Conversion between different forms of LET

摘要

Measurement of linear energy transfer (LET) spectra by detectors such as CR-39 PNTD or Si diodes for purposes of determining dose and dose equivalent in tissue often requires the conversion of LET as measured in the detector medium (e.g. LET_(200)CR-39 or LET_∞Si) to LET in water (LET_∞H_2O). Traditionally this conversion is carried out by multiplying values of LET in the form measured by a single numerical constant. Here we present an alternative conversion method wherein the single constant is replaced by a mathematical function obtained from a least squares fit of LET values for heavy ions of Z ranging from 1 to 54 over an energy interval ranging from 0.8 to 2000 MeV/amu. For conversion of LET _(200)CR-39 to LET_∞H_2O in units of keV/μm, a fitted function of Log(LET_∞H_2O) = 0.1689 + 0.984Log(LET_(200)CR-39) was obtained. For conversion of LET_∞Si to LET_∞H_2O, a fitted function of Log(LET_∞H_2O) = -0.2902 + 1.025Log(LET_∞Si) was obtained.