Abstract
We propose a new mammography system using a cadmium telluride (CdTe) photon-counting detector for exposure dose
reduction. In contrast to conventional mammography, this system uses high-energy X-rays. This study evaluates the
usefulness of this system in terms of the absorbed dose distribution and contrast-to-noise ratio (CNR) at acrylic step using
a Monte Carlo simulation. In addition, we created a prototype system that uses a CdTe detector and automatic movement
stage. For various conditions, we measured the properties and evaluated the quality of images produced by the system. The
simulation result for a tube voltage of 40 kV and tungsten/barium (W/Ba) as a target/filter shows that the surface dose was
reduced more than 60% compared to that under conventional conditions. The CNR of our proposal system also became
higher than that under conventional conditions. The point at which the CNRs coincide for 4 cm polymethyl methacrylate
(PMMA) at the 2-mm-thick step corresponds to a dose reduction of 30%, and these differences increased with increasing
phantom thickness. To improve the image quality, we determined the problematic aspects of the scanning system. The
results of this study indicate that, by using a higher X-ray energy than in conventional mammography, it is possible to
obtain a significant exposure dose reduction without loss of image quality. Further, the image quality of the prototype
system can be improved by optimizing the balance between the shift-and-add operation and the output of the X-ray tube. In
future work, we will further examine these improvement points.
