Evaluating phantom image quality parameters to optimise patient radiation dose in dental digital radiology.
Our objective was to obtain images of a predictable level of quality using an intraoral X-ray system with digital imaging, avoiding patient overexposure. A polymethylmethacrylate (PMMA) physical test phantom was imaged at different exposure times and at various PMMA thicknesses using a dental imaging coupled charge device. Two identical regions of interest (ROIs) were chosen in every image file, and quality was numerically evaluated by measuring high-contrast spatial resolutions, low-contrast thresholds and signal-to-noise ratios. In addition, three practitioners proposed personal quality scores by image inspection. Numerical contents in the ROIs, related to the image quality, were plotted against exposure time. From here, a simple expression linking the exposure time with the thickness to obtain images of comparable quality was deduced. As a result, the optimum exposure time for imaging with a predictable level of quality can be inferred. The potential effect could imply savings above 1000 man Sv, roughly 20 % of the collective dose due to dental imaging, over a population of 1540 millions.
Radiology Department, Complutense University, Madrid, Spain. luciano@med.ucm.es
Luciano
L
Gonzalez
Eliseo
E
Vano
Ramon
R
Fernandez
Viviana
V
Ziraldo
Jaime
J
Delgado
Victor
V
Delgado
Javier
J
Moro
Carlos
C
Ubeda
D006801:Humans; D008297:Male; D019047:Phantoms, Imaging; D011786:Quality Control; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D019252:Radiography, Dental, Digital / Q000295:instrumentation / Q000379:methods* / Q000592:standards*; D059629:Signal-To-Noise Ratio