart V{sub 40}, and esophageal V{sub 60} than did IMRT (P<.05) and lower MLD, lung V{sub 20}, and esophageal V{sub 60} than did passive scattering proton therapy (PSPT) (P<.05). D{sub 5} to the gross tumor volume and clinical target volume was higher with IMPT than with intensity modulated radiation therapy or PSPT (P<.05). All cases were analyzed for beam-angle-specific motion, water-equivalent thickness, and robustness. Beam angles were chosen to minimize the effect of respiratory motion and avoid previously treated regions, and the maximum deviation from the nominal dose-volume histogram values was kept at <5% for the target dose and met the normal tissue constraints under a worst-case scenario. Patient-specific quality assurance measurements showed that a median 99% (range, 95% to 100%) of the pixels met the 3% dose/3 mm distance criteria for the

  12. Benchmarking Dosimetric Quality Assessment of Prostate Intensity-Modulated Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Senthi, Sashendra, E-mail: sasha.senthi@petermac.org [Division of Radiation Oncology, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Gill, Suki S. [Division of Radiation Oncology, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Haworth, Annette; Kron, Tomas; Cramb, Jim [Department of Physical Sciences, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Rolfo, Aldo [Radiation Therapy Services, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Thomas, Jessica [Biostatistics and Clinical Trials, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Duchesne, Gillian M. [Division of Radiation Oncology, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia); Hamilton, Christopher H.; Joon, Daryl Lim [Radiation Oncology Department, Austin Repatriation Hospital, Heidelberg, VIC (Australia); Bowden, Patrick [Radiation Oncology Department, Tattersall' s Cancer Center, East Melbourne, VIC (Australia); Foroudi, Farshad [Division of Radiation Oncology, Peter MacCallum Cancer Center, East Melbourne, VIC (Australia)

    2012-02-01

    Purpose: To benchmark the dosimetric quality assessment of prostate intensity-modulated radiotherapy and determine whether the quality is influenced by disease or treatment factors. Patients and Methods: We retrospectively analyzed the data from 155 consecutive men treated radically for prostate cancer using intensity-modulated radiotherapy to 78 Gy between January 2007 and March 2009 across six radiotherapy treatment centers. The plan quality was determined by the measures of coverage, homogeneity, and conformity. Tumor coverage was measured using the planning target volume (PTV) receiving 95% and 100% of the prescribed dose (V{sub 95%} and V{sub 100%}, respectively) and the clinical target volume (CTV) receiving 95% and 100% of the prescribed dose. Homogeneity was measured using the sigma index of the PTV and CTV. Conformity was measured using the lesion coverage factor, healthy tissue conformity index, and the conformity number. Multivariate regression models were created to determine the relationship between these and T stage, risk status, androgen deprivation therapy use, treatment center, planning system, and treatment date. Results: The largest discriminatory measurements of coverage, homogeneity, and conformity were the PTV V{sub 95%}, PTV sigma index, and conformity number. The mean PTV V{sub 95%} was 92.5% (95% confidence interval, 91.3-93.7%). The mean PTV sigma index was 2.10 Gy (95% confidence interval, 1.90-2.20). The mean conformity number was 0.78 (95% confidence interval, 0.76-0.79). The treatment center independently influenced the coverage, homogeneity, and conformity (all p < .0001). The planning system independently influenced homogeneity (p = .038) and conformity (p = .021). The treatment date independently influenced the PTV V{sub 95%} only, with it being better at the start (p = .013). Risk status, T stage, and the use of androgen deprivation therapy did not influence any aspect of plan quality. Conclusion: Our study has benchmarked measures

  13. Benchmarking Dosimetric Quality Assessment of Prostate Intensity-Modulated Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To benchmark the dosimetric quality assessment of prostate intensity-modulated radiotherapy and determine whether the quality is influenced by disease or treatment factors. Patients and Methods: We retrospectively analyzed the data from 155 consecutive men treated radically for prostate cancer using intensity-modulated radiotherapy to 78 Gy between January 2007 and March 2009 across six radiotherapy treatment centers. The plan quality was determined by the measures of coverage, homogeneity, and conformity. Tumor coverage was measured using the planning target volume (PTV) receiving 95% and 100% of the prescribed dose (V95% and V100%, respectively) and the clinical target volume (CTV) receiving 95% and 100% of the prescribed dose. Homogeneity was measured using the sigma index of the PTV and CTV. Conformity was measured using the lesion coverage factor, healthy tissue conformity index, and the conformity number. Multivariate regression models were created to determine the relationship between these and T stage, risk status, androgen deprivation therapy use, treatment center, planning system, and treatment date. Results: The largest discriminatory measurements of coverage, homogeneity, and conformity were the PTV V95%, PTV sigma index, and conformity number. The mean PTV V95% was 92.5% (95% confidence interval, 91.3–93.7%). The mean PTV sigma index was 2.10 Gy (95% confidence interval, 1.90–2.20). The mean conformity number was 0.78 (95% confidence interval, 0.76–0.79). The treatment center independently influenced the coverage, homogeneity, and conformity (all p 95% only, with it being better at the start (p = .013). Risk status, T stage, and the use of androgen deprivation therapy did not influence any aspect of plan quality. Conclusion: Our study has benchmarked measures of coverage, homogeneity, and conformity for the treatment of prostate cancer using IMRT. The differences seen between centers and planning systems and the coverage deterioration

  14. Hypoxia imaging with [F-18] FMISO-PET in head and neck cancer: Potential for guiding intensity modulated radiation therapy in overcoming hypoxia-induced treatment resistance

    International Nuclear Information System (INIS)

    Background and purpose: Positron emission tomography (PET) imaging with [F-18] fluoromisonidazole (FMISO) has been validated as a hypoxic tracer . Head and neck cancer exhibits hypoxia, inducing aggressive biologic traits that impart resistance to treatment. Delivery of modestly higher radiation doses to tumors with stable areas of chronic hypoxia can improve tumor control . Advanced radiation treatment planning (RTP) and delivery techniques such as intensity modulated radiation therapy (IMRT) can deliver higher doses to a small volume without increasing morbidity. We investigated the utility of co-registered FMISO-PET and CT images to develop clinically feasible RTPs with higher tumor control probabilities (TCP). Materials and methods: FMISO-PET images were used to determine hypoxic sub-volumes for boost planning. Example plans were generated for 10 of the patients in the study who exhibited significant hypoxia. We created an IMRT plan for each patient with a simultaneous integrated boost (SIB) to the hypoxic sub-volumes. We also varied the boost for two patients. Result: A significant (mean 17%, median 15%) improvement in TCP is predicted when the modest additional boost dose to the hypoxic sub-volume is included. Conclusion: Combined FMISO-PET imaging and IMRT planning permit delivery of higher doses to hypoxic regions, increasing the predicted TCP (mean 17%) without increasing expected complications.

  15. Intensity modulated radiation therapy (IMRT) : is it Nirvana?

    International Nuclear Information System (INIS)

    Full text: Intensity modulated radiation therapy generally implies the use of inverse planning using preselected organ dose constraints and dose volume histogram analysis. Then modulated beams are created by multi leaf collimator (MLC) sequences. Because of the complexity of planning and delivery dosimetry verification is essential. With the pinnacle radiotherapy planning computer (RTPC) an inverse planned continuous solution is created using multiple iterations of a weighted gradient optimisation method. Then a step and shoot MLC sequence solution is created using K-means clustering and this solution is then forward computed using the accurate collapsed cone convolution calculation. There is a beams eye view planar dose tool on the RTPC. Therefore dose profiles at any depth for each individual beam can be compared with film maps taken in the same real geometry on the linear accelerator. The film is scanned using a Vidar film scanner and density to dose conversion is achieved by fitting an exponential function to the calibration films. Three dimensional dose profile maps have been created to compare film dose profiles with RTPC dose profiles. The dose variation between the inverse planned distribution and the discrete forward computed sequence can be selected, for example a 5% match leads to about 7 segments and a 2% match leads to about 20 segments per field. For each individual modulated beam in a seven field prostate plan (2Gy to isocentre) the dose in each field typically varies from 15 cGy to 25 cGy at 10 cm depth. The profiles often tend to show 'pointy edges' with the maximum dose applied to each edge of the beam profile. MLC Matchline errors of 15% have been observed on the verification films, however as the dose contribution from each beam is low the actual dose difference in the matchline is typically only 2 cGy. Because of the complexity of IMRT dose calculations traditional plan manual checks become impossible and alternate QA tools need to be developed

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

    International Nuclear Information System (INIS)

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

  17. Intensity-Modulated Radiation Therapy in Childhood Ependymoma

    International Nuclear Information System (INIS)

    Purpose: To determine the patterns of failure after intensity-modulated radiation therapy (IMRT) for localized intracranial ependymoma. Methods and Materials: From 1994 to 2005, 22 children with pathologically proven, localized, intracranial ependymoma were treated with adjuvant IMRT. Of the patients, 12 (55%) had an infratentorial tumor and 14 (64%) had anaplastic histology. Five patients had a subtotal resection (STR), as evidenced by postoperative magnetic resonance imaging. The clinical target volume encompassed the tumor bed and any residual disease plus margin (median dose 54 Gy). Median follow-up for surviving patients was 39.8 months. Results: The 3-year overall survival rate was 87% ± 9%. The 3-year local control rate was 68% ± 12%. There were six local recurrences, all in the high-dose region of the treatment field. Median time to recurrence was 21.7 months. Of the 5 STR patients, 4 experienced recurrence and 3 died. Patients with a gross total resection had significantly better local control (p = 0.024) and overall survival (p = 0.008) than those with an STR. At last follow-up, no patient had developed visual loss, brain necrosis, myelitis, or a second malignancy. Conclusions: Treatment with IMRT provides local control and survival rates comparable with those in historic publications using larger treatment volumes. All failures were within the high-dose region, suggesting that IMRT does not diminish local control. The degree of surgical resection was shown to be significant for local control and survival

  18. Norwegian Oncologists' Expectations of Intensity-modulated Radiotherapy

    International Nuclear Information System (INIS)

    Although intensity-modulated radiotherapy (IMRT) may increase the therapeutic ratio of radiotherapy for a range of malignancies, only a few IMRT treatments have yet been performed in the Nordic countries. The scores derived from a national survey to assess Norwegian oncologists' expectations of IMRT are presented. A questionnaire was distributed to all consultants in oncology at Norwegian radiotherapy clinics. Summary scores of daily general radiotherapy workload (DGRTW), acquaintance with IMRT (AI) and expectations of IMRT (EI) were derived. Thirty-nine questionnaires (67%) were returned from a total of 58 oncologists. The oncologists' scores on the AI scale (mean score: 7.5 out of 21) were rather low. Their AI scores were found to be positively correlated with their DGRTW. Higher scores on the EI scale were documented (mean score: 6.2 out of 14): 15 oncologists (39%) rated IMRT as one of the three major contributors to potentially increased cancer survival. Oncologists treating patients with prostate, head and neck, gastrointestinal and CNS tumours had higher EI scores than the other oncologists (7.7 vs. 5.1; p=0.01). The Norwegian radiation oncologists' expectations of IMRT are high in terms of both the potential clinical benefit and the rate of implementation. This should encourage the radiotherapy communities to continue (or rapidly initiate) their efforts in providing the routines required for safe implementation of IMRT

  19. Applications of two-step intensity modulated arc therapy

    International Nuclear Information System (INIS)

    Purpose: Organs at risk sometimes are surrounded by the target volume. At a first glance it seems to be impossible, to spare the organs at risk, i.e. the spinal cord, without underdosage of parts of the concave target volume. A fast method called ''two-step intensity modulated arc therapy'' (two-step IMAT) will be shown that avoids underdosage in the target volume near such organs at risk. Materials and Methods: Simple rotational techniques reduce the dose to the surrounded organ, however, the blocking of the organ at risk spoils the homogeneity of dose in the target volume in the vicinity of the organ. A further narrow rotation field, tangential to the concave part of the target volume, increases the dose there and homogenizes the dose distribution without deteriorating the dose in the organ at risk significantly. Results: Some cases show that the two-step IMAT and its modifications guarantee a sufficient dose homogeneity in the target volume surrounding an organ at risk. Besides basic theoretical considerations exemplary solutions for head and neck tumors, tumors adjacent to the spinal cord and mamma carcinoma of patients with extremely arched chest are demonstrated. Conclusion: Double rotation techniques can provide sufficient dose homogeneity for concave target volumes with excellent sparing of the surrounded organ at risk. They are not time consuming and can be used until IMRT will be applied routinely with adequate time load and effort. (orig.)

  20. Intensity modulated radiation therapy (IMRT) in prostate cancer

    International Nuclear Information System (INIS)

    Radiotherapy is an established standard in radical treatment of localized prostate cancer: During conventional radiotherapy total doses of 70 Gy are applied as the safe upper limit due to an acceptable risk of normal tissue complications within the treated volume. Several clinical studies revealed that doses higher than prescribed in conventional radiotherapy may be desirable to improve local control in prostate cancer: Technical developments in radiotherapy, together with the implementation of conformal techniques, have allowed dose escalation within tumor volume while sparing surrounding normal tissues. With the introduction of intensity modulated radiation therapy (IMRT) it is expected to escalate the dose to the target yet further; while maintaining the risk of normal tissue complications or to reduce the dose within critical structures without comprising the dose to the target. The paper presents the spectrum of bibliography regarding the use of IMRT in computer treatment planning of prostate cases. The results of clinical trials and studies concerning IMRT in the management of prostate cancer are presented. (author)

  1. Dose-painting intensity-modulated proton therapy for intermediate- and high-risk meningioma

    International Nuclear Information System (INIS)

    Newly diagnosed WHO grade II-III or any WHO grade recurrent meningioma exhibit an aggressive behavior and thus are considered as high- or intermediate risk tumors. Given the unsatisfactory rates of disease control and survival after primary or adjuvant radiation therapy, optimization of treatment strategies is needed. We investigated the potential of dose-painting intensity-modulated proton beam-therapy (IMPT) for intermediate- and high-risk meningioma. Imaging data from five patients undergoing proton beam-therapy were used. The dose-painting target was defined using [68]Ga-[1,4,7,10-tetraazacyclododecane tetraacetic acid]– d-Phe1,Tyr3-octreotate ([68]Ga-DOTATATE)-positron emission tomography (PET) in target delineation. IMPT and photon intensity-modulated radiation therapy (IMRT) treatment plans were generated for each patient using an in-house developed treatment planning system (TPS) supporting spot-scanning technology and a commercial TPS, respectively. Doses of 66 Gy (2.2 Gy/fraction) and 54 Gy (1.8 Gy/fraction) were prescribed to the PET-based planning target volume (PTVPET) and the union of PET- and anatomical imaging-based PTV, respectively, in 30 fractions, using simultaneous integrated boost. Dose coverage of the PTVsPET was equally good or slightly better in IMPT plans: dose inhomogeneity was 10 ± 3% in the IMPT plans vs. 13 ± 1% in the IMRT plans (p = 0.33). The brain Dmean and brainstem D50 were small in the IMPT plans: 26.5 ± 1.5 Gy(RBE) and 0.002 ± 0.0 Gy(RBE), respectively, vs. 29.5 ± 1.5 Gy (p = 0.001) and 7.5 ± 11.1 Gy (p = 0.02) for the IMRT plans, respectively. The doses delivered to the optic structures were also decreased with IMPT. Dose-painting IMPT is technically feasible using currently available planning tools and resulted in dose conformity of the dose-painted target comparable to IMRT with a significant reduction of radiation dose delivered to the brain, brainstem and optic apparatus. Dose escalation with IMPT may improve tumor

  2. Contribution of three-dimensional conformal intensity-modulated radiation therapy for women affected by bulky stage II supradiaphragmatic Hodgkin disease

    OpenAIRE

    Antoni, Delphine; Natarajan-Ame, Shanti; Meyer, Philippe; Niederst, Claudine; Bourahla, Khalil; Noel, Georges

    2013-01-01

    Purpose To analyze the outcome and dose distribution of intensity-modulated radiation therapy (IMRT) by helical tomotherapy in women treated for large supradiaphragmatic Hodgkin’s disease. Material and methods A total of 13 patients received adjuvant radiation at a dose of 30 Gy to the initially involved sites with a boost of 6 Gy to those areas suspected of harboring residual disease on the simulation CT scan. Results With a median follow-up of 23 months, the two-year progression-free surviv...

  3. Intensity modulated neutron radiotherapy optimization by photon proxy

    International Nuclear Information System (INIS)

    Purpose: Introducing intensity modulation into neutron radiotherapy (IMNRT) planning has the potential to mitigate some normal tissue complications seen in past neutron trials. While the hardware to deliver IMNRT plans has been in use for several years, until recently the IMNRT planning process has been cumbersome and of lower fidelity than conventional photon plans. Our in-house planning system used to calculate neutron therapy plans allows beam weight optimization of forward planned segments, but does not provide inverse optimization capabilities. Commercial treatment planning systems provide inverse optimization capabilities, but currently cannot model our neutron beam. Methods: We have developed a methodology and software suite to make use of the robust optimization in our commercial planning system while still using our in-house planning system to calculate final neutron dose distributions. Optimized multileaf collimator (MLC) leaf positions for segments designed in the commercial system using a 4 MV photon proxy beam are translated into static neutron ports that can be represented within our in-house treatment planning system. The true neutron dose distribution is calculated in the in-house system and then exported back through the MATLAB software into the commercial treatment planning system for evaluation. Results: The planning process produces optimized IMNRT plans that reduce dose to normal tissue structures as compared to 3D conformal plans using static MLC apertures. The process involves standard planning techniques using a commercially available treatment planning system, and is not significantly more complex than conventional IMRT planning. Using a photon proxy in a commercial optimization algorithm produces IMNRT plans that are more conformal than those previously designed at our center and take much less time to create. Conclusions: The planning process presented here allows for the optimization of IMNRT plans by a commercial treatment planning

  4. Dosimetrically Triggered Adaptive Intensity Modulated Radiation Therapy for Cervical Cancer

    International Nuclear Information System (INIS)

    Purpose: The widespread use of intensity modulated radiation therapy (IMRT) for cervical cancer has been limited by internal target and normal tissue motion. Such motion increases the risk of underdosing the target, especially as planning margins are reduced in an effort to reduce toxicity. This study explored 2 adaptive strategies to mitigate this risk and proposes a new, automated method that minimizes replanning workload. Methods and Materials: Thirty patients with cervical cancer participated in a prospective clinical study and underwent pretreatment and weekly magnetic resonance (MR) scans over a 5-week course of daily external beam radiation therapy. Target volumes and organs at risk (OARs) were contoured on each of the scans. Deformable image registration was used to model the accumulated dose (the real dose delivered to the target and OARs) for 2 adaptive replanning scenarios that assumed a very small PTV margin of only 3 mm to account for setup and internal interfractional motion: (1) a preprogrammed, anatomy-driven midtreatment replan (A-IMRT); and (2) a dosimetry-triggered replan driven by target dose accumulation over time (D-IMRT). Results: Across all 30 patients, clinically relevant target dose thresholds failed for 8 patients (27%) if 3-mm margins were used without replanning. A-IMRT failed in only 3 patients and also yielded an additional small reduction in OAR doses at the cost of 30 replans. D-IMRT assured adequate target coverage in all patients, with only 23 replans in 16 patients. Conclusions: A novel, dosimetry-triggered adaptive IMRT strategy for patients with cervical cancer can minimize the risk of target underdosing in the setting of very small margins and substantial interfractional motion while minimizing programmatic workload and cost

  5. Intensity Modulated Radiation Therapy With Dose Painting to Treat Rhabdomyosarcoma

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Joanna C.; Dharmarajan, Kavita V. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Wexler, Leonard H. [Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); La Quaglia, Michael P. [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Happersett, Laura [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Wolden, Suzanne L., E-mail: woldens@mskcc.org [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

    2012-11-01

    Purpose: To examine local control and patterns of failure in rhabdomyosarcoma patients treated with intensity modulated radiation therapy (RT) with dose painting (DP-IMRT). Patients and Methods: A total of 41 patients underwent DP-IMRT with chemotherapy for definitive treatment. Nineteen also underwent surgery with or without intraoperative RT. Fifty-six percent had alveolar histologic features. The median interval from beginning chemotherapy to RT was 17 weeks (range, 4-25). Very young children who underwent second-look procedures with or without intraoperative RT received reduced doses of 24-36 Gy in 1.4-1.8-Gy fractions. Young adults received 50.4 Gy to the primary tumor and lower doses of 36 Gy in 1.8-Gy fractions to at-risk lymph node chains. Results: With 22 months of median follow-up, the actuarial local control rate was 90%. Patients aged {<=}7 years who received reduced overall and fractional doses had 100% local control, and young adults had 79% (P=.07) local control. Three local failures were identified in young adults whose primary target volumes had received 50.4 Gy in 1.8-Gy fractions. Conclusions: DP-IMRT with lower fractional and cumulative doses is feasible for very young children after second-look procedures with or without intraoperative RT. DP-IMRT is also feasible in adolescents and young adults with aggressive disease who would benefit from prophylactic RT to high-risk lymph node chains, although dose escalation might be warranted for improved local control. With limited follow-up, it appears that DP-IMRT produces local control rates comparable to those of sequential IMRT in patients with rhabdomyosarcoma.

  6. Intensity modulated radiotherapy for elderly bladder cancer patients

    International Nuclear Information System (INIS)

    To review our experience and evaluate treatment planning using intensity-modulated radiotherapy (IMRT) and helical tomotherapy (HT) for the treatment of elderly patients with bladder cancer. From November 2006 through November 2009, we enrolled 19 elderly patients with histologically confirmed bladder cancer, 9 in the IMRT and 10 in the HT group. The patients received 64.8 Gy to the bladder with or without concurrent chemotherapy. Conventional 4-field 'box' pelvic radiation therapy (2DRT) plans were generated for comparison. The median patient age was 80 years old (range, 65-90 years old). The median survival was 21 months (5 to 26 months). The actuarial 2-year overall survival (OS) for the IMRT vs. the HT group was 26.3% vs .37.5%, respectively; the corresponding values for disease-free survival were 58.3% vs. 83.3%, respectively; for locoregional progression-free survival (LRPFS), the values were 87.5% vs. 83.3%, respectively; and for metastases-free survival, the values were 66.7% vs. 60.0%, respectively. The 2-year OS rates for T1, 2 vs. T3, 4 were 66.7% vs. 35.4%, respectively (p = 0.046). The 2-year OS rate was poor for those whose RT completion time greater than 8 weeks when compared with the RT completed within 8 wks (37.9% vs. 0%, p = 0.004). IMRT and HT provide good LRPFS with tolerable toxicity for elderly patients with invasive bladder cancer. IMRT and HT dosimetry and organ sparing capability were superior to that of 2DRT, and HT provides better sparing ability than IMRT. The T category and the RT completion time influence OS rate

  7. Accommodation of couch constraints for coplanar intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    Purpose: Three treatment couches, henceforth referred to as the standard, the variable standard and the C-arm couch, each based on a different supporting frame system, were investigated for their suitability for the delivery of a high number of coplanar beams (≥5) as may be required for intensity-modulated radiation therapy treatments. Materials and methods: A number of equispaced beam arrangements (five to nine) were examined in combination with two circular target sizes (diameter 6 and 10 cm) at different locations within an elliptical body on the investigated couches, resulting in 70 different plans per couch. A rule based advisory system determined possible intersections of the beam paths with the supporting frames of the respective treatment couch and suggested a suitable constellation for the supporting frames. In cases of intersection, a beam-couch collision was eliminated by minimal rotation of the beams from the initial equispaced beam arrangement. To investigate the effect of a rotation of the posterior-oblique beams for five, seven and nine initially equispaced beams by an angle of 10 deg., a prostate plan was generated and compared with equispaced beam arrangement. Results: Initial beam paths intersected with the standard couch in 63% of the plans, necessitating a rotation of one or two beams. It was necessary to modify the beam angles in 34% of the cases on the variable standard couch to avoid an intersection of the beams with the couch. All the plans would have been delivered satisfactorily on the C-arm couch without a rotation of beams. Simulation studies showed that the dose distribution for a prostate treatment could be affected significantly, but not detrimentally, by the rotation of the two posterior-oblique beam orientations by an angle of 10 deg

  8. Dosimetrically Triggered Adaptive Intensity Modulated Radiation Therapy for Cervical Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Karen [Department of Radiation Oncology, Liverpool Hospital, Sydney (Australia); Stewart, James [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario (Canada); Kelly, Valerie [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Xie, Jason [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Brock, Kristy K. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Moseley, Joanne [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Cho, Young-Bin; Fyles, Anthony [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Lundin, Anna; Rehbinder, Henrik; Löf, Johan [RaySearch Laboratories AB, Stockholm (Sweden); Jaffray, David A. [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario (Canada); Techna Institute for the Advancement of Technology for Health, Toronto, Ontario (Canada); Milosevic, Michael, E-mail: mike.milosevic@rmp.uhn.ca [Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario (Canada)

    2014-09-01

    Purpose: The widespread use of intensity modulated radiation therapy (IMRT) for cervical cancer has been limited by internal target and normal tissue motion. Such motion increases the risk of underdosing the target, especially as planning margins are reduced in an effort to reduce toxicity. This study explored 2 adaptive strategies to mitigate this risk and proposes a new, automated method that minimizes replanning workload. Methods and Materials: Thirty patients with cervical cancer participated in a prospective clinical study and underwent pretreatment and weekly magnetic resonance (MR) scans over a 5-week course of daily external beam radiation therapy. Target volumes and organs at risk (OARs) were contoured on each of the scans. Deformable image registration was used to model the accumulated dose (the real dose delivered to the target and OARs) for 2 adaptive replanning scenarios that assumed a very small PTV margin of only 3 mm to account for setup and internal interfractional motion: (1) a preprogrammed, anatomy-driven midtreatment replan (A-IMRT); and (2) a dosimetry-triggered replan driven by target dose accumulation over time (D-IMRT). Results: Across all 30 patients, clinically relevant target dose thresholds failed for 8 patients (27%) if 3-mm margins were used without replanning. A-IMRT failed in only 3 patients and also yielded an additional small reduction in OAR doses at the cost of 30 replans. D-IMRT assured adequate target coverage in all patients, with only 23 replans in 16 patients. Conclusions: A novel, dosimetry-triggered adaptive IMRT strategy for patients with cervical cancer can minimize the risk of target underdosing in the setting of very small margins and substantial interfractional motion while minimizing programmatic workload and cost.

  9. Prospective Trial of Accelerated Partial Breast Intensity-Modulated Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To examine the feasibility and acute toxicities of an accelerated, partial breast, intensity-modulated radiotherapy (IMRT) protocol. Methods and Materials: Between February 2004 and August 2005, 55 patients with Stage I breast cancer and initial follow-up were enrolled at four facilities on a HealthONE and Western institutional review board-approved accelerated partial breast IMRT protocol. All patients were treated in 10 equal fractions delivered twice daily within 5 consecutive days. The first 7 patients were treated to 34 Gy, and the remaining 48 patients were treated to 38.5 Gy. Results: The median follow-up after IMRT was 10 months (range, <1-19) and after diagnosis was 11.5 months (range, 2-21). No local or distant recurrences developed. The T stage distribution was as follows: T1a in 11 patients, T1b in 24, and T1c in 20. The median tumor size was 9 mm (range, 1-20 mm). Breast cosmesis was judged by the patient as poor by 2, good by 12, and excellent by 40 (1 patient was legally blind) and by the physician as poor for 1, good for 10, and excellent for 44 patients. Breast pain, as judged by patient, was none in 34, mild in 19, moderate in 2, and severe in 0 patients. There was a single report of telangiectasia but no incidents of significant edema. Compared with historic controls for whom three-dimensional treatment planning techniques were used, IMRT provided similar dose delivery to the target while reducing the volume of normal breast included in the 100%, 75%, and 50% isodose lines. Conclusion: This initial report prospectively explored the feasibility of accelerated partial breast IMRT. After short-term follow-up, the dose delivery and clinical outcomes were very acceptable. We believe this regimen deserves additional investigation under institutional review board guidance

  10. Hypofractionated Dose-Painting Intensity Modulated Radiation Therapy with Chemotherapy for Nasopharyngeal Carcinoma, a Prospective Trial

    Science.gov (United States)

    Bakst, Richard L.; Lee, Nancy; Pfister, David G.; Zelefsky, Michael J.; Hunt, Margie A.; Kraus, Dennis H.; Wolden, Suzanne L.

    2010-01-01

    Purpose To evaluate the feasibility of Dose-Painting Intensity-Modulated Radiation Therapy (DP-IMRT) with a hypofractionated regimen to treat nasopharyngeal carcinoma (NPC) with concomitant toxicity reduction. Materials/Methods From 10/02–4/07, 25 newly diagnosed NPC patients were enrolled on a prospective trial. DP-IMRT was prescribed to deliver 70.2 Gy using 2.34 Gy fractions to the gross tumor volume for the primary and nodal sites while simultaneously delivering 54 Gy in 1.8 Gy fractions to regions at risk of microscopic disease. Patients received concurrent and adjuvant platin–based chemotherapy similar to the Intergroup 0099 trial. Results Patient/disease characteristics: median age 46; 44% Asian; 68% male; 76% WHO III; 20% T1, 52% T2, 16% T3, 12% T4; 20% N0, 36% N1, 36% N2, 8% N3. With median follow-up of 33 months, 3-year local control was 91%, regional control was 91%, freedom from distant metastases was 91%, and overall survival was 89%. The average mean dose to each cochlea was 43 Gy. With median audiogram follow-up of 14 months, only one patient had clinically significant (grade 3) hearing loss. 12% of patients developed temporal lobe necrosis; one patient required surgical resection. Conclusions Preliminary findings using a hypofractionated DP-IMRT regimen demonstrated that local control, freedom from distant metastases and overall survival compared favorably to other series of IMRT and chemotherapy. The highly conformal boost to the tumor bed resulted low rates of severe ototoxicity (Grade 3–4). However, the incidence of in-field brain radiation necrosis indicates that 2.34 Gy per fraction is not safe in this setting. PMID:20605352

  11. Intensity-modulated radiotherapy for breast and head-and-neck cancer

    NARCIS (Netherlands)

    Asselen, B. (Bram) van

    2003-01-01

    Intensity-modulated radiotherapy (IMRT) is an advanced form of radiotherapy; the beam intensity can thereby be modulated. IMRT can be used to create a highly conformal dose distribution around a tumor, while reducing the dose to the surrounding normal tissue. IMRT can also be used to deliver a heter

  12. Intensity Modulated Radiation Therapy Dose Painting for Localized Prostate Cancer Using {sup 11}C-choline Positron Emission Tomography Scans

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Joe H. [Radiation Oncology Centre, Austin Health, Victoria (Australia); University of Melbourne, Victoria (Australia); Lim Joon, Daryl [Radiation Oncology Centre, Austin Health, Victoria (Australia); Lee, Sze Ting [University of Melbourne, Victoria (Australia); Centre for PET, Austin Health, Victoria (Australia); Ludwig Institute for Cancer Research, Victoria (Australia); Gong, Sylvia J. [Centre for PET, Austin Health, Victoria (Australia); Anderson, Nigel J. [Radiation Oncology Centre, Austin Health, Victoria (Australia); Scott, Andrew M. [University of Melbourne, Victoria (Australia); Centre for PET, Austin Health, Victoria (Australia); Ludwig Institute for Cancer Research, Victoria (Australia); Davis, Ian D. [University of Melbourne, Victoria (Australia); Ludwig Institute for Cancer Research, Victoria (Australia); Clouston, David [Focus Pathology, Victoria (Australia); Bolton, Damien [University of Melbourne, Victoria (Australia); Department of Urology, Austin Health, Victoria (Australia); Hamilton, Christopher S. [Radiation Oncology Centre, Austin Health, Victoria (Australia); Khoo, Vincent, E-mail: vincent.khoo@rmh.nhs.uk [Radiation Oncology Centre, Austin Health, Victoria (Australia); University of Melbourne, Victoria (Australia); Department of Clinical Oncology, Royal Marsden Hospital and Institute of Cancer Research, London (United Kingdom)

    2012-08-01

    Purpose: To demonstrate the technical feasibility of intensity modulated radiation therapy (IMRT) dose painting using {sup 11}C-choline positron emission tomography PET scans in patients with localized prostate cancer. Methods and Materials: This was an RT planning study of 8 patients with prostate cancer who had {sup 11}C-choline PET scans prior to radical prostatectomy. Two contours were semiautomatically generated on the basis of the PET scans for each patient: 60% and 70% of the maximum standardized uptake values (SUV{sub 60%} and SUV{sub 70%}). Three IMRT plans were generated for each patient: PLAN{sub 78}, which consisted of whole-prostate radiation therapy to 78 Gy; PLAN{sub 78-90}, which consisted of whole-prostate RT to 78 Gy, a boost to the SUV{sub 60%} to 84 Gy, and a further boost to the SUV{sub 70%} to 90 Gy; and PLAN{sub 72-90}, which consisted of whole-prostate RT to 72 Gy, a boost to the SUV{sub 60%} to 84 Gy, and a further boost to the SUV{sub 70%} to 90 Gy. The feasibility of these plans was judged by their ability to reach prescription doses while adhering to published dose constraints. Tumor control probabilities based on PET scan-defined volumes (TCP{sub PET}) and on prostatectomy-defined volumes (TCP{sub path}), and rectal normal tissue complication probabilities (NTCP) were compared between the plans. Results: All plans for all patients reached prescription doses while adhering to dose constraints. TCP{sub PET} values for PLAN{sub 78}, PLAN{sub 78-90}, and PLAN{sub 72-90} were 65%, 97%, and 96%, respectively. TCP{sub path} values were 71%, 97%, and 89%, respectively. Both PLAN{sub 78-90} and PLAN{sub 72-90} had significantly higher TCP{sub PET} (P=.002 and .001) and TCP{sub path} (P<.001 and .014) values than PLAN{sub 78}. PLAN{sub 78-90} and PLAN{sub 72-90} were not significantly different in terms of TCP{sub PET} or TCP{sub path}. There were no significant differences in rectal NTCPs between the 3 plans. Conclusions: IMRT dose painting for

  13. Dynamic optical modulation of an electron beam on a photocathode RF gun: Toward intensity-modulated radiation therapy (IMRT)

    International Nuclear Information System (INIS)

    In intensity-modulated radiation therapy (IMRT), the aim is to deliver reduced doses of radiation to normal tissue. As a step toward IMRT, we examined dynamic optical modulation of an electron beam produced by a photocathode RF gun. Images on photomasks were transferred onto a photocathode by relay imaging. The resulting beam was controlled by a remote mirror. The modulated electron beam maintained its shape on acceleration, had a fine spatial resolution, and could be moved dynamically by optical methods

  14. Dynamic optical modulation of an electron beam on a photocathode RF gun: Toward intensity-modulated radiation therapy (IMRT)

    Science.gov (United States)

    Kondoh, Takafumi; Kashima, Hiroaki; Yang, Jinfeng; Yoshida, Yoichi; Tagawa, Seiichi

    2008-10-01

    In intensity-modulated radiation therapy (IMRT), the aim is to deliver reduced doses of radiation to normal tissue. As a step toward IMRT, we examined dynamic optical modulation of an electron beam produced by a photocathode RF gun. Images on photomasks were transferred onto a photocathode by relay imaging. The resulting beam was controlled by a remote mirror. The modulated electron beam maintained its shape on acceleration, had a fine spatial resolution, and could be moved dynamically by optical methods.

  15. Dosimetry verification using radiochromic film for intensity- modulated radiation surgery

    International Nuclear Information System (INIS)

    A well known acceptance criteria for dose difference between calculated and measured dose distribution is 5%. But, when the technique of intensity modulated radiation is used in radiosurgery (IMRS) the high dose delivery imply to carry out a commissioning to verify these recommendations. This work proposes a methodology to verify the dose distributions in IMRS treatments using radiochromic film. The experimental methodology to measure the spatial dose distributions use radiochromic films GafChromic MD-55-2 previously calibrated in the same linear accelerator, for which it settled down a protocol in its handling and analysis according to the recommendations for film dosimetry. For that purpose an spherical phantom of 16 cm of diameter MAPM (meth-acrylate of poli-methyl or acrylic) was designed and constructed to simulate a head in whose interior it is possible to interchange pieces capable to simulate an injury and to place the films. According to the protocol suggested by the AAPM-TG55 all the films were cut to fit the phantom dimensions 24 hours before being irradiated and read it 48 hours later. The reading was performed using a commercial scanner (Agfa DuoScan T1200) in transmission mode. The films were digitized using 16 bits/pixel per channel in RGB mode color depth and 300 dpi. The analysis was performed using in-house software. In the analysis the isodoses curves that were measured experimentally and calculated by the system were compared, obtaining the discrepancies among them. The results showed that the best agreement between isodoses curves happens for the high doses (80% and 60%), whose deviations are in Table 1; for the low isodoses curves the discrepancies are greater, a possible answer of this difference is the sensitivity of the film that is of order of 3 Gy, comparable with the dose that is moderate in those curves, combined to it, this sensitivity depends on the scanner response. With the use of radiochromic films, GafChromic MD-55-2 implemented a

  16. Inverse planning optimization method for intensity modulated radiation therapy.

    Science.gov (United States)

    Lan, Yihua; Ren, Haozheng; Li, Cunhua; Min, Zhifang; Wan, Jinxin; Ma, Jianxin; Hung, Chih-Cheng

    2013-10-01

    In order to facilitate the leaf sequencing process in intensity modulated radiation therapy (IMRT), and design of a practical leaf sequencing algorithm, it is an important issue to smooth the planned fluence maps. The objective is to achieve both high-efficiency and high-precision dose delivering by considering characteristics of leaf sequencing process. The key factor which affects total number of monitor units for the leaf sequencing optimization process is the max flow value of the digraph which formulated from the fluence maps. Therefore, we believe that one strategy for compromising dose conformity and total number of monitor units in dose delivery is to balance the dose distribution function and the max flow value mentioned above. However, there are too many paths in the digraph, and we don't know the flow value of which path is the maximum. The maximum flow value among the horizontal paths was selected and used in the objective function of the fluence map optimization to formulate the model. The model is a traditional linear constrained quadratic optimization model which can be solved by interior point method easily. We believe that the smoothed maps from this model are more suitable for leaf sequencing optimization process than other smoothing models. A clinical head-neck case and a prostate case were tested and compared using our proposed model and the smoothing model which is based on the minimization of total variance. The optimization results with the same level of total number of monitor units (TNMU) show that the fluence maps obtained from our model have much better dose performance for the target/non-target region than the maps from total variance based on the smoothing model. This indicates that our model achieves better dose distribution when the algorithm suppresses the TNMU at the same level. Although we have just used the max flow value of the horizontal paths in the diagraph in the objective function, a good balance has been achieved between

  17. Survey of resident education in intensity-modulated radiation therapy.

    Science.gov (United States)

    Malik, Renuka; Oh, Julia L; Roeske, John C; Mundt, Arno J

    2005-06-01

    Intensity-modulated radiation therapy (IMRT) has been gaining increasing popularity among practicing physicians in the U.S., but the extent to which radiation oncology residents are taught the principles of this technology and are trained to use IMRT remains unknown. In this paper, we assessed the current level of resident education in IMRT in the United States. Chief residents at all 77 accredited radiation oncology programs were sent a 13-question survey addressing formal didactics and hands-on experience in IMRT. The survey assessed the frequency, subject, and format of IMRT didactics. Questions also addressed the number of IMRT patients and anatomical sites treated, resident involvement in the IMRT process, and the intent of IMRT use. Finally, residents were asked for their opinions on their IMRT education. Sixty-one surveys (79%) were completed. Overall, forty-three respondents (71%) reported receiving formal IMRT didactics, with nearly one-third reporting extensive didactics (> or = 3 lectures/seminars et cetera per year). The most common didactic formats were lectures (95%) and journal clubs (63%), most commonly supervised by physicists (98%). Involvement by physicians and radiobiologists were reported by 63% and 7% of respondents, respectively. Overall, 87% of respondents had hands-on IMRT training, with nearly one-half having treated > 25 patients. The most common sites treated were head and neck (94%) and prostate (81%). Involvement in all aspects of the IMRT process was common, particularly target and tissue delineation (98%) and plan evaluation (93%). Most respondents (79%) with hands-on experience reported receiving formal didactics. However, nearly one-third received no or only minimal formal didactics. The percentage of respondents desiring increased IMRT didactics and hands-on experience were 70% and 47%, respectively. Our results suggest that the great majority of radiation oncology residents in the United States are currently exposed to didactics

  18. Pleural Intensity-Modulated Radiotherapy for Malignant Pleural Mesothelioma

    Energy Technology Data Exchange (ETDEWEB)

    Rosenzweig, Kenneth E., E-mail: ken.rosenzweig@mountsinai.org [Department of Radiation Oncology, Mount Sinai Medical Center, New York, NY (United States); Zauderer, Marjorie G. [Department of Medicine, Thoracic Oncology Service, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Laser, Benjamin [Department of Radiation Oncology, Henry Ford Hospital, Detroit, MI (United States); Krug, Lee M. [Department of Medicine, Thoracic Oncology Service, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Yorke, Ellen [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Sima, Camelia S. [Department of Epidemiology/Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Rimner, Andreas [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Flores, Raja [Department of Surgery, Mount Sinai Medical Center, New York, NY (United States); Rusch, Valerie [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

    2012-07-15

    Purpose: In patients with malignant pleural mesothelioma who are unable to undergo pneumonectomy, it is difficult to deliver tumoricidal radiation doses to the pleura without significant toxicity. We have implemented a technique of using intensity-modulated radiotherapy (IMRT) to treat these patients, and we report the feasibility and toxicity of this approach. Methods and Materials: Between 2005 and 2010, 36 patients with malignant pleural mesothelioma and two intact lungs (i.e., no previous pneumonectomy) were treated with pleural IMRT to the hemithorax (median dose, 46.8 Gy; range, 41.4-50.4) at Memorial Sloan-Kettering Cancer Center. Results: Of the 36 patients, 56% had right-sided tumors. The histologic type was epithelial in 78%, sarcomatoid in 6%, and mixed in 17%, and 6% had Stage I, 28% had Stage II, 33% had Stage III, and 33% had Stage IV. Thirty-two patients (89%) received induction chemotherapy (mostly cisplatin and pemetrexed); 56% underwent pleurectomy/decortication before IMRT and 44% did not undergo resection. Of the 36 patients evaluable for acute toxicity, 7 (20%) had Grade 3 or worse pneumonitis (including 1 death) and 2 had Grade 3 fatigue. In 30 patients assessable for late toxicity, 5 had continuing Grade 3 pneumonitis. For patients treated with surgery, the 1- and 2-year survival rate was 75% and 53%, and the median survival was 26 months. For patients who did not undergo surgical resection, the 1- and 2-year survival rate was 69% and 28%, and the median survival was 17 months. Conclusions: Treating the intact lung with pleural IMRT in patients with malignant pleural mesothelioma is a safe and feasible treatment option with an acceptable rate of pneumonitis. Additionally, the survival rates were encouraging in our retrospective series, particularly for the patients who underwent pleurectomy/decortication. We have initiated a Phase II trial of induction chemotherapy with pemetrexed and cisplatin with or without pleurectomy

  19. Pleural Intensity-Modulated Radiotherapy for Malignant Pleural Mesothelioma

    International Nuclear Information System (INIS)

    Purpose: In patients with malignant pleural mesothelioma who are unable to undergo pneumonectomy, it is difficult to deliver tumoricidal radiation doses to the pleura without significant toxicity. We have implemented a technique of using intensity-modulated radiotherapy (IMRT) to treat these patients, and we report the feasibility and toxicity of this approach. Methods and Materials: Between 2005 and 2010, 36 patients with malignant pleural mesothelioma and two intact lungs (i.e., no previous pneumonectomy) were treated with pleural IMRT to the hemithorax (median dose, 46.8 Gy; range, 41.4–50.4) at Memorial Sloan-Kettering Cancer Center. Results: Of the 36 patients, 56% had right-sided tumors. The histologic type was epithelial in 78%, sarcomatoid in 6%, and mixed in 17%, and 6% had Stage I, 28% had Stage II, 33% had Stage III, and 33% had Stage IV. Thirty-two patients (89%) received induction chemotherapy (mostly cisplatin and pemetrexed); 56% underwent pleurectomy/decortication before IMRT and 44% did not undergo resection. Of the 36 patients evaluable for acute toxicity, 7 (20%) had Grade 3 or worse pneumonitis (including 1 death) and 2 had Grade 3 fatigue. In 30 patients assessable for late toxicity, 5 had continuing Grade 3 pneumonitis. For patients treated with surgery, the 1- and 2-year survival rate was 75% and 53%, and the median survival was 26 months. For patients who did not undergo surgical resection, the 1- and 2-year survival rate was 69% and 28%, and the median survival was 17 months. Conclusions: Treating the intact lung with pleural IMRT in patients with malignant pleural mesothelioma is a safe and feasible treatment option with an acceptable rate of pneumonitis. Additionally, the survival rates were encouraging in our retrospective series, particularly for the patients who underwent pleurectomy/decortication. We have initiated a Phase II trial of induction chemotherapy with pemetrexed and cisplatin with or without pleurectomy

  20. Comparative study of conformal versus intensity modulated radiotherapy treatment plans

    International Nuclear Information System (INIS)

    Full text: In order to establish some early clinical experience in the use of intensity modulated radiotherapy (IMRT) as an alternative treatment method to conformal irradiation, we selected a number of specifically difficult clinical cases to compare. Complex tumour shapes located in the skull (two cases), close to the spinal cord (two cases) and one standard prostate case were chosen for this study. A Varian CadPlan system is used for the conformal treatment plans and Helios for the IMRT plans. In both these techniques, the linear accelerator multileaf collimator system is used to shape the beam about the target volume. The Royal North Shore Hospital Varian Clinac 600C/D linear accelerator also has dynamic multileaf collimator control (DMLC) capabilities for IMRT. The five cases reported here were planned by the radiation therapists for conformal treatment and then re-planned by physics using the CadPlan's Helios inverse planning option to produce an alternative IMRT plan. Both planners worked independently of each other. Treatment set-up errors were not considered as part of this study but it is apparent here that positional errors and immobilisation are particularly important factors to consider. An allowance for all errors must therefore be included for all critical organ outlines as well as the target volume for both the conformal or IMRT treatments. Visually, the covering of regularly shaped treatment volumes for the IMRT plans was improved marginally over the conformal plan. However, complex treatment volumes (such as the posterior orbital region with surrounding critical structures) showed very clear improvements. The IMRT dose drop-off at the edge of the target volume was not as sharp as the conformal equivalent. The dose-volume-histogram (DVH) provides a limited analytical tool to quantify these observations. The DVH generally indicated similar curves for the IMRT and conformal target volume but significant IMRT improvements in limiting the dose to

  1. SmartArc-Based Volumetric Modulated Arc Therapy for Oropharyngeal Cancer: A Dosimetric Comparison With Both Intensity-Modulated Radiation Therapy and Helical Tomotherapy

    International Nuclear Information System (INIS)

    Purpose: To investigate the roles of volumetric modulated arc therapy with SmartArc (VMAT-S), intensity-modulated radiation therapy (IMRT), and helical tomotherapy (HT) for oropharyngeal cancer using a simultaneous integrated boost (SIB) approach. Methods and Materials: Eight patients treated with IMRT were selected at random. Plans were computed for both IMRT and VMAT-S (using Pinnacle TPS for an Elekta Infinity linac) along with HT. A three-dose level prescription was used to deliver 70 Gy, 63 Gy, and 58.1 Gy to regions of macroscopic, microscopic high-risk, and microscopic low-risk disease, respectively. All doses were given in 35 fractions. Comparisons were performed on dose-volume histogram data, monitor units per fraction (MU/fx), and delivery time. Results: VMAT-S target coverage was close to that achieved by IMRT, but inferior to HT. The conformity and homogeneity within the PTV were improved for HT over all strategies. Sparing of the organs at risk (OAR) was achieved with all modalities. VMAT-S (along with HT) shortened delivery time (mean, -38%) and reduced MU/fx (mean, -28%) compared with IMRT. Conclusion: VMAT-S represents an attractive solution because of the shorter delivery time and the lower number of MU/fx compared with IMRT. However, in this complex clinical setting, current VMAT-S does not appear to provide any distinct advantage compared with helical tomotherapy.

  2. Analysis of small-signal intensity modulation of semiconductor lasers taking account of gain suppression

    Indian Academy of Sciences (India)

    Moustafa Ahmed; Ali El-Lafi

    2008-07-01

    This paper demonstrates theoretical characterization of intensity modulation of semiconductor lasers (SL’s). The study is based on a small-signal model to solve the laser rate equations taking into account suppression of optical gain. Analytical forms of the small-signal modulation response and modulation bandwidth are derived. Influences of the bias current, modulation index and modulation frequency as well as gain suppression on modulation characteristics are examined. Computer simulation of the model is applied to 1.55-m InGaAsP lasers. The results show that when the SL is biased far-above threshold, the increase of gain suppression increases both the modulation response and its peak frequency. The modulation bandwidth also increases but the laser damping rate decreases. Quantitative description of the relationships of both modulation bandwidth vs. relaxation frequency and maximum modulation bandwidth vs. nonlinear gain coefficient are presented.

  3. Five-year Results of Whole Breast Intensity Modulated Radiation Therapy for the Treatment of Early Stage Breast Cancer: The Fox Chase Cancer Center Experience

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Lanea M.M., E-mail: Lanea.Keller@fccc.edu [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Sopka, Dennis M. [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Li Tianyu [Department of Biostatistics, Fox Chase Cancer Center, Philadelphia, PA (United States); Klayton, Tracy; Li Jinsheng; Anderson, Penny R. [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Bleicher, Richard J.; Sigurdson, Elin R. [Department of Surgical Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Freedman, Gary M. [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA (United States)

    2012-11-15

    Purpose: To report the 5-year outcomes using whole-breast intensity-modulated radiation therapy (IMRT) for the treatment of early-stage-breast cancer at the Fox Chase Cancer Center. Methods and Materials: A total of 946 women with early-stage breast cancer (stage 0, I, or II) were treated with IMRT after surgery with or without systemic therapy from 2003-2010. Whole-breast radiation was delivered via an IMRT technique with a median whole-breast radiation dose of 46 Gy and median tumor bed boost of 14 Gy. Endpoints included local-regional recurrence, cosmesis, and late complications. Results: With a median follow-up of 31 months (range, 1-97 months), there were 12 ipsilateral breast tumor recurrences (IBTR) and one locoregional recurrence. The 5-year actuarial IBTR and locoregional recurrence rates were 2.0% and 2.4%. Physician-reported cosmestic outcomes were available for 645 patients: 63% were considered 'excellent', 33% 'good', and <1.5% 'fair/poor'. For physician-reported cosmesis, boost doses {>=}16 Gy, breast size >900 cc, or boost volumes >34 cc were significantly associated with a 'fair/poor' cosmetic outcome. Fibrosis, edema, erythema, and telangectasia were also associated with 'fair/poor' physician-reported cosmesis; erythema and telangectasia remained significant on multivariate analysis. Patient-reported cosmesis was available for 548 patients, and 33%, 50%, and 17% of patients reported 'excellent', 'good', and 'fair/poor' cosmesis, respectively. The use of a boost and increased boost volume: breast volume ratio were significantly associated with 'fair/poor' outcomes. No parameter for patient-reported cosmesis was significant on multivariate analysis. The chances of experiencing a treatment related effect was significantly associated with a boost dose {>=}16 Gy, receipt of chemotherapy and endocrine therapy, large breast size, and electron boost energy

  4. Comparative analysis of 60Co intensity-modulated radiation therapy

    Science.gov (United States)

    Fox, Christopher; Romeijn, H. Edwin; Lynch, Bart; Men, Chunhua; Aleman, Dionne M.; Dempsey, James F.

    2008-06-01

    In this study, we perform a scientific comparative analysis of using 60Co beams in intensity-modulated radiation therapy (IMRT). In particular, we evaluate the treatment plan quality obtained with (i) 6 MV, 18 MV and 60Co IMRT; (ii) different numbers of static multileaf collimator (MLC) delivered 60Co beams and (iii) a helical tomotherapy 60Co beam geometry. We employ a convex fluence map optimization (FMO) model, which allows for the comparison of plan quality between different beam energies and configurations for a given case. A total of 25 clinical patient cases that each contain volumetric CT studies, primary and secondary delineated targets, and contoured structures were studied: 5 head-and-neck (H&N), 5 prostate, 5 central nervous system (CNS), 5 breast and 5 lung cases. The DICOM plan data were anonymized and exported to the University of Florida optimized radiation therapy (UFORT) treatment planning system. The FMO problem was solved for each case for 5-71 equidistant beams as well as a helical geometry for H&N, prostate, CNS and lung cases, and for 3-7 equidistant beams in the upper hemisphere for breast cases, all with 6 MV, 18 MV and 60Co dose models. In all cases, 95% of the target volumes received at least the prescribed dose with clinical sparing criteria for critical organs being met for all structures that were not wholly or partially contained within the target volume. Improvements in critical organ sparing were found with an increasing number of equidistant 60Co beams, yet were marginal above 9 beams for H&N, prostate, CNS and lung. Breast cases produced similar plans for 3-7 beams. A helical 60Co beam geometry achieved similar plan quality as static plans with 11 equidistant 60Co beams. Furthermore, 18 MV plans were initially found not to provide the same target coverage as 6 MV and 60Co plans; however, adjusting the trade-offs in the optimization model allowed equivalent target coverage for 18 MV. For plans with comparable target coverage

  5. Intensity modulated radiotherapy versus volumetric modulated arc therapy in breast cancer: A comparative dosimetric analysis

    Directory of Open Access Journals (Sweden)

    KR Muralidhar

    2015-01-01

    Full Text Available Purpose: Intensity modulated radiotherapy (IMRT and volumetric modulated arc therapy (VMAT has the capacity to optimize the dose distribution. We analyzed the dosimetric differences of plans in treatment planning system (TPS between VMAT and IMRT in treating breast cancer. Methods: Fourteen patients were simulated, planned, and treated with VMAT using single, double or partial arcs. IMRT treatments were generated using 4 to 5 tangential IMRT fields for the same patients. All treatment plans were planned for 50 Gy in 25 fractions. The VMAT and IMRT plans were compared using the planning target volume (PTV dose and doses to the other organs at risk (OARs. Results: For the PTV, comparable minimum, mean, maximum, median, and modal dose as well equivalent sphere diameter of the structure (Equis were observed between VMAT and IMRT plans and found that these values were significantly equal in both techniques. The right lung mean and modal doses were considerably higher in VMAT plans while maximum value was considerably lower when compared with IMRT plans. The left lung mean and modal doses were higher with VMAT while maximum doses were higher in IMRT plans. The mean dose to the heart and maximum dose to the spinal cord was lower with IMRT. The mean dose to the body was higher in VMAT plans while the maximum dose was higher in IMRT plans. Conclusion: Four field tangential IMRT delivered comparable PTV dose with generally less dose to normal tissues in our breast cancer treatment study. The IMRT plans typically had more favourable dose characteristics to the lung, heart, and spinal cord and body dose when compared with VMAT. The only minor advantage of VMAT for breast cases was slightly better PTV coverage.

