Analysis and evaluation of planned and delivered dose distributions: practical concerns with γ- and χ- Evaluations

Abstract

One component of clinical treatment validation, for example in the commissioning of new radiotherapy techniques or in patient specific quality assurance, is the evaluation and verification of planned and delivered dose distributions. Gamma and related tests (such as the chi evaluation) have become standard clinical tools for such work. Both functions provide quantitative comparisons between dose distributions, combining dose difference and distance to agreement criteria. However, there are some practical considerations in their utilization that can compromise the integrity of the tests, and these are occasionally overlooked especially when the tests are too readily adopted from commercial software. In this paper we review the evaluation tools and describe some practical concerns. The intent is to provide users with some guidance so that their use of these evaluations will provide valid rapid analysis and visualization of the agreement between planned and delivered dose distributions.