Radial Digital Breast Tomosynthesis Using a Shift-and-Add Algorithm

With the advent of flat-panel detectors capable of high-speed data communication, conventional geometric tomography is once again attracting attention in the form of tomosynthesis. In this study, the use of radial tomosynthesis for tomographic image reconstruction of breast cancer specimens from different directions using the shift-and-add algorithm, the simplest image reconstruction method used in tomosynthesis was validated. To simplify image processing, synchrotron X-rays that provide a parallel X-ray beam were used. The X-ray energy was 17.5 keV. The range of rotation of the object corresponding to the swing angle of the X-ray tube was ±40°, with the object rotated in 1° increments to scan a total of 81 projection images. From these projection images, 41 images were extracted with a tomographic angle of ±20° with respect to an arbitrary fulcrum plane, and the tomographic planes were rotated radially to reconstruct varying tomographic images. Unlike multiplanar reconstruction, which has a high degree of freedom of choice of tomographic planes, in radial tomosynthesis, the variation in orientation of the tomographic planes is limited to a single axis. However, this study demonstrated that this method not only possesses sufficiently high spatial resolution to meet the requirements of breast cancer diagnosis for high-resolution images, but also provides tomographic images that can be observed from different directions.