  6. A boost for KAON

    International Nuclear Information System (INIS)

    Earlier this year, a report by a specially-formed subcommittee of the US Nuclear Science Advisory Committee gave an important boost to the proposal to build a high intensity particle beam 'factory' at the Canadian TRIUMF laboratory in Vancouver. (orig./HSI).

  7. Equatorial noise emissions with quasiperiodic modulation of wave intensity

    Czech Academy of Sciences Publication Activity Database

    Němec, F.; Santolík, Ondřej; Hrbáčková, Zuzana; Pickett, J. S.; Cornilleau-Wehrlin, N.

    2015-01-01

    Roč. 120, č. 4 (2015), s. 2649-2661. ISSN 2169-9380 R&D Projects: GA MŠk(CZ) LH11122 Institutional support: RVO:68378289 Keywords : equatorial noise * magnetosonic waves * quasiperiodic modulation Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.440, year: 2013 http://onlinelibrary.wiley.com/doi/10.1002/2014JA020816/full

  8. Numerical Extraction of Distributions of Space-charge and Polarization from Laser Intensity Modulation Method

    OpenAIRE

    Tuncer, Enis; Lang, Sidney.B.

    2004-01-01

    The Fredholm integral equation of the laser intensity modulation method is solved with the application of the Monte Carlo technique and a least-squares solver. The numerical procedure is tested on simulated data.

  9. Intensity-modulated linear-frequency-modulated continuous-wave lidar for distributed media: fundamentals of technique

    OpenAIRE

    Batet Torrell, Óscar; Dios Otín, Víctor Federico; Comerón Tejero, Adolfo; Agishev, Ravil R.

    2010-01-01

    We analyze the intensity-modulation frequency-modulated continuous-wave (FMCW) technique for lidar remote sensing in the context of its application to distributed media. The goal of the technique is the reproduction of the sounded-medium profile along the emission path. A conceptual analysis is carried out to show the problems the basic version of the method presents for this application. The principal point is the appearance of a bandpass filtering effect, which seems to hinder its use in...

  10. Cardiac Exposure in the Dynamic Conformal Arc Therapy, Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy of Lung Cancer

    OpenAIRE

    Xin Ming; Yuanming Feng; Huan Liu; Ying Zhang; Li Zhou; Jun Deng

    2015-01-01

    Purpose To retrospectively evaluate the cardiac exposure in three cohorts of lung cancer patients treated with dynamic conformal arc therapy (DCAT), intensity-modulated radiotherapy (IMRT), or volumetric modulated arc therapy (VMAT) at our institution in the past seven years. Methods and Materials A total of 140 lung cancer patients were included in this institutional review board approved study: 25 treated with DCAT, 70 with IMRT and 45 with VMAT. All plans were generated in a same commercia...

  11. Intensity-modulated radiotherapy and volumetric-modulated arc therapy for malignant pleural mesothelioma after extrapleural pleuropneumonectomy

    OpenAIRE

    Krayenbuehl, J; Riesterer, O; Graydon, S; Dimmerling, P; Kloeck, S; Ciernik, I F

    2013-01-01

    Radiotherapy reduces the local relapse rate after pleuropneumonectomy of malignant pleural mesothelioma (MPM). The optimal treatment technique with photons remains undefined. Comparative planning for intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) was performed. Six MPM patients with significant postoperative intrathoracic air cavities were planned with IMRT and VMAT. A dose comparison for the targets and organ at risks (OAR) was performed. Robustness was a...

  12. Whole Abdominopelvic Intensity-Modulated Radiation Therapy for Desmoplastic Small Round Cell Tumor After Surgery

    International Nuclear Information System (INIS)

    Purpose: Desmoplastic small round cell tumor (DSCRT) is an uncommon pediatric tumor with a poor prognosis. Aggressive multimodality therapy is the current treatment approach; however. treatment toxicity is of concern. We report our results with whole abdominopelvic intensity-modulated radiation therapy (WAP-IMRT) as a component of multimodality therapy for DSCRT at a single institution. Materials/Methods: Medical records of all patients with DSCRT who received WAP-IMRT as part of definitive treatment at MD Anderson (2006–2010) were identified and reviewed. Results: Eight patients with DSRCT received WAP-IMRT with a median follow-up of 15.2 months. All patients received multiple courses of chemotherapy followed by surgical debulking of intra-abdominal disease; seven also had intraoperative hyperthermic cisplatin. WAP-IMRT was delivered to a total dose of 30 Gy postoperatively; four patients received a simultaneous boost (6–10 Gy) to sites of gross residual disease. Seven patients received concurrent chemotherapy during WAP-IMRT. No Radiation Therapy Oncology Group Grade 4 nausea, vomiting, or diarrhea occurred during RT. Red-cell transfusions were given to two patients to maintain hemoglobin levels >10 g/dL. Grade 4 cytopenia requiring growth factor support occurred in only one patient; no other significant cytopenias were noted. WAP-IMRT resulted in 25% lower radiation doses to the lumbosacral vertebral bodies and pelvic bones than conventional RT plans. The median time to local or distant failure after WAP-IMRT was 8.73 months in seven patients. One patient who had completed RT 20 months before the last follow-up remains alive without evidence of disease. Five patients (63%) experienced treatment failure in the abdomen. Distant failure occurred in three patients (37.5%). Conclusions: WAP-IMRT with concurrent radiosensitizing chemotherapy was well tolerated after aggressive surgery for DSCRT. Enhanced bone sparing with IMRT probably accounts for the low

  13. Whole Abdominopelvic Intensity-Modulated Radiation Therapy for Desmoplastic Small Round Cell Tumor After Surgery

    Energy Technology Data Exchange (ETDEWEB)

    Pinnix, Chelsea C.; Fontanilla, Hiral P. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Hayes-Jordan, Andrea [Department of Pediatric Surgical Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Subbiah, Vivek [Department of Pediatrics, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Bilton, Stephen D.; Chang, Eric L.; Grosshans, David R.; McAleer, Mary F.; Sulman, Eric P.; Woo, Shiao Y. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Anderson, Peter [Department of Pediatrics, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Green, Holly L. [Department of Pediatric Surgical Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Mahajan, Anita, E-mail: amahajan@mdanderson.org [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States)

    2012-05-01

    Purpose: Desmoplastic small round cell tumor (DSCRT) is an uncommon pediatric tumor with a poor prognosis. Aggressive multimodality therapy is the current treatment approach; however. treatment toxicity is of concern. We report our results with whole abdominopelvic intensity-modulated radiation therapy (WAP-IMRT) as a component of multimodality therapy for DSCRT at a single institution. Materials/Methods: Medical records of all patients with DSCRT who received WAP-IMRT as part of definitive treatment at MD Anderson (2006-2010) were identified and reviewed. Results: Eight patients with DSRCT received WAP-IMRT with a median follow-up of 15.2 months. All patients received multiple courses of chemotherapy followed by surgical debulking of intra-abdominal disease; seven also had intraoperative hyperthermic cisplatin. WAP-IMRT was delivered to a total dose of 30 Gy postoperatively; four patients received a simultaneous boost (6-10 Gy) to sites of gross residual disease. Seven patients received concurrent chemotherapy during WAP-IMRT. No Radiation Therapy Oncology Group Grade 4 nausea, vomiting, or diarrhea occurred during RT. Red-cell transfusions were given to two patients to maintain hemoglobin levels >10 g/dL. Grade 4 cytopenia requiring growth factor support occurred in only one patient; no other significant cytopenias were noted. WAP-IMRT resulted in 25% lower radiation doses to the lumbosacral vertebral bodies and pelvic bones than conventional RT plans. The median time to local or distant failure after WAP-IMRT was 8.73 months in seven patients. One patient who had completed RT 20 months before the last follow-up remains alive without evidence of disease. Five patients (63%) experienced treatment failure in the abdomen. Distant failure occurred in three patients (37.5%). Conclusions: WAP-IMRT with concurrent radiosensitizing chemotherapy was well tolerated after aggressive surgery for DSCRT. Enhanced bone sparing with IMRT probably accounts for the low hematologic

  14. Device to color modulate a stationary light beam gives high intensity

    Science.gov (United States)

    Gantz, W. A.

    1966-01-01

    Signal controlled system color modulates a beam of light while also providing high intensity and a stationary beam, either collimated or focused. The color modulation acquired by the presented system can be compatible with any color film by employing color filters formed to provide a color wedge having a color distribution compatible with the films color sensitivity.

  15. Modulation of ionization on laser frequency in ultra-short pulse intense laser-gas-target

    Institute of Scientific and Technical Information of China (English)

    Hu Qiang-Lin; Liu Shi-Bing

    2006-01-01

    Based on the dispersion relation of intense laser pulse propagating in gradually ionized plasma, this paper discusses the frequency modulation induced by ionization of an ultra-short intense laser pulse interacting with a gas target.The relationship between the frequency modulation and the ionization rate, the plasmas frequency variation, and the polarization of atoms (ions) is analysed. The numerical results indicate that, at high frequency, the polarization of atoms (ions) plays a more important role than plasma frequency variation in modulating the laser frequency, and the laser frequency variation is different at different positions of the laser pulse.

  16. Five-year Results of Whole Breast Intensity Modulated Radiation Therapy for the Treatment of Early Stage Breast Cancer: The Fox Chase Cancer Center Experience

    International Nuclear Information System (INIS)

    Purpose: To report the 5-year outcomes using whole-breast intensity-modulated radiation therapy (IMRT) for the treatment of early-stage-breast cancer at the Fox Chase Cancer Center. Methods and Materials: A total of 946 women with early-stage breast cancer (stage 0, I, or II) were treated with IMRT after surgery with or without systemic therapy from 2003-2010. Whole-breast radiation was delivered via an IMRT technique with a median whole-breast radiation dose of 46 Gy and median tumor bed boost of 14 Gy. Endpoints included local-regional recurrence, cosmesis, and late complications. Results: With a median follow-up of 31 months (range, 1-97 months), there were 12 ipsilateral breast tumor recurrences (IBTR) and one locoregional recurrence. The 5-year actuarial IBTR and locoregional recurrence rates were 2.0% and 2.4%. Physician-reported cosmestic outcomes were available for 645 patients: 63% were considered “excellent”, 33% “good”, and 900 cc, or boost volumes >34 cc were significantly associated with a “fair/poor” cosmetic outcome. Fibrosis, edema, erythema, and telangectasia were also associated with “fair/poor” physician-reported cosmesis; erythema and telangectasia remained significant on multivariate analysis. Patient-reported cosmesis was available for 548 patients, and 33%, 50%, and 17% of patients reported “excellent”, “good”, and “fair/poor” cosmesis, respectively. The use of a boost and increased boost volume: breast volume ratio were significantly associated with “fair/poor” outcomes. No parameter for patient-reported cosmesis was significant on multivariate analysis. The chances of experiencing a treatment related effect was significantly associated with a boost dose ≥16 Gy, receipt of chemotherapy and endocrine therapy, large breast size, and electron boost energy. Conclusions: Whole-breast IMRT is associated with very low rates of local recurrence at 5 years, 83%-98% “good/excellent” cosmetic outcomes, and minimal

  17. Modulational instability of ultra-intense linearly polarized laser pulse in electron–positron plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Qiang-Lin, E-mail: qlhu@jgsu.edu.cn [Department of Physics, Jinggangshan University, Ji' an, Jiangxi 343009 (China); Xiao, Gui-Lan [Library, Jinggangshan University, Ji' an, Jiangxi 343009 (China); Yu, Xiao-Guang [Department of Physics, Jinggangshan University, Ji' an, Jiangxi 343009 (China); Wang, Zhi-Guo [Department of Physics, Tongji University, Shanghai 200092 (China); Luo, Xiao-Bing [Department of Physics, Jinggangshan University, Ji' an, Jiangxi 343009 (China)

    2013-11-15

    Based on the wave equation of ultra-intense linearly polarized laser pulse propagating in electron–positron plasmas, the modulational instability is investigated. The nonlinear dispersion relation and the growth rate of instability are derived. The effects of plasmas number density, temperature, and laser intensity on the growth rate are analyzed. Results show that in an electron–positron plasma with certain background density, the intensity of the modulation instability is mainly determined by the competition between the nonlinearity in the interaction and the relativistic light ponderomotive driven density responses.

  18. Intensity modulation and direct detection quantum key distribution based on quantum noise

    Science.gov (United States)

    Ikuta, Takuya; Inoue, Kyo

    2016-01-01

    Quantum key distribution (QKD) has been studied for achieving perfectly secure cryptography based on quantum mechanics. This paper presents a novel QKD scheme that is based on an intensity-modulation and direct-detection system. Two slightly intensity-modulated pulses are sent from a transmitter, and a receiver determines key bits from the directly detected intensity. We analyzed the system performance for two typical eavesdropping methods, a beam splitting attack and an intercept-resend attack, with an assumption that the transmitting and receiving devices are fully trusted. Our brief analysis showed that short- or middle-range QKD systems are achievable with a simple setup.

  19. Phase-amplitude crosstalk in intensity modulated near infrared spectroscopy

    Science.gov (United States)

    Alford, K.; Wickramasinghe, Y.

    2000-05-01

    Near infrared spectroscopy (NIRS) instruments that rely on phase sensitive detection suffer from what is called "phase-amplitude crosstalk," i.e., the phase measured is dependent on the average light intensity entering the detector. Changes in detector rise time with input light intensity is the accepted explanation of this phenomenon. It is concluded here that an additional simple mechanism can cause phase-amplitude errors, particularly if the ratio of the ac component of the detected signal to the dc component is low. It is shown that the form of the phase distortion encountered during the development of a new phase sensitive NIR instrument can be modeled by assuming the presence of a synchronous interfering signal, due to rf coupling, at the detector output. This modeling allows a required margin between the detected signal of interest, i.e., the signal from the tissue and the interfering signal to be set in order to achieve a measured phase accuracy necessary to derive sufficiently accurate clinical parameters.

  20. Chorus intensity modulation driven by time-varying field-aligned low-energy plasma

    Science.gov (United States)

    Nishimura, Y.; Bortnik, J.; Li, W.; Liang, J.; Thorne, R. M.; Angelopoulos, V.; Le Contel, O.; Auster, U.; Bonnell, J. W.

    2015-09-01

    Recent studies have shown that chorus waves are responsible for scattering and precipitating the energetic electrons that drive the pulsating aurora. While some of the chorus intensity modulation events are correlated with <~100 eV electron density modulation, most of the chorus intensity modulation events in the postmidnight sector occur without apparent density changes. Although it is generally difficult to measure evolution of low-energy (<~20 eV) electron fluxes due to constraints imposed by the spacecraft potential and electrostatic analyzer (ESA) energy range limit, we identified using Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite data that low-energy ions of ~100 eV show density modulation that is correlated with chorus intensity modulation. Those low-energy ions and electrons are field-aligned with major peaks in 0° (for northern hemisphere winter event) and 180° (for northern hemisphere summer event) pitch angle, indicating that outflowing plasma from the sunlit hemisphere is the source of the low-energy plasma density modulation near the equator. Plasma sheet plasma density, and ambient electric and magnetic fields do not show modulations that are correlated with the chorus intensity modulation. Assuming charge neutrality, the low-energy ions can be used to represent cold plasma density in wave growth rate calculations, and the enhancements of the low-energy plasma density are found to contribute most effectively to chorus linear growth rates. These results suggest that chorus intensity modulation is driven by a feedback process where outflowing plasma due to energetic electron precipitation increases the equatorial density that drives further electron precipitation.

  1. Switching circuit to improve the frequency modulation difference-intensity THz quantum cascade laser imaging

    Energy Technology Data Exchange (ETDEWEB)

    Saat, N. K. [Department of Physics, Faculty of Science, University Putra Malaysia (Malaysia); Dean, P.; Khanna, S. P.; Salih, M.; Linfield, E. H.; Davies, A. G. [School of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom)

    2015-04-24

    We demonstrate new switching circuit for difference-intensity THz quantum cascade laser (QCL) imaging by amplitude modulation and lock in detection. The switching circuit is designed to improve the frequency modulation so that it can stably lock the amplitude modulation of the QCL and the detector output. The combination of a voltage divider and a buffer in switching circuit to quickly switch the amplitude of the QCL biases of 15.8 V and 17.2 V is successfully to increase the frequency modulation up to ∼100 Hz.

  2. Switching circuit to improve the frequency modulation difference-intensity THz quantum cascade laser imaging

    International Nuclear Information System (INIS)

    We demonstrate new switching circuit for difference-intensity THz quantum cascade laser (QCL) imaging by amplitude modulation and lock in detection. The switching circuit is designed to improve the frequency modulation so that it can stably lock the amplitude modulation of the QCL and the detector output. The combination of a voltage divider and a buffer in switching circuit to quickly switch the amplitude of the QCL biases of 15.8 V and 17.2 V is successfully to increase the frequency modulation up to ∼100 Hz

  3. Boosting high-intensity focused ultrasound-induced anti-tumor immunity using a sparse-scan strategy that can more effectively promote dendritic cell maturation

    Directory of Open Access Journals (Sweden)

    Zhong Pei

    2010-01-01

    Full Text Available Abstract Background The conventional treatment protocol in high-intensity focused ultrasound (HIFU therapy utilizes a dense-scan strategy to produce closely packed thermal lesions aiming at eradicating as much tumor mass as possible. However, this strategy is not most effective in terms of inducing a systemic anti-tumor immunity so that it cannot provide efficient micro-metastatic control and long-term tumor resistance. We have previously provided evidence that HIFU may enhance systemic anti-tumor immunity by in situ activation of dendritic cells (DCs inside HIFU-treated tumor tissue. The present study was conducted to test the feasibility of a sparse-scan strategy to boost HIFU-induced anti-tumor immune response by more effectively promoting DC maturation. Methods An experimental HIFU system was set up to perform tumor ablation experiments in subcutaneous implanted MC-38 and B16 tumor with dense- or sparse-scan strategy to produce closely-packed or separated thermal lesions. DCs infiltration into HIFU-treated tumor tissues was detected by immunohistochemistry and flow cytometry. DCs maturation was evaluated by IL-12/IL-10 production and CD80/CD86 expression after co-culture with tumor cells treated with different HIFU. HIFU-induced anti-tumor immune response was evaluated by detecting growth-retarding effects on distant re-challenged tumor and tumor-specific IFN-γ-secreting cells in HIFU-treated mice. Results HIFU exposure raised temperature up to 80 degrees centigrade at beam focus within 4 s in experimental tumors and led to formation of a well-defined thermal lesion. The infiltrated DCs were recruited to the periphery of lesion, where the peak temperature was only 55 degrees centigrade during HIFU exposure. Tumor cells heated to 55 degrees centigrade in 4-s HIFU exposure were more effective to stimulate co-cultured DCs to mature. Sparse-scan HIFU, which can reserve 55 degrees-heated tumor cells surrounding the separated lesions, elicited an

  4. Long-term results of forward intensity-modulated radiation therapy for patients with early-stage breast cancer

    International Nuclear Information System (INIS)

    To observe long-term clinical outcomes for patients with early-stage breast cancer treated with forward intensity-modulated radiation therapy (IMRT), including local control and clinical toxicities. We retrospectively analyzed a total of 214 patients with stage I-II breast cancer who were treated with breast conserving surgery followed by adjuvant breast radiation therapy between 2001 and 2008. All patients were treated using forward IMRT. The whole breast was irradiated to a dose of 50 to 50.4 Gy followed by an 8 to 12 Gy electron boost to the surgical bed. The median age was 46 years (range, 21 to 82 years) and the medial follow-up time was 7.3 years (range, 2.4 to 11.7 years). Stage T1 was 139 (65%) and T2 was 75 (35%), respectively. Ipsilateral breast recurrence was observed in 3 patients. The 5- and 10-year local control rates were 99.1% and 97.8%, respectively. The cosmetic outcome was evaluated according to the Harvard scale and 89.4% of patients were scored as excellent or good. The whole breast radiation therapy as an adjuvant treatment using a forward IMRT technique showed excellent long-term local control as well as favorable outcomes of toxicity and cosmesis.

  5. Long-term results of forward intensity-modulated radiation therapy for patients with early-stage breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Boram; Suh, Hyun Suk; Lee, Ji Hae; Lee, Kyung Ja; Lee, Rena; Moon, Byung In [Ewha Womans University College of Medicine, Seoul (Korea, Republic of)

    2013-12-15

    To observe long-term clinical outcomes for patients with early-stage breast cancer treated with forward intensity-modulated radiation therapy (IMRT), including local control and clinical toxicities. We retrospectively analyzed a total of 214 patients with stage I-II breast cancer who were treated with breast conserving surgery followed by adjuvant breast radiation therapy between 2001 and 2008. All patients were treated using forward IMRT. The whole breast was irradiated to a dose of 50 to 50.4 Gy followed by an 8 to 12 Gy electron boost to the surgical bed. The median age was 46 years (range, 21 to 82 years) and the medial follow-up time was 7.3 years (range, 2.4 to 11.7 years). Stage T1 was 139 (65%) and T2 was 75 (35%), respectively. Ipsilateral breast recurrence was observed in 3 patients. The 5- and 10-year local control rates were 99.1% and 97.8%, respectively. The cosmetic outcome was evaluated according to the Harvard scale and 89.4% of patients were scored as excellent or good. The whole breast radiation therapy as an adjuvant treatment using a forward IMRT technique showed excellent long-term local control as well as favorable outcomes of toxicity and cosmesis.

  6. Modern optical signal processing experiments demonstrating intensity and pulse-width modulation using an acousto-optic modulator

    Science.gov (United States)

    Poon, Ting-Chung; McNeill, Mark D.; Moore, Daniel J.

    1997-09-01

    Two experiments are presented to introduce undergraduate students in electrical engineering or physics to modern optical signal processing. Both experiments use an acousto-optic (AO) Bragg cell together with additional electronics to modify the intensity of a laser beam. Specifically, we show how an AO feedback system operating in the Bragg regime can be configured to produce amplitude modulated (AM) and pulse-width modulated optical signals. The basic components of the AO feedback system include a laser, an AO Bragg cell, an electronic AM modulator, a photodetector, an amplifier, and an electronic adder. Except for the laser, the AM modulator, and the Bragg cell, each of these components can be constructed with low cost electronics. A tutorial outlining the principles of acousto-optics is included to provide sufficient understanding of the Bragg cell. The project described in the paper has been used as a demonstration for junior- and senior-level undergraduate students in electrical engineering communications and optics classes.

  7. Assessing the feasibility of volumetric-modulated arc therapy using simultaneous integrated boost (SIB-VMAT): An analysis for complex head-neck, high-risk prostate and rectal cancer cases

    International Nuclear Information System (INIS)

    Intensity-modulated radiotherapy (IMRT) allowed the simultaneous delivery of different doses to different target volumes within a single fraction, an approach called simultaneous integrated boost (SIB). As consequence, the fraction dose to the boost volume can be increased while keeping low doses to the elective volumes, and the number of fractions and overall treatment time will be reduced, translating into better radiobiological effectiveness. In recent years, volumetric-modulated arc therapy (VMAT) has been shown to provide similar plan quality with respect to fixed-field IMRT but with large reduction in treatment time and monitor units (MUs) number. However, the feasibility of VMAT when used with SIB strategy has few investigations to date. We explored the potential of VMAT in a SIB strategy for complex cancer sites. A total of 15 patients were selected, including 5 head-and-neck, 5 high-risk prostate, and 5 rectal cancer cases. Both a double-arc VMAT and a 7-field IMRT plan were generated for each case using Oncentra MasterPlan treatment planning system for an Elekta Precise linac. Dosimetric indexes for targets and organs at risk (OARs) were compared based on dose-volume histograms. Conformity index, homogeneity index, and dose-contrast index were used for target analyses. The equivalent uniform doses and the normal tissue complication probabilities were calculated for main OARs. MUs number and treatment time were analyzed to score treatment efficiency. Pretreatment dosimetry was performed using 2-dimensional (2D)-array dosimeter. SIB-VMAT plans showed a high level of fluence modulation needed for SIB treatments, high conformal dose distribution, similar target coverage, and a tendency to improve OARs sparing compared with the benchmark SIB-IMRT plans. The median treatment times reduced from 13 to 20 minutes to approximately 5 minutes for all cases with SIB-VMAT, with a MUs reduction up to 22.5%. The 2D-array ion-chambers' measurements reported an agreement

  8. A method of simulating intensity modulation-direct detection WDM systems

    Institute of Scientific and Technical Information of China (English)

    HUANG Jing; YAO Jian-quan; LI En-bang

    2005-01-01

    In the simulation of Intensity Modulation-Direct Detection WDM Systems,when the dispersion and nonlinear effects play equally important roles,the intensity fluctuation caused by cross-phase modulation may be overestimated as a result of the improper step size.Therefore,the step size in numerical simulation should be selected to suppress false XPM intensity modulation (keep it much less than signal power).According to this criterion,the step size is variable along the fiber.For a WDM system,the step size depends on the channel separation.Different type of transmission fiber has different step size.In the split-step Fourier method,this criterion can reduce simulation time,and when the step size is bigger than 100 meters,the simulation accuracy can also be improved.

  9. Toward automated quality assurance for intensity- modulated radiation therapy

    International Nuclear Information System (INIS)

    Purpose: To investigate whether high-quality, relatively inexpensive, document and transparency scanners used as densitometers are sufficiently quantitative for routine quality assurance (QA). Methods and Materials: The scanner we investigated used a linear amplifier, digitizing gray-scale images to 12-bit resolution with a user-selected spatial resolution of 0.170 mm2 pixels. To reduce Newton's rings artifacts, the standard glass platen was replaced by glass with an antireflective coating. Conversion of reading to transmission was conducted by permanently placing a calibrated photographic step tablet on the scanner platen. After conversion to light transmission, a zero-phase two-dimensional Wiener filter was used to reduce pixel-to-pixel signal variation. Light-scatter artifacts were removed by deconvolution of a measured light-spread kernel. The light-spread kernel artifacts were significant along the scanner's detector axis, but were insignificant along the scanning axis. Results: Pixel-to-pixel noise was better than 2% for optical densities, ranging from 0.4 to 2.0 and 0 to 2.7 for the unfiltered and filtered images, respectively. The document scanning system response was compared against a confocal scanning laser densitometer. A series of IMRT dose distribution and dose calibration film sets were scanned using the two scanners, and the measured dose was compared. The maximum mean and standard deviation of the measured dose difference between the document scanner and confocal scanner was 1.48% and 1.06%, respectively. Conclusion: While the document scanners are not as flexible as dedicated film densitometers, these results indicate that, using the intensity and scatter corrections, the system provides accurate and precise measurements up to an optical density of 2.0, sufficient for routine IMRT film QA. For some film types, this requires the reduction in monitor units to limit the dose delivered to the film. The user must be cautious that the delivered IMRT

  10. Local region statistics combining multi-parameter intensity fitting module for medical image segmentation with intensity inhomogeneity and complex composition

    Science.gov (United States)

    Zhao, Fan; Zhao, Jian; Zhao, Wenda; Qu, Feng; Sui, Long

    2016-08-01

    It is difficult to segment medical image with intensity inhomogeneity and complex composition, because most region-based modules relay on the intensity distributions. In this paper, we propose a novel method which uses local region statistics and multi-parameter intensity fitting as well. By replacing the original local region statistics with the novel local region statistics after bias field correction, the effect of intensity inhomogeneity can be eliminated. Then we devise a maximum likelihood energy function based on the distribution of each local region. Segmentation and bias field estimation can be jointly obtained by minimizing the proposed energy function. Furthermore, in order to characterize the features of each local region effectively, two parameters are used to fit the average intensity inside and outside of the counter, respectively. This can well handle the medical images with complex composition, such as larger gray difference even in the same region. Comparisons with several representative methods on synthetic and medical images demonstrate the superiority of the proposed method over other representative algorithms.

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

    Directory of Open Access Journals (Sweden)

    Foroudi Farshad

    2012-07-01

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

  12. Acute toxicity profile of craniospinal irradiation with intensity-modulated radiation therapy in children with medulloblastoma: A prospective analysis

    International Nuclear Information System (INIS)

    To report on the acute toxicity in children with medulloblastoma undergoing intensity-modulated radiation therapy (IMRT) with daily intrafractionally modulated junctions. Newly diagnosed patients, aged 3–21, with standard-risk (SR) or high-risk (HR) medulloblastoma were eligible. A dose of 23.4 or 36.0Gy in daily fractions of 1.8Gy was prescribed to the craniospinal axis, followed by a boost to the primary tumor bed (54 or 55.8Gy) and metastases (39.6–55.8Gy), when indicated. Weekly, an intravenous bolus of vincristine was combined for patients with SR medulloblastoma and patients participating in the COG-ACNS-0332 study. Common toxicity criteria (CTC, version 2.0) focusing on skin, alopecia, voice changes, conjunctivitis, anorexia, dysphagia, gastro-intestinal symptoms, headache, fatigue and hematological changes were scored weekly during radiotherapy. From 2010 to 2014, data from 15 consecutive patients (SR, n = 7; HR, n = 8) were collected. Within 72 h from onset of treatment, vomiting (66 %) and headache (46 %) occurred. During week 3 of treatment, a peak incidence in constipation (33 %) and abdominal pain/cramping (40 %) was observed, but only in the subgroup of patients (n = 9) receiving vincristine (constipation: 56 vs 0 %, P = .04; pain/cramping: 67 vs 0 %, P = .03). At week 6, 73 % of the patients developed faint erythema of the cranial skin with dry desquamation (40 %) or moist desquamation confined to the skin folds of the auricle (33 %). No reaction of the skin overlying the spinal target volume was observed. Headache at onset and gastro-intestinal toxicity, especially in patients receiving weekly vincristine, were the major complaints of patients with medulloblastoma undergoing craniospinal irradiation with IMRT

  13. Shared data for intensity modulated radiation therapy (IMRT) optimization research: the CORT dataset

    OpenAIRE

    Craft, David; Bangert, Mark; Long, Troy; Papp, Dávid; Unkelbach, Jan

    2014-01-01

    Background: We provide common datasets (which we call the CORT dataset: common optimization for radiation therapy) that researchers can use when developing and contrasting radiation treatment planning optimization algorithms. The datasets allow researchers to make one-to-one comparisons of algorithms in order to solve various instances of the radiation therapy treatment planning problem in intensity modulated radiation therapy (IMRT), including beam angle optimization, volumetric modulated ar...

  14. Intensity-modulated radiotherapy for lung cancer: current status and future developments

    OpenAIRE

    Chan, C; Lang, S.; Rowbottom, C; Guckenberger, M.; Faivre-Finn, C

    2014-01-01

    Radiotherapy plays an important role in the management of lung cancer, with over 50% of patients receiving this modality at some point during their treatment. Intensity-modulated radiotherapy (IMRT) is a technique that adds fluence modulation to beam shaping, which improves radiotherapy dose conformity around the tumor and spares surrounding normal structures. Treatment with IMRT is becoming more widely available for the treatment of lung cancer, despite the paucity of high level evidence sup...

  15. Detection of an intense polychromatic gamma beam modulated at 3000 MHz

    International Nuclear Information System (INIS)

    This paper presents two methods of detection of a γ beam modulated at very high frequencies. The intense modulated beam is created by means of Bremsstrahlung in a gold-target, the latter having been placed in the emerging electron beam of the Linac at Saclay. A tentative interpretation of the physical phenomena involved in the detection processes is also given. The empirical data agree reasonably well with numerical evaluations based on well established theoretical concepts concerning these phenomena. (authors)

  16. Reduction of zero-order spatial frequencies by using binary intensity and phase modulations in holographic data storage

    OpenAIRE

    Fernández Varó, Elena; Márquez Ruiz, Andrés; Piñol, Diego; Padilla, Javier; Pascual Villalobos, Inmaculada

    2011-01-01

    Holographic data storage is a new optical technology which allows storing an important number of bits in a recording material. In this work, two different types of modulations, defocused binary intensity modulation and phase modulation, are compared to obtain which modulation could be the most suitable for holographic data storage. The best modulation would be the modulation with a homogeneous distribution of energy in the FT plane with no zero frequency peak.

  17. Very high-capacity short-reach VCSEL systems exploiting multicarrier intensity modulation and direct detection.

    Science.gov (United States)

    Gatto, Alberto; Argenio, Debora; Boffi, Pierpaolo

    2016-06-13

    Multicarrier intensity modulation of a bandwidth-limited long-wavelength VCSEL is exploited combined to direct detection to achieve very high capacity simple systems for short-reach applications. Tailored FDM subcarriers modulation and allocation allow to match the non-uniform frequency response of the system induced by the direct modulation and detection of the FDM signal and by the uncompensated SSMF propagation, overcoming the VCSEL bandwidth limitations. A whole transported throughput ranging from 34 Gb/s to 25 Gb/s from few hundreds meters to 20 km of SSMF propagation is experimentally demonstrated even by employing a 5-GHz band VCSEL source. PMID:27410296

  18. Switching circuit to improve the frequency modulation difference-intensity THz quantum cascade laser imaging

    OpenAIRE

    Saat, NK; Dean, P.; Khanna, SP; Salih, M; Linfield, EH; Davies, AG

    2015-01-01

    We demonstrate new switching circuit for difference-intensity THz quantum cascade laser (QCL) imaging by amplitude modulation and lock in detection. The switching circuit is designed to improve the frequency modulation so that it can stably lock the amplitude modulation of the QCL and the detector output. The combination of a voltage divider and a buffer in switching circuit to quickly switch the amplitude of the QCL biases of 15.8 V and 17.2 V is successfully to increase the frequency modula...

  19. Volumetric Modulated Arc Therapy Planning for Primary Prostate Cancer With Selective Intraprostatic Boost Determined by {sup 18}F-Choline PET/CT

    Energy Technology Data Exchange (ETDEWEB)

    Kuang, Yu [Department of Medical Physics, University of Nevada Las Vegas, Las Vegas, Nevada (United States); Wu, Lili [Department of Medical Physics, University of Nevada Las Vegas, Las Vegas, Nevada (United States); Department of Radiation Oncology, Cancer Hospital of Shantou University Medical College, Shantou, Guangdong (China); Hirata, Emily; Miyazaki, Kyle; Sato, Miles [Hamamatsu/Queen' s PET Imaging Center and Departments of Radiation Oncology and Oncology Research, The Queen' s Medical Center, Honolulu, Hawaii (United States); Kwee, Sandi A., E-mail: kwee@hawaii.edu [Hamamatsu/Queen' s PET Imaging Center and Departments of Radiation Oncology and Oncology Research, The Queen' s Medical Center, Honolulu, Hawaii (United States); John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii (United States)

    2015-04-01

    Purpose: This study evaluated expected tumor control and normal tissue toxicity for prostate volumetric modulated arc therapy (VMAT) with and without radiation boosts to an intraprostatically dominant lesion (IDL), defined by {sup 18}F-choline positron emission tomography/computed tomography (PET/CT). Methods and Materials: Thirty patients with localized prostate cancer underwent {sup 18}F-choline PET/CT before treatment. Two VMAT plans, plan{sub 79} {sub Gy} and plan{sub 100-105} {sub Gy}, were compared for each patient. The whole-prostate planning target volume (PTV{sub prostate}) prescription was 79 Gy in both plans, but plan{sub 100-105} {sub Gy} added simultaneous boost doses of 100 Gy and 105 Gy to the IDL, defined by 60% and 70% of maximum prostatic uptake on {sup 18}F-choline PET (IDL{sub suv60%} and IDL{sub suv70%}, respectively, with IDL{sub suv70%} nested inside IDL{sub suv60%} to potentially enhance tumor specificity of the maximum point dose). Plan evaluations included histopathological correspondence, isodose distributions, dose-volume histograms, tumor control probability (TCP), and normal tissue complication probability (NTCP). Results: Planning objectives and dose constraints proved feasible in 30 of 30 cases. Prostate sextant histopathology was available for 28 cases, confirming that IDL{sub suv60%} adequately covered all tumor-bearing prostate sextants in 27 cases and provided partial coverage in 1 case. Plan{sub 100-105} {sub Gy} had significantly higher TCP than plan{sub 79} {sub Gy} across all prostate regions for α/β ratios ranging from 1.5 Gy to 10 Gy (P<.001 for each case). There were no significant differences in bladder and femoral head NTCP between plans and slightly lower rectal NTCP (endpoint: grade ≥ 2 late toxicity or rectal bleeding) was found for plan{sub 100-105} {sub Gy}. Conclusions: VMAT can potentially increase the likelihood of tumor control in primary prostate cancer while observing normal tissue tolerances through

  20. Transverse intensity distributions of a broadband laser modulated by a hard-edged aperture.

    Science.gov (United States)

    Peng, Runwu; Ye, Yunxia; Tang, Zhixiang; Fan, Dianyuan

    2005-09-01

    By means of the Huygens-Fresnel diffraction integral, the field representation of a laser beam modulated by a hard-edged aperture is derived. The near-field and far-field transverse intensity distributions of the beams with different bandwidths are analyzed by using the representation. The numerical calculation results indicate that the amplitudes and numbers of the intensity spikes decrease with increasing bandwidth, and beam smoothing is achieved when the bandwidth takes a certain value in the near field. In the far field, the radius of the transverse intensity distribution decreases as the bandwidth increases, and the physical explanation of this fact is also given. PMID:16211818

  1. Head and neck intensity modulated radiation therapy leads to an increase of opportunistic oral pathogens

    NARCIS (Netherlands)

    Schuurhuis, Jennifer M.; Stokman, Monique A.; Witjes, Max J. H.; Langendijk, Johannes A.; van Winkelhoff, Arie J.; Vissink, Arjan; Spijkervet, Frederik K. L.

    2016-01-01

    Objectives: The introduction of intensity modulated radiation therapy (IMRT) has led to new possibilities in the treatment of head and neck cancer (HNC). Limited information is available on how this more advanced radiation technique affects the oral microflora. In a prospective study we assessed the

  2. Head and neck intensity modulated radiation therapy leads to an increase of opportunistic oral pathogens

    NARCIS (Netherlands)

    Schuurhuis, Jennifer M; Stokman, Monique A; Witjes, Max J H; Langendijk, Johannes A; van Winkelhoff, Arie J; Vissink, Arjan; Spijkervet, Frederik K L

    2016-01-01

    OBJECTIVES: The introduction of intensity modulated radiation therapy (IMRT) has led to new possibilities in the treatment of head and neck cancer (HNC). Limited information is available on how this more advanced radiation technique affects the oral microflora. In a prospective study we assessed the

  3. Optimizing Planning and Delivery of High-Precision Robotic Radiotherapy and Intensity-Modulated Proton Therapy

    NARCIS (Netherlands)

    S. van de Water (Steven)

    2015-01-01

    markdownabstract__Abstract__ High-precision robotic radiotherapy and intensity-modulated proton therapy (IMPT) are two relatively new radiotherapy techniques that particularly aim at a highly localized delivery of a curative dose to the tumor, while achieving excellent sparing of the surrounding he

  4. A preliminary investigation of cell growth after irradiation using a modulated x-ray intensity pattern

    International Nuclear Information System (INIS)

    In this study we have investigated a spatial distribution of cell growth after their irradiation using a modulated x-ray intensity pattern. An A549 human non-small cell lung cancer cell line was grown in a 6-well culture. Two of the wells were the unirradiated control wells, whilst another two wells were irradiated with a modulated x-ray intensity pattern and the third two wells were uniformly irradiated. A number of plates were incubated for various times after irradiation and stained with crystal violet. The spatial distribution of the stained cells within each well was determined by measurement of the crystal violet optical density at multiple positions in the plate using a microplate photospectrometer. The crystal violet optical density for a range of cell densities was measured for the unirradiated well and this correlated with cell viability as determined by the MTT cell viability assay. An exponential dose response curve was measured for A549 cells from the average crystal violet optical density in the uniformly irradiated well up to a dose of 30 Gy. By measuring the crystal violet optical density distribution within a well the spatial distribution of cell growth after irradiation with a modulated x-ray intensity pattern can be plotted. This method can be used for in vitro investigation into the changes in radiation response associated with treatment using intensity modulated radiation therapy (IMRT)

  5. Intensity Modulation of Hybrid Soliton Pulsed Source with Fibre Bragg Grating External Cavity

    Institute of Scientific and Technical Information of China (English)

    Nuran Dogru; M.Sadettin Ozyazici

    2004-01-01

    Resonance peak spectral splitting (RPSS) in the intensity modulation of a hybrid soliton pulsed source, where fibre Bragg gratings are used as an external cavity, can be suppressed by introducing a suitable linear chirp rate in a Gaussian apodized grating. Antireflection-coated reflectivity and gain suppression factor does not strongly affect the RPSS.

  6. A preliminary investigation of cell growth after irradiation using a modulated x-ray intensity pattern

    Science.gov (United States)

    Bromley, Regina; Davey, Ross; Oliver, Lyn; Harvie, Rozelle; Baldock, Clive

    2006-08-01

    In this study we have investigated a spatial distribution of cell growth after their irradiation using a modulated x-ray intensity pattern. An A549 human non-small cell lung cancer cell line was grown in a 6-well culture. Two of the wells were the unirradiated control wells, whilst another two wells were irradiated with a modulated x-ray intensity pattern and the third two wells were uniformly irradiated. A number of plates were incubated for various times after irradiation and stained with crystal violet. The spatial distribution of the stained cells within each well was determined by measurement of the crystal violet optical density at multiple positions in the plate using a microplate photospectrometer. The crystal violet optical density for a range of cell densities was measured for the unirradiated well and this correlated with cell viability as determined by the MTT cell viability assay. An exponential dose response curve was measured for A549 cells from the average crystal violet optical density in the uniformly irradiated well up to a dose of 30 Gy. By measuring the crystal violet optical density distribution within a well the spatial distribution of cell growth after irradiation with a modulated x-ray intensity pattern can be plotted. This method can be used for in vitro investigation into the changes in radiation response associated with treatment using intensity modulated radiation therapy (IMRT).

  7. A preliminary investigation of cell growth after irradiation using a modulated x-ray intensity pattern

    Energy Technology Data Exchange (ETDEWEB)

    Bromley, Regina [Northern Sydney Cancer Centre, Radiation Oncology, Royal North Shore Hospital, Sydney, NSW 2065 (Australia); Davey, Ross [Institute of Medical Physics, School of Physics, Sydney University, NSW 2006 (Australia); Oliver, Lyn [Northern Sydney Cancer Centre, Radiation Oncology, Royal North Shore Hospital, Sydney, NSW 2065 (Australia); Harvie, Rozelle [Institute of Medical Physics, School of Physics, Sydney University, NSW 2006 (Australia); Baldock, Clive [Bill Walsh Cancer Research Laboratories, Department of Medical Oncology, Royal North Shore Hospital, Sydney, NSW 2065 (Australia)

    2006-08-07

    In this study we have investigated a spatial distribution of cell growth after their irradiation using a modulated x-ray intensity pattern. An A549 human non-small cell lung cancer cell line was grown in a 6-well culture. Two of the wells were the unirradiated control wells, whilst another two wells were irradiated with a modulated x-ray intensity pattern and the third two wells were uniformly irradiated. A number of plates were incubated for various times after irradiation and stained with crystal violet. The spatial distribution of the stained cells within each well was determined by measurement of the crystal violet optical density at multiple positions in the plate using a microplate photospectrometer. The crystal violet optical density for a range of cell densities was measured for the unirradiated well and this correlated with cell viability as determined by the MTT cell viability assay. An exponential dose response curve was measured for A549 cells from the average crystal violet optical density in the uniformly irradiated well up to a dose of 30 Gy. By measuring the crystal violet optical density distribution within a well the spatial distribution of cell growth after irradiation with a modulated x-ray intensity pattern can be plotted. This method can be used for in vitro investigation into the changes in radiation response associated with treatment using intensity modulated radiation therapy (IMRT)

  8. Hybrid intensity-modulation-to-phase-remodulation optical wavelength reuse transport system

    Science.gov (United States)

    Chang, Ching-Hung; Tseng, Meng-Chun; Tseng, Cheng-Han

    2015-12-01

    A hybrid intensity-modulation (IM)-to-phase-remodulation optical wavelength reuse transport system is proposed and demonstrated experimentally. Based on the transport system, an optical carrier can be intensity-modulated with an orthogonal frequency-division multiplexing (OFDM) signal and then phase-remodulated with a radio frequency (RF) signal prior to communicating its destination through a span of single mode fiber. The OFDM signal at the receiver end can be directly detected using a photodetector (PD), and the phase-modulated RF signal can be detected by another PD after being converted back to intensity-modulation format by a semiconductor laser. In this study, the working window of the semiconductor laser-composed phase-modulation-format-to-IM-format converter is not fixed. The converter can be flexibly adjusted to align with the wavelength of the employed optical carrier. Experimental results prove that both OFDM and RF signals can be clearly detected with an error-free transmission. Evident interference is not found between both signals at the receiver end.

  9. Randomised trial of standard 2D radiotherapy (RT) versus intensity modulated radiotherapy (IMRT) in patients prescribed breast radiotherapy

    International Nuclear Information System (INIS)

    Background: Radiation dose distributions created by two dimensional (2D) treatment planning are responsible for partial volumes receiving >107% of the prescribed dose in a proportion of patients prescribed whole breast radiotherapy after tumour excision of early breast cancer. These may contribute to clinically significant late radiation adverse effects. Aim: To test three dimensional (3D) intensity modulated radiotherapy (IMRT) against 2D dosimetry using standard wedge compensators in terms of late adverse effects after whole breast radiotherapy. Methods: Three hundred and six women prescribed whole breast radiotherapy after tumour excision for early stage cancer were randomised to 3D IMRT (test arm) or 2D radiotherapy delivered using standard wedge compensators (control arm). All patients were treated with 6 or 10 MV photons to a dose of 50 Gy in 25 fractions to 100% in 5 weeks followed by an electron boost to the tumour bed of 11.1 Gy in 5 fractions to 100%. The primary endpoint was change in breast appearance scored from serial photographs taken before radiotherapy and at 1, 2 and 5 years follow up. Secondary endpoints included patient self-assessments of breast discomfort, breast hardness, quality of life and physician assessments of breast induration. Analysis was by intention to treat. Results: 240 (79%) patients with 5-year photographs were available for analysis. Change in breast appearance was identified in 71/122 (58%) allocated standard 2D treatment compared to only 47/118 (40%) patients allocated 3D IMRT. The control arm patients were 1.7 times more likely to have a change in breast appearance than the IMRT arm patients after adjustment for year of photographic assessment (95% confidence interval 1.2-2.5, p = 0.008). Significantly fewer patients in the 3D IMRT group developed palpable induration assessed clinically in the centre of the breast, pectoral fold, infra-mammary fold and at the boost site. No significant differences between treatment groups

  10. Accommodating practical constraints for intensity-modulated radiation therapy by means of compensators

    CERN Document Server

    Meyer, J

    2001-01-01

    intensity distribution, inverse modelling of the radiation attenuation within the compensator is required. Two novel and independent approaches, based on deconvolution and system identification, respectively, are proposed to accomplish this. To compare the approach with the 'rival' state of the art beam modulation technique, theoretical and experimental examination of the modulated fields generated by manufactured compensators and multileaf collimators is presented. This comparison focused on the achievable resolution of the intensity modulated beams in lateral and longitudinal directions. To take into account the characteristics of a clinical environment, a comprehensive study has been carried out to investigate the suitability of the most common commercially available treatment couch systems for their suitability for IMRT treatments. In this context, an original rule based advisory system has been developed to alert the operator of any potential collision of the beam with the moveable supporting structures ...

  11. Tunable and reconfigurable single passband filter using stimulated Brillouin scattering and intensity modulation

    Science.gov (United States)

    Hu, Shuling; Xiao, Zeyu; Wang, Huanhuan

    2015-07-01

    A tunable and reconfigurable single passband microwave photonic filter based on stimulated Brillouin scattering (SBS) and intensity modulation is presented and theoretically analyzed. Three Brillouin pumps with equal intensity are generated by selecting appropriate bias voltages and modulation indices. Then a reconfigurable passband can be achieved by superposition of the three pumps. Simulation results demonstrate that the proposed filter has a 22-GHz continuous tuning range with a high out-of-band rejection ratio above 40 dB. The -3-dB bandwidth can be tuned from 12 to 95 MHz, and the flatness is less than 1.5 dB. This technique uses a low-frequency (0 to 35 MHz) modulation signal to realize passband reshaping, and has potential applications in communication and radar systems.

  12. Intensity-modulated radiation therapy: overlapping co-axial modulated fields

    Energy Technology Data Exchange (ETDEWEB)

    Metcalfe, P [Centre for Medical Radiation Physics, University of Wollongong, NSW (Australia); Tangboonduangjit, P [Centre for Medical Radiation Physics, University of Wollongong, NSW (Australia); White, P [Nepean Cancer Care Centre, Sydney, NSW (Australia)

    2004-08-21

    The Varian multi-leaf collimator has a 14.5 cm leaf extension limit from each carriage. This means the target volumes in the head and neck region are sometimes too wide for standard width-modulated fields to provide adequate dose coverage. A solution is to set up asymmetric co-axial overlapping fields. This protects the MLC carriage while in return the MLC provides modulated dose blending in the field overlap region. Planar dose maps for coincident fields from the Pinnacle radiotherapy treatment planning system are compared with planar dose maps reconstructed from radiographic film and electronic portal images. The film and portal images show small leaf-jaw matchlines at each field overlap border. Linear profiles taken across each image show that the observed leaf-jaw matchlines from the accelerator images are not accounted for by the treatment planning system. Dose difference between film reconstructed electronic portal images and planning system are about 2.5 cGy in a modulated field at d{sub max}. While the magnitude of the dose differences are small improved round end leaf modelling combined with a finer dose calculation grid may minimize the discrepancy between calculated and delivered dose.

  13. Treatment of locally advanced carcinomas of head and neck with intensity-modulated radiation therapy (IMRT) in combination with cetuximab and chemotherapy: the REACH protocol

    International Nuclear Information System (INIS)

    Primary treatment of carcinoma of the oro-/hypopharynx or larynx may consist of combined platinum-containing chemoradiotherapy. In order to improve clinical outcome (i.e. local control/overall survival), combined therapy is intensified by the addition of the EGFR inhibitor cetuximab (Erbitux®). Radiation therapy (RT) is carried out as intensity-modulated RT (IMRT) to avoid higher grade acute and late toxicity by sparing of surrounding normal tissues. The REACH study is a prospective phase II study combining chemoradiotherapy with carboplatin/5-Fluorouracil (5-FU) and the monoclonal epidermal growth factor-receptor (EGFR) antibody cetuximab (Erbitux®) as intensity-modulated radiation therapy in patients with locally advanced squamous-cell carcinomas of oropharynx, hypopharynx or larynx. Patients receive weekly chemotherapy infusions in the 1st and 5th week of RT. Additionally, cetuximab is administered weekly throughout the treatment course. IMRT is delivered as in a classical concomitant boost concept (bid from fraction 16) to a total dose of 69,9 Gy. Primary endpoint of the trial is local-regional control (LRC). Disease-free survival, progression-free survival, overall survival, toxicity, proteomic and genomic analyses are secondary endpoints. The aim is to explore the efficacy as well as the safety and feasibility of this combined radioimmunchemotherapy in order to improve the outcome of patients with advanced head and neck cancer. ISRCTN87356938

  14. Treatment of locally advanced carcinomas of head and neck with intensity-modulated radiation therapy (IMRT in combination with cetuximab and chemotherapy: the REACH protocol

    Directory of Open Access Journals (Sweden)

    Simon Christian

    2010-11-01

    Full Text Available Abstract Background Primary treatment of carcinoma of the oro-/hypopharynx or larynx may consist of combined platinum-containing chemoradiotherapy. In order to improve clinical outcome (i.e. local control/overall survival, combined therapy is intensified by the addition of the EGFR inhibitor cetuximab (Erbitux®. Radiation therapy (RT is carried out as intensity-modulated RT (IMRT to avoid higher grade acute and late toxicity by sparing of surrounding normal tissues. Methods/Design The REACH study is a prospective phase II study combining chemoradiotherapy with carboplatin/5-Fluorouracil (5-FU and the monoclonal epidermal growth factor-receptor (EGFR antibody cetuximab (Erbitux® as intensity-modulated radiation therapy in patients with locally advanced squamous-cell carcinomas of oropharynx, hypopharynx or larynx. Patients receive weekly chemotherapy infusions in the 1st and 5th week of RT. Additionally, cetuximab is administered weekly throughout the treatment course. IMRT is delivered as in a classical concomitant boost concept (bid from fraction 16 to a total dose of 69,9 Gy. Discussion Primary endpoint of the trial is local-regional control (LRC. Disease-free survival, progression-free survival, overall survival, toxicity, proteomic and genomic analyses are secondary endpoints. The aim is to explore the efficacy as well as the safety and feasibility of this combined radioimmunchemotherapy in order to improve the outcome of patients with advanced head and neck cancer. Trial registration ISRCTN87356938

  15. Parameter study for polymer solar modules based on various cell lengths and light intensities

    Energy Technology Data Exchange (ETDEWEB)

    Slooff, L.H.; Burgers, A.R.; Bende, E.E.; Kroon, J.M. [ECN Solar Energy, P.O. Box 1, 1755 ZG Petten (Netherlands); Veenstra, S.C. [ECN Solar Energy, Solliance, High Tech Campus 5, P63, 5656AE Eindhoven (Netherlands)

    2013-10-15

    Polymer solar cells may be applied in portable electronic devices, where light intensity and spectral distribution of the illuminating source can be very different compared to outdoor applications. As the power output of solar cells depends on temperature, light intensity and spectrum, the design of the module must be optimized for the specific illumination conditions in the different applications. The interconnection area between cells in a module must be as narrow as possible to maximize the active area, also called geometrical fill factor, of the module. Laser scribing has the potential to realize this. The optimal width of the interconnection zone depends both on technological limitations, e.g. laser scribe width and the minimal distance between scribes, and electrical limitations like resistive losses. The latter depends on the generated current in the cell and thus also on illumination intensity. Besides that, also the type of junction, i.e. a single or tandem junction, will influence the optimal geometry. In this paper a calculation model is presented that can be used for electrical modeling of polymer cells and modules in order to optimize the performance for the specific illumination conditions.

