Instrumentation for positron emission tomography: Tomographs and data processing and display systems

Abstract

The field of positron emission tomography (PET) has evolved over the past 10 to 15 years from a basic research endeavor to a field in which both research and clinical studies are performed at over 100 institutions and medical facilities throughout the world. Most centers now use tomographs supplied by commercial vendors and operate data analysis systems employing identical software packages. PET scanners have advanced from prototypes assembled more than 15 years ago that imaged a single slice with 32 detectors at a resolution of greater than 2.0 cm full-width-at-half-maximum (FWHM), to current state-of-the-art instruments that simultaneously image as many as 47 slices using nearly 10,000 detector crystals at resolutions of less than 5 mm FWHM. In addition, specialized research instruments have been developed that have in-plane image resolution of approximately 2.5 mm FWHM. Other PET instrumentation advances include the development of detector block designs with multiple crystals per photomultiplier tube, continuous large position-sensing detectors, and the use of new detector materials having properties particularly suited for PET imaging. Image display and analysis systems have also advanced considerably over this time period. Early scanners typically used analysis stations with dedicated displays of only approximately 256 x 256 pixels and minimal internal processing capabilities. Current systems now offer displays with more than a megabyte (1,024 x 1,024) of image memory and have considerable internal processing capability. Further improvements in the ability to efficiently handle the massive volumes of data generated by the latest generation of scanners in increasingly sophisticated manners are crucial to the continued advancement of the PET field.