Poster — Wed Eve—17: Detrimental Dose: A Proposed Metric to Score Incidents in Radiation Therapy

Public awareness of radiation therapy is increasing, and incidents related to radiation therapy delivery are receiving increased public scrutiny. There is a growing interest within the professional community in systems for reporting errors in radiation therapy and communicating their significance. Many of the reporting systems proposed to‐date use decision trees to stratify incidents according to differing levels of severity, with the result that it is difficult to compare incidents between disparate systems. We propose a new metric that uses absorbed dose as a basis for estimating the anticipated detriment of a radiation therapy error in much the same way as dose is used to determine risk in radiation protection. The formulation takes into account the magnitude of the dose error and the volume of tissue unintentionally irradiated, modified by dimensionless quantities that account for tissue response (Tissue Sensitivity) and patient‐specific quality of life factors (Severity Index). The resulting quantity, which we have termed “Detrimental Dose”, should be applicable to describing the severity of an adverse event regardless of the magnitude of the error. Using specific examples of recent radiation therapy incidents, we illustrate how this new metric can be used to estimate the severity of a misadministration of dose. We believe that such a system can provide a unified framework for reporting and assessment of radiation therapy errors.