  16. Spectral lineshape and noise of semiconductor lasers under analog intensity modulation

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Moustafa [Department of Physics, Faculty of Science, Minia University, 61519 El-Minia (Egypt)], E-mail: m.farghal@link.net

    2008-09-07

    Intensity and frequency fluctuations of semiconductor lasers under analog intensity modulation are theoretically investigated in both time and frequency domains. The spectral properties of the relative intensity noise (RIN) and the frequency noise (FN) as well as the associated lineshape are examined as functions of the modulation frequency and strength. The study is based on a numerical solution of the stochastic rate equations of semiconductor lasers. Based on the time variation of the photon number and the phase portrait of the photon number versus the electron number, the modulation dynamics are classified into six distinct types. The results showed that the high-frequency regimes of both RIN and FN are higher and the lineshape is more broadened when the signal is pulsed than when it varies continuously with time. The low-frequency components of RIN and FN are considerably enhanced and the laser coherency is extremely deteriorated when the laser emits irregular spike-like pulses under low-frequency strong modulation.

  17. Hypofractionated intensity-modulated arc therapy for lymph node metastasized prostate cancer: Early late toxicity and 3-year clinical outcome

    International Nuclear Information System (INIS)

    Background and purpose: For patients with N1 prostate cancer (PCa) aggressive local therapies can be advocated. We evaluated clinical outcome, gastro-intestinal (GI) and genito-urinary (GU) toxicity after intensity modulated arc radiotherapy (IMAT) + androgen deprivation (AD) for N1 PCa. Material and methods: Eighty patients with T1-4N1M0 PCa were treated with IMAT and 2–3 years of AD. A median dose of 69.3 Gy (normalized isoeffective dose at 2 Gy per fraction: 80 Gy [α/β = 3]) was prescribed in 25 fractions to the prostate. The pelvic lymph nodes received a minimal dose of 45 Gy. A simultaneous integrated boost to 72 Gy and 65 Gy was delivered to the intraprostatic lesion and/or pathologically enlarged lymph nodes, respectively. GI and GU toxicity was scored using the RTOG/RILIT and RTOG-SOMA/LENT-CTC toxicity scoring system respectively. Three-year actuarial risk of grade 2 and 3/4 GI–GU toxicity and biochemical and clinical relapse free survival (bRFS and cRFS) were calculated with Kaplan–Meier statistics. Results: Median follow-up was 36 months. Three-year actuarial risk for late grade 3 and 2 GI toxicity is 8% and 20%, respectively. Three-year actuarial risk for late grade 3–4 and 2 GU toxicity was 6% and 34%, respectively. Actuarial 3-year bRFS and cRFS was 81% and 89%, respectively. Actuarial 3-year bRFS and cRFS was, respectively 26% and 32% lower for patients with cN1 disease when compared to patients with cN0 disease. Conclusion: IMAT for N1 PCa offers good clinical outcome with moderate toxicity. Patients with cN1 disease have poorer outcome

  18. Intensity-modulated radiation therapy with concurrent chemotherapy for locally advanced cervical and upper thoracic esophageal cancer

    Institute of Scientific and Technical Information of China (English)

    Shu-Lian Wang; Zhongxing Liao; Helen Liu; Jaffer Ajani; Stephen Swisher; James D Cox; Ritsuko Komaki

    2006-01-01

    AIM: To evaluate the dosimetry, efficacy and toxicity of intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy for patients with locally advanced cervical and upper thoracic esophageal cancer.METHODS: A retrospective study was performed on 7 patients who were definitively treated with IMRT and concurrent chemotherapy. Patients who did not receive IMRT radiation and concurrent chemotherapy were not included in this analysis. IMRT plans were evaluated to assess the tumor coverage and normal tissue avoidance. Treatment response was evaluated and toxicities were assessed.RESULTS: Five- to nine-beam IMRT were used to deliver a total dose of 59.4-66 Gy (median: 64.8 Gy) to the primary tumor with 6-MV photons. The minimum dose received by the planning tumor volume (PTV) of the gross tumor volume boost was 91.2%-98.2% of the prescription dose (standard deviation [SD]: 3.7%-5.7%).tumor volume was 93.8%-104.8% (SD: 4.3%-11.1%)of the prescribed dose. With a median follow-up of 15 mo (range: 3-21 mo), all 6 evaluable patients achieved complete response. Of them, 2 developed local recurrences and 2 had distant metastases, 3 survived with no evidence of disease. After treatment, 2 patients developed esophageal stricture requiring frequent dilation and 1 patient developed tracheal-esophageal fistula.CONCLUSION: Concurrent IMRT and chemotherapy resulted in an excellent early response in patients with locally advanced cervical and upper thoracic esophageal cancer. However, local and distant recurrence and toxicity remain to be a problem. Innovative approaches are needed to improve the outcome.

  19. Intensity-Modulated Radiotherapy Results in Significant Decrease in Clinical Toxicities Compared With Conventional Wedge-Based Breast Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: We have previously demonstrated that intensity-modulated radiotherapy (IMRT) with a static multileaf collimator process results in a more homogenous dose distribution compared with conventional wedge-based whole breast irradiation (WBI). In the present analysis, we reviewed the acute and chronic toxicity of this IMRT approach compared with conventional wedge-based treatment. Methods and Materials: A total of 172 patients with Stage 0-IIB breast cancer were treated with lumpectomy followed by WBI. All patients underwent treatment planning computed tomography and received WBI (median dose, 45 Gy) followed by a boost to 61 Gy. Of the 172 patients, 93 (54%) were treated with IMRT, and the 79 patients (46%) treated with wedge-based RT in a consecutive fashion immediately before this cohort served as the control group. The median follow-up was 4.7 years. Results: A significant reduction in acute Grade 2 or worse dermatitis, edema, and hyperpigmentation was seen with IMRT compared with wedges. A trend was found toward reduced acute Grade 3 or greater dermatitis (6% vs. 1%, p = 0.09) in favor of IMRT. Chronic Grade 2 or worse breast edema was significantly reduced with IMRT compared with conventional wedges. No difference was found in cosmesis scores between the two groups. In patients with larger breasts (≥1,600 cm3, n = 64), IMRT resulted in reduced acute (Grade 2 or greater) breast edema (0% vs. 36%, p <0.001) and hyperpigmentation (3% vs. 41%, p 0.001) and chronic (Grade 2 or greater) long-term edema (3% vs. 30%, p 0.007). Conclusion: The use of IMRT in the treatment of the whole breast results in a significant decrease in acute dermatitis, edema, and hyperpigmentation and a reduction in the development of chronic breast edema compared with conventional wedge-based RT

  20. Breast Intensity-Modulated Radiation Therapy Reduces Time Spent With Acute Dermatitis for Women of All Breast Sizes During Radiation

    International Nuclear Information System (INIS)

    Purpose: To study the time spent with radiation-induced dermatitis during a course of radiation therapy for breast cancer in women treated with conventional or intensity-modulated radiation therapy (IMRT). Methods and Materials: The study population consisted of 804 consecutive women with early-stage breast cancer treated with breast-conserving surgery and radiation from 2001 to 2006. All patients were treated with whole-breast radiation followed by a boost to the tumor bed. Whole-breast radiation consisted of conventional wedged photon tangents (n = 405) earlier in the study period and mostly of photon IMRT (n = 399) in later years. All patients had acute dermatitis graded each week of treatment. Results: The breakdown of the cases of maximum acute dermatitis by grade was as follows: 3%, Grade 0; 34%, Grade 1; 61%, Grade 2; and 2%, Grade 3. The breakdown of cases of maximum toxicity by technique was as follows: 48%, Grade 0/1, and 52%, Grade 2/3, for IMRT; and 25%, Grade 0/1, and 75%, Grade 2/3, for conventional radiation therapy (p < 0.0001). The IMRT patients spent 82% of weeks during treatment with Grade 0/1 dermatitis and 18% with Grade 2/3 dermatitis, compared with 29% and 71% of patients, respectively, treated with conventional radiation (p < 0.0001). Furthermore, the time spent with Grade 2/3 toxicity was decreased in IMRT patients with small (p = 0.0015), medium (p < 0.0001), and large (p < 0.0001) breasts. Conclusions: Breast IMRT is associated with a significant decrease both in the time spent during treatment with Grade 2/3 dermatitis and in the maximum severity of dermatitis compared with that associated with conventional radiation, regardless of breast size.

  1. The potential benefit of swallowing sparing intensity modulated radiotherapy to reduce swallowing dysfunction: An in silico planning comparative study

    International Nuclear Information System (INIS)

    Purpose: To apply recently developed predictive models for swallowing dysfunction to compare the predicted probabilities of swallowing dysfunction for standard intensity modulated radiotherapy (ST-IMRT) and swallowing sparing IMRT (SW-IMRT). Materials and methods: Thirty head and neck cancer patients who previously underwent radiotherapy for the bilateral neck were selected for this study. For each patient, ST-IMRT and SW-IMRT simultaneous integrated boost treatment plans were created. ST-IMRT treatment plan optimisation aimed at obtaining adequate target volume coverage and sparing of the parotid and submandibular glands as much as possible. Objectives for SW-IMRT were similar, with additional objectives to spare the organs at risk related to swallowing dysfunction (SWOARs). Dose-volume data with ST-IMRT and SW-IMRT and normal tissue complication probabilities for physician-rated and patient-rated swallowing dysfunction were calculated with recently developed predictive models. Results: All plans had adequate target volume coverage and dose to critical organs was within accepted limits. Sparing of parotid glands was similar for ST-IMRT and SW-IMRT. With SW-IMRT, the mean dose to the various SWOARs was reduced. Absolute dose values and dose reductions with SW-IMRT differed per patient and per SWOAR and depended on N stage and tumour location. The mean reduction in predicted physician-rated Radiation Therapy Oncology Group (RTOG) grade 2–4 swallowing dysfunction was 9% (range, 3–20%). Mean reductions of the probability of patient-rated moderate to severe complaints with regard to the swallowing of solid food, soft food, liquid food and choking when swallowing were 8%, 2%, 1% and 1%, respectively. Conclusions: New predictive models for swallowing dysfunction were applied to show potential reductions in physician and patient-rated swallowing dysfunction with IMRT that was specifically optimised to spare SWOARs.

  2. Normalization of prostate specific antigen in patients treated with intensity modulated radiotherapy for clinically localized prostate cancer

    International Nuclear Information System (INIS)

    The purpose of this study was to determine the expected time to prostate specific antigen (PSA) normalization with or without neoadjuvant androgen deprivation (NAAD) therapy after treatment with intensity modulated radiotherapy (IMRT) for patients with clinically localized prostate cancer. A retrospective cohort research design was used. A total of 133 patients with clinical stage T1c to T3b prostate cancer (2002 AJCC staging) treated in a community setting between January 2002 and July 2005 were reviewed for time to PSA normalization using 1 ng/mL and 2 ng/mL as criteria. All patients received IMRT as part of their management. Times to PSA normalization were calculated using the Kaplan-Meier method. Significance was assessed at p < 0.05. Fifty-six of the 133 patients received NAAD (42.1%). Thirty-one patients (23.8%) received radiation to a limited pelvic field followed by an IMRT boost, while 99 patients received IMRT alone (76.2%). The times to serum PSA normalization < 2 ng/mL when treated with or without NAAD were 298 ± 24 and 302 ± 33 days (mean ± SEM), respectively (p > 0.05), and 303 ± 24 and 405 ± 46 days, respectively, for PSA < 1 ng/mL (p < 0.05). Stage T1 and T2 tumors had significantly increased time to PSA normalization < 1 ng/mL in comparison to Stage T3 tumors. Also, higher Gleason scores were significantly correlated with a faster time to PSA normalization < 1 ng/mL. Use of NAAD in conjunction with IMRT leads to a significantly shortened time to normalization of serum PSA < 1 ng/mL in patients with clinically localized prostate cancer

  3. Using a Reduced Spot Size for Intensity-Modulated Proton Therapy Potentially Improves Salivary Gland-Sparing in Oropharyngeal Cancer

    International Nuclear Information System (INIS)

    Purpose: To investigate whether intensity-modulated proton therapy with a reduced spot size (rsIMPT) could further reduce the parotid and submandibular gland dose compared with previously calculated IMPT plans with a larger spot size. In addition, it was investigated whether the obtained dose reductions would theoretically translate into a reduction of normal tissue complication probabilities (NTCPs). Methods: Ten patients with N0 oropharyngeal cancer were included in a comparative treatment planning study. Both IMPT plans delivered simultaneously 70 Gy to the boost planning target volume (PTV) and 54 Gy to the elective nodal PTV. IMPT and rsIMPT used identical three-field beam arrangements. In the IMPT plans, the parotid and submandibular salivary glands were spared as much as possible. rsIMPT plans used identical dose–volume objectives for the parotid glands as those used by the IMPT plans, whereas the objectives for the submandibular glands were tightened further. NTCPs were calculated for salivary dysfunction and xerostomia. Results: Target coverage was similar for both IMPT techniques, whereas rsIMPT clearly improved target conformity. The mean doses in the parotid glands and submandibular glands were significantly lower for three-field rsIMPT (14.7 Gy and 46.9 Gy, respectively) than for three-field IMPT (16.8 Gy and 54.6 Gy, respectively). Hence, rsIMPT significantly reduced the NTCP of patient-rated xerostomia and parotid and contralateral submandibular salivary flow dysfunction (27%, 17%, and 43% respectively) compared with IMPT (39%, 20%, and 79%, respectively). In addition, mean dose values in the sublingual glands, the soft palate and oral cavity were also decreased. Obtained dose and NTCP reductions varied per patient. Conclusions: rsIMPT improved sparing of the salivary glands and reduced NTCP for xerostomia and parotid and submandibular salivary dysfunction, while maintaining similar target coverage results. It is expected that rsIMPT improves

  4. Using a Reduced Spot Size for Intensity-Modulated Proton Therapy Potentially Improves Salivary Gland-Sparing in Oropharyngeal Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Water, Tara A. van de, E-mail: t.a.van.de.water@rt.umcg.nl [Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands); Lomax, Antony J. [Centre for Proton Therapy, Paul Scherrer Institute, Villigen-PSI (Switzerland); Bijl, Hendrik P.; Schilstra, Cornelis [Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands); Hug, Eugen B. [Centre for Proton Therapy, Paul Scherrer Institute, Villigen-PSI (Switzerland); Langendijk, Johannes A. [Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands)

    2012-02-01

    Purpose: To investigate whether intensity-modulated proton therapy with a reduced spot size (rsIMPT) could further reduce the parotid and submandibular gland dose compared with previously calculated IMPT plans with a larger spot size. In addition, it was investigated whether the obtained dose reductions would theoretically translate into a reduction of normal tissue complication probabilities (NTCPs). Methods: Ten patients with N0 oropharyngeal cancer were included in a comparative treatment planning study. Both IMPT plans delivered simultaneously 70 Gy to the boost planning target volume (PTV) and 54 Gy to the elective nodal PTV. IMPT and rsIMPT used identical three-field beam arrangements. In the IMPT plans, the parotid and submandibular salivary glands were spared as much as possible. rsIMPT plans used identical dose-volume objectives for the parotid glands as those used by the IMPT plans, whereas the objectives for the submandibular glands were tightened further. NTCPs were calculated for salivary dysfunction and xerostomia. Results: Target coverage was similar for both IMPT techniques, whereas rsIMPT clearly improved target conformity. The mean doses in the parotid glands and submandibular glands were significantly lower for three-field rsIMPT (14.7 Gy and 46.9 Gy, respectively) than for three-field IMPT (16.8 Gy and 54.6 Gy, respectively). Hence, rsIMPT significantly reduced the NTCP of patient-rated xerostomia and parotid and contralateral submandibular salivary flow dysfunction (27%, 17%, and 43% respectively) compared with IMPT (39%, 20%, and 79%, respectively). In addition, mean dose values in the sublingual glands, the soft palate and oral cavity were also decreased. Obtained dose and NTCP reductions varied per patient. Conclusions: rsIMPT improved sparing of the salivary glands and reduced NTCP for xerostomia and parotid and submandibular salivary dysfunction, while maintaining similar target coverage results. It is expected that rsIMPT improves quality

  5. Intensity modulated radiation therapy using laser-accelerated protons: a Monte Carlo dosimetric study

    International Nuclear Information System (INIS)

    In this paper we present Monte Carlo studies of intensity modulated radiation therapy using laser-accelerated proton beams. Laser-accelerated protons coming out of a solid high-density target have broad energy and angular spectra leading to dose distributions that cannot be directly used for therapeutic applications. Through the introduction of a spectrometer-like particle selection system that delivers small pencil beams of protons with desired energy spectra it is feasible to use laser-accelerated protons for intensity modulated radiotherapy. The method presented in this paper is a three-dimensional modulation in which the proton energy spectrum and intensity of each individual beamlet are modulated to yield a homogeneous dose in both the longitudinal and lateral directions. As an evaluation of the efficacy of this method, it has been applied to two prostate cases using a variety of beam arrangements. We have performed a comparison study between intensity modulated photon plans and those for laser-accelerated protons. For identical beam arrangements and the same optimization parameters, proton plans exhibit superior coverage of the target and sparing of neighbouring critical structures. Dose-volume histogram analysis of the resulting dose distributions shows up to 50% reduction of dose to the critical structures. As the number of fields is decreased, the proton modality exhibits a better preservation of the optimization requirements on the target and critical structures. It is shown that for a two-beam arrangement (parallel-opposed) it is possible to achieve both superior target coverage with 5% dose inhomogeneity within the target and excellent sparing of surrounding tissue

  6. PDM-16QAM vector signal generation and detection based on intensity modulation and direct detection

    Science.gov (United States)

    Chen, Long; Yu, Jianjun; Li, Xinying

    2016-07-01

    We experimentally demonstrate a novel and simple method to generate and detect high speed polarization-division-multiplexing 16-ary quadrature-amplitude-modulation (PDM-16QAM) vector signal enabled by Mach-Zehnder modulator-based (MZM-based) optical-carrier-suppression (OCS) intensity modulation and direct detection. Due to the adoption of OCS intensity modulation, carrier beating can be avoided at the receiver, and thus polarization de-multiplexing can be implemented by digital-signal-processing-based (DSP-based) cascaded multi-modulus algorithm (CMMA) equalization instead of a polarization tracking system. The change of both amplitude and phase information due to the adoption of OCS modulation can be equalized by DSP-based amplitude and phase precoding at the transmitter. Up to 64-Gb/s PDM-16QAM vector signal is generated and detected after 2-km single-mode fiber-28 (SMF-28) or 20-km large-effective-area fiber (LEAF) transmission with a bit-error-ratio (BER) less than the hard-decision forward-error-correction (HD-FEC) threshold of 3.8×10-3.

  7. Intensity-modulated linear-frequency-modulated continuous-wave lidar for distributed media: fundamentals of technique.

    Science.gov (United States)

    Batet, Oscar; Dios, Federico; Comeron, Adolfo; Agishev, Ravil

    2010-06-10

    We analyze the intensity-modulation frequency-modulated continuous-wave (FMCW) technique for lidar remote sensing in the context of its application to distributed media. The goal of the technique is the reproduction of the sounded-medium profile along the emission path. A conceptual analysis is carried out to show the problems the basic version of the method presents for this application. The principal point is the appearance of a bandpass filtering effect, which seems to hinder its use in this context. A modified version of the technique is proposed to overcome this problem. A number of computer simulations confirm the ability of the modified FMCW technique to sound distributed media. PMID:20539357

  8. Intensity modulated radiation therapy for head and neck cancer: The standard; Radiotherapie avec modulation d'intensite pour les cancers de la tete et du cou: le standard

    Energy Technology Data Exchange (ETDEWEB)

    Maingon, P.; Crehange, G.; Chamois, J.; Khoury, C.; Truc, G. [Departement de radiotherapie, centre Georges-Francois-Leclerc, 1, rue du Pr-Marion, 21079 Dijon cedex (France)

    2011-10-15

    Combined radical radiation therapy for head and neck carcinoma should be planned with intensity modulated beams to provide a rapid answer to patients' requirements in terms of quality of treatment. The most frequent late toxicity of radiation therapy is xerostomia, which may be prevented by using this technique able to significantly spare salivary glands irradiation. Selection of indications is a very important step. The objective of sparing salivary functions, strongly associated with optimization criteria of quality of life should be considered as a main objective in irradiation of head and neck tumours. The various possibilities offered by this technique allowing to boost a target volume included in prophylactically irradiated regions could offer the possibility to escalate the dose in selected patients. The feasibility of this process is currently validated in prospective studies. Finally, routine implementation of intensity modulated radiation therapy should be performed with strong and robust quality assurance procedures, ensuring that the expected benefit could be increased with the current developments by using rotational techniques. (authors)

  9. Two-tone intensity-modulated optical stimulus for self-referencing microwave characterization of high-speed photodetectors

    Science.gov (United States)

    Wang, Heng; Zhang, Shangjian; Zou, Xinhai; Zhang, Yali; Lu, Rongguo; Zhang, Zhiyao; Zhang, Xiaoxia; Liu, Yong

    2016-08-01

    The two-tone intensity modulated optical stimulus is proposed and demonstrated for measuring the high-frequency response of photodetectors. The method provides a narrow linewidth and wide bandwidth optical stimulus based on the two-tone modulation of a Mach-Zehnder electro-optical intensity modulator, and achieves the self-referenced measurement of photodetectors without the need for correcting the power variation of optical stimulus. Moreover, the two-tone intensity modulation method allows bias-independent measurement with doubled measuring frequency range. In the experiment, the consistency between our method and the conventional methods verifies the simple but accurate measurement.

  10. Volumetric Modulated Arc Radiotherapy for Early Stage Non-Small-Cell Lung Carcinoma: Is It Better Than the Conventional Static Beam Intensity Modulated Radiotherapy?

    OpenAIRE

    Vincent Wing Cheung Wu; Man In Pun; Cho Pan Lam; To Wing Mok; Wah Wai Mok

    2014-01-01

    This study compared the performance of volumetric modulated arc therapy (VMAT) techniques: single arc volumetric modulated arc therapy (SA-VMAT) and double arc volumetric modulated arc therapy (DA-VMAT) with the static beam conventional intensity modulated radiotherapy (C-IMRT) for non-small-cell lung carcinoma (NSCLC). Twelve stage I and II NSCLC patients were recruited and their planning CT with contoured planning target volume (PTV) and organs at risk (OARs) was used for planning. Using th...

  11. Performance Characteristics Of An Intensity Modulated Advanced X-Ray Source (IMAXS) For Homeland Security Applications

    International Nuclear Information System (INIS)

    X-ray cargo inspection systems for the detection and verification of threats and contraband must address stringent, competitive performance requirements. High x-ray intensity is needed to penetrate dense cargo, while low intensity is desirable to minimize the radiation footprint, i.e. the size of the controlled area, required shielding and the dose to personnel. In a collaborative effort between HESCO/PTSE Inc., XScell Corp., Stangenes Industries, Inc. and Rapiscan Laboratories, Inc., an Intensity Modulated Advanced X-ray Source (IMAXS) was designed and produced. Cargo inspection systems utilizing such a source have been projected to achieve up to 2 inches steel-equivalent greater penetration capability, while on average producing the same or smaller radiation footprint as present fixed-intensity sources. Alternatively, the design can be used to obtain the same penetration capability as with conventional sources, but reducing the radiation footprint by about a factor of three. The key idea is to anticipate the needed intensity for each x-ray pulse by evaluating signal strength in the cargo inspection system detector array for the previous pulse. The IMAXS is therefore capable of changing intensity from one pulse to the next by an electronic signal provided by electronics inside the cargo inspection system detector array, which determine the required source intensity for the next pulse. We report on the completion of a 9 MV S-band (2998 MHz) IMAXS source and comment on its performance.

  12. MIMO Free-Space Optical Communication Employing Subcarrier Intensity Modulation in Atmospheric Turbulence Channels

    Science.gov (United States)

    Ghassemlooy, Zabih; Popoola, Wasiu O.; Ahmadi, Vahid; Leitgeb, Erich

    In this paper, we analyse the error performance of transmitter/receiver array free-space optical (FSO) communication system employing binary phase shift keying (BPSK) subcarrier intensity modulation (SIM) in clear but turbulent atmospheric channel. Subcarrier modulation is employed to eliminate the need for adaptive threshold detector. Direct detection is employed at the receiver and each subcarrier is subsequently demodulated coherently. The effect of irradiance fading is mitigated with an array of lasers and photodetectors. The received signals are linearly combined using the optimal maximum ratio combining (MRC), the equal gain combining (EGC) and the selection combining (SelC). The bit error rate (BER) equations are derived considering additive white Gaussian noise and log normal intensity fluctuations. This work is part of the EU COST actions and EU projects.

  13. Optical Intensity Modulation in an LiNbO3 Slab-Coupled Waveguide

    Directory of Open Access Journals (Sweden)

    Yalin Lu

    2008-01-01

    Full Text Available Optical intensity modulation has been demonstrated through switching the optical beam between the main core waveguide and a closely attached leaky slab waveguide by applying a low-voltage electrical field. Theory for simulating such an LiNbO3 slab-coupled waveguide structure was suggested, and the result indicates the possibility of making the spatial guiding mode large, circular and symmetric, which further allows the potential to significantly reduce the coupling losses with adjacent lasers and optical networks. Optical intensity modulation using electro-optic effect was experimentally demonstrated in a 5 cm long waveguide fabricated by using a procedure of soft proton exchange and then an overgrowth of thin LN film on top of a c-cut LiNbO3 wafer.

  14. Implementation of intensity-modulated conformational radiotherapy for cervical cancers at the Alexis Vautrin Centre

    International Nuclear Information System (INIS)

    As platinum salt based concomitant conformational radiotherapy and chemotherapy have been used as a standard treatment for cervical cancers but resulted in digestive and haematological toxicities, this research thesis reports the application of intensity-modulated conformational radiation therapy. After having recalled some epidemiological, anatomical aspects, diagnosis and treatments aspects regarding cervical cancer, the author presents this last treatment technique (principles, benefits, practical implementation). The author discusses results obtained by an experiment during which seven patients have been treated by simple conformational radiation therapy, and four by intensity-modulated conformational radiation therapy. Results are discussed in terms of volumes (clinical target volume, growth target volume, planned target volume), dosimetric results, toxicities (urine and skin), weight loss

  15. Application of high power modulated intense relativistic electron beams for development of Wake Field Accelerator

    International Nuclear Information System (INIS)

    This final Progress Report addresses DOE-sponsored research on the development of future high-gradient particle accelerators. The experimental and the theoretical research, which lasted three years, investigated the Two Beam Accelerator (TBA). This high-voltage-gradient accelerator was powered by a modulated intense relativistic electron beam (MIREB) of power >1010 watts. This research was conceived after a series of successful experiments performed at NRL generating and using MIREBs. This work showed that an RF structure could be built which was directly powered by a modulated intense relativistic electron beam. This structure was then used to accelerate a second electron beam. At the end of the three year project the proof-of-principle accelerator demonstrated the generation of a high current beam of electrons with energy >60 MeV. Scaling laws needed to design practical devices for future applications were also derived

  16. Influence of stimulus intensity on the soleus H-reflex amplitude and modulation during locomotion

    DEFF Research Database (Denmark)

    Simonsen, Erik B; Alkjær, Tine; Raffalt, Peter C

    2013-01-01

    Diverging results have been reported regarding the modulation and amplitude of the soleus H-reflex measured during human walking and running. A possible explanation to this could be the use of too high stimulus strength in some studies while not in others. During activities like walking and running......-reflex methodology itself. Accordingly, the purpose of the present study was to study the effect on the soleus H-reflex during walking and running using stimulus intensities normally considered too high (up to 45% Mmax). Using M-waves of 25-45% Mmax as opposed to 5-25% Mmax showed a significant suppression of the...... peak H-reflex during the stance phase of walking, while no changes were observed during running. No differences were observed regarding modulation pattern. So a possible use of too high stimulus intensity cannot explain the differences mentioned. The surprising result in running may be explained by the...

  17. Wideband Analog Transmission System Based on the External Intensity Electro-Optic Modulator

    Directory of Open Access Journals (Sweden)

    Jiri Svarny

    2016-01-01

    Full Text Available The work deals with design and integration of an analog electro-optic transmission system suitable for some specialized tasks of diagnostics and measurements. The system is based on principle of external intensity modulation of fiber guided laser radiation. Besides wideband and almost lossless transmission the system tolerates extreme length of the transmitting medium and ensures ultimate galvanic barrier between the input and output.

  18. Efficacy of intensity-modulated radiotherapy for resected thoracic esophageal squamous cell carcinoma

    OpenAIRE

    Zhang, Wencheng; Liu, Xiao; Xiao, Zefen; Wang, Lvhua; Zhang, Hongxing; Chen, Dongfu; Zhou, Zongmei; Feng, Qinfu; Hui, Zhouguang; Liang, Jun; Yin, Weibo; He, Jie

    2015-01-01

    Background Little is known about the clinical use of intensity-modulated radiotherapy (IMRT) in postoperative radiotherapy (PORT) of esophageal cancer; therefore, we retrospectively investigated the clinical value of postoperative IMRT among resected thoracic esophageal squamous cell carcinoma (TESCC) patients. Methods We enrolled a total of 228 patients with resected TESCC who underwent IMRT between January 2004 and June 2009 in the study. PORT was applied via IMRT with a median total dose o...

  19. Treatment Outcomes of Helical Intensity-Modulated Radiotherapy for Unresectable Hepatocellular Carcinoma

    OpenAIRE

    Kong, Moonkyoo; Hong, Seong Eon; Choi, Woo Suk; Choi, Jinhyun; Kim, Youngkyong

    2013-01-01

    Background/Aims This study reports treatment outcomes after helical intensity-modulated radiotherapy (IMRT) in unresectable hepatocellular carcinoma (HCC) patients for whom transarterial chemoembolization (TACE) was considered ineffective or unsuitable. Methods From January 2008 to December 2011, 22 unresectable HCC patients received helical IMRT. A daily dose of 1.8 to 4 Gy was delivered at five fractions per week to deliver a total dose of 30 to 60 Gy. The most-prescribed dose fractionation...

  20. Tumor trailing strategy for intensity-modulated radiation therapy of moving targets

    OpenAIRE

    Trofimov, Alexei; Vrancic, Christian; Chan, Timothy C. Y.; Sharp, Gregory C.; Bortfeld, Thomas

    2008-01-01

    Internal organ motion during the course of radiation therapy of cancer affects the distribution of the delivered dose and, generally, reduces its conformality to the targeted volume. Previously proposed approaches aimed at mitigating the effect of internal motion in intensity-modulated radiation therapy (IMRT) included expansion of the target margins, motion-correlated delivery (e.g., respiratory gating, tumor tracking), and adaptive treatment plan optimization employing a probabilistic descr...

  1. Dosimetric and QA aspects of Konrad inverse planning system for commissioning intensity-modulated radiation therapy

    OpenAIRE

    Deshpande Shrikant; Sathiyanarayanan V; Bhangle Janhavi; Swamy Kumara; Basu Sumit

    2007-01-01

    The intensity-modulated radiation therapy (IMRT) planning is performed using the Konrad inverse treatment planning system and the delivery of the treatment by using Siemens Oncor Impression Plus linear accelerator (step and shoot), which has been commissioned recently. The basic beam data required for commissioning the system were generate. The quality assurance of relative and absolute dose distribution was carried out before clinical implementation. The salient features of Konrad planning s...

  2. Wide and stable optical frequency comb in an intensity-modulated continuous wave pumped optical fiber

    International Nuclear Information System (INIS)

    This paper investigates how to obtain a wide and stable optical frequency comb in an intensity-modulated continuous-wave pumped optical fiber by straightforwardly characterizing the signal-to-noise ratio and analyzing the optimal fiber length. The stability of the obtained optical frequency comb is analyzed by a method which is similar to the eye pattern. The prospect for obtaining wider and more stable optical frequency combs is discussed. (paper)

  3. Risk of second cancer from scattered radiation of intensity-modulated radiotherapies with lung cancer

    OpenAIRE

    Kim, Dong Wook; Chung, Weon Kuu; Shin, Dongoh; Hong, Seongeon; Park, Sung Ho; Park, Sung-Yong; Chung, Kwangzoo; Lim, Young Kyung; Shin, Dongho; Lee, Se Byeong; Lee, Hyun-ho; Yoon, Myonggeun

    2013-01-01

    Purpose To compare the risk of secondary cancer from scattered and leakage doses following intensity-modulated radiotherapy (IMRT), volumetric arc therapy (VMAT) and tomotherapy (TOMO) in patients with lung cancer. Methods IMRT, VMAT and TOMO were planned for five lung cancer patients. Organ equivalent doses (OEDs) are estimated from the measured corresponding secondary doses during irradiation at various points 20 to 80 cm from the iso-center by using radio-photoluminescence glass dosimeter ...

  4. Intensity modulated radiotherapy with concurrent chemotherapy for larynx preservation of advanced resectable hypopharyngeal cancer

    OpenAIRE

    Chao Hsing-Lung; Chang Ying-Nan; Lin Yaoh-Shiang; Lin Chun-Shu; Su Yu-Fu; Chen Chang-Ming; Jen Yee-Min; Huang Wen-Yen; Lin Kuen-Tze; Chang Li-Ping

    2010-01-01

    Abstract Background To analyze the rate of larynx preservation in patients of locally advanced hypopharyngeal cancer treated with intensity modulated radiotherapy (IMRT) plus concurrent chemotherapy, and compare the results with patients treated with primary surgery. Methods Between January 2003 and November 2007, 14 patients were treated with primary surgery and 33 patients were treated with concurrent chemoradiotherapy (CCRT) using IMRT technique. Survival rate, larynx preservation rate wer...

  5. Intensity-modulated stereotactic body radiotherapy for stage I non-small cell lung cancer

    OpenAIRE

    Kim, Min-Jeong; Yeo, Seung-Gu; KIM, EUN SEOK; MIN, CHUL KEE; SE AN, PYUNG

    2012-01-01

    This study aimed to investigate the clinical outcomes of intensity-modulated radiotherapy (IMRT)-based stereotactic body radiotherapy (SBRT) for patients with stage I non-small cell lung cancer (NSCLC). A prospective database of 16 consecutive patients receiving SBRT for pathologically-proven and peripherally-located stage I NSCLC was reviewed. Fifteen patients were medically inoperable and one patient refused to undergo surgery. The median age of the patients was 76 years (range, 69–86). Tre...

  6. Fatal pneumonitis associated with postoperative intensity-modulated radiotherapy in lung cancer: Case report and review

    OpenAIRE

    Hu, Yan; Li, Jingjing; SU, XIAOYAN

    2012-01-01

    Radiation pneumonitis (RP) is the most significant complication of acute treatment-related toxicities in lung cancer. Intensity-modulated radiotherapy (IMRT) with inverse planning enables us to achieve the desired dose distribution. However, there are many high-risk procedures associated with lung irradiation, including chemotherapy and surgery. We report a case of fatal treatment-related pneumonitis, where the patient had undergone postoperative IMRT for lung cancer. Following completion of ...

  7. The radiation techniques of tomotherapy & intensity-modulated radiation therapy applied to lung cancer

    OpenAIRE

    Zhu, Zhengfei; Fu, Xiaolong

    2015-01-01

    Radiotherapy (RT) plays an important role in the management of lung cancer. Development of radiation techniques is a possible way to improve the effect of RT by reducing toxicities through better sparing the surrounding normal tissues. This article will review the application of two forms of intensity-modulated radiation therapy (IMRT), fixed-field IMRT and helical tomotherapy (HT) in lung cancer, including dosimetric and clinical studies. The advantages and potential disadvantages of these t...

  8. Synchronous bilateral squamous cell carcinoma of the lung successfully treated using intensity-modulated radiotherapy

    OpenAIRE

    Loo, S W; Smith, S; Promnitz, D A; Van Tornout, F

    2012-01-01

    We present a case of synchronous bilateral inoperable lung cancer which required treatment with external beam radiotherapy to a radical dose. Intensity-modulated radiotherapy (IMRT) was used. More conformal dose distribution within the planning target volume was obtained using IMRT than the conventional technique. Dose–volume constraints defined for the lungs were met. Treatment was subsequently delivered using a seven-field IMRT plan. The patient remains alive and disease-free 48 months afte...

  9. Dosimetric absorption of intensity-modulated radiotherapy compared with conventional radiotherapy in breast-conserving surgery

    OpenAIRE

    Lin, Yang; WANG, BENZHONG

    2014-01-01

    The aim of this study was to investigate the dosimetric benefits between intensity-modulated radiotherapy (IMRT) and conventional radiotherapy (CR) among patients receiving breast-conserving surgery. A dosimetric comparison of IMRT and CR was evaluated in 20 patients with early-stage breast cancer using a three-dimensional treatment planning system. The prescribed mammary gland dose was completed in 25 fractions with a total dose of 5,000 cGy. Homogeneity of the planning target volume (PTV), ...

  10. Preliminary Treatment Results of Intensity-Modulated Radiotherapy for Prostate Cancer

    OpenAIRE

    Kang-Hsing Fan; Yen-Chao Chen; Cheng-Keng Chuang; Min-Li Hsieh; Ji-Hong Hong

    2006-01-01

    Background: To review the initial treatment results of intensity-modulated radiotherapy(IMRT) for prostate cancer.Methods: Ninety-two patients treated with IMRT before July 2003 were included inthis study. The median follow-up was 32 months. The indications for IMRTincluded primary, adjuvant, and salvage treatment. Combined treatment withandrogen suppression therapy was variable. The primary study endpointswere chronic adverse events which were subjectively reported. Only patientswith an aden...

  11. Evaluation of salivary function by sialoscintigraphy in locally advanced nasopharyngeal cancer patients after intensity modulated radiotherapy

    OpenAIRE

    T. L. Chuang; Y.F. Wang; C H Tsai; J E Chiu; Lee, M. S.; W Y Chiou; Lin, H Y; W T Tsai; S K Hung

    2015-01-01

    Purpose: This study aimed to evaluate the salivary gland function changes by sialoscintigraphy in locally advanced nasopharyngeal cancer (NPC) after intensity modulated radiotherapy (IMRT). Materials And Methods: Salivary function was assessed by sialoscintigraphy. Quantitative sialoscintigraphy was performed in 24 NPC patients prior to and after IMRT. Results were categorized in four groups according to the duration of treatment. The sialoscintigraphy parameters were examined. Results: Sialo...

  12. Accelerated Partial Breast Irradiation with Intensity-Modulated Radiotherapy Is Feasible for Chinese Breast Cancer Patients

    OpenAIRE

    He, Zhenyu; Wu, Sangang; Zhou, Juan; Li, Fengyan; Sun, Jiayan; Lin, Qin; Lin, Huanxin; Guan, Xunxing

    2014-01-01

    Purpose Several accelerated partial breast irradiation (APBI) techniques are being investigated in patients with early-stage breast cancer. The present study evaluated the feasibility, early toxicity, initial efficacy, and cosmetic outcomes of accelerated partial breast intensity-modulated radiotherapy (IMRT) for Chinese female patients with early-stage breast cancer after breast-conserving surgery. Methods A total of 38 patients met the inclusion criteria and an accelerated partial breast in...

  13. Prognostic value of wait time in nasopharyngeal carcinoma treated with intensity modulated radiotherapy: a propensitymatched analysis

    OpenAIRE

    Chen, Yu-Pei; Mao, Yan-Ping; Zhang, Wen-Na; Chen, Lei; Tang, Ling-Long; Li, Wen-Fei; Liu, Xu; Zhou, Guan-qun; Guo, Rui; Sun, Ying; Kang, Tie-Bang; Zeng, Mu-Sheng; Ma, Jun

    2016-01-01

    The aim of this study was to determine the prognostic value of wait time from histological diagnosis to primary treatmen for nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT). Between October 2009 and February 2012, a total of 1672 NPC patients were retrospectively analyzed. A cutoff value of > 4 weeks was used to define prolonged wait time. Matched patients according to the wait time were identified using propensity score matching (PSM), which was also used ...

  14. Adjuvant intensity-modulated proton therapy in malignant pleural mesothelioma. A comparison with intensity-modulated radiotherapy and a spot size variation assessment

    Energy Technology Data Exchange (ETDEWEB)

    Lorentini, S. [Agenzia Provinciale per la Protonterapia (ATreP), Trento (Italy); Padova Univ. (Italy). Medical Physics School; Amichetti, M.; Fellin, F.; Schwarz, M. [Agenzia Provinciale per la Protonterapia (ATreP), Trento (Italy); Spiazzi, L. [Brescia Hospital (Italy). Medical Physics Dept.; Tonoli, S.; Magrini, S.M. [Brescia Hospital (Italy). Radiation Oncology Dept.

    2012-03-15

    Intensity-modulated radiation therapy (IMRT) is the state-of-the-art treatment for patients with malignant pleural mesothelioma (MPM). The goal of this work was to assess whether intensity-modulated proton therapy (IMPT) could further improve the dosimetric results allowed by IMRT. We re-planned 7 MPM cases using both photons and protons, by carrying out IMRT and IMPT plans. For both techniques, conventional dose comparisons and normal tissue complication probability (NTCP) analysis were performed. In 3 cases, additional IMPT plans were generated with different beam dimensions. IMPT allowed a slight improvement in target coverage and clear advantages in dose conformity (p < 0.001) and dose homogeneity (p = 0.01). Better organ at risk (OAR) sparing was obtained with IMPT, in particular for the liver (D{sub mean} reduction of 9.5 Gy, p = 0.001) and ipsilateral kidney (V{sub 20} reduction of 58%, p = 0.001), together with a very large reduction of mean dose for the contralateral lung (0.2 Gy vs 6.1 Gy, p = 0.0001). NTCP values for the liver showed a systematic superiority of IMPT with respect to IMRT for both the esophagus (average NTCP 14% vs. 30.5%) and the ipsilateral kidney (p = 0.001). Concerning plans obtained with different spot dimensions, a slight loss of target coverage was observed along with sigma increase, while maintaining OAR irradiation always under planning constraints. Results suggest that IMPT allows better OAR sparing with respect to IMRT, mainly for the liver, ipsilateral kidney, and contralateral lung. The use of a spot dimension larger than 3 x 3 mm (up to 9 x 9 mm) does not compromise dosimetric results and allows a shorter delivery time.

  15. Dosimetric advantages of intensity-modulated proton therapy for oropharyngeal cancer compared with intensity-modulated radiation: A case-matched control analysis.

    Science.gov (United States)

    Holliday, Emma B; Kocak-Uzel, Esengul; Feng, Lei; Thaker, Nikhil G; Blanchard, Pierre; Rosenthal, David I; Gunn, G Brandon; Garden, Adam S; Frank, Steven J

    2016-01-01

    A potential advantage of intensity-modulated proton therapy (IMPT) over intensity-modulated (photon) radiation therapy (IMRT) in the treatment of oropharyngeal carcinoma (OPC) is lower radiation dose to several critical structures involved in the development of nausea and vomiting, mucositis, and dysphagia. The purpose of this study was to quantify doses to critical structures for patients with OPC treated with IMPT and compare those with doses on IMRT plans generated for the same patients and with a matched cohort of patients actually treated with IMRT. In this study, 25 patients newly diagnosed with OPC were treated with IMPT between 2011 and 2012. Comparison IMRT plans were generated for these patients and for additional IMRT-treated controls extracted from a database of patients with OPC treated between 2000 and 2009. Cases were matched based on the following criteria, in order: unilateral vs bilateral therapy, tonsil vs base of tongue primary, T-category, N-category, concurrent chemotherapy, induction chemotherapy, smoking status, sex, and age. Results showed that the mean doses to the anterior and posterior oral cavity, hard palate, larynx, mandible, and esophagus were significantly lower with IMPT than with IMRT comparison plans generated for the same cohort, as were doses to several central nervous system structures involved in the nausea and vomiting response. Similar differences were found when comparing dose to organs at risks (OARs) between the IMPT cohort and the case-matched IMRT cohort. In conclusion, these findings suggest that patients with OPC treated with IMPT may experience fewer and less severe side effects during therapy. This may be the result of decreased beam path toxicities with IMPT due to lower doses to several dysphagia, odynophagia, and nausea and vomiting-associated OARs. Further study is needed to evaluate differences in long-term disease control and chronic toxicity between patients with OPC treated with IMPT in comparison to those

  16. Whole abdomen radiation therapy in ovarian cancers: a comparison between fixed beam and volumetric arc based intensity modulation

    Directory of Open Access Journals (Sweden)

    Clivio Alessandro

    2010-11-01

    Full Text Available Abstract Purpose A study was performed to assess dosimetric characteristics of volumetric modulated arcs (RapidArc, RA and fixed field intensity modulated therapy (IMRT for Whole Abdomen Radiotherapy (WAR after ovarian cancer. Methods and Materials Plans for IMRT and RA were optimised for 5 patients prescribing 25 Gy to the whole abdomen (PTV_WAR and 45 Gy to the pelvis and pelvic nodes (PTV_Pelvis with Simultaneous Integrated Boost (SIB technique. Plans were investigated for 6 MV (RA6, IMRT6 and 15 MV (RA15, IMRT15 photons. Objectives were: for both PTVs V90% > 95%, for PTV_Pelvis: Dmax Results IMRT and RapidArc resulted comparable for target coverage. For PTV_WAR, V90% was 99.8 ± 0.2% and 93.4 ± 7.3% for IMRT6 and IMRT15, and 98.4 ± 1.7 and 98.6 ± 0.9% for RA6 and RA15. Target coverage resulted improved for PTV_Pelvis. Dose homogeneity resulted slightly improved by RA (Uniformity was defined as U5-95% = D5%-D95%/Dmean. U5-95% for PTV_WAR was 0.34 ± 0.05 and 0.32 ± 0.06 (IMRT6 and IMRT15, 0.30 ± 0.03 and 0.26 ± 0.04 (RA6 and RA15; for PTV_Pelvis, it resulted equal to 0.1 for all techniques. For organs at risk, small differences were observed between the techniques. MU resulted 3130 ± 221 (IMRT6, 2841 ± 318 (IMRT15, 538 ± 29 (RA6, 635 ± 139 (RA15; the average measured treatment time was 18.0 ± 0.8 and 17.4 ± 2.2 minutes (IMRT6 and IMRT15 and 4.8 ± 0.2 (RA6 and RA15. GAIIMRT6 = 97.3 ± 2.6%, GAIIMRT15 = 94.4 ± 2.1%, GAIRA6 = 98.7 ± 1.0% and GAIRA15 = 95.7 ± 3.7%. Conclusion RapidArc showed to be a solution to WAR treatments offering good dosimetric features with significant logistic improvements compared to IMRT.

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

    International Nuclear Information System (INIS)

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

  18. Whole abdomen radiation therapy in ovarian cancers: a comparison between fixed beam and volumetric arc based intensity modulation

    International Nuclear Information System (INIS)

    A study was performed to assess dosimetric characteristics of volumetric modulated arcs (RapidArc, RA) and fixed field intensity modulated therapy (IMRT) for Whole Abdomen Radiotherapy (WAR) after ovarian cancer. Plans for IMRT and RA were optimised for 5 patients prescribing 25 Gy to the whole abdomen (PTV-WAR) and 45 Gy to the pelvis and pelvic nodes (PTV-Pelvis) with Simultaneous Integrated Boost (SIB) technique. Plans were investigated for 6 MV (RA6, IMRT6) and 15 MV (RA15, IMRT15) photons. Objectives were: for both PTVs V90% > 95%, for PTV-Pelvis: Dmax < 105%; for organs at risk, maximal sparing was required. The MU and delivery time measured treatment efficiency. Pre-treatment Quality assurance was scored with Gamma Agreement Index (GAI) with 3% and 3 mm thresholds. IMRT and RapidArc resulted comparable for target coverage. For PTV-WAR, V90% was 99.8 ± 0.2% and 93.4 ± 7.3% for IMRT6 and IMRT15, and 98.4 ± 1.7 and 98.6 ± 0.9% for RA6 and RA15. Target coverage resulted improved for PTV-Pelvis. Dose homogeneity resulted slightly improved by RA (Uniformity was defined as U5-95% = D5%-D95%/Dmean). U5-95% for PTV-WAR was 0.34 ± 0.05 and 0.32 ± 0.06 (IMRT6 and IMRT15), 0.30 ± 0.03 and 0.26 ± 0.04 (RA6 and RA15); for PTV-Pelvis, it resulted equal to 0.1 for all techniques. For organs at risk, small differences were observed between the techniques. MU resulted 3130 ± 221 (IMRT6), 2841 ± 318 (IMRT15), 538 ± 29 (RA6), 635 ± 139 (RA15); the average measured treatment time was 18.0 ± 0.8 and 17.4 ± 2.2 minutes (IMRT6 and IMRT15) and 4.8 ± 0.2 (RA6 and RA15). GAIIMRT6 = 97.3 ± 2.6%, GAIIMRT15 = 94.4 ± 2.1%, GAIRA6 = 98.7 ± 1.0% and GAIRA15 = 95.7 ± 3.7%. RapidArc showed to be a solution to WAR treatments offering good dosimetric features with significant logistic improvements compared to IMRT

  19. Feasibility of a unified approach to intensity-modulated radiation therapy and volume-modulated arc therapy optimization and delivery

    International Nuclear Information System (INIS)

    Purpose: To study the feasibility of unified intensity-modulated arc therapy (UIMAT) which combines intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) optimization and delivery to produce superior radiation treatment plans, both in terms of dose distribution and efficiency of beam delivery when compared with either VMAT or IMRT alone. Methods: An inverse planning algorithm for UIMAT was prototyped within the PINNACLE treatment planning system (Philips Healthcare). The IMRT and VMAT deliveries are unified within the same arc, with IMRT being delivered at specific gantry angles within the arc. Optimized gantry angles for the IMRT and VMAT phases are assigned automatically by the inverse optimization algorithm. Optimization of the IMRT and VMAT phases is done simultaneously using a direct aperture optimization algorithm. Five treatment plans each for prostate, head and neck, and lung were generated using a unified optimization technique and compared with clinical IMRT or VMAT plans. Delivery verification was performed with an ArcCheck phantom (Sun Nuclear) on a Varian TrueBeam linear accelerator (Varian Medical Systems). Results: In this prototype implementation, the UIMAT plans offered the same target dose coverage while reducing mean doses to organs at risk by 8.4% for head-and-neck cases, 5.7% for lung cases, and 3.5% for prostate cases, compared with the VMAT or IMRT plans. In addition, UIMAT can be delivered with similar efficiency as VMAT. Conclusions: In this proof-of-concept work, a novel radiation therapy optimization and delivery technique that interlaces VMAT or IMRT delivery within the same arc has been demonstrated. Initial results show that unified VMAT/IMRT has the potential to be superior to either standard IMRT or VMAT

  20. Feasibility of a unified approach to intensity-modulated radiation therapy and volume-modulated arc therapy optimization and delivery

    Energy Technology Data Exchange (ETDEWEB)

    Hoover, Douglas A., E-mail: douglas.hoover@lhsc.on.ca; Chen, Jeff Z. [Department of Physics and Engineering, London Regional Cancer Program, London, Ontario N6A 4L6 (Canada); Department of Oncology, Western University, London, Ontario N6A 3K7 (Canada); Department of Medical Biophysics, Western University, London, Ontario N6A 3K7 (Canada); MacFarlane, Michael [Department of Physics and Engineering, London Regional Cancer Program, London, Ontario N6A 4L6 (Canada); Department of Medical Biophysics, Western University, London, Ontario N6A 3K7 (Canada); Wong, Eugene [Department of Oncology, Western University, London, Ontario N6A 3K7 (Canada); Department of Medical Biophysics, Western University, London, Ontario N6A 3K7 (Canada); Department of Physics and Astronomy, Western University, London, Ontario N6A 3K7 (Canada); Battista, Jerry J. [Department of Physics and Engineering, London Regional Cancer Program, London, Ontario N6A 4L6 (Canada); Department of Oncology, Western University, London, Ontario N6A 3K7 (Canada); Department of Medical Biophysics, Western University, London, Ontario N6A 3K7 (Canada); Department of Physics and Astronomy, Western University, London, Ontario N6A 3K7 (Canada)

    2015-02-15

    Purpose: To study the feasibility of unified intensity-modulated arc therapy (UIMAT) which combines intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) optimization and delivery to produce superior radiation treatment plans, both in terms of dose distribution and efficiency of beam delivery when compared with either VMAT or IMRT alone. Methods: An inverse planning algorithm for UIMAT was prototyped within the PINNACLE treatment planning system (Philips Healthcare). The IMRT and VMAT deliveries are unified within the same arc, with IMRT being delivered at specific gantry angles within the arc. Optimized gantry angles for the IMRT and VMAT phases are assigned automatically by the inverse optimization algorithm. Optimization of the IMRT and VMAT phases is done simultaneously using a direct aperture optimization algorithm. Five treatment plans each for prostate, head and neck, and lung were generated using a unified optimization technique and compared with clinical IMRT or VMAT plans. Delivery verification was performed with an ArcCheck phantom (Sun Nuclear) on a Varian TrueBeam linear accelerator (Varian Medical Systems). Results: In this prototype implementation, the UIMAT plans offered the same target dose coverage while reducing mean doses to organs at risk by 8.4% for head-and-neck cases, 5.7% for lung cases, and 3.5% for prostate cases, compared with the VMAT or IMRT plans. In addition, UIMAT can be delivered with similar efficiency as VMAT. Conclusions: In this proof-of-concept work, a novel radiation therapy optimization and delivery technique that interlaces VMAT or IMRT delivery within the same arc has been demonstrated. Initial results show that unified VMAT/IMRT has the potential to be superior to either standard IMRT or VMAT.

