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

{"title":"In regard to “Setup error analysis in helical tomotherapy based image-guided radiation therapy treatments”","authors":"S. Yartsev","doi":"10.4103/0971-6203.177275","DOIUrl":"https://doi.org/10.4103/0971-6203.177275","url":null,"abstract":"Sir, I read with interest the paper of Dr. Thondykandy et al. in the latest issue of your journal.[1] The current rapid introduction of pretreatment (tomotherapy megavoltage computed tomography (CT) and cone-beam CT on Varian and Elekta linacs) and in-treatment (CyberKnife, ViewRay) image guidance (IG) needs a careful assessment of these technologies in order to establish their optimal usage. The authors investigated the position correction shifts for 102 patients treated with helical tomotherapy using megavoltage CT for matching the patient position of the day to the planning CT study. There is no information on how planning CT studies were obtained, but for patients with a significant target motion, the usage of fast helical CT studies for planning may be suboptimal for IG purpose, and untagged average studies should be recommended. Systematic and random errors were evaluated and used for treatment margin calculation as per van Herk et al.[2] However, the authors’ concluded that the clinical margins used in their hospital were adequate enough for the brain, head and neck, and lung cancer patients while being out of clinical margins for the pelvis and cervical spine injury patients, may be confusing. The margins calculated by Thondykandy et al.[1] correspond only to a part of the total planning target volume (PTV) construction accounting for interfraction motion as explained in BIR publication.[3] These margin values can be used to account for positioning errors if no pretreatment IG is performed.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"155 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":"123176908","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":"Dosimetric comparison of three-dimensional conformal radiotherapy, intensity modulated radiotherapy, and helical tomotherapy for lung stereotactic body radiotherapy","authors":"R. Kinhikar, Y. Ghadi, P. Sahoo, S. Laskar, D. Deshpande, S. Shrivastava, J. Agarwal","doi":"10.4103/0971-6203.170792","DOIUrl":"https://doi.org/10.4103/0971-6203.170792","url":null,"abstract":"To compare the treatment plans generated with three-dimensional conformal radiation therapy (3DCRT), intensity modulated radiotherapy (IMRT), and helical tomotherapy (HT) for stereotactic body radiotherapy of lung, twenty patients with medically inoperable (early nonsmall cell lung cancer) were retrospectively reviewed for dosimetric evaluation of treatment delivery techniques (3DCRT, IMRT, and HT). A dose of 6 Gy per fraction in 8 fractions was prescribed to deliver 95% of the prescription dose to 95% volume of planning target volume (PTV). Plan quality was assessed using conformity index (CI) and homogeneity index (HI). Doses to critical organs were assessed. Mean CI with 3DCRT, IMRT, and HT was 1.19 (standard deviation [SD] 0.13), 1.18 (SD 0.11), and 1.08 (SD 0.04), respectively. Mean HI with 3DCRT, IMRT, and HT was 1.14 (SD 0.05), 1.08 (SD 0.02), and 1.07 (SD 0.04), respectively. Mean R50% values for 3DCRT, IMRT, and HT was 8.5 (SD 0.35), 7.04 (SD 0.45), and 5.43 (SD 0.29), respectively. D2cmwas found superior with IMRT and HT. Significant sparing of critical organs can be achieved with highly conformal techniques (IMRT and HT) without compromising the PTV conformity and homogeneity.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"40 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":"128986201","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":"Expanding horizons in medical physics: Standardization to visualization and quantitative assessment based personalized treatments","authors":"B. Paliwal","doi":"10.4103/0971-6203.170795","DOIUrl":"https://doi.org/10.4103/0971-6203.170795","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":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128713258","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":"Impact of dose rate on accuracy of intensity modulated radiation therapy plan delivery using the pretreatment portal dosimetry quality assurance and setting up the workflow at hospital levels","authors":"K. Kaviarasu, N. A. N. Raj, K. Murthy, A. G. Babu, B. D. Prasad","doi":"10.4103/0971-6203.170786","DOIUrl":"https://doi.org/10.4103/0971-6203.170786","url":null,"abstract":"The aim of this study was to examine the impact of dose rate on accuracy of intensity modulated radiation therapy (IMRT) plan delivery by comparing the gamma agreement between the calculated and measured portal doses by pretreatment quality assurance (QA) using electronic portal imaging device dosimetry and creating a workflow for the pretreatment IMRT QA at hospital levels. As the improvement in gamma agreement leads to increase in the quality of IMRT treatment delivery, gamma evaluation was carried out for the calculated and the measured portal images for the criteria of 3% dose difference and 3 mm distance-to-agreement (DTA). Three gamma parameters: Maximum gamma, average gamma, and percentage of the field area with a gamma value>1 .0 were analyzed. Three gamma index parameters were evaluated for 40 IMRT plans (315 IMRT fields) which were calculated for 400 monitor units (MU)/min dose rate and maximum multileaf collimator (MLC) speed of 2.5 cm/s. Gamma parameters for all 315 fields are within acceptable limits set at our center. Further, to improve the gamma results, we set an action level for this study using the mean and standard deviation (SD) values from the 315 fields studied. Forty out of 315 IMRT fields showed low gamma agreement (gamma parameters>2 SD as per action level of the study). The parameters were recalculated and reanalyzed for the dose rates of 300, 400 and 500 MU/min. Lowering the dose rate helped in getting an enhanced gamma agreement between the calculated and measured portal doses of complicated fields. This may be attributed to the less complex motion of MLC over time and the MU of the field/segment. An IMRT QA work flow was prepared which will help in improving the quality of IMRT delivery.