ESTRO 2023 - Abstract Book

S523

Sunday 14 May 2023

ESTRO 2023

There are considerable variations in clinical practice. A practice survey can be used to map practice, and may help practice improvement in some clinics. In 2021, BRAPHYQS (Physics working group of GEC-ESTRO) Working Package (WP) 22 decided to undertake two such global practice surveys: one aimed at physicists and one at physicians. This abstract describes the physicist survey results. Materials and Methods A physicist survey with 17 questions was created using Surveymonkey TM (Momentive Inc). The response options were specified using dropdown lists whenever possible, however each question had an “other” or “comment” response option to allow the responder to add free text information. The last few questions were open questions allowing text answers to map the responders thoughts on current, and future, clinical practice. Potential responders were contacted through the ESTRO newsletter, the MedPhys mailing list, national medical physics mailing lists and professional networks. The survey opened on March 1st 2022 and closed on July 31st 2022. Results 76 responses were received, of which 11 were excluded. Of the remaining 65, 25 were anonymous. 28 were from Europe, 3 from the African continent, 5 from Australia and New Zealand, 2 from the US. 26 clinics do not do any commissioning and acceptance testing, 26 clinics do this with an in-house built phantom. 35 clinics do not measure percentage depth doses (PDDs), 28 clinics measure PDDs with a range of detectors - however only 2 clinics use the measured PDDs for planning. 43 clinics do not measure any off-axis data. 49 clinics use the value from the calibration certificate in planning calculations. 41 clinics use an in-house spreadsheet for treatment planning. Those that use image-based planning use a variety of images for this. 2 clinics use radiobiological corrections to their treatment planning. In 9 of the clinics, no independent check on the calculation is carried out. 10 clinics would like to introduce image-based planning, and 22 would like to change otther aspects of their treatment process. The responders reported following a variety of guidelines. Conclusion Ruthenium plaque brachytherapy practice is starkly different from other radiation oncology practice in several ways. Pertinently, the majority of clinics do not measure PDDs or profiles on new plaques, and use spreadsheets for treatment planning. Surveyed staff expressed a range of desirable improvements to clinical practice. A transition to image-based planning is one of the most desirable changes named by responders, and this would likely improve tumour control. OC-0634 HDR-BT with 3D-printed individual applicators for skin BCC in the H&N area – initial results. A. Chyrek 1 , W. Burchardt 1,2 , G. Biel ę da 3,2 , A. Kluska 1 , A. Chiche ł 1 1 Greater Poland Cancer Centre, Brachytherapy Department, Pozna ń , Poland; 2 University of Medical Sciences, Electroradiology Department, Pozna ń , Poland; 3 Greater Poland Cancer Centre, Medical Physics Department, Pozna ń , Poland Purpose or Objective In 2020 after developing the process of preparing applicators in 3D printing technology, we started using this technique to treat skin cancers in anatomically difficult locations with high-dose-rate brachytherapy (HDR-BT). This retrospective study aims to evaluate the initial efficacy and toxicity of this method for skin basal cell carcinoma (BCC) located in challenging regions of the head & neck area. Materials and Methods Between 06.2020 and 03.2022 20 patients with 25 BCC tumors were treated. The exact process of making the applicator (Fig. 1) and planning the treatment was presented in our previous report. The response rate (RR) to the treatment and early toxicity was assessed four weeks after finishing HDR-BT, then patients were evaluated every 3-6 months for the late toxicity and local control (LC). References [1] Acta Oncologica, 59:8, 918-925, DOI: 10.1080/0284186X.2020.1762925 [2] Private communication, Eckert & Ziegler BEBIG, Germany