Digital radiography of the skeleton using a large-area detector based on amorphous silicon technology: image quality and potential for dose reduction in comparison with screen-film radiography.
OBJECTIVE
The purpose of this study was to evaluate a large-area, flat-panel X-ray detector (FD), based on caesium-iodide (CsI) and amorphous silicon (a-Si) with respect to skeletal radiography. Conventional images were compared with digital radiographs using identical and reduced radiation doses.


METHODS
Thirty consecutive patients were studied prospectively using conventional screen-film radiography (SFR; detector dose 2.5 microGy). Digital images were taken from the same patients with detector doses of 2.5, 1.25 and 0.625 microGy, respectively. The active-matrix detector had a panel size of 43 x 43 cm, a matrix of 3 x 3K, and a pixel size of 143 microm. All hard copies were presented in a random order to eight independent observers, who rated image quality according to subjective quality criteria. Results were assessed for significance using the Student's t -test (confidence level 95%).


RESULTS
A statistically significant preference for digital over conventional images was revealed for all quality criteria, except for over-exposure (detector dose 2.5 microGy). Digital images with a 50% dose showed a small, statistically not significant, inferiority compared with SFR. The FD-technique was significantly inferior to SFR at 75% dose reduction regarding bone cortex and trabecula, contrast and overall impression. No statistically significant differences were found with regard to over- and under-exposure and soft tissue presentation.


CONCLUSIONS
Amorphous silicon-based digital radiography yields good image quality. The potential for dose reduction depends on the clinical query.
Völk
M
M
Department of Diagnostic Radiology, University Hospital of Regensburg, Franz-Josef-Strauss-Allee 11, Regensburg, D-93042, Germany.
Strotzer
M
M
Holzknecht
N
N
Manke
C
C
Lenhart
M
M
Gmeinwieser
J
J
Link
J
J
Reiser
M
M
Feuerbach
S
S
D000368:Aged; D001847:Bone Diseases / Q000000981:diagnostic imaging*; D005260:Female; D050723:Fractures, Bone / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods* / Q000592:standards; D012825:Silicon
D012825:Silicon