ESTRO 2022 - Abstract Book

S464

Abstract book

ESTRO 2022

M. De Brabandere 1

1 University Hospital Leuven, Dept. of Radiation Oncology, Leuven, Belgium

Abstract Text Ocular plaque brachytherapy is a treatment technique for uveal melanoma, offering equivalent tumor control to enucleation while preserving the eye. The most widely used ophthalmic applicators are the COMS type plaques with low energy photon I-125 sources and the beta-emitting Ru-106 plaques, the latter mainly in Europe. For COMS type plaques using I-125 seeds there are well established guidelines ensuring a level of uniformity in the treatment planning and quality management process. For Ru-106 plaque brachytherapy there are no standardized methods for source calibration, applicator commissioning and treatment planning. In this presentation we focus on Ru-106 plaques. Acceptance and quality control aspects are discussed in more detail: measurements of dose rate, dose uniformity and relative depth dose profiles are challenging due to the limited availability of commercial equipment and calibration services. Also treatment planning strategies for Ru-106 are limited as there is no certified TPS available on the market. Most centers perform a 1D calculation to obtain the treatment time for a given prescribed dose. Dose prescription, treatment time calculation, and dose rate aspects are discussed. L.S. Fog 1 , M. De Brabandere 2 , E. Placidi 3 , A. Slocker 4 , L. Tagliaferri 5 , Ȧ .C. Tedgren 6 , M. Andrássy 7 , C. Schulz 7 , E.C. Chimfwembe 8 , F. Siebert 9 1 Alfred Health Radiation Oncology / The Royal Victorian Eye and Ear Hospital, Radiation Oncology / Ocular Oncology, Melbourne, Australia; 2 University Hospital Leuven, Department of Radiation Oncology, Leuven, Belgium; 3 Policlinico Universitario Agostino Gemelli IRCCS, Medical Physics, Rome, Italy; 4 Catalan Institute of Oncology, Radiation Oncology, Barcelona, Spain; 5 Policlinico Universitario Agostino Gemelli IRCCS, Radiation Oncology, Rome, Italy; 6 Linköping University and Karolinska University hospital, Medical Radiation Physics and Nuclear Medicine, Linköping, Sweden; 7 Eckert and Ziegler BEBIG, ., Berlin, Germany; 8 ESTRO, ., Brussles, Belgium; 9 Christian-Albrechts-Universität , Department of Radiotherapy, Kiel, Germany Ocular melanoma may be treated with brachytherapy (BT) using Ru-106 or I-125, enucleation (removal of the globe), or external radiation therapy using photons or protons. Ru-106 is a beta emitter with a half life of 372 days and an effective treatment depth of up to about 5 mm. The radioactive Ru-106 eye plaque is sutured onto the tumour and removed once the prescribed dose has been delivered. Ru-106 BT is a niche treatment, delivered at only approximately 100 clinics globally. Prescription doses and planning methods vary considerably between clinics. In this work, we aim to create a comprehensive survey of Ru-106 BT practice. We hope that a detailed knowledge of clinical practice may help clinics deliver optimal practice. SP-0526 GEC-ESTRO survey on global Ru-106 eye plaque brachytherapy practice Abstract Text Purpose/Objective

Fig 1: Ru-106 Eye Applicators and a Ruthenium plaque treatment, curtesy of the manufacturer Eckert & Ziegler BEBIG

Material/Methods

A range of survey methods and formats were investigated.

Surveys on Ru-106 plaque practice were created with input from a group of physicists and clinicians in ESTRO BRAPHYQS. The survey was extensively vetted by members of, and outside, this group. Sample surveys were filled in.

Results

Surveymonkey was chosen as the survey method. Two surveys were created: one for physicians and one for physicists, since they would likely be filled in separately. Dropbox answers were used whenever possible, while also giving responders the opportunity to provide free text responses if they wish to include additional information.

The physician survey includes questions on number of patient treatment per year, plaque types available at their centre ,