ESTRO 2024 - Abstract Book

S5420

Radiobiology - Tumour biology

ESTRO 2024

Medulloblastoma cell lines with differing p53 and c-Myc status were irradiated in 24-well microplates in low cell numbers with several different doses and fractionation schemes (2, 4 and 8 fractions in four days with 5-6 different doses each). Each microplate represented one treatment condition . Subsequently each well was scored for 60 days whether recurrence occurred, i.e. the generation of a confluent cell monolayer, or if no regrowth could be observed. Using the LQ-model of radiation survival the alpha/beta-ratio of each cell line, representing the fractionation sensitivity, was determined

Results:

The findings suggest a significant influence of dosage and fractionation on treatment outcomes. Lower irradiation doses were correlated with increased recurrence rates, underscoring the necessity for precise dosage optimization. Alpha/beta ratios within the range of 9-19 Gy were identified, and intriguing observations were made regarding the persistence of p53 wild-type cells post-irradiation, raising considerations of cellular senescence.