# Back-irradiated flat panel imager with avalanche gain

> **NIH NIH R01** · STATE UNIVERSITY NEW YORK STONY BROOK · 2020 · $613,128

## Abstract

Summary
The objective of this proposal is to develop a back-irradiated (BI) active matrix flat-panel
imager (AMFPI) with programmable avalanche gain. It will have wide dynamic range, high
detective quantum efficiency (DQE) and high frame rate. The proposed detector employs
three major components: a structured cesium iodide (CsI) scintillator with thickness up to
twice that in existing AMFPI; an avalanche amorphous selenium (a-Se) photoconductor,
HARP (High-gain Avalanche Rushing amorphous Photoconductor), to convert the optical
photons from CsI to charge and provide a programmable gain; and a large area metal-oxide
(MO) thin film transistor (TFT) array to read out the image electronically at 100 frames per
second (fps). The proposed detector is called BI-SHARP-AMFPI (Back-Irradiated Scintillator-
HARP Active Matrix Flat-Panel Imager). It is capable of producing x-ray quantum noise
limited images at the lowest dose expected for x-ray imaging (0.1 μR), which virtually has
only one x-ray photon per pixel. For high dose applications (e.g. radiography) the gain of
HARP will be decreased to ensure wide dynamic range without detector saturation. With BI,
the majority of x-rays interact closer to the optical sensor, thereby permitting much thicker CsI
to improve DQE at high kVp used in CBCT. The carrier mobility in MOTFT is more than an
order of magnitude higher than a-Si TFT, permitting readout rate up to 100 fps, which is
desired in CBCT. The objectives will be accomplished through the following three specific
aims: (1) Optimize BI-SHARP-AMFPI detector configuration; (2) Develop the optimal HARP
sensor structure for BI-SHARP-AMFPI; (3) Develop prototype BI-SHARP-AMFPI to prove
feasibility and validate design considerations. Once these aims are accomplished a new
AMFPI ready for clinical translation will be resulted, and permit major advancements in the
most demanding x-ray imaging application: real-time imaging and CBCT for guidance of
interventional procedures.

## Key facts

- **NIH application ID:** 9832201
- **Project number:** 5R01EB026267-03
- **Recipient organization:** STATE UNIVERSITY NEW YORK STONY BROOK
- **Principal Investigator:** Wei Zhao
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $613,128
- **Award type:** 5
- **Project period:** 2018-03-01 → 2021-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9832201

## Citation

> US National Institutes of Health, RePORTER application 9832201, Back-irradiated flat panel imager with avalanche gain (5R01EB026267-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9832201. Licensed CC0.

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