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"229 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":"122508848","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":"Reply to the comment of S. VanDyk and K. Narayan on the editorial “IMRT, IGRT and other high technology become standard in external beam radiotherapy: But is image-guided brachytherapy for cervical cancer too expensive?” J Med Phys 2015;40:1-4","authors":"S. Jamema, C. Kirisits","doi":"10.4103/0971-6203.170794","DOIUrl":"https://doi.org/10.4103/0971-6203.170794","url":null,"abstract":"Sir, To begin with, the core point of the editorial (even the title) is about the general issue of the treatment of cervix cancer patients, where the main priority is to establish simple methods, while for other disease sites, the state of the art is constantly improving, especially with external beam methods. The short paragraph that was dedicated to the ultrasound (US) is well deserving, considering that the editorial is not about the US alone, but about the various other issues associated with the image‐based brachytherapy (IGABT) of cervical cancer.","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":"115295462","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":"Evaluation of external beam hardening filters on image quality of computed tomography and single photon emission computed tomography/computed tomography","authors":"Nivedita Rana, D. Rawat, Madan Parmar, D. Dhawan, A. K. Bhati, B. Mittal","doi":"10.4103/0971-6203.170790","DOIUrl":"https://doi.org/10.4103/0971-6203.170790","url":null,"abstract":"This study was undertaken to evaluate the effect of external metal filters on the image quality of computed tomography (CT) and single photon emission computed tomography (SPECT)/CT images. Images of Jaszack phantom filled with water and containing iodine contrast filled syringes were acquired using CT (120 kV, 2.5 mA) component of SPECT/CT system, ensuring fixation of filter on X-ray collimator. Different thickness of filters of Al and Cu (1 mm, 2 mm, 3 mm, and 4 mm) and filter combinations Cu 1 mm, Cu 2 mm, Cu 3 mm each in combination with Al (1 mm, 2 mm, 3 mm, and 4 mm), respectively, were used. All image sets were visually analyzed for streak artifacts and contrast to noise ratio (CNR) was derived. Similar acquisition was done using Philips CT quality control (QC) phantom and CNR were calculated for its lexan, perspex, and teflon inserts. Attenuation corrected SPECT/CT images of Jaszack phantom filled with 444–555 MBq (12–15 mCi) of 99mTc were obtained by applying attenuation correction map generated by hardened X-ray beam for different filter combination, on SPECT data. Uniformity, root mean square (rms) and contrast were calculated in all image sets. Less streak artifacts at iodine water interface were observed in images acquired using external filters as compared to those without a filter. CNR for syringes, spheres, and inserts of Philips CT QC phantom was almost similar to Al 2 mm, Al 3 mm, and without the use of filters. CNR decreased with increasing copper thickness and other filter combinations. Uniformity and rms were lower, and value of contrast was higher for SPECT/CT images when CT was acquired with Al 2 mm and 3 mm filter than for images acquired without a filter. The study suggests that for Infinia Hawkeye 4, SPECT/CT system, Al 2 mm, and 3 mm are the optimum filters for improving image quality of SPECT/CT images of Jaszack or Philips CT QC phantom keeping other parameters of CT constant.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"7 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":"134040068","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":"Inter-departmental dosimetry audits – development of methods and lessons learned","authors":"D. Eaton, S. Bolton, R. Thomas, C. Clark","doi":"10.4103/0971-6203.170791","DOIUrl":"https://doi.org/10.4103/0971-6203.170791","url":null,"abstract":"External dosimetry audits give confidence in the safe and accurate delivery of radiotherapy. In the United Kingdom, such audits have been performed for almost 30 years. From the start, they included clinically relevant conditions, as well as reference machine output. Recently, national audits have tested new or complex techniques, but these methods are then used in regional audits by a peer-to-peer approach. This local approach builds up the radiotherapy community, facilitates communication, and brings synergy to medical physics.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"20 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":"131550201","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":"Use of image guided radiation therapy techniques and imaging dose measurement at Indian hospitals: A survey","authors":"S. Deshpande, D. Dhote, R. Kumar, S. Naidu, A. Sutar, V. Kannan","doi":"10.4103/0971-6203.170788","DOIUrl":"https://doi.org/10.4103/0971-6203.170788","url":null,"abstract":"A national survey was conducted to obtain information about the use of image-guided radiotherapy (IGRT) techniques and IGRT dose measurement methods being followed at Indian radiotherapy centers. A questionnaire containing parameters relevant to use of IGRT was prepared to collect the information pertaining to (i) availability and type of IGRT delivery system, (ii) frequency of image acquisition protocol and utilization of these images for different purpose, and (iii) imaging dose measurement. The questionnaire was circulated to 75 hospitals in the country having IGRT facility, and responses of 51 centers were received. Su rvey results showed that among surveyed hospitals, 86% centers have IGRT facility, 78% centers have kilo voltage three-dimensional volumetric imaging. 