Medical Image Processing Laboratory (MIP Lab) conducts research on various medical imaging technologies with the main theme of “visualizing invisible information.” In the medical imaging, electromagnetic waves such as X-rays or gamma rays are used to visualize the information such as anatomical structure or function of an internal organ. We have studied semiconductor detectors made of CdTe and CdZnTe to measure X-rays and gamma rays, and developed a prototype of X-ray computed tomography (CT) system and single photon emission CT (SPECT) system. In addition, we developed a photon counting CT (PCCT) system with a CdTe detector, which is a next generation X-ray CT system. The new PCCT can expand the ability of the X-ray CT from an anatomical imaging apparatus to functional imaging apparatus. For the SPECT system, we have developed a new stationary SPECT system with multi-pinhole collimators and multi-detectors, which enables us to observe dynamics of an organ. As well as the development of radiation detectors, we have studied photon transportation methods with a Monte Carlo method and image reconstruction methods. We also studied restoration methods of X-ray images, CT images and optical coherence tomography (OCT) images with a deep learning (convolutional neural network: CNN) method. MIP lab challenges the wide range of themes in the medical imaging field.