Journal of Medical Physics / Association of Medical Physicists of India最新文献

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Journal of Medical Physics / Association of Medical Physicists of India Pub Date : 2018-09-01 DOI: 10.1057/udi.1997.28

T. Ganesh

引用次数: 0

Gamma Putty dosimetric studies in electron beam 电子束中伽马腻子剂量学研究

Journal of Medical Physics / Association of Medical Physicists of India Pub Date : 2016-07-01 DOI: 10.4103/0971-6203.189480

Aime M. Gloi

{"title":"Gamma Putty dosimetric studies in electron beam","authors":"Aime M. Gloi","doi":"10.4103/0971-6203.189480","DOIUrl":"https://doi.org/10.4103/0971-6203.189480","url":null,"abstract":"Traditionally, lead has been used for field shaping in megavoltage electron beams in radiation therapy. In this study, we analyze the dosimetric parameters of a nontoxic, high atomic number (Z = 83), bismuth-loaded material called Gamma Putty that is malleable and can be easily molded to any desired shape. First, we placed an ionization chamber at different depths in a solid water phantom under a Gamma Putty shield of thickness (t = 0, 3, 5, 10, 15, 20, and 25 mm, respectively) and measured the ionizing radiation on the central axis (CAX) for electron beam ranging in energies from 6 to 20 MeV. Next, we investigated the relationship between the relative ionization (RI) measured at a fixed depth for several Gamma Putty shield at different cutout diameters ranging from 2 to 5 cm for various beam energies and derived an exponential fitting equation for clinical purposes. The dose profiles along the CAX show that bremsstrahlung dominates for Gamma Putty thickness >15 mm. For high-energy beams (12-20 MeV) and all Gamma Putty thicknesses up to 25 mm, RI below 5% could not be achieved due to the strong bremsstrahlung component. However, Gamma Putty is a very suitable material for reducing the transmission factor below 5% and protecting underlying normal tissues for low-energy electron beams (6-9 MeV).","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122395361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Dosimetric and radiobiological characterizations of prostate intensity-modulated radiotherapy and volumetric-modulated arc therapy: A single-institution review of ninety cases 前列腺调强放疗和体积调节电弧治疗的剂量学和放射生物学特征:一项对90例病例的单一机构回顾

Journal of Medical Physics / Association of Medical Physicists of India Pub Date : 2016-07-01 DOI: 10.4103/0971-6203.189479

Muhammad Isa Khan, R. Jiang, A. Kiciak, Jalil ur Rehman, M. Afzal, J. Chow

{"title":"Dosimetric and radiobiological characterizations of prostate intensity-modulated radiotherapy and volumetric-modulated arc therapy: A single-institution review of ninety cases","authors":"Muhammad Isa Khan, R. Jiang, A. Kiciak, Jalil ur Rehman, M. Afzal, J. Chow","doi":"10.4103/0971-6203.189479","DOIUrl":"https://doi.org/10.4103/0971-6203.189479","url":null,"abstract":"This study reviewed prostate volumetric-modulated arc therapy (VMAT) plans with intensity-modulated radiotherapy (IMRT) plans after prostate IMRT technique was replaced by VMAT in an institution. Characterizations of dosimetry and radiobiological variation in prostate were determined based on treatment plans of 40 prostate IMRT patients (planning target volume = 77.8-335 cm 3 ) and 50 VMAT patients (planning target volume = 120-351 cm 3 ) treated before and after 2013, respectively. Both IMRT and VMAT plans used the same dose-volume criteria in the inverse planning optimization. Dose-volume histogram, mean doses of target and normal tissues (rectum, bladder and femoral heads), dose-volume points (D 99% of planning target volume; D 30% , D 50% , V 30 Gy and V 35 Gy of rectum and bladder; D 5% , V 14 Gy , V 22 Gy of femoral heads), conformity index (CI), homogeneity index (HI), gradient index (GI), prostate tumor control probability (TCP), and rectal normal tissue complication probability (NTCP) based on the Lyman-Burman-Kutcher algorithm were calculated for each IMRT and VMAT plan. From our results, VMAT plan was found better due to its higher (1.05%) CI, lower (0.83%) HI and (0.75%) GI than IMRT. Comparing doses in normal tissues between IMRT and VMAT, it was found that IMRT mostly delivered higher doses of about 1.05% to the normal tissues than VMAT. Prostate TCP and rectal NTCP were found increased (1%) for VMAT than IMRT. It is seen that VMAT technique can decrease the dose-volume evaluation criteria for the normal tissues. Based on our dosimetric and radiobiological results in treatment plans, it is concluded that our VMAT implementation could produce comparable or slightly better target coverage and normal tissue sparing with a faster treatment time in prostate radiotherapy.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122571156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 22

Comparative study of old and new versions of treatment planning system using dose volume histogram indices of clinical plans 应用临床计划剂量体积直方图指标的新旧治疗计划系统比较研究

Journal of Medical Physics / Association of Medical Physicists of India Pub Date : 2016-07-01 DOI: 10.4103/0971-6203.189489

