Microdosimetry and Katz's track structure theory. I. One-hit detectors

A microdosimetric treatment of the response of one-hit detectors to radiation is formulated and compared with the model proposed by R. Katz, S. C. Sharma, and M. Homayoonfar (in Topics in Radiation Dosimetry, Suppl. I (F. H. Attix, Ed.), pp. 317-383, Academic Press, New York, 1972) within the framework of their track-structure theory. It is shown that radial dose distributions (on which the track structure theory is based) are generally poor substitutes for the exact microdosimetric distributions except when (a) the target is much larger than the radial extent of the track or (b) the "effective" specific energy in the target (alpha z, see text) is negligibly small. Since neither one of these conditions is generally satisfied, it is suggested that a meaningful search for one-hit detectors be based on a microdosimetric description of the stochastics of energy deposition. An analysis of the phi x-174 bacteriophage inactivation data is presented.