A xenon ionization detector for scanned projection radiography: 95-channel prototype evaluation

Area of Science:

• Medical Imaging
• Radiological Physics
• Detector Technology

Background:

• Computed tomography (CT) xenon ionization detectors are established but can be complex to construct.
• Screen/film systems require higher radiographic contrast for structure detection.
• Existing detectors may not offer optimal spatial resolution or dose efficiency for certain applications.

Purpose of the Study:

• To design, construct, and test a novel 95-channel prototype xenon ionization detector for scanned projection radiography (SPR).
• To evaluate the detector's spatial resolution, dose efficiency, and ease of construction.
• To compare the performance of the new detector against a conventional screen/film system.

Main Methods:

• Developed a prototype detector with parallel plates separated by a 2-mm gap filled with xenon gas at 2 MPa.
• Utilized a high-voltage electrode and a circuit board with etched collector strips forming 0.5 mm wide channels.
• Measured system noise, performed detector channel calibration, and imaged phantoms and tissue samples.

Main Results:

• The SPR xenon ionization detector demonstrated higher spatial resolution and improved dose efficiency over screen/film.
• Detected structures with 0.17% radiographic contrast, compared to 2% for screen/film, at a low exposure.
• Achieved a limiting resolution of 2.0 lp/mm at 1.6 magnification and comparable low-contrast sensitivity with reduced exposure for mammoplasty images.

Conclusions:

• The prototype xenon ionization detector is a promising advancement for scanned projection radiography.
• It offers significant advantages in spatial resolution and dose efficiency, enabling detection of lower contrast details.
• Further development could enhance high-contrast detail reproduction, potentially improving diagnostic capabilities.