I have been engaged in the field of radiation measurement, including in applications for environmental radiation monitoring, especially for Cs-137, and medical applications such as positron emission tomography and single photon emission CT. In those applications, I have focused especially on developing three-dimensional image reconstruction algorithms and electronics such as integrated circuits for high-speed and low-noise readout. By developing advanced measurement technologies that have realized heavy demands for physics experiments, I aim to further develop not only physics experiments, but also a three-dimensional imaging system which can achieve high sensitivity and high resolution for cancer stem cell research.