![]() The mechanical sag during gantry rotation was dependent on the gantry angle and was larger in the in-plane direction, although the patterns were notĪn initial study on the estimation of time-varying volumetric treatment images and 3D tumor localization from single MV cine EPID imagesĮnergy Technology Data Exchange (ETDEWEB) The Gamma evaluation (3%, 3 mm) technique was used to investigate the improvement in alignment of cine EPID images of a fixed field, by comparing both individual images and the sum of images in a series with the reference gantry zero image. The generalized shift patterns were derived from the data and used in an image registration algorithm to correct for the effect of the mechanical sag in the system. The results were monitored for one linear accelerator over a course of 15 months and six other linear-accelerators from two treatment centers were also investigated using this method. The method was applied to compare the effect in clockwise and counter clockwise gantry rotations and different source-to-detector distances (SDDs). The algorithm results were then tested against independent methods. The markers were tracked in EPID images and a robust in-house developed MATLAB code was used to analyse the images and find the EPID sag in three directions as well as the EPID + gantry sag by comparison to the reference gantry zero image. EPID images were acquired during a 360° gantry rotation in cine imaging mode. Three metallic ball bearings were used as markers in the beam: two of them fixed to the gantry head and the third positioned at the isocenter. In this study, an easy experiment setup and accurate algorithm have been introduced to characterize and correct for the effect of EPID and gantry sag during arc delivery. Several studies have investigated the effects of gravity on the sag of these systems but each have limitations. The application of EPIDs for dosimetry in arc treatments requires accurate characterization of the mechanical sag of the EPID and gantry during rotation. Rowshanfarzad, Pejman Sabet, Mahsheed O'Connor, Daryl J McCowan, Peter M McCurdy, Boyd M C Greer, Peter BĮlectronic portal imaging devices ( EPIDs) have been studied and used for pretreatment and in-vivo dosimetry applications for many years. The content published on the site serves only the interests of its authors and not those of 3D printer brands who also wish to control the 3D modeling market.Detection and correction for EPID and gantry sag during arc delivery using cine EPID imaging. Almost all of the site's revenues are paid back to the platform's makers. Sharing and downloading on Cults3D guarantees that designs remain in makers community hands! And not in the hands of the 3D printing or software giants who own the competing platforms and exploit the designs for their own commercial interests.Ĭults3D is an independent, self-financed site that is not accountable to any investor or brand. ![]() WORD OF MOUTH: Invite your friends to come, discover the platform and the magnificent 3D files shared by the community! Here are 4 solutions accessible to all:ĪDVERTISING: Disable your banner blocker (AdBlock, …) and click on our banner ads.ĪFFILIATION: Make your purchases online by clicking on our affiliate links here Amazon.ĭONATE: If you want, you can make a donation via Ko-Fi □. You like Cults and you want to help us continue the adventure independently? Please note that we are a small team of 3 people, therefore it is very simple to support us to maintain the activity and create future developments.
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