Log File Based Patient-Specific Quality Assurance Supplement for SRS Mapcheck on Single Isocenter Multiple Target SRS/Fsrs Treatments
Abstract
Purpose
SRS MapCheck has been widely used for SRS pretreatment patient-specific quality assurance (PSQA); however, it requires multiple machine deliveries due to limited array size. To improve the pretreatment PSQA efficiency for Single Isocenter Multiple Target (SIMT) SRS/fractioned SRS (fSRS) treatments, a log file-based supplement workflow has been developed.
Methods
20 patient treatment plans (10 SRS and 10 fSRS) delivered by Varian Edge Linac were included in the analysis retrospectively. Log files from the pretreatment PSQA delivery were obtained to reconstruct the RT Plan with the delivered MLC/jaw positions, gantry, collimator, and couch angles at each control point. We utilized an independent dose calculation algorithm (RadCalc) to compare calculated dose distributions from (1) RayStation treatment plan, (2) secondary dose calculation of the RayStation treatment plan, and (3) delivery-based log files recorded during pretreatment PSQA delivery. We quantified the differences in isocenter dose and the dose from each beam segment.
Results
The differences between the doses calculated with secondary dose calculation of the RayStation treatment plan and delivery-based log files recorded during pretreatment PSQA delivery were minimal, with most differences being within 2%. The correlation was significant (p = 0.0302, r2 = 0.235) between the isocenter dose differences of delivery-based log files versus treatment planning system, and the dose differences of secondary dose calculations versus treatment planning system.
Conclusion
A log file-based supplement PSQA workflow can provide 3D dose distribution to all targets and organ-at-risks from a single pretreatment delivery and improve the PSQA efficiency by reducing the manual and machine time.