ESTRO38 Congress Report

Brachytherapy

1. BrachyView: A Real-time In-body HDR Source Tracking System with Simultaneous TRUS Image Fusion (E38-0696) S. Alnaghy 1 ,D. L. Cutajar 1 , M. Safavi-Naeini 1 ,S. Geroge 1 , A. Howie 2 , A. Bece 2 , J. A. Bucci 2 , J. Jakubek 3 , S. Pospisil 3 , M. L. F. Lerch 1 , M. Petasecca 1 , A. B. Rosenfeld 1 1 Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales, Australia, 2 St George Cancer Care Centre, St George Hospital, Kogarah, New South Wales, Australia, 3 Institute of Experimental and Applied Physics, Czech Technical University of Prague, Prague, Czech Republic

Context of the study High Dose Rate (HDR) brachytherapy is emerging as a promising treatment option for the treatment of nonmetastatic prostate cancer. HDR brachytherapy allows greater dose escalation that can’t be safely achieved with external beam radiation therapy, while delivering less dose to the surrounding organs at risk and therefore offeringmore effective tumour control. One major challenge with HDR Brachytherapy is verification of source positioning within the prostate during treatment. This is a result of changes in prostate anatomy during treatment and accurate catheter placement can be difficult to achieve. The Centre for Medical Radiation Physics at the University of Wollongong have developed a rectal probe, BrachyView, that is capable of real-time source tracking, providing source locations within the anatomy of the prostate during treatment. Overview of abstract The purpose of this work is to present the first clinical evaluation of a world first rectal probe named BrachyView for real-time source verification and dose quality assurance (QA) in HDR Prostate Brachytherapy. The prototype was tested using a patient plan and a tissue equivalent prostate gel phantom. What were the three main findings of your research? 1. The probe was able to reconstruct 78% of the total dwell locations of the HDR source in real-time within 1 mm accuracy. 2. Limitations in read-out speeds of 0.28 sec/frame were found, restricting dwell times to a minimum of 0.3 sec that could be located by the probe. 3. This study shows that the BrachyView system is capable of source localization of HDR source in real-time. What impact could your research have? The BrachyView probe combined with TRUS can provide source position information within the prostate volume in real-time. This information can be used to validate the TSP and allow adjustments in treatment delivery if the source position varies from the TPS. Real-time source monitoring can improve treatment quality of needle implantation and reduce radiation related tissue toxicities to the critical organs at risk (rectum, urethra and bladder). Is this research indicative of a bigger trend in oncology? Radiotherapy is moving towards In-vivo dosimetry and real-time monitoring of anatomy. Motion of anatomy and changes in target volume during treatment are becoming

more widely recognised as a major source of uncertainty during radiotherapy.

Fig 1: Screen shot of visualisation software. The reconstructed prostate volume from the TRUS probe is co-registered with the reconstructed dwell positions from the BrachyView probe. The planned locations determined by the CT and TPS dataset are also displayed.

BRACHYTHERAPY | Congress report

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