Results of an independent dosimetry audit for scanned proton beam therapy facilities

Antonio Carlino*, Hugo Palmans, Clare Gouldstone, Petra Trnkova, Ole Noerrevang, Anne Vestergaard, Gloria Vilches Freixas, Geert Bosmans, Stefano Lorentini, Marco Schwarz, Benjamin Koska, Jörg Wulff, Stanislav Vatnitsky, Markus Stock

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)

Abstract

Purpose: An independent dosimetry audit based on end-to-end testing of the entire chain of radiation therapy delivery is highly recommended to ensure consistent treatments among proton therapy centers. This study presents an auditing methodology developed by the MedAustron Ion Beam Therapy Center (Austria) in collaboration with the National Physical Laboratory (UK) and audit results for five scanned proton beam therapy facilities in Europe. Methods: The audit procedure used a homogeneous and an anthropomorphic head phantom. The phantoms were loaded either with an ionization chamber or with alanine pellets and radiochromic films. Homogeneously planned doses of 10 Gy were delivered to a box-like target volume in the homogeneous phantom and to two clinical scenarios with increasing complexity in the head phantom. Results: For all tests the mean of the local differences of the absolute dose to water determined with the alanine pellets compared to the predicted dose from the treatment planning system installed at the audited institution was determined. The mean value taken over all tests performed was −0.1 ± 1.0%. The measurements carried out with the ionization chamber were consistent with the dose determined by the alanine pellets with a mean deviation of −0.5 ± 0.6%. Conclusion: The developed dosimetry audit method was successfully applied at five proton centers including various “turn-key” Cyclotron solutions by IBA, Varian and Mevion. This independent audit with extension to other tumour sites and use of the correspondent anthropomorphic phantoms may be proposed as part of a credentialing procedure for future clinical trials in proton beam therapy.

Original languageEnglish
Pages (from-to)145-153
Number of pages9
JournalZeitschrift fur Medizinische Physik
Volume31
Issue number2
DOIs
Publication statusPublished - May 2021

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