Online Adaptive Radiotherapy and Opportunity Cost

Purpose/Objective(s)Changes in patient anatomy and tumor geometry pose a challenge to ensuring consistent target coverage and organs-at-risk (OAR) sparing; online adaptive radiotherapy (ART) has been used to account for these inter-fractional changes by facilitating replanning prior to each treatment. This project explores the opportunity cost of CT-based online ART by evaluating the time and human resource requirements for adaptive versus conventional image-guided radiation therapy (IGRT). This study seeks to quantify time requirements for ART and, using time driven activity-based costing (TDABC), determine the cost of this time to determine if the dosimetric benefit is worthwhile.Materials/MethodsOnline ART for pelvic disease sites was evaluated using Ethos based planning technology. Time, which at our facility is best represented by the duration between two cone beam CT (CBCT) scans taken for each adaptive fraction, was used as a broadly applicable and transferable metric, representing the additional time required for adaptive treatment on top of standard IGRT. Dosimetric impact was also considered. All parties (dosimetrist, therapists, physicist, physician) need to be present for the duration of treatment planning given the rapid response time required. Using recently validated TDABC at this facility, the per fraction cost of ART was determined, reflecting the added cost of ART on top of IGRT.ResultsPreliminary data suggests a time difference of approximately 7 versus 24 minutes for daily IGRT and ART, respectively. Each adaptive fraction requires more staffing for the duration of this time delaying completion of other tasks and functionally increasing resource utilization.ConclusionWhile online ART decreases the uncertainty of anatomical shifts, the added human resources required per fraction complicate the workflow of daily treatment and increase expense. This has an even greater impact on the implementation of ART in the context of the alternative payment model. Moreover, online ART removes physicians from clinical time. This opportunity cost is likely to be similar across different disease sites, unlike toxicity benefits which may vary more depending on anatomic location and require further longitudinal studies. Regardless, the implementation of progressively complex radiotherapy technologies, like ART, requires consideration of the time and human resource requirements and subsequent opportunity cost.