ESTRO 2025 - Abstract Book

S2682

Physics - Detectors, dose measurement and phantoms

ESTRO 2025

Conclusion This RLI-based methodology, combined with Abel transform inversion, demonstrates potential as a tool for 3D dosimetry of cylindrical electron beams. This method could be applied to both conventional and FLASH condition. Although the current approach assumes cylindrical symmetry, extending the system to incorporate additional viewing angles could enable reconstruction of more complex dose distributions.

Keywords: FLASH, Scintillation, Dose reconstruction

References 1 - Ashraf, M.Ramish & Rahman, Mahbubur & Williams, Benjamin & Gladstone, David & Pogue, Brian & Bruza, Petr. (2020). Dosimetry for FLASH Radiotherapy: A Review of Tools and the Role of Radioluminescence and Cherenkov Emission. 2 - Ashraf, M.R., Rahman, M., Zhang, R., Cao, X., Williams, B.B., Hoopes, P.J., Gladstone, D.J., Pogue, B.W. and Bruza, P. (2021), Technical Note: Single-pulse beam characterization for FLASH-RT using optical imaging in a water tank. Med. Phys., 48: 2673-2681. 3 - Goulet, M., Rilling, M., Gingras, L., Beddar, S., Beaulieu, L. and Archambault, L. (2014), Novel, full 3D scintillation dosimetry using a static plenoptic camera. Med. Phys., 41: 082101.

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Digital Poster Characterisation of glass bead TLDs for clinical proton beam dosimetry Alexa Wong 1 , Maia Grady 1 , Andrew Nisbet 1 , Shakardokht Jafari 2,3

1 Medical Physics & Biomedical Engineering, University College London, London, United Kingdom. 2 Founder, Trueinvivo, Portsmouth, United Kingdom. 3 Medical Dosimetry, NHS Trust, Portsmouth, United Kingdom

Purpose/Objective This study aims to assess the feasibility of using commercial glass beads as novel thermoluminescence dosimeters (TLDs) for high-energy clinical proton radiotherapy dosimetry. Material/Methods Five types of glass beads (A, B, C, D, E) were irradiated using a Varian ProBeam® proton therapy unit at University College London Hospital. Type A beads (1.65 x 1.15 mm) were manufactured by TOHO; Type B (1.50 x 1.00 mm) and C (0.95 x 1.00 mm) were manufactured by stretching and grinding into desired heights; Type D (1.50 x 1.00 mm) and E (1.00 x 1.00 mm) were shaped using a laser. Dose linearity and energy dependence were investigated from 27 cGy to 5.18 Gy, and 80 MeV to 240 MeV respectively. The measurements were compared to a Markus parallel plate ionisation chamber. Depth-dose profile measurements were also conducted for separate distributions: pristine Bragg Peak (70 MeV beam) and Spread-Out Bragg Peak (SOBP). For these measurements, beads were sewn onto a laminated sheet designed in AutoCAD for high precision and submerged in a water phantom (Figure 1c, d).