Design and validation of a dosimetric comparison scheme tailored for ultra-high dose-rate electron beams to support multicenter FLASH preclinical studies. (October 2022)

• Record Type: Journal Article
• Authors: Jorge, Patrik Gonçalves; Melemenidis, Stavros; Grilj, Veljko; Buchillier, Thierry; Manjappa, Rakesh; Viswanathan, Vignesh; Gondré, Maude; Vozenin, Marie-Catherine; Germond, Jean-François; Bochud, François; Moeckli, Raphaël; Limoli, Charles; Skinner, Lawrie; No, Hyunsoo Joshua; Wu, Yufan Fred; Surucu, Murat; Yu, Amy S.; Lau, Brianna; Wang, Jinghui; Schüler, Emil; Bush, Karl; Graves, Edward E.; Maxim, Peter G.; Loo, Billy W.; Bailat, Claude
• Is Part Of: Radiotherapy and oncology. Volume 175(2022)
• Page Start: 203
• Page End: 209
• Publication Date: 2022-10
• Subjects: UHDR -- FLASH -- Dosimetry -- Intercomparison -- Passive dosimeters; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2022.08.023
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: We established and validated scheme for UHDR intercomparisons. We bring bring dosimetry consensus across participating institutions. The method was tested and validated with high-energy electron beams between two centers and three different devices with CONV and UHDR. The compatibility between the measured and expected doses show good agreement. A first step towards dosimetric consensus for FLASH-RT. Abstract: Background and purpose: We describe a multicenter cross validation of ultra-high dose rate (UHDR) (>= 40 Gy/s) irradiation in order to bring a dosimetric consensus in absorbed dose to water. UHDR refers to dose rates over 100–1000 times those of conventional clinical beams. UHDR irradiations have been a topic of intense investigation as they have been reported to induce the FLASH effect in which normal tissues exhibit reduced toxicity relative to conventional dose rates. The need to establish optimal beam parameters capable of achieving the in vivo FLASH effect has become paramount. It is therefore necessary to validate and replicate dosimetry across multiple sites conducting UHDR studies with distinct beam configurations and experimental set-ups. Materials and methods: Using a custom cuboid phantom with a cylindrical cavity (5 mm diameter by 10.4 mm length) designed to contain three type of dosimeters (thermoluminescent dosimeters (TLDs), alanine pellets, and Gafchromic films), irradiations were conducted at expected doses of 7.5 to 16 Gy delivered at UHDR or conventional dose rates using various electron beams at the Radiation Oncology Departments of the CHUV in Lausanne, Switzerland and Stanford University, CA. Results: Data obtained between replicate experiments for all dosimeters were in excellent agreement (±3%). In general, films and TLDs were in closer agreement with each other, while alanine provided the closest match between the expected and measured dose, with certain caveats related to absolute reference dose. Conclusion: In conclusion, successful cross-validation of different electron beams operating under different energies and configurations lays the foundation for establishing dosimetric consensus for UHDR irradiation studies, and, if widely implemented, decrease uncertainty between different sites investigating the mechanistic basis of the FLASH effect.