The exact position of coronary artery (CA) stenosis cannot be determined from SPECT images and diagnostic procedures require high level of experience from the physician. In order to assist the physician's understanding of such images, we propose a new system, which can display clearly the relationships between the CA and the cardiac wall. We achieve this result by superimposing the 3-dimensional coronary artery model on the observed left ventricle (LV) shape. However, there are a number of problems, when superimposing a 3D CA model on the 3D LV shape. The actual shape of the heart is notably dependant on the subject and it is different from anatomical model shapes, especially in the ischemic heart. That is why we have developed an algorithm to estimate the ischemic wall and to superimpose the CA model on the LV shape. We use ellipsoid models, which fit on the CA model and on the observed heart wall respectively. To evaluate this algorithm, we introduce a measure for the average distance between the two models, and apply actual clinical data. The obtained results from these experiments could be considered promising.

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We describe a system of fluorescent X-ray computed tomography using synchrotron radiation (SR-FXCT) to image nonradioactive contrast materials. The system operates on the basis of computed tomography (CT) scanned by the pencil beam. In the previous experiment, we have imaged an acrylic cylindrical phantom with cross-shaped channel, filled with a diluted iodine-based tracer material of 200μg/ml. This research is aimed to improve image quality, to select the optimum energy of the incident X-ray, to confirm quantitative evaluation of the image, and to demonstrate FXCT image for living body. First, we simulated output energy profile by the Monte Carlo simulation and confirmed to predetermine the incident X-ray energy at 37keV, in order to separate the fluorescent photons from background scattering components. Next, the imaging experiment was performed by using conventional CT algorithm under the optimum parameter at the Tristan Accumulation Ring, KEK, Japan. An acrylic phantom containing five paraxial channels of 5 and 4mm in diameter, could be imaged; where each channel was respectively filled with diluted iodine-based contrast materials of 50, 100, 200 and 500μg/ml. From the reconstructed image, we confirmed quantitativity in the FXCT image. Finally, a rat's brain was imaged in vitro by FXCT and monochromatic transmission CT. The comparison between these results showed that the iodine-rich region in the FXCT image corresponded with that in the monochromatic transmission CT image.

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By using the planetary, screw disc and vibration type ball mills, mechanically activated states of Ti-C powders formed in milling were investigated with the change of their reaction temperature. The temperature decreased with increasing milling time, and its relation is characteristic of the milling methods. Especially, in case of the vibration mill, there is clear indication that the reaction temperature of milled powder was saturated at a constant value as the lapse of the milling time, and also the size of balls charged in mill influenced markedly to the reaction temperature.

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Ischemic heart disease is closely related to stenosis on the coronary artery (CA), and the volume change of the left ventricle (LV) in a cardiac cycle is an important index for the evaluation of cardiac function. Coronary angiograms are usually used to identify stenotic position and its level, in clinical practice. However, a coronary angiogram also has information on heart motion in its time-series record. Usually, physicians only feel an abnormal motion from his empirical model and perform another inspection to confirm it. In this paper, we developed a method to estimate deformation and motion of the left ventricle by ellipsoidal fitting to three-dimensional shapes of the CA from time-series images of a biplanar CA angiogram. We had demonstrated this procedure against a clinical CA angiogram.

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In order to obtain spherical fine powders, a new high-pressure water atomization method using swirl water jet was developed. In this paper the effects of jet swirl angle(ω)upon the properties of powders were investigated. Cu-10 mass%Sn alloy was atomized by this method at the constant water pressure of 83.3MPa and constant metal orifice diameter of 4mm, while ω was varied from 0 to 0.18rad.
Median diameter of the powder by the laser diffraction method(D₅₀)decreased from 12.5μm to 7.5μm with increasing w, and this corresponded to Fisher average diameter(D_FS)at about ω=0.18 rad. The apparent and tap density of the powder increased about 1 and 1.5Mg/m³ respectively, and the particle shape observed by SEM became spherical with increasing ω.

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The three manufacture engineerings on copper and copper based alloyed powders for powder metallurgy have been developed. The powders manufactured by these methods were as follows.
1) The partially alloyed copper powder can be manufactured by only the simple heat treatment after mixing. And this powder has the properties as nearly good in compactibility and sinterability as mixed powders and less in segregation.
2) By applying the stable condition of the water jet, Cu-Sn, Cu-Zn, Cu-Co and Cu-Sn-Pb-Zn alloys were atomized and the obtained powders have compactibility of 1.5-2.0 times higher than that of powders produced under the conventional condition.
3) The spherical finer powder was manufactured by the newly developed high-pressure water atomization method using swirl water jet. Cu-Sn alloy was atomized by this method. The median diameter of this powder decreased from 12.5μm to 7.5μm with increasing swirl degree.

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Phase-contrast x-ray imaging with x-ray interferometer can depict the minute difference within the biological object, and its sensitivity is about 1000 times higher than that of absorption- contrast method. For biomedical use of this technique, a large monolithic x-ray interferometer and 2 crystal interferometer having a field of view with 25 mm x 25 mm is being developed.
Phase-contrast x-ray CT could reveal detail structures within tumor and surrounded tissue, and the vessel imaging of rat liver is also possible using physiological saline at 17.7 keV x-ray energy. Recently, human breast tissues were imaged at 35 keV and the contrast of image was much better than usual absorption contrast xray image obtained at 17.7 keV energy.

