Measurements of the equivalent whole-body dose during radiation therapy bycytogenetic methods

Estimates of equivalent whole-body dose following partial body exposure can be performed using different biophysical models. Calculations should be co mpared with biodosimetry data, but measurements are complicated by mitotic selection induced in target cells after localized irradiation. In this pape r we measured chromosomal aberrations in peripheral blood lymphocytes durin g radiotherapy, and estimated the equivalent whole-body dose absorbed, by u sing the novel technique of interphase chromosome painting. Premature chrom osome condensation was induced in stimulated lymphocytes by incubation in c alyculin A, and slides were hybridized in situ with whole-chromosome DNA pr obes specific for human chromosomes 2 and 4. Reciprocal exchanges were used to estimate the equivalent whole-body dose, based on individual pre-treatm ent ill vitro calibration curves. Equivalent whole-body dose increased as a function of the number of fractions, and reached a plateau at high fractio n numbers. Chromosomal aberration yields were dependent on field size, tumo ur position and concurrent chemotherapy. Results suggest that interphase ch romosome painting is a simple technique able to give a reliable estimate of the equivalent whole-body dose absorbed during therapeutic partial-body ir radiation.