電子線治療計画における吸収線量等価厚(AET)法とペンシルビーム法

抄録

The purpose of this study is to determine calculation accuracies of inhomogeneity correction using the absorption equivalent thickness (AET) method and the pencil beam method for electron dose distribution computations. l) In the AET method. AET factors are used to correct doses for tissue heterogeneties. In our experiment. they were well fitted to the values in the following way, AET=1.2 〓 (for lung tissue) AET=p〓 (for bone or soft tissue) where p 〓 Is the electron density of the tissue. The calculation error of the AET method in a lung tissue equivalent medium, cork, was more than 15% for electron energy of less than 10 MeV and/or small fields, since this method is not capable of taking into account the changes of electrons scattered from the other parts. 2) In the pencil beam method, computating results agreed well with the experimental ones within a maximum error of 10% for every energy range and every field.