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An ACR mammography phantom and three different Contrast Detail (CD) phantoms were used in experiments. Each phantom is 5cm in thickness and fabricated with materials simulating 50% glandular tissue and 50% adipose tissue. The phantoms were imaged by 59kV and 89kV with varying levels of external filtrations. The x-ray exposure was adjusted so that the average glandular dose was consistently to be 1.3 mGy throughout the imaging. A noise reduction algorithm was applied to the images. The algorithm being evaluated is a state-of-the-art self-supervised single image denoising approach that can prioritize the preservation of fine-grained image structures while performing noise removal. The contrast-to-noise (CNR) ratio was measured to conduct objective analysis. Additionally, an observer performance study was conducted in which observers were shown the images from each phantom in a randomized order before and after the denoising algorithm was applied. The observers rated the detectability of each image by identifying the minimum perceptible feature. The results indicate some improvement from the objective studies; however, in the subjective observer studies, no improvement was observed in the detectability of the ACR images, and limited improvement was observed in the detectability of the CD phantom images. |
