Image Quality Comparison between Synthetic 2D Mammograms Obtained with 15° and 40° X-ray Tube Angular Range: A Quantitative Phantom Study

In this work we present an image quality comparison between synthesized mammograms (SMs) obtained from Digital Breast Tomosynthesis (DBT) acquisitions with 15 degrees (SM15) and 40 degrees (SM40) X-ray tube angular range. In fact, since wide-angle DBT is characterized by a better spatial resolution in depth but also by worse performance in detecting microcalcifications than narrow-angle DBT, an objective image quality analysis of SM images could be of pratical interest. Four phantoms were employed in this study and their images were acquired using an Amulet Innovality mammographic device. The image quality comparison was conducted by evaluating spatial resolution, contrast and noise properties of the images. Our results show that SM40 images are characterized by better spatial resolution performance than SMI5 in terms of Modulation Transfer Function but also by worse performance in the detection of low-contrast details. In fact, higher contrast-tonoise ratio values were obtained with SM15 than with SM40. Noise properties of the images were also investigated through the Noise Power Spectrum (NPS) calculation: no differences in NPS shapes were found in both modalities, while noise magnitude results significantly different. In addition, Signal-to-Noise Ratio (SNR) spatial distribution evaluation was assessed by computing SNR maps, in which different pattern were observed.