Calculating the Medium Correction Factor for the PTW-30013 Ionization Chamber

摘要

In this paper, the medium correction factor for lung, muscle, blood and bone was calculated using analytical method and MCNP simulation for different beam qualities. To validate the calculation method, the medium correction factor of the PTW-30013 ionization chamber for air was specified by measuring the air kerma and the absorbed dose to water calibration coefficients in the standard radiation field of 60Co in Secondary Standards Dosimetry Laboratory (SSDL) of Iran. The value of the medium correction factor for muscle and blood was gotten close to one because of their close density and atomic composition to water. For lung, the medium correction factor was calculated more over 1.08 for different beam qualities. Also, this factor for the bone was determined less than 0.98. The results of this study revealed that for accurate measurement of absorbed dose in low (e.g., lung) or high (e.g., bone) density materials, by ionization chambers calibrated in term of absorbed dose to water, the medium correction factor has to be considered.