Investigation of an active matrix flat-panel imager (AMFPI) employing a thin layer of polycrystalline HgI2 photoconductor for mammographic imaging

Active matrix flat-panel imagers (AMFPIs) have become ubiquitous across a wide variety of medical x-ray imaging applications. While AMFPIs based on both direct and indirect detection of the incident radiation offer many advantages, their performance is limited by relatively modest system gain compared to electronic additive noise. The effects of this limitation upon imaging performance become particularly apparent at lower exposures and/or at higher spatial frequencies. One potential strategy for overcoming this limitation involves the use of a high gain photoconductor such as mercuric iodide (HgI2) which has the potential to improve system gain by up to an order of magnitude compared to that provided by a-Se, the only photoconductor material presently used in direct detection AMFPIs. In this paper, preliminary results from an investigation of the performance of a prototype direct detection AMFPI employing a relatively thin layer of polycrystalline HgI2 created through a screen-printing method and operated under mammographic irradiation conditions are presented. The results encourage further examination of this strategy to improve the performance of AMFPIs designed for mammography.

[1]  Larry Partain,et al.  Mercuric iodide medical imagers for low-exposure radiography and fluoroscopy , 2004, SPIE Medical Imaging.

[2]  Qihua Zhao,et al.  Active pixel imagers incorporating pixel-level amplifiers based on polycrystalline-silicon thin-film transistors. , 2009, Medical physics.

[3]  Qihua Zhao,et al.  Systematic investigation of the signal properties of polycrystalline HgI2 detectors under mammographic, radiographic, fluoroscopic and radiotherapy irradiation conditions , 2005, Physics in medicine and biology.

[4]  Qihua Zhao,et al.  Performance of a high fill factor, indirect detection prototype flat-panel imager for mammography. , 2007, Medical physics.

[5]  A Fenster,et al.  A spatial-frequency dependent quantum accounting diagram and detective quantum efficiency model of signal and noise propagation in cascaded imaging systems. , 1994, Medical physics.

[6]  Larry E. Antonuk,et al.  An asynchronous, pipelined, electronic acquisition system for Active Matrix Flat-Panel Imagers (AMFPIs) , 1999 .

[7]  Safa Kasap,et al.  X-ray sensitivity of a-Se for x-ray imaging with electrostatic readout , 1998 .

[8]  Qihua Zhao,et al.  Investigation of the signal behavior at diagnostic energies of prototype, direct detection, active matrix, flat-panel imagers incorporating polycrystalline HgI2. , 2008, Physics in medicine and biology.

[9]  Arokia Nathan,et al.  Active pixel image sensor for large-area medical imaging , 2003, SPIE Medical Imaging.

[10]  Yi Wang,et al.  Evaluation of novel direct- and indirect-detection active matrix flat-panel imagers (AMFPIs) for mammography , 2003, SPIE Medical Imaging.

[11]  Kunio Doi,et al.  A simple method for determining the modulation transfer function in digital radiography , 1992, IEEE Trans. Medical Imaging.

[12]  J H Siewerdsen,et al.  Strategies to improve the signal and noise performance of active matrix, flat-panel imagers for diagnostic x-ray applications. , 2000, Medical physics.

[13]  Wei Zhao,et al.  The x-ray sensitivity of amorphous selenium for mammography. , 2002, Medical physics.

[14]  Kenkichi Tanioka,et al.  Indirect flat-panel detector with avalanche gain: fundamental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix flat panel imager). , 2005, Medical physics.

[15]  Qihua Zhao,et al.  Performance evaluation of polycrystalline HgI2 photoconductors for radiation therapy imaging. , 2010, Medical physics.

[16]  Qihua Zhao,et al.  System performance of a prototype flat-panel imager operated under mammographic conditions. , 2003, Medical physics.

[17]  M J Yaffe,et al.  Analysis of the spatial-frequency-dependent DQE of optically coupled digital mammography detectors. , 1994, Medical physics.

[18]  C. I. Coleman,et al.  Image Science: Principles, Analysis and Evaluation of Photographic-type Imaging Processes , 1975 .