  1. Comparison of intensity modulated radiotherapy (IMRT) with intensity modulated particle therapy (IMPT) using fixed beams or an ion gantry for the treatment of patients with skull base meningiomas

    International Nuclear Information System (INIS)

    To examine the potential improvement in treatment planning for patients with skull base meningioma using IMRT compared to carbon ion or proton beams with and without a gantry. Five patients originally treated with photon IMRT were selected for the study. Ion beams were chosen using a horizontal beam or an ion gantry. Intensity controlled raster scanning and the intensity modulated particle therapy mode were used for plan optimization. The evaluation included analysis of dose-volume histograms of the target volumes and organs at risk. In comparison with carbon and proton beams only with horizontal beams, carbon ion treatment plans could spare the OARs more and concentrated on the target volumes more than proton and photon IMRT treatment plans. Using only a horizontal fixed beam, satisfactory plans could be achieved for skull base tumors. The results of the case studies showed that using IMPT has the potential to overcome the lack of a gantry for skull base tumors. Carbon ion plans offered slightly better dose distributions than proton plans, but the differences were not clinically significant with established dose prescription concepts

  2. An optimal algorithm for configuring delivery options of a one-dimensional intensity-modulated beam

    International Nuclear Information System (INIS)

    The problem of generating delivery options for one-dimensional intensity-modulated beams (1D IMBs) arises in intensity-modulated radiation therapy. In this paper, we present an algorithm with the optimal running time, based on the 'rightmost-preference' method, for generating all distinct delivery options for an arbitrary 1D IMB. The previously best known method for generating delivery options for a 1D IMB with N left leaf positions and N right leaf positions is a 'brute-force' solution, which first generates all N! possible combinations of the left and right leaf positions and then removes combinations that are not physically allowed delivery options. Compared with the brute-force method, our algorithm has several advantages: (1) our algorithm runs in an optimal time that is linearly proportional to the total number of distinct delivery options that it actually produces. Note that for a 1D IMB with multiple peaks, the total number of distinct delivery options in general tends to be considerably smaller than the worst case N!. (2) Our algorithm can be adapted to generating delivery options subject to additional constraints such as the 'minimum leaf separation' constraint. (3) Our algorithm can also be used to generate random subsets of delivery options; this feature is especially useful when the 1D IMBs in question have too many delivery options for a computer to store and process. The key idea of our method is that we impose an order on how left leaf positions should be paired with right leaf positions. Experiments indicated that our rightmost-preference algorithm runs dramatically faster than the brute-force algorithm. This implies that our algorithm can handle 1D IMBs whose sizes are substantially larger than those handled by the brute-force method. Applications of our algorithm in therapeutic techniques such as intensity-modulated arc therapy and 2D modulations are also discussed

  3. Intensity modulation with the 'step and shoot' technique using a commercial MLC

    International Nuclear Information System (INIS)

    Purpose/Objective: For complex planning situations where organs at risk surrounding the target volume place stringent constraints, intensity-modulated treatments with photons provide a promising solution to improve tumor control and/or to reduce side effects. In order to evaluate the feasibility to implement intensity-modulated treatment techniques in clinical practice, a phantom experiment is performed to investigate the whole chain from the treatment design by the inverse-planning method to the delivery of the intensity-modulated beams using a commercial, computer-controlled MLC. Materials and Methods: A typical, clinically relevant case of a patient with a head and neck tumor (clivus chordoma) is selected. Using the inverse planning technique, optimized treatment plans are generated for 5 and 9 evenly distributed coplanar beams. An iterative gradient method is used to optimize a physical objective function that is based on the specified target dose and individual dose constraints assigned to each organ at risk (brain stem, eyes, optic nerves) by the radiation oncologist. The resulting intensity distributions of each beam are converted into MLC leaf position sequences using the discrete 'step and shoot' method and the dynamic sweep method followed by a discretization of the trajectories. Regions of underdosage due to the stairstep or wave shape design of the leaves ('tongue and groove') are avoided through synchronization of neighboring leaf pairs. The algorithm at the same time eliminates collision problems due to the special hardware restriction of MLCs that forbid adjacent opposing leaves to pass each other. The MLC leaf position files are transferred via computer link from the planning system to the linac console. The intensity-modulated fields are delivered using the Siemens MLC integrated in a Mevatron KD2 accelerator. The sequences are executed in the discrete 'step and shoot' technique using the autosequence mode of the linac that allows to step through

  4. Adaptive illumination through spatial modulation of light intensity and image inversion

    International Nuclear Information System (INIS)

    The paper introduces the concept of spatial modulation of light intensity in the context of vision-based quality control, with the aim to improve image quality, measurable by indices such as image contrast and Tenengrad, so as to enhance the level of confidence of the diagnosis performed by image processing. The proposed technique is based on the projection of spatially modulated light intensity distribution by a digital light projector that allows an arbitrary light distribution to be projected on the target. The projected spatial distribution of light is determined by implementing an algorithm based on image inversion: the image acquired by the camera under uniform illumination is inverted and it is then used to modulate the light spatial distribution for projection. The process is repeated iteratively with the purpose to enhance image quality until convergence. The technique proves particularly valuable to avoid saturation from reflecting surfaces, which are often found in industrial practice. The procedure is tested and validated both by a numerical model and by an experimental validation, referring to a significant problem for the washing machine manufacturing industry. The use of image quality estimators confirms the effectiveness of the method. (paper)

  5. Linearization of an intensity-modulated analog photonic link using an FBG and a dispersive fiber

    Science.gov (United States)

    Gao, Yongsheng; Wen, Aijun; Chen, Yan; Zhang, Huixing; Xiang, Shuiying

    2015-03-01

    An optical linearization technique for an intensity-modulated analog photonic link is proposed and demonstrated. Conventional double-sideband intensity modulation is applied to modulate the radio frequency (RF) signal onto the optical carrier; then a fiber Bragg grating (FBG) is used to suppress part of the optical carrier and a single mode fiber (SMF) is followed to introduce some dispersion. By properly adjusting the dispersion-induced phase shift, the third-order intermodulation distortion can be suppressed. The proposed scheme is simple and low cost. The FBG can be also used to optimize the power ratio of the optical carrier and sidebands, thus improving the link gain, while the SMF can act as a transmission medium to deliver the RF signal. Experimental results show that an improvement of 12.6 dB in the spurious-free dynamic range and 3.8 dB in the link gain is achieved after linearization. The frequency tunability of the linearization technique is also evaluated by the transmission of RF signals with different center frequencies and bandwidths.

  6. Independent monitor unit calculation for intensity modulated radiotherapy using the MIMiC multileaf collimator

    International Nuclear Information System (INIS)

    A self-consistent monitor unit (MU) and isocenter point-dose calculation method has been developed that provides an independent verification of the MU for intensity modulated radiotherapy (IMRT) using the MIMiC (Nomos Corporation) multileaf collimator. The method takes into account two unique features of IMRT using the MIMiC: namely the gantry-dynamic arc delivery of intensity modulated photon beams and the slice-by-slice dose delivery for large tumor volumes. The method converts the nonuniform beam intensity planned at discrete gantry angles of 5 deg. or 10 deg. into conventional nonmodulated beam intensity apertures of elemental arc segments of 1 deg. This approach more closely simulates the actual gantry-dynamic arc delivery by MIMiC. Because each elemental arc segment is of uniform intensity, the MU calculation for an IMRT arc is made equivalent to a conventional arc with gantry-angle dependent beam apertures. The dose to the isocenter from each 1 deg. elemental arc segment is calculated by using the Clarkson scatter summation technique based on measured tissue-maximum-ratio and output factors, independent of the dose calculation model used in the IMRT planning system. For treatments requiring multiple treatment slices, the MU for the arc at each treatment slice takes into account the MU, leakage and scatter doses from other slices. This is achieved by solving a set of coupled linear equations for the MUs of all involved treatment slices. All input dosimetry data for the independent MU/isocenter point-dose calculation are measured directly. Comparison of the MU and isocenter point dose calculated by the independent program to those calculated by the Corvus planning system and to direct measurements has shown good agreement with relative difference less than ±3%. The program can be used as an independent initial MU verification for IMRT plans using the MIMiC multileaf collimators

  7. Binary Intensity Modulation and Hybrid Ternary Modulation Applied to Multiplexing Objects Using Holographic Data Storage on a PVA/AA Photopolymer

    OpenAIRE

    2014-01-01

    Holographic data pages were multiplexed in a polyvinyl alcohol/acrylamide photopolymer and a liquid crystal device was used to modify the object beam and store objects in the material. A peristrophic multiplexing method was used to store a large number of objects in the same spot of the material. The objects were stored using two different modulations: binary intensity modulation and hybrid ternary modulation. Moreover, the bit error rate (BER) of the images was calculated in order to compare...

  8. System design of programmable 4f phase modulation techniques for rapid intensity shaping: a conceptual comparison

    Science.gov (United States)

    Roth, Matthias; Heber, Jörg; Janschek, Klaus

    2016-03-01

    The present study analyses three beam shaping approaches with respect to a light-efficient generation of i) patterns and ii) multiple spots by means of a generic optical 4f-setup. 4f approaches share the property that due to the one-to-one relationship between output intensity and input phase, the need for time-consuming, iterative calculation can be avoided. The resulting low computational complexity offers a particular advantage compared to the widely used holographic principles and makes them potential candidates for real-time applications. The increasing availability of high-speed phase modulators, e.g. on the basis of MEMS, calls for an evaluation of the performances of these concepts. Our second interest is the applicability of 4f methods to high-power applications. We discuss the variants of 4f intensity shaping by phase modulation from a system-level point of view which requires the consideration of application relevant boundary conditions. The discussion includes i) the micro mirror based phase manipulation combined with amplitude masking in the Fourier plane, ii) the Generalized Phase Contrast, and iii) matched phase-only correlation filtering combined with GPC. The conceptual comparison relies on comparative figures of merit for energy efficiency, pattern homogeneity, pattern image quality, maximum output intensity and flexibility with respect to the displayable pattern. Numerical simulations illustrate our findings.

  9. Sampling considerations for intensity modulated radiotherapy verification using electronic portal imaging

    International Nuclear Information System (INIS)

    A model has been developed to describe the sampling process that occurs when intensity modulated radiotherapy treatments (delivered with a multileaf collimator) are imaged with an electronic portal imaging device that acquires a set of frames with a finite dead-time between them. The effects of the imaging duty cycle and frame rate on the accuracy of dosimetric verification have been studied. A frame interval of 1 s with 25%, 50% and 75% duty cycle, and a 50% duty cycle with frame intervals of 1, 2, 4, 8, and 16 s have been studied for a smoothly varying hemispherical intensity profile, and a 50% duty cycle with frame intervals of 1, 2, 4, and 8 s for a pixellated distribution. In addition an intensity modulated beam for breast radiotherapy has been modeled and imaged for 0.33 s frame time and 1, 2, and 3 s frame separation. The results show that under sparse temporal sampling conditions, errors of the order of 10% may ensue and occur with an oscillatory pattern. For the beams studied, imaging with a 1 or 2 s frame interval resulted in small errors at the 1%-2% level, for all duty cycles shown

  10. Dosimetric Comparison of Three-Dimensional Conformal Proton Radiotherapy, Intensity-Modulated Proton Therapy, and Intensity-Modulated Radiotherapy for Treatment of Pediatric Craniopharyngiomas

    International Nuclear Information System (INIS)

    Purpose: Cranial irradiation in pediatric patients is associated with serious long-term adverse effects. We sought to determine whether both three-dimensional conformal proton radiotherapy (3D-PRT) and intensity-modulated proton therapy (IMPT) compared with intensity-modulated radiotherapy (IMRT) decrease integral dose to brain areas known to harbor neuronal stem cells, major blood vessels, and other normal brain structures for pediatric patients with craniopharyngiomas. Methods and Materials: IMRT, forward planned, passive scattering proton, and IMPT plans were generated and optimized for 10 pediatric patients. The dose was 50.4 Gy (or cobalt Gy equivalent) delivered in 28 fractions with the requirement for planning target volume (PTV) coverage of 95% or better. Integral dose data were calculated from differential dose–volume histograms. Results: The PTV target coverage was adequate for all modalities. IMRT and IMPT yielded the most conformal plans in comparison to 3D-PRT. Compared with IMRT, 3D-PRT and IMPT plans had a relative reduction of integral dose to the hippocampus (3D-PRT, 20.4; IMPT, 51.3%∗), dentate gyrus (27.3, 75.0%∗), and subventricular zone (4.5, 57.8%∗). Vascular organs at risk also had reduced integral dose with the use of proton therapy (anterior cerebral arteries, 33.3∗, 100.0%∗; middle cerebral arteries, 25.9%∗, 100%∗; anterior communicating arteries, 30.8∗, 41.7%∗; and carotid arteries, 51.5∗, 77.6∗). Relative reduction of integral dose to the infratentorial brain (190.7∗, 109.7%∗), supratentorial brain without PTV (9.6, 26.8%∗), brainstem (45.6, 22.4%∗), and whole brain without PTV (19.4∗, 34.4%∗) were recorded with the use of proton therapy. (∗Differences were significant based on Friedman’s test with Bonferroni-Dunn correction, α = 0.05) Conclusions: The current study found that proton therapy was able to avoid excess integral radiation dose to a variety of normal structures at all dose levels while

  11. Plan comparison of volumetric-modulated arc therapy (RapidArc and conventional intensity-modulated radiation therapy (IMRT in anal canal cancer

    Directory of Open Access Journals (Sweden)

    Aillères Norbert

    2010-10-01

    Full Text Available Abstract Background To compare volumetric-modulated arc therapy (RapidArc plans with conventional intensity-modulated radiation therapy (IMRT plans in anal canal cancers. Methods Ten patients with anal canal carcinoma previously treated with IMRT in our institution were selected for this study. For each patient, three plans were generated with the planning CT scan: one using a fixed beam IMRT, and two plans using the RapidArc technique: a single (RA1 and a double (RA2 modulated arc therapy. The treatment plan was designed to deliver in one process with simultaneous integrated boost (SIB a dose of 59.4 Gy to the planning target volume (PTV2 based on the gross disease in a 1.8 Gy-daily fraction, 5 days a week. At the same time, the subclinical disease (PTV1 was planned to receive 49.5 Gy in a 1.5 Gy-daily fraction. Plans were normalized to 99% of the PTV2 that received 95% of the prescribed dose. Planning objectives were 95% of the PTV1 will receive 95% of the prescribed dose and no more than 2% of the PTV will receive more than 107%. Dose-volume histograms (DVH for the target volume and the organs at risk (bowel tract, bladder, iliac crests, femoral heads, genitalia/perineum, and healthy tissue were compared for these different techniques. Monitor units (MU and delivery treatment time were also reported. Results All plans achieved fulfilled objectives. Both IMRT and RA2 resulted in superior coverage of PTV than RA1 that was slightly inferior for conformity and homogeneity (p Conformity index (CI95% for the PTV2 was 1.15 ± 0.15 (RA2, 1.28 ± 0.22 (IMRT, and 1.79 ± 0.5 (RA1. Homogeneity (D5% - D95% for PTV2 was 3.21 ± 1.16 Gy (RA2, 2.98 ± 0.7 Gy (IMRT, and 4.3 ± 1.3 Gy (RA1. RapidArc showed to be superior to IMRT in terms of organ at risk sparing. For bowel tract, the mean dose was reduced of 4 Gy by RA2 compared to IMRT. Similar trends were observed for bladder, femoral heads, and genitalia. The DVH of iliac crests and healthy tissue resulted

  12. Plan comparison of volumetric-modulated arc therapy (RapidArc) and conventional intensity-modulated radiation therapy (IMRT) in anal canal cancer

    International Nuclear Information System (INIS)

    To compare volumetric-modulated arc therapy (RapidArc) plans with conventional intensity-modulated radiation therapy (IMRT) plans in anal canal cancers. Ten patients with anal canal carcinoma previously treated with IMRT in our institution were selected for this study. For each patient, three plans were generated with the planning CT scan: one using a fixed beam IMRT, and two plans using the RapidArc technique: a single (RA1) and a double (RA2) modulated arc therapy. The treatment plan was designed to deliver in one process with simultaneous integrated boost (SIB) a dose of 59.4 Gy to the planning target volume (PTV2) based on the gross disease in a 1.8 Gy-daily fraction, 5 days a week. At the same time, the subclinical disease (PTV1) was planned to receive 49.5 Gy in a 1.5 Gy-daily fraction. Plans were normalized to 99% of the PTV2 that received 95% of the prescribed dose. Planning objectives were 95% of the PTV1 will receive 95% of the prescribed dose and no more than 2% of the PTV will receive more than 107%. Dose-volume histograms (DVH) for the target volume and the organs at risk (bowel tract, bladder, iliac crests, femoral heads, genitalia/perineum, and healthy tissue) were compared for these different techniques. Monitor units (MU) and delivery treatment time were also reported. All plans achieved fulfilled objectives. Both IMRT and RA2 resulted in superior coverage of PTV than RA1 that was slightly inferior for conformity and homogeneity (p < 0.05). Conformity index (CI95%) for the PTV2 was 1.15 ± 0.15 (RA2), 1.28 ± 0.22 (IMRT), and 1.79 ± 0.5 (RA1). Homogeneity (D5% - D95%) for PTV2 was 3.21 ± 1.16 Gy (RA2), 2.98 ± 0.7 Gy (IMRT), and 4.3 ± 1.3 Gy (RA1). RapidArc showed to be superior to IMRT in terms of organ at risk sparing. For bowel tract, the mean dose was reduced of 4 Gy by RA2 compared to IMRT. Similar trends were observed for bladder, femoral heads, and genitalia. The DVH of iliac crests and healthy tissue resulted in comparable sparing for

  13. Volumetric Modulated Arc Therapy for Spine Radiosurgery: Superior Treatment Planning and Delivery Compared to Static Beam Intensity Modulated Radiotherapy

    Directory of Open Access Journals (Sweden)

    Leor Zach

    2016-01-01

    Full Text Available Purpose. Spine stereotactic radiosurgery (SRS delivers an accurate and efficient high radiation dose to vertebral metastases in 1–5 fractions. We aimed to compare volumetric modulated arc therapy (VMAT to static beam intensity modulated radiotherapy (IMRT for spine SRS. Methods and Materials. Ten spine lesions of previously treated SRS patients were planned retrospectively using both IMRT and VMAT with a prescribed dose of 16 Gy to 100% of the planning target volume (PTV. The plans were compared for conformity, homogeneity, treatment delivery time, and safety (spinal cord dose. Results. All evaluated parameters favored the VMAT plan over the IMRT plans. Dmin in the IMRT was significantly lower than in the VMAT plan (7.65 Gy/10.88 Gy, p<0.001, the Dice Similarity Coefficient (DSC was found to be significantly better for the VMAT plans compared to the IMRT plans (0.77/0.58, resp., p  value<0.01, and an almost 50% reduction in the net treatment time was calculated for the VMAT compared to the IMRT plans (6.73 min/12.96 min, p<0.001. Conclusions. In our report, VMAT provides better conformity, homogeneity, and safety profile. The shorter treatment time is a major advantage and not only provides convenience to the painful patient but also contributes to the precision of this high dose radiation therapy.

  14. The radiobiological effect of intra-fraction dose-rate modulation in intensity modulated radiation therapy (IMRT)

    Science.gov (United States)

    Bewes, J. M.; Suchowerska, N.; Jackson, M.; Zhang, M.; McKenzie, D. R.

    2008-07-01

    Intensity-modulated radiation therapy (IMRT) achieves optimal dose conformity to the tumor through the use of spatially and temporally modulated radiation fields. In particular, average dose rate and instantaneous dose rate (pulse amplitude) are highly variable within a single IMRT fraction. In this study we isolate these variables and determine their impact on cell survival. Survival was assessed using a clonogenic assay. Two cell lines of differing radiosensitivity were examined: melanoma (MM576) and non-small cell lung cancer (NCI-H460). The survival fraction was observed to be independent of instantaneous dose rate. A statistically significant trend to increased survival was observed as the average dose rate was decreased, for a constant total dose. The results are relevant to IMRT practice, where average treatment times can be significantly extended to allow for movement of the multi-leaf collimator (MLC). Our in vitro study adds to the pool of theoretical evidence for the consequences of protracted treatments. We find that extended delivery times can substantially increase the cell survival. This also suggests that regional variation in the dose-rate history across a tumor, which is inherent to IMRT, will affect radiation dose efficacy.

  15. Retrospective evaluation of dosimetric quality for prostate carcinomas treated with 3D conformal, intensity modulated and volumetric modulated arc radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, Scott B [Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland (Australia); Kairn, Tanya [Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland (Australia); Premion, Wesley Medical Centre, Brisbane, Queensland (Australia); Middlebrook, Nigel; Hill, Brendan; Christie, David R H; Knight, Richard T [Premion, Wesley Medical Centre, Brisbane, Queensland (Australia); Kenny, John [Australian Clinical Dosimetry Services, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Victoria (Australia); Langton, Christian M; Trapp, Jamie V [Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland (Australia)

    2013-12-15

    This study examines and compares the dosimetric quality of radiotherapy treatment plans for prostate carcinoma across a cohort of 163 patients treated across five centres: 83 treated with three-dimensional conformal radiotherapy (3DCRT), 33 treated with intensity modulated radiotherapy (IMRT) and 47 treated with volumetric modulated arc therapy (VMAT). Treatment plan quality was evaluated in terms of target dose homogeneity and organs at risk (OAR), through the use of a set of dose metrics. These included the mean, maximum and minimum doses; the homogeneity and conformity indices for the target volumes; and a selection of dose coverage values that were relevant to each OAR. Statistical significance was evaluated using two-tailed Welch's T-tests. The Monte Carlo DICOM ToolKit software was adapted to permit the evaluation of dose metrics from DICOM data exported from a commercial radiotherapy treatment planning system. The 3DCRT treatment plans offered greater planning target volume dose homogeneity than the other two treatment modalities. The IMRT and VMAT plans offered greater dose reduction in the OAR: with increased compliance with recommended OAR dose constraints, compared to conventional 3DCRT treatments. When compared to each other, IMRT and VMAT did not provide significantly different treatment plan quality for like-sized tumour volumes. This study indicates that IMRT and VMAT have provided similar dosimetric quality, which is superior to the dosimetric quality achieved with 3DCRT.

  16. Retrospective evaluation of dosimetric quality for prostate carcinomas treated with 3D conformal, intensity modulated and volumetric modulated arc radiotherapy

    International Nuclear Information System (INIS)

    This study examines and compares the dosimetric quality of radiotherapy treatment plans for prostate carcinoma across a cohort of 163 patients treated across five centres: 83 treated with three-dimensional conformal radiotherapy (3DCRT), 33 treated with intensity modulated radiotherapy (IMRT) and 47 treated with volumetric modulated arc therapy (VMAT). Treatment plan quality was evaluated in terms of target dose homogeneity and organs at risk (OAR), through the use of a set of dose metrics. These included the mean, maximum and minimum doses; the homogeneity and conformity indices for the target volumes; and a selection of dose coverage values that were relevant to each OAR. Statistical significance was evaluated using two-tailed Welch's T-tests. The Monte Carlo DICOM ToolKit software was adapted to permit the evaluation of dose metrics from DICOM data exported from a commercial radiotherapy treatment planning system. The 3DCRT treatment plans offered greater planning target volume dose homogeneity than the other two treatment modalities. The IMRT and VMAT plans offered greater dose reduction in the OAR: with increased compliance with recommended OAR dose constraints, compared to conventional 3DCRT treatments. When compared to each other, IMRT and VMAT did not provide significantly different treatment plan quality for like-sized tumour volumes. This study indicates that IMRT and VMAT have provided similar dosimetric quality, which is superior to the dosimetric quality achieved with 3DCRT

  17. Modulation instability of an intense laser beam in an unmagnetized electron–positron–ion plasma

    Indian Academy of Sciences (India)

    San Qiu Liu; Wei Tang; Xiao Qing Li

    2012-03-01

    The modulation instability of an intense circularly polarized laser beam propagating in an unmagnetized, cold electron–positron–ion plasma is investigated. Adopting a generalized Karpman method, a three-dimensional nonlinear equation is shown to govern the laser field. Then the conditions for modulation instability and the temporal growth rate are obtained analytically. In order to compare with the usual electron–ion plasmas, the effect of positron concentration is considered. It is found that the increase in positron-to-electron density ratio shifts the instability region towards higher vertical wave numbers but does not cause displacement along the parallel wave number direction, and the growth rate increases as the positron-to-electron density ratio increases.

  18. The principle and applications of an iso-energetic intensity modulation method for therapeutic electron beams

    International Nuclear Information System (INIS)

    Purpose/Objective: Many clinical situations indicate that an electron beam with a modified dose profile, i.e., tilted, concave or other shape is useful for the treatment with a curved, oblique or other non-flat skin surface. The well known difficulty in electron beam dose profile modification is the energy degradation while using absorbers with different thickness, such as wedge shape filter, similar to photon wedges. In this presentation, we describe the principle and applications of an iso-energetic electron beam intensity modulation method, a general technique which can be used to modified the intensity of a static electron field with virtually no alteration of the original beam energy. Materials and Methods: Due to the Coulomb multiple-scattering effect in air medium, Gaussian spread in air of the electron beam broadens with increasing distance from the source. Two narrow parallel electron beams with limited separation will join together as one composite distribution at certain distance from the source. Based on this physical principle, the intensity distribution of a broad electron beam can be modulated into different shapes by dividing the broad beam into a plurality of narrow slit electron beams with different spatial separation. With an adequate distance, these narrow electron beams merge to form a profile with desired shape and smoothness. Since an intensity modulated electron beam results from the plurality of narrow electron beams which have the same energy characteristics, the modulated beam will have the same energy as the original open beam. The applications of this new technique include the constructions of iso-energetic electron beam 'wedge' filters, concave filters (for dome shape skin surface such as skull), flattening filters for total skin treatment at an extended SSD, linac internal electron beam scattering/flattening filter, and other general electron beam compensating filters for irregular skin surface. Results: Several iso-energetic electron

  19. Local failure patterns for patients with nasopharyngeal carcinoma after intensity-modulated radiotherapy

    International Nuclear Information System (INIS)

    To investigate the clinical feature and the local failure patterns after intensity-modulated radiotherapy for nasopharyngeal carcinoma. Between March 2007 and July 2009, 710 patients with nasopharyngeal carcinoma were treated with intensity-modulated radiotherapy. The magnetic resonance imagings obtained at recurrence were registered with the original planning computed tomography for dosimetry analysis. With a median follow-up of 38 months, 34 patients have developed local recurrence (32 cases valid). The incidence of invasion to nasopharynx, parapharyngeal space and the retropharyngeal space by the primary tumors was 100%, 75.0% and 62.5%, respectively, but 78.1%, 34.4% and 21.9% at recurrence, respectively. The rate of invasion to ethmoid sinus was 3.1% by the primary tumors but 28.1% at recurrence (p = 0.005). The topographic analysis of the local failure patterns showed 'central' in 16 patients; 'marginal' in 9; and 'outside' in 7. The median volumes of primary gross tumor were 45.84 cm3 in the central failure group, 29.44 cm3 in the marginal failure group, and 21.52 cm3 in the outside failure group, respectively (p = 0.012), and the median volumes of primary clinical target1 were 87.28 cm3, 61.90 cm3 and 58.74 cm3 in the three groups, respectively (p = 0.033). In patients with nasopharyngeal carcinoma treated with intensity-modulated radiotherapy, the recurrent tumors had their unique characteristic and regularity of invasion to adjacent structures. 'Central' failure was the major local failure pattern. The volumes of primary gross tumor and clinical target1 were significantly correlated with recurrent patterns. Employ more aggressive approaches to tumor cells which will be insensitive to radiotherapy may be an effective way to reduce the central failure

  20. The use of intensity-modulated radiation therapy photon beams for improving the dose uniformity of electron beams shaped with MLC

    International Nuclear Information System (INIS)

    Electrons are ideal for treating shallow tumors and sparing adjacent normal tissue. Conventionally, electron beams are collimated by cut-outs that are time-consuming to make and difficult to adapt to tumor shape throughout the course of treatment. We propose that electron cut-outs can be replaced using photon multileaf collimator (MLC). Two major problems of this approach are that the scattering of electrons causes penumbra widening because of a large air gap, and available commercial treatment planning systems (TPSs) do not support MLC-collimated electron beams. In this study, these difficulties were overcome by (1) modeling electron beams collimated by photon MLC for a commercial TPS, and (2) developing a technique to reduce electron beam penumbra by adding low-energy intensity-modulated radiation therapy (IMRT) photons (4 MV). We used blocks to simulate MLC shielding in the TPS. Inverse planning was used to optimize boost photon beams. This technique was applied to a parotid and a central nervous system (CNS) clinical case. Combined photon and electron plans were compared with conventional plans and verified using ion chamber, film, and a 2D diode array. Our studies showed that the beam penumbra for mixed beams with 90 cm source to surface distance (SSD) is comparable with electron applicators and cut-outs at 100 cm SSD. Our mixed-beam technique yielded more uniform dose to the planning target volume and lower doses to various organs at risk for both parotid and CNS clinical cases. The plans were verified with measurements, with more than 95% points passing the gamma criteria of 5% in dose difference and 5 mm for distance to agreement. In conclusion, the study has demonstrated the feasibility and potential advantage of using photon MLC to collimate electron beams with boost photon IMRT fields.

  1. Intensity modulated radiotherapy as neoadjuvant chemoradiation for the treatment of patients with locally advanced pancreatic cancer. Outcome analysis and comparison with a 3D-treated patient cohort

    Energy Technology Data Exchange (ETDEWEB)

    Combs, S.E.; Habermehl, D.; Kessel, K.; Brecht, I. [Univ. Hospital of Heidelberg (Germany). Dept. of Radiation Oncology; Bergmann, F.; Schirmacher, P. [Univ. Hospital of Heidelberg (Germany). Dept. of Pathology; Werner, J.; Buechler, M.W. [Univ. Hospital of Heidelberg (Germany). Dept. of Surgery; Jaeger, D. [National Center for Tumor Diseases (NCT), Heidelberg (Germany); Debus, J. [Univ. Hospital of Heidelberg (Germany). Dept. of Radiation Oncology; Deutsches Krebsforschungszentrum (DKFZ), Heidelberg (Germany). Clinical Cooperation Unit Radiation Oncology

    2013-09-15

    Background: To evaluate outcome after intensity modulated radiotherapy (IMRT) compared to 3D conformal radiotherapy (3D-RT) as neoadjuvant treatment in patients with locally advanced pancreatic cancer (LAPC). Materials and methods: In total, 57 patients with LAPC were treated with IMRT and chemotherapy. A median total dose of 45 Gy to the PTV {sub baseplan} and 54 Gy to the PTV {sub boost} in single doses of 1.8 Gy for the PTV {sub baseplan} and median single doses of 2.2 Gy in the PTV {sub boost} were applied. Outcomes were evaluated and compared to a large cohort of patients treated with 3D-RT. Results: Overall treatment was well tolerated in all patients and IMRT could be completed without interruptions. Median overall survival was 11 months (range 5-37.5 months). Actuarial overall survival at 12 and 24 months was 36 % and 8 %, respectively. A significant impact on overall survival could only be observed for a decrease in CA 19-9 during treatment, patients with less pre-treatment CA 19-9 than the median, as well as weight loss during treatment. Local progression-free survival was 79 % after 6 months, 39 % after 12 months, and 13 % after 24 months. No factors significantly influencing local progression-free survival could be identified. There was no difference in overall and progression-free survival between 3D-RT and IMRT. Secondary resectability was similar in both groups (26 % vs. 28 %). Toxicity was comparable and consisted mainly of hematological toxicity due to chemotherapy. Conclusion: IMRT leads to a comparable outcome compared to 3D-RT in patients with LAPC. In the future, the improved dose distribution, as well as advances in image-guided radiotherapy (IGRT) techniques, may improve the use of IMRT in local dose escalation strategies to potentially improve outcome. (orig.)

  2. Optimal beam arrangement for pulmonary ventilation image-guided intensity-modulated radiotherapy for lung cancer

    OpenAIRE

    Wang, Ruihao; Zhang, Shuxu; YU, HUI; Lin, Shengqu; Zhang, Guoqian; Tang, Rijie; Qi, Bin

    2014-01-01

    Background The principal aim of this study was to evaluate the feasibility of incorporating four-dimensional (4D)-computed tomography (CT)-based functional information into treatment planning and to evaluate the potential benefits of individualized beam setups to better protect lung functionality in patients with non-small cell lung cancer (NSCLC). Methods Peak-exhale and peak-inhale CT scans were carried out in 16 patients with NSCLC treated with intensity-modulated radiotherapy (IMRT). 4D-C...

  3. Combining discrete cosine transform with clipping for PAPR reduction in intensity-modulated OFDM systems

    Science.gov (United States)

    Wang, Zhong-peng; Chen, Shou-fa; Zhou, Yang; Chen, Ming; Tang, Jin; Chen, Lin

    2014-09-01

    In this paper, the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signal is reduced by combining the discrete cosine transform (DCT) with clipping in optical intensity-modulated direct-detection (IM/DD) OFDM systems. First, the data are transformed into new modified data by DCT. Second, the proposed scheme utilizes the clipping technique to further reduce the PAPR of OFDM signal. We experimentally demonstrate that the optical OFDM transmission system with this proposed scheme can achieve significant performance improvement in terms of PAPR and bit error rate (BER) compared with the original optical OFDM systems.

  4. A light intensity measuring system for sedimentation measurements on KM3NeT optical modules

    International Nuclear Information System (INIS)

    To measure variations of zenith dependence of sedimentation/bio-fouling on the optical modules (OMs) as considered by the KM3NeT consortium in the deep sea, we have used a grid of photodiodes distributed inside the glass sphere to measure the light intensity of two light sources located outside the glass sphere on a fixed position. The method is described and the data collected during the last three years in depths from 3100 m down to 5100 m, in the southeast Ionian sea, at sites near Pylos, Peloponnese, Greece, are discussed.

  5. A light intensity measuring system for sedimentation measurements on KM3NeT optical modules

    Energy Technology Data Exchange (ETDEWEB)

    Anassontzis, E.G. [Physics Department, University of Athens (Greece); Belias, A., E-mail: belias@nestor.org.g [NESTOR Institute for Astroparticle Physics, National Observatory of Athens, 24001 Pylos (Greece); Fotiou, A.; Koutsoukos, S.; Markopoulos, E.; Psallidas, A. [NESTOR Institute for Astroparticle Physics, National Observatory of Athens, 24001 Pylos (Greece); Resvanis, L.K. [Physics Department, University of Athens (Greece); NESTOR Institute for Astroparticle Physics, National Observatory of Athens, 24001 Pylos (Greece); Stavropoulos, G. [NESTOR Institute for Astroparticle Physics, National Observatory of Athens, 24001 Pylos (Greece)

    2011-01-21

    To measure variations of zenith dependence of sedimentation/bio-fouling on the optical modules (OMs) as considered by the KM3NeT consortium in the deep sea, we have used a grid of photodiodes distributed inside the glass sphere to measure the light intensity of two light sources located outside the glass sphere on a fixed position. The method is described and the data collected during the last three years in depths from 3100 m down to 5100 m, in the southeast Ionian sea, at sites near Pylos, Peloponnese, Greece, are discussed.

  6. Dosimetric Studies of Mixed Energy Intensity Modulated Radiation Therapy for Prostate Cancer Treatments

    OpenAIRE

    Abdul Haneefa, K.; K. K. Shakir; Siddhartha, A.; T. Siji Cyriac; Musthafa, M. M.; R. Ganapthi Raman

    2014-01-01

    Dosimetric studies of mixed field photon beam intensity modulated radiation therapy (IMRT) for prostate cancer using pencil beam (PB) and collapsed cone convolution (CCC) algorithms using Oncentra MasterPlan treatment planning system (v. 4.3) are investigated in this study. Three different plans were generated using 6 MV, 15 MV, and mixed beam (both 6 and 15 MV). Fifteen patients with two sets of plans were generated: one by using PB and the other by using CCC for the same planning parameters...

  7. The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer

    OpenAIRE

    Sung, Wonmo; Park, Jong Min; Choi, Chang Heon; Ha, Sung Whan; Ye, Sung-Joon

    2012-01-01

    Purpose To evaluate the effect of common three photon energies (6-MV, 10-MV, and 15-MV) on intensity-modulated radiation therapy (IMRT) plans to treat prostate cancer patients. Materials and Methods Twenty patients with prostate cancer treated locally to 81.0 Gy were retrospectively studied. 6-MV, 10-MV, and 15-MV IMRT plans for each patient were generated using suitable planning objectives, dose constraints, and 8-field setting. The plans were analyzed in terms of dose-volume histogram for t...

  8. Approximated segmentation considering technical and dosimetric constraints in intensity-modulated radiation therapy with electrons

    CERN Document Server

    Kiesel, Antje

    2010-01-01

    In intensity-modulated radiation therapy, optimal intensity distributions of incoming beams are decomposed into linear combinations of leaf openings of a multileaf collimator (segments). In order to avoid inefficient dose delivery, the decomposition should satisfy a number of dosimetric constraints due to suboptimal dose characteristics of small segments. However, exact decomposition with dosimetric constraints is only in limited cases possible. The present work introduces new heuristic segmentation algorithms for the following optimization problem: Find a segmentation of an approximated matrix using only allowed fields and minimize the approximation error. Finally, the decomposition algorithms were implemented into an optimization programme in order to examine the assumptions of the algorithms for a clinical example. As a result, identical dose distributions with much fewer segments and a significantly smaller number of monitor units could be achieved using dosimetric constraints. Consequently, the dose deli...

  9. Dosimetric and QA aspects of Konrad inverse planning system for commissioning intensity-modulated radiation therapy.

    Science.gov (United States)

    Deshpande, Shrikant; Sathiyanarayanan, V K; Bhangle, Janhavi; Swamy, Kumara; Basu, Sumit

    2007-04-01

    The intensity-modulated radiation therapy (IMRT) planning is performed using the Konrad inverse treatment planning system and the delivery of the treatment by using Siemens Oncor Impression Plus linear accelerator (step and shoot), which has been commissioned recently. The basic beam data required for commissioning the system were generate. The quality assurance of relative and absolute dose distribution was carried out before clinical implementation. The salient features of Konrad planning system, like dependence of grid size on dose volume histogram (DVH), number of intensity levels and step size in sequencer, are studied quantitatively and qualitatively.To verify whether the planned dose [from treatment planning system (TPS)] and delivered dose are the same, the absolute dose at a point is determined using CC01 ion chamber and the axial plane dose distribution is carried out using Kodak EDR2 in conjunction with OmniPro IMRT Phantom and OmniPro IMRT software from Scanditronix Wellhofer. To obtain the optimum combination in leaf sequencer module, parameters like number of intensity levels, step size are analyzed. The difference between pixel values of optimum fluence profile and the fluence profile obtained for various combinations of number of intensity levels and step size is compared and plotted. The calculations of the volume of any RT structure in the dose volume histogram are compared using grid sizes 3 mm and 4 mm. The measured and planned dose at a point showed good agreement (chamber was placed in a relatively high dose gradient region. The axial plane dose distribution using film dosimetry shows excellent agreement (correlation coefficient >0.97) in all the cases. In the leaf sequencer module, the combination of number of intensity level 7 with step size of 3 is the optimal solution for obtaining deliverable segments. The RT structure volume calculation is found to be more accurate with grid size of 3 mm for clinical use.Thus a study regarding various

  10. Dosimetric and QA aspects of Konrad inverse planning system for commissioning intensity-modulated radiation therapy

    Directory of Open Access Journals (Sweden)

    Deshpande Shrikant

    2007-01-01

    Full Text Available The intensity-modulated radiation therapy (IMRT planning is performed using the Konrad inverse treatment planning system and the delivery of the treatment by using Siemens Oncor Impression Plus linear accelerator (step and shoot, which has been commissioned recently. The basic beam data required for commissioning the system were generate. The quality assurance of relative and absolute dose distribution was carried out before clinical implementation. The salient features of Konrad planning system, like dependence of grid size on dose volume histogram (DVH, number of intensity levels and step size in sequencer, are studied quantitatively and qualitatively. To verify whether the planned dose [from treatment planning system (TPS] and delivered dose are the same, the absolute dose at a point is determined using CC01 ion chamber and the axial plane dose distribution is carried out using Kodak EDR2 in conjunction with OmniPro IMRT Phantom and OmniPro IMRT software from Scanditronix Wellhofer. To obtain the optimum combination in leaf sequencer module, parameters like number of intensity levels, step size are analyzed. The difference between pixel values of optimum fluence profile and the fluence profile obtained for various combinations of number of intensity levels and step size is compared and plotted. The calculations of the volume of any RT structure in the dose volume histogram are compared using grid sizes 3 mm and 4 mm. The measured and planned dose at a point showed good agreement (< 3% except for a few cases wherein the chamber was placed in a relatively high dose gradient region. The axial plane dose distribution using film dosimetry shows excellent agreement (correlation coefficient> 0.97 in all the cases. In the leaf sequencer module, the combination of number of intensity level 7 with step size of 3 is the optimal solution for obtaining deliverable segments. The RT structure volume calculation is found to be more accurate with grid size of

  11. Comparison of three concomitant boost techniques for early-stage breast cancer

    International Nuclear Information System (INIS)

    Purpose: Whole breast radiotherapy (RT) followed by a tumor bed boost typically spans 5-6 weeks of treatment. Interest is growing in RT regimens, such as concomitant boost, that decrease overall treatment time, lessening the time/cost burden to patients and facilities. Methods and Materials: Computed tomography (CT) scans from 20 cases were selected for this retrospective, dosimetric study to compare three different techniques of concomitant boost delivery: (1) standard tangents plus an electron boost (2) intensity-modulated RT (IMRT) tangents using custom compensators plus an electron boost, and (3) IMRT tangents plus a conformal photon boost. The equivalent uniform dose model was used to compare the plans. Results: The average breast equivalent uniform dose value for the three techniques (standard, IMRT plus electrons, and IMRT plus photons) was 48.6, 47.9, and 48.3, respectively. The plans using IMRT more closely approximated the prescribed dose of 46 Gy to the whole breast. The breast volume receiving >110% of the dose was less with the IMRT tangents than with standard RT (p 0.037), but no significant difference in the maximal dose or other evaluated parameters was noted. Conclusion: Although the IMRT techniques delivered the prescribed dose with better dose uniformity, the small improvement seen did not support a goal of improved resource use

  12. Beam intensity modulation for penumbra enhancement and field length reduction in lung cancer treatments: a dosimetric study

    International Nuclear Information System (INIS)

    In a recent treatment planning study, a previously published technique for superior-inferior field length reduction for prostate cancer patients, based on penumbra enhancement using static beam intensity modulation (BIM) with a multileaf collimator, was investigated for lung cancer treatments. For the patient group studied, the field lengths could be reduced by 1.4 cm and an average dose escalation of 6 Gy (maximum 16 Gy) appeared to be possible without any increase in the calculated risk of radiation pneumonitis. However, this planning study was performed with a treatment planning system that does not correctly account for the increased lateral secondary electron transport in lung tissue, resulting in too steep beam penumbrae. Therefore, prior to clinical implementation, an extensive dosimetric study was performed to evaluate and optimize BIM for penumbra enhancement and superior-inferior field length reduction in lung cancer treatments. Film dosimetry was performed in several phantoms consisting of water equivalent and lung equivalent materials, both for a 6 and a 10 MV photon beam. Measured dose distributions were used to (i) adapt the BIM technique to properly account for increased lateral secondary electron transport, (ii) compare BIM dose distributions in lung material with dose distributions of standard treatment fields, and (iii) investigate the use of our treatment planning system for the design of BIM plans for lung cancer patients. Compared with our treatment planning study the superior and inferior boost fields, used in the BIM technique for penumbra enhancement, had to be longer and of a higher weight to compensate for the increased lateral secondary electron transport in lung tissue. With these modifications in the BIM technique, field lengths could indeed be reduced by 1.4 cm compared with treatment with standard fields, without the appearance of underdosages in the most superior and inferior target areas, whilst better sparing the healthy lung

  13. Advanced intensity-modulation continuous-wave lidar techniques for ASCENDS CO2 column measurements

    Science.gov (United States)

    Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.; Harrison, F. W.; Obland, Michael D.; Meadows, Byron

    2015-10-01

    Global atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity- Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space to meet the ASCENDS measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) modulation technique to uniquely discriminate surface lidar returns from intermediate aerosol and cloud contamination. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby eliminating the need to correct for sidelobe bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. This approach works well for both BPSK and linear swept-frequency modulation techniques. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. A comparison of BPSK and linear swept-frequency is also discussed in this paper. These results are extended to include Richardson-Lucy deconvolution techniques to extend the resolution of the lidar beyond that implied by limit of the bandwidth of the modulation, where it is shown useful for making tree canopy measurements.

  14. SCALING OF X-RAY-DIFFRACTION INTENSITIES FOR CRYSTALS WITH A ONE-DIMENSIONAL, INCOMMENSURATE, DISPLACIVE MODULATION

    NARCIS (Netherlands)

    LAM, EJW; BEURSKENS, PT; VANSMAALEN, S

    1992-01-01

    A statistical method is presented for the determination of the scale factor, an overall isotropic temperature factor and an overall modulation amplitude from the X-ray diffraction intensities of crystals with a one-dimensional, incommensurate, displacive modulation. Application to several compounds

  15. Binary Intensity Modulation and Hybrid Ternary Modulation Applied to Multiplexing Objects Using Holographic Data Storage on a PVA/AA Photopolymer

    Directory of Open Access Journals (Sweden)

    Elena Fernandez

    2014-01-01

    Full Text Available Holographic data pages were multiplexed in a polyvinyl alcohol/acrylamide photopolymer and a liquid crystal device was used to modify the object beam and store objects in the material. A peristrophic multiplexing method was used to store a large number of objects in the same spot of the material. The objects were stored using two different modulations: binary intensity modulation and hybrid ternary modulation. Moreover, the bit error rate (BER of the images was calculated in order to compare which modulation is most appropriate to be used for holographic data storage.

  16. Intensity modulated radiotherapy (IMRT) combined with concurrent but not adjuvant chemotherapy in primary nasopharyngeal cancer – a retrospective single center analysis

    International Nuclear Information System (INIS)

    We report our experience in 49 consecutive patients with nasopharyngeal carcinoma who were treated by Intensity-modulated radiation therapy (IMRT) combined with simultaneous but not adjuvant chemotherapy (CHT). The medical records of 49 patients with histologically proven primary nasopharygeal carcinoma treated with IMRT and concurrent platin-based CHT (predominantly cisplatin weekly) were retrospectively reviewed. The majority of patients showed advanced clinical stages (stage III/IV:72%) with undifferentiated histology (82%). IMRT was performed in step-and-shoot technique using an integrated boost concept in 84%. In this concept, the boost volume covered the primary tumor and involved nodes with doses of 66–70.4 Gy (single dose 2.2 Gy). Uninvolved regional nodal areas were covered with doses of 54–59.4 Gy (median single dose 1.8 Gy). At least one parotid gland was spared. None of the patients received adjuvant CHT. The median follow-up for the entire cohort was 48 months. Radiation therapy was completed without interruption in all patients and 76% of the patients received at least 80% of the scheduled CHT. Four local recurrences have been observed, transferring into 1-, 3-, and 5-year Local Control (LC) rates of 98%, 90% and 90%. One patient developed an isolated regional nodal recurrence, resulting in 1-, 3-, and 5-year Regional Control (RC) rates of 98%. All locoregional failures were located inside the radiation fields. Distant metastases were found in six patients, transferring into 1-, 3, and 5-year Distant Control (DC) rates of 92%, 86% and 86%. Progression free survival (PFS) rates after 1, 3 and 5 years were 86%, 70% and 69% and 1-, 3- and 5-year Overall Survival (OS) rates were 96%, 82% and 79%. Acute toxicity ≥ grade III mainly consisted of dysphagia (32%), leukopenia (24%), stomatitis (16%), infection (8%) and nausea (8%). Severe late toxicity (grade III) was documented in 18% of the patients, mainly as xerostomia (10%). Concurrent chemoradiation

  17. Intensity-modulated radiotherapy for pituitary adenomas: The preliminary report of Cleveland Clinic experience

    International Nuclear Information System (INIS)

    Purpose: Intensity-modulated radiotherapy (IMRT) is being increasingly used for the treatment of pituitary adenomas. However, there have been few published data on the short- and long-term outcomes of this treatment. This is the initial report of Cleveland Clinic's experience. Methods and Materials: Between February 1998 and December 2003, 34 patients with pituitary adenomas were treated with IMRT. A retrospective chart review was conducted for data analysis. Results: With a median follow-up of 42.5 months, the treatment has proven to be well tolerated, with performance status remaining stable in 90% of patients. Radiographic local control was 89%, and among patients with secretory tumors, 100% had a biochemical response. Only 1 patient required salvage surgery for progressive disease, giving a clinical progression free survival of 97%. The only patient who received more than 46 Gy experienced optic neuropathy 8 months after radiation. Smaller tumor volume significantly correlated with subjective improvements in nonvisual neurologic complaints (p = 0.03), and larger tumor volume significantly correlated with subjective worsening of visual symptoms (p = 0.05). New hormonal supplementation was required for 40% of patients. Younger patients were significantly more likely to require hormonal supplementation (p 0.03). Conclusions: Intensity-modulated radiation therapy is a safe and effective treatment for pituitary adenomas over the short term. Longer follow-up is necessary to determine if IMRT confers any advantage with respect to either tumor control or toxicity over conventional radiation modalities

  18. Volumetric intensity modulated arc therapy in lung cancer: Current literature review

    Directory of Open Access Journals (Sweden)

    Suresh B Rana

    2013-01-01

    Full Text Available The volumetric intensity modulated arc therapy (VMAT is a novel radiation technique that delivers a highly conformal radiation dose to the target by allowing the simultaneous variation of gantry rotation speed, dose rate and multiple-leaf collimators leaf positions. The aim of this study was to review the current literature on two VMAT systems, RapidArc and SmartArc with main focus on planning studies of lung cancer. A systematic review of available data was conducted using MEDLINE/PubMed with the keywords ′′lung′′ and "VMAT". The published data show that VMAT techniques have clear superiority over three-dimensional conformal radiation therapy with regard to improving dose conformity and sparing of organs at risks (OARs. The data indicates that for lung tumor VMAT and intensity modulated radiation therapy (IMRT provide equivalent dose homogeneity, dose conformity and target volume coverage; however, contradictory results were obtained in terms of OARs sparing. The major advantages of VMAT over IMRT are the reduction in the number of monitor units and faster treatment delivery times without compromising the quality of the treatment plans. Moreover, faster delivery time is more patient-friendly and it minimizes intra-fractional patient motion allowing treatment volumes stay within their respective treatment margins. Current literature data shows that VMAT can be a good option to treat lung cancer; however, data on clinical trials are still lacking. The clinical trials are essential to confirm the safety and efficacy of VMAT techniques.

  19. Optimization of intensity modulated radiotherapy under constraints for static and dynamic MLC delivery

    International Nuclear Information System (INIS)

    Multi-leaf collimators (MLCs) are emerging as the prevalent modality to apply intensity modulated radiotherapy (IMRT). Both the principle and the particular design of MLCs stipulate complex constraints on the practically applicable intensity modulated radiation fields. Most consequentially, the distribution of exposure times across the maximum field outline is either a piecewise constant function in the static mode or a piecewise linear function in the dynamic mode of driving an MLC. In view of clinical utility, the total leaf movement should be minimized, which requires that MLC-related constraints be considered in the dose optimization process. A method is proposed to achieve this for both static MLC fields and dynamic leaf close-in application. The method is an amendment to a generic gradient-based IMRT dose optimization algorithm and solves numerical problems related to the non-convexity of the MLC constraints, which can cause erratic behaviour of a gradient-based algorithm. It employs bistable penalty functions to select preferable leaf configurations from the configuration space of the MLC, which is limited by specific design features. Together with an 'annealing' escape mechanism from local minima, the algorithm is capable of finding the optimum of an IMRT problem as leaf sequences with minimized leaf travel. In particular, the efficiency of static IMRT can be raised to the levels of unmodulated fields with very few field segments, thereby increasing the utility of IMRT in clinical practice. (author)

  20. Predictors for Clinical Outcomes After Accelerated Partial Breast Intensity-Modulated Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To correlate the treatment planning parameters with the clinical outcomes in patients treated with accelerated partial breast intensity-modulated radiotherapy. Methods and Materials: A total of 105 patients with Stage I breast cancer were treated between February 2004 and March 2007 in a Phase II prospective trial and had detailed information available on the planning target volume (PTV), ipsilateral breast volume (IBV), PTV/IBV ratio, lung volume, chest wall volume, surgery to radiotherapy interval, follow-up interval, breast pain, and cosmesis. The first 7 of these patients were treated to 34 Gy, and the remaining 98 were treated to 38.5 Gy. All patients were treated twice daily for 5 consecutive days. Univariate and multivariate analyses were performed. Results: The median follow-up was 13 months. No recurrences or deaths were observed. Of the 105 patients, 30 reported mild or moderate breast pain in their most recently recorded follow-up visit. The irradiated lung volume (p 35 Gy (p 35 Gy) and to lung correlated with reports of mild pain after accelerated partial breast intensity-modulated radiotherapy. Also, the PTV, but not the PTV/IBV ratio, was predictive of post-treatment reports of pain.

