(Saturday, 4/7/2018)
Room: Foyer
Purpose: To investigate results from initial usage of DoseCHECK, PerFRACTION and ArcCHECK patient QA products from Sun Nuclear Corporation (SNC).
Methods: At a new clinic, the first twenty-three VMAT patient plans (RayStation TPS and Elekta Infinity linac) were selected for analysis of pass-rate consistency amongst multiple patient pre-treatment QA products offered by SNC. For each patient, gamma analysis criteria across products were consistent (typically 3%/3mm/10% threshold). The investigated products were: (1) DoseCHECK (3D dose calculation engine using the patient CT, RT Structure Set and RT Plan from the TPS) [dc3d]; (2) PerFRACTION 3D with logs only (3D dose calculation engine using the patient CT, RT Structure Set, RT Plan and log files created using an iCom interface to the linac during delivery) [pf0logs]; (3) PerFRACTION 3D with EPID (CT, RT Structure Set, RT Plan, logs and EPID images captured by the Elekta iView panel to verify actual MLC position) [pf0epid]; and (4) ArcCHECK [ac]. Reference dose for analysis was either the TPS dose on the patient CT (for [dc3d], [pf0logs], [pf0epid]) or TPS dose on the ArcCHECK phantom (for [ac]).
Results: The Friedman rank sum test yielded a p-value ≤ 0.0001 indicating a difference amongst product performances. Linear correlation (R² = 0.994) was observed between [dc3d] and [pf0logs] for the paired sample. In keeping with the statistical testing, visual examination of pass-rate performance for [pf0epid] vs. [dc3d], [ac] vs. [dc3d], and [ac] vs. [pf0epid] all illustrated little discernible correlation with R² ≤ 0.2 for all.
Conclusion: EPID image usage introduced a marked PerFRACTION performance difference from that obtained using log files only. ArcCHECK performance was uncorrelated to PerFRACTION 3D regardless of EPID image usage. Future work will investigate 2D performance of PerFRACTION 2D using an EPID calibrated for absolute dose and calibration technique influence upon ArcCHECK.
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