We, a user group for medical applications of the SPring-8, have proposed the introduction of white X-rays from insertion devices to BMIC (BioMedical Imaging Center) for clinical uses so that enough photon fluxes to a subject is guaranteed. The photon flux, depending on various monochromatizing methods, was compared at the surface of the subject 200 m from a light source.

OBJECTIVES:To correlate the features of magnetic resonance (MR) images of experimentally induced obstructive sialadenitis in rat submandibular glands with the histopathological changes.METHODS:Changes in MR images of ligated and non-ligated rat submandibular glands were compared with the histopathological changes and wet weight ratios. Spin echo T1 weighted images (SE T1WI), fast spin echo T2 weighted images (FSE T2WI), and gradient echo T2 weighted images (GE T2WI) were obtained at 1, 2, 3, 4, 5, 7 and 21 days after duct ligation with a 0.3 T MR imaging system.RESULTS:There was a significant difference (P<0.05) between the signal intensity ratios of both ligated and non-ligated glands on each day, except at 21 days on GE T2WI. On SE T1WI, small interval changes of signal intensity ratios were observed on both glands, whereas there were large interval changes at 1 - 2 days, 4 - 7 days and 21 days after duct ligation with FSE T2WI. These three periods correlated highly with three phases of histopathological changes, swelling of acinar cells at 1 - 2 days, atrophy of acinar cells and increase of duct-like structures at 3 - 7 days, and proliferation of connective tissue at 21 days, and the changes in wet weight ratios. A similar tendency was observed on GE T2WI to FSE T2WI.CONCLUSIONS:As FSE T2WI showed large changes in signal intensity that correlated highly with histopathological three phases, it is recommended as the MR sequence of choice for diagnosing the degree of damage in obstructive sialadenitis.

Three medical application beamlines of the SPring-8 are planned to be installed. The first beamline is a beamline from a bending magnet. The remaining two beamlines are from insertion devices. Medical application user group of SPring-8 recommends that those beamlines should be from a wiggler and undulator. Our proposal is as follows: the first goal of the beamline is to develop a coronary cineangiographic system. Single-energy X-ray exposure with energy above K-edge of iodine (contrast medium) is proposed to reduce exposure dose. X-ray with this energy produces cineangiogram with high contrast. To reduce, furthermore, exposure dose to the patient, 37 keV monochromatic X-ray has been proposed, even though its image contrast might slightly deteriorate. A multipole wiggler should be installed in the medical beamline, mainly because we use nonsymmetric monochromator to obtain wide exposure field. Another beamline should be from an undulator. The first application of this beamline is a divergent and monochromatic X-ray source which is necessary for taking diagnostic images of human subjects. The X-ray source will be generated by fluorescent X-ray. Another application of this beamline will be development of diagnostic imaging system using a expanded X-ray by multi-layer and super mirror. Diagnostic imaging systems to be developed using both beamlines will be: 1. Monochromatic coronary angiography, 2. Monochromatic X-ray CT, based on transmitted, Compton scatter, Thomson scatter, fluorescent, and energy subtraction, 3. Microangiography, 4. Tumor detection imaging, 5. Phase-contrast X-ray imaging whose sensitivity is much higher than that of the absorption-contrast imaging, and so on.

We have developed a monochromatic x-ray CT system which consists of a fluorescent x-ray source generated by synchrotron radiation, a CdTe array detector a rotating table and a computer system. We performed phantom experiments at NE5 station (KEK, Japan) and compared the experimentally obtained CT values with the theoretically calculated values. The measured and theoretically calculated CT values (linear attenuation coefficients) were within 6% agreement over a wide range of iodine concentrations.

We describe a technique of three-dimensional computed tomography (3-D CT) using monochromatic x rays generated by synchrotron radiation, which performs a direct reconstruction of a 3-D volume image of an object from its cone-beam projections. For the development, we propose a practical scanning orbit of the x-ray source to obtain complete 3-D information on an object, and its corresponding 3-D image reconstruction algorithm. The validity and usefulness of the proposed scanning orbit and reconstruction algorithm were confirmed by computer simulation studies. Based on these investigations, we have developed a prototype 3-D monochromatic x-ray CT using synchrotron radiation, which provides exact 3-D reconstruction and material-selective imaging by using the K-edge energy subtraction technique. (C) 1998 society of Photo-Optical Instrumentation Engineers.

From the study of performance of scanning slit X-ray radiography, the following results were obtained. (1) It is confirmed that, by choosing proper width of electronic slit on 2-dimensional detector, effect of scattered radiation can be almost removed. (2) With the narrower incident beam and the narrower electronic slit width, the more the contrast increases. (3)Stripe like artifact appearing on the case of narrow slit width can be removed by interpolation processing. (4) From the PSF (point spread function) calculated by Monte Carlo simulation, scatter rejection performance parameters were calculated.

In diagnostic imaging studies, the energy response of x-ray image sensors, such as newly developed screen/film systems, scintillators, storage phosphors, and CCD sensors is one of the most important characteristics. A monochromatic x-ray source with a wide energy range is necessary to determine the output of the sensor systems as a function of x-ray energy.

誘電型加温装置を用いて患者の深部を加温する場合, 皮下脂肪が過剰に発熱することにより深部に充分な電磁エネルギーを供給することが困難である.このことは, 誘電型加温の加温特性そのものによることが最も大きい原因であるが, しかしそれ以外に実際的な加温において誘電型加温方法が潜在的にもっている深部加温能力を十分に出されていないことによることに起因しているとも考えられる.後者については, 加温条件を最適化することにより誘電型加温方法がもっている潜在的加温能力を充分に発揮させることが可能になると考えられる.そこで, 被加温体を楕円柱とし, それにbolus, overlay bolusを装着したときの発熱分布をコンピュータを用いて解析した.そして, 現在の使用条件における発熱分布と最適化した加温条件における発熱分布を比較した.その結果, bolus, overlay bolusの最適化を行うことにより, 深部に供給できる電磁エネルギーを現在より33%向上できることが示された.

This paper describes an x‐ray K‐edge subtraction television system for noninvasive angiography utilizing synchrotron radiation. The phantom, including contrast material (iodine), is irradiated by monochromatized dual‐energy x‐ray flux, alternately, using a high speed monochromator. The monochromator consists of a silicon crystal plate vibrating at 15 Hz so that the phantom is irradiated by the x‐ray flux of 150 eV above and below the K‐edge photon energy of iodine, 15 times per second. As an x‐ray detector, TV cameras optically coupled to an x‐ray image intensifier are used and the video signal is processed to display the subtraction image of pairs of successive images in real time. This system was fully implemented and moving phantoms were examined. Both the time interval between the energy change and the exposure time of each image has been shortened to 2 ms.

An X-ray K-edge subtraction television system utilizing synchrotron radiation is investigated. The phantom is irradiated by two monochromatized X-ray beams closely bracketing the K-absorption edge of iodine (33.17 keV) alternately, by means of a vibrating single crystal monochromator combined with a white synchrotron X-ray beam. The subtraction of the successive two images produced by these beams results in images that enhance signals arising from attenuation by iodine and suppresses signals by other materials. The prototype system is fully implemented using two kinds of real time image processing subsystems. The results are compared with those obtained by the conventional (nonreal time) processing system.