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Scintillator high-gain avalanche rushing photoconductor active-matrix flat panel imager: zero-spatial frequency x-ray
1Department of Radiation Oncology, Sunnybrook Health Sciences Center, Toronto, Ontario, Canada.
Medical Physics
|November 7, 2012
Summary
This study demonstrates a new solid-state x-ray sensor, the scintillator high-gain avalanche rushing photoconductor active matrix flat panel imager (SHARP-AMFPI), offering a wide dynamic range for medical imaging. Its programmable avalanche gain ensures quantum noise-limited operation across all relevant x-ray exposures.
Area of Science:
- Medical Imaging
- Solid-State Physics
- X-ray Detection
Background:
- Current x-ray imaging technologies face limitations in dynamic range and noise performance.
- Solid-state sensors offer potential for improved imaging characteristics.
- Avalanche gain mechanisms are being explored for enhanced x-ray detection sensitivity.
Purpose of the Study:
- To investigate the feasibility of a novel solid-state x-ray imaging sensor: scintillator high-gain avalanche rushing photoconductor active matrix flat panel imager (SHARP-AMFPI).
- To evaluate the inherent x-ray detection properties of the SHARP sensor.
- To demonstrate the wide dynamic range achievable through programmable avalanche gain.
Main Methods:
- Development of a distributed resistive layer (DRL) for stable avalanche gain in a high-gain avalanche rushing photoconductor (HARP).
- Theoretical and experimental investigation of signal and noise properties of HARP-DRL for optical photon detection.
- Fabrication of a solid-state SHARP x-ray sensor by coupling HARP-DRL with a cesium iodide (CsI) scintillator.
- Measurement of x-ray sensitivity and dynamic range as a function of avalanche gain.
Main Results:
- Stable avalanche gain was achieved in HARP-DRL, with noise characteristics aligning with theoretical predictions.
- The additional noise from avalanche gain in HARP-DRL was found to be negligible when coupled with CsI for x-ray detection.
- The SHARP sensor exhibited avalanche gain dependence consistent with optical measurements, enabling a very wide dynamic range covering all clinical radiography/fluoroscopy exposures.
Conclusions:
- The HARP-DRL sensor facilitates the practical implementation of a SHARP solid-state x-ray sensor.
- Quantum noise-limited operation is achievable throughout the entire range of clinically relevant x-ray exposures.
- This represents a significant advancement toward the development of a SHARP-AMFPI x-ray flat-panel imager.
