ESTRO 2024 - Abstract Book

S4884

Physics - Quality assurance and auditing

ESTRO 2024

Conclusion:

The bigger spread of results for electron beams compared to Co-60 and photon beams may be attributed to participating institutions not being familiar or less experienced with the dosimetry protocol for electron beams. Although participating centres reported following the IAEA TRS 398, it is more challenging to implement the protocol as calibration of electron beam protocols involve more steps than for photon beams and include a conversion of ionization to dose. The variation in SD between higher at lower energy electron beams may be attributed to different sources of uncertainties with lower energies suffering from higher positional uncertainty and dosimetry equipment selection because of the steeper dose gradients while for higher energies there may be errors related to the conversion from the ionization curve to dose curve and determination of z ref . Treatment with electrons is not commonly practiced in some centres particularly in low- and middle-income countries. It is also in these countries where the recognition of CQMPs and formal supervised clinical training is not implemented widely. In such scenarios, clinical training may leave some gaps, for example in electron dosimetry, which may not be addressed in the absence of a continuing professional development (CPD) program. Implementation of supervised clinical training and formal recognition of clinically qualified medical physicists and CPD requirements by Member States may mitigate the deficiencies in dosimetry practices observed in this analysis.

Keywords: Dosimetry, Audit, Electron

References:

1. Izewska J, Bokulic T, Kazantsev P, Wesolowska P, Van Der Merwe D (2020), 50 Years of the IAEA/WHO postal dose audit programme for radiotherapy: what can we learn from 13756 results? Acta Oncologica, 59:5, 495-502, doi: 10.1080/0284186X.2020.1723162. 2. Dimitriadis A, Kazantsev P, Chelminski K, Titovich E, Naida E, Magnus T, Meghzifene A, Azangwe G, Carrara M, Swamidas J (2023) IAEA/WHO postal dosimetry audit methodology for electron beams using radio photoluminescent dosimeters. Medical Physics, doi: 10.1002/mp.16776

3. International Atomic Energy Agency (2006), Absorbed Dose Determination in External Beam Radiotherapy: An International Code of Practice for Dosimetry Based on Standards of Absorbed Dose to Water, TRS 398. IAEA, Vienna

2404

Mini-Oral

Proton therapy robustness in a pilot study prior to a randomised trial for high-risk prostate cancer

Sofie Tilbæk 1,2 , Stine Elleberg Petersen 1 , Liliana Stolarczyk 1 , Anne Vestergaard 1 , Heidi S. Rønde 1 , Lise Nørgaard Bentzen 3 , Jimmi Søndergaard 4 , Morten Høyer 1,2 , Ludvig Paul Muren 1,2