First experimental evaluation of a high-resolution deep silicon photon-counting sensor

Area of Science:

• Medical Imaging
• Detector Physics
• Computational Modeling

Background:

• Current photon-counting computed tomography (CT) detectors face limitations in pixel size (0.3-0.5 mm) due to charge sharing, which degrades dose efficiency and energy resolution.
• Developing smaller pixels is crucial for enhancing CT imaging capabilities.

Purpose of the Study:

• To present measurements of a prototype photon-counting detector designed to achieve theoretical sub-pixel resolution.
• To validate a Monte Carlo (MC) simulation using experimental measurements for further detector development.
• To assess the feasibility of creating ultra-high resolution CT detectors.

Main Methods:

• Measurements were conducted at the DanMAX beamline at MAX IV Lab using a 35 keV photon beam.
• A 2D MC simulation coupled with a charge transport model was used for comparison.
• The prototype detector utilized a minimal number of connected channels to reduce wire bonding complexity.

Main Results:

• Measurements showed good agreement with MC simulations when the photon beam was close to the electrodes.
• Discrepancies were observed as the beam moved further from the electrodes, with induced charge cloud signals increasing linearly.
• Unconnected electrodes were identified as a source of unwanted effects requiring further investigation.

Conclusions:

• The validated MC simulation accurately models detector channel response for photon interactions near electrodes.
• The study indicates promising results for achieving ultra-high resolution in photon-counting CT detectors.
• Further exploration of unconnected electrode effects is necessary for optimizing detector performance.