A quality index for equivalent uniform dose

Abstract

Equivalent uniform dose (EUD) is the absorbed dose that, when homogeneously given to a tumor, yields the same mean surviving clonogen number as the given non-homogeneous irradiation. EUD is used as an evaluation tool under the assumption that two plans with the same value of EUD are equivalent, and their biological effect on the tumor (clonogen survival) would be the same as the one of a homogeneous irradiation of absorbed dose EUD. In this work, this assumption has been studied, and a figure of merit of its applicability has been obtained. Distributions of surviving clonogen number for homogeneous and non-homogeneous irradiations are found to be different even if their mean values are the same, the figure of merit being greater when there is a wider difference, and the equivalence assumption being less valid. Therefore, EUD can be closer to a uniform dose for some cases than for other ones (high α values, extreme heterogeneity), and the accuracy of the radiobiological indices obtained for evaluation, could be affected. Results show that the equivalence is very sensitive to the choice of radiobiological parameters, and this conclusion has been derived from mathematical properties of EUD.

A quantitative analysis of intensity-modulated radiation therapy plans and comparison of homogeneity indices for the treatment of gynecological cancers

“…The concept of equivalent uniform dose (EUD) for tumors as proposed by Niemierko[3] is one of the methods used to show the relationship between the dose homogeneity and radiobiological effects. [4–6] The equivalent uniform dose is defined as the biologically equivalent dose that, if delivered uniformly, would lead to the same reduction in the tumor volume as the actual dose that has an inhomogeneous distribution. Therefore, if the homogeneity indices are properly calculated, then it may be closely related to the EUD.…”

Physical and Radiobiological Evaluation of Radiotherapy Treatment Plan

“…Many studies have focused on developing a simple index that represents the overall quality of plans [14,19,41,42,67]. However, none of these plans are easily used in a clinic.…”

Bayesian Uncertainty-Directed Dose Finding Designs

“…(): for the chest wall we use a =5 (Woody et al ., ). See Henríquez and Castrillón () for an insightful discussion of EUDs in radiation oncology. For each candidate dose we compute the EUD Q i ( d ).…”

“…Here {z k } is a grid of equally spaced values, and the parameter a is chosen by using the recommendations in Woody et al (2012): for the chest wall we use a = 5 (Woody et al, 2012). See Henríquez and Castrillón (2011) for an insightful discussion of EUDs in radiation oncology. For each candidate dose d ∈ D we compute the EUD Q i .d/.…”