Improved temporal performance and optical quantum efficiency of avalanche amorphous selenium for low dose medical imaging

Corey Orlik; Sébastien Léveillé; Salman M. Arnab; Adrian F. Howansky; Jann Stavro; Scott Dow; Safa Kasap; Kenkichi Tanioka; Amir H. Goldan; Wei Zhao

doi:10.1117/1.JMI.11.1.013502

13 January 2024 Improved temporal performance and optical quantum efficiency of avalanche amorphous selenium for low dose medical imaging

Corey Orlik, Sébastien Léveillé, Salman M. Arnab, Adrian F. Howansky, Jann Stavro, Scott Dow, Safa Kasap, Kenkichi Tanioka, Amir H. Goldan, Wei Zhao

Author Affiliations +

Journal of Medical Imaging, Vol. 11, Issue 1, 013502 (January 2024). https://doi.org/10.1117/1.JMI.11.1.013502

Abstract

Purpose

Active matrix flat panel imagers (AMFPIs) with thin-film transistor arrays experience image quality degradation by electronic noise in low-dose radiography and fluoroscopy. One potential solution is to overcome electronic noise using avalanche gain in an amorphous selenium (a-Se) (HARP) photoconductor in indirect AMFPI. In this work, we aim to improve temporal performance of HARP using a novel composite hole blocking layer (HBL) structure and increase optical quantum efficiency (OQE) to CsI:Tl scintillators by tellurium (Te) doping.

Approach

Two different HARP structures were fabricated: Composite HBL samples and Te-doped samples. Dark current and optical sensitivity measurements were performed on the composite HBL samples to evaluate avalanche gain and temporal performance. The OQE and temporal performance of the Te-doped samples were characterized by optical sensitivity measurements. A charge transport model was used to investigate the hole mobility and lifetime of the Te-doped samples in combination with time-of-flight measurements.

Results

The composite HBL has excellent temporal performance, with ghosting below 3% at 10 mR equivalent exposure. Furthermore, the composite HBL samples have dark current <10−10 A/cm2 and achieved an avalanche gain of 16. Te-doped samples increased OQE from 0.018 to 0.43 for 532 nm light. The addition of Te resulted in 2.1% first-frame lag, attributed to hole trapping within the layer.

Conclusions

The composite HBL and Te-doping can be utilized to improve upon the limitations of previously developed indirect HARP imagers, showing excellent temporal performance and increased OQE, respectively.

Citation Download Citation

Corey Orlik, Sébastien Léveillé, Salman M. Arnab, Adrian F. Howansky, Jann Stavro, Scott Dow, Safa Kasap, Kenkichi Tanioka, Amir H. Goldan, and Wei Zhao "Improved temporal performance and optical quantum efficiency of avalanche amorphous selenium for low dose medical imaging," Journal of Medical Imaging 11(1), 013502 (13 January 2024). https://doi.org/10.1117/1.JMI.11.1.013502

Received: 20 June 2023; Accepted: 20 December 2023; Published: 13 January 2024

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KEYWORDS

Tellurium

Selenium

Quantum efficiency

Quantum optics

Dark current

Electrodes

Quantum measurement

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