Conversion between different forms of LET

Abstract

Abstract 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 2 O). 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 2 O in units of keV/μm, a fitted function of Log(LET ∞ H 2 O) = 0.1689 + 0.984Log(LET 200 CR-39) was obtained. For conversion of LET ∞ Si to LET ∞ H 2 O, a fitted function of Log(LET ∞ H 2 O) = −0.2902 + 1.025Log(LET ∞ Si) was obtained.