Characterization of the IMRT and SBRT performance of a novel biology-guided radiotherapy (BgRT) machine using ArcCHECK
D. Zaks,1 M. Narayanan,1 R. Bassalow,2 O. Volotskova,3 Y. Voroneknko,1 D. Pal,4 D. Rigie,1 J. Burns,1 A. Purwar,1 P. Olcott,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 characterize the IMRT and SBRT performance of the RefleXion™ X1 biology-guided radiotherapy (BgRT) machine using the ArcCHECK (AC) dosimetry device.
Methods: Plans were first generated on the accompanying X1 TPS using CT simulation images of custom inserts designed for use with the AC. The custom inserts represented targets or OARs positioned at specific locations and included a 22 mm diameter sphere and a c-shape target with 26mm axial length with 255° partial annulus with major and minor radii of 27 mm and 12 mm, respectively. The background material in the insert was either a homogenous water medium or a water filled heterogeneous medium with a Styrofoam mesh simulating lung tissue surrounding the target.
A variety of combinations of homogenous and heterogenous inserts and custom target/OARs were used for the experiments, as follows: homogenous insert with a spherical target, homogenous insert with two targets: spherical target + C-shaped target, homogenous insert with C-shaped target, and heterogenous insert with a spherical target.
After dose delivery, the AC software was used to compare the diode dose readings with the DICOM RTDose output of the X1 TPS to determine the accuracy of dose delivery using the Gamma Index, as demonstrated by the Gamma Passing rate (GP).
Results: The following is a representative sample of 5 test cases and the corresponding GP result; 1) C-shape, homogenous insert, 2Gy, GP = 93.4%, 2) C-shape, homogenous insert, 10Gy, GP = 91.0% 3) Sphere, homogenous insert, 10Gy, GP = 99.4% 4) Sphere, heterogenous insert, 10Gy, GP = 96.9% and 5) C-shape + Sphere, homogenous insert, 10Gy, GP = 98.0%.
Conclusion: All IMRT and SBRT test cases met or exceeded the Gamma Index passing rate of at least 90% of the measurement points met or exceeded the 3%/3 mm criteria.