  1. Intensity-Modulated Radiotherapy for Sinonasal Cancer: Improved Outcome Compared to Conventional Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To evaluate clinical outcome and toxicity of postoperative intensity-modulated radiotherapy (IMRT) for malignancies of the nasal cavity and paranasal sinuses. Methods and Materials: Between 2003 and 2008, 40 patients with cancer of the paranasal sinuses (n = 34) or nasal cavity (n = 6) received postoperative IMRT to a dose of 60 Gy (n = 21) or 66 Gy (n = 19). Treatment outcome and toxicity were retrospectively compared with that of a previous patient group (n = 41) who were also postoperatively treated to the same doses but with three-dimensional conformal radiotherapy without intensity modulation, from 1992 to 2002. Results: Median follow-up was 30 months (range, 4-74 months). Two-year local control, overall survival, and disease-free survival were 76%, 89%, and 72%, respectively. Compared to the three-dimensional conformal radiotherapy treatment, IMRT resulted in significantly improved disease-free survival (60% vs. 72%; p = 0.02). No grade 3 or 4 toxicity was reported in the IMRT group, either acute or chronic. The use of IMRT significantly reduced the incidence of acute as well as late side effects, especially regarding skin toxicity, mucositis, xerostomia, and dry-eye syndrome. Conclusions: Postoperative IMRT for sinonasal cancer significantly improves disease-free survival and reduces acute as well as late toxicity. Consequently, IMRT should be considered the standard treatment modality for malignancies of the nasal cavity and paranasal sinuses.

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

    OpenAIRE

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

    2013-01-01

    The purpose of the study was to determine the dosimetric difference between three emerging treatment modalities—volumetric-modulated arc therapy (VMAT), intensity-modulated proton beam therapy (IMPT) and intensity-modulated carbon ion beam therapy (IMIT)—for two tumour sites where selective boosting of the tumour is applied. For 10 patients with locally advanced head and neck (H&N) cancer and 10 with high-risk prostate cancer (PC) a VMAT plan was generated for PTVinitial that included lymph n...

  3. Genetic algorithm based deliverable segments optimization for static intensity-modulated radiotherapy

    International Nuclear Information System (INIS)

    The static delivery technique (also called step-and-shoot technique) has been widely used in intensity-modulated radiotherapy (IMRT) because of the simple delivery and easy quality assurance. Conventional static IMRT consists of two steps: first to calculate the intensity-modulated beam profiles using an inverse planning algorithm, and then to translate these profiles into a series of uniform segments using a leaf-sequencing tool. In order to simplify the procedure and shorten the treatment time of the static mode, an efficient technique, called genetic algorithm based deliverable segments optimization (GADSO), is developed in our work, which combines these two steps into one. Taking the pre-defined beams and the total number of segments per treatment as input, the number of segments for each beam, the segment shapes and weights are determined automatically. A group of interim modulated beam profiles quickly calculated using a conjugate gradient (CG) method are used to determine the segment number for each beam and to initialize segment shapes. A modified genetic algorithm based on a two-dimensional binary coding scheme is used to optimize the segment shapes, and a CG method is used to optimize the segment weights. The physical characters of a multileaf collimator, such as the leaves interdigitation limitation and leaves maximum over-travel distance, are incorporated into the optimization. The algorithm is applied to some examples and the results demonstrate that GADSO is able to produce highly conformal dose distributions using 20-30 deliverable segments per treatment within a clinically acceptable computation time

  4. Two-step intensity modulated arc therapy (2-step IMAT) with segment weight and width optimization

    International Nuclear Information System (INIS)

    2-step intensity modulated arc therapy (IMAT) is a simplified IMAT technique which delivers the treatment over typically two continuous gantry rotations. The aim of this work was to implement the technique into a computerized treatment planning system and to develop an approach to optimize the segment weights and widths. 2-step IMAT was implemented into the Prism treatment planning system. A graphical user interface was developed to generate the plan segments automatically based on the anatomy in the beam's-eye-view. The segment weights and widths of 2-step IMAT plans were subsequently determined in Matlab using a dose-volume based optimization process. The implementation was tested on a geometric phantom with a horseshoe shaped target volume and then applied to a clinical paraspinal tumour case. The phantom study verified the correctness of the implementation and showed a considerable improvement over a non-modulated arc. Further improvements in the target dose uniformity after the optimization of 2-step IMAT plans were observed for both the phantom and clinical cases. For the clinical case, optimizing the segment weights and widths reduced the maximum dose from 114% of the prescribed dose to 107% and increased the minimum dose from 87% to 97%. This resulted in an improvement in the homogeneity index of the target dose for the clinical case from 1.31 to 1.11. Additionally, the high dose volume V105 was reduced from 57% to 7% while the maximum dose in the organ-at-risk was decreased by 2%. The intuitive and automatic planning process implemented in this study increases the prospect of the practical use of 2-step IMAT. This work has shown that 2-step IMAT is a viable technique able to achieve highly conformal plans for concave target volumes with the optimization of the segment weights and widths. Future work will include planning comparisons of the 2-step IMAT implementation with fixed gantry intensity modulated radiotherapy (IMRT) and commercial IMAT

  5. Whole-brain hippocampal sparing radiation therapy: Volume-modulated arc therapy vs intensity-modulated radiation therapy case study.

    Science.gov (United States)

    Lee, Katrina; Lenards, Nishele; Holson, Janice

    2016-01-01

    The hippocampus is responsible for memory and cognitive function. An ongoing phase II clinical trial suggests that sparing dose to the hippocampus during whole-brain radiation therapy can help preserve a patient׳s neurocognitive function. Progressive research and advancements in treatment techniques have made treatment planning more sophisticated but beneficial for patients undergoing treatment. The aim of this study is to evaluate and compare hippocampal sparing whole-brain (HS-WB) radiation therapy treatment planning techniques using volume-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT). We randomly selected 3 patients to compare different treatment techniques that could be used for reducing dose to the hippocampal region. We created 2 treatment plans, a VMAT and an IMRT, from each patient׳s data set and planned on the Eclipse 11.0 treatment planning system (TPS). A total of 6 plans (3 IMRT and 3 VMAT) were created and evaluated for this case study. The physician contoured the hippocampus as per the Radiation Therapy Oncology Group (RTOG) 0933 protocol atlas. The organs at risk (OR) were contoured and evaluated for the plan comparison, which included the spinal cord, optic chiasm, the right and left eyes, lenses, and optic nerves. Both treatment plans produced adequate coverage on the planning target volume (PTV) while significantly reducing dose to the hippocampal region. The VMAT treatment plans produced a more homogenous dose distribution throughout the PTV while decreasing the maximum point dose to the target. However, both treatment techniques demonstrated hippocampal sparing when irradiating the whole brain. PMID:26235550

  6. Comparative analysis of volumetric-modulated arc therapy and intensity-modulated radiotherapy for base of tongue cancer

    Directory of Open Access Journals (Sweden)

    L Nithya

    2014-01-01

    Full Text Available The aim of this study was to compare the various dosimetric parameters of dynamic multileaf collimator (MLC intensity modulated radiation therapy (IMRT plans with volumetric modulated arc therapy (VMAT plans for base of tongue cases. All plans were done in Monaco planning system for Elekta synergy linear accelerator with 80 MLC. IMRT plans were planned with nine stationary beams, and VMAT plans were done for 360° arc with single arc or dual arc. The dose to the planning target volumes (PTV for 70, 63, and 56 Gy was compared. The dose to 95, 98, and 50% volume of PTV were analyzed. The homogeneity index (HI and the conformity index (CI of the PTV 70 were also analyzed. IMRT and VMAT plan showed similar dose coverage, HI, and CI. Maximum dose and dose to 1-cc volume of spinal cord, planning risk volume (PRV cord, and brain stem were compared. IMRT plan and VMAT plan showed similar results except for the 1 cc of PRV cord that received slightly higher dose in VMAT plan. Mean dose and dose to 50% volume of right and left parotid glands were analyzed. VMAT plan gave better sparing of parotid glands than IMRT. In normal tissue dose analyses VMAT was better than IMRT. The number of monitor units (MU required for delivering the good quality of the plan and the time required to deliver the plan for IMRT and VMAT were compared. The number of MUs for VMAT was higher than that of IMRT plans. However, the delivery time was reduced by a factor of two for VMAT compared with IMRT. VMAT plans yielded good quality of the plan compared with IMRT, resulting in reduced treatment time and improved efficiency for base of tongue cases.

  7. Cardiac Exposure in the Dynamic Conformal Arc Therapy, Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy of Lung Cancer.

    Directory of Open Access Journals (Sweden)

    Xin Ming

    Full Text Available To retrospectively evaluate the cardiac exposure in three cohorts of lung cancer patients treated with dynamic conformal arc therapy (DCAT, intensity-modulated radiotherapy (IMRT, or volumetric modulated arc therapy (VMAT at our institution in the past seven years.A total of 140 lung cancer patients were included in this institutional review board approved study: 25 treated with DCAT, 70 with IMRT and 45 with VMAT. All plans were generated in a same commercial treatment planning system and have been clinically accepted and delivered. The dose distribution to the heart and the effects of tumor laterality, the irradiated heart volume and the beam-to-heart distance on the cardiac exposure were investigated.The mean dose to the heart among all 140 plans was 4.5 Gy. Specifically, the heart received on average 2.3, 5.2 and 4.6 Gy in the DCAT, IMRT and VMAT plans, respectively. The mean heart doses for the left and right lung tumors were 4.1 and 4.8 Gy, respectively. No patients died with evidence of cardiac disease. Three patients (2% with preexisting cardiac condition developed cardiac disease after treatment. Furthermore, the cardiac exposure was found to increase linearly with the irradiated heart volume while decreasing exponentially with the beam-to-heart distance.Compared to old technologies for lung cancer treatment, modern radiotherapy treatment modalities demonstrated better heart sparing. But the heart dose in lung cancer radiotherapy is still higher than that in the radiotherapy of breast cancer and Hodgkin's disease where cardiac complications have been extensively studied. With strong correlations of mean heart dose with beam-to-heart distance and irradiated heart volume, cautions should be exercised to avoid long-term cardiac toxicity in the lung cancer patients undergoing radiotherapy.

  8. Volumetric-Modulated Arc Therapy for Stereotactic Body Radiotherapy of Lung Tumors: A Comparison With Intensity-Modulated Radiotherapy Techniques

    International Nuclear Information System (INIS)

    Purpose: To demonstrate the potential of volumetric-modulated arc therapy (VMAT) compared with intensity-modulated radiotherapy (IMRT) techniques with a limited number of segments for stereotactic body radiotherapy (SBRT) for early-stage lung cancer. Methods and Materials: For a random selection of 27 patients eligible for SBRT, coplanar and noncoplanar IMRT and coplanar VMAT (using SmartArc) treatment plans were generated in Pinnacle3 and compared. In addition, film measurements were performed using an anthropomorphic phantom to evaluate the skin dose for the different treatment techniques. Results: Using VMAT, the delivery times could be reduced to an average of 6.6 min compared with 23.7 min with noncoplanar IMRT. The mean dose to the healthy lung was 4.1 Gy for VMAT and noncoplanar IMRT and 4.2 Gy for coplanar IMRT. The volume of healthy lung receiving >5 Gy and >20 Gy was 18.0% and 5.4% for VMAT, 18.5% and 5.0% for noncoplanar IMRT, and 19.4% and 5.7% for coplanar IMRT, respectively. The dose conformity at 100% and 50% of the prescribed dose of 54 Gy was 1.13 and 5.17 for VMAT, 1.11 and 4.80 for noncoplanar IMRT and 1.12 and 5.31 for coplanar IMRT, respectively. The measured skin doses were comparable for VMAT and noncoplanar IMRT and slightly greater for coplanar IMRT. Conclusions: Coplanar VMAT for SBRT for early-stage lung cancer achieved plan quality and skin dose levels comparable to those using noncoplanar IMRT and slightly better than those with coplanar IMRT. In addition, the delivery time could be reduced by ≤70% with VMAT.

  9. SU-E-J-70: Evaluation of Multiple Isocentric Intensity Modulated and Volumetric Modulated Arc Therapy Techniques Using Portal Dosimetry

    International Nuclear Information System (INIS)

    Purpose: To develop a method for verification of dose distribution in a patient during treatment using multiple isocentric Intensity modulated and volumetric modulated arc therapy techniques with portal dosimetry. Methods: Varian True Beam accelerator, equipped with an aS1000 megavoltage electronic portal imaging device (EPID) has an integrated image mode for portal dosimetry (PD). The source-to-imager distance was taken at 150 cm to avoid collision to the table. Fourteen fractions were analyzed for this study. During shift in a single plan from one isocenter to another isocenter, EPID also shifted longitudinally for each field by taking the extent of divergence of beam into the consideration for EPID distance of 150cm. Patients were given treatment everyday with EPID placed in proper position for each field. Several parameters were obtained by comparing the dose distribution between fractions to fraction. The impact of the intra-fraction and inter-fraction of the patient in combination with isocenter shift of the beams were observed. Results: During treatment, measurements were performed by EPID and were evaluated by the gamma method. Analysis was done between fractions for multiple isocenter treatments. The pass rates of the gamma analysis with a criterion of 3% and 3 mm for the 14 fractions were over 97.8% with good consistency. Whereas maximum gamma exceeded the criteria in few fractions (in<1 cc vol). Average gamma was observed in the criteria of 0.5%. Maximum dose difference and average dose differences were less than 0.22 CU and 0.01 CU for maximum tolerance of 1.0 CU and 0.2 CU respectively. Conclusion: EPID with extended distance is ideal method to verify the multiple isocentric dose distribution in patient during treatment, especially cold and hot spots in junction dose. Verification of shifts as well as the dose differences between each fraction due to inter-fraction and intra-fraction of the patient can be derived

  10. Dosimetric comparison of volumetric modulated Arc therapy with conventional intensity-modulated radiotherapy for preoperative radiotherapy of rectal cancer

    International Nuclear Information System (INIS)

    Objective: To compare the dosimetric difference between RapidArc and fixed gantry angle dynamic intensity modulated radiotherapy (dIMRT) in developing the pre-operative radiotherapy for rectal cancer patients. Methods: Two techniques, RapidArc and dIMRT, were used respectively to develop the synchronous intensity modulated plans for 10 stage Ⅱ and Ⅲ rectal cancer patients at the dose of gross tumor volume (GTV) of 50.6 Gy divided into 22 fractions and planning target volume (PTV) of 41.8 Gy divided into 22 fractions. Both plans satisfied the condition of 95% of PTV covered by 41.8 Gy. The dose-volume histogram data, isodose distribution, monitor units, and treatment time were compared. Results: The two kinds of dose volume histogram (DVH) developed by these two techniques were almost the same. The conformal indexes of GTV and PTV by RapidArc were better than those by dIMRT (t=7.643, 8.226, P<0.05), while the homogeneity of target volume by dIMRT was better (t=-10.065, -4.235, P<0.05). The dose of rectum and small bowel planned by RapidArc was significantly lower than that by dIMRT (t=2.781, P<0.05). There were no significant differences in the mean doses of bladder and femoral head between these two techniques. The mean monitor units of RapidArc was 475.5, fewer by 48.5% in comparison with that by the dIMRT (924.6). The treatment mean time by RapidArc was 1.2 min, shorter by 79.5% in comparison with that by dIMRT (5.58 min). Conclusions: There is no significant dosimetric difference between the two plans of RapidArc and dIMRT. Compared with dIMRT, RapidArc achieves equal target coverage and organs at risk (OAR) sparing while using fewer monitor units and less time during radiotherapy for patient with rectal cancer. (authors)

  11. Clinical Realization of Sector Beam Intensity Modulation for Gamma Knife Radiosurgery: A Pilot Treatment Planning Study

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Lijun, E-mail: lijunma@radonc.ucsf.edu [Department of Radiation Oncology, University of California, San Francisco, California (United States); Mason, Erica; Sneed, Penny K.; McDermott, Michael; Polishchuk, Alexei; Larson, David A. [Department of Radiation Oncology, University of California, San Francisco, California (United States); Sahgal, Arjun [Department of Radiation Oncology, Sunnybrook Odette Cancer Center, University of Toronto, Toronto, Ontario (Canada)

    2015-03-01

    Purpose: To demonstrate the clinical feasibility and potential benefits of sector beam intensity modulation (SBIM) specific to Gamma Knife stereotactic radiosurgery (GKSRS). Methods and Materials: SBIM is based on modulating the confocal beam intensities from individual sectors surrounding an isocenter in a nearly 2π geometry. This is in contrast to conventional GKSRS delivery, in which the beam intensities from each sector are restricted to be either 0% or 100% and must be identical for any given isocenter. We developed a SBIM solution based on available clinical planning tools, and we tested it on a cohort of 12 clinical cases as a proof of concept study. The SBIM treatment plans were compared with the original clinically delivered treatment plans to determine dosimetric differences. The goal was to investigate whether SBIM would improve the dose conformity for these treatment plans without prohibitively lengthening the treatment time. Results: A SBIM technique was developed. On average, SBIM improved the Paddick conformity index (PCI) versus the clinically delivered plans (clinical plan PCI = 0.68 ± 0.11 vs SBIM plan PCI = 0.74 ± 0.10, P=.002; 2-tailed paired t test). The SBIM plans also resulted in nearly identical target volume coverage (mean, 97 ± 2%), total beam-on times (clinical plan 58.4 ± 38.9 minutes vs SBIM 63.5 ± 44.7 minutes, P=.057), and gradient indices (clinical plan 3.03 ± 0.27 vs SBIM 3.06 ± 0.29, P=.44) versus the original clinical plans. Conclusion: The SBIM method is clinically feasible with potential dosimetric gains when compared with conventional GKSRS.

  12. Inversely planned intensity modulated radiotheraphy for irradiation of a woman with breast cancer and funnel chest

    International Nuclear Information System (INIS)

    Background: A 44-year old woman with breast cancer was transferred to our institution for irradiation. Due to a pronounced funnel chest no satisfying dose distribution was obtained by conventional techniques. Thus an intensity-modulated radiotherapy (IMRT) based on inverse optimisation was carried out. IMRT was compared to conventional techniques regarding dose distribution and feasibility. Patient and Methods: Tumor site was in the right middle lower quadrant. Target volume included the right breast and the parasternal lymph nodes. Target dose was 50.4 Gy. Based on inverse optimisation irradiation was carried out in 'step-and-short'-technique with twelve intensity modulated beams with six intensity steps. Additionally, treatment plans were calculated using conventional techniques (technique A with two tangential wedged 6-MV photon beams, technique B with additional oblique 15-MeV electron portal). We analysed conformality and homogeneity of target volume and dose distribution within normal tissue. Results: Dose conformality was substantially improved by IMRT. Dose homogeneity was slightly decreased compared to technique A. Lung volume irradiated with a dose higher than 20 Gy was reduced from 56.8% with technique A and 40.1% with technique B, respectively to 22.1% with IMRT. Treatment was tolerated well by the patient without relevant side effects. Mean treatment time was 19.5 min. Conclusion: The inversely planned IMRT using multiple beam directions is suitable for breast irradiation following breast conserving surgery. In the present case of a woman with funnel chest lung dose was substantially reduced without reduction of target dose. In which way the complex treatment technique leads to a clinically detectable advantage is examined at present, in the context of a study. (orig.)

  13. Volumetric intensity-modulated Arc (RapidArc therapy for primary hepatocellular carcinoma: comparison with intensity-modulated radiotherapy and 3-D conformal radiotherapy

    Directory of Open Access Journals (Sweden)

    Chen Chia-Wen

    2011-06-01

    Full Text Available Abstract Background To compare the RapidArc plan for primary hepatocellular carcinoma (HCC with 3-D conformal radiotherapy (3DCRT and intensity-modulated radiotherapy (IMRT plans using dosimetric analysis. Methods Nine patients with unresectable HCC were enrolled in this study. Dosimetric values for RapidArc, IMRT, and 3DCRT were calculated for total doses of 45~50.4 Gy using 1.8 Gy/day. The parameters included the conformal index (CI, homogeneity index (HI, and hot spot (V107% for the planned target volume (PTV as well as the monitor units (MUs for plan efficiency, the mean dose (Dmean for the organs at risk (OAR and the maximal dose at 1% volume (D1% for the spinal cord. The percentage of the normal liver volume receiving ≥ 40, > 30, > 20, and > 10 Gy (V40 Gy, V30 Gy, V20 Gy, and V10 Gy and the normal tissue complication probability (NTCP were also evaluated to determine liver toxicity. Results All three methods achieved comparable homogeneity for the PTV. RapidArc achieved significantly better CI and V107% values than IMRT or 3DCRT (p p mean of the normal liver than did 3DCRT or RapidArc (p = 0.001. 3DCRT had higher V40 Gy and V30 Gy values for the normal liver than did RapidArc or IMRT. Although the V10 Gy to the normal liver was higher with RapidArc (75.8 ± 13.1% than with 3DCRT or IMRT (60.5 ± 10.2% and 57.2 ± 10.0%, respectively; p p = 0.02. Conclusions RapidArc provided favorable tumor coverage compared with IMRT or 3DCRT, but RapidArc is not superior to IMRT in terms of liver protection. Further studies are needed to establish treatment outcome differences between the three approaches.

  14. Progress on the 140 KV, 10 Megawatt Peak, 1 Megawatt Average Polyphase Quasi-Resonant Bridge, Boost Converter/Modulator for the Spallation Neutron Source (SNS) Klystron Power System

    OpenAIRE

    Reass, William A.; Doss, James D.; Gribble, Robert F.; Lynch, Michael T.; Tallerico, Paul J.

    2000-01-01

    This paper describes electrical design and operational characteristics of a zero-voltage-switching 20 kHz polyphase bridge, boost converter/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three "H-Bridge" IGBT switching networks are used to generate the polyphase 20 kHz transform...

  15. Hippocampal - brainstem connectivity associated with vagal modulation after an intense exercise intervention in healthy men

    Directory of Open Access Journals (Sweden)

    Karl Juergen Bär

    2016-04-01

    Full Text Available AbstractRegular physical exercise leads increased vagal modulation of the cardiovascular system. A combination of peripheral and central processes has been proposed to underlie this adaptation. However, specific changes in the central autonomic network have not been described in human in more detail. We hypothesized that the anterior hippocampus known to be influenced by regular physical activity might be involved in the development of increased vagal modulation after a 6 weeks high intensity intervention in young healthy men (exercise group: n=17, control group: n=17. In addition to the determination of physical capacity before and after the intervention, we used resting state functional magnetic resonance imaging and synchronic heart rate variability assessment.We detected a significant increase of the power output at the anaerobic threshold of 11.4% (p<0.001, the maximum power output Pmax of 11.2% (p<0.001, and VO2max adjusted for body weight of 4.7% (p<0.001 in the exercise group (EG. Comparing baseline (T0 and post-exercise (T1 values of parasympathetic modulation of the exercise group, we observed a trend for a decrease in heart rate (p<0.06 and a significant increase of vagal modulation as indicated by RMSSD (p<0.026 during resting state. In the whole brain analysis, we found that the connectivity pattern of the right anterior hippocampus (aHC was specifically altered to the ventromedial anterior cortex, the dorsal striatum and to the dorsal vagal complex (DVC in the brainstem. Moreover, we only observed a highly significant negative correlation between increased RMSSD after exercise and decreased functional connectivity from the right aHC to DVC (r=-0.69, p=0.003. This indicates that increased vagal modulation was associated with functional connectivity between aHC and the dorsal vagal complex.In conclusion, our findings suggest that exercise associated changes in anterior hippocampal function might be involved in increased vagal

  16. Interfractional Dose Variations in Intensity-Modulated Radiotherapy With Breath-Hold for Pancreatic Cancer

    International Nuclear Information System (INIS)

    Purpose: To investigate the interfractional dose variations for intensity-modulated radiotherapy (RT) combined with breath-hold (BH) at end-exhalation (EE) for pancreatic cancer. Methods and Materials: A total of 10 consecutive patients with pancreatic cancer were enrolled. Each patient was fixed in the supine position on an individualized vacuum pillow with both arms raised. Computed tomography (CT) scans were performed before RT, and three additional scans were performed during the course of chemoradiotherapy using a conventional RT technique. The CT data were acquired under EE–BH conditions (BH–CT) using a visual feedback technique. The intensity-modulated RT plan, which used five 15-MV coplanar ports, was designed on the initial BH–CT set with a prescription dose of 39 Gy at 2.6 Gy/fraction. After rigid image registration between the initial and subsequent BH–CT scans, the dose distributions were recalculated on the subsequent BH–CT images under the same conditions as in planning. Changes in the dose–volume metrics of the gross tumor volume (GTV), clinical target volume (CTV = GTV + 5 mm), stomach, and duodenum were evaluated. Results: For the GTV and clinical target volume (CTV), the 95th percentile of the interfractional variations in the maximal dose, mean dose, dose covering 95% volume of the region of structure, and percentage of the volume covered by the 90% isodose line were within ±3%. Although the volume covered by the 39 Gy isodose line for the stomach and duodenum did not exceed 0.1 mL at planning, the volume covered by the 39 Gy isodose line for these structures was up to 11.4 cm3 and 1.8 cm3, respectively. Conclusions: Despite variations in the gastrointestinal state and abdominal wall position at EE, the GTV and CTV were mostly ensured at the planned dose, with the exception of 1 patient. Compared with the duodenum, large variations in the stomach volume receiving high-dose radiation were observed, which might be beyond the negligible

  17. Dose to Larynx Predicts for Swallowing Complications After Intensity-Modulated Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To evaluate early swallowing after intensity-modulated radiotherapy for head and neck squamous cell carcinoma and determine factors correlating with aspiration and/or stricture. Methods and Materials: Consecutive patients treated with intensity-modulated radiotherapy with or without chemotherapy between September 2004 and August 2006 at the Dana Farber Cancer Institute/Brigham and Women's Hospital were evaluated with institutional review board approval. Patients underwent swallowing evaluation after completion of therapy; including video swallow studies. The clinical- and treatment-related variables were examined for correlation with aspiration or strictures, as well as doses to the larynx, pharyngeal constrictor muscles, and cervical esophagus. The correlation was assessed with logistic regression analysis. Results: A total of 96 patients were evaluated. Their median age was 55 years, and 79 (82%) were men. The primary site of cancer was the oropharynx in 43, hypopharynx/larynx in 17, oral cavity in 13, nasopharynx in 11, maxillary sinus in 2, and unknown primary in 10. Of the 96 patients, 85% underwent definitive RT and 15% postoperative RT. Also, 28 patients underwent induction chemotherapy followed by concurrent chemotherapy, 59 received concurrent chemotherapy, and 9 patients underwent RT alone. The median follow-up was 10 months. Of the 96 patients, 31 (32%) had clinically significant aspiration and 36 (37%) developed a stricture. The radiation dose-volume metrics, including the volume of the larynx receiving ≥50 Gy (p = 0.04 and p = 0.03, respectively) and volume of the inferior constrictor receiving ≥50 Gy (p = 0.05 and p = 0.02, respectively) were significantly associated with both aspiration and stricture. The mean larynx dose correlated with aspiration (p = 0.003). Smoking history was the only clinical factor to correlate with stricture (p = 0.05) but not aspiration. Conclusion: Aspiration and stricture are common side effects after

  18. Interfractional Dose Variations in Intensity-Modulated Radiotherapy With Breath-Hold for Pancreatic Cancer

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-04-01

    Purpose: To investigate the interfractional dose variations for intensity-modulated radiotherapy (RT) combined with breath-hold (BH) at end-exhalation (EE) for pancreatic cancer. Methods and Materials: A total of 10 consecutive patients with pancreatic cancer were enrolled. Each patient was fixed in the supine position on an individualized vacuum pillow with both arms raised. Computed tomography (CT) scans were performed before RT, and three additional scans were performed during the course of chemoradiotherapy using a conventional RT technique. The CT data were acquired under EE-BH conditions (BH-CT) using a visual feedback technique. The intensity-modulated RT plan, which used five 15-MV coplanar ports, was designed on the initial BH-CT set with a prescription dose of 39 Gy at 2.6 Gy/fraction. After rigid image registration between the initial and subsequent BH-CT scans, the dose distributions were recalculated on the subsequent BH-CT images under the same conditions as in planning. Changes in the dose-volume metrics of the gross tumor volume (GTV), clinical target volume (CTV = GTV + 5 mm), stomach, and duodenum were evaluated. Results: For the GTV and clinical target volume (CTV), the 95th percentile of the interfractional variations in the maximal dose, mean dose, dose covering 95% volume of the region of structure, and percentage of the volume covered by the 90% isodose line were within {+-}3%. Although the volume covered by the 39 Gy isodose line for the stomach and duodenum did not exceed 0.1 mL at planning, the volume covered by the 39 Gy isodose line for these structures was up to 11.4 cm{sup 3} and 1.8 cm{sup 3}, respectively. Conclusions: Despite variations in the gastrointestinal state and abdominal wall position at EE, the GTV and CTV were mostly ensured at the planned dose, with the exception of 1 patient. Compared with the duodenum, large variations in the stomach volume receiving high-dose radiation were observed, which might be beyond the

  19. Intensity modulated radiation therapy (IMRT) for sinonasal tumors: a single center long-term clinical analysis

    International Nuclear Information System (INIS)

    Radiotherapy has a central role in the treatment of sinonasal malignancies, either as postoperative or as primary therapy. To study the efficacy and safety of intensity modulated radiotherapy (IMRT) for sinonasal tumors a single center retrospective evaluation focusing on survival and therapy related toxicity was performed. One hundred twenty two patients with primary (n = 82) or recurrent (n = 40) malignant sinonasal tumors were treated with intensity modulated radiotherapy between 1999 and 2009 at the University Clinic of Heidelberg and the German Cancer Research Center and retrospectively analyzed. Most patients had adenoid cystic carcinomas (n = 47) or squamous cell carcinoma (n = 26). 99 patients received postoperative radiotherapy. The median total dose was 64 Gy in conventional fractionation (1.8–2 Gy). Overall survival (OS), progression free survival (PFS) and local recurrence free survival (LRFS) rates were calculated using the Kaplan-Meier method. The log-rank test and Fishers Exact test were applied for univariate analysis, Cox-regression was used for multivariate analysis. Median follow up was 36 months. 1-, 3- and 5-year estimated overall survival rates were 90, 70 and 54 % respectively. Median progression free survival and local recurrence free survival was 45 and 63 months respectively. Progression free survival and local recurrence free survival at 1, 3 and 5 years were 76, 57 and 47, and 79, 60 and 51 % respectively. 19 patients (15.5 %) were diagnosed with distant metastases. Univariate analysis revealed significantly improved OS and LRFS for treatment of tumors after primary diagnosis, first series of irradiation and radiation dose ≥60 Gy. Multivariate analysis revealed only treatment in primary situation as an independent prognostic factor for OS and LRFS. Acute CTC grade III mucositis was seen in 5 patients (4.1 %) and CTC grade II dysgeusia in 19 patients (15.6 %). Dysgeusia, dysosmia and ocular toxicity were the most common late adverse

  20. The rationale for intensity-modulated proton therapy in geometrically challenging cases

    International Nuclear Information System (INIS)

    Intensity-modulated proton therapy (IMPT) delivered with beam scanning is currently available at a limited number of proton centers. However, a simplified form of IMPT, the technique of field ‘patching’, has long been a standard practice in proton therapy centers. In field patching, different parts of the target volume are treated from different directions, i.e., a part of the tumor gets either full dose from a radiation field, or almost no dose. Thus, patching represents a form of binary intensity modulation. This study explores the limitations of the standard binary field patching technique, and evaluates possible dosimetric advantages of continuous dose modulations in IMPT. Specifics of the beam delivery technology, i.e., pencil beam scanning versus passive scattering and modulation, are not investigated. We have identified two geometries of target volumes and organs at risk (OAR) in which the use of field patching is severely challenged. We focused our investigations on two patient cases that exhibit these geometries: a paraspinal tumor case and a skull-base case. For those cases we performed treatment planning comparisons of three-dimensional conformal proton therapy (3DCPT) with field patching versus IMPT, using commercial and in-house software, respectively. We also analyzed the robustness of the resulting plans with respect to systematic setup errors of ±1 mm and range errors of ±2.5 mm. IMPT is able to better spare OAR while providing superior dose coverage for the challenging cases identified above. Both 3DCPT and IMPT are sensitive to setup errors and range uncertainties, with IMPT showing the largest effect. Nevertheless, when delivery uncertainties are taken into account IMPT plans remain superior regarding target coverage and OAR sparing. On the other hand, some clinical goals, such as the maximum dose to OAR, are more likely to be unmet with IMPT under large range errors. IMPT can potentially improve target coverage and OAR sparing in

  1. Boosting foundations and algorithms

    CERN Document Server

    Schapire, Robert E

    2012-01-01

    Boosting is an approach to machine learning based on the idea of creating a highly accurate predictor by combining many weak and inaccurate "rules of thumb." A remarkably rich theory has evolved around boosting, with connections to a range of topics, including statistics, game theory, convex optimization, and information geometry. Boosting algorithms have also enjoyed practical success in such fields as biology, vision, and speech processing. At various times in its history, boosting has been perceived as mysterious, controversial, even paradoxical.

  2. Volume and dosimetric changes and initial clinical experience of a two-step adaptive intensity modulated radiation therapy (IMRT) scheme for head and neck cancer

    International Nuclear Information System (INIS)

    Purpose: The aim of this study was to show the benefit of a two-step intensity modulated radiotherapy (IMRT) method by examining geometric and dosimetric changes. Material and Methods: Twenty patients with pharyngeal cancers treated with two-step IMRT combined with chemotherapy were included. Treatment-planning CT was done twice before IMRT (CT-1) and at the third or fourth week of IMRT for boost IMRT (CT-2). Transferred plans recalculated initial plan on CT-2 were compared with the initial plans on CT-1. Dose parameters were calculated for a total dose of 70 Gy for each plan. Results: The volumes of primary tumors and parotid glands on CT-2 regressed significantly. Parotid glands shifted medially an average of 4.2 mm on CT-2. The mean doses of the parotid glands in the initial and transferred plans were 25.2 Gy and 30.5 Gy, respectively. D2 (dose to 2% of the volume) doses of the spinal cord were 37.1 Gy and 39.2 Gy per 70 Gy, respectively. Of 15 patients in whom xerostomia scores could be evaluated 1–2 years after IMRT, no patient complained of grade 2 or more xerostomia. Conclusions: This two-step IMRT method as an adaptive RT scheme could adapt to changes in body contour, target volumes and risk organs during IMRT

  3. Chest wall desmoid tumours treated with definitive radiotherapy: a plan comparison of 3D conformal radiotherapy, intensity-modulated radiotherapy and volumetric-modulated arc radiotherapy

    OpenAIRE

    Liu, Jia; Ng, Diana; Lee, James; Stalley, Paul; Hong, Angela

    2016-01-01

    Purpose Definitive radiotherapy is often used for chest wall desmoid tumours due to size or anatomical location. The delivery of radiotherapy is challenging due to the large size and constraints of normal surrounding structures. We compared the dosimetry of 3D conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc radiotherapy (VMAT) to evaluate the best treatment option. Methods and materials Ten consecutive patients with inoperable chest wall de...

  4. The Quality Control of Intensity Modulated Radiation Therapy (IMRT) for ONCOR Siemens Linear Accelerators Using Film Dosimetry

    International Nuclear Information System (INIS)

    Intensity Modulated Radiation Therapy has made a significant progress in radiation therapy centers in recent years. In this method, each radiation beam is divided into many subfields that create a field with a modulated intensity. Considering the complexity of this method, the quality control for Intensity Modulated Radiation Therapy is a topic of interest for researchers. This article is about the various steps of planning and quality control of Siemens linear accelerators for Intensity Modulated Radiation Therapy, using film dosimetry. This article in addition to review of the techniques, discusses the details of experiments and possible sources of errors which are not mentioned in the protocols and other references. This project was carried out in Isfahan Milad hospital which has two Siemens ONCOR linear accelerators. Both accelerators are equipped with Multi-Leaf Collimators which enables us to perform Intensity Modulated Radiation Therapy delivery in the step-and-shoot method. The quality control consists of various experiments related to the sections of radiation therapy. In these experiments, the accuracy of some components such as treatment planning system, imaging device (CT), Multi-Leaf Collimators, control system of accelerator, and stability of the output are evaluated. The dose verification is performed using film dosimetry method. The films were KODAK-EDR2, which were calibrated before the experiments. One of the important steps is the comparison of the calculated dose with planning system and the measured dose in experiments. The results of the experiments in various steps have been acceptable according to the standard protocols. The calibration of Multi-Leaf Collimators and evaluation of the leakage through the leaves of Multi-Leaf Collimator was performed by using the film dosimetry and visual check. In comparison with calculated and measured dose, more that 80% of the points have to be in agreement within 3% of the value. In our experiments

  5. Modeling and Validation of Performance Limitations for the Optimal Design of Interferometric and Intensity-Modulated Fiber Optic Displacement Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Moro, Erik A. [Los Alamos National Laboratory

    2012-06-07

    Optical fiber sensors offer advantages over traditional electromechanical sensors, making them particularly well-suited for certain measurement applications. Generally speaking, optical fiber sensors respond to a desired measurand through modulation of an optical signal's intensity, phase, or wavelength. Practically, non-contacting fiber optic displacement sensors are limited to intensity-modulated and interferometric (or phase-modulated) methodologies. Intensity-modulated fiber optic displacement sensors relate target displacement to a power measurement. The simplest intensity-modulated sensor architectures are not robust to environmental and hardware fluctuations, since such variability may cause changes in the measured power level that falsely indicate target displacement. Differential intensity-modulated sensors have been implemented, offering robustness to such intensity fluctuations, and the speed of these sensors is limited only by the combined speed of the photodetection hardware and the data acquisition system (kHz-MHz). The primary disadvantages of intensity-modulated sensing are the relatively low accuracy (?m-mm for low-power sensors) and the lack of robustness, which consequently must be designed, often with great difficulty, into the sensor's architecture. White light interferometric displacement sensors, on the other hand, offer increased accuracy and robustness. Unlike their monochromatic-interferometer counterparts, white light interferometric sensors offer absolute, unambiguous displacement measurements over large displacement ranges (cm for low-power, 5 mW, sources), necessitating no initial calibration, and requiring no environmental or feedback control. The primary disadvantage of white light interferometric displacement sensors is that their utility in dynamic testing scenarios is limited, both by hardware bandwidth and by their inherent high-sensitivity to Doppler-effects. The decision of whether to use either an intensity-modulated

  6. Radiotherapy with post-operative intensity modulation for retroperitoneal sarcomas: acute toxicity profile; Radiotherapie avec modulation d'intensite postoperatoire des sarcomes retroperitoneaux: profil de toxicite aigue

    Energy Technology Data Exchange (ETDEWEB)

    Paumier, A.; Bonvalot, S.; Beaudre, A.; Terrier, P.; Lescesne, A.; Roberti, E.; Lefkopoulos, D.; Le Pechoux, C. [Institut de cancerologie Gustave-Roussy, Villejuif (France)

    2011-10-15

    The authors report the assessment of the acute toxicity of intensity-modulated conformational radiotherapy (IMRT) in the adjuvant post-operative treatment of peritoneal sarcomas. Patients have been operated and then irradiated with intensity modulation. Fourteen patients have been considered (seven for a primitive tumour, seven for relapses). Tumour types and sizes, previsional target volume (PTV), average prescribed dose are analysed. Acute toxicity is low. A longer follow-up is still required to assess the toxicity on the long term and the risk of a radio-induced cancer. Short communication

  7. Design and Implementation of Head and Neck Perspex Phantom for Intensity Modulated Radiation Therapy

    International Nuclear Information System (INIS)

    The aims of this study are to design, construct and evaluate the applicability of a head and neck Perspex phantom for dosimetric verification of intensity modulated radiation therapy (IMRT). Thermoluminescent dosimeters (TLDs) was used in this study. Consistency of the fabricated phantom readings was checked by multiple IMRT irradiations. The inter-fraction standard deviation among all TLDs’ measurement was 3.7%, and the averages of all repetitive measurements at OAR and PTV were comparable with TPS with a percentage variation of 4.8%, (SD 8.1) and P value ≻ 0.05 (95%, CI). These findings suggest the consistency and the reproducibility of the phantom and its applicability for IMRT treatment verification.

  8. Stereotactic Image-Guided Intensity Modulated Radiotherapy Using the HI-ART II Helical Tomotherapy System

    International Nuclear Information System (INIS)

    The highly integrated adaptive radiation therapy (HI-ART II) helical tomotherapy unit is a new radiotherapy machine designed to achieve highly precise and accurate treatments at all body sites. The precision and accuracy of the HI-ART II is similar to that provided by stereotactic radiosurgery systems, hence the historical distinction between external beam radiotherapy and stereotactic procedures based on differing precision requirements is removed for this device. The objectives of this work are: (1) to describe stereotactic helical tomotherapy processes (SRS, SBRT); (2) to show that the precision and accuracy of the HI-ART meet the requirements defined for SRS and SBRT; and (3) to describe the clinical implementation of a stereotactic image-guided intensity modulated radiation therapy (IG-IMRT) system that incorporates optical motion management

  9. High-resolution CW lidar altimetry using repeating intensity-modulated waveforms and Fourier transform reordering.

    Science.gov (United States)

    Campbell, Joel F; Lin, Bing; Nehrir, Amin R; Harrison, F Wallace; Obland, Michael D

    2014-10-15

    An interpolation method is described for range measurements of high precision and altimetry using repeating intensity-modulated continuous wave (IM-CW) lidar waveforms, where the range is determined by means of a cross-correlation between the digital form of the transmitted signal and the digitized return signal collected by the lidar receiver. This method uses reordering of the array elements in the frequency domain to convert a repeating synthetic pulse signal to single highly interpolated pulse. The computation of this processing is marginally greater than the correlation itself, as it only involves reordering of the correlation in the frequency domain, which makes it possible to implement this in a real time application. It is shown through theoretical arguments and flight-testing that this is a viable method for high-speed interpolated range measurements. Standard deviation is 0.75 m over water with only 350 mw of transmitted power at 2600 m. PMID:25361160

  10. Simple tool for prediction of parotid gland sparing in intensity-modulated radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Gensheimer, Michael F. [Department of Radiation Oncology, University of Washington Medical Center, Seattle, WA (United States); Hummel-Kramer, Sharon M., E-mail: sharonhummel@comcast.net [Department of Radiation Oncology, VA Puget Sound Health Care System, Seattle, WA (United States); Cain, David; Quang, Tony S. [Department of Radiation Oncology, VA Puget Sound Health Care System, Seattle, WA (United States)

    2015-10-01

    Sparing one or both parotid glands is a key goal when planning head and neck cancer radiation treatment. If the planning target volume (PTV) overlaps one or both parotid glands substantially, it may not be possible to achieve adequate gland sparing. This finding results in physicians revising their PTV contours after an intensity-modulated radiation therapy (IMRT) plan has been run and reduces workflow efficiency. We devised a simple formula for predicting mean parotid gland dose from the overlap of the parotid gland and isotropically expanded PTV contours. We tested the tool using 44 patients from 2 institutions and found agreement between predicted and actual parotid gland doses (mean absolute error = 5.3 Gy). This simple method could increase treatment planning efficiency by improving the chance that the first plan presented to the physician will have optimal parotid gland sparing.

  11. Image-Based Dynamic Multileaf Collimator Tracking of Moving Targets During Intensity-Modulated Arc Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Poulsen, Per Rugaard, E-mail: perpolse@rm.dk [Institute of Clinical Medicine, Aarhus University, Aarhus (Denmark); Department of Oncology, Aarhus University Hospital, Aarhus (Denmark); Fledelius, Walther [Department of Oncology, Aarhus University Hospital, Aarhus (Denmark); Cho, Byungchul [Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Keall, Paul [Sydney Medical School, University of Sydney, Sydney (Australia)

    2012-06-01

    Purpose: Intensity-modulated arc therapy (IMAT) enables efficient and highly conformal dose delivery. However, intrafraction motion may compromise the delivered target dose distribution. Dynamic multileaf collimator (DMLC) tracking can potentially mitigate the impact of target motion on the dose. The purpose of this study was to use a single kV imager for DMLC tracking during IMAT and to investigate the ability of this tracking to maintain the dose distribution. Methods: A motion phantom carrying a two-dimensional (2D) ion chamber array and buildup material with an embedded gold marker reproduced eight representative tumor trajectories (four lung tumors, four prostate). For each trajectory, a low and high IMAT plan were delivered with and without DMLC tracking. The three-dimensional (3D) real-time target position signal for tracking was provided by fluoroscopic kV images acquired immediately before and during treatment. For each image, the 3D position of the embedded marker was estimated from the imaged 2D position by a probability-based method. The MLC leaves were continuously refitted to the estimated 3D position. For lung, prediction was used to compensate for the tracking latency. The delivered 2D dose distributions were measured with the ion chamber array and compared with a reference dose distribution delivered without target motion using a 3%/3 mm {gamma}-test. Results: For lung tumor motion, tracking reduced the mean {gamma}-failure rate from 38% to 0.7% for low-modulation IMAT plans and from 44% to 2.8% for high-modulation plans. For prostate, the {gamma}-failure rate reduction was from 19% to 0% (low modulation) and from 20% to 2.7% (high modulation). The dominant contributor to the residual {gamma}-failures during tracking was target localization errors for most lung cases and leaf fitting errors for most prostate cases. Conclusion: Image-based tracking for IMAT was demonstrated for the first time. The tracking greatly improved the dose distributions to

  12. Image-Based Dynamic Multileaf Collimator Tracking of Moving Targets During Intensity-Modulated Arc Therapy

    International Nuclear Information System (INIS)

    Purpose: Intensity-modulated arc therapy (IMAT) enables efficient and highly conformal dose delivery. However, intrafraction motion may compromise the delivered target dose distribution. Dynamic multileaf collimator (DMLC) tracking can potentially mitigate the impact of target motion on the dose. The purpose of this study was to use a single kV imager for DMLC tracking during IMAT and to investigate the ability of this tracking to maintain the dose distribution. Methods: A motion phantom carrying a two-dimensional (2D) ion chamber array and buildup material with an embedded gold marker reproduced eight representative tumor trajectories (four lung tumors, four prostate). For each trajectory, a low and high IMAT plan were delivered with and without DMLC tracking. The three-dimensional (3D) real-time target position signal for tracking was provided by fluoroscopic kV images acquired immediately before and during treatment. For each image, the 3D position of the embedded marker was estimated from the imaged 2D position by a probability-based method. The MLC leaves were continuously refitted to the estimated 3D position. For lung, prediction was used to compensate for the tracking latency. The delivered 2D dose distributions were measured with the ion chamber array and compared with a reference dose distribution delivered without target motion using a 3%/3 mm γ-test. Results: For lung tumor motion, tracking reduced the mean γ-failure rate from 38% to 0.7% for low-modulation IMAT plans and from 44% to 2.8% for high-modulation plans. For prostate, the γ-failure rate reduction was from 19% to 0% (low modulation) and from 20% to 2.7% (high modulation). The dominant contributor to the residual γ-failures during tracking was target localization errors for most lung cases and leaf fitting errors for most prostate cases. Conclusion: Image-based tracking for IMAT was demonstrated for the first time. The tracking greatly improved the dose distributions to moving targets.

  13. Feasibility of an online adaptive replanning method for cranial frameless intensity-modulated radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, Juan Francisco, E-mail: jfcdrr@gmail.com [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain); San José, Sol [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain); Garrido, LLuís [Institut de Ciències del Cosmos i Departament ECM, Universitat de Barcelona, Barcelona (Spain); Puertas, Enrique; Moragues, Sandra; Pozo, Miquel [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain); Casals, Joan, E-mail: jfcdrr@yahoo.es [Departamento de Oncología Radioterápica, Hospital Quirón, Barcelona (Spain)

    2013-10-01

    To introduce an approach for online adaptive replanning (i.e., dose-guided radiosurgery) in frameless stereotactic radiosurgery, when a 6-dimensional (6D) robotic couch is not available in the linear accelerator (linac). Cranial radiosurgical treatments are planned in our department using intensity-modulated technique. Patients are immobilized using thermoplastic mask. A cone-beam computed tomography (CBCT) scan is acquired after the initial laser-based patient setup (CBCT{sub setup}). The online adaptive replanning procedure we propose consists of a 6D registration-based mapping of the reference plan onto actual CBCT{sub setup}, followed by a reoptimization of the beam fluences (“6D plan”) to achieve similar dosage as originally was intended, while the patient is lying in the linac couch and the original beam arrangement is kept. The goodness of the online adaptive method proposed was retrospectively analyzed for 16 patients with 35 targets treated with CBCT-based frameless intensity modulated technique. Simulation of reference plan onto actual CBCT{sub setup}, according to the 4 degrees of freedom, supported by linac couch was also generated for each case (4D plan). Target coverage (D99%) and conformity index values of 6D and 4D plans were compared with the corresponding values of the reference plans. Although the 4D-based approach does not always assure the target coverage (D99% between 72% and 103%), the proposed online adaptive method gave a perfect coverage in all cases analyzed as well as a similar conformity index value as was planned. Dose-guided radiosurgery approach is effective to assure the dose coverage and conformity of an intracranial target volume, avoiding resetting the patient inside the mask in a “trial and error” way so as to remove the pitch and roll errors when a robotic table is not available.

  14. Intensity modulated radiotherapy for sinonasal malignancies with a focus on optic pathway preservation

    Directory of Open Access Journals (Sweden)

    Chi Alexander

    2013-01-01

    Full Text Available Abstract Purpose To assess if intensity-modulated radiotherapy (IMRT can possibly lead to improved local control and lower incidence of vision impairment/blindness in comparison to non-IMRT techniques when treating sinonasal malignancies; what is the most optimal dose constraints for the optic pathway; and the impact of different IMRT strategies on optic pathway sparing in this setting. Methods and materials A literature search in the PubMed databases was conducted in July, 2012. Results Clinical studies on IMRT and 2D/3D (2 dimensional/3 dimensional RT for sinonasal malignancies suggest improved local control and lower incidence of severe vision impairment with IMRT in comparison to non-IMRT techniques. As observed in the non-IMRT studies, blindness due to disease progression may occur despite a lack of severe toxicity possibly due to the difficulty of controlling locally very advanced disease with a dose ≤ 70 Gy. Concurrent chemotherapy’s influence on the the risk of severe optic toxicity after radiotherapy is unclear. A maximum dose of ≤ 54 Gy with conventional fractionation to the optic pathway may decrease the risk of blindness. Increased magnitude of intensity modulation through increasing the number of segments, beams, and using a combination of coplanar and non-coplanar arrangements may help increase dose conformality and optic pathway sparing when IMRT is used. Conclusion IMRT optimized with appropriate strategies may be the treatment of choice for the most optimal local control and optic pathway sparing when treating sinonasal malignancy.

  15. Robust Intensity Modulated Proton Therapy (IMPT) Increases Estimated Clinical Benefit in Head and Neck Cancer Patients

    Science.gov (United States)

    van Dijk, Lisanne V.; Steenbakkers, Roel J. H. M.; ten Haken, Bennie; van der Laan, Hans Paul; van ‘t Veld, Aart A.; Langendijk, Johannes A.; Korevaar, Erik W.