G. S. Krishna, V. Srinivas, K. Ayyangar, P. Y. Reddy

{"title":"Comparative study of old and new versions of treatment planning system using dose volume histogram indices of clinical plans","authors":"G. S. Krishna, V. Srinivas, K. Ayyangar, P. Y. Reddy","doi":"10.4103/0971-6203.189489","DOIUrl":"https://doi.org/10.4103/0971-6203.189489","url":null,"abstract":"Recently, Eclipse treatment planning system (TPS) version 8.8 was upgraded to the latest version 13.6. It is customary that the vendor gives training on how to upgrade the existing software to the new version. However, the customer is provided less inner details about changes in the new software version. According to manufacturer, accuracy of point dose calculations and irregular treatment planning is better in the new version (13.6) compared to the old version (8.8). Furthermore, the new version uses voxel-based calculations while the earlier version used point dose calculations. Major difference in intensity-modulated radiation therapy (IMRT) plans was observed between the two versions after re-optimization and re-calculations. However, minor difference was observed for IMRT cases after performing only re-calculations. It is recommended TPS quality assurance to be performed after any major upgrade of software. This can be done by performing dose calculation comparisons in TPS. To assess the difference between the versions, 25 clinical cases from the old version were compared keeping all the patient data intact including the monitor units and comparing the differences in dose calculations using dose volume histogram (DVH) analysis. Along with DVH analysis, uniformity index, conformity index, homogeneity index, and dose spillage index were also compared for both versions. The results of comparative study are presented in this paper.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124803530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 11

Radiological risk assessment of cosmic radiation at aviation altitudes (a trip from Houston Intercontinental Airport to Lagos International Airport) 航空高度宇宙辐射的辐射风险评估(从休斯顿洲际机场到拉各斯国际机场的行程)

Journal of Medical Physics / Association of Medical Physicists of India Pub Date : 2016-07-01 DOI: 10.4103/0971-6203.189491

P. Enyinna

引用次数: 7

Radioprotective effects of hesperidin on oxidative damages and histopathological changes induced by X-irradiation in rats heart tissue 橙皮苷对x射线致大鼠心脏组织氧化损伤及组织病理改变的辐射防护作用

Journal of Medical Physics / Association of Medical Physicists of India Pub Date : 2016-07-01 DOI: 10.4103/0971-6203.189482

A. Rezaeyan, G. Haddadi, Massood Hosseinzadeh, M. Moradi, M. Najafi

{"title":"Radioprotective effects of hesperidin on oxidative damages and histopathological changes induced by X-irradiation in rats heart tissue","authors":"A. Rezaeyan, G. Haddadi, Massood Hosseinzadeh, M. Moradi, M. Najafi","doi":"10.4103/0971-6203.189482","DOIUrl":"https://doi.org/10.4103/0971-6203.189482","url":null,"abstract":"This study was carried out to evaluate radioprotective effects of hesperidin (HES) administration before the irradiation on the cardiac oxidative stress and histopathological changes in an experimental rat model. The cardiovascular complications of radiation exposure cause morbidity and mortality in patients who received radiotherapy. HES, an antioxidant flavonoid found in citrus fruits, suggests the protection against the tissue damage. Fifty-eight rats were divided into four groups: Group 1 received phosphate buffered saline (PBS) and sham radiation; Group 2, HES and sham radiation; Group 3, PBS and radiation; and Group 4, HES and radiation. The rats were exposed to single dose of 18 Gy of 6 MV X-ray. One hundred milligrams per kilogram doses of HES was administered for 7 days before irradiation. The estimation of superoxide dismutase (SOD), malondialdehyde (MDA), and histopathological analyses was performed at 24 h and 8 weeks after radiation exposure. The irradiation of chest area resulted in an elevated MDA level and decreased SOD activity. Moreover, long-term pathological lesions of radiation were inflammation, fibrosis, the increased number of mast cells and macrophages, and development of plaque, vascular leakage, myocardial degeneration, and myocyte necrosis. Although the administration of HES decreases inflammation, fibrosis, mast cell and macrophage numbers, and myocyte necrosis, it did not result in reduced thrombus, myocardium degeneration, and vascular leakage. In conclusion, these results suggest that HES can perform a radioprotection action. The protective effect of HES may be attributable to its immunomodulatory effects and free radical-scavenging properties.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134576274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 42

Medical physics aspects in accreditation of radiation oncology practice 放射肿瘤学实践认证的医学物理方面

Journal of Medical Physics / Association of Medical Physicists of India Pub Date : 2016-07-01 DOI: 10.4103/0971-6203.189452

S. Rustgi

引用次数: 2

Analysis of dose distribution in organs at risk in patients with prostate cancer treated with the intensity-modulated radiation therapy and arc technique 调强放疗和电弧技术治疗前列腺癌患者危险器官的剂量分布分析

Journal of Medical Physics / Association of Medical Physicists of India Pub Date : 2016-07-01 DOI: 10.4103/0971-6203.189490

