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[en] The principles underlying emission tomographic techniques are discussed, concentrating on the single photon emission technique. The data acquisition systems and the acquisition parameters of matrix size, number of projections and time per projection are discussed. The spatial resolution and noise sensitivity are also considered. (UK)

[en] The operation of an Auger gamma camera is described. Particular attention is paid to removing the distortions in the resulting images which result from non-uniformity in the response of the scintillation crystal/photomultiplier tube combination. (UK)

[en] The authors are developing a small gamma camera for scintimammography with Tc^99m (140 keV). The camera is based on coupling wavelength-shifting fibers (WSF) to the surface of an inorganic scintillation crystal--CsI(Na)--in order to obtain information about the position of interaction of the gamma rays. They have performed experimental measurements on the light output of 1 mm round multi-clad WSFs coupled to two CsI(Na) slabs, 3 and 5 mm thick. The results show a mean of 3.8 photoelectrons per gamma ray interaction of Co⁵⁷ 122 keV, with a mean of 1 photoelectron at the fiber located nearest the collimated beam of gamma rays, for the 3 mm thick crystal. Simulations based on the single electron response of photomultiplier tubes show that a 1.7 mm FWHM spatial resolution can be achieved with this camera design. The camera can be shaped to suit any application, it is compact and has low cost, which, together with its predicted performance in terms of spatial resolution, makes this concept very promising as a small gamma camera for 140 keV

[en] Single photon computed emission tomography (SPECT) offers additional clinical data, not available by any other techniques. Whilst difficulties with the design of the ideal instrumentation persist, and problems with the accurate reconstruction of tomograms require more elaborate algorithms, its future as a clinical tool appears promising. (orig.)

[en] An original approach to the measurement of bone turnover is presented. With SPECT, the authors have measured in pgr/ml, the uptake of MDP by the skull in man. The Cleon 710 scanner, ring phantoms and bone biopsies were used for ultimate in vivo/in vitro count recovery correlation and calibration. A normal range for 24 patients was found: 8.5 to 19.5 pgr/ml with a mean of 14. For patients with bony metastases (12), the values were: 22.5 to 50, mean of 30. For 5 patients with osteomalacia, the values were 46 to 68, mean of 62: for 12 patients with hyperparathyroidism, the values were 37 to 48.5, mean of 43. In 3 patients with Pagets disease, the values were 58.5 to 75, with a mean of 65. In 76 patients with metastatic disease to bone, the conventional wholebody bone scan was investigated against the following: 24h wholebody retention of MDP (WBR), skull uptake as described and GFR by Cr-51-DTPA. There is a correlation between GFR and WBR - r=0.67. There is a lesser correlation between GFR and skull uptake - r=0.3. There is no correlation between skull uptake and WBR - r=0.1. The comparison of skull uptake data with normal whole body bone scans leads to a significant proportion of cancer patients with positive skull uptake data. Monostotic disease (especially if metabolic in nature) expresses itself by abnormal skull uptake even if the clinical site of abnormality lies outside the skull. This new technique is ideal as a tool to investigate phosphonate concentration in bone. With it, the authors have shown the effect of specific activity of label on skull uptake, which increases as the specific activity of labelled MDP decreases

[en] We have evaluated the R5900-M16 multi-anode photomultiplier tube from Hamamatsu. Three tubes were tested for their uniformity of collection of photo-electrons by the dynode structure and for their uniformity of gain across the active area. Variations of less than 10% in two tubes and 30% in the third one were obtained. The cross-talk between closest neighbour pixels was found to be ∼1%

[en] Collimation of gamma-rays based on Compton scatter could provide in principle high resolution and high sensitivity, thus becoming an advantageous method for the imaging of radioisotopes of clinical interest. A small laboratory prototype of a Compton camera is being constructed in order to initiate studies aimed at assessing the feasibility of Compton imaging of positron emitters. The design of the camera is based on the use of a silicon collimator consisting of a stack of double-sided, AC-coupled microstrip detectors (area 6x6 cm², 500 μm thickness, 128 channels/side). Two APV6 chips are employed for signal readout on opposite planes of each detector. This work presents the first results on the noise performance of the silicon strip detectors. Measurements of the electrical characteristics of the detector are also reported. On the basis of the measured noise, an angular resolution of approximately 5 deg. is predicted for the Compton collimator

[en] A new approach to the radionuclide imaging of the lungs with ¹³³Xe and ⁹⁹Tcsup(m) is illustrated in this paper, describing four patients who were subjected to section scanning of the chest in addition to conventional planar imaging. The significance of this new method in the investigation of patients suspected of having pulmonary embolism is discussed. The main advantages of the new approach include increased information with depth, clearer definition of the mediastinal space, and the detection in some instances of new lesions not seen by conventional means. (author)

No abstract available