Modeling for predicting survival fraction of cells after ultra-high dose rate irradiation.

FLASH radiotherapy (FLASH-RT) with ultra-high dose rate (UHDR) irradiation (i.e., > 40 Gy/s) spares the function of normal tissues while preserving antitumor efficacy, known as the FLASH effect. The biological effects after conventional dose rate-radiotherapy (CONV-RT) with ≤ 0.1 Gy/s have been well modeled by considering microdosimetry and DNA repair processes, meanwhile modeling of radiosensitivities under UHDR irradiation is insufficient. Here, we developed an integrated microdosimetric-kinetic (IMK) model for UHDR irradiation enabling the prediction of surviving fraction after UHDR irradiation. The IMK model for UHDR-irradiation considers the initial DNA damage yields by the modification of indirect effects under UHDR compared to CONV dose rate. The developed model is based on the linear-quadratic (LQ) nature with the dose and dose square coefficients, considering the reduction of DNA damage yields as a function of dose rate. The estimate by the developed model could successfully reproduce the in vitro experimental dose-response curve for various cell line types and dose rates. The developed model would be useful for predicting the biological effects under the UHDR irradiation.

Informations de copyright

© 2023 Institute of Physics and Engineering in Medicine.