Michał Biegała, A. Hydzik

{"title":"Analysis of dose distribution in organs at risk in patients with prostate cancer treated with the intensity-modulated radiation therapy and arc technique","authors":"Michał Biegała, A. Hydzik","doi":"10.4103/0971-6203.189490","DOIUrl":"https://doi.org/10.4103/0971-6203.189490","url":null,"abstract":"This study describes a comparative analysis of treatment plans in 48 patients with prostate cancer treated with ionizing radiation. Each patient was subjected to the intensity-modulated radiation therapy (IMRT) and arc technique. In each treatment plan, the organs at risk were assessed: the urinary bladder, rectum and heads of the femur, as well as the volume of normal tissue. The following features were compared: treatment time, conformity indices for the planning target volume, mean doses and standard deviation in organs at risk, and organ volumes for each particular dose. The treatment period in the arc technique is 13.7% shorter than in the IMRT technique. Comparing the results of the IMRT and arc techniques (arc vs. IMRT), the mean values were 29.21 ± 12.91 Gy versus 28.36 ± 13.79 Gy for the bladder, 20.36 ± 3.16 Gy versus 18.17 ± 5.11 Gy for the right femoral head, and 18.98 ± 3.28 Gy versus 16.67 ± 5.15 Gy for the left femoral head. For the rectum, lower values were obtained after application of the arc technique, not the IMRT technique: 35.84 ± 12.28 Gy versus 35.90 ± 13.05 Gy. The results indicate that the applied therapy has a statistically significant influence on the volume for a particular dose with regard to the urinary bladder. It is advisable to apply the IMRT technique to patients who need the femur heads and urinary bladder protected by exposing them to low irradiation doses.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"224 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114428210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Investigation of grid performance using simple image quality tests 使用简单的图像质量测试调查网格性能

Journal of Medical Physics / Association of Medical Physicists of India Pub Date : 2016-01-01 DOI: 10.4103/0971-6203.177280

D. Bor, O. Birgul, Umran Onal, T. Olgar

{"title":"Investigation of grid performance using simple image quality tests","authors":"D. Bor, O. Birgul, Umran Onal, T. Olgar","doi":"10.4103/0971-6203.177280","DOIUrl":"https://doi.org/10.4103/0971-6203.177280","url":null,"abstract":"Antiscatter grids improve the X-ray image contrast at a cost of patient radiation doses. The choice of appropriate grid or its removal requires a good knowledge of grid characteristics, especially for pediatric digital imaging. The aim of this work is to understand the relation between grid performance parameters and some numerical image quality metrics for digital radiological examinations. The grid parameters such as bucky factor (BF), selectivity (Σ), Contrast improvement factor (CIF), and signal-to-noise improvement factor (SIF) were determined following the measurements of primary, scatter, and total radiations with a digital fluoroscopic system for the thicknesses of 5, 10, 15, 20, and 25 cm polymethyl methacrylate blocks at the tube voltages of 70, 90, and 120 kVp. Image contrast for low- and high-contrast objects and high-contrast spatial resolution were measured with simple phantoms using the same scatter thicknesses and tube voltages. BF and SIF values were also calculated from the images obtained with and without grids. The correlation coefficients between BF values obtained using two approaches (grid parameters and image quality metrics) were in good agreement. Proposed approach provides a quick and practical way of estimating grid performance for different digital fluoroscopic examinations.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"208 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114757516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10

Evaluation of various boluses in dose distribution for electron therapy of the chest wall with an inward defect 胸壁内缺陷电子治疗不同剂量分布的评价

Journal of Medical Physics / Association of Medical Physicists of India Pub Date : 2016-01-01 DOI: 10.4103/0971-6203.177288

Hoda Mahdavi, K. Jabbari, M. Roayaei

{"title":"Evaluation of various boluses in dose distribution for electron therapy of the chest wall with an inward defect","authors":"Hoda Mahdavi, K. Jabbari, M. Roayaei","doi":"10.4103/0971-6203.177288","DOIUrl":"https://doi.org/10.4103/0971-6203.177288","url":null,"abstract":"Delivering radiotherapy to the postmastectomy chest wall can be achieved using matched electron fields. Surgical defects of the chest wall change the dose distribution of electrons. In this study, the improvement of dose homogeneity using simple, nonconformal techniques of thermoplastic bolus application on a defect is evaluated. The proposed phantom design improves the capability of film dosimetry for obtaining dose profiles of a patient's anatomical condition. A modeled electron field of a patient with a postmastectomy inward surgical defect was planned. High energy electrons were delivered to the phantom in various settings, including no bolus, a bolus that filled the inward defect (PB0), a uniform thickness bolus of 5 mm (PB1), and two 5 mm boluses (PB2). A reduction of mean doses at the base of the defect was observed by any bolus application. PB0 increased the dose at central parts of the defect, reduced hot areas at the base of steep edges, and reduced dose to the lung and heart. Thermoplastic boluses that compensate a defect (PB0) increased the homogeneity of dose in a fixed depth from the surface; adversely, PB2 increased the dose heterogeneity. This study shows that it is practical to investigate dose homogeneity profiles inside a target volume for various techniques of electron therapy.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122456349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6