ESTRO 2024 - Abstract Book

S4906

Physics - Quality assurance and auditing

ESTRO 2024

quality assurance for ten patients treated in a ring gantry setup was conducted using ArcCHECK® for a total of 60 fractions.

To validate commissioning of the SGRT system, the findings of optical surface imaging were compared with CBCT scans before applying the SGRT setup for five breast cancer patients.

SMARTTool provided by Varian and MV Cube phantom was used to assess the rotational error monitoring of the SGRT system.

Results:

All tests conducted in compliance with VisionRT's standard installation guidelines demonstrated sub- mm accuracy and less than 1 degree of rotational and translational shifts. A precise transition from virtual isocenters to treatment isocenters was successfully accomplished using SGRT system. Patient specific QA using ArcCHECK® keeping a cut-off 95% gamma with 3%, 3mm was deemed passed for all 10 adaptive patients for all delivered fractions after monitoring with SGRT system. In these pelvic adaptive radiotherapy patients, the SGRT setup mean difference was measured at 0.08 cm vertically, 0.05 cm longitudinally, and 0.07 cm laterally.

For the 5 clinically treated left-sided breast cancer patients utilizing Deep Inspiration Breath Hold (DIBH), the mean SGRT setup difference was found to be 0.29 cm vertically, 0.34 cm longitudinally, and 0.27 cm laterally.

The rotation error monitoring was assessed by SMARTTool and MV Cube phantom. We intentionally introduced a 1° pitch and roll in phantom at 5 different occasions and then cross verified with SGRT, which was successfully able to detect the shift.