DocumentCode :
1176480
Title :
Amorphous silicon pixel layers with cesium iodide converters for medical radiography
Author :
Jing, T. ; Goodman, C.A. ; Drewery, J. ; Cho, G. ; Hong, W.S. ; Lee, H. ; Kaplan, S.N. ; Mireshghi, A. ; Perez-Mendez, V. ; Wildermuth, D.
Author_Institution :
Lawrence Berkeley Lab., CA, USA
Volume :
41
Issue :
4
fYear :
1994
fDate :
8/1/1994 12:00:00 AM
Firstpage :
903
Lastpage :
909
Abstract :
We describe the properties of evaporated layers of cesium iodide (thallium activated) deposited on substrates that enable easy coupling to amorphous silicon pixel arrays. The CsI(Tl) layers range in thickness from 65 to 220 μm. We used the two-boat evaporator system to deposit CsI(Tl) layers. This system ensures the formation of the scintillator film with homogenous thallium concentration which is essential for optimizing the scintillation light emission efficiency. The Tl concentration was kept to 0.1-0.2 mole percent for the highest light output. Temperature annealing can affect the microstructure as well as light output of the CsI(Tl) film. 200-360°C temperature annealing can increase the light output by a factor of two. The amorphous silicon pixel arrays are p-i-n diodes approximately 1 μm thick with transparent electrodes to enable them to detect the scintillation light produced by X-rays incident on the CsI(Tl). Digital radiography requires a good spatial resolution. This is accomplished by making the detector pixel size less than 50 μm. The light emission from the CsI(Tl) is collimated by techniques involving the deposition process on patterned substrates. We have measured MTF of greater than 12 line pairs per mm at the 10% level
Keywords :
X-ray detection and measurement; amorphous semiconductors; annealing; caesium compounds; diagnostic radiography; elemental semiconductors; p-i-n diodes; position sensitive particle detectors; scintillation counters; semiconductor counters; silicon; thallium; 200 to 300 C; CsI converters; CsI:Tl; Si; X-rays; amorphous Si pixel layers; digital radiography; evaporated layers; light output; medical radiography; microstructure; p-i-n diodes; pixel size; scintillation light emission efficiency; scintillator film; temperature annealing; transparent electrodes; two-boat evaporator system; Amorphous silicon; Annealing; Electrodes; Microstructure; Optical arrays; P-i-n diodes; Solid scintillation detectors; Substrates; Temperature; X-ray detection;
fLanguage :
English
Journal_Title :
Nuclear Science, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9499
Type :
jour
DOI :
10.1109/23.322829
Filename :
322829
Link To Document :
بازگشت