RADIATION DETECTOR DEVELOPMENTS IN MEDICAL APPLICATIONS: INORGANIC SCINTILLATORS IN POSITRON EMISSION TOMOGRAPHY

摘要

In recent years, a number of new gamma-ray scintillators are commercially available. These scintillators are either derived from known scintillators, e.g. Lu_(1-x)Y_xAlO_3: Ce (LuYAP) from LuAlO_3:Ce and Lu_(2(1-x))Y_(2x)SiO_5:Ce (LYSO) from Lu_2SiO_5:Ce or are the result of new discoveries, e.g. LaOl_3:Ce and LaBr_3:Ce. The first two materials are primarily of interest because of the relatively high detection efficiency and fast response; LYSO has found application in time-of-flight (TOF) positron-emission tomography (TOF PET) and the LuYAP-LYSO combination is used in small-animal PET. The halide scintillators have an excellent energy resolution of ～3% at 662 keV and they have a relatively high light yield. LaBr_3:Ce is being studied for application in TOF PET. At the same time, the search for and research on new scintillator materials are going on. For example, LuI_3:Ce is a new material with a very high light yield (～90 000 photons MeV~(-1)). Other examples of new materials are (C_6H_(13)NH_3)_2PbI_4 and (C_3H_7NH_3)_2PbBr_4, organic-inorganic hybrid compounds, of which the former has a very fast sub-nanosecond response. The new scintillators show great promise for new developments in medical applications, in particular, for PET systems.