Entrance window design parameters for high-pressure gas x-ray imaging detectors

Area of Science:

• Medical Imaging Physics
• High-Pressure Systems Engineering
• X-ray Detector Technology

Background:

• Gas ionization x-ray detectors offer high spatial and contrast resolution.
• Conventional pressure vessel designs lead to primary beam loss and reduced detective quantum efficiency due to window integration.
• High operating pressures (up to 100 atm) pose significant mechanical challenges for detector window integrity.

Purpose of the Study:

• To design a gas chamber cover plate that isolates the x-ray entrance window from tensile stresses.
• To optimize window geometry (thickness, curvature, fillet radius) for high-pressure gas ionization x-ray detectors.
• To identify an optimal window design for a prototype digital x-ray imaging detector.

Main Methods:

• Developed a novel cover plate design to mechanically isolate the x-ray entrance window.
• Fabricated test windows from aluminum [6061-T651] with varying geometric parameters.
• Subjected windows to pressures up to 400 atm to determine rupture points and assess performance.

Main Results:

• Optimized windows demonstrated rupture pressures exceeding 500 atm for a 1.0 cm wide x-ray beam.
• Achieved high x-ray transmittances of up to 93.4% for a 120 kVp tungsten anode spectrum.
• The novel design successfully mitigated primary beam loss and maintained detector efficiency.

Conclusions:

• The developed window design effectively addresses mechanical stress challenges in high-pressure x-ray detectors.
• This breakthrough enables enhanced detective quantum efficiency and improved imaging performance in digital x-ray systems.
• The optimized windows are suitable for demanding applications requiring high spatial resolution and contrast.