    2016-01-01

    Purpose To compare the clinical benefit of robust optimized Intensity Modulated Proton Therapy (minimax IMPT) with current photon Intensity Modulated Radiation Therapy (IMRT) and PTV-based IMPT for head and neck cancer (HNC) patients. The clinical benefit is quantified in terms of both Normal Tissue Complication Probability (NTCP) and target coverage in the case of setup and range errors. Methods and Materials For 10 HNC patients, PTV-based IMRT (7 fields), minimax and PTV-based IMPT (2, 3, 4, 5 and 7 fields) plans were tested on robustness. Robust optimized plans differed from PTV-based plans in that they target the CTV and penalize possible error scenarios, instead of using the static isotropic CTV-PTV margin. Perturbed dose distributions of all plans were acquired by simulating in total 8060 setup (±3.5 mm) and range error (±3%) combinations. NTCP models for xerostomia and dysphagia were used to predict the clinical benefit of IMPT versus IMRT. Results The robustness criterion was met in the IMRT and minimax IMPT plans in all error scenarios, but this was only the case in 1 of 40 PTV-based IMPT plans. Seven (out of 10) patients had relatively large NTCP reductions in minimax IMPT plans compared to IMRT. For these patients, xerostomia and dysphagia NTCP values were reduced by 17.0% (95% CI; 13.0–21.1) and 8.1% (95% CI; 4.9–11.2) on average with minimax IMPT. Increasing the number of fields did not contribute to plan robustness, but improved organ sparing. Conclusions The estimated clinical benefit in terms of NTCP of robust optimized (minimax) IMPT is greater than that of IMRT and PTV-based IMPT in HNC patients. Furthermore, the target coverage of minimax IMPT plans in the presence of errors was comparable to IMRT plans. PMID:27030987

  16. Sequential attack with intensity modulation on the differential-phase-shift quantum-key-distribution protocol

    International Nuclear Information System (INIS)

    In this paper, we discuss the security of the differential-phase-shift quantum-key-distribution (DPSQKD) protocol by introducing an improved version of the so-called sequential attack, which was originally discussed by Waks et al. [Phys. Rev. A 73, 012344 (2006)]. Our attack differs from the original form of the sequential attack in that the attacker Eve modulates not only the phases but also the amplitude in the superposition of the single-photon states which she sends to the receiver. Concentrating especially on the 'discretized Gaussian' intensity modulation, we show that our attack is more effective than the individual attack, which had been the best attack up to present. As a result of this, the recent experiment with communication distance of 100 km reported by Diamanti et al. [Opt. Express 14, 13073 (2006)] turns out to be insecure. Moreover, it can be shown that in a practical experimental setup which is commonly used today, the communication distance achievable by the DPSQKD protocol is less than 95 km

  17. Intensity-modulated radiation therapy: not a dry eye in the house

    International Nuclear Information System (INIS)

    Inverse planned intensity-modulated radiation therapy (IMRT) has been applied to patients in a conformal fashion in order to avoid the lacrimal gland. In the present study, we report a patient in which a potential planned dose of 63 Gy to the lacrimal gland for a conventional plan was reduced to 12 Gy to the lacrimal gland for the IMRT plan. Dose objective inverse planning was provided using a Pinnacle treatment planning computer and treatment was delivered using a Varian dynamic multileaf collimator (MLC) on a Varian linear accelerator. Because multiple MLC segments are used to deliver the modulated treatment, conventional dose checks by manual calculation are not practical. To aid in an alternative dosimetric verification process, the Pinnacle planning computer has two unique dose tools, which provide axial and beams eye view doses on user-specified check phantoms. The combined field axial dose tool matched our ion chamber dose checks within ± 2.4% at the isocentre. The individual beams eye view dose tool matched film dose maps within ± 3% in the umbra Copyright (2004) Blackwell Publishing Asia Pty Ltd

  18. Detection of light and vibration modulates bioluminescence intensity in the glowworm, Arachnocampa flava.

    Science.gov (United States)

    Mills, Rebecca; Popple, Julie-Anne; Veidt, Martin; Merritt, David John

    2016-04-01

    Glowworms are larval fungus gnats that emit light from a specialised abdominal light organ. The light attracts small arthropod prey to their web-like silk snares. Larvae glow throughout the night and can modulate their bioluminescence in response to sensory input. To better understand light output regulation and its ecological significance, we examined the larvae's reaction to light exposure, vibration and sound. Exposure to a 5-min light pulse in the laboratory causes larvae to exponentially decrease their light output over 5-10 min until they completely switch off. They gradually return to pre-exposure levels but do not show a rebound. Larvae are most sensitive to ultraviolet light, then blue, green and red. Vibration of the larval snares results in a several-fold increase in bioluminescence over 20-30 s, followed by an exponential return to pre-exposure levels over 15-30 min. Under some conditions, larvae can respond to vibration by initiating bioluminescence when they are not glowing; however, the response is reduced compared to when they are glowing. We propose that inhibitory and excitatory mechanisms combine to modulate bioluminescence intensity by regulating biochemical reactions or gating the access of air to the light organ. PMID:26897608

  19. Linear Energy Transfer-Guided Optimization in Intensity Modulated Proton Therapy: Feasibility Study and Clinical Potential

    Energy Technology Data Exchange (ETDEWEB)

    Giantsoudi, Drosoula, E-mail: dgiantsoudi@partners.org [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Grassberger, Clemens; Craft, David; Niemierko, Andrzej; Trofimov, Alexei; Paganetti, Harald [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States)

    2013-09-01

    Purpose: To investigate the feasibility and potential clinical benefit of linear energy transfer (LET) guided plan optimization in intensity modulated proton therapy (IMPT). Methods and Materials: A multicriteria optimization (MCO) module was used to generate a series of Pareto-optimal IMPT base plans (BPs), corresponding to defined objectives, for 5 patients with head-and-neck cancer and 2 with pancreatic cancer. A Monte Carlo platform was used to calculate dose and LET distributions for each BP. A custom-designed MCO navigation module allowed the user to interpolate between BPs to produce deliverable Pareto-optimal solutions. Differences among the BPs were evaluated for each patient, based on dose–volume and LET–volume histograms and 3-dimensional distributions. An LET-based relative biological effectiveness (RBE) model was used to evaluate the potential clinical benefit when navigating the space of Pareto-optimal BPs. Results: The mean LET values for the target varied up to 30% among the BPs for the head-and-neck patients and up to 14% for the pancreatic cancer patients. Variations were more prominent in organs at risk (OARs), where mean LET values differed by a factor of up to 2 among the BPs for the same patient. An inverse relation between dose and LET distributions for the OARs was typically observed. Accounting for LET-dependent variable RBE values, a potential improvement on RBE-weighted dose of up to 40%, averaged over several structures under study, was noticed during MCO navigation. Conclusions: We present a novel strategy for optimizing proton therapy to maximize dose-averaged LET in tumor targets while simultaneously minimizing dose-averaged LET in normal tissue structures. MCO BPs show substantial LET variations, leading to potentially significant differences in RBE-weighted doses. Pareto-surface navigation, using both dose and LET distributions for guidance, provides the means for evaluating a large variety of deliverable plans and aids in

  20. SU-E-T-234: Modulated Photon Radiotherapy (XMRT):The Impact of Incorporating Energy Modulation Into Intensity Modulated Radiotherapy (IMRT) Optimization

    Energy Technology Data Exchange (ETDEWEB)

    McGeachy, P; Khan, R [University of Calgary, Calgary, Alberta (Canada)

    2014-06-01

    Purpose: To develop a new radiotherapy plan optimization technique that, for a given organ geometry, will find the optimal photon beam energies and fluences to produce a desirable dose distribution. This new modulated (both in energy and fluence) photon radiotherapy (XMRT) was compared with intensity modulated radiotherapy (IMRT) for a simple organ geometry. Methods: The XMRT optimization was formulated using a linear programming approach where the objective function is the mean dose to the healthy organs and dose-point constraints were assigned to each organ of interest. The organ geometry consisted of a target, two organs at risk (OARs), and normal tissue. A seven-equispaced-coplanar beam arrangement was used. For conventional IMRT, only 6 MV beams were available, while XMRT was optimized using 6 and 18 MV beams. A prescribed dose (PD) of 72 GY was assigned to the target, with upper and lower bounds of 110% and 95% of the PD, respectively. Both OARs were assigned a maximum dose of 64 Gy, while the normal tissue was assigned a maximum dose of 66 Gy. A numerical solver, Gurobi, generated solutions for the XMRT and IMRT problems. The dose-volume histograms from IMRT and XMRT solutions were compared. Results: The maximum, minimum, mean, and homogeneity of the dose to the target were comparable between IMRT and XMRT. Though IMRT had improved dose conformity relative to XMRT, XMRT reduced the mean dose to both OARs by more than 1 Gy. For normal tissue, an increase of 5 Gy in mean dose and 27 percent in integral dose was seen for IMRT relative to XMRT. Conclusion: This work demonstrates the benefits of simultaneously modulating photon beam energy and fluence using our XMRT approach in a given phantom geometry. While target coverage was comparable, dose to healthy structures was reduced using XMRT.

  1. Progress on the 140 KV, 10 Megawatt Peak, 1 Megawatt Average Polyphase Quasi-Resonant Bridge, Boost Converter/Modulator for the Spallation Neutron Source (SNS) Klystron Power System

    CERN Document Server

    Reass, W A; Gribble, R F; Lynch, M T; Tallerico, P J; Reass, William A.; Doss, James D.; Gribble, Robert F.; Lynch, Michael T.; Tallerico, Paul J.

    2000-01-01

    This paper describes electrical design and operational characteristics of a zero-voltage-switching 20 kHz polyphase bridge, boost converter/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three "H-Bridge" IGBT switching networks are used to generate the polyphase 20 kHz transformers primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. PWM (pulse width modulation) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt peaking is used on the transformer secondary to ...

  2. Direct-aperture optimization applied to selection of beam orientations in intensity-modulated radiation therapy

    International Nuclear Information System (INIS)

    Direct-aperture optimization (DAO) was applied to iterative beam-orientation selection in intensity-modulated radiation therapy (IMRT), so as to ensure a realistic segmental treatment plan at each iteration. Nested optimization engines dealt separately with gantry angles, couch angles, collimator angles, segment shapes, segment weights and wedge angles. Each optimization engine performed a random search with successively narrowing step sizes. For optimization of segment shapes, the filtered backprojection (FBP) method was first used to determine desired fluence, the fluence map was segmented, and then constrained direct-aperture optimization was used thereafter. Segment shapes were fully optimized when a beam angle was perturbed, and minimally re-optimized otherwise. The algorithm was compared with a previously reported method using FBP alone at each orientation iteration. An example case consisting of a cylindrical phantom with a hemi-annular planning target volume (PTV) showed that for three-field plans, the method performed better than when using FBP alone, but for five or more fields, neither method provided much benefit over equally spaced beams. For a prostate case, improved bladder sparing was achieved through the use of the new algorithm. A plan for partial scalp treatment showed slightly improved PTV coverage and lower irradiated volume of brain with the new method compared to FBP alone. It is concluded that, although the method is computationally intensive and not suitable for searching large unconstrained regions of beam space, it can be used effectively in conjunction with prior class solutions to provide individually optimized IMRT treatment plans

  3. On the Capacity of the Intensity-Modulation Direct-Detection Optical Broadcast Channel

    KAUST Repository

    Chaaban, Anas

    2016-01-12

    The capacity of the intensity-modulation directdetection optical broadcast channel (OBC) is investigated, under both average and peak intensity constraints. An outer bound on the capacity region is derived by adapting Bergmans’ approach to the OBC. Inner bounds are derived by using superposition coding with either truncated-Gaussian (TG) distributions or discrete distributions. While the discrete distribution achieves higher rates, the TG distribution leads to a simpler representation of the achievable rate region. At high signal-to-noise ratio (SNR), it is shown that the TG distribution is nearly optimal. It achieves the symmetric-capacity within a constant gap (independent of SNR), which approaches half a bit as the number of users grows. It also achieves the capacity region within a constant gap. At low SNR, it is shown that on-off keying (OOK) with time-division multipleaccess (TDMA) is optimal. This is interesting in practice since both OOK and TDMA have low complexity. At moderate SNR (typically [0,8] dB), a discrete distribution with a small alphabet size achieves fairly good performance.

  4. On the Capacity Region of the Intensity-Modulation Direct-Detection Optical Broadcast Channel

    KAUST Repository

    Chaaban, Anas

    2015-08-11

    The capacity of the intensity-modulation direct-detection free-space optical broadcast channel (OBC) is investigated. The Gaussian model with input-independent Gaussian noise is used, with both average and peak intensity constraints. An outer bound on the capacity region is derived by adapting Bergmans\\' approach to the OBC. Inner bounds are derived by using superposition coding with either truncated-Gaussian distributions or discrete distributions. While the discrete input distribution achieves higher rates than the truncated-Gaussian distribution, the latter allows expressing the achievable rate region in a closed form. At high signal-to-noise ratio (SNR), it is shown that the truncated-Gaussian distribution is nearly optimal. It achieves the symmetric-capacity within a constant gap (independent of SNR), which approaches half a bit as the number of users grows large. It also achieves the capacity region within a constant gap, which depends on the number of users. At low SNR, it is shown that on-off keying with time-division multiple-access (TDMA) is optimal, as it achieves any point on the boundary of the developed outer bound. This is interesting in practice since both OOK and TDMA have low complexity. At moderate SNR (typically [0,8] dB), a discrete distribution with a small alphabet size achieves a fairly good performance in terms of symmetric rate.

  5. Feasibility Study of Moderately Accelerated Intensity-Modulated Radiotherapy Plus Concurrent Weekly Cisplatin After Induction Chemotherapy in Locally Advanced Head-and Neck Cancer

    International Nuclear Information System (INIS)

    Purpose: To evaluate the feasibility and efficacy of moderately accelerated intensity-modulated radiation therapy (IMRT) along with weekly cisplatin, after induction chemotherapy, in patients with locally advanced unresectable head and neck cancer (HNC). Methods and Materials: Patients with Stage III or IV locally advanced HNC, without progressive disease after three courses of induction chemotherapy, received concurrent chemo-IMRT (weekly cisplatin 30 mg/m2 plus simultaneous integrated boost IMRT). A total of 67.5 Gy in 30 fractions were delivered to primary tumor and involved nodes, 60 Gy in 30 fractions to high-risk nodal areas, and 55.5 Gy in 30 fractions to low-risk nodal areas. Results: In all, 36 patients (median age, 56 years) with International Union Against Cancer (UICC) Stage III (n = 5) and IV (n = 31) were included. Of the 36 patients, 17 had received CF (cisplatin and 5-fluorouracil (CF) and 19 had received docetaxel cisplatin and 5-fluorouracil (DCF). During concurrent chemoradiation, 11 of 36 patients (30.5%) experienced Grade III mucositis (CF, 47%; DCF, 15%; p < 0.04). Grade III pharyngeal-esophageal toxicity was observed in 5 of 19 patients (26.3%; CF, 0.0%; DCF, 26.3%; p = 0.02). Two patients died of complications (5.5%). After chemoradiation, the complete response rate was 63.8%. Two-year local control was 88.7%. Two-year progression free survival and overall survival were 74.5% and 60.9%, respectively. Conclusions: In our experience, a moderately accelerated chemo-IMRT was feasible after induction chemotherapy. However, a noteworthy early death rate of 5.5% was observed. Intensive supportive care strategies should be defined to better manage radiation-induced toxic effects. Longer follow-up is required to determine the incidence of late radiation toxicities and tumor control rates.

  6. Lack of effect of glutamine administration to boost the innate immune system response in trauma patients in the intensive care unit

    OpenAIRE

    Pérez-Bárcena, Jon; Crespí, Catalina; Regueiro, Verónica; Marsé, Pedro; Raurich, Joan M; Ibáñez, Jordi; García de Lorenzo-Mateos, Abelardo; Bengoechea, José A.

    2010-01-01

    Introduction The use of glutamine as a dietary supplement is associated with a reduced risk of infection. We hypothesized that the underlying mechanism could be an increase in the expression and/or functionality of Toll-like receptors (TLR), key receptors sensing infections. The objective of this study was to evaluate whether glutamine supplementation alters the expression and functionality of TLR2 and TLR4 in circulating monocytes of trauma patients admitted to the intensive care unit (ICU)....

  7. A Treatment Planning and Acute Toxicity Comparison of Two Pelvic Nodal Volume Delineation Techniques and Delivery Comparison of Intensity-Modulated Radiotherapy Versus Volumetric Modulated Arc Therapy for Hypofractionated High-Risk Prostate Cancer Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To perform a comparison of two pelvic lymph node volume delineation strategies used in intensity-modulated radiotherapy (IMRT) for high risk prostate cancer and to determine the role of volumetric modulated arc therapy (VMAT). Methods and Materials: Eighteen consecutive patients accrued to an ongoing clinical trial were identified according to either the nodal contouring strategy as described based on lymphotropic nanoparticle-enhanced magnetic resonance imaging technology (9 patients) or the current Radiation Therapy Oncology Group (RTOG) consensus guidelines (9 patients). Radiation consisted of 45 Gy to prostate, seminal vesicles, and lymph nodes, with a simultaneous integrated boost to the prostate alone, to a total dose of 67.5 Gy delivered in 25 fractions. Prospective acute genitourinary and gastrointestinal toxicities were compared at baseline, during radiotherapy, and 3 months after radiotherapy. Each patient was retrospectively replanned using the opposite method of nodal contouring, and plans were normalized for dosimetric comparison. VMAT plans were also generated according to the RTOG method for comparison. Results: RTOG plans resulted in a significantly lower rate of genitourinary frequency 3 months after treatment. The dosimetric comparison showed that the RTOG plans resulted in both favorable planning target volume (PTV) coverage and lower organs at risk (OARs) and integral (ID) doses. VMAT required two to three arcs to achieve adequate treatment plans, we did not observe consistent dosimetric benefits to either the PTV or the OARs, and a higher ID was observed. However, treatment times were significantly shorter with VMAT. Conclusion: The RTOG guidelines for pelvic nodal volume delineation results in favorable dosimetry and acceptable acute toxicities for both the target and OARs. We are unable to conclude that VMAT provides a benefit compared with IMRT.

  8. A modular approach to intensity-modulated arc therapy optimization with noncoplanar trajectories

    Science.gov (United States)

    Papp, Dávid; Bortfeld, Thomas; Unkelbach, Jan

    2015-07-01

    Utilizing noncoplanar beam angles in volumetric modulated arc therapy (VMAT) has the potential to combine the benefits of arc therapy, such as short treatment times, with the benefits of noncoplanar intensity modulated radiotherapy (IMRT) plans, such as improved organ sparing. Recently, vendors introduced treatment machines that allow for simultaneous couch and gantry motion during beam delivery to make noncoplanar VMAT treatments possible. Our aim is to provide a reliable optimization method for noncoplanar isocentric arc therapy plan optimization. The proposed solution is modular in the sense that it can incorporate different existing beam angle selection and coplanar arc therapy optimization methods. Treatment planning is performed in three steps. First, a number of promising noncoplanar beam directions are selected using an iterative beam selection heuristic; these beams serve as anchor points of the arc therapy trajectory. In the second step, continuous gantry/couch angle trajectories are optimized using a simple combinatorial optimization model to define a beam trajectory that efficiently visits each of the anchor points. Treatment time is controlled by limiting the time the beam needs to trace the prescribed trajectory. In the third and final step, an optimal arc therapy plan is found along the prescribed beam trajectory. In principle any existing arc therapy optimization method could be incorporated into this step; for this work we use a sliding window VMAT algorithm. The approach is demonstrated using two particularly challenging cases. The first one is a lung SBRT patient whose planning goals could not be satisfied with fewer than nine noncoplanar IMRT fields when the patient was treated in the clinic. The second one is a brain tumor patient, where the target volume overlaps with the optic nerves and the chiasm and it is directly adjacent to the brainstem. Both cases illustrate that the large number of angles utilized by isocentric noncoplanar VMAT plans

  9. High dose for prostate irradiation with image guided radiotherapy: Contribution of intensity modulation arc-therapy

    International Nuclear Information System (INIS)

    Purpose: To compare two Intensity Modulated Radiation Therapy (IMRT) techniques for prostate cancer: the Volumetric Modulated Arc Therapy (VMAT) and the 'Step and Shoot' technique (S and S). Materials and methods: VMAT and S and S plans (RX 18 MV) were created and compared (Wilcoxon test) for 10 patients. The dosimetric goal of both treatments was to deliver 46 Gy to the seminal vesicles and 80 Gy to the prostate, while respecting the dose constrains in the organs at risk of toxicity. For one patient, the two techniques were compared for dose painting and escalation in target volumes defined on MRI and registered thanks to intra-prostatic fiducial. Results: VMAT, compared to S and S, offered: an increase of the PTV2s (prostate) volume receiving 77 to 80 Gy and a decrease of V82 and V83; a decrease of V4 to V6, V16 to V23, and V69 to V73 for the rectal wall; a decrease of V25 for the bladder wall; a decrease of V21 to V43 for the femoral heads; a decrease of V26 to V44 and V72 to V80 but an increase of V1 to V21 and V49 to V60 for the healthy tissues. The Conformal Index 'COIN' was better with VMAT than S and S (0.60 to 0.66). The delivered MU were significantly reduced with VMAT (8% mean) as well as the delivery time (4 min to 1.5 min). VMAT allowed delivering theoretically 90 Gy in the peripheral zone and 100 Gy in the tumor. Conclusion: In case of prostate irradiation, VMAT shows improvement compared with S and S. In particular, organs at risk are better spared, the delivery time is shortened and the number of delivered UM is decreased. (authors)

  10. Study on the possibility of using a 60 Co therapeutical unity in Intensity Modulated Radiotherapy (IMRT)

    International Nuclear Information System (INIS)

    With the increasing advances in complex treatment techniques, there is a tendency to obtain more sophisticated equipment to deliver the dose. The use of 3D conformal radiotherapy is now routine in many radiotherapy facilities as well as the utilization of intensity modulated radiotherapy (IMRT). Both are usually implemented using linear accelerators equipped with multi leaves collimators, which create the conformity and the fluence distributions required. However, the complexity of increasingly sophisticated equipment, such as linear accelerators, requires a frequent quality control of their operation, as well as a detailed and constant maintenance. Even carrying out these procedures, the accelerators may present technical problems interrupting for a long time a treatment using the IMRT technique. Despite the clear practical and technological advantages that linear accelerators have on 60Co irradiators, these devices occupy an important place in radiotherapy, mainly due to the low cost of equipment installation and maintenance when compared to those required by accelerators. Many radiotherapy facilities that work with IMRT have tele therapeutic isocentric 60Co units. In principle, such equipment would be able to be used for treatment with IMRT using compensating blocks to modulate the beam. This study investigates this possibility and shows that it is feasible. The comparison of treatment plans of a head-and-neck cancer and other of a cancer of the central nervous system, based on a 60Co irradiator and a Linac 2300 C/D, presented advantages for the 60Co irradiator. Furthermore; the delivery of dose obtained with the two systems showed themselves equivalent when compared to their respective plans. (author)

  11. Dosimetric analysis of daily use of IGRT in prostate treatment with intensity modulated

    International Nuclear Information System (INIS)

    The main application of image-guided radiotherapy (IGRT) in the cancer prostate treatment is to ensure the delivery of the prescribed dose to the tumor. With the modality cone beam computed tomography (CBCT) prostate, seminal vesicles, bladder and rectum can be previewed before each treatment and the actual dose delivered to these organs can be controlled, through the alignment of patient isocenter. The aim of this study was to analyze the tumor coverage and dose to organs at risk effectively obtained during the patient's treatment. Three patients with prostate cancer were treated with intensity modulated radiotherapy (IMRT) or volumetric modulated arc radiotherapy (VMAT) techniques with 74 Gy and 2 Gy per fraction. It was performed daily isocenter location of the prostate with CBCT. A radioncologist drew the clinical target volume (CTV), rectum and bladder in CBCT's and treatment fields were applied retrospectively in each CBCT for dose calculation. For the CTV it was considered the D95 (dose that covers 95% of the volume), for the rectum V50 (volume receiving 50 Gy), V60, V65 and V70 and for bladder V65 and V70. The average D95 of the prostate after the offset was 202 cGy, the V50, V60 and V65 of the rectum for one patient was reduced by 9.6%, 16.6% and 31%, respectively, and V65 of the bladder to another patient was also reduced by 3.5% in IGRT. The results showed that the use of IGRT provided a reduction in the irradiated volume of healthy organs. Thus it is concluded that the use of daily CBCT allows reproducibility of treatment, reducing delayed toxicities and increasing the probability of tumor control. (author)

  12. Estimating the costs of intensity-modulated and 3-dimensional conformal radiotherapy in Ontario

    Science.gov (United States)

    Yong, J.H.E.; McGowan, T.; Redmond-Misner, R.; Beca, J.; Warde, P.; Gutierrez, E.; Hoch, J.S.

    2016-01-01

    Background Radiotherapy is a common treatment for many cancers, but up-to-date estimates of the costs of radiotherapy are lacking. In the present study, we estimated the unit costs of intensity-modulated radiotherapy (imrt) and 3-dimensional conformal radiotherapy (3D-crt) in Ontario. Methods An activity-based costing model was developed to estimate the costs of imrt and 3D-crt in prostate cancer. It included the costs of equipment, staff, and supporting infrastructure. The framework was subsequently adapted to estimate the costs of radiotherapy in breast cancer and head-and-neck cancer. We also tested various scenarios by varying the program maturity and the use of volumetric modulated arc therapy (vmat) alongside imrt. Results From the perspective of the health care system, treating prostate cancer with imrt and 3D-crt respectively cost $12,834 and $12,453 per patient. The cost of radiotherapy ranged from $5,270 to $14,155 and was sensitive to analytic perspective, radiation technique, and disease site. Cases of head-and-neck cancer were the most costly, being driven by treatment complexity and fractions per treatment. Although imrt was more costly than 3D-crt, its cost will likely decline over time as programs mature and vmat is incorporated. Conclusions Our costing model can be modified to estimate the costs of 3D-crt and imrt for various disease sites and settings. The results demonstrate the important role of capital costs in studies of radiotherapy cost from a health system perspective, which our model can accommodate. In addition, our study established the need for future analyses of imrt cost to consider how vmat affects time consumption.

  13. Dosimetric comparison of hybrid volumetric-modulated arc therapy, volumetric-modulated arc therapy, and intensity-modulated radiation therapy for left-sided early breast cancer.

    Science.gov (United States)

    Lin, Jia-Fu; Yeh, Dah-Cherng; Yeh, Hui-Ling; Chang, Chen-Fa; Lin, Jin-Ching

    2015-01-01

    To compare the dosimetric performance of 3 different treatment techniques: hybrid volumetric-modulated arc therapy (hybrid-VMAT), pure-VMAT, and fixed-field intensity-modulated radiation therapy (F-IMRT) for whole-breast irradiation of left-sided early breast cancer. The hybrid-VMAT treatment technique and 2 other treatment techniques—pure-VMAT and F-IMRT—were compared retrospectively in 10 patients with left-sided early breast cancer. The treatment plans of these patients were replanned using the same contours based on the original computed tomography (CT) data sets. Dosimetric parameters were calculated to evaluate plan quality. Total monitor units (MUs) and delivery time were also recorded and evaluated. The hybrid-VMAT plan generated the best results in dose coverage of the target and the dose uniformity inside the target (p lung irradiated to doses of 20 Gy (V(20 Gy)) and 5 Gy (V(5 Gy)) by the hybrid-VMAT plan were significantly less than those of the F-IMRT and the pure-VMAT plans. The volume of ipsilateral lung irradiated to a dose of 5 Gy was significantly less using the hybrid-VMAT plan than that using the F-IMRT or the pure-VMAT plan. The total mean MUs for the hybrid-VMAT plan were significantly less than those for the F-IMRT or the pure-VMAT plan. The mean machine delivery time was 3.23 ± 0.29 minutes for the hybrid-VMAT plans, which is longer than that for the pure-VMAT plans but shorter than that for the F-IMRT plans. The hybrid-VMAT plan is feasible for whole-breast irradiation of left-sided early breast cancer. PMID:26116150

  14. Intensity modulated radiotherapy treatment for prostate cancer, first experience in Chile

    International Nuclear Information System (INIS)

    Background: Intensity modulated radiotherapy (IMRT) is an important step forward in cancer treatment. Aim: To report the first experience in Chile with IMRT for prostate cancer and compare the results obtained with different doses. Patients and Methods: From January 1997 through June 2008, 156 patients with a mean age of 70 years, were treated with radiotherapy and 121 with IMRT. Patients were staged according to American Commission on Cancer Staging. Their biochemical relapse risk was classified according to the MD Anderson classification. Patients were routinely checked during and after therapy to evaluate side effects and relapse. Results: Median follow up was 46 months (4-120). Overall five years survival was 85%. Biochemical relapse free five years survival for low, intermediate and high risk patients was 100, 82 and 70%, respectively. Biochemical relapse free survival for patients receiving radiotherapy doses over 76 Gy was 83%, compared to 30% for those receiving lower doses (p < 0.05). Urinary and gastrointestinal acute toxicity was low in 80% and 90% of patients respectively. Late toxicity developed in less than 3% of patients. Conclusions: IMRT for prostate cancer is readily available and safe in Chile. Biochemical disease free survival improved with higher doses with low toxicity rates Background: Intensity modulated radiotherapy (IMRT) is an important step forward in cancer treatment. Aim: To report the first experience in Chile with IMRT for prostate cancer and compare the results obtained with different doses. Patients and Methods: From January 1997 through June 2008, 156 patients with a mean age of 70 years, were treated with radiotherapy and 121 with IMRT. Patients were staged according to American Commission on Cancer Staging. Their biochemical relapse risk was classified according to the MD Anderson classification. Patients were routinely checked during and after therapy to evaluate side effects and relapse. Results: Median follow up was 46 months

  15. Intensity-modulated radiotherapy protocol for patients with low risk prostate cancer

    International Nuclear Information System (INIS)

    Full text: Introduction: Prostate cancer is the second most common non-dermatological malignant disease in men. The aim is to create a protocol for intensity modulated radiation therapy of prostate cancer in patients with low risk. These are patients with primary tumor T1- 2a, Gleason score ≤ 6 , iPSA < 10 ng / ml. What you will learn: The main treatment strategies for locally limited prostate cancer with a life expectancy of over 10 years are percutaneous radiotherapy (RT) , brachytherapy , radical prostatectomy and active tracking. NCCN recommends RT in these patients to consist higher Total Focal Doses (TFD) (75,6 to 79,2 Gy) to implement them if possible by second-generation three-dimensional technique - modulated by intensity radiation therapy (MIRT) . It makes it possible to achieve conformity with the target distribution in an irregular shape. The main characteristic of MIRT is that each field consists of multiple segments that provide optimal allocation of police investigations in the target volume and limit the realized dose in critical organs. Discussion: Patients are scanned with immobilization of the lower extremities in the supine position with slice thickness 3 mm and preliminary preparation for performing CT of the pelvis. A clinical target volume includes CTV76 - the prostate gland and the seminal vesicles base, and PTV76 - CTV76 with a security zone 5 mm in all directions except for the rectal wall - 3 mm. Ltd. The prescribed Total Focal Dose is 76 Gy at Dally Focal Dose (DFD) 2 Gy. As a critical organs are set rectum, bladder, root penis and hips. Dosimetric plan is developed based on the segmentation of stationary radiation fields and rules for verification and implementation. Conclusion: As a technique that provides uniform distribution of the dose in the treated volume, simultaneously by lowering the dose in critical organs, MIRT decreased early and late toxicity that in the patients with prostate cancer is usually not life-threatening, but

  16. Incorporating geometric ray tracing to generate initial conditions for intensity modulated arc therapy optimization

    International Nuclear Information System (INIS)

    Purpose and background: Intensity modulated arc therapy (IMAT) is a rotational variant of Intensity modulated radiation therapy (IMRT) that is achieved by allowing the multileaf collimator (MLC) positions to vary as the gantry rotates around the patient. This work describes a method to generate an IMAT plan through the use of a fast ray tracing technique based on dosimetric and geometric information for setting initial MLC leaf positions prior to final IMAT optimization. Methods and materials: Three steps were used to generate an IMAT plan. The first step was to generate arcs based on anatomical contours. The second step was to generate ray importance factor (RIF) maps by ray tracing the dose distribution inside the planning target volume (PTV) to modify the MLC leaf positions of the anatomical arcs to reduce the maximum dose inside the PTV. The RIF maps were also segmented to create a new set of arcs to improve the dose to low dose voxels within the PTV. In the third step, the MLC leaf positions from all arcs were put through a leaf position optimization (LPO) algorithm and brought into a fast Monte Carlo dose calculation engine for a final dose calculation. The method was applied to two phantom cases, a clinical prostate case and the Radiological Physics Center (RPC)'s head and neck phantom. The authors assessed the plan improvements achieved by each step and compared plans with and without using RIF. They also compared the IMAT plan with an IMRT plan for the RPC phantom. Results: All plans that incorporated RIF and LPO had lower objective function values than those that incorporated LPO only. The objective function value was reduced by about 15% after the generation of RIF arcs and 52% after generation of RIF arcs and leaf position optimization. The IMAT plan for the RPC phantom had similar dose coverage for PTV1 and PTV2 (the same dose volume histogram curves), however, slightly lower dose to the normal tissues compared to a six-field IMRT plan. Conclusion: The

  17. Intensity-Modulated Whole Abdominal Radiotherapy After Surgery and Carboplatin/Taxane Chemotherapy for Advanced Ovarian Cancer: Phase I Study

    International Nuclear Information System (INIS)

    Purpose: To assess the feasibility and toxicity of consolidative intensity-modulated whole abdominal radiotherapy (WAR) after surgery and chemotherapy in high-risk patients with advanced ovarian cancer. Methods and Materials: Ten patients with optimally debulked ovarian cancer International Federation of Gynecology and Obstetrics Stage IIIc were treated in a Phase I study with intensity-modulated WAR up to a total dose of 30 Gy in 1.5-Gy fractions as consolidation therapy after adjuvant carboplatin/taxane chemotherapy. Treatment was delivered using intensity-modulated radiotherapy in a step-and-shoot technique (n = 3) or a helical tomotherapy technique (n = 7). The planning target volume included the entire peritoneal cavity and the pelvic and para-aortal node regions. Organs at risk were kidneys, liver, heart, vertebral bodies, and pelvic bones. Results: Intensity-modulated WAR resulted in an excellent coverage of the planning target volume and an effective sparing of the organs at risk. The treatment was well tolerated, and no severe Grade 4 acute side effects occurred. Common Toxicity Criteria Grade III toxicities were as follows: diarrhea (n = 1), thrombocytopenia (n = 1), and leukopenia (n = 3). Radiotherapy could be completed by all the patients without any toxicity-related interruption. Median follow-up was 23 months, and 4 patients had tumor recurrence (intraperitoneal progression, n = 3; hepatic metastasis, n = 1). Small bowel obstruction caused by adhesions occurred in 3 patients. Conclusions: The results of this Phase I study showed for the first time, to our knowledge, the clinical feasibility of intensity-modulated whole abdominal radiotherapy, which could offer a new therapeutic option for consolidation treatment of advanced ovarian carcinoma after adjuvant chemotherapy in selected subgroups of patients. We initiated a Phase II study to further evaluate the toxicity of this intensive multimodal treatment.

  18. A particle swarm optimization algorithm for beam angle selection in intensity-modulated radiotherapy planning

    International Nuclear Information System (INIS)

    Automatic beam angle selection is an important but challenging problem for intensity-modulated radiation therapy (IMRT) planning. Though many efforts have been made, it is still not very satisfactory in clinical IMRT practice because of overextensive computation of the inverse problem. In this paper, a new technique named BASPSO (Beam Angle Selection with a Particle Swarm Optimization algorithm) is presented to improve the efficiency of the beam angle optimization problem. Originally developed as a tool for simulating social behaviour, the particle swarm optimization (PSO) algorithm is a relatively new population-based evolutionary optimization technique first introduced by Kennedy and Eberhart in 1995. In the proposed BASPSO, the beam angles are optimized using PSO by treating each beam configuration as a particle (individual), and the beam intensity maps for each beam configuration are optimized using the conjugate gradient (CG) algorithm. These two optimization processes are implemented iteratively. The performance of each individual is evaluated by a fitness value calculated with a physical objective function. A population of these individuals is evolved by cooperation and competition among the individuals themselves through generations. The optimization results of a simulated case with known optimal beam angles and two clinical cases (a prostate case and a head-and-neck case) show that PSO is valid and efficient and can speed up the beam angle optimization process. Furthermore, the performance comparisons based on the preliminary results indicate that, as a whole, the PSO-based algorithm seems to outperform, or at least compete with, the GA-based algorithm in computation time and robustness. In conclusion, the reported work suggested that the introduced PSO algorithm could act as a new promising solution to the beam angle optimization problem and potentially other optimization problems in IMRT, though further studies need to be investigated

  19. Progress in Y-00 physical cipher for Giga bit/sec optical data communications (intensity modulation method)

    Science.gov (United States)

    Hirota, Osamu; Futami, Fumio

    2014-10-01

    To guarantee a security of Cloud Computing System is urgent problem. Although there are several threats in a security problem, the most serious problem is cyber attack against an optical fiber transmission among data centers. In such a network, an encryption scheme on Layer 1(physical layer) with an ultimately strong security, a small delay, and a very high speed should be employed, because a basic optical link is operated at 10 Gbit/sec/wavelength. We have developed a quantum noise randomied stream cipher so called Yuen- 2000 encryption scheme (Y-00) during a decade. This type of cipher is a completely new type random cipher in which ciphertext for a legitimate receiver and eavesdropper are different. This is a condition to break the Shannon limit in theory of cryptography. In addition, this scheme has a good balance on a security, a speed and a cost performance. To realize such an encryption, several modulation methods are candidates such as phase-modulation, intensity-modulation, quadrature amplitude modulation, and so on. Northwestern university group demonstrated a phase modulation system (α=η) in 2003. In 2005, we reported a demonstration of 1 Gbit/sec system based on intensity modulation scheme(ISK-Y00), and gave a design method for quadratic amplitude modulation (QAM-Y00) in 2005 and 2010. An intensity modulation scheme promises a real application to a secure fiber communication of current data centers. This paper presents a progress in quantum noise randomized stream cipher based on ISK-Y00, integrating our theoretical and experimental achievements in the past and recent 100 Gbit/sec(10Gbit/sec × 10 wavelengths) experiment.

  20. A new Monte Carlo-based treatment plan optimization approach for intensity modulated radiation therapy

    Science.gov (United States)

    Li, Yongbao; Tian, Zhen; Shi, Feng; Song, Ting; Wu, Zhaoxia; Liu, Yaqiang; Jiang, Steve; Jia, Xun

    2015-04-01

    Intensity-modulated radiation treatment (IMRT) plan optimization needs beamlet dose distributions. Pencil-beam or superposition/convolution type algorithms are typically used because of their high computational speed. However, inaccurate beamlet dose distributions may mislead the optimization process and hinder the resulting plan quality. To solve this problem, the Monte Carlo (MC) simulation method has been used to compute all beamlet doses prior to the optimization step. The conventional approach samples the same number of particles from each beamlet. Yet this is not the optimal use of MC in this problem. In fact, there are beamlets that have very small intensities after solving the plan optimization problem. For those beamlets, it may be possible to use fewer particles in dose calculations to increase efficiency. Based on this idea, we have developed a new MC-based IMRT plan optimization framework that iteratively performs MC dose calculation and plan optimization. At each dose calculation step, the particle numbers for beamlets were adjusted based on the beamlet intensities obtained through solving the plan optimization problem in the last iteration step. We modified a GPU-based MC dose engine to allow simultaneous computations of a large number of beamlet doses. To test the accuracy of our modified dose engine, we compared the dose from a broad beam and the summed beamlet doses in this beam in an inhomogeneous phantom. Agreement within 1% for the maximum difference and 0.55% for the average difference was observed. We then validated the proposed MC-based optimization schemes in one lung IMRT case. It was found that the conventional scheme required 106 particles from each beamlet to achieve an optimization result that was 3% difference in fluence map and 1% difference in dose from the ground truth. In contrast, the proposed scheme achieved the same level of accuracy with on average 1.2 × 105 particles per beamlet. Correspondingly, the computation time

  1. A treatment planning study of the potential of geometrical tracking for intensity modulated proton therapy of lung cancer

    DEFF Research Database (Denmark)

    af Rosenschöld, Per Munck; Aznar, Marianne C; Nygaard, Ditte E;

    2010-01-01

    Proton therapy of lung cancer holds the potential for a reduction of the volume of irradiated normal lung tissue. In this work we investigate the robustness of intensity modulated proton therapy (IMPT) plans to motion, and evaluate a geometrical tumour tracking method to compensate for tumour...

  2. A treatment planning study of the potential of geometrical tracking for intensity modulated proton therapy of lung cancer

    DEFF Research Database (Denmark)

    Munck af Rosenschöld, Per; Aznar, Marianne; Nygaard, Ditte Eklund;

    2010-01-01

    Proton therapy of lung cancer holds the potential for a reduction of the volume of irradiated normal lung tissue. In this work we investigate the robustness of intensity modulated proton therapy (IMPT) plans to motion, and evaluate a geometrical tumour tracking method to compensate for tumour mot...

  3. Minimising contralateral breast dose in post-mastectomy intensity-modulated radiotherapy by incorporating conformal electron irradiation

    NARCIS (Netherlands)

    van der Laan, Hans Paul; Korevaar, Erik W; Dolsma, Willemtje; Maduro, John H; Langendijk, Johannes A

    2010-01-01

    PURPOSE: To assess the potential benefit of incorporating conformal electron irradiation in intensity-modulated radiotherapy (IMRT) for loco-regional post-mastectomy RT. PATIENTS AND METHODS: Ten consecutive patients that underwent left-sided mastectomy were selected for this comparative planning st

  4. Treatment outcome and toxicity of intensity-modulated (chemo) radiotherapy in stage III non-small cell lung cancer patients

    NARCIS (Netherlands)

    Govaert, S.L.; Troost, E.G.C.; Schuurbiers, O.C.J.; Geus-Oei, L.F. de; Termeer, A.; Span, P.N.; Bussink, J.

    2012-01-01

    ABSTRACT: PURPOSE: The aim of this retrospective cohort study was to assess treatment outcome, and acute pulmonary and esophageal toxicity using intensity modulated (sequential/concurrent chemo)radiotherapy (IMRT) in locally advanced stage III non-small cell lung cancer (NSCLC). METHODS AND MATERIAL

  5. The potential benefit of swallowing sparing intensity modulated radiotherapy to reduce swallowing dysfunction : An in silico planning comparative study

    NARCIS (Netherlands)

    van der Laan, Hans Paul; Christianen, Miranda E M C; Bijl, Hendrik P; Schilstra, C; Langendijk, Johannes A

    2012-01-01

    PURPOSE: To apply recently developed predictive models for swallowing dysfunction to compare the predicted probabilities of swallowing dysfunction for standard intensity modulated radiotherapy (ST-IMRT) and swallowing sparing IMRT (SW-IMRT). MATERIALS AND METHODS: Thirty head and neck cancer patient

  6. Convex reformulation of biologically-based multi-criteria intensity-modulated radiation therapy optimization including fractionation effects.

    NARCIS (Netherlands)

    Hoffmann, A.L.; Hertog, D. den; Siem, A.Y.; Kaanders, J.H.A.M.; Huizenga, H.

    2008-01-01

    Finding fluence maps for intensity-modulated radiation therapy (IMRT) can be formulated as a multi-criteria optimization problem for which Pareto optimal treatment plans exist. To account for the dose-per-fraction effect of fractionated IMRT, it is desirable to exploit radiobiological treatment plan

  7. Fluorine-18-Labeled Fluoromisonidazole Positron Emission and Computed Tomography-Guided Intensity-Modulated Radiotherapy for Head and Neck Cancer: A Feasibility Study

    International Nuclear Information System (INIS)

    Purpose: Hypoxia renders tumor cells radioresistant, limiting locoregional control from radiotherapy (RT). Intensity-modulated RT (IMRT) allows for targeting of the gross tumor volume (GTV) and can potentially deliver a greater dose to hypoxic subvolumes (GTVh) while sparing normal tissues. A Monte Carlo model has shown that boosting the GTVh increases the tumor control probability. This study examined the feasibility of fluorine-18-labeled fluoromisonidazole positron emission tomography/computed tomography (18F-FMISO PET/CT)-guided IMRT with the goal of maximally escalating the dose to radioresistant hypoxic zones in a cohort of head and neck cancer (HNC) patients. Methods and Materials: 18F-FMISO was administered intravenously for PET imaging. The CT simulation, fluorodeoxyglucose PET/CT, and 18F-FMISO PET/CT scans were co-registered using the same immobilization methods. The tumor boundaries were defined by clinical examination and available imaging studies, including fluorodeoxyglucose PET/CT. Regions of elevated 18F-FMISO uptake within the fluorodeoxyglucose PET/CT GTV were targeted for an IMRT boost. Additional targets and/or normal structures were contoured or transferred to treatment planning to generate 18F-FMISO PET/CT-guided IMRT plans. Results: The heterogeneous distribution of 18F-FMISO within the GTV demonstrated variable levels of hypoxia within the tumor. Plans directed at performing 18F-FMISO PET/CT-guided IMRT for 10 HNC patients achieved 84 Gy to the GTVh and 70 Gy to the GTV, without exceeding the normal tissue tolerance. We also attempted to deliver 105 Gy to the GTVh for 2 patients and were successful in 1, with normal tissue sparing. Conclusion: It was feasible to dose escalate the GTVh to 84 Gy in all 10 patients and in 1 patient to 105 Gy without exceeding the normal tissue tolerance. This information has provided important data for subsequent hypoxia-guided IMRT trials with the goal of further improving locoregional control in HNC patients

  8. Reduced Toxicity With Intensity Modulated Radiation Therapy (IMRT) for Desmoplastic Small Round Cell Tumor (DSRCT): An Update on the Whole Abdominopelvic Radiation Therapy (WAP-RT) Experience

    Energy Technology Data Exchange (ETDEWEB)

    Desai, Neil B. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Stein, Nicholas F. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); LaQuaglia, Michael P. [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Alektiar, Kaled M. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Kushner, Brian H.; Modak, Shakeel; Magnan, Heather M. [Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Goodman, Karyn [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Wolden, Suzanne L., E-mail: woldens@mskcc.org [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

    2013-01-01

    Purpose: Desmoplastic small round cell tumor (DSRCT) is a rare malignancy typically involving the peritoneum in young men. Whole abdominopelvic radiation therapy (WAP-RT) using conventional 2-dimensional (2D) radiation therapy (RT) is used to address local recurrence but has been limited by toxicity. Our objectives were to assess the benefit of intensity modulated radiation therapy (IMRT) on toxicity and to update the largest series on radiation for DSRCT. Methods and Materials: The records of 31 patients with DSRCT treated with WAP-RT (22 with 2D-RT and 9 with IMRT) between 1992 and 2011 were retrospectively reviewed. All received multi-agent chemotherapy and maximal surgical debulking followed by 30 Gy of WAP-RT. A further focal boost of 12 to 24 Gy was used in 12 cases. Boost RT and autologous stem cell transplantation were nearly exclusive to patients treated with 2D-RT. Toxicities were assessed with the Common Terminology Criteria for Adverse Events. Dosimetric analysis compared IMRT and simulated 2D-RT dose distributions. Results: Of 31 patients, 30 completed WAP-RT, with a median follow-up after RT of 19 months. Acute toxicity was reduced with IMRT versus 2D-RT: P=.04 for gastrointestinal toxicity of grade 2 or higher (33% vs 77%); P=.02 for grade 4 hematologic toxicity (33% vs 86%); P=.01 for rates of granulocyte colony-stimulating factor; and P=.04 for rates of platelet transfusion. Post treatment red blood cell and platelet transfusion rates were also reduced (P=.01). IMRT improved target homogeneity ([D05-D95]/D05 of 21% vs 46%) and resulted in a 21% mean bone dose reduction. Small bowel obstruction was the most common late toxicity (23% overall). Updated 3-year overall survival and progression-free survival rates were 50% and 24%, respectively. Overall survival was associated with distant metastasis at diagnosis on multivariate analysis. Most failures remained intraperitoneal (88%). Conclusions: IMRT for consolidative WAP-RT in DSRCT improves

  9. Effect of Increasing Experience on Dosimetric and Clinical Outcomes in the Management of Malignant Pleural Mesothelioma With Intensity-Modulated Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Pretesh R., E-mail: patel073@mc.duke.edu [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Yoo, Sua [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Broadwater, Gloria [Cancer Center Biostatistics, Duke University Medical Center, Durham, North Carolina (United States); Marks, Lawrence B. [Department of Radiation Oncology, University of North Carolina, Chapel Hill, North Carolina (United States); Miles, Edward F. [Naval Medical Center, Portsmouth, Virginia (United States); D' Amico, Thomas A.; Harpole, David [Department of Surgery, Division of Thoracic Surgery, Duke University Medical Center, Durham, North Carolina (United States); Kelsey, Chris R. [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States)

    2012-05-01

    Purpose: To assess the impact of increasing experience with intensity-modulated radiation therapy (IMRT) after extrapleural pneumonectomy (EPP) for malignant pleural mesothelioma (MPM). Methods and Materials: The records of all patients who received IMRT following EPP at Duke University Medical Center between 2005 and 2010 were reviewed. Target volumes included the preoperative extent of the pleural space, chest wall incisions, involved nodal stations, and a boost to close/positive surgical margins if applicable. Patients were typically treated with 9-11 beams with gantry angles, collimator rotations, and beam apertures manually fixed to avoid the contalateral lung and to optimize target coverage. Toxicity was graded retrospectively using National Cancer Institute common toxicity criteria version 4.0. Target coverage and contralateral lung irradiation were evaluated over time by using linear regression. Local control, disease-free survival, and overall survival rates were estimated using the Kaplan-Meier method. Results: Thirty patients received IMRT following EPP; 21 patients also received systemic chemotherapy. Median follow-up was 15 months. The median dose prescribed to the entire ipsilateral hemithorax was 45 Gy (range, 40-50.4 Gy) with a boost of 8-25 Gy in 9 patients. Median survival was 23.2 months. Two-year local control, disease-free survival, and overall survival rates were 47%, 34%, and 50%, respectively. Increasing experience planning MPM cases was associated with improved coverage of planning target volumes (P=.04). Similarly, mean lung dose (P<.01) and lung V5 (volume receiving 5 Gy or more; P<.01) values decreased with increasing experience. Lung toxicity developed after IMRT in 4 (13%) patients at a median of 2.2 months after RT (three grade 3-4 and one grade 5). Lung toxicity developed in 4 of the initial 15 patients vs none of the last 15 patients treated. Conclusions: With increasing experience, target volume coverage improved and dose to the

  10. Effect of Increasing Experience on Dosimetric and Clinical Outcomes in the Management of Malignant Pleural Mesothelioma With Intensity-Modulated Radiation Therapy

    International Nuclear Information System (INIS)

    Purpose: To assess the impact of increasing experience with intensity-modulated radiation therapy (IMRT) after extrapleural pneumonectomy (EPP) for malignant pleural mesothelioma (MPM). Methods and Materials: The records of all patients who received IMRT following EPP at Duke University Medical Center between 2005 and 2010 were reviewed. Target volumes included the preoperative extent of the pleural space, chest wall incisions, involved nodal stations, and a boost to close/positive surgical margins if applicable. Patients were typically treated with 9-11 beams with gantry angles, collimator rotations, and beam apertures manually fixed to avoid the contalateral lung and to optimize target coverage. Toxicity was graded retrospectively using National Cancer Institute common toxicity criteria version 4.0. Target coverage and contralateral lung irradiation were evaluated over time by using linear regression. Local control, disease-free survival, and overall survival rates were estimated using the Kaplan-Meier method. Results: Thirty patients received IMRT following EPP; 21 patients also received systemic chemotherapy. Median follow-up was 15 months. The median dose prescribed to the entire ipsilateral hemithorax was 45 Gy (range, 40-50.4 Gy) with a boost of 8-25 Gy in 9 patients. Median survival was 23.2 months. Two-year local control, disease-free survival, and overall survival rates were 47%, 34%, and 50%, respectively. Increasing experience planning MPM cases was associated with improved coverage of planning target volumes (P=.04). Similarly, mean lung dose (P<.01) and lung V5 (volume receiving 5 Gy or more; P<.01) values decreased with increasing experience. Lung toxicity developed after IMRT in 4 (13%) patients at a median of 2.2 months after RT (three grade 3-4 and one grade 5). Lung toxicity developed in 4 of the initial 15 patients vs none of the last 15 patients treated. Conclusions: With increasing experience, target volume coverage improved and dose to the

  11. A nested partitions framework for beam angle optimization in intensity-modulated radiation therapy

    International Nuclear Information System (INIS)

    Coupling beam angle optimization with dose optimization in intensity-modulated radiation therapy (IMRT) increases the size and complexity of an already large-scale combinatorial optimization problem. We have developed a novel algorithm, nested partitions (NP), that is capable of finding suitable beam angle sets by guiding the dose optimization process. NP is a metaheuristic that is flexible enough to guide the search of a heuristic or deterministic dose optimization algorithm. The NP method adaptively samples from the entire feasible region, or search space, and coordinates the sampling effort with a systematic partitioning of the feasible region at successive iterations, concentrating the search in promising subsets. We used a 'warm-start' approach by initiating NP with beam angle samples derived from an integer programming (IP) model. In this study, we describe our implementation of the NP framework with a commercial optimization algorithm. We compared the NP framework with equi-spaced beam angle selection, the IP method, greedy heuristic and random sampling heuristic methods. The results of the NP approach were evaluated using two clinical cases (head and neck and whole pelvis) involving the primary tumor and nodal volumes. Our results show that NP produces better quality solutions than the alternative considered methods

  12. Intensity-Modulated Radiotherapy in Postoperative Treatment of Oral Cavity Cancers

    International Nuclear Information System (INIS)

    Purpose: To present our single-institution experience of intensity-modulated radiotherapy (IMRT) for oral cavity cancer. Methods and Materials: Between September 2000 and December 2006, 35 patients with histologically confirmed squamous cell carcinoma of the oral cavity underwent surgery followed by postoperative IMRT. The sites included were buccal mucosa in 8, oral tongue in 11, floor of the mouth in 9, gingiva in 4, hard palate in 2, and retromolar trigone in 1. Most patients had Stage III-IV disease (80%). Ten patients (29%) also received concurrent postoperative chemotherapy with IMRT. The median prescribed radiation dose was 60 Gy. Results: The median follow-up for surviving patients was 28.1 months (range, 11.9-85.1). Treatment failure occurred in 11 cases as follows: local in 4, regional in 2, and distant metastases in 5. Of the 5 patients with distant metastases, 2 presented with dermal metastases. The 2- and 3-year estimates of locoregional progression-free survival, distant metastasis-free survival, disease-free survival, and overall survival were 84% and 77%, 85% and 85%, 70% and 64%, and 74% and 74%, respectively. Acute Grade 2 or greater dermatitis, mucositis, and esophageal reactions were experienced by 54%, 66%, and 40% of the patients, respectively. Documented late complications included trismus (17%) and osteoradionecrosis (5%). Conclusion: IMRT as an adjuvant treatment after surgical resection for oral cavity tumors is feasible and effective, with promising results and acceptable toxicity

  13. Design and Fabrication of TES Detector Modules for the TIME-Pilot [CII] Intensity Mapping Experiment

    Science.gov (United States)

    Hunacek, J.; Bock, J.; Bradford, C. M.; Bumble, B.; Chang, T.-C.; Cheng, Y.-T.; Cooray, A.; Crites, A.; Hailey-Dunsheath, S.; Gong, Y.; Kenyon, M.; Koch, P.; Li, C.-T.; O'Brient, R.; Shirokoff, E.; Shiu, C.; Staniszewski, Z.; Uzgil, B.; Zemcov, M.

    2016-08-01

    We are developing a series of close-packed modular detector arrays for TIME-Pilot, a new mm-wavelength grating spectrometer array that will map the intensity fluctuations of the redshifted 157.7 \\upmu m emission line of singly ionized carbon ([CII]) from redshift z ˜ 5 to 9. TIME-Pilot's two banks of 16 parallel-plate waveguide spectrometers (one bank per polarization) will have a spectral range of 183-326 GHz and a resolving power of R ˜ 100. The spectrometers use a curved diffraction grating to disperse and focus the light on a series of output arcs, each sampled by 60 transition edge sensor (TES) bolometers with gold micro-mesh absorbers. These low-noise detectors will be operated from a 250 mK base temperature and are designed to have a background-limited NEP of {˜ }10^{-17} mathrm {W}/mathrm {Hz}^{1/2}. This proceeding presents an overview of the detector design in the context of the TIME-Pilot instrument. Additionally, a prototype detector module produced at the Microdevices Laboratory at JPL is shown.

