Microcalcifications are tiny spots of calcium deposit that often occur in female breasts. Microcalcifications are common in healthy woman, but they often are an early sign of breast cancer. On a mammogram; the current standard of care for breast screening; calcifications appear as tiny white dots. They may occur scattered throughout the breast or grouped in clusters. Radiologists determine the suspiciousness based upon several factors, including position, frequency, grouping, evolution compared to prior studies and shape. In this paper, we study micro-CT images of biopsy samples containing microcalcifications. The scanner delivers 3D images with a voxel size of 8.66 μm, i.e. ca. 8 times the spatial resolution of a contemporary digital mammogram. We propose an automated binary classification method of the samples, based upon shape analysis of the microcalcifications. The study is performed on a set of 50 benign and 50 malign samples preserved in paraffin. The ground truth of the classification is based upon anapathological investigation of the paraffin blocks. The results show a sensitivity, i.e. the percentage of correctly classified malign samples, of up to 98% with a specificity of 40%.
Adaptive statistical iterative reconstruction (ASiR) is a new reconstruction algorithm used in the field of medical X-ray
imaging. This new reconstruction method combines the idealized system representation, as we know it from the standard
Filtered Back Projection (FBP) algorithm, and the strength of iterative reconstruction by including a noise model in the
reconstruction scheme. It studies how noise propagates through the reconstruction steps, feeds this model back into the
loop and iteratively reduces noise in the reconstructed image without affecting spatial resolution. In this paper the effect
of ASiR on the contrast to noise ratio is studied using the low contrast module of the Catphan phantom. The experiments
were done on a GE LightSpeed VCT system at different voltages and currents. The results show reduced noise and
increased contrast for the ASiR reconstructions compared to the standard FBP method. For the same contrast to noise
ratio the images from ASiR can be obtained using 60% less current, leading to a reduction in dose of the same amount.
Spatial resolution describes the ability to distinguish adjacent objects. It is often used as a measure of the quality of an image. By studying the edge of a cylindrical object a value for the spatial resolution is obtained. However, as a consequence of the polychromatic source used in micro-CT, beam hardening will occur which has the effect of enhancing the edges of the objects in the reconstruction images. These artefacts will have an influence on the resolution measure. In this paper, the spatial resolution in the reconstruction images is determined with and without beam hardening correction. In addition, the effect of the geometric magnification and the dependence on the type of sample material is studied.