The Sparing Effect of Multibeam Ultra-High Dose-Rate Irradiation on Intestinal Tissue in Mice

Area of Science:

• Radiation oncology
• Preclinical research
• Radiobiology

Background:

• Ultra-high dose-rate (UHDR) irradiation, known as the FLASH effect, offers normal tissue sparing compared to conventional dose-rate (CDR) irradiation.
• Clinical application of UHDR is limited by the inability to achieve conformal doses due to the lack of gantry rotation during single-beam delivery.

Purpose of the Study:

• To investigate if the FLASH effect, a form of tissue sparing, is maintained when UHDR irradiation is delivered using multiple beams with short intervals.
• To assess the impact of multibeam UHDR irradiation on survival, body weight recovery, and intestinal crypt regeneration in a murine model.

Main Methods:

• Mice underwent whole-abdominal irradiation using either UHDR or CDR electron beams with dose rates of ≥550 Gy/s for UHDR.
• Multibeam regimens involved 1-minute intervals between beams, with varying total doses and beam numbers (e.g., 11 Gy in five beams, 8 Gy in two beams, 12 Gy in four beams).

Main Results:

• Multibeam UHDR irradiation significantly improved survival rates compared to CDR, particularly with an 11 Gy regimen in five beams.
• Better body weight recovery was observed with UHDR (8 Gy, two beams) versus CDR (8 Gy).
• Enhanced intestinal crypt regeneration was noted with UHDR (12 Gy, four beams) compared to CDR (12 Gy).

Conclusions:

• The intestinal FLASH effect is maintained in a murine model when UHDR irradiation is delivered in multiple beams.
• This finding supports the potential of multibeam UHDR irradiation as a viable strategy for clinical applications requiring conformal dose distributions and tissue sparing.