  14. Accounting for range uncertainties in the optimization of intensity modulated proton therapy.

    Science.gov (United States)

    Unkelbach, Jan; Chan, Timothy C Y; Bortfeld, Thomas

    2007-05-21

    Treatment plans optimized for intensity modulated proton therapy (IMPT) may be sensitive to range variations. The dose distribution may deteriorate substantially when the actual range of a pencil beam does not match the assumed range. We present two treatment planning concepts for IMPT which incorporate range uncertainties into the optimization. The first method is a probabilistic approach. The range of a pencil beam is assumed to be a random variable, which makes the delivered dose and the value of the objective function a random variable too. We then propose to optimize the expectation value of the objective function. The second approach is a robust formulation that applies methods developed in the field of robust linear programming. This approach optimizes the worst case dose distribution that may occur, assuming that the ranges of the pencil beams may vary within some interval. Both methods yield treatment plans that are considerably less sensitive to range variations compared to conventional treatment plans optimized without accounting for range uncertainties. In addition, both approaches--although conceptually different--yield very similar results on a qualitative level. PMID:17473350

  15. Intensity-modulated radiation therapy to bilateral lower limb extremities concurrently: a planning case study

    International Nuclear Information System (INIS)

    Non-melanomatous skin cancers represent 80% of all newly diagnosed cancers in Australia with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) being the most common. A previously healthy 71-year-old woman presented with widespread and tender superficial skin cancers on the lower bilateral limbs. External beam radiation therapy through the use of intensity-modulated radiation therapy (IMRT) was employed as the treatment modality of choice as this technique provides conformal dose distribution to a three-dimensional treatment volume while reducing toxicity to surrounding tissues. The patient was prescribed a dose of 60 Gy to the planning target volume (PTV) with 1.0 cm bolus over the ventral surface of each limb. The beam arrangement consisted of six treatment fields that avoided entry and exit through the contralateral limb. The treatment plans met the International Commission on Radiation Units and Measurements (ICRU) guidelines and produced highly conformal dosimetric results. Skin toxicity was measured against the National Cancer Institute: Common Terminology Criteria for Adverse Events (NCI: CTCAE) version 3. A well-tolerated treatment was delivered with excellent results given the initial extent of the disease. This case study has demonstrated the feasibility and effectiveness of IMRT for skin cancers as an alternative to surgery and traditional superficial radiation therapy, utilising a complex PTV of the extremities for patients with similar presentations

  16. Risk of secondary cancers from scattered radiation during intensity-modulated radiotherapies for hepatocellular carcinoma

    International Nuclear Information System (INIS)

    To evaluate and compare the risks of secondary cancers from therapeutic doses received by patients with hepatocellular carcinoma (HCC) during intensity-modulated radiotherapy (IMRT), volumetric arc therapy (VMAT), and tomotherapy (TOMO). Treatments for five patients with hepatocellular carcinoma (HCC) were planned using IMRT, VMAT, and TOMO. Based on the Biological Effects of Ionizing Radiation VII method, the excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) were evaluated from therapeutic doses, which were measured using radiophotoluminescence glass dosimeters (RPLGDs) for each organ inside a humanoid phantom. The average organ equivalent doses (OEDs) of 5 patients were measured as 0.23, 1.18, 0.91, 0.95, 0.97, 0.24, and 0.20 Gy for the thyroid, lung, stomach, liver, small intestine, prostate (or ovary), and rectum, respectively. From the OED measurements, LAR incidence were calculated as 83, 46, 22, 30, 2 and 6 per 104 person for the lung, stomach, normal liver, small intestine, prostate (or ovary), and rectum. We estimated the secondary cancer risks at various organs for patients with HCC who received different treatment modalities. We found that HCC treatment is associated with a high secondary cancer risk in the lung and stomach

  17. Intensity modulated radiotherapy with concurrent chemotherapy for larynx preservation of advanced resectable hypopharyngeal cancer

    Directory of Open Access Journals (Sweden)

    Chao Hsing-Lung

    2010-05-01

    Full Text Available Abstract Background To analyze the rate of larynx preservation in patients of locally advanced hypopharyngeal cancer treated with intensity modulated radiotherapy (IMRT plus concurrent chemotherapy, and compare the results with patients treated with primary surgery. Methods Between January 2003 and November 2007, 14 patients were treated with primary surgery and 33 patients were treated with concurrent chemoradiotherapy (CCRT using IMRT technique. Survival rate, larynx preservation rate were calculated with the Kaplan-Meier method. Multivariate analysis was conducted for significant prognostic factors with Cox-regression method. Results The median follow-up was 19.4 months for all patients, and 25.8 months for those alive. The 5-year overall survival rate was 33% and 44% for primary surgery and definitive CCRT, respectively (p = 0.788. The 5-year functional larynx-preservation survival after IMRT was 40%. Acute toxicities were common, but usually tolerable. The rates of treatment-related mucositis (≥ grade 2 and pharyngitis (≥ grade 3 were higher in the CCRT group. For multivariate analysis, treatment response and cricoid cartilage invasion strongly correlated with survival. Conclusions IMRT plus concurrent chemotherapy may preserve the larynx without compromising survival. Further studies on new effective therapeutic agents are essential.

  18. Intensity modulated radiotherapy with concurrent chemotherapy for larynx preservation of advanced resectable hypopharyngeal cancer

    International Nuclear Information System (INIS)

    To analyze the rate of larynx preservation in patients of locally advanced hypopharyngeal cancer treated with intensity modulated radiotherapy (IMRT) plus concurrent chemotherapy, and compare the results with patients treated with primary surgery. Between January 2003 and November 2007, 14 patients were treated with primary surgery and 33 patients were treated with concurrent chemoradiotherapy (CCRT) using IMRT technique. Survival rate, larynx preservation rate were calculated with the Kaplan-Meier method. Multivariate analysis was conducted for significant prognostic factors with Cox-regression method. The median follow-up was 19.4 months for all patients, and 25.8 months for those alive. The 5-year overall survival rate was 33% and 44% for primary surgery and definitive CCRT, respectively (p = 0.788). The 5-year functional larynx-preservation survival after IMRT was 40%. Acute toxicities were common, but usually tolerable. The rates of treatment-related mucositis (≥ grade 2) and pharyngitis (≥ grade 3) were higher in the CCRT group. For multivariate analysis, treatment response and cricoid cartilage invasion strongly correlated with survival. IMRT plus concurrent chemotherapy may preserve the larynx without compromising survival. Further studies on new effective therapeutic agents are essential

  19. Automation of the solution type of intensity modulated radiation therapy with direct planning neoplastic breast lesions

    International Nuclear Information System (INIS)

    Breast cancer ranks first among the lesions malignancies involving the Cuban women and the second in mortality only surpassed by lung injury. The breast-conserving surgery is becoming less appeal, with an increase in the choice of radiotherapy to the breast operated, and the surgical bed. Intensity Modulated Radiation Therapy, IMRT has demonstrated better results in the dose distribution for irradiation dimensional treatment breast shaping, 3DCRT. We developed a MATLAB application to obtain the solution type to direct planning IMRT for breast neoplasm. The technique was implemented in the Planning System Treatment Plus Theraplan v3.8 and Precise1 ELEKTA linear accelerator. Static segments are constructed for each portal of incidence and Excel files are exported as the positions of the blades. The technique was validated with a patient, which he performed a radiographic study of computerized axial tomography planning purposes. The standard solution built is consistent with those reported internationally and consists of a segment type and at least two segments of type B. The assignment of the relative weights of the segments is done manually by trial and error procedure, with the general rule of 90% by weight assigned to segment A and the remaining 10% divided equally between B-type segments IMRT breast obtained in a dose 17% homogeneity better than 3DCRT and reduced the average dose in the lung ipsilateral 15%. (author)

  20. Improved Beam Angle Arrangement in Intensity Modulated Proton Therapy Treatment Planning for Localized Prostate Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Wenhua; Lim, Gino J. [Department of Industrial Engineering, University of Houston, Houston, TX 77204 (United States); Li, Yupeng [Applied Research, Varian Medical Systems, Palo Alto, CA 94304 (United States); Zhu, X. Ronald; Zhang, Xiaodong, E-mail: xizhang@mdanderson.org [Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030 (United States)

    2015-03-30

    Purpose: This study investigates potential gains of an improved beam angle arrangement compared to a conventional fixed gantry setup in intensity modulated proton therapy (IMPT) treatment for localized prostate cancer patients based on a proof of principle study. Materials and Methods: Three patients with localized prostate cancer retrospectively selected from our institution were studied. For each patient, IMPT plans were designed using two, three and four beam angles, respectively, obtained from a beam angle optimization algorithm. Those plans were then compared with ones using two lateral parallel-opposed beams according to the conventional planning protocol for localized prostate cancer adopted at our institution. Results: IMPT plans with two optimized angles achieved significant improvements in rectum sparing and moderate improvements in bladder sparing against those with two lateral angles. Plans with three optimized angles further improved rectum sparing significantly over those two-angle plans, whereas four-angle plans found no advantage over three-angle plans. A possible three-beam class solution for localized prostate patients was suggested and demonstrated with preserved dosimetric benefits because individually optimized three-angle solutions were found sharing a very similar pattern. Conclusions: This study has demonstrated the potential of using an improved beam angle arrangement to better exploit the theoretical dosimetric benefits of proton therapy and provided insights of selecting quality beam angles for localized prostate cancer treatment.

  1. Improved Beam Angle Arrangement in Intensity Modulated Proton Therapy Treatment Planning for Localized Prostate Cancer

    Directory of Open Access Journals (Sweden)

    Wenhua Cao

    2015-03-01

    Full Text Available Purpose: This study investigates potential gains of an improved beam angle arrangement compared to a conventional fixed gantry setup in intensity modulated proton therapy (IMPT treatment for localized prostate cancer patients based on a proof of principle study. Materials and Methods: Three patients with localized prostate cancer retrospectively selected from our institution were studied. For each patient, IMPT plans were designed using two, three and four beam angles, respectively, obtained from a beam angle optimization algorithm. Those plans were then compared with ones using two lateral parallel-opposed beams according to the conventional planning protocol for localized prostate cancer adopted at our institution. Results: IMPT plans with two optimized angles achieved significant improvements in rectum sparing and moderate improvements in bladder sparing against those with two lateral angles. Plans with three optimized angles further improved rectum sparing significantly over those two-angle plans, whereas four-angle plans found no advantage over three-angle plans. A possible three-beam class solution for localized prostate patients was suggested and demonstrated with preserved dosimetric benefits because individually optimized three-angle solutions were found sharing a very similar pattern. Conclusions: This study has demonstrated the potential of using an improved beam angle arrangement to better exploit the theoretical dosimetric benefits of proton therapy and provided insights of selecting quality beam angles for localized prostate cancer treatment.

  2. Improved Beam Angle Arrangement in Intensity Modulated Proton Therapy Treatment Planning for Localized Prostate Cancer

    International Nuclear Information System (INIS)

    Purpose: This study investigates potential gains of an improved beam angle arrangement compared to a conventional fixed gantry setup in intensity modulated proton therapy (IMPT) treatment for localized prostate cancer patients based on a proof of principle study. Materials and Methods: Three patients with localized prostate cancer retrospectively selected from our institution were studied. For each patient, IMPT plans were designed using two, three and four beam angles, respectively, obtained from a beam angle optimization algorithm. Those plans were then compared with ones using two lateral parallel-opposed beams according to the conventional planning protocol for localized prostate cancer adopted at our institution. Results: IMPT plans with two optimized angles achieved significant improvements in rectum sparing and moderate improvements in bladder sparing against those with two lateral angles. Plans with three optimized angles further improved rectum sparing significantly over those two-angle plans, whereas four-angle plans found no advantage over three-angle plans. A possible three-beam class solution for localized prostate patients was suggested and demonstrated with preserved dosimetric benefits because individually optimized three-angle solutions were found sharing a very similar pattern. Conclusions: This study has demonstrated the potential of using an improved beam angle arrangement to better exploit the theoretical dosimetric benefits of proton therapy and provided insights of selecting quality beam angles for localized prostate cancer treatment

  3. Image-guided intensity modulated radiotherapy with chemotherapy for postoperative esophageal cancer patients with regional relapse

    International Nuclear Information System (INIS)

    The objective of this study is to evaluate the efficacy and morbidity of image-guided mage-Guided Intensity Modulated Radiotherapy with chemotherapy for postoperative esophageal cancer patients with regional relapse. Between April 2010 and July 2013, 21 patients who previously treated with radical surgery were irradiated with Novalis Tx for regional relapse. Twenty-eight lesions were treated with IG-IMRT with chemotherapy. Seven patients have already had chemoradiotherapy for preoperative or salvage intervention. The median dose of radiation was 66 Gy/4.5 weeks. Nineteen patients had received the pre/post operative chemo (radio) therapy (standard FP). Three patients refused chemotherapy and 18 patients have received concomitant weekly DOC + CDGP chemotherapy. The responses were evaluated according to RECIST criteria. Acute toxicities were evaluated according to CTCAE 3.0 criteria. Median follow-up was 18 months (3 to 42 months). The initial response rate and CR rate was 89% and 61%, respectively. The actuarial 3-year survival rate was 71%. Acute toxicity was limited to grade 2 toxicity including anorexia (14%), pain (25%) and leukopenia (25%). More than G2 late toxicity has not observed. IG-IMRT with chemotherapy can offer a short and well-tolerated treatment for regional relapse after radically operated patients. Efficacy and toxicity need to be evaluated over the long term, but initial results are encouraging. (author)

  4. Flow angle dependent photoacoustic Doppler power spectra under intensity-modulated continuous wave laser excitation

    Directory of Open Access Journals (Sweden)

    Yu Tong

    2016-02-01

    Full Text Available Photoacoustic Doppler (PAD power spectra showing an evident Doppler shift represent the major characteristics of the continuous wave-excited or burst wave-excited versions of PAD flow measurements. In this paper, the flow angle dependences of the PAD power spectra are investigated using an experiment setup that was established based on intensity-modulated continuous wave laser excitation. The setup has an overall configuration that is similar to a previously reported configuration, but is more sophisticated in that it accurately aligns the laser illumination with the ultrasound detection process, and in that it picks up the correct sample position. In the analysis of the power spectra data, we find that the background power spectra can be extracted by combining the output signals from the two channels of the lock-in amplifier, which is very useful for identification of the PAD power spectra. The power spectra are presented and analyzed in opposite flow directions, at different flow speeds, and at different flow angles. The power spectra at a 90° flow angle show the unique properties of symmetrical shapes due to PAD broadening. For the other flow angles, the smoothed power spectra clearly show a flow angle cosine relationship.

  5. SU-E-P-18: Intensity-Modulated Radiation Therapy for Cervical Esophageal Squamous Cell Carcinoma

    International Nuclear Information System (INIS)

    Purpose: To retrospectively analyze the outcomes and prognostic factors of cervical esophageal squamous cell carcinoma (SCC) treated with intensity modulated radiation therapy (IMRT). Methods: Thirty-seven patients with cervical esophageal SCC treated with IMRT were analyzed retrospectively. They received 54–66 Gy in 27–32 fractions. Nineteen patients received concurrent (n=12) or sequential (n=7) platinum-based two drugs chemoradiotherapy. Overall survival (OS), local control rates (LCR) and prognostic factors were evaluated. Acute toxicities and patterns of first failures were observed. Results: The median follow-up was 46 months for alive patients. The l-, 3-, 4- and 5-year OS of the all patients were 83.8%, 59.1%, 47.5% and 32.6% respectively. The median survival time was 46 months. The l-, 3-,4- and 5-year LCR were 82.9%, 63.0%, 54.5% and 54.5%, respectively. Univariate and Multivariate analysis all showed that size of GTV was an independent prognostic factor (p=0.033, p=0.039). There were no patients with Grade 3 acute radiation esophagitis and Grade 2–4 acute pneumonitis. The local failure accounted for 70.0% of all treatment-related failures. Conclusion: IMRT is safe and effective in the treatment of cervical esophageal squamous cell carcinoma. Size of GTV is an independent prognostic factor. Local failure still remains the main reason of treatment failures. The authors declare no conflicts of interest in preparing this article

  6. A methodology for automatic intensity-modulated radiation treatment planning for lung cancer

    Science.gov (United States)

    Zhang, Xiaodong; Li, Xiaoqiang; Quan, Enzhuo M.; Pan, Xiaoning; Li, Yupeng

    2011-07-01

    In intensity-modulated radiotherapy (IMRT), the quality of the treatment plan, which is highly dependent upon the treatment planner's level of experience, greatly affects the potential benefits of the radiotherapy (RT). Furthermore, the planning process is complicated and requires a great deal of iteration, and is often the most time-consuming aspect of the RT process. In this paper, we describe a methodology to automate the IMRT planning process in lung cancer cases, the goal being to improve the quality and consistency of treatment planning. This methodology (1) automatically sets beam angles based on a beam angle automation algorithm, (2) judiciously designs the planning structures, which were shown to be effective for all the lung cancer cases we studied, and (3) automatically adjusts the objectives of the objective function based on a parameter automation algorithm. We compared treatment plans created in this system (mdaccAutoPlan) based on the overall methodology with plans from a clinical trial of IMRT for lung cancer run at our institution. The 'autoplans' were consistently better, or no worse, than the plans produced by experienced medical dosimetrists in terms of tumor coverage and normal tissue sparing. We conclude that the mdaccAutoPlan system can potentially improve the quality and consistency of treatment planning for lung cancer.

  7. Development of a quality control system in intensity modulated radiotherapy (IMRT)

    International Nuclear Information System (INIS)

    The more complex the technique of radiotherapy is, the more refined the quality control must be. The technique of Intensity Modulated Radiotherapy (IMRT) is one of the technological innovations that gained space in the whole worlds in the last decade whose parameters of quality control are not fully established yet. The present work developed a phantom for quality control in IMRT to be implemented in the routine of the Radiotherapy Quality Control Program (PQRT) of the Brazilian National Cancer Institute (INCa). The device consists of a block formed by several polystyrene slice with TDLs and radiochromic film inserted. It should be sent (or taken) to the Program participating institutions to be irradiated under certain conditions and then be returned to the PQRT., where the discrepancy degree between the planned treatment and those effectively delivered will be evaluated. The system was validated through the test cases and the pilot program preformed in nine radiotherapy centers that perform IMRT in the southeast region of Brazil. (author)

  8. Including robustness in multi-criteria optimization for intensity-modulated proton therapy

    CERN Document Server

    Chen, Wei; Trofimov, Alexei; Madden, Thomas; Kooy, Hanne; Bortfeld, Thomas; Craft, David

    2011-01-01

    We present a method to include robustness into a multi-criteria optimization (MCO) framework for intensity-modulated proton therapy (IMPT). The approach allows one to simultaneously explore the trade-off between different objectives as well as the trade-off between robustness and nominal plan quality. In MCO, a database of plans each emphasizing different treatment planning objectives, is pre-computed to approximate the Pareto surface. An IMPT treatment plan that strikes the best balance between the different objectives can be selected by navigating on the Pareto surface. In our approach, robustness is integrated into MCO by adding robustified objectives and constraints to the MCO problem. Uncertainties of the robust problem are modeled by pre-calculated dose-influence matrices for a nominal scenario and a number of pre-defined error scenarios. A robustified objective represents the worst objective function value that can be realized for any of the error scenarios. The optimization method is based on a linear...

  9. Risk of second cancer from scattered radiation of intensity-modulated radiotherapies with lung cancer

    International Nuclear Information System (INIS)

    To compare the risk of secondary cancer from scattered and leakage doses following intensity-modulated radiotherapy (IMRT), volumetric arc therapy (VMAT) and tomotherapy (TOMO) in patients with lung cancer. IMRT, VMAT and TOMO were planned for five lung cancer patients. Organ equivalent doses (OEDs) are estimated from the measured corresponding secondary doses during irradiation at various points 20 to 80 cm from the iso-center by using radio-photoluminescence glass dosimeter (RPLGD). The secondary dose per Gy from IMRT, VMAT and TOMO for lung cancer, measured 20 to 80 cm from the iso-center, are 0.02~2.03, 0.03~1.35 and 0.04~0.46 cGy, respectively. The mean values of relative OED of secondary dose of VMAT and TOMO, which is normalized by IMRT, ranged between 88.63% and 41.59% revealing 88.63% and 41.59% for thyroid, 82.33% and 41.85% for pancreas, 77.97% and 49.41% for bowel, 73.42% and 72.55% for rectum, 74.16% and 81.51% for prostate. The secondary dose and OED from TOMO became similar to those from IMRT and VMAT as the distance from the field edge increased. OED based estimation suggests that the secondary cancer risk from TOMO is less than or comparable to the risks from conventional IMRT and VMAT

  10. Dosimetric evaluation of compensation in radiotherapy of the breast: MLC intensity modulation and physical compensators

    International Nuclear Information System (INIS)

    Background and purpose: Electronic portal images may be used to design the compensation required to maximise dose uniformity in the breast from opposed tangential beams. Materials and methods: Four methods of implementing the desired compensation have been studied: a simple wedge, a physical compensator in conjunction with a wedge; one open field plus four shaped multi-leaf-collimated (MLC) fields, and one wedged field in conjunction with three shaped MLC fields. Evaluation was performed using thermoluminescent dosimeters (TLDs) placed inside a phantom which was designed to mimic the human breast. The measured results are compared with both the prediction of the in-house compensation design software and with the dose predicted by the GE Target II planning system. The implications of each method for the time taken to plan and deliver treatment were analysed. Results: The dose inhomogeneity, as measured at seven points in the central plane was greatest for the simple wedge (root mean square (rms) = 4.5%) compared to an open field plus four shaped MLC fields (rms = 2.2%), a wedged field plus three shaped MLC fields (rms = 3.3%), and the physical compensator (rms = 2.4%). The times required to plan and prepare these treatments varied considerably. The standard wedged treatment required under 15 min; both MLC-based and the physical compensator treatments required = 50 min. Differences of treatment delivery times were up to 8 min. Conclusions: These results indicate that the dose inhomogeneity can be reduced by beam intensity modulation designed using EPIDs

  11. Dosimetric comparison of tools for intensity modulated radiation therapy with gamma analysis: a phantom study

    Directory of Open Access Journals (Sweden)

    Akbas Ugur

    2015-01-01

    Full Text Available Dosimetry of the Intensity Modulated Radiation Therapy (IMRT is very important because of the complex dose distributions. Diode arrays are the most common and practical measurement tools for clinical usage for IMRT. Phantom selection is critical for QA process. IMRT treatment plans are recalculated for the phantom irradiation in QA. Phantoms are made in different geometrical shapes to measure the doses of different types of irradiation techniques. Comparison of measured and calculated dose distributions for IMRT can be made by using gamma analysis. In this study, 10 head-and-neck IMRT QA plans were created with Varian Eclipse 8.9 treatment planning system. Water equivalent RW3-slab phantoms, Octavius-2 phantom and PTW Seven29 2D-array were used for QA measurements. Gantry, collimator and couch positions set to 00 and QA plans were delivered to RW3 and Octavius phantoms. Then the positions set to original angles and QA plans irradiated again. Measured and calculated fluence maps were evaluated with gamma analysis for different DD and DTA criteria. The effect of different set-up conditions for RW3 and Octavius phantoms in QA plan delivery evaluated by gamma analysis. Results of gamma analysis show that using RW3-slab phantoms with setting parameters to 00 is more appropriate for IMRT QA.

  12. Comparison of optimization algorithms in intensity-modulated radiation therapy planning

    Science.gov (United States)

    Kendrick, Rachel

    Intensity-modulated radiation therapy is used to better conform the radiation dose to the target, which includes avoiding healthy tissue. Planning programs employ optimization methods to search for the best fluence of each photon beam, and therefore to create the best treatment plan. The Computational Environment for Radiotherapy Research (CERR), a program written in MATLAB, was used to examine some commonly-used algorithms for one 5-beam plan. Algorithms include the genetic algorithm, quadratic programming, pattern search, constrained nonlinear optimization, simulated annealing, the optimization method used in Varian EclipseTM, and some hybrids of these. Quadratic programing, simulated annealing, and a quadratic/simulated annealing hybrid were also separately compared using different prescription doses. The results of each dose-volume histogram as well as the visual dose color wash were used to compare the plans. CERR's built-in quadratic programming provided the best overall plan, but avoidance of the organ-at-risk was rivaled by other programs. Hybrids of quadratic programming with some of these algorithms seems to suggest the possibility of better planning programs, as shown by the improved quadratic/simulated annealing plan when compared to the simulated annealing algorithm alone. Further experimentation will be done to improve cost functions and computational time.

  13. Prognostic value of parapharyngeal extension in nasopharyngeal carcinoma treated with intensity modulated radiotherapy

    International Nuclear Information System (INIS)

    Background and purpose: The development of improved diagnostic and therapeutic techniques has revolutionized the management of nasopharyngeal carcinoma (NPC). The purpose of this study is to revaluate the prognostic value of parapharyngeal extension in NPC in the IMRT era. Material and methods: We retrospectively reviewed data from 749 biopsy-proven non-metastatic NPC patients. All patients were examined with magnetic resonance imaging (MRI) and received intensity-modulated radiotherapy (IMRT) as the primary treatment. Results: The incidence of parapharyngeal extension was 72.1%. A significant difference was observed in the disease-free survival (DFS; 70.3% vs. 89.1%, P < 0.001), distant metastasis-free survival (DMFS; 79.3% vs. 92.0%, P < 0.001), and local relapse-free survival (LRFS; 92.8% vs. 99.0%, P = 0.002) of patients with and without parapharyngeal extension. Parapharyngeal extension was an independent prognostic factor for DFS and DMFS in multivariate analysis (P = 0.001 and P = 0.015, respectively), but not LRFS. The difference between DMFS in patients with or without parapharyngeal space extension was statistically significant in patients with cervical lymph node metastasis (P < 0.001). Conclusions: In the IMRT era, parapharyngeal extension remains a poor prognosticator for DMFS in NPC, especially in patients with positive lymph node metastasis. Additional therapeutic improvements are required to achieve a favorable distant control in NPC with parapharyngeal extension

  14. A nested partitions framework for beam angle optimization in intensity-modulated radiation therapy

    Science.gov (United States)

    D'Souza, Warren D.; Zhang, Hao H.; Nazareth, Daryl P.; Shi, Leyuan; Meyer, Robert R.

    2008-06-01

    Coupling beam angle optimization with dose optimization in intensity-modulated radiation therapy (IMRT) increases the size and complexity of an already large-scale combinatorial optimization problem. We have developed a novel algorithm, nested partitions (NP), that is capable of finding suitable beam angle sets by guiding the dose optimization process. NP is a metaheuristic that is flexible enough to guide the search of a heuristic or deterministic dose optimization algorithm. The NP method adaptively samples from the entire feasible region, or search space, and coordinates the sampling effort with a systematic partitioning of the feasible region at successive iterations, concentrating the search in promising subsets. We used a 'warm-start' approach by initiating NP with beam angle samples derived from an integer programming (IP) model. In this study, we describe our implementation of the NP framework with a commercial optimization algorithm. We compared the NP framework with equi-spaced beam angle selection, the IP method, greedy heuristic and random sampling heuristic methods. The results of the NP approach were evaluated using two clinical cases (head and neck and whole pelvis) involving the primary tumor and nodal volumes. Our results show that NP produces better quality solutions than the alternative considered methods.

  15. Neutron intensity modulation and time-focusing with integrated Larmor and resonant frequency techniques

    Science.gov (United States)

    Zhao, Jinkui; Hamilton, William A.; Lee, Sung-Woo; Robertson, J. L.; Crow, Lowell; Kang, Yoon W.

    2015-09-01

    The analysis of neutron diffraction experiments often assumes that neutrons are elastically scattered from the sample. However, there is growing evidence that a significant fraction of the detected neutrons is in fact inelastically scattered, especially from soft materials and aqueous samples. Ignoring these inelastic contributions gives rise to inaccurate experimental results. To date, there has been no simple method with broad applicability for inelastic signal separation in neutron diffraction experiments. Here, we present a simple and robust method that we believe could be suited for this purpose. We use two radio frequency resonant spin flippers integrated with a Larmor precession field to modulate the neutron intensity and to encode the inelastic scattering information into the neutron data. All three components contribute to the spin encoding. The Larmor field serves several additional purposes. Its usage facilitates neutron time-focusing, eliminates the need for stringent magnetic shielding, and allows for compact setups. The scheme is robust, simple, and flexible. We believe that, with further improvements, it has the potential of adding inelastic signal discrimination capabilities to many existing diffraction instruments in the future.

  16. Adjuvant radiotherapy for gallbladder cancer: A dosimetric comparison of conformal radiotherapy and intensity-modulated radiotherapy

    Institute of Scientific and Technical Information of China (English)

    Xiao-Nan Sun; Qi Wang; Ben-Xing Gu; Yan-Hong Zhu; Jian-Bin Hu; Guo-Zhi Shi; Shu Zheng

    2011-01-01

    AIM: To assess the efficacy and toxicity of conformal radiotherapy (CRT) and compare with intensity-modulated radiotherapy (IMRT) in the treatment of gallbladder cancer.METHODS: Between November 2003 and January 2010, 20 patients with gallbladder cancer were treated with CRT with or without chemotherapy after surgical resection. Preliminary survival data were collected and examined using both Kaplan-Meier and actuarial analysis. Demographic and treatment parameters were collected. All patients were planned to receive 46-56 Gy in 1.8 or 2.0 Gy per fraction. CRT planning was compared with IMRT.RESULTS: The most common reported acute toxicities requiring medication (Radiation Therapy Oncology Group, Radiation Therapy Oncology Group Grade2) were nausea (10/20 patients) and diarrhea (3/20).There were no treatment-related deaths. Compared with CRT planning, IMRT significantly reduced the volume of right kidney receiving > 20 Gy and the volume of liver receiving > 30 Gy. IMRT has a negligible impact on the volume of left kidney receiving > 20 Gy. The 95% of prescribed dose for a planning tumor volume using either 3D CRT or IMRT planning were 84.0% ±6.7%, 82.9% ± 6.1%, respectively (P > 0.05).CONCLUSION: IMRT achieves similar excellent target coverage as compared with CRT planning, while reducingthe mean liver dose and volume above threshold dose. IMRT offers better sparing of the right kidney compared with CRT planning, with a significantly lower mean dose and volume above threshold dose.

  17. Intensity-modulated radiation therapy for head and neck cancer: Systematic review and meta-analysis

    International Nuclear Information System (INIS)

    Background and purpose: Intensity-modulated radiation therapy (IMRT) provides the possibility of dose-escalation with better normal tissue sparing. This study was performed to assess whether IMRT can improve clinical outcomes when compared with two-dimensional (2D-RT) or three-dimensional conformal radiation therapy (3D-CRT) in patients with head and neck cancer. Methods and materials: Only prospective phase III randomized trials comparing IMRT with 2D-RT or 3D-CRT were eligible. Combined surgery and/or chemotherapy were allowed. Two authors independently selected and assessed the studies regarding eligibility criteria and risk of bias. Results: Five studies were selected. A total of 871 patients were randomly assigned for 2D-RT or 3D-CRT (437), versus IMRT (434). Most patients presented with nasopharyngeal cancers (82%), and stages III/IV (62.1%). Three studies were classified as having unclear risk and two as high risk of bias. A significant overall benefit in favor of IMRT was found (hazard ratio – HR = 0.76; 95% CI: 0.66, 0.87; p < 0.0001) regarding xerostomia scores grade 2–4, with similar loco-regional control and overall survival. Conclusions: IMRT reduces the incidence of grade 2–4 xerostomia in patients with head and neck cancers without compromising loco-regional control and overall survival

  18. Meningioma Causing Visual Impairment: Outcomes and Toxicity After Intensity Modulated Radiation Therapy

    International Nuclear Information System (INIS)

    Purpose: To evaluate ophthalmologic outcomes and toxicity of intensity modulated radiation therapy (IMRT) in patients with meningiomas causing visual deficits. Methods and Materials: A prospective observational study with formal ophthalmologic and clinical assessment of 30 consecutive cases of meningioma affecting vision treated with IMRT from 2007 to 2011. Prescriptions were 50.4 Gy to mean target dose in 28 daily fractions. The median follow-up time was 28 months. Twenty-six meningiomas affected the anterior visual pathway (including 3 optic nerve sheath meningiomas); 4 were posterior to the chiasm. Results: Vision improved objectively in 12 patients (40%). Improvements were in visual field (5/16 patients), color vision (4/9 patients), acuity (1/15 patients), extraocular movements (3/11 patients), ptosis (1/5 patients), and proptosis (2/6 patients). No predictors of clinical response were found. Two patients had minor reductions in tumor dimensions on magnetic resonance imaging, 1 patient had radiological progression, and the other patients were stable. One patient experienced grade 2 keratitis, 1 patient had a minor visual field loss, and 5 patients had grade 1 dry eye. Conclusion: IMRT is an effective method for treating meningiomas causing ophthalmologic deficits, and toxicity is minimal. Thorough ophthalmologic assessment is important because clinical responses often occur in the absence of radiological change

  19. Improved genetic algorithm in optimization of beam orientation in intensity modulated radiotherapy

    International Nuclear Information System (INIS)

    Objective: At present beam orientation selection in intensity-modulated radiotherapy (IMRT) is mainly based on empiric knowledge. This study is to evaluate the feasibility of automated beam angle selection. Methods: Genetic algorithm technique which based on beam eye view dose measurement (BEVD-GA) was tested on two clinical cases, including a spine column cancer and a lung cancer. Three plans were obtained under the following different beam configurations: five equiangular-spaced beams, five beams with GA-selected, and five beams with BEVD-GA-selected beams. Then the dose distribution was compared among the three plans. Results: The method, restricting the range of genetic algorithm followed by carrying through genetic operations, not only shortened the optimization time, but also improved the optimization effect. For spine column cancer and lung cancer, the best IMRT plans were obtained with BEVD-GA-selected beams, which used automated beam orientation selection. Conclusions: Comparing with the conventional manual beam orientation selection, beam orientation optimization which is feasible in IMRT planning may significantly improve the efficiency and result. (authors)

  20. Validation of a track repeating algorithm for intensity modulated proton therapy: clinical cases study

    Science.gov (United States)

    Yepes, Pablo P.; Eley, John G.; Liu, Amy; Mirkovic, Dragan; Randeniya, Sharmalee; Titt, Uwe; Mohan, Radhe

    2016-04-01

    Monte Carlo (MC) methods are acknowledged as the most accurate technique to calculate dose distributions. However, due its lengthy calculation times, they are difficult to utilize in the clinic or for large retrospective studies. Track-repeating algorithms, based on MC-generated particle track data in water, accelerate dose calculations substantially, while essentially preserving the accuracy of MC. In this study, we present the validation of an efficient dose calculation algorithm for intensity modulated proton therapy, the fast dose calculator (FDC), based on a track-repeating technique. We validated the FDC algorithm for 23 patients, which included 7 brain, 6 head-and-neck, 5 lung, 1 spine, 1 pelvis and 3 prostate cases. For validation, we compared FDC-generated dose distributions with those from a full-fledged Monte Carlo based on GEANT4 (G4). We compared dose-volume-histograms, 3D-gamma-indices and analyzed a series of dosimetric indices. More than 99% of the voxels in the voxelized phantoms describing the patients have a gamma-index smaller than unity for the 2%/2 mm criteria. In addition the difference relative to the prescribed dose between the dosimetric indices calculated with FDC and G4 is less than 1%. FDC reduces the calculation times from 5 ms per proton to around 5 μs.

  1. Dose Verification in Intensity Modulation Radiation Therapy: A Fractal Dimension Characteristics Study

    Directory of Open Access Journals (Sweden)

    Jia-Ming Wu

    2013-01-01

    Full Text Available Purpose. This study describes how to identify the coincidence of desired planning isodose curves with film experimental results by using a mathematical fractal dimension characteristic method to avoid the errors caused by visual inspection in the intensity modulation radiation therapy (IMRT. Methods and Materials. The isodose curves of the films delivered by linear accelerator according to Plato treatment planning system were acquired using Osiris software to aim directly at a single interested dose curve for fractal characteristic analysis. The results were compared with the corresponding planning desired isodose curves for fractal dimension analysis in order to determine the acceptable confidence level between the planning and the measurement. Results. The film measured isodose curves and computer planning curves were deemed identical in dose distribution if their fractal dimensions are within some criteria which suggested that the fractal dimension is a unique fingerprint of a curve in checking the planning and film measurement results. The dose measured results of the film were presumed to be the same if their fractal dimension was within 1%. Conclusions. This quantitative rather than qualitative comparison done by fractal dimension numerical analysis helps to decrease the quality assurance errors in IMRT dosimetry verification.

  2. Retrospective Estimation of the Quality of Intensity-Modulated Radiotherapy Plans for Lung Cancer

    CERN Document Server

    Koo, Jihye; Chung, Weon Kuu; Kim, Dong Wook

    2015-01-01

    This study estimated the planning quality of intensity-modulated radiotherapy in 42 lung cancer cases to provide preliminary data for the development of a planning quality assurance algorithm. Organs in or near the thoracic cavity (ipsilateral lung, contralateral lung, heart, liver, esophagus, spinal cord, and bronchus) were selected as organs at risk (OARs). Radiotherapy plans were compared using the conformity index (CI), coverage index (CVI), and homogeneity index (HI) of the planning target volume (PTV), OAR-PTV distance and OAR-PTV overlap volume, and the V10Gy, V20Gy, and equivalent uniform dose (EUD) of the OARs. The CI, CVI, and HI of the PTV were 0.54 - 0.89 , 0.90 - 1.00 , and 0.11 - 0.41, respectively. The mean EUDs (V10Gy, V20Gy) of the ipsilateral lung, contralateral lung, esophagus, cord, liver, heart, and bronchus were 8.07 Gy (28.06, 13.17), 2.59 Gy (6.53, 1.18), 7.02 Gy (26.17, 12.32), 3.56 Gy (13.56, 4.48), 0.72 Gy (2.15, 0.91), 5.14 Gy (19.68, 8.62), and 10.56 Gy (36.08, 19.79), respectivel...

  3. Dosimetric evaluations of the interplay effect in respiratory-gated intensity-modulated radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Chen Hungcheng; Wu, Andrew; Brandner, Edward D.; Heron, Dwight E.; Huq, M. Saiful; Yue, Ning J.; Chen Wencheng [Department of Radiation Oncology, Helen F Graham Cancer Center, Christiana Care Health System, Newark, Delaware 19713 (United States); Department of Radiologic Sciences, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 (United States); Department of Radiation Oncology, University of Pittsburgh Medical Centers, Pittsburgh, Pennsylvania 15232 (United States); Cancer Institute of New Jersey, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, New Jersey 08903 (United States); Department of Radiation Oncology, Chiayi Chang Gung Memorial Hospital, Chiayi, Taiwan 61363 (China)

    2009-03-15

    The interplay between a mobile target and a dynamic multileaf collimator can compromise the accuracy of intensity-modulated radiation therapy (IMRT). Our goal in this study is to investigate the dosimetric effects caused by the respiratory motion during IMRT. A moving phantom was built to simulate the typical breathing motion. Different sizes of the gating windows were selected for gated deliveries. The residual motions during the beam-on period ranged from 0.5 to 3 cm. An IMRT plan with five treatment fields from different gantry angles were delivered to the moving phantom for three irradiation conditions: Stationary condition, moving with the use of gating system, and moving without the use of gating system. When the residual motion was 3 cm, the results showed significant differences in dose distributions between the stationary condition and the moving phantom without gating beam control. The overdosed or underdosed areas enclosed about 33% of the treatment area. In contrast, the dose distribution on the moving phantom with gating window set to 0.5 cm showed no significant differences from the stationary phantom. With the appropriate setting of the gating window, the deviation of dose from the respiratory motion can be minimized. It appeals that limiting the residual motion to less than 0.5 cm is critical for the treatments of mobile structures.

  4. Racial Differences in Diffusion of Intensity-Modulated Radiation Therapy for Localized Prostate Cancer.

    Science.gov (United States)

    Cobran, Ewan K; Chen, Ronald C; Overman, Robert; Meyer, Anne-Marie; Kuo, Tzy-Mey; O'Brien, Jonathon; Sturmer, Til; Sheets, Nathan C; Goldin, Gregg H; Penn, Dolly C; Godley, Paul A; Carpenter, William R

    2016-09-01

    Intensity-modulated radiation therapy (IMRT), an innovative treatment option for prostate cancer, has rapidly diffused over the past decade. To inform our understanding of racial disparities in prostate cancer treatment and outcomes, this study compared diffusion of IMRT in African American (AA) and Caucasian American (CA) prostate cancer patients during the early years of IMRT diffusion using the Surveillance, Epidemiology and End Results (SEER)-Medicare linked database. A retrospective cohort of 947 AA and 10,028 CA patients diagnosed with localized prostate cancer from 2002 through 2006, who were treated with either IMRT or non-IMRT as primary treatment within 1 year of diagnoses was constructed. Logistic regression was used to examine potential differences in diffusion of IMRT in AA and CA patients, while adjusting for socioeconomic and clinical covariates. A significantly smaller proportion of AA compared with CA patients received IMRT for localized prostate cancer (45% vs. 53%, p significance, as time and factors associated with race (socioeconomic, geographic, and tumor related factors) explained the preponderance of variance in use of IMRT. Further research examining improved access to innovative cancer treatment and technologies is essential to reducing racial disparities in cancer care. PMID:25657192

  5. Treatment of folliculitis decalvans using intensity-modulated radiation via tomotherapy

    International Nuclear Information System (INIS)

    Folliculitis decalvans (FD) is a form of primary neutrophilic scarring alopecia that is characterized clinically by chronic suppurative folliculitis and often associated with pruritus or even pain. Treatment of FD is often difficult. Herein, we report a case of recalcitrant and painful folliculitis decalvans refractory to antibiotic and anti-inflammatory therapies, which was successfully treated by intensity-modulated radiotherapy (IMRT) in order to irreversibly eliminate hair follicles that prove to be one etiological trigger. A 45-year-old male patient with a refractory FD presented with a crusting suppurative folliculitis and atrophic scarring patches on the scalp associated with pain and pruritus. We attempted relief of symptoms by reducing scalp inflammation and eliminating hair follicles through radiation. We delivered 11.0 Gy in two radiation series using tomotherapy, 5.0 Gy in 5 equivalent fractions as a first radiation course. The symptoms markedly decreased but did not totally disappear. Therefore, we delivered a second radiation series 4 months later with an additional 6 Gy. This led to almost complete epilation on the scalp and abolished pain and pruritus on the capillitium. The patient was regularly followed up until 26 months after radiotherapy. Draining lesions or exudation did not recur. He only experienced discrete hair regrowth in the occipital region with folliculitis 12 months after radiotherapy. These residual lesions are currently treated with laser epilation therapy. A radical approach to eliminating hair follicles by repeated radiation therapy may induce lasting relief of symptoms in chronic suppurative FD associated with persistent trichodynia. (orig.)

  6. Improved delivery efficiency for step and shoot intensity modulated radiotherapy using a fast-tuning magnetron

    International Nuclear Information System (INIS)

    The delivery efficiency of step and shoot intensity modulated radiotherapy (IMRT) has been improved by the installation of fast-tuning magnetrons into three travelling wave linear accelerators. The IMRT delivery efficiency and the beam start-up performance have been compared before and after installation. Start-up and inter sub-field times were reduced by an average of 3.0 s. A typical start-up time from depression of the start button to beam on is now around 4 s. Delivery efficiency for a variety of clinical and quality control prescriptions was improved by an average of 30.7% (range 7.4-60.9%), depending on a complex combination of the number of sub-fields, distance moved by leaves and dose rate. For the oldest accelerator (7 years old), dosimetric accuracy was significantly improved for low dose sub-fields. The dose output was within 2% for a 1 monitor unit (MU) sub-field and 1% for a 2 MU sub-field. The two newer accelerators displayed similar or better dose characteristics even before fast-tuning magnetron installation. Beam symmetries and flatnesses were acceptable at all energies and dose rates, and showed no obvious degradation in low dose sub-fields. It is recommended that fast-tuning magnetrons are adopted for accelerators of this design performing step and shoot IMRT. (author)

  7. Comparison of two heterogeneity correction algorithms in pituitary gland treatments with intensity-modulated radiation therapy

    International Nuclear Information System (INIS)

    The dose accuracy calculated by a treatment planning system is directly related to the chosen algorithm. Nowadays, several calculation doses algorithms are commercially available and they differ in calculation time and accuracy, especially when individual tissue densities are taken into account. The aim of this study was to compare two different calculation algorithms from iPlan®, BrainLAB, in the treatment of pituitary gland tumor with intensity-modulated radiation therapy (IMRT). These tumors are located in a region with variable electronic density tissues. The deviations from the plan with no heterogeneity correction were evaluated. To initial validation of the data inserted into the planning system, an IMRT plan was simulated in a anthropomorphic phantom and the dose distribution was measured with a radiochromic film. The gamma analysis was performed in the film, comparing it with dose distributions calculated with X-ray Voxel Monte Carlo (XVMC) algorithm and pencil beam convolution (PBC). Next, 33 patients plans, initially calculated by PBC algorithm, were recalculated with XVMC algorithm. The treatment volumes and organs-at-risk dose-volume histograms were compared. No relevant differences were found in dose-volume histograms between XVMC and PBC. However, differences were obtained when comparing each plan with the plan without heterogeneity correction. (author)

  8. A pencil beam algorithm for intensity modulated proton therapy derived from Monte Carlo simulations.

    Science.gov (United States)

    Soukup, Martin; Fippel, Matthias; Alber, Markus

    2005-11-01

    A pencil beam algorithm as a component of an optimization algorithm for intensity modulated proton therapy (IMPT) is presented. The pencil beam algorithm is tuned to the special accuracy requirements of IMPT, where in heterogeneous geometries both the position and distortion of the Bragg peak and the lateral scatter pose problems which are amplified by the spot weight optimization. Heterogeneity corrections are implemented by a multiple raytracing approach using fluence-weighted sub-spots. In order to derive nuclear interaction corrections, Monte Carlo simulations were performed. The contribution of long ranged products of nuclear interactions is taken into account by a fit to the Monte Carlo results. Energy-dependent stopping power ratios are also implemented. Scatter in optional beam line accessories such as range shifters or ripple filters is taken into account. The collimator can also be included, but without additional scattering. Finally, dose distributions are benchmarked against Monte Carlo simulations, showing 3%/1 mm agreement for simple heterogeneous phantoms. In the case of more complicated phantoms, principal shortcomings of pencil beam algorithms are evident. The influence of these effects on IMPT dose distributions is shown in clinical examples. PMID:16237243

  9. Compact multileaf collimator for conformal and intensity modulated fast neutron therapy: Electromechanical design and validation

    International Nuclear Information System (INIS)

    The electromechanical properties of a 120-leaf, high-resolution, computer-controlled, fast neutron multileaf collimator (MLC) are presented. The MLC replaces an aging, manually operated multirod collimator. The MLC leaves project 5 mm in the isocentric plane perpendicular to the beam axis. A taper is included on the leaves matching beam divergence along one axis. The 5-mm leaf projection width is chosen to give high-resolution conformality across the entire field. The maximum field size provided is 30x30 cm2. To reduce the interleaf transmission a 0.254-mm blocking step is included. End-leaf steps totaling 0.762 mm are also provided allowing opposing leaves to close off within the primary radiation beam. The neutron MLC also includes individual 45 deg. and 60 deg. automated universal tungsten wedges. The automated high-resolution neutron collimation provides an increase in patient throughput capacity, enables a new modality, intensity modulated neutron therapy, and limits occupational radiation exposure by providing remote operation from a shielded console area

  10. Intensity-modulated radiation therapy for malignancies of the nasal cavity and paranasal sinuses

    International Nuclear Information System (INIS)

    Purpose: To report the clinical outcome of patients treated with intensity-modulated radiation therapy (IMRT) for malignancies of the nasal cavity and paranasal sinuses. Methods and Materials: Between 1998 and 2004, 36 patients with malignancies of the sinonasal region were treated with IMRT. Thirty-two patients (89%) were treated in the postoperative setting after gross total resection. Treatment plans were designed to provide a dose of 70 Gy to 95% or more of the gross tumor volume (GTV) and 60 Gy to 95% or more of the clinical tumor volume (CTV) while sparing neighboring critical structures including the optic chiasm, optic nerves, eyes, and brainstem. The primary sites were: 13 ethmoid sinus, 10 maxillary sinus, 7 nasal cavity, and 6 other. Histology was: 12 squamous cell, 7 esthesioneuroblastoma, 5 adenoid cystic, 5 undifferentiated, 5 adenocarcinoma, and 2 other. Median follow-up was 51 months among surviving patients (range, 9-82 months). Results: The 2-year and 5-year estimates of local control were 62% and 58%, respectively. One patient developed isolated distant metastasis, and none developed isolated regional failure. The 5-year rates of disease-free and overall survival were 55% and 45%, respectively. The incidence of ocular toxicity was minimal with no patients reporting decreased vision. Late complications included xerophthalmia (1 patient), lacrimal stenosis (1 patient), and cataract (1 patient). Conclusion: Although IMRT for malignancies of the sinonasal region does not appear to lead to significant improvements in disease control, the low incidence of complications is encouraging

  11. Improved Planning Time and Plan Quality Through Multicriteria Optimization for Intensity-Modulated Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To test whether multicriteria optimization (MCO) can reduce treatment planning time and improve plan quality in intensity-modulated radiotherapy (IMRT). Methods and Materials: Ten IMRT patients (5 with glioblastoma and 5 with locally advanced pancreatic cancers) were logged during the standard treatment planning procedure currently in use at Massachusetts General Hospital (MGH). Planning durations and other relevant planning information were recorded. In parallel, the patients were planned using an MCO planning system, and similar planning time data were collected. The patients were treated with the standard plan, but each MCO plan was also approved by the physicians. Plans were then blindly reviewed 3 weeks after planning by the treating physician. Results: In all cases, the treatment planning time was vastly shorter for the MCO planning (average MCO treatment planning time was 12 min; average standard planning time was 135 min). The physician involvement time in the planning process increased from an average of 4.8 min for the standard process to 8.6 min for the MCO process. In all cases, the MCO plan was blindly identified as the superior plan. Conclusions: This provides the first concrete evidence that MCO-based planning is superior in terms of both planning efficiency and dose distribution quality compared with the current trial and error–based IMRT planning approach.

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

    International Nuclear Information System (INIS)

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

  13. Risk of second malignant neoplasm following proton versus intensity-modulated photon radiotherapies for hepatocellular carcinoma

    Science.gov (United States)

    Taddei, Phillip J.; Howell, Rebecca M.; Krishnan, Sunil; Scarboro, Sarah B.; Mirkovic, Dragan; Newhauser, Wayne D.

    2010-12-01

    Hepatocellular carcinoma (HCC), the sixth most common cancer in the world, is a global health concern. Radiotherapy for HCC is uncommon, largely because of the likelihood of radiation-induced liver disease, an acute side effect that is often fatal. Proton beam therapy (PBT) and intensity-modulated radiation therapy (IMRT) may offer HCC patients a better option for treating the diseased liver tissue while largely sparing the surrounding tissues, especially the non-tumor liver. However, even advanced radiotherapies carry a risk of late effects, including second malignant neoplasms (SMNs). It is unclear whether PBT or IMRT confers less risk of an SMN than the other. The purpose of this study was to compare the predicted risk of developing an SMN for a patient with HCC between PBT and IMRT. For both treatments, radiation doses in organs and tissues from primary radiation were determined using a treatment planning system; doses in organs and tissues from stray radiation from PBT were determined using Monte Carlo simulations and from IMRT using thermo-luminescent dosimeter measurements. Risk models of SMN incidence were taken from the literature. The predicted absolute lifetime attributable risks of SMN incidence were 11.4% after PBT and 19.2% after IMRT. The results of this study suggest that using proton beams instead of photon beams for radiotherapy may reduce the risk of SMN incidence for some HCC patients.

  14. Intensity-modulated radiation therapy to bilateral lower limb extremities concurrently: a planning case study

    Energy Technology Data Exchange (ETDEWEB)

    Fitzgerald, Emma, E-mail: emmafitz1390@gmail.com; Miles, Wesley; Fenton, Paul; Frantzis, Jim [Radiation Oncology, Epworth HealthCare, Victoria (Australia)

    2014-09-15

    Non-melanomatous skin cancers represent 80% of all newly diagnosed cancers in Australia with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) being the most common. A previously healthy 71-year-old woman presented with widespread and tender superficial skin cancers on the lower bilateral limbs. External beam radiation therapy through the use of intensity-modulated radiation therapy (IMRT) was employed as the treatment modality of choice as this technique provides conformal dose distribution to a three-dimensional treatment volume while reducing toxicity to surrounding tissues. The patient was prescribed a dose of 60 Gy to the planning target volume (PTV) with 1.0 cm bolus over the ventral surface of each limb. The beam arrangement consisted of six treatment fields that avoided entry and exit through the contralateral limb. The treatment plans met the International Commission on Radiation Units and Measurements (ICRU) guidelines and produced highly conformal dosimetric results. Skin toxicity was measured against the National Cancer Institute: Common Terminology Criteria for Adverse Events (NCI: CTCAE) version 3. A well-tolerated treatment was delivered with excellent results given the initial extent of the disease. This case study has demonstrated the feasibility and effectiveness of IMRT for skin cancers as an alternative to surgery and traditional superficial radiation therapy, utilising a complex PTV of the extremities for patients with similar presentations.

