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

{"title":"Dose and linear energy transfer distributions of primary and secondary particles in carbon ion radiation therapy: A Monte Carlo simulation study in water","authors":"Daniel A Johnson, Yong Chen, Salahuddin Ahmad","doi":"10.4103/0971-6203.170785","DOIUrl":"https://doi.org/10.4103/0971-6203.170785","url":null,"abstract":"The factors influencing carbon ion therapy can be predicted from accurate knowledge about the production of secondary particles from the interaction of carbon ions in water/tissue-like materials, and subsequently the interaction of the secondary particles in the same materials. The secondary particles may have linear energy transfer (LET) values that potentially increase the relative biological effectiveness of the beam. Our primary objective in this study was to classify and quantify the secondary particles produced, their dose averaged LETs, and their dose contributions in the absorbing material. A 1 mm diameter carbon ion pencil beam with energies per nucleon of 155, 262, and 369 MeV was used in a geometry and tracking 4 Monte Carlo simulation to interact in a 27 L water phantom containing 3000 rectangular detector voxels. The dose-averaged LET and the dose contributions of primary and secondary particles were calculated from the simulation. The results of the simulations show that the secondary particles that contributed a major dose component had LETs <100 keV/µm. The secondary particles with LETs >600 keV/µm contributed only <0.3% of the dose.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128063879","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}

{"title":"Derivative based sensitivity analysis of gamma index","authors":"B. Sarkar, A. Pradhan, T. Ganesh","doi":"10.4103/0971-6203.170789","DOIUrl":"https://doi.org/10.4103/0971-6203.170789","url":null,"abstract":"Originally developed as a tool for patient-specific quality assurance in advanced treatment delivery methods to compare between measured and calculated dose distributions, the gamma index (γ) concept was later extended to compare between any two dose distributions. It takes into effect both the dose difference (DD) and distance-to-agreement (DTA) measurements in the comparison. Its strength lies in its capability to give a quantitative value for the analysis, unlike other methods. For every point on the reference curve, if there is at least one point in the evaluated curve that satisfies the pass criteria (e.g., δDD = 1%, δDTA = 1 mm), the point is included in the quantitative score as \"pass.\" Gamma analysis does not account for the gradient of the evaluated curve - it looks at only the minimum gamma value, and if it is <1, then the point passes, no matter what the gradient of evaluated curve is. In this work, an attempt has been made to present a derivative-based method for the identification of dose gradient. A mathematically derived reference profile (RP) representing the penumbral region of 6 MV 10 cm × 10 cm field was generated from an error function. A general test profile (GTP) was created from this RP by introducing 1 mm distance error and 1% dose error at each point. This was considered as the first of the two evaluated curves. By its nature, this curve is a smooth curve and would satisfy the pass criteria for all points in it. The second evaluated profile was generated as a sawtooth test profile (STTP) which again would satisfy the pass criteria for every point on the RP. However, being a sawtooth curve, it is not a smooth one and would be obviously poor when compared with the smooth profile. Considering the smooth GTP as an acceptable profile when it passed the gamma pass criteria (1% DD and 1 mm DTA) against the RP, the first and second order derivatives of the DDs (δD', δD\") between these two curves were derived and used as the boundary values for evaluating the STTP against the RP. Even though the STTP passed the simple gamma pass criteria, it was found failing at many locations when the derivatives were used as the boundary values. The proposed derivative-based method can identify a noisy curve and can prove to be a useful tool for improving the sensitivity of the gamma index.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129063238","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}

{"title":"Topics in Accelerator Health Physics: HPS Professional Development School Proceedings","authors":"M. Mackenzie","doi":"10.4103/0971-6203.56082","DOIUrl":"https://doi.org/10.4103/0971-6203.56082","url":null,"abstract":"","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124600692","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}

{"title":"The handbook of physics in diagnostic imaging","authors":"KN Govinda Rajan","doi":"10.4103/0971-6203.42769","DOIUrl":"https://doi.org/10.4103/0971-6203.42769","url":null,"abstract":"","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127465243","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}

