A high-resolution large-area detector for quality assurance in radiotherapy

Area of Science:

• Medical Physics
• Radiation Detection
• Particle Therapy

Background:

• Hadron therapy utilizes protons and carbon ions for precise cancer treatment.
• Accurate dosimetry and sub-millimetre spatial resolution are critical for effective hadron therapy.
• Current detectors face challenges in meeting these stringent requirements.

Purpose of the Study:

• To design, fabricate, and test a novel Gas Electron Multiplier (GEM) coupled to a thin-film transistor (TFT) detector.
• To evaluate the detector's performance in measuring various radiation types used in therapy.
• To assess the detector's suitability for quality assurance in hadron therapy.

Main Methods:

• Development of a GEM-TFT detector with a 60x80 mm² active area and 200 ppi resolution.
• Performance testing with low-energy X-rays (40 kVp), high-energy photons (6 MeV), and clinical beams of protons and carbon ions.
• Measurement of secondary electrons produced by GEMs to determine spatial resolution and linearity.

Main Results:

• The GEM-TFT detector successfully detected X-rays, high-energy photons, protons, and carbon ions.
• Achieved sub-millimetre spatial resolution and a linear response for proton currents from 18 pA to 0.7 nA.
• Demonstrated the detector's compact, scalable, and radiation-hard characteristics.

Conclusions:

• The novel GEM-TFT detector shows significant promise for quality assurance in hadron therapy.
• Its ability to accurately measure diverse radiation types supports enhanced treatment precision.
• Further corrections for detector defects could improve dose uniformity and LET dependence studies.