ESTRO 2023 - Abstract Book

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ESTRO 2023

AcurosBV seemingly improves dose calculation for distances relevant in brachytherapy. For the PTVs a consistent increased dose is reported when using TG43, which is important when PTV coverage is considered. For head-and-neck and lungs, the TG43 calculated dose to adjacent serial organs and healthy lung tissue is also higher, which can in both cases potentially inhibit adequate target coverage. The findings of this work highlight that further work is required to correlate dose prescriptions to PTVs and dose limits to OARs, based on more accurate dose values achieved by recent model-based dose calculation algorithms.

PO-2171 Dose estimation of workers in electronic brachytherapy rooms for superficial and breast treatments

A. Gonzalez Rodriguez 1 , R. Castro Moreno 1 , S.A. Lozares Cordero 1 , A. Gandía Martinez 1

1 University Hospital Miguel Servet, Medical Physics and Radiological Protection, Zaragoza, Spain

Purpose or Objective The goal of this study is to establish a practical criterion to optimize the use of radiological protection materials in electronic brachytherapy. Materials and Methods Skin and breast treatments were replicated using the Axxent ® device (Xoft Inc.) and different treatments applicators: a conical applicator with a 50 mm diameter for skin treatments and a 30 cc volume “balloon” for breast treatments. To simulate the patient attenuation, we used RW3 solid water rounding the balloon or in contact to the conical applicator. Environmental dose rate measurements were taken at different points in a treatment room reproducing real conditions of superficial and breast treatments, with and without different types of radiological protections. Measurements were taken without any radiological protection in the points of the Figure 1 and with different combinations of radiological protection materials: a 2 mm of Pb equivalent attenuation screen, a 0.25 mm Pb equivalent leaded apron and, in breast treatments, a 0.5 mm of Pb equivalent leaded blanket. With these measurements, absorbed doses were calculated over a year with an 8 patient per day or 40 per week approximation. Measurements below 0.5 µ Sv/h were considered background radiation. Results are compared with the The maximum number of patients that could be treated without exceeding the dose limits was estimated with a dose limit of 6mSv/year, 3/10 of the annual IAEA recommended dose limits [1]. Results • Radiological protective screen showed more radiation attenuation than using an apron or a blanket (see Figure 2). • The measurement points were 13 in different treatment room locations (see Figure 1). Nevertheless, employees frequently work at 0.5 m (P1), 1 m (P2) and 1.5 m (P3) from the patient, where environmental dose rate measurements are higher (see Figure 2).