  15. Strategy for Online Correction of Rotational Organ Motion for Intensity-Modulated Radiotherapy of Prostate Cancer

    International Nuclear Information System (INIS)

    Purpose: To develop and evaluate a correction strategy for prostate rotation using gantry and collimator angle adjustments. Methods and Materials: Gantry and collimator angle adjustments were used to correct for prostate rotation without rotating the table. A formula to partially correct for left-right (LR) rotations was derived through geometric analysis of rotation-induced clinical target volume (CTV) beam's-eye-view shape changes. For 10 prostate patients, intensity-modulated radiotherapy (IMRT) plans with different margins were created. Simulating CTV LR rotation and correcting each beam by a collimator rotation, the corrected CTV dose was compared with the original and uncorrected dose. Effects of residual geometric uncertainties were assessed using a Monte Carlo technique. A large number of treatments representative for prostate patients were simulated. Dose probability histograms of the minimum CTV dose (Dmin) were derived, with and without online correction, resulting in a more realistic margin estimate. Results: Dosimetric analysis of all IMRT plans showed that, with rotational correction and a 2-mm margin, Dmin was constant to within 3% for LR rotations up to ±15o. The Monte Carlo dose probability histograms showed that, with correction, a margin of 4 mm ensured that 90% of patients received a Dmin ≥95% of the prescribed dose. Without correction a margin of 6 mm was required. Conclusions: We developed and tested a practical method for (online) correction of prostate rotation, allowing safe and straightforward implementation of margin reduction and dose escalation

  16. Multibeam tomotherapy: a new treatment unit devised for multileaf collimation, intensity-modulated radiation therapy.

    Science.gov (United States)

    Achterberg, Nils; Müller, Reinhold G

    2007-10-01

    A fully integrated system for treatment planning, application, and verification for automated multileaf collimator (MLC) based, intensity-modulated, image-guided, and adaptive radiation therapy (IMRT, IGRT and ART, respectively) is proposed. Patient comfort, which was the major development goal, will be achieved through a new unit design and short treatment times. Our device for photon beam therapy will consist of a new dual energy linac with five fixed treatment heads positioned evenly along one plane but one electron beam generator only. A minimum of moving parts increases technical reliability and reduces motion times to a minimum. Motion is allowed solely for the MLCs, the robotic patient table, and the small angle gantry rotation of +/- 36 degrees. Besides sophisticated electron beam guidance, this compact setup can be built using existing modules. The flattening-filter-free treatment heads are characterized by reduced beam-on time and contain apertures restricted in one dimension to the area of maximum primary fluence output. In the case of longer targets, this leads to a topographic intensity modulation, thanks to the combination of "step and shoot" MLC delivery and discrete patient couch motion. Owing to the limited number of beam directions, this multislice cone beam serial tomotherapy is referred to as "multibeam tomotherapy." Every patient slice is irradiated by one treatment head at any given moment but for one subfield only. The electron beam is then guided to the next head ready for delivery, while the other heads are preparing their leaves for the next segment. The "Multifocal MLC-positioning" algorithm was programmed to enable treatment planning and optimize treatment time. We developed an overlap strategy for the longitudinally adjacent fields of every beam direction, in doing so minimizing the field match problem and the effects of possible table step errors. Clinical case studies show for the same or better planning target volume coverage, better

  17. Multibeam tomotherapy: A new treatment unit devised for multileaf collimation, intensity-modulated radiation therapy

    International Nuclear Information System (INIS)

    A fully integrated system for treatment planning, application, and verification for automated multileaf collimator (MLC) based, intensity-modulated, image-guided, and adaptive radiation therapy (IMRT, IGRT and ART, respectively) is proposed. Patient comfort, which was the major development goal, will be achieved through a new unit design and short treatment times. Our device for photon beam therapy will consist of a new dual energy linac with five fixed treatment heads positioned evenly along one plane but one electron beam generator only. A minimum of moving parts increases technical reliability and reduces motion times to a minimum. Motion is allowed solely for the MLCs, the robotic patient table, and the small angle gantry rotation of ±36 deg. . Besides sophisticated electron beam guidance, this compact setup can be built using existing modules. The flattening-filter-free treatment heads are characterized by reduced beam-on time and contain apertures restricted in one dimension to the area of maximum primary fluence output. In the case of longer targets, this leads to a topographic intensity modulation, thanks to the combination of ''step and shoot'' MLC delivery and discrete patient couch motion. Owing to the limited number of beam directions, this multislice cone beam serial tomotherapy is referred to as ''multibeam tomotherapy.'' Every patient slice is irradiated by one treatment head at any given moment but for one subfield only. The electron beam is then guided to the next head ready for delivery, while the other heads are preparing their leaves for the next segment. The ''Multifocal MLC-positioning'' algorithm was programmed to enable treatment planning and optimize treatment time. We developed an overlap strategy for the longitudinally adjacent fields of every beam direction, in doing so minimizing the field match problem and the effects of possible table step errors. Clinical case studies show for the same or better planning target volume coverage

  18. Non-Fragile H∞Control for Random Pulse Width Modulation of DCM Boost Converter%DCM Boost变换器随机PWM非脆弱H∞控制

    Institute of Scientific and Technical Information of China (English)

    冉华军; 李翔; 肖鹏

    2014-01-01

    引入两模态马尔科夫链随机PWM策略到DCM Boost变换器,推导建立了变换器的离散随机跳变模型,并基于随机跳变系统非脆弱H∞控制理论为Boost变换器设计了非脆弱H∞控制器,利用Simulink软件平台设计仿真电路进行验证。仿真分析表明,设计的控制器改善了Boost变换器的EMI品质,对控制器参数摄动表现出非脆弱性,使整个变换器系统具有较好的鲁棒性。%The two-state-Markov-chain random pulse width modulation (PWM) scheme was introduced into the DCM Boost converter. This paper derived the random discrete-time jumping model of the converter and designed the non-fragile H∞ con-troller based on non-fragile H∞ control theory of stochastic jumping system. The simulation was done to check the validity of non-fragile H∞controller on the Simulink platform. The simulation analysis indicates that the designed controller has improved the EMI quality of Boost converter along with non-fragility to its parameters uncertainty, and with better robust for the whole converter system.

  19. Comparison of plan optimization for single and dual volumetric-modulated arc therapy versus intensity-modulated radiation therapy during post-mastectomy regional irradiation

    OpenAIRE

    Zhao, Li-Rong; ZHOU, YI-BING; Sun, Jian-Guo

    2016-01-01

    The aim of the present study was to investigate volumetric-modulated arc therapy (VMAT) with single arc (1ARC) and dual arc (2ARC), and intensity-modulated radiation therapy (IMRT), and to evaluate the quality and delivery efficiency of post-mastectomy regional irradiation. A total of 24 female patients who required post-mastectomy regional irradiation were enrolled into the current study, and 1ARC, 2ARC and IMRT plans were designed for each individual patient. The quality of these plans was ...

  20. Intensity-Modulated Proton Therapy Further Reduces Normal Tissue Exposure During Definitive Therapy for Locally Advanced Distal Esophageal Tumors: A Dosimetric Study

    Energy Technology Data Exchange (ETDEWEB)

    Welsh, James, E-mail: jwelsh@mdanderson.org [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Gomez, Daniel; Palmer, Matthew B.; Riley, Beverly A.; Mayankkumar, Amin V.; Komaki, Ritsuko [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Dong, Lei; Zhu, X. Ronald [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Likhacheva, Anna; Liao, Zhongxing [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Hofstetter, Wayne L. [Department of Thoracic and Cardiovascular Surgery, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Ajani, Jaffer A. [Department of Gastrointestinal Medical Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Cox, James D. [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)

    2011-12-01

    Purpose: We have previously found that {<=} 75% of treatment failures after chemoradiotherapy for unresectable esophageal cancer appear within the gross tumor volume and that intensity-modulated (photon) radiotherapy (IMRT) might allow dose escalation to the tumor without increasing normal tissue toxicity. Proton therapy might allow additional dose escalation, with even lower normal tissue toxicity. In the present study, we compared the dosimetric parameters for photon IMRT with that for intensity-modulated proton therapy (IMPT) for unresectable, locally advanced, distal esophageal cancer. Patients and Methods: Four plans were created for each of 10 patients. IMPT was delivered using anteroposterior (AP)/posteroanterior beams, left posterior oblique/right posterior oblique (LPO/RPO) beams, or AP/LPO/RPO beams. IMRT was delivered with a concomitant boost to the gross tumor volume. The dose was 65.8 Gy to the gross tumor volume and 50.4 Gy to the planning target volume in 28 fractions. Results: Relative to IMRT, the IMPT (AP/posteroanterior) plan led to considerable reductions in the mean lung dose (3.18 vs. 8.27 Gy, p < .0001) and the percentage of lung volume receiving 5, 10, and 20 Gy (p {<=} .0006) but did not reduce the cardiac dose. The IMPT LPO/RPO plan also reduced the mean lung dose (4.9 Gy vs. 8.2 Gy, p < .001), the heart dose (mean cardiac dose and percentage of the cardiac volume receiving 10, 20, and 30 Gy, p {<=} .02), and the liver dose (mean hepatic dose 5 Gy vs. 14.9 Gy, p < .0001). The IMPT AP/LPO/RPO plan led to considerable reductions in the dose to the lung (p {<=} .005), heart (p {<=} .003), and liver (p {<=} .04). Conclusions: Compared with IMRT, IMPT for distal esophageal cancer lowered the dose to the heart, lung, and liver. The AP/LPO/RPO beam arrangement was optimal for sparing all three organs. The dosimetric benefits of protons will need to be tailored to each patient according to their specific cardiac and pulmonary risks. IMPT for

  1. Hemithoracic Intensity Modulated Radiation Therapy After Pleurectomy/Decortication for Malignant Pleural Mesothelioma: Toxicity, Patterns of Failure, and a Matched Survival Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chance, William W. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Rice, David C. [Department of Thoracic and Cardiovascular Surgery, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Allen, Pamela K. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Tsao, Anne S. [Department of Thoracic/Head and Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Fontanilla, Hiral P. [Princeton Radiation Oncology, Monroe Township, New Jersey (United States); Liao, Zhongxing; Chang, Joe Y.; Tang, Chad; Pan, Hubert Y.; Welsh, James W. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Mehran, Reza J. [Department of Thoracic and Cardiovascular Surgery, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Gomez, Daniel R., E-mail: dgomez@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

    2015-01-01

    Purpose: To investigate safety, efficacy, and recurrence after hemithoracic intensity modulated radiation therapy after pleurectomy/decortication (PD-IMRT) and after extrapleural pneumonectomy (EPP-IMRT). Methods and Materials: In 2009-2013, 24 patients with mesothelioma underwent PD-IMRT to the involved hemithorax to a dose of 45 Gy, with an optional integrated boost; 22 also received chemotherapy. Toxicity was scored with the Common Terminology Criteria for Adverse Events v4.0. Pulmonary function was compared at baseline, after surgery, and after IMRT. Kaplan-Meier analysis was used to calculate overall survival (OS), progression-free survival (PFS), time to locoregional failure, and time to distant metastasis. Failures were in-field, marginal, or out of field. Outcomes were compared with those of 24 patients, matched for age, nodal status, performance status, and chemotherapy, who had received EPP-IMRT. Results: Median follow-up time was 12.2 months. Grade 3 toxicity rates were 8% skin and 8% pulmonary. Pulmonary function declined from baseline to after surgery (by 21% for forced vital capacity, 16% for forced expiratory volume in 1 second, and 19% for lung diffusion of carbon monoxide [P for all = .01]) and declined still further after IMRT (by 31% for forced vital capacity [P=.02], 25% for forced expiratory volume in 1 second [P=.01], and 30% for lung diffusion of carbon monoxide [P=.01]). The OS and PFS rates were 76% and 67%, respectively, at 1 year and 56% and 34% at 2 years. Median OS (28.4 vs 14.2 months, P=.04) and median PFS (16.4 vs 8.2 months, P=.01) favored PD-IMRT versus EPP-IMRT. No differences were found in grade 4-5 toxicity (0 of 24 vs 3 of 24, P=.23), median time to locoregional failure (18.7 months vs not reached, P not calculable), or median time to distant metastasis (18.8 vs 11.8 months, P=.12). Conclusions: Hemithoracic intensity modulated radiation therapy after pleurectomy/decortication produced little high-grade toxicity but

  2. Verification of intensity modulated radiation therapy beams using a tissue equivalent plastic scintillator dosimetry system

    Science.gov (United States)

    Petric, Martin Peter

    This thesis describes the development and implementation of a novel method for the dosimetric verification of intensity modulated radiation therapy (IMRT) fields with several advantages over current techniques. Through the use of a tissue equivalent plastic scintillator sheet viewed by a charge-coupled device (CCD) camera, this method provides a truly tissue equivalent dosimetry system capable of efficiently and accurately performing field-by-field verification of IMRT plans. This work was motivated by an initial study comparing two IMRT treatment planning systems. The clinical functionality of BrainLAB's BrainSCAN and Varian's Helios IMRT treatment planning systems were compared in terms of implementation and commissioning, dose optimization, and plan assessment. Implementation and commissioning revealed differences in the beam data required to characterize the beam prior to use with the BrainSCAN system requiring higher resolution data compared to Helios. This difference was found to impact on the ability of the systems to accurately calculate dose for highly modulated fields, with BrainSCAN being more successful than Helios. The dose optimization and plan assessment comparisons revealed that while both systems use considerably different optimization algorithms and user-control interfaces, they are both capable of producing substantially equivalent dose plans. The extensive use of dosimetric verification techniques in the IMRT treatment planning comparison study motivated the development and implementation of a novel IMRT dosimetric verification system. The system consists of a water-filled phantom with a tissue equivalent plastic scintillator sheet built into the top surface. Scintillation light is reflected by a plastic mirror within the phantom towards a viewing window where it is captured using a CCD camera. Optical photon spread is removed using a micro-louvre optical collimator and by deconvolving a glare kernel from the raw images. Characterization of this

  3. Dosimetric comparison of hybrid volumetric-modulated arc therapy, volumetric-modulated arc therapy, and intensity-modulated radiation therapy for left-sided early breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jia-Fu [Department of Radiation Physics, Taichung Veterans General Hospital, Taichung, Taiwan (China); Yeh, Dah-Cherng [Department of General Surgery, Taichung Veterans General Hospital, Taichung, Taiwan (China); Yeh, Hui-Ling, E-mail: hlyeh@vghtc.gov.tw [Department of Radiation Oncology, Taichung Veterans General Hospital, Taichung, Taiwan (China); Chang, Chen-Fa [Department of Radiation Physics, Taichung Veterans General Hospital, Taichung, Taiwan (China); Lin, Jin-Ching [Department of Radiation Oncology, Taichung Veterans General Hospital, Taichung, Taiwan (China)

    2015-10-01

    To compare the dosimetric performance of 3 different treatment techniques: hybrid volumetric-modulated arc therapy (hybrid-VMAT), pure-VMAT, and fixed-field intensity-modulated radiation therapy (F-IMRT) for whole-breast irradiation of left-sided early breast cancer. The hybrid-VMAT treatment technique and 2 other treatment techniques—pure-VMAT and F-IMRT—were compared retrospectively in 10 patients with left-sided early breast cancer. The treatment plans of these patients were replanned using the same contours based on the original computed tomography (CT) data sets. Dosimetric parameters were calculated to evaluate plan quality. Total monitor units (MUs) and delivery time were also recorded and evaluated. The hybrid-VMAT plan generated the best results in dose coverage of the target and the dose uniformity inside the target (p < 0.0001 for conformal index [CI]; p = 0.0002 for homogeneity index [HI] of planning target volume [PTV]{sub 50.4} {sub Gy} and p < 0.0001 for HI of PTV{sub 62} {sub Gy}). Volumes of ipsilateral lung irradiated to doses of 20 Gy (V{sub 20} {sub Gy}) and 5 Gy (V{sub 5} {sub Gy}) by the hybrid-VMAT plan were significantly less than those of the F-IMRT and the pure-VMAT plans. The volume of ipsilateral lung irradiated to a dose of 5 Gy was significantly less using the hybrid-VMAT plan than that using the F-IMRT or the pure-VMAT plan. The total mean MUs for the hybrid-VMAT plan were significantly less than those for the F-IMRT or the pure-VMAT plan. The mean machine delivery time was 3.23 ± 0.29 minutes for the hybrid-VMAT plans, which is longer than that for the pure-VMAT plans but shorter than that for the F-IMRT plans. The hybrid-VMAT plan is feasible for whole-breast irradiation of left-sided early breast cancer.

  4. Dosimetric comparison of hybrid volumetric-modulated arc therapy, volumetric-modulated arc therapy, and intensity-modulated radiation therapy for left-sided early breast cancer

    International Nuclear Information System (INIS)

    To compare the dosimetric performance of 3 different treatment techniques: hybrid volumetric-modulated arc therapy (hybrid-VMAT), pure-VMAT, and fixed-field intensity-modulated radiation therapy (F-IMRT) for whole-breast irradiation of left-sided early breast cancer. The hybrid-VMAT treatment technique and 2 other treatment techniques—pure-VMAT and F-IMRT—were compared retrospectively in 10 patients with left-sided early breast cancer. The treatment plans of these patients were replanned using the same contours based on the original computed tomography (CT) data sets. Dosimetric parameters were calculated to evaluate plan quality. Total monitor units (MUs) and delivery time were also recorded and evaluated. The hybrid-VMAT plan generated the best results in dose coverage of the target and the dose uniformity inside the target (p < 0.0001 for conformal index [CI]; p = 0.0002 for homogeneity index [HI] of planning target volume [PTV]50.4 Gy and p < 0.0001 for HI of PTV62 Gy). Volumes of ipsilateral lung irradiated to doses of 20 Gy (V20 Gy) and 5 Gy (V5 Gy) by the hybrid-VMAT plan were significantly less than those of the F-IMRT and the pure-VMAT plans. The volume of ipsilateral lung irradiated to a dose of 5 Gy was significantly less using the hybrid-VMAT plan than that using the F-IMRT or the pure-VMAT plan. The total mean MUs for the hybrid-VMAT plan were significantly less than those for the F-IMRT or the pure-VMAT plan. The mean machine delivery time was 3.23 ± 0.29 minutes for the hybrid-VMAT plans, which is longer than that for the pure-VMAT plans but shorter than that for the F-IMRT plans. The hybrid-VMAT plan is feasible for whole-breast irradiation of left-sided early breast cancer

  5. Learning Boost C++ libraries

    CERN Document Server

    Mukherjee, Arindam

    2015-01-01

    If you are a C++ programmer who has never used Boost libraries before, this book will get you up-to-speed with using them. Whether you are developing new C++ software or maintaining existing code written using Boost libraries, this hands-on introduction will help you decide on the right library and techniques to solve your practical programming problems.

  6. Dose escalation for maxillary sinus cancer using intensity-modulated radiation therapy (IMRT)

    International Nuclear Information System (INIS)

    Purpose: To determine the feasibility of dose escalation in radiotherapy for maxillary sinus cancer using intensity-modulated radiation therapy, and to compare the resulting dose distribution, dose-volume histogram, and TCP/NTCP data to those obtained with standard 3D conformal radiotherapy (3D-CRT) at our institution. Methods and Materials: Five cases of locally advanced or unresectable maxillary sinus cancer were selected for analysis. All patients had previously been treated with 3D conformal radiotherapy at our institution. With 3D-CRT, the prescription dose to the PTV was generally limited by the tolerance of the optic chiasm to approximately 54 Gy or slightly higher. The contralateral eye was always spared, while the ipsilateral eye was usually sacrificed. These cases were then replanned with an inverse planning algorithm developed at our institution which employs an iterative conjugate gradient search method to generate optimized intensity-modulated beams. Beam fluences were simulated using a multileaf collimator (MLC) with a 1.0 cm leaf width, or a mini-multileaf collimator (mini-MLC) with a 0.5 cm leaf width. Maximal dose escalation was attempted, again with the optic chiasm tolerance as the dose-limiting constraint. Attempts were made to spare the ipsilateral eye as well, where doing so did not preclude adequate coverage of the PTV. Dose distribution and dose-volume histogram data resulting from these attempts were then compared to those from 3D-CRT plans. TCPs and NTCPs were calculated based upon available data and compared. The effect of using a mini-MLC versus a standard MLC was also compared. Results: In all five cases, dose escalation of 5 to 10 Gy above the prescription doses allowed by 3D-CRT plans was achieved. IMRT allowed for tighter conformation of isodose lines around the PTV and away from critical normal tissues, thereby permitting this dose escalation. The improved conformality of dose distributions was further demonstrated by the following

  7. A more robust boosting algorithm

    OpenAIRE

    Freund, Yoav

    2009-01-01

    We present a new boosting algorithm, motivated by the large margins theory for boosting. We give experimental evidence that the new algorithm is significantly more robust against label noise than existing boosting algorithm.

  8. Adoption of Intensity Modulated Radiation Therapy For Early-Stage Breast Cancer From 2004 Through 2011

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Elyn H. [Yale School of Medicine, New Haven, Connecticut (United States); Mougalian, Sarah S. [Yale School of Medicine, New Haven, Connecticut (United States); Yale Cancer Center, New Haven, Connecticut (United States); Cancer Outcomes, Public Policy, and Effectiveness Research Center at Yale, New Haven, Connecticut (United States); Soulos, Pamela R. [Yale School of Medicine, New Haven, Connecticut (United States); Cancer Outcomes, Public Policy, and Effectiveness Research Center at Yale, New Haven, Connecticut (United States); Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut (United States); Smith, Benjamin D. [Department of Radiation Oncology, MD Anderson Cancer Center, Houston, Texas (United States); Haffty, Bruce G. [Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey (United States); Gross, Cary P. [Yale School of Medicine, New Haven, Connecticut (United States); Cancer Outcomes, Public Policy, and Effectiveness Research Center at Yale, New Haven, Connecticut (United States); Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut (United States); Yu, James B., E-mail: james.b.yu@yale.edu [Yale School of Medicine, New Haven, Connecticut (United States); Cancer Outcomes, Public Policy, and Effectiveness Research Center at Yale, New Haven, Connecticut (United States); Department of Therapeutic Radiology, Yale School of Medicine, New Haven, Connecticut (United States)

    2015-02-01

    Purpose: Intensity modulated radiation therapy (IMRT) is a newer method of radiation therapy (RT) that has been increasingly adopted as an adjuvant treatment after breast-conserving surgery (BCS). IMRT may result in improved cosmesis compared to standard RT, although at greater expense. To investigate the adoption of IMRT, we examined trends and factors associated with IMRT in women under the age of 65 with early stage breast cancer. Methods and Materials: We performed a retrospective study of early stage breast cancer patients treated with BCS followed by whole-breast irradiation (WBI) who were ≤65 years old in the National Cancer Data Base from 2004 to 2011. We used logistic regression to identify factors associated with receipt of IMRT (vs standard RT). Results: We identified 11,089 women with early breast cancer (9.6%) who were treated with IMRT and 104,448 (90.4%) who were treated with standard RT, after BCS. The proportion of WBI patients receiving IMRT increased yearly from 2004 to 2009, with 5.3% of WBI patients receiving IMRT in 2004 and 11.6% receiving IMRT in 2009. Further use of IMRT declined afterward, with the proportion remaining steady at 11.0% and 10.7% in 2010 and 2011, respectively. Patients treated in nonacademic community centers were more likely to receive IMRT (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.30-1.43 for nonacademic vs academic center). Compared to privately insured patients, the uninsured patients (OR, 0.81; 95% CI, 0.70-0.95) and those with Medicaid insurance (OR, 0.87; 95% CI, 0.79-0.95) were less likely to receive IMRT. Conclusions: The use of IMRT rose from 2004 to 2009 and then stabilized. Important nonclinical factors associated with IMRT use included facility type and insurance status.

  9. Optimized point dose measurement: An effective tool for QA in intensity-modulated radiotherapy

    Directory of Open Access Journals (Sweden)

    Kumar Alok

    2007-01-01

    Full Text Available In some cases of Intensity-modulated radiotherapy (IMRT point dose measurement, there exists significant deviation between calculated and measured dose at isocenter, sometimes greater than ±3%. This may be because IMRT fields generate complex profiles at the reference point. The deviation arises due to lack of lateral electronic equilibrium for small fields, and other factors such as leakage and scatter contribution. Measurements were done using 0.125-cc ion chamber and Universal IMRT phantom (both from PTW-Freiburg. The aim is to find a suitable point of measurement for the chamber to avoid discrepancy between calculated and measured dose. Various beam profiles were generated in the plane of the chamber for each field by implementing patient plan on the IMRT phantom. The profiles show that for the fields which are showing deviation, the ion chamber lies in the steep-gradient region. To rectify the problem, the TPS (Treatment Planning System calculated dose is found out at various points in the measurement plane of the chamber at isocenter. The necessary displacement to the chamber, as noted from the TPS, was given to obtain the optimum result. Twenty cases were studied for optimization, whose percentage deviation was more than ±3%. The results were well within tolerance criteria of ±3% after optimization. The mean percentage deviation value for the 20 cases studied, with standard deviation of 2.33 under 95% confidence interval, was found out to be 2.10% ± 1.14. Those cases that have significant variation even after optimization are further studied with film dosimetry.

  10. Adoption of Intensity Modulated Radiation Therapy For Early-Stage Breast Cancer From 2004 Through 2011

    International Nuclear Information System (INIS)

    Purpose: Intensity modulated radiation therapy (IMRT) is a newer method of radiation therapy (RT) that has been increasingly adopted as an adjuvant treatment after breast-conserving surgery (BCS). IMRT may result in improved cosmesis compared to standard RT, although at greater expense. To investigate the adoption of IMRT, we examined trends and factors associated with IMRT in women under the age of 65 with early stage breast cancer. Methods and Materials: We performed a retrospective study of early stage breast cancer patients treated with BCS followed by whole-breast irradiation (WBI) who were ≤65 years old in the National Cancer Data Base from 2004 to 2011. We used logistic regression to identify factors associated with receipt of IMRT (vs standard RT). Results: We identified 11,089 women with early breast cancer (9.6%) who were treated with IMRT and 104,448 (90.4%) who were treated with standard RT, after BCS. The proportion of WBI patients receiving IMRT increased yearly from 2004 to 2009, with 5.3% of WBI patients receiving IMRT in 2004 and 11.6% receiving IMRT in 2009. Further use of IMRT declined afterward, with the proportion remaining steady at 11.0% and 10.7% in 2010 and 2011, respectively. Patients treated in nonacademic community centers were more likely to receive IMRT (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.30-1.43 for nonacademic vs academic center). Compared to privately insured patients, the uninsured patients (OR, 0.81; 95% CI, 0.70-0.95) and those with Medicaid insurance (OR, 0.87; 95% CI, 0.79-0.95) were less likely to receive IMRT. Conclusions: The use of IMRT rose from 2004 to 2009 and then stabilized. Important nonclinical factors associated with IMRT use included facility type and insurance status

  11. Phase II Trial of Hypofractionated Image-Guided Intensity-Modulated Radiotherapy for Localized Prostate Adenocarcinoma

    International Nuclear Information System (INIS)

    Purpose: To assess in a prospective trial the feasibility and late toxicity of hypofractionated radiotherapy (RT) for prostate cancer. Methods and Materials: Eligible patients had clinical stage T1c-2cNXM0 disease. They received 60 Gy in 20 fractions over 4 weeks with intensity-modulated radiotherapy including daily on-line image guidance with intraprostatic fiducial markers. Results: Between June 2001 and March 2004, 92 patients were treated with hypofractionated RT. The cohort had a median prostate-specific antigen value of 7.06 ng/mL. The majority had Gleason grade 5-6 (38%) or 7 (59%) disease, and 82 patients had T1c-T2a clinical staging. Overall, 29 patients had low-risk, 56 intermediate-risk, and 7 high-risk disease. Severe acute toxicity (Grade 3-4) was rare, occurring in only 1 patient. Median follow-up was 38 months. According to the Phoenix definition for biochemical failure, the rate of biochemical control at 14 months was 97%. According to the previous American Society for Therapeutic Radiology and Oncology definition, biochemical control at 3 years was 76%. The incidence of late toxicity was low, with no severe (Grade ≥3) toxicity at the most recent assessment. Conclusions: Hypofractionated RT using 60 Gy in 20 fractions over 4 weeks with image guidance is feasible and is associated with low rates of late bladder and rectal toxicity. At early follow-up, biochemical outcome is comparable to that reported for conventionally fractionated controls. The findings are being tested in an ongoing, multicenter, Phase III trial

  12. Intensity modulated whole pelvic radiotherapy in patients with cervix cancer: analysis of acute toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young Min; Lee, Hyung Sik; Hur, Won Joo; Cha, Moon Seok; Kim, Hyun Ho [School of Medicine, Dong-A University, Busan (Korea, Republic of)

    2006-12-15

    To evaluate acute toxicities in cervix cancer patients receiving intensity modulated whole pelvic radiation therapy (IM-WPRT). Between August 2004 and April 2006, 17 patients who underwent IM-WPRT were analysed. An intravenous contrast agent was used for radiotherapy planning computed tomography (CT). The central clinical target volume (CTV) included the primary tumor, uterus, vagina, and parametrium. The nodal CTV was defined as the lymph nodes larger than 1 cm seen on CT and the contrased-enhanced pelvic vessels. The planning target volume (PTV) was the 1-cm expanded volume around the central CTV, except for a 5-mm expansion from the posterior vagina, and the nodal PTV was defined as the nodal CTV plus a 1.5 cm margin. IM-WPRT was prescribed to deliver a dose of 50 Gy to more than 95% of the PTV. Acute toxicity was assessed with common toxicity criteria up to 60 days after radiotherapy. Grade 1 nausea developed in 10 (58.9%) patients, and grade 1 and 2 diarrhea developed in 11 (64.7%) and 1 (5.9%) patients, respectively. No grade 3 or higher gastrointestinal toxicity was seen. Leukopenia, anemia, and thrombocytopenia occurred in 15 (88.2%). 7 (41.2%), and 2 (11.8%) patients, respectively, as hematologic toxicities. Grade 3 leukopenia developed in 2 patients who were treated with concurrent chemoradiotherapy. IM-WPRT can be a useful treatment for cervix cancer patients with decreased severe acute toxicities and a resultant improved compliance to whole pelvic irradiation.

  13. Intensity modulated radiation-therapy for preoperative posterior abdominal wall irradiation of retroperitoneal liposarcomas

    International Nuclear Information System (INIS)

    Purpose: Preoperative external-beam radiation therapy (preop RT) in the management of Retroperitoneal Liposarcomas (RPLS) typically involves the delivery of radiation to the entire tumor mass: yet this may not be necessary. The purpose of this study is to evaluate a new strategy of preop RT for RPLS in which the target volume is limited to the contact area between the tumoral mass and the posterior abdominal wall. Methods and Materials: Between June 2000 and Jan 2005, 18 patients with the diagnosis of RPLS have been treated following a pilot protocol of pre-op RT, 50 Gy in 25 fractions of 2 Gy/day. The Clinical Target Volume (CTV) has been limited to the posterior abdominal wall, region at higher risk for local relapse. A Three-Dimensional conformal (3D-CRT) and an Intensity Modulated (IMRT) plan were generated and compared; toxicity was reported following the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events v3.0. Results: All patients completed the planned treatment and the acute toxicity was tolerable: 2 patients experienced Grade 3 and 1 Grade 2 anorexia while 2 patients developed Grade 2 nausea. IMRT allows a better sparing of the ipsilateral and the contralateral kidney. All tumors were successfully resected without major complications. At a median follow-up of 27 months 2 patients developed a local relapse and 1 lung metastasis. Conclusions: Our strategy of preop RT is feasible and well tolerated: the rate of resectability is not compromised by limiting the preop CTV to the posterior abdominal wall and a better critical-structures sparing is obtained with IMRT

  14. Intensity-Modulated Radiation Therapy With Concurrent Chemotherapy as Preoperative Treatment for Localized Gastric Adenocarcinoma

    International Nuclear Information System (INIS)

    Purpose: The goal of this study was to evaluate dosimetric parameters, acute toxicity, pathologic response, and local control in patients treated with preoperative intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy for localized gastric adenocarcinoma. Methods: Between November 2007 and April 2010, 25 patients with localized gastric adenocarcinoma were treated with induction chemotherapy, followed by preoperative IMRT and concurrent chemotherapy and, finally, surgical resection. The median radiation therapy dose was 45 Gy. Concurrent chemotherapy was 5-fluorouracil and oxaliplatin in 18 patients, capecitabine in 3, and other regimens in 4. Subsequently, resection was performed with total gastrectomy in 13 patients, subtotal gastrectomy in 7, and other surgeries in 5. Results: Target coverage, expressed as the ratio of the minimum dose received by 99% of the planning target volume to the prescribed dose, was a median of 0.97 (range, 0.92–1.01). The median V30 (percentage of volume receiving at least 30 Gy) for the liver was 26%; the median V20 (percentage of volume receiving at least 20 Gy) for the right and left kidneys was 14% and 24%, respectively; and the median V40 (percentage of volume receiving at least 40 Gy) for the heart was 18%. Grade 3 acute toxicity developed in 14 patients (56%), including dehydration in 10, nausea in 8, and anorexia in 5. Grade 4 acute toxicity did not develop in any patient. There were no significant differences in the rates of acute toxicity, hospitalization, or feeding tube use in comparison to those in a group of 50 patients treated with preoperative three-dimensional conformal radiation therapy with concurrent chemotherapy. R0 resection was obtained in 20 patients (80%), and pathologic complete response occurred in 5 (20%). Conclusions: Preoperative IMRT for gastric adenocarcinoma was well tolerated, accomplished excellent target coverage and normal structure sparing, and led to appropriate pathologic

  15. Automation and Intensity Modulated Radiation Therapy for Individualized High-Quality Tangent Breast Treatment Plans

    International Nuclear Information System (INIS)

    Purpose: To demonstrate the large-scale clinical implementation and performance of an automated treatment planning methodology for tangential breast intensity modulated radiation therapy (IMRT). Methods and Materials: Automated planning was used to prospectively plan tangential breast IMRT treatment for 1661 patients between June 2009 and November 2012. The automated planning method emulates the manual steps performed by the user during treatment planning, including anatomical segmentation, beam placement, optimization, dose calculation, and plan documentation. The user specifies clinical requirements of the plan to be generated through a user interface embedded in the planning system. The automated method uses heuristic algorithms to define and simplify the technical aspects of the treatment planning process. Results: Automated planning was used in 1661 of 1708 patients receiving tangential breast IMRT during the time interval studied. Therefore, automated planning was applicable in greater than 97% of cases. The time for treatment planning using the automated process is routinely 5 to 6 minutes on standard commercially available planning hardware. We have shown a consistent reduction in plan rejections from plan reviews through the standard quality control process or weekly quality review multidisciplinary breast rounds as we have automated the planning process for tangential breast IMRT. Clinical plan acceptance increased from 97.3% using our previous semiautomated inverse method to 98.9% using the fully automated method. Conclusions: Automation has become the routine standard method for treatment planning of tangential breast IMRT at our institution and is clinically feasible on a large scale. The method has wide clinical applicability and can add tremendous efficiency, standardization, and quality to the current treatment planning process. The use of automated methods can allow centers to more rapidly adopt IMRT and enhance access to the documented

  16. Expert Consensus Contouring Guidelines for Intensity Modulated Radiation Therapy in Esophageal and Gastroesophageal Junction Cancer

    International Nuclear Information System (INIS)

    Purpose/Objective(s): Current guidelines for esophageal cancer contouring are derived from traditional 2-dimensional fields based on bony landmarks, and they do not provide sufficient anatomic detail to ensure consistent contouring for more conformal radiation therapy techniques such as intensity modulated radiation therapy (IMRT). Therefore, we convened an expert panel with the specific aim to derive contouring guidelines and generate an atlas for the clinical target volume (CTV) in esophageal or gastroesophageal junction (GEJ) cancer. Methods and Materials: Eight expert academically based gastrointestinal radiation oncologists participated. Three sample cases were chosen: a GEJ cancer, a distal esophageal cancer, and a mid-upper esophageal cancer. Uniform computed tomographic (CT) simulation datasets and accompanying diagnostic positron emission tomographic/CT images were distributed to each expert, and the expert was instructed to generate gross tumor volume (GTV) and CTV contours for each case. All contours were aggregated and subjected to quantitative analysis to assess the degree of concordance between experts and to generate draft consensus contours. The panel then refined these contours to generate the contouring atlas. Results: The κ statistics indicated substantial agreement between panelists for each of the 3 test cases. A consensus CTV atlas was generated for the 3 test cases, each representing common anatomic presentations of esophageal cancer. The panel agreed on guidelines and principles to facilitate the generalizability of the atlas to individual cases. Conclusions: This expert panel successfully reached agreement on contouring guidelines for esophageal and GEJ IMRT and generated a reference CTV atlas. This atlas will serve as a reference for IMRT contours for clinical practice and prospective trial design. Subsequent patterns of failure analyses of clinical datasets using these guidelines may require modification in the future

  17. Changes Mimicking New Leptomeningeal Disease After Intensity-Modulated Radiotherapy for Medulloblastoma

    International Nuclear Information System (INIS)

    Purpose: Acute and late changes in magnetic resonance imaging of the pediatric brain have been described after radiotherapy (RT). We report the post-RT neuroimaging changes in the posterior fossa after intensity-modulated RT (IMRT) in children with medulloblastoma and contrast them with those of leptomeningeal disease. Methods and Materials: We performed a retrospective review of 53 consecutive children with medulloblastoma who were treated with craniospinal RT followed by IMRT to the posterior fossa and chemotherapy between 1997 and 2006. Results: After IMRT to the posterior fossa, 8 (15%) of 53 patients developed increased fluid-attenuated inversion-recovery signal changes in the brainstem or cerebellum and patchy, multifocal, nodular contrast enhancement at a median of 6 months. The enhancement superficially resembled leptomeningeal disease. However, the enhancement resolved without intervention at a median of 6 months later. The accompanying fluid-attenuated inversion-recovery signal changes occasionally preceded the enhancement, were often parenchymal in location, and resolved or persisted to a lesser degree. All 8 patients with transient magnetic resonance imaging changes in the posterior fossa were alive at last follow-up. In contrast, leptomeningeal disease occurred in 8 (15%) of our 53 patients at a median of 19.5 months after IMRT completion. Of these 8 patients, 7 demonstrated initial nodular enhancement outside the conformal field, and 7 patients died. Conclusion: Magnetic resonance imaging changes can occur in the posterior fossa of children treated with IMRT for medulloblastoma. In our experience, these transient changes occur at a characteristic time and location after RT, allowing them to be distinguished from leptomeningeal disease

  18. Comparison of coplanar and noncoplanar intensity-modulated radiation therapy and helical tomotherapy for hepatocellular carcinoma

    International Nuclear Information System (INIS)

    To compare the differences in dose-volume data among coplanar intensity modulated radiotherapy (IMRT), noncoplanar IMRT, and helical tomotherapy (HT) among patients with hepatocellular carcinoma (HCC) and portal vein thrombosis (PVT). Nine patients with unresectable HCC and PVT underwent step and shoot coplanar IMRT with intent to deliver 46 - 54 Gy to the tumor and portal vein. The volume of liver received 30Gy was set to keep less than 30% of whole normal liver (V30 < 30%). The mean dose to at least one side of kidney was kept below 23 Gy, and 50 Gy as for stomach. The maximum dose was kept below 47 Gy for spinal cord. Several parameters including mean hepatic dose, percent volume of normal liver with radiation dose at X Gy (Vx), uniformity index, conformal index, and doses to organs at risk were evaluated from the dose-volume histogram. HT provided better uniformity for the planning-target volume dose coverage than both IMRT techniques. The noncoplanar IMRT technique reduces the V10 to normal liver with a statistically significant level as compared to HT. The constraints for the liver in the V30 for coplanar IMRT vs. noncoplanar IMRT vs. HT could be reconsidered as 21% vs. 17% vs. 17%, respectively. When delivering 50 Gy and 60-66 Gy to the tumor bed, the constraints of mean dose to the normal liver could be less than 20 Gy and 25 Gy, respectively. Noncoplanar IMRT and HT are potential techniques of radiation therapy for HCC patients with PVT. Constraints for the liver in IMRT and HT could be stricter than for 3DCRT

  19. Gel-layer dosimetry for dose verification in intensity-modulated radiation therapy

    Science.gov (United States)

    Tomatis, S.; Carrara, M.; Gambarini, G.; Marchesini, R.; Valente, M.

    2007-09-01

    Intensity-modulated radiotherapy (IMRT) is a technique in which the radiation fluence within each of the treatment beams is not uniformly distributed. This allows the patient dose to follow the boundaries even of a target volume of complex shape, and, virtually, to spare critical healthy organs at risk. The agreement between planned and delivered IMRT dose is verified by means of standard dosimetric methods such as film dosimetry or semiconductors array dosimetry. In this paper, we compare the output of a commercial device using an array of diodes for IMRT absolute dose verification with the output of a gel dosimeter, composed by a 10×8 cm 2 rectangular layer of a tissue-equivalent gel matrix in which a proper chemical dosimeter has been incorporated. The dose distribution is derived from the images of visible light transmittance, detected with a CCD camera before and after the gel exposure. The analysis was carried out on a single IMRT field chosen among those archived at the Istituto Nazionale Tumori of Milan. The radiation field was examined in an area common to both dosimeters. The agreement between the two detectors was good, as shown by analysis of dose profiles, especially for doses above 15-20 cGy. Gel dosimeter was in good agreement with the planned dose too, with a percentage of dosimeter points passing a dose to agreement test ranging between 90% and 93%. Although preliminary, our data suggest that gel dosimetry is a reliable method for IMRT dose verification. Due to the good spatial resolution and to the tissue equivalent properties of its composition, it would be suitable also for 3D IMRT dose reconstruction and verification in the form of multiple piled-up gel layers.

  20. Gel-layer dosimetry for dose verification in intensity-modulated radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Tomatis, S.; Carrara, M. [Istituto Nazionale Tumori, Via Venezian 1, Milan 20133 (Italy); Gambarini, G. [Physics Department of University of Milan and INFN - National Institute of Nuclear Physics, Via Celoria 16, Milan 20133 (Italy)], E-mail: grazia.gambarini@mi.infn.it; Marchesini, R. [Istituto Nazionale Tumori, Via Venezian 1, Milan 20133 (Italy); Valente, M. [Physics Department of University of Milan and INFN - National Institute of Nuclear Physics, Via Celoria 16, Milan 20133 (Italy)

    2007-09-21

    Intensity-modulated radiotherapy (IMRT) is a technique in which the radiation fluence within each of the treatment beams is not uniformly distributed. This allows the patient dose to follow the boundaries even of a target volume of complex shape, and, virtually, to spare critical healthy organs at risk. The agreement between planned and delivered IMRT dose is verified by means of standard dosimetric methods such as film dosimetry or semiconductors array dosimetry. In this paper, we compare the output of a commercial device using an array of diodes for IMRT absolute dose verification with the output of a gel dosimeter, composed by a 10x8 cm{sup 2} rectangular layer of a tissue-equivalent gel matrix in which a proper chemical dosimeter has been incorporated. The dose distribution is derived from the images of visible light transmittance, detected with a CCD camera before and after the gel exposure. The analysis was carried out on a single IMRT field chosen among those archived at the Istituto Nazionale Tumori of Milan. The radiation field was examined in an area common to both dosimeters. The agreement between the two detectors was good, as shown by analysis of dose profiles, especially for doses above 15-20 cGy. Gel dosimeter was in good agreement with the planned dose too, with a percentage of dosimeter points passing a dose to agreement test ranging between 90% and 93%. Although preliminary, our data suggest that gel dosimetry is a reliable method for IMRT dose verification. Due to the good spatial resolution and to the tissue equivalent properties of its composition, it would be suitable also for 3D IMRT dose reconstruction and verification in the form of multiple piled-up gel layers.

  1. Replanning During Intensity Modulated Radiation Therapy Improved Quality of Life in Patients With Nasopharyngeal Carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Yang Haihua [Department of Radiation Oncology, Laboratory of Cellular and Molecular Radiation Oncology, Taizhou Hospital, Wenzhou Medical College, Taizhou, Zhejiang Province (China); Hu Wei, E-mail: huw@enzemed.com [Department of Radiation Oncology, Laboratory of Cellular and Molecular Radiation Oncology, Taizhou Hospital, Wenzhou Medical College, Taizhou, Zhejiang Province (China); Wang Wei; Chen Peifang; Ding Weijun [Department of Radiation Oncology, Laboratory of Cellular and Molecular Radiation Oncology, Taizhou Hospital, Wenzhou Medical College, Taizhou, Zhejiang Province (China); Luo Wei [Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky (United States)

    2013-01-01

    Purpose: Anatomic and dosimetric changes have been reported during intensity modulated radiation therapy (IMRT) in patients with nasopharyngeal carcinoma (NPC). The purpose of this study was to evaluate the effects of replanning on quality of life (QoL) and clinical outcomes during the course of IMRT for NPC patients. Methods and Materials: Between June 2007 and August 2011, 129 patients with NPC were enrolled. Forty-three patients received IMRT without replanning, while 86 patients received IMRT replanning after computed tomography (CT) images were retaken part way through therapy. Chinese versions of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 and Head and Neck Quality of Life Questionnaire 35 were completed before treatment began and at the end of treatment and at 1, 3, 6, and 12 months after the completion of treatment. Overall survival (OS) data were compared using the Kaplan-Meier method. Results: IMRT replanning had a profound impact on the QoL of NPC patients, as determined by statistically significant changes in global QoL and other QoL scales. Additionally, the clinical outcome comparison indicates that replanning during IMRT for NPC significantly improved 2-year local regional control (97.2% vs 92.4%, respectively, P=.040) but did not improve 2-year OS (89.8% vs 82.2%, respectively, P=.475). Conclusions: IMRT replanning improves QoL as well as local regional control in patients with NPC. Future research is needed to determine the criteria for replanning for NPC patients undergoing IMRT.

  2. Beam orientation optimization for intensity modulated radiation therapy using adaptive l2,1-minimization

    Science.gov (United States)

    Jia, Xun; Men, Chunhua; Lou, Yifei; Jiang, Steve B.

    2011-10-01

    Beam orientation optimization (BOO) is a key component in the process of intensity modulated radiation therapy treatment planning. It determines to what degree one can achieve a good treatment plan in the subsequent plan optimization process. In this paper, we have developed a BOO algorithm via adaptive l2, 1-minimization. Specifically, we introduce a sparsity objective function term into our model which contains weighting factors for each beam angle adaptively adjusted during the optimization process. Such an objective function favors a small number of beam angles. By optimizing a total objective function consisting of a dosimetric term and the sparsity term, we are able to identify unimportant beam angles and gradually remove them without largely sacrificing the dosimetric objective. In one typical prostate case, the convergence property of our algorithm, as well as how beam angles are selected during the optimization process, is demonstrated. Fluence map optimization (FMO) is then performed based on the optimized beam angles. The resulting plan quality is presented and is found to be better than that of equiangular beam orientations. We have further systematically validated our algorithm in the contexts of 5-9 coplanar beams for five prostate cases and one head and neck case. For each case, the final FMO objective function value is used to compare the optimized beam orientations with the equiangular ones. It is found that, in the majority of cases tested, our BOO algorithm leads to beam configurations which attain lower FMO objective function values than those of corresponding equiangular cases, indicating the effectiveness of our BOO algorithm. Superior plan qualities are also demonstrated by comparing DVH curves between BOO plans and equiangular plans.

  3. Intensity modulated radiation therapy and chemotherapy for locally advanced pancreatic cancer: Results of feasibility study

    Institute of Scientific and Technical Information of China (English)

    Yong-Rui Bai; Guo-Hua Wu; Wei-Jian Guo; Xu-Dong Wu; Yuan Yao; Yin Chen; Ren-Hua Zhou; Dong-Qin Lu

    2003-01-01

    AIM: To explore whether intensity modulated radiation therapy (IMRT) in combination with chemotherapy could increase radiation dose to gross tumor volume without severe acute radiation related toxicity by decreasing the dose to the surrounding normal tissue in patients with locally advanced pancreatic cancer.METHODS: Twenty-one patients with locally advanced pancreatic cancer were evaluated in this clinical trial,Patients would receive the dose of IMRT from 21Gy to 30Gy in 7 to 10 fractions within two weeks after conventional radiotherapy of 30Gy in 15 fractions over 3 weeks. The total escalation tumor dose would be 51, 54,57, 60Gy, respectively. 5-fluororacil (5-FU) or gemcitabine was given concurrently with radiotherapy during the treatment course.RESULTS: Sixteen patients who had completed the radiotherapy plan with doses of 51Gy (3 cases), 54Gy (3 cases), 57Gy (3 cases) and 60Gy (7 cases) were included for evaluation. The median levels of CA19-9 prior to and after radiotherapy were 716 U/ml and 255 U/ml respectively (P<0.001) in 13 patients who demonstrated high levels of CA19-9 before radiotherapy. Fourteen patients who suffered from pain could reduce at least 1/3-1/2 amount of analgesic intake and 5 among these patients got complete relief of pain. Ten patients improved in Kamofsky performance status (KPS). The median follow-up period was 8 months and one-year survival rate was 35 %. No patient suffered more than grade Ⅲ acute toxicities induced by radiotherapy.CONCLUSION: Sixty Gy in 25 fractions over 5 weeks with late course IMRT technique combined with concurrent 5-FU chemotherapy can provide a definitely palliative benefit with tolerable acute radiation related toxicity for patients with advanced pancreatic cancer.

  4. Gamma evaluation combined with isocenter optimal matching in intensity modulated radiation therapy quality assurance

    Science.gov (United States)

    Bak, Jino; Choi, Jin Hwa; Park, Suk Won; Park, Kwangwoo; Park, Sungho

    2015-12-01

    Two-dimensional (2D) dose comparisons are widely performed by using a gamma evaluation with patient-specific intensity modulated radiation therapy quality assurance (IMRT QA) or dose delivery quality assurance (DQA). In this way, a pass/fail determination is made for a particular treatment plan. When gamma evaluation results are close to the failure criterion, the pass/fail decision may change applying a small shift to the center of the 2D dose distribution. In this study, we quantitatively evaluated the meaning of such a small relative shift in a 2D dose distribution comparison. In addition, we propose the use of a small shift for a pass/fail criterion in gamma analysis, where the concept of isocenter optimal matching (IOM) is applied to IMRT QA of 20 patients. Gamma evaluations were performed to compare two dose distributions, one with and the other without IOM. In-house software was developed in C++ in order to find IOM values including both translational and rotational shifts. Upon gamma evaluation failure, further investigation was initiated using IOM. In this way, three groups were categorized: group 1 for `pass' on gamma evaluation, group 21 for `fail' on the gamma evaluation and `pass' on the gamma the evaluation with IOM, and group 22 for `fail' on the both gamma evaluations and the IOM calculation. IOM results revealed that some failures could be considered as a `pass'. In group 21, 88.98% (fail) of the averaged gamma pass rate changed to 90.45% (pass) when IOM was applied. On average, a ratio of γ ≥ 1 was reduced by 11.06% in 20 patients. We propose that gamma evaluations that do not pass with a rate of 85% to 90% may be augmented with IOM to reveal a potential pass result.

  5. Patterns of Disease Recurrence Following Treatment of Oropharyngeal Cancer With Intensity Modulated Radiation Therapy

    International Nuclear Information System (INIS)

    Purpose: To report mature results of a large cohort of patients diagnosed with squamous cell carcinoma of the oropharynx who were treated with intensity modulated radiation therapy (IMRT). Methods and Materials: The database of patients irradiated at The University of Texas, M.D. Anderson Cancer Center was searched for patients diagnosed with oropharyngeal cancer and treated with IMRT between 2000 and 2007. A retrospective review of outcome data was performed. Results: The cohort consisted of 776 patients. One hundred fifty-nine patients (21%) were current smokers, 279 (36%) former smokers, and 337 (43%) never smokers. T and N categories and American Joint Committee on Cancer group stages were distributed as follows: T1/x, 288 (37%); T2, 288 (37%); T3, 113 (15%); T4, 87 (11%); N0, 88(12%); N1/x, 140 (18%); N2a, 101 (13%); N2b, 269 (35%); N2c, 122 (16%); and N3, 56 (7%); stage I, 18(2%); stage II, 40(5%); stage III, 150(19%); and stage IV, 568(74%). Seventy-one patients (10%) presented with nodes in level IV. Median follow-up was 54 months. The 5-year overall survival, locoregional control, and overall recurrence-free survival rates were 84%, 90%, and 82%, respectively. Primary site recurrence developed in 7% of patients, and neck recurrence with primary site control in 3%. We could only identify 12 patients (2%) who had locoregional recurrence outside the high-dose target volumes. Poorer survival rates were observed in current smokers, patients with larger primary (T) tumors and lower neck disease. Conclusions: Patients with oropharyngeal cancer treated with IMRT have excellent disease control. Locoregional recurrence was uncommon, and most often occurred in the high dose volumes. Parotid sparing was accomplished in nearly all patients without compromising tumor coverage

  6. Prognostic Value of Prevertebral Space Involvement in Nasopharyngeal Carcinoma Based on Intensity-Modulated Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: To investigate the prognostic significance of prevertebral space involvement (PSI) in patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT). Methods and Materials: A retrospective review of data from 506 biopsy-proven, nonmetastatic NPCs was performed. Patients underwent magnetic resonance imaging examinations and received IMRT as their primary treatment. Results: In this series, 161 NPC patients (31.8%) had PSI. Parapharyngeal space (p < 0.001), skull base (p < 0.001), and paranasal sinuses (p = 0.009) were associated with PSI after multivariate analysis. The 4-year overall survival (OS), local relapse-free survival (LRFS), distant metastasis–free survival (DMFS) for NPC patients with and without PSI was 69.1% and 89.2% (p < 0.0001), 83.9% and 96.4% (p < 0.0001), and 71.6% and 89.6% (p < 0.0001), respectively. Multivariate analysis identified PSI as an independent negative prognostic factor for both OS (HR = 1.478–4.380; p = 0.001) and DMFS (HR = 1.389–4.174; p = 0.002). Patients with PSI had similar survival rates in OS and DMFS (p = 0.241 and p = 0.493, respectively) to that of T4 disease, while the differences between PSI and T3 disease in both OS and DMFS were distinctly significant (p = 0.029 and p = 0.029, respectively). Conclusions: For NPC patients treated with IMRT, PSI was found to be an independent prognostic factor for both OS and DMFS. It seems reasonable that PSI should be classified as a T4 disease on the basis of the current American Joint Committee on Cancer staging classification criteria.