Feasibility of Laser-Driven Protons for FLASH Radiotherapy to Treat Cancerous Tumors*

External beam radiation therapy (RT) using x-rays is a common method of cancer treatment, although the dose distribution of radiation throughout the body, including normal tissue, makes it an inefficient and imprecise technique with costly side effects. In proton RT, most of the energy is deposited at a targeted depth (the Bragg Peak). Compared to x-ray RT, this unique property decreases dosage to non-target tissues by at least a factor of two[1]. Current proton accelerators pose many disadvantages prohibiting them from common usage, such as the cost being over $100 million[2], and the size, which is unrealistic for installation in most facilities. Laser driven proton RT is a promising method with reasonable size and reduced cost. In addition, lasers produce protons of many energies, offering the possibility of treating multiple depths with one beam. We discuss the pros and cons of laser driven protons in the context of future high power lasers and suggest ways to efficiently apply these lasers to conventional and FLASH RT, where high dose in a short time has shown promise as an even more efficient way of treating cancer. 

1.  U. Schneider, A. Lomax, & N. Lombriser, “Comparative risk assessment of secondary cancer incidence after treatment of Hodgkin's disease with photon and proton radiation.” Radiation research, 154(4), 382–388 (2000)

2. C.-M. Ma, et al., “Development of a Laser-Driven Proton Accelerator for Cancer Therapy.” Laser Physics, 16(4), 639-646 (2006)