Validation of ArcCHECK for use with a novel ring gantry-based biology-guided radiotherapy (BgRT) machine
D. Zaks,1 M. Narayanan,1 R. Bassalow,2 O. Volotskova,3 C. Huntzinger,1 S. Shirvani,1 S. Mazin,1 G. Kuduvalli1
1RefleXion Medical, Hayward, CA; 2Northwest Medical Physics Center, Silverdale, WA; 3Sutter Health, Berkeley, CA; 4GE Healthcare, Menlo Park, CA
AAPM/COMP Annual Scientific Meeting, Virtual (2020).
Purpose: To validate the ArcCheck (AC) dosimetry device as a dosimetry tool to measure the dose delivered by a the RefleXion™ X1 biology-guided radiotherapy (BgRT) machine.
Methods: Seven IMRT and SBRT plans were created in the X1 TPS. The plans included a centered 8×5 cm cylinder, a centered 25 mm ball, a centered 40 mm ball, an off axis 25 mm ball, an off axis 40 mm ball, 2 symmetrically offset 25 mm balls, and an off-axis C-shape. The seven plans were delivered to the assembly of ArcCheck, multi-plug, ion chamber, and film. The AC multi-plug is designed to hold ion chambers and film within the AC cavity. For each of the delivered plans, the data was recorded by AC, calibrated A14SL ion chambers and EBT3 Gafchromic film. The point doses and dose distribution extracted from the film were compared to the dose predicted by the treatment plan. The overall passing rate on the AC absolute surface dose was calculated by comparison to the calculated DICOM RTDose object from the X1 TPS. The overall passing rate on the 2D relative film dose was compared with a 2D plane of the 3D DICOM RTDose object, as evaluated in MATLAB. Both passing rates were calculated at a 3%/3mm gamma.
Results: The three on-axis test objects (8×5 cylinder, 25mm ball, 40mm ball) had passing rates of 99.5%, 98.8% and 99.7% with film and 97.4%, 100%, and 92.3% with AC. The four off-axis test objects (25mm ball, 40mm ball, 2 balls, C shape) had passing rates of 93%, 95.6%, 93.3% and 92.3% respectively.
Conclusion: All 7 test cases passed the test criteria, validating the use of AC as a dosimetry tool for use with the novel ring-based architecture of the X1 biology-guided radiotherapy machine.