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MO‐FG‐202‐05: Identifying Treatment Planning System Errors in IROC‐H Phantom Irradiations
Author(s) -
Kerns J,
Followill D,
Howell R,
Melancon A,
Stingo F,
Kry S
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4957307
Subject(s) - imaging phantom , linear particle accelerator , radiation treatment planning , nuclear medicine , quality assurance , medicine , mathematics , computer science , medical physics , radiation therapy , beam (structure) , physics , surgery , optics , external quality assessment , pathology
Purpose: Treatment Planning System (TPS) errors can affect large numbers of cancer patients receiving radiation therapy. Using an independent recalculation system, the Imaging and Radiation Oncology Core‐Houston (IROC‐H) can identify institutions that have not sufficiently modelled their linear accelerators in their TPS model. Methods: Linear accelerator point measurement data from IROC‐H's site visits was aggregated and analyzed from over 30 linear accelerator models. Dosimetrically similar models were combined to create “classes”. The class data was used to construct customized beam models in an independent treatment dose verification system (TVS). Approximately 200 head and neck phantom plans from 2012 to 2015 were recalculated using this TVS. Comparison of plan accuracy was evaluated by comparing the measured dose to the institution's TPS dose as well as the TVS dose. In cases where the TVS was more accurate than the institution by an average of >2%, the institution was identified as having a non‐negligible TPS error. Results: Of the ∼200 recalculated plans, the average improvement using the TVS was ∼0.1%; i.e. the recalculation, on average, slightly outperformed the institution's TPS. Of all the recalculated phantoms, 20% were identified as having a non‐negligible TPS error. Fourteen plans failed current IROC‐H criteria; the average TVS improvement of the failing plans was ∼3% and 57% were found to have non‐negligible TPS errors. Conclusion: IROC‐H has developed an independent recalculation system to identify institutions that have considerable TPS errors. A large number of institutions were found to have non‐negligible TPS errors. Even institutions that passed IROC‐H criteria could be identified as having a TPS error. Resolution of such errors would improve dose delivery for a large number of IROC‐H phantoms and ultimately, patients.