(Saturday, 4/7/2018)
Room: Foyer
Purpose: To develop a meaningful metric which can be used to evaluate the quality of IMRT treatment plans (both absolutely and comparatively) using only information from a dose volume histogram.
Methods: Beginning with a simple linear/non linear piecewise function, equations were iteratively developed that were able to significantly differ in value based on a clinical priority, while maintaining a structure in which minor penalty is associated under a threshold, and then a non-linear section which approaches a power function with further deviation from the goal. It was determined additional evaluation structures were needed to give the DVH sufficient information for evaluation, as there are other factors besides organ at risk doses to consider. The equation was designed such that a score of 100 or greater would represent a failing plan.
Results: With judicious application of constants and careful consideration of typical clinical evaluation, the metric developed is capable of roughly approximating the evaluations that would be made by a clinician when reviewing an IMRT plan. More significantly, when comparing competing plans, it can produce a quantitative comparison between the plans to aid in clinical decisions. On final development for this report, penalty values between 0-2 represent a well constructed plan, between 2-20 are acceptable though non ideal, between 20-100 are not meeting (but potentially clinically acceptable).
Conclusion: A meaningful metric can be made using only information retrievable from a DVH. It does require creation of at least one non-traditional structure. The specific metric developed in this investigation still has room for refinement, however it is a reasonably simple set of equations that can be implemented clinically without significant trouble to generate several advantages in IMRT plan design and evaluation.
Funding Support, Disclosures, and Conflict of Interest: Alyzen Medical Physics is the employer of all three authors, James Giltz being an affiliate resident through University of Kentucky. Alyzen has direct interest in integrating this metric into proprietary software.
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