F-value as a Chromosomal Fingerprint of the Quality of Radiation

Abstract

Since the first proposal by Brenner and Sachs (Radiation Res. 140, 134–142, 1994), the F-value, the ratio of inter- to intra-chromosomal interchanges, as a biomarker for the quality of radiation has been a matter of repeated discussion. Controversies seem to stem from the selection of data which are heterogeneous in terms of chromosome scoring criteria and dose range. In the context of the critical evaluation of the validity of the F-value, the cytogenetic data obtained in our laboratory from the in vitro irradiation of human peripheral blood lymphocytes have been re-assessed for the F-value. The results were consistent with the original contention that the densely ionizing radiations showed lower F-value. The differential F-value was more pronounced in the low-dose range and disappeared with the increase of the dose, or more precisely with the number of charged particles passing through the cell nucleus. The range of charged particles also plays a role, which makes the F-value of neutrons insensitive to their energy due to a wide variation of the kinetic energy of recoil protons.