Development of a Real-Time Pixel Array-Type Detector for Ultrahigh Dose-Rate Beams

Area of Science:

• Medical Physics
• Radiation Oncology
• Detector Technology

Background:

• Ultrahigh dose-rate (UHDR) radiation therapy research is advancing, but experimental data on 2D dose-rate distributions are scarce.
• Conventional pixel detectors cause significant beam loss, hindering accurate measurements in UHDR applications.
• Real-time monitoring of UHDR proton beams is crucial for quality assurance and treatment efficacy.

Purpose of the Study:

• To develop and evaluate a pixel array-type detector system for real-time measurement of 2D dose-rate distributions in UHDR proton beams.
• To assess the detector's effectiveness in minimizing beam loss and ensuring accurate beam position and profile measurements.
• To validate the system's performance under UHDR conditions using experimental and simulation methods.

Main Methods:

• Developed a pixel array detector with adjustable gaps and a data acquisition system.
• Measured UHDR proton beams (45 MeV, 10-70 nA) using an MC-50 cyclotron.
• Employed Monte Carlo simulations and experimental measurements to determine collection efficiency and optimize detector parameters (gap, high voltage).

Main Results:

• Confirmed UHDR conditions, with dose rates exceeding 300 Gy/s at 45 MeV and 70 nA.
• Optimized detector settings (2 mm gap, 1000 V) achieved less than 1% loss in collection efficiency for UHDR beams.
• Real-time beam position measurement accuracy within 2% was achieved at five reference points.

Conclusions:

• A novel beam monitoring system capable of real-time UHDR proton beam measurement has been successfully developed.
• The developed system accurately measures beam position and profile, addressing critical needs in UHDR radiation therapy research.
• The system's ability to minimize beam loss and provide real-time data enhances its utility for advanced radiotherapy applications.