Monte Carlo dose calculation for radiotherapy treatment planning: Dose to water or dose to medium?

Abstract

The Monte Carlo method enables accurate dose calculation for radiotherapy treatment planning and has been implemented in some commercial treatment planning systems. Unlike conventional dose calculation algorithms that provide patient dose information in terms of dose to water the Monte Carlo method calculates the energy deposition in different media and expresses dose to medium. This paper discusses the differences in dose calculated using water with different electron densities and that calculated for different biological media and the clinical issues in reporting dose using dose to water and dose to medium. A recommendation is made based on our studies to report dose in medium for radiotherapy treatment plan evaluation and for radiotherapy treatment outcome analysis. © 2009 Springer-Verlag.