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Specifications were developed for a PET (positron emission tomography) system that emphasizes high-count-rate performance and is specifically designed for the estimation of myocardial perfusion using oxygen-15 water and dynamic imaging protocols. The seven-slice CsF detector array is a one-on-one configuration, and has a reconstructed FOV (field of view) of 52 cm and an axial FOV of 10.7 cm. Wobble and axial translation are used. The gantry and associated electronics were interfaced to a new computer system, data collection and image reconstruction software was developed and the performance of the system was characterized with phantom, animal, and human studies. The system sensitivity is 136000 cts/s/ mu Ci/cm/sup 3/ and the reconstructed resolution is better than 9 mm. Imaging a 20-cm uniform phantom with 4.3 mu Ci/cm/sup 3/, the system collects a total rate of 1.57 Mcts/s with a loss fraction of 0.72 and a ratio of randoms/trues of 0.64. >

The physical characteristics and some imaging capabilities of Super PETT I, a positron emission tomograph utilizing time-of-flight (TOF) in its image reconstruction process were assessed experimentally by means of measurements carried out in phantoms and clinical imaging studies. The performance characteristics assessed included sensitivity, spatial resolution, image improvements resulting from time-of-flight information utilization, system dead time, and linearity. The clinical examples included imaging of the brain, the heart, the liver, and a demonstration of Super PETT I's capability of achieving cardiac gating.

The operation of PETT IV, a positron emission transverse tomograph capable of multislice imaging, relies on an electronic design which was developed for that system. The functions performed by this system include operation of the scintillation detectors, ?-ray positioning circuitry, data collection logic, and computer interfacing. Design considerations and performance characteristics of PETT IV and this circuitry are presented here.

We designed and built a positron emission transverse tomograph (PETT VI), designed specifically for fast dynamic studies in the human brain, and for cardiac studies in experimental animals. The scintillation detectors incorporated into this device are fitted with cesium fluoride crystals. Cesium fluoride was selected for this purpose because its short fluorescence decay allows the use of a short coincidence resolving time with a concomitant reduction of unwanted random coincidences. PETT VI utilizes four rings of 72 detectors simultaneously yielding seven tomographic sections. The system can be operated in either a low or high resolution mode with intrinsic geometrical resolutions in the plane of section of 7.1 to 11.7 mm full width at half maximum (FWHM), for a slice thickness with a resolution at the center of 13.9 mm FWHM. The maximum sensitivity of the system for seven slices in the low resolution mode is 322,000 cps/microCi/cc in a 20 cm diameter phantom. The contribution of random coincidences before subtraction in PETT VI was found to be approximately 14% of the counts in the phantom image with a source of approximately 3.5 mCi of a positron emitting radionuclide dispersed in a 20 cm diameter tissue equivalent phantom with a concentration of 1 microCi/cc. The short coincidence resolving time of the system permits rapid data acquisition for attenuation corrections and clinical dynamic studies with data acquisition times of less than a minute.

Imaging of the brain by positron emission tomography can be optimized for sensitivity by dedicating the design of the tomograph to this application. We have designed a multislice positron emission tomograph (PETT V) for imaging the human brain and the whole body of small experimental animals. The detector system of PETT V consists of a circular array of 48 NaI(Tl) scintillation detectors, each fitted with two photomultiplier tubes, with one dimensional positioning capability. Suitable sampling is achieved by rotation of the circular array of detectors and by a wobbling motion of the detector circle. The proposed system is capable of providing seven slices simultaneously, with a spatial resolution in the plane of the slice from 7 to 15 mm and with slice thicknesses of 7 and 14 mm. The minimum scanning time is 1 sec. The estimated overall sensitivity of PETT V is 350,000 counts/sec/mCi in a 20 cm diameter phantom for a resolution of approximately 1.5 x 1.5 cm. The system is under construction.

We designed, built, and tested a positron emission tomograph (PETT IV) capable of providing seven slices of the human body simultaneously. PETT IV utilizes a moving hexagonal array of 48 scintillation detectors placed around the subject. Each detector consists of a cylindrical activated sodium iodide crystal optically coupled to two photomultiplier tubes. The multislice capability is achieved by comparing the light outputs of the two photomultiplier tubes in each detector. The images are displayed either as transverse or as longitudinal tomographic sections. This system provides high sensitivity and resolution, and permits rapid and accurate three-dimensional imaging of the head and body.

A simple low-volume (3 mL) target has been constructed for the production of 18F via the proton irradiation of 18O enriched water. The target is constructed of copper with the water cavity electroplated with nickel. This target routinely produces more than a curie of 18F (as [18F]fluoride) suitable for radiopharmaceutical syntheses.

PETT VI is a circular ring, multislice positron emission tomograph designed for small field studies. Features such as wobble and rotate motions, bimodal resolution, cesium flouride scintillators, fast timing circuits and dual buffer histogram memories allow a flexible data acquisition environment. Efficient modularized software concepts are implemented to facilitate concurrent tasks of data acquisition, processing and display. The ability to effectively manage high count rate situations and collect continuous time frames makes PETT VI ideally suited for dynamic studies.