Biological effectiveness of high-LET radiations in normal human cells

Abstract

It has been widely accepted that high-LET radiations effectively kill cells, thereby having been clinically applied to cancer radiotherapy. Normal cells, however, coexist not in cancerous tissue but also in the periphery of the targeting region of radiation treatment. We here therefore investigated the cell-killing effect of six kinds of high-LET radiations in confluent, density-inhibited, normal human diploid fibroblasts. Ion-beam irradiation was performed at TIARA in JAERI-Takasaki. RBE values, relative to the dose of γ-rays (0.2 keV/μm) giving 10 % survival, for ⁴He²⁺ (16 keV/μm), ¹²C⁶⁺ (76 keV/μm), ¹²C⁵⁺ (108 keV/μm), ²⁰Ne⁸⁺ (321 keV/μm), ²⁰Ne⁷⁺ (437 keV/μm), ⁴⁰Ar¹³⁺ (1610 keV/μm), were 1.4, 3.0, 3.9, 3.4, 2.7, 0.8, respectively. Results of the experiments to evaluate the late-arising effect in the progeny of cells surviving heavy ions, and bystander effect, will also be shown.