ESTRO 2024 - Abstract Book

S3340

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

Keywords: Computed radiography, Total body irradiation

2450

Digital Poster

In vivo dosimetry in total electron skin therapy using GAFchromic film.

MªTrinitat García Hernández 1 , Juan J. Rovira Escutia 1 , Mª Aurora Vicedo González 1 , Amparo González Sanchís 1 , Domingo Planes Meseguer 1 , Rafael García Mollá 1 , Domingo Granero Cabañero 1 , Roberto Gómez Pardos 1 , José Bea Gilabert 1 , Begoña Bordería Navarro 1 , Patricia Cuesta Calatayud 1 , Maria Luisa Alcaraz Lozan 1 , Álvaro Fernández Bernal 1 , Miguel Ángel Beltrán Bonet 1 , Noelia Hidalgo Llopis 1 , Ignacio Méndez Carot 2 1 Consorcio Hospital General Universitario de Valencia, Medical Physics, Valencia, Spain. 2 Institute of Oncology Ljubljana, Medical Physics, Ljubljana, Slovenia

Purpose/Objective:

Total skin electron therapy (TSEI) is mainly used for the treatment of mycosis fungoides. Several techniques have been developed in order to achieve a homogeneous irradiation over the body surface. Implementation of these techniques requires extensive measurements conducted on standard phantoms. Many challenges are associated with the clinical administration of the technique, such as variations in patient anatomy, patient positioning, regions with pronounced concavity or obliquity, and difficult-to-access areas, among others. According to the EORTC recommendations, regions of the skin where there is a high degree of curvature should not receive a dose higher than 120% of the prescribed dose [1]. In this sense, it is necessary to perform in vivo dosimetry. In this poster, we present the results of in vivo dosimetry for seven patients, using GAFchromic EBT3 film.

Material/Methods:

The technique used for TSEI is the modified Standford approach, with optimization of the gantry angles used for the dual fields. It is performed at a VersaHD accelerator (Elekta, Stockholm) with 6 MeV high dose rate mode (HDRE) electrons. For seven patients, 2.5 cm x 3 cm film pieces were positioned at 14 different anatomical locations over the patient: forehead, between clavicles, above the navel, on the left forearm, left lateral trunk, left quadriceps, metatarsal right and left foot, nape, between the scapulae, lumbar, right triceps, back of the right hand and left femoral bicep. GAFChromic EBT3 (Ashland Inc., Bridgewater, NJ, USA) film pieces were used. The pieces were handled, scanned and calibrated following the protocol detailed by [2]. The flatbed scanner used was an Epson Expression 12000XL (Seiko Epson Corporation, Nagano, Japan). Doses were obtained with the radiochromic film dosimetry web application Radiochromic.com (Radiochromic SL, Benifaió, Spain).

Results: