A pixel detector-based single photon-counting system as fast spectrometer for diagnostic X-ray beams

Area of Science:

• Medical Imaging
• Semiconductor Detectors
• Digital Radiography

Background:

• Semiconductor pixel detectors and read-out electronics have advanced, enabling new single photon-counting imaging systems.
• These systems represent a significant advancement over existing digital radiography technologies.
• Key advantages include direct photon energy conversion and electronic noise rejection via thresholding.

Purpose of the Study:

• To present a novel single photon-counting imaging system prototype.
• To highlight the system's high imaging performance capabilities.
• To demonstrate its potential application as a fast spectrometer for X-ray diagnostics.

Main Methods:

• Developed a system using a 300-microm silicon pixel detector bump-bonded to a Medipix2 read-out chip.
• The detector array consists of 256 x 256 pixels with a 55-microm pitch.
• Each pixel features a low-noise preamplifier, two pulse height discriminators, and a 14-bit counter, with a maximum counting rate of 1 MHz.

Main Results:

• The system achieves high spatial and contrast resolution due to direct conversion and noise rejection.
• Deep integration techniques enable smaller pixel sizes and faster read-out speeds.
• The system demonstrated potential as a fast spectrometer by analyzing diagnostic X-ray beam energy spectra.

Conclusions:

• Single photon-counting systems offer superior performance for digital radiography.
• The presented system's design, utilizing Medipix2, is suitable for high-flux diagnostic radiology.
• The 'window mode' capability enables advanced applications like fast X-ray spectroscopy.