Purpose: The Radiotherapy Outcomes Explorer (ROE), an open source plugin to CERR, can evaluate and output dose/volume and TCP/NTCP metrics from large cohorts of treatment plans in batch mode, and can be used to estimate accrual rates of potential protocols where such metrics restrict patient eligibility. This ability would be enhanced if ROE’s capacity to rescale plan doses could be used to explore eligibility in the prescription space. Here we compare eligibility rates of delivered and rescaled plans for a protocol currently being developed.
Methods: The proposed protocol would test the efficacy of an alternative treatment for esophagitis after receiving radiotherapy for thoracic tumors utilizing various prescriptions. ROE was used to investigate the eligible proportion of 198 late stage NSCLC patients receiving 50-70 (median:62) Gy in 1.8-2 Gy fractions using chemotherapy combined with IMRT between 2004-14. Patients are eligible at time of treatment planning if at high risk for esophagitis by dose volume criteria (V50Gy≥15%). Each treatment plan was rescaled to the other prescriptions in the cohort. Eligible rescaled plans were noted and for each prescription, and the eligible proportion calculated. The proportions in the scaled plans were then compared to those in the original plans available at each prescription. Due to small numbers of plans at some prescriptions, the comparisons were consolidated.
Results: Accuracy of assessment of protocol eligibility using scaled plans decreased with difference of the scaling factor from one. Nevertheless, in all but the lowest scaled prescriptions eligibility rates differed from those in unscaled plans by ≤ 26%, and usually < 10%.
Conclusion: Our results show that scaled plans in ROE can be used to assess protocol eligibility rates, which differ by <26% from unscaled plans in all but the lowest prescriptions.
Funding Support, Disclosures, and Conflict of Interest: Authors declare the following employment relationships and funding sources. Consultant: MORE Health. Research grants: CivaTech Oncology, Varian Medical Systems, Boehringer Ingelheim, Astra Zeneca, Pfizer, Merck. Advisory board: Simphotek, Boehringer Ingelheim, Merck, GRAIL. Honoraria: Varian Medical systems.
Computer Software, Radiation Therapy, Dose Volume Histograms