{"title":"Obituary","authors":"P. Iyer","doi":"10.1016/S0140-6736(89)91423-2","DOIUrl":"https://doi.org/10.1016/S0140-6736(89)91423-2","url":null,"abstract":"","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129300576","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}

{"title":"News and Events","authors":"T. Ganesh","doi":"10.1057/udi.1997.36","DOIUrl":"https://doi.org/10.1057/udi.1997.36","url":null,"abstract":"","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":" 97","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120829632","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}

{"title":"Synopses of Oral Papers","authors":"K. Dinshaw","doi":"10.4103/0971-6203.28175","DOIUrl":"https://doi.org/10.4103/0971-6203.28175","url":null,"abstract":"IMRT plans by using 6 MV photon beam. For the first and second plans A comparative study of three coplanar IMRT plans for fatty we used 5 fields. The gantry angles were 35°, 100°, 180°, 270° and prostate patients by using pinnacle 3-D treatment planning 325° and 0°, 75°, 135°, 225° and 285° respectively; with couch angle 0°. The third plan had 7 fields for which the gantry angles were 0°, Suvendu Sahoo, AK Rath, NK Painuly, BK Mohanta, H Mod*, 51°, 102°, 153°, 204°, 255° and 306° with couch angle 0°. ICRU 50 S Pattnaik*. Dept. of Medical Physics and *Radiation Oncology, recommendation was followed for the contouring of CTV and other Hemalata Hospitals and Research Center, Bhubaneswar, Orissa, India critical structures. The PTV was generated from CTV having 5 mm 3D­ marigin. The critical structures taken were rectum, bladder and the Introduction: For localized prostate cancer; radiation therapy is an femoral heads. Our study has compared three plans on the basis of effective modality. Prostate is one of the sites that is well suited for dose volume histograms (DVH) of all parameters like PTV and other all IMRT. IMRT planning and treatment delivery show significant potential critical structures. for further improving the therapeutic ratio and reducing toxicity and Results and Discussion: The effect of number of beams in IMRT thereby improving the quality of life. It is the responsibility of the planning for fatty cases is an important decision for a planner. The medical physicist (planner) to obtain an optimal IMRT plan. The purpose mean data of DVH of 5 patients for 3 IMRT plans are given in the of this study is to highlight some important points that need to be Tables. It was seen that, out of the three plans; the third plan was taken care of before embarking upon the IMRT plan. These are: (A) most suitable for patient treatment because the out side PTV maximum the treatment site (B) the facilities available with machine i.e., number dose was much higher in first two plans and comparatively less in the of photon beams, MLC or mMLC and (C) the patient separation third plan. It was seen that in the case of fatty patients the beam path (thickness) from all sides. Of the above three points; first two points length is more in patient body thereby leading to more deposition of are well known to a planner. We want to highlight the third point i.e., dose in the patient body comparative to Planning Target Volume in 5 the patient thickness, which is an important parameter when planning field plans. But in case of 7 fields plan, due to more number of beams IMRT for prostate cancer. Our objective is to show by comparing three the deposition of dose out side PTV was less thereby delivering the co-planner particular IMRT plans; the effect of numbers of beams maximum dose to planning target volume. from various directions on the final dose distribution. Conclusion: This study states that, for fatty prostate patients the 7 Materials and Methods: Our centre is eq","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121092282","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}

{"title":"A Ph.D. thesis entitled “Dose audit and optimization for radiological and interventional procedures”","authors":"K. Faulkner","doi":"10.4103/0971-6203.39423","DOIUrl":"https://doi.org/10.4103/0971-6203.39423","url":null,"abstract":"","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128746460","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}

{"title":"News and Events","authors":"T. Ganesh","doi":"10.1057/udi.1996.36","DOIUrl":"https://doi.org/10.1057/udi.1996.36","url":null,"abstract":"","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122351991","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}

{"title":"News and Events","authors":"T. Ganesh","doi":"10.1057/udi.1999.25","DOIUrl":"https://doi.org/10.1057/udi.1999.25","url":null,"abstract":"","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125662114","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}