Transformative Technology for FLASH Radiation Therapy
R. Schulte, Carol Johnstone, S. Boucher, E. Esarey, C. G. R. Geddes, Maksim Kravchenko, Sergey Kutsaev, Billy W. Loo, François Méot, B. Mustapha, Kei Nakamura, Emilio A. Nanni, Lieselotte Obst-Huebl, S. Sampayan, C. B. Schroeder, Ke Sheng, Antoine M. Snijders, Emma Snively, Sami Tantawi, J. van Tilborg
Abstract
The general concept of radiation therapy used in conventional cancer treatment is to increase the therapeutic index by creating a physical dose differential between tumors and normal tissues through precision dose targeting, image guidance, and radiation beams that deliver a radiation dose with high conformality, e.g., protons and ions. However, the treatment and cure are still limited by normal tissue radiation toxicity, with the corresponding side effects. A fundamentally different paradigm for increasing the therapeutic index of radiation therapy has emerged recently, supported by preclinical research, and based on the FLASH radiation effect. FLASH radiation therapy (FLASH-RT) is an ultra-high-dose-rate delivery of a therapeutic radiation dose within a fraction of a second. Experimental studies have shown that normal tissues seem to be universally spared at these high dose rates, whereas tumors are not. While dose delivery conditions to achieve a FLASH effect are not yet fully characterized, it is currently estimated that doses delivered in less than 200 ms produce normal-tissue-sparing effects, yet effectively kill tumor cells. Despite a great opportunity, there are many technical challenges for the accelerator community to create the required dose rates with novel compact accelerators to ensure the safe delivery of FLASH radiation beams.