Eleni Kanouta (Denmark)
Aarhus University Hospital Danish Centre for Particle TherapyAuthor Of 1 Presentation
THE EFFECT OF PBS PROTON FLASH ON ACUTE SKIN TOXICITY AND TUMOR CONTROL IN A MOUSE MODEL
Abstract
Background and Aims
The aim of this study was to test the effect of proton FLASH delivered with a pencil beam scanning (PBS).
Methods
The right hind limb of CDF1 mice were irradiated in a single fraction in the entrance plateau of a scanning proton pencil beam using either conventional dose rate (0.4 Gy/s field dose rate, 244 MeV) or FLASH (69.7-88.7 Gy/s field dose rate, 250 MeV). The study included 292 non-tumor bearing mice and 80 mice with a C3H mouse mammary carcinoma implanted in the foot. The mice were irradiated with doses of 26-40Gy (non-tumor, conventional), 40-60Gy (non-tumor, FLASH) or 45-67Gy (tumor). The endpoints were the level of acute moist desquamation to the skin of the foot within 25 days post irradiation, and tumor control.
Results
Full dose response curves for acute damage to skin for both conventional and FLASH dose rate demonstrated a distinct normal tissue sparing effect in the FLASH arm of the study, with a mean value for the tissue sparing factor of 1.46. For tumor control, the pre-liminary dose response curves shows no difference between conventional and FLASH dose rates (follow up on tumor control is ongoing).
Conclusions
This study demonstrates a normal tissue sparing effect of proton FLASH delivered with pencil beam scanning, while no differences was found in tumor control rates. Compared to conventional dose rate, 41-55% higher dose were required to give the same biological toxicity in the normal tissue when using FLASH dose rates.