[en] A small computer program for processing a microdosimetry single event energy deposition spectrum is presented. The program can perform smoothing of a spectrum and present a comparison of the smoothed and unsmoothed spectrum in order to detect distortions introduced by excessively rough smoothing. To increase the resolution of the spectrum and to reduce the influence of the uncertainty in the zero point setting of the multichannel analyzer, spectra are usually measured with different gain settings and are thereafter overlapped into one spectrum. The computer can perform such an overlapping and make a chi-square-analysis of the overlapping region. Such an analysis may reveal unsatisfactory experimental conditions, such as drifts in the gain between the two measurements, pile up effects or an unproper zero point setting of the multichannel analyzer. A method of dealing with the last mentioned problem is also presented. The program was written for a Nuclear Data computer (ND 812) with a memory of 12 k but it should be easy to apply it to other computers. (author)

[en] The positron camera here discussed has been used clinically in Sweden since 1978, and has so far satisfied all the technical demands made. A 1 cm thick horizontal slice of a patients skull can be examined at any time; the processing of the output data to form a picture takes about six minutes. Improvements to be introduced are the use of a more efficient detecting material, bismuth germanate (BGO), and more rings of detectors. A new camera, to be ready a year from now, will have four rings, each of 96 BGO detectors. Complete pictures at the rate of five per second will be produced, so that a dynamic event in the object under examination can be followed. (G.P.)

[en] Fifteen patients with 21 subdural effusions were investigated both with transmission computer assisted tomography (CAT) and positron emission tomography (PET). The tracer in the emission studies was ⁶⁸Ga-EDTA. Twelve lesions were visualized both with CAT and PET. Five lesions that were negative or doubtful on CAT were visualized with PET, whereas four lesions negative or doubtful on PET were demonstrated by CAT. The two methods complement each other due to the fact that they are based on different mechanisms: CAT mainly on attenuation of the fluid collection. PET on isotope accumulation, particularly in the hematoma membranes

[en] The region around the eta-carbides M₆C and M₁₂C in the quaternary system Fe-W-C-Cr at 1250⁰C has been determined by metallography, X-ray diffraction and electron microprobe analysis. Isothermal sections of the quaternary system at levels of 2,4,6,8,10,15,20 Cr (at.%) have been constructed. The space configuration of the quaternary system is discussed. The lattice parameter and microhardness of the two eta-carbides at different chromium levels have been measured. The intermediate phase in the binary subsystems Cr-C and Fe-Cr have been synthesized. (Auth.)

[en] A modified routine for computer tomography of children, avoiding general anesthesia is discussed. The patients were sedated and examined in a supporting plastic cradle. Radiation doses to various parts of the body were measured during the scanning and the results confirm that the dose levels are within generally accepted limits. (Auth.)

[en] The radiation dose from the first generation EMI scanner has been analysed, including the variation of the dose perpendicular to the section, the dose dependence of the size and collimation of the beam, and the fraction of radiation passing the patient and utilized for information. The possible dose in case of malfunctions of the scanner was also measured. (Auth.)

[en] Some examples of recent development of the synthesis of compounds labelled with short-lived β⁺-emitting radionuclides will be discussed with an emphasis on the importance of time in selecting a synthetic strategy. Furthermore the use of such labelled compounds to monitor certain processes in areas within the field of analytical chemistry and in various applications in drug development will be presented. (au)

[en] The homogeneity regions of the two eta-carbides, (FeW)₆C and (FeW)₁₂C, in the ternary system Fe-W-C at 1250⁰C have been determined by metallography, X-ray diffraction and electron microprobe analysis. The occurrence of the intermediate phases in the binary subsystems Fe-W and W-C at 1250⁰C has been studied. The microhardness of the intermediate phases in the ternary system has been determined. The isothermal section of the system Fe-W-C at 1250⁰C around the eta-carbides has been constructed. (Auth.)

[en] The technique of positron emission tomography (PET) is described. PET is an in vivo imaging and quantitative technique which allows the visualization of various functional and biochemical parameters. PET is a tracer technique in which bioactive tracer substances are labelled with short-lived positron emitting radionuclides. The most important of these are ¹⁵O, ¹³N, ¹¹C and ¹⁸F with decay times ranging from 2 min to 2 h. The radiolabelled substance is injected intravenously and the distribution, uptake and binding are registered externally with the PET camera using of the order of 4000 small detectors. The camera produces simultaneously 15 tomographic slices in which the absolute concentration of the tracer substance can be measured. Using a dynamic imaging sequence starting after the injection of the tracer, the dynamics of the tracer uptake is recorded and can be used to deduce functional parameters, such as perfusion flow, tracer distribution, binding to receptor or enzyme systems, etc. depending on the choice of tracer substance. The great versatility of PET and its potential of direct noninvasive study of tumor function will make it a very important clinical and research tool in oncology. With the choice of substances selective for a certain aspect of a tumor's biochemistry the potential opens for a better diagnosis, improved differential diagnosis and, especially with the use of metabolic tracers, an improved possibility to evaluate the response to treatment. (orig.)

[en] A program for two-dimensional analysis of γ-γ coincidence matrices is described. The program is tailored to the Digital Equipment VT340 colour graphic terminal and written in VAX Fortran. The program provides viewing of the matrix as well as projections in both energy coordinates, determination of centroids and volumes of peaks, full two-dimensional Gauss fits to a maximum of five peaks in an arbitrarily shaped area of the matrix, etc. (orig.)