ESTRO 2025 - Abstract Book

S2610

Physics - Detectors, dose measurement and phantoms

ESTRO 2025

scale phantom. Efforts will include enhancing lung realism and designing an MR-compatible motion system to create a versatile phantom suitable for theranostic procedures, including novel technologies as MRI-guided radiotherapy.

Keywords: lung, 4D-CT, MRI

References: [1] Pallotta, S. et al. "ADAM: a breathing phantom for lung SBRT quality assurance." Physica Medica 49 (2018): 147-155. [2] Campos, A. et al "The role of computed tomography for the evaluation of lung disease in alpha-1 antitrypsin deficiency." Chest 153.5 (2018): 1240-1248. [3] Dietrich, O. et al. "T1 relaxation time constants, influence of oxygen, and the oxygen transfer function of the human lung at 1.5 T—A meta-analysis." European journal of radiology 86 (2017): 252-260. [4] Ratto, F. et al. " Sponges based on polydimethylsiloxane as pulmonary phantom for diffuse optics ." Proceeding under review [5] Pallotta, S. et al. "ADAM phantom to test 4D medical imaging and dose delivery devices." Physics in Medicine & Biology 64.10 (2019):105002.

2695

Digital Poster Assessing Micro Silica Bead Thermoluminescent Dosimeters for Out-of-Field Dose Verification for Cardiac Devices in Radiotherapy SHAKARDOKHT JAFARI 1 , Ryan Howarth 2 , Sarah Muscat 1 , Antony L. Palmer 1,2 1 Radiotherapy Physics, Portsmouth Hospitals University NHS Trust, Portsmouth, United Kingdom. 2 School of Mathematics and Physics, University of Portsmouth, Portsmouth, United Kingdom Purpose/Objective: To assess the accuracy of micro silica bead thermoluminescent dosimeters (TLDs) for verifying radiotherapy treatment planning system (TPS) out-of-field dose calculations relevant to Cardiac Implantable Electronic Devices (CIEDs), which are susceptible to radiation-induced malfunctions. Material/Methods: The use of bead dosimeters was validated in phase 1 with arrays of 19 beads placed within the PTV in-field, across multiple techniques including VMAT and SABR. Plans were created in Pinnacle3 (Philips), covering various degrees of complexity, including very high and low dose levels (0.4 to 15 Gy), delivered on a Varian Truebeam. The measured doses were compared to TPS predictions. In phase 2, 16 cm arrays of beads transitioned from in-field to out-of-field regions to simulate CIED placement, and the results were compared with both TPS predictions and radiochromic film (EBT3) measurements using triple channel technique in FilmQAPro software (See fig.1).