Conversion between different forms of LET

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 LETas measured in the detector medium (e.g. LET(200)CR-39 or LET(infinity)Si) to LET in water (LET(infinity)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 Ito 54 over an energy interval ranging from 0.8 to 2000 MeV/amu. For conversion of LET(200)CR-39 to LET(infinity) H(2)O in units of keV/mu m, a fitted function of Log(LET(infinity)H(2)O) = 0.1689 + 0.984Log(LET(200)CR-39) was obtained. For conversion of LET(infinity)Si to LET(infinity)H(2)O, a fitted function of Log(LET(infinity)H(2)O) = -0.2902 + 1.025Log(LET(infinity)Si) was obtained. (C) 2010 Elsevier Ltd. All rights reserved.