75% of hospitals in our study do not perform computed tomography dose index measurements and 89% of centers do not perform patient dose measurements. Moreover, only 29% physicists believe IGRT dose is additional radiation burden to patient. This study has brought into focus the need to design a national protocol for IGRT dose measurement and development of indigenous tools to perform IGRT dose measurements.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"1 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":"122784210","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":"Setup error analysis in helical tomotherapy based image-guided radiation therapy treatments","authors":"Bhagyalakshmi Akkavil Thondykandy, J. Swamidas, J. Agarwal, T. Gupta, S. Laskar, U. Mahantshetty, S. Iyer, Indrani U. Mukherjee, S. Shrivastava, D. Deshpande","doi":"10.4103/0971-6203.170796","DOIUrl":"https://doi.org/10.4103/0971-6203.170796","url":null,"abstract":"The adequacy of setup margins for various sites in patients treated with helical tomotherapy was investigated. A total of 102 patients were investigated. The breakdown of the patients were as follows: Twenty-five patients each in brain, head and neck (H and N), and pelvis, while 12 patients in lung and 15 in craniospinal irradiation (CSI). Patients were immobilized on the institutional protocol. Altogether 2686 megavoltage computed tomography images were analyzed with 672, 747, 622, 333, and 312 fractions, respectively, from brain, H and N, pelvis, lung, and CSI. Overall systematic and random errors were calculated in three translational and three rotational directions. Setup margins were evaluated using van Herk formula. The calculated margins were compared with the margins in the clinical use for various directions and sites. We found that the clinical isotropic margin of 3 mm was adequate for brain patients. However, in the longitudinal direction it was found to be out of margin by 0.7 mm. In H and N, the calculated margins were well within the isotropic margin of 5 mm which is in clinical use. In pelvis, the calculated margin was within the limits, 8.3 mm versus 10 mm only in longitudinal direction, however, in vertical and lateral directions the calculated margins were out of clinical margins 11 mm versus 10 mm, and 8.7 mm versus 7.0, mm respectively. In lung, all the calculated margins were well within the margins used clinically. In CSI, the variation was found in the middle spine in the longitudinal direction. The clinical margins used in our hospital are adequate enough for sites H and N, lung, and brain, however, for CSI and pelvis the margins were found to be out of clinical margins.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"34 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":"133568017","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":"In response to Swamidas and Kirisits","authors":"S. van Dyk, K. Narayan","doi":"10.4103/0971-6203.170793","DOIUrl":"https://doi.org/10.4103/0971-6203.170793","url":null,"abstract":"We were dismayed to read the short and unsatisfactory paragraph discussing the use of transabdominal ultrasound to guide brachytherapy for cervix cancer in an editorial from a country burdened with one‐fifth of all new cases of cervix cancer. We expected a more pragmatic approach from this region given the recognition of the disparity in resource and technology utilization between external beam treatment and brachytherapy in your environment. To say that ultrasound “will certainly play an important role in the future” implies ultrasound has no role in the present, this is both erroneous and mendacious reporting. Two clinical outcome studies using transabdominal ultrasound have been reported in the literature, neither of which were discussed in the editorial.[1,2] These reports have both shown how the use of low cost accessible transabdominal ultrasound can incorporate soft tissue imaging into a brachytherapy program and achieve similar survival rates and late effects as magnetic resonance imaging‐based three‐dimensional planning. It is possible to see the width, height, and thickness of the cervix using transabdominal ultrasound. One just has to turn the transducer through 90°. To caution against the use of ultrasound because technology is not as advanced as desired is extremely self‐limiting. It is not necessary to track the applicator in relation to the ultrasound scan set as the applicator itself acts as a fiducial and calibration device within the image. Transrectal ultrasound (TRUS) is limited by the short focal length (60 mm) and small field of view and while it may be a useful tool to assess cervix tumor width, there are no reports of its use in measuring cervix tumor height in locally advanced cancers. Tumor width, height, and thickness have not been measured with the applicator in situ with TRUS, nor has brachytherapy been planned using these images. At present, two‐dimensional transabdominal ultrasound images, which depict the applicator and anatomy, are used to verify applicator position by many departments around the world and used to guide planning in the two departments mentioned. These two departments have shown that use of transabdominal ultrasound significantly improved the dose distribution for target and OAR in comparison with conventional point X‐ray based planning. In a region where X‐ray based planning is the norm, resources are limited and patients are poor, it behooves us to explore accessible time and cost‐effective solutions and make image‐guided conformal brachytherapy possible for all.","PeriodicalId":143694,"journal":{"name":"Journal of Medical Physics / Association of Medical Physicists of India","volume":"74 5 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":"128049530","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}