Radiographic technique factors and imaging performance in digital mammography

Abstract

Simulated mass lesions were superimposed onto an anthropomorphic breast phantom and x-rayed using a small field of view digital mammography system. Digital radiographs were acquired at a range of x-ray tube potential (constant detector exposure), and a range of x-ray tube current-time product values (constant x-ray tube potential). Twelve readers assessed the probability of a simulated mass being present in specified regions of interest, with the resultant data used to determine the area under the receiver operating characteristic curve (Az). The mean Az value obtained at 28 kVp/72 mAs was 0.69. At the same x-ray tube potential, the Az score fell to 0.63 (p less than 0.05) at 32 mAs, whereas the mean Az score of 0.71 was not significantly different for the image acquired at 144 mAs. At a constant detector exposure, reducing the x-ray tube potential to 22 kVp (320 mAs) resulted in a mean Az value of 0.72, whereas increasing the x-ray tube potential to 34 kVp (28 mAs) resulted in a mean Az value of 0.69. For the detection of simulated mass lesions in an anthropomorphic breast phantom, changing the kVP at a constant detector exposure had no significant effect on imaging performance, whereas halving the mAs at a constant kVp reduced the Az value by approximately 10%.