Developing a Quality Index for Dose-Volume Histograms Based on Physician Preference

Abstract

The purpose of this study was to create a DVH quality index that can be used as a comparison tool between two separate plans and as a clinical workflow tool to improve plan quality resulting in better patient outcome. To create this DVH quality index, physician preference was used as the basis of the dose-volume relationship quantification rather than biological models since physicians are the ones who drive plan quality within in a clinic. An intra-patient observership study was created to gather the qualitative and quantitative from radiation oncologists who ranked a set of plans of varying plan quality from a specific patient. The qualitative data gave rise to the formation of the algorithm to produce a DVH quality index while the quantitative data drove the weighting factors within the algorithm. The intra-patient study validated the algorithms ability to determine the best DVH among separate plans from a specific patient. An inter-patient study was then introduced to validate the DVH quality index across the spectrum of scores given by the algorithm by comparing the algorithm's rank list with the oncologists' rank lists. These studies used spearman rank correlation tests to compare the rank lists between the algorithm and the oncologists. The perfect index that the algorithm can calculate is 10. Subsequently any penalization that occurs within the DVH will be subtracted away from the score of 10 with no bottom limit. For the intra-patient study, the mean correlation coefficient of our group's algorithm with the oncologists is 0.726 and the mean correlation coefficient of the oncologists with each other oncologist is 0.564. In the inter-patient study, the correlations proved to be stronger where the mean correlation coefficient of the algorithm with the oncologists is 0.822 and the mean correlation coefficient of the oncologists with each other is 0.699. Since our mean correlation coefficients with the oncologists for the intra-patient and the inter-patient study is higher than the mean correlation coefficient of the oncologists with each other, we can state that we represent a general oncologist within the hospital system when ranking DVHs.