Electron Scattering in Conventional Cell Flask Experiments and Dose Distribution Dependency

Electron beam therapy (EBT) is commonly used for treating superficial and subdermal tumors. Previous cellular radiosensitivity research using EBT may be underestimating the contribution from flask wall scattering and the corresponding dose distribution. Single cell suspensions of Chinese hamster ovary (CHO) cells were plated on flasks and irradiated with 3, 4, 7, 9, and 18 MeV energy electron beams from two different institutions, and the spatial locations of surviving colonies were recorded. Gafchromic film dosimetry and Monte Carlo simulations were carried out to determine the spatial electron scattering contribution from the flask walls. Low electron irradiation resulted in an uneven surviving colony distribution concentrated near the periphery of the flasks, while spatial colony formation was statistically uniform at energies above 7 MeV. Our data demonstrates that without proper dosimetric corrections, studies using low energy electrons can lead to misinterpretations of energy dependent cellular radiosensitivity in culture vessels, and radiotherapeutic applications.