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A Simple Method for Verification of HDR Brachytherapy Source Position Inside Applicators Using An Electron Beam From a Linear Accelerator

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Y Kakinohana

Y Kakinohana*, T Toita , T Ariga , H Maemoto , T Kusada , S Hasimoto , J Heiannna , S Murayama , University of the Ryukyus, Nishihara-cho, Okinawa


SU-I-GPD-T-21 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: In high dose rate brachytherapy (HDR), accurate source dwell positions are needed to ensure that the treatment proceeds as planned. Verification of the source dwell position is an important step in HDR quality assurance (QA) procedures.Approaches to verify the position of a HDR brachytherapy source have been reported as part of QA procedures, but most of the reports have been performed using quality assurance devices and have assumed that the dwell position in the quality devices are the same as in treatment applicators. However, the QA devices differ in their shape from the treatment applicators. Generally, QA devices have straight rod-like structure but most applicators are curvature structure. Therefore, the source positions inside the treatment applicators may differ from that in QA devices. It would be useful to image the source positions inside the applicators for verification offset position. The aim of this work is to demonstrate a simple method for direct visualization of the source position inside the applicators using an electron beam from a radiotherapy linear accelerator

Methods: A metal applicator for HDR brachytherapy (Nucletron) was taped onto a strip of radiochromic film (Gafchromic, EBT3). Then the film with the applicator was moved to the radiotherapy room to irradiate by an electron beam. The film was irradiated by a 15 MeV electron beam with dose of 2Gy. The applicator was imaged on the film. After irradiation, the film was moved to the brachytherapy room and exposed to the Ir-192 source running the QA program.

Results: The result is a superimposed image of the source positions and applicator structure. This method enables easily verification of the source positions inside the applicator and the offset distance.

Conclusion: This method enables easily visual verification of the source positions inside the applicator and the offset distance.

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