Antonio Carlino1, Hugo Palmans2, Clare Gouldstone3, Petra Trnkova4, Ole Noerrevang5, Anne Vestergaard5, Gloria Vilches Freixas6, Geert Bosmans6, Stefano Lorentini7, Marco Schwarz8, Benjamin Koska9, Jörg Wulff9, Stanislav Vatnitsky10, Markus Stock10. 1. MedAustron Ion Therapy Center, Medical Physics, Wiener Neustadt, Austria. Electronic address: antonio.carlino@medaustron.at. 2. MedAustron Ion Therapy Center, Medical Physics, Wiener Neustadt, Austria; National Physical Laboratory, Teddington, United Kingdom. 3. National Physical Laboratory, Teddington, United Kingdom. 4. HollandPTC, Huismansingel 4, Delft, The Netherlands; Erasmus MC, Department of Radiation Oncology, Rotterdam, The Netherlands. 5. Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark. 6. Maastro Proton Therapy, Department of Radiation Oncology, GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands. 7. Centro di Protonterapia, APSS, Via al Desert 14, 38122 Trento, Italy. 8. Centro di Protonterapia, APSS, Via al Desert 14, 38122 Trento, Italy; TIFPA-INFN, Trento, Italy. 9. West German Proton Therapy Centre Essen, Hufelandstr. 55, Essen, Germany; University Hospital Essen, Hufelandstr. 55, Essen, Germany. 10. MedAustron Ion Therapy Center, Medical Physics, Wiener Neustadt, Austria.
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 10Gy 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.
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 10Gy 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.
Authors: Paige A Taylor; Jessica Lowenstein; David Followill; Stephen F Kry Journal: Int J Radiat Oncol Biol Phys Date: 2021-11-13 Impact factor: 7.038