No abstract available

[en] Disclosed is a scintillator for a gamma ray camera constituted by a crystal of NaI (Tl) having a surface roughness of less than 400 grit and a thickness of less than approximately 9 mm

[en] A whole body Positron CT has been developed. The system has a gantry consisting of 4 detector-rings and provides 7 slice-images simultaneously. The continuously rotating scan method is employed in this system. Each detector-ring consists of 192 gamma-ray detectors using BGO scintillation crystals (12 x 24 x 24 mm). A dual rectangular photomultiplier tube has been developed to increase the detector packing factor and to improve detector performance. Spatial resolution for reconstructed image is equal to 7.6 mm FWHM at the center of FOV. In a 20 cm-dia. cylindrical phantom, sensitivities are 33.9 kcps/(μCi/cc) and 52.0 kcps/(μCi/cc) in the in-plane and cross-plan, respectively. These include scattered coincidence events. By using the ''projection background cutting method'', scatter coincidence counts are estimated as 21.6% and 23.3% of the total coincidence counts in the in-plane and cross-plane, respectively

[en] We developed automatic production system for short lived radioactive gases (₁₁CO, ₁₁CO², ₁₅O², C₁₅O²) and 18F-labelled FDG. To develop such system is essential for nuclear medicine that uses cyclotrons, because such systems will decrease the exposures of radiations to radiopharmaceutists and deliver them from hard routine work. The principle of production method for such radioactive gases is well known, so we tried to make a fully automatic operation system and to decrease the dimensions of production systems. We realized fully automatic production and very compact production system. This system has been used from autumn in 1981. For ₁₈F-labelled FDG, preparation method is known but some problems that disturb to make automatic operation system are remained. We tried to find a solution that cause to realize the automatic operation

[en] A description and analysis are presented of positron-emission computed tomographs which utilize the continuous rotation scan of a ring detector array. The detectors are arranged in a particular irregularity determined by a computer. The aim of the rotation scan is to exceed the sampling requirement to recover intrinsic detector resolution with high sampling redundancy. It has already been shown that fine and uniform sampling can be achieved with continuous multiple rotation. To obtain an angularly invariant sampling with limited angle (<360⁰) rotation, the angle of rotation must be 360⁰/n where n is an odd integer (>=3), and the detector array should be composed of n identical subarrays arranged in every 360⁰/n. The detectors must also be arranged on a non-circular ring to avoid concentration of sampling points. An example of a detector array for 120⁰ rotation (n=3) shows excellent sampling characteristics. The effect of linear and angular sampling on spatial resolution is discussed taking into account the smoothing effect of data binning. It is shown that the smoothing effect is not appreciable if the Nyquist frequencies for sampling are properly chosen. A rotary positron tomograph, Positologica, which has been developed for brain study, has a circular array of 64 BGO crystals. The spatial resolution is 5.8 mm FWHM at the centre and less than 9 mm FWHM in the field of view. The point spread functions well reflect the results of theoretical analysis. (author)

[en] Highlights: • Perfusion CT using low-dose contrast agent preserved arterial visualization. • Perfusion CT using low-dose contrast agent preserved the tumor detection rate. • Renal perfusion CT may be a substitute for conventional CT. -- Abstract: To compare perfusion computed tomography (CT) with reconstructed image from source data using low-dose contrast agent and conventional 320-row CT for the evaluation of renal tumours.