[Gantry QA Using Three-dimensional Diode Array Detector on O-ring Linear Accelerator].

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• High-precision radiotherapy requires rigorous gantry quality assurance (QA).
• The O-ring type linear accelerator (Halcyon) lacks traditional light fields and lasers for isocenter reference.
• Accurate gantry angle and rotational center verification are critical for patient safety and treatment efficacy.

Purpose of the Study:

• To evaluate the utility of a 3D diode array detector (ArcCHECK) for gantry angle QA.
• To assess the accuracy of the gantry rotational center on the Halcyon linear accelerator.
• To establish a reliable QA method for linacs without conventional referencing tools.

Main Methods:

• Gantry angle and rotational center accuracy were verified using the ArcCHECK 3D diode array.
• Comparisons were made between the Halcyon and a reference linear accelerator (TrueBeam).
• Measurements included specific gantry angles (0°, 90°, 180°, 270°) and rotational accuracy tests.

Main Results:

• The ArcCHECK QA system demonstrated applicability on both TrueBeam and Halcyon accelerators.
• Gantry angle accuracy on Halcyon showed a maximum error of 0.1° compared to nominal values.
• Halcyon's gantry rotation isocenter accuracy was measured at 0.45 mm (clockwise) and 0.41 mm (counterclockwise).

Conclusions:

• The ArcCHECK 3D diode array detector is a useful tool for gantry angle QA on the Halcyon linear accelerator.
• The system provides accurate verification of the gantry rotation center, addressing a key limitation of the Halcyon.
• This QA approach enhances the reliability of high-precision radiotherapy delivery with the Halcyon system.