A novel high-resolution 2D silicon array detector for small field dosimetry with FFF photon beams

Area of Science:

• Medical Physics
• Radiation Oncology
• Detector Technology

Background:

• Flattening filter free (FFF) beams are increasingly utilized in stereotactic radiotherapy (SRT).
• Accurate dosimetry is crucial for effective SRT delivery.
• Novel detector technologies are needed to characterize FFF beams.

Purpose of the Study:

• To evaluate the performance of the "Octa" monolithic silicon array detector with 6 and 10 MV FFF beams.
• To compare the Octa detector's performance against commercially available detectors for small field dosimetry.
• To assess the dosimeter's suitability for stereotactic radiotherapy applications.

Main Methods:

• Investigated output factors (OFs), percentage depth-dose (PDD), dose profiles (DPs), and dose per pulse (DPP) dependence.
• Benchmarked results against commercially available detectors for small field dosimetry.
• Measured cross-plane, in-plane, and diagonal dose profiles with high spatial resolution and real-time readout.

Main Results:

• The Octa detector demonstrated 'correction-free' performance for OFs and PDD measurements across investigated beam qualities.
• OFs were accurate within 3% and PDD values within 2% compared to benchmarks.
• A dose per pulse dependence was identified but correctable for quality assurance.

Conclusions:

• The Octa detector exhibits robust performance for relative dosimetry across various beam qualities and dose per pulses.
• Its high-resolution 2D dose map characterization makes it a unique real-time detector for small field dosimetry.
• The technology supports the use of FFF beams in SRT, offering advanced capabilities over predecessors.