New photomultiplier tubes for medical imaging

Recent progress in the development of PMTs (photomultiplier tubes) for medical imaging is reviewed. The use of PMTs in three areas of medical imaging is examined: (1) Anger camera and SPECT (single-photon-emission computed tomography); (2) PET (positron emission tomography); and (3) stimulated luminescence radiography. In SPECT, rotating Anger cameras are most widely used at present, but various systems have been developed. In response to these developments, the quality of PMTs has been continuously improved and adapted to the above applications. In PET, much severer requirements are imposed on PMTs. For high-spatial-resolution PET, the appropriate size and shape would be a detector ring with closely packed, small scintillation crystals. For time-of-flight PET, fast timing and high sensitivity for ultraviolet light are essential. The invention of digital radiography based on an X-ray imaging plate (scanner laser stimulated luminescence) has motivated the development of a PMT with a long sensitive area