Performance validation of a novel biology-guided radiotherapy (BgRT) TPS following the IAEA-TECDOC-1540 methodology

D. Zaks,¹ R. Bassalow,² S. Maganti,¹ Y. Voroneknko,¹ D. Rigie,¹ O. Volotskova,³ 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 validate the performance of the RefleXion™ X1 biology-guided radiotherapy (BgRT) TPS following the testing methodology outlined in IAEA-TECDOC-1540: Specification and Acceptance Testing of Radiotherapy Treatment Planning Systems.

Methods: Static field plans were developed for each of the tests on the X1 TPS and the resulting RTDOSE DICOM files were exported for comparison to measurements. Dose measurements were made utilizing a commercially available water phantom and solid slab materials simulating water, bone and lung. All ion chambers were calibrated by an ADCL or ADCL-equivalent laboratories.

Results: Depth Doses for field sizes of 10×1, 10×2, 40×1 and 40×2 (cm2) and depths of 10 and 20cm all passed within a 2% tolerance. X/Y profiles for field sizes of 10×1, 10×2, 40×1 and 40×2 (cm2) at 85 cm SSD, 1.5 cm depth all passed within a tolerance of 2%/2mm DD/DTA gamma criteria. Profile widths for 5×1, 5×2 10×1 and 10×2 (cm2) field sizes passed within a 2% (IEC-Y) and 1mm (IEC-X) criteria. Water phantom measurements were also conducted to test the correspondence between calculations and measurements of the following parameters; profile penumbras, build up region, centrally closed MLC leaves, beam symmetry, absolute dose output, field output factor and beam quality.

Variable SSD was tested utilizing solid water and field sizes of 5×1, 5×2, 10×1 and 10×2 (cm2) at SSD=70 cm and depths of 2, 5, 8.5, 13.5 cm. Variable CT and mass densities were tested utilizing two different configurations of solid material slabs simulating embedded lung and bone, and field sizes of 5×1, 5×2, 10×1 and 10×2 (cm2). All measurements passed within the 3% tolerance.

Conclusion: Tests assessing dose calculation accuracy between the X1 TPS and physical measurements of the 6MV photon beam in a variety of test conditions demonstrated compliance to tolerances drawn from well-accepted industry standards.