FLASH Pre Clinical Dosimetry

Recent radiation studies with ultra-high dose rates, UHDR, (\>40 Gy/s), known as FLASH radiotherapy (RT), have demonstrated a remarkable reduction in normal tissue toxicity (known as the "FLASH effect") with respect to conventional dose-rate radiotherapy (few Gy/min) while maintaining similar tumour response. This could represent a step-change in cancer treatment with significant benefits for patients and healthcare providers. However, the mechanisms underpinning the FLASH effect are still unknown. Extensive pre-clinical radiation studies are necessary to gain the full understanding of this phenomenon and validate the approach for clinical trials.

Xstrahl has developed a pre-clinical FLASH radiotherapy system to enable leading cancer research teams to perform precise FLASH investigations. . Two UK centres (Institute of Cancer Research and Queens University Belfast) purchased our two first SARRP FLASH systems as part of the recent MRC grant (Investment in World Class Labs). It is now essential that we develop a methodology to carry out the accurate and traceable dosimetry and have suitable detectors to measure the radiation dose in the FLASH regime, which is delivered within milliseconds rather than minutes. No current off-the-shelf dosimeters are available to provide accurate dose measurements for pre-clinical photon FLASH RT, and the dosimetry standards for FLASH radiotherapy are still emerging. The cancer research teams need to know accurately the dose delivered to their samples for FLASH research to be valid and reproduced across the UK research groups and world-wide. This is also essential to avoid flawed interpretation of the pre-clinical studies, de-risking clinical trials and accelerate clinical adoption of FLASH treatments.

With the team of experts form the National Physical Laboratory, we have the opportunity to pioneer how pre-clinical or general FLASH dosimetry is defined world-wide across other measurement standard laboratories. That puts us, as a UK manufacturer, on the forefront of this technology. As the first manufacturer to develop and introduce on the market a pre-clinical photon FLASH system, the dosimetry system to be developed as part of this call will be the world's first. This will enable us to provide our solution to a wider research base and help accelerate the introduction of FLASH radiotherapy to clinical practice.