Author Of 1 Presentation
MOUSE ABDOMEN RADIATION USING A 50 MEV PROTON BEAM: FLASH VS. CONVENTIONAL DOSE RATE
Abstract
Background and Aims
The normal tissue toxicity sparing and survival benefits of ultra-high dose rate radiation (FLASH) remain poorly understood. We present preliminary results of mouse abdomen FLASH proton radiation from a low-energy proton system (50 MeV) optimized for small animal radiobiological research.
Methods
We radiated 6-7 week old female C57BL/6 mice with partial abdomen radiation using the plateau region of a continuous (unpulsed) cyclotron-generated 50 MeV preclinical proton beam, transmitting through the abdomen, with 1.5cm width of beam via customized vertical and horizontal collimators. Mice were stratified into 3 groups: 1) control/sham radiation (n=8); 2) conventional dose rate (20Gy at ~1Gy/sec, n=19); and 3) FLASH (20Gy at 48-93Gy/sec, n=22). Mice were observed for survival. Colon tissue was harvested at 1-hour post-radiation. H&E and immunohistochemistry was performed for: yH2aX and cleaved caspase-3. Experiments were repeated in triplicate.
Results
Survival was different between FLASH and conventional groups: FLASH (13 days post radiation, 36.4% survival); conventional (15.6% survival, P = 0.04 ) [Figure 1]. One-hour post radiation, lower cleaved caspase-3 IHC staining was seen in the FLASH group versus conventional group, while yH2aX staining was similar in both groups [Figure 2].
Conclusions
Preliminary results of mouse partial abdomen FLASH proton radiation from a 50 MeV beam suggest FLASH proton radiation leads to better survival than conventional dose rate radiation. More studies are ongoing.