Calculations based on the track theory of biological cells agree with measuredinactivation cross sections for V-79 Chinese hamster cells bombarded with very heavyions in the track width regime where thindown
a reduction in cross section with an in-crease in the LET of the bombarding particles
is displayed. The calculation uses cellu-lar radiosensitivity parameters evaluated earlier from the data of survival curves and anew numerical calculation of the radial distribution of dose from δ-rays.These resultsrepresent a significant improvement over an earlier calculation of the same endpoint
where a formulation of the radial dose distribution which neglected the angular distribu-tion of ejected δ rays was used.