Radiation response of primary human skin fibroblasts and their bystander cells after exposure to counted particles at low and high LET.

Purpose: To investigate the dependence of bystander effects on linear energy transfer (LET) in the low dose region.

Materials And Methods: The single-ion microbeam of the Physikalisch-Technische Bundesanstalt (PTB) was used to irradiate confluent primary human skin fibroblasts. Cells plated on a special irradiation dish were targeted with 10 MeV protons (LET 4.