S1625
Physics - Detectors, dose measurement and phantoms
ESTRO 2026
Diana Andrés, Raúl Pascual, Iago Mosquera, Constantino Fernández, César Quilis, Cristina Camacho Radiophysics and Radiation Protection, Hospital Clínico Universitario de Valencia, Valencia, Spain Purpose/Objective: The LIAC HWL accelerator (Sordina IORT Technologies) generates high dose per pulse electron beams used in intraoperative radiotherapy.It is supplied with SW Dose View software, which uses MC simulations to generate the relative dosimetry of the beams [1]. The aim of the study is to experimentally validate the model provided. Material/Methods: The cross-sectional profiles at the maximum depth for each energy, the depth-dose profiles (PDD) and output factors (OF) for the available applicators (diameters from 3 to 10 cm, and bevel angles of 0°, 15°, 30° and 45°) were measured and compared with the model for energies of 6, 8, 10 and 12 MeV. The comparison was not performed for 9 cm applicators as Sordina does not provide their data.Measurements were performed on the MP3XS water phantom with the microDiamond detectorThe parameters R100, R50, field sizes, penumbra, symmetry and flatness were evaluated. A gamma analysis was performed between the measured and modelled curves, with a tolerance of 1%-1mm. For the OFs, the 10 cm applicator with a 0° bevel was considered as the reference field. Results: Good agreement is observed between the measurements and the MC model:- The profiles are comparable within 1% in terms of symmetry and flatness, in all combinations of energy, diameter and bevel.- The measured profiles have greater penumbra and field size than the modelled ones, with differences of less than 1 mm.- The differences in R100 and R50 are less than 1 mm, being 2 mm in only one case (45° bevel, 3 cm diameter and 12 MeV), which is within the tolerances given by Sordina.- The gamma comparison between curves results in a 90.7% pass rate. Points with gamma > 1 correspond to the area beyond the penumbra of the profiles, mainly at the tails of the curves, and to the first millimetres of the PDDs, since the MC model does not start at a depth of 0 mm. An example is shown in Figure 1.
combination diameter = 4 cm, E = 12 MeV in all bevels, for which the differences reach 8.5% (Table 1).
Conclusion: This study has verified that the MC model provided is consistent with the dose distributions generated by our LIAC. It is a useful tool for its implementation and clinical use. However, it is recommended that some parameters, such as OFs, surface doses and off-field doses, be characterised experimentally. References: [1] Iaccarino, G., Strigari, L., D'Andrea, M., Bellesi, L., Felici, G., Ciccotelli, A., ... & Soriani, A. (2011). Monte Carlo simulation of electron beams generated by a 12 MeV dedicated mobile IORT accelerator. Physics in Medicine & Biology, 56(14), 4579. Keywords: intraoperative radiotherapy, Monte Carlo models Digital Poster 237 Micro-dosimetry in proton-beam radiation therapy treatment Sree Bash Chandra Debnath 1 , Didier Tonneau 2 , Carole Fauquet 2 , Robert Schäfer 3 , David Meer 3 , Sairos Safai 3 1 Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernadin Cancer Center, Loyola University Chicago, Maywood, USA. 2 CINaM UMR 7325, Aix-Marseille University, Marseille, France. 3 Dosimetry and Imaging- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland Purpose/Objective: Scintillating dosimetry has become the most promising technique in modern radiation therapy due to its precise and accurate dose measurement capabilities [1-3]. However, its suitability for precise proton mini-beam dosimetry and treatment is still being evaluated. Therefore, this study is focused on developing a new generation scintillating detection technique, and its performance evaluation and feasibility test under high-energy proton beams. Material/Methods: A new inorganic scintillating detection (ISD) system has been developed and calibrated under laboratory conditions for radiation dose measurement. The micrometric sensitive scintillating volume of the detection system was defined through precise
- The OFs are comparable within 2%, except for the
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