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Extensive researches in the past on methods of producing metallic powder by atomizing the molten metals with air or water jets have resulted in the industrialization of a number of these methods. However, no intensive research has yet been accomplished on the centrifugal method of atomizing the molten metals by revolving a rotor at an enormous speed, although the principle had been generally known. The research under discussion undertakes to probe the atomizing effects involved in the centrifugal atomizing process and thereby to bare the basic technicalities involved in the process. Many problems yet need to be solved before this process can be industrialized, but it has been confirmed that this process is highly promising for industrialization.
The principal dimensions of the rotor used in this experiment were as follows : outermost periphery of rotor 65mm, conical angle of inner surface 70°and maximum speed of rotor 20, 000 rpm. The nozzles on the underside of the melting pot were given five diameters of 0.8mm, 1.0mm, 1.2mm, 1.4mm and 1.6mm.
The predominant results obtained in the experiment are as follows :
(1) Distribution of the particle size is adjustable freely by changing the number of revolutions.
(2) The grain diameter of the metallic powder obtained is considerably uniform as compared with that prepared, by the method of utilizing gas ; that is, the distribution of particle size makes a sharp curve.
(3) Since no gaseous matter is employed in the atomizing process, the recovery of the obtained powder is very easily done.

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Much of coarse aluminium powder for thermit reaction has been produced by the cross jet method. But the fine powder is less produced thereby. Recently, demands for fine aluminium powder are increasing gradually and it is urgently requested that vertical atomization for molten aluminium is developed and brought to industrialization, because the vertical atomization is said to be preferable for manufacturing fine metal powder.
This experiment was carried out to investigate the fundamental behavior of vertical atomization, comparing it with the conventional cross jet method. The results derived from this experiment are as follows.
1) It is fully possible that the minus 200mesh fine aluminium powder is produced more than 50 percent of the whole atomized powder by vertical atomization. On the other hand it is not easy to take out minus 200mesh fine powder more than 30 percent by cross jet mothod.
2) In order to obtain a given distribution, the vertical atomization requires much lower air pressure than the cross jet method.
3) In vertical atomizing the air jet forms a closed air curtain beneath the nozzle tip and a back pressure takes place. It prevents the settling of the molten aluminium. Then the unit manufacturing capacity of the vertical atomization is 50-60 percent of that of the cross jet method.
4) The disintegration by the cross jet is almost impossible, when sprayed by air compressed at a pressure lower than 2kg/cm².
5) In the case of the vertical atomization by using a small bore strainer, the molten aluminium is apt to solidify in the strainer to the cooling by the air jet.

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加速器施設や核医学施設、福島第一原発の建屋外などにはガンマ線の高線量場が存在する。これらの場所においても使用可能な広視野ガンマ線イメージンカメラがあれば効率的にホットスポットを確認・発見することができる。そこで今回、全方向イメージングが可能なコンプトンカメラの研究・開発を行った。高線量照射実験の結果、1 mSv/h(検出器設置位置)でのスペクトル取得及びイメージングに成功した。本発表では検出器の開発や高線量照射実験・実証試験の測定結果について報告をする。

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Some basic properties of CrSi₂ as a refractory hard material have been investigated. CrSi₂ powder was prepared by arc melting of pure chromium and silicon mixture in an argon atmosphere and subsequently crushed by ball mill. This powder was then hot-pressed in vaccum.
The specimens obtained were subjected to various tests, the results of which are summarized as follows.
1 The optimum temperature in hot-pressing of CrSi₂ was 1350°C. The density attained 97.0% of the theoretical value.
2 Corrosion resistances to three kinds of dilute acids were superior to any other Disilisides which we had studied.
3 The oxidation resistance at 1200°C was 0.0011g/cm²/day.
4 Electrical resistance at room temperature was 646×10^-6Ω-cm, 1900×10^-6Ω-cm at 800°C.
5 Thermo electromotive force at room and high temperature was 30 to 60 times higher than that of MoSi2 and TiSi₂.
6 In general, the hardness in hot state decreases with rising temperature. For instance, it was 280 at 800°C.
7 Modulus of rupture at 800°C was 21.3kg/mm².
8 The thermal shock resistance of CrSi₂ was poor.

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Atomization appeared to be the best means of obtaining pre-alloved powders without applying a limitation on composition. However, difficulty in the control of particle shapes has restricted the utilization of pre-alloyed powders produced by that process. The investigation has been therefore made on the water atomization of copper alloys, and subsequently the physical properties of the powders and of their pressed compacts were examined.
The results were summarised as follows : -
(1) Molten copper alloys atomized with water become the irregular particles, and this leads to be low apparent density.
(2) To facilitate to produce compacts of high green strength, it may be necessary for atomized bronze and brass powders to be annealed at an adequate temperature.
(3) High rate of cooling velocity developes quenched phase structure in alloys, particularly with alloys such as bronze and Kelmet that has a considerable gap between the liquidus and the solidus. Particles atomized with water show fine quenched phase structures, in comparison with the particles atomized with gas.

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今回、今まで以上に安価、かつ高感度に全方向のガンマ線イメージングできるコンプトンカメラの開発を行った。特徴としては、正四面体の頂点に結晶を配置することで、最小数で全方向をイメージングすることが出来る。また、結晶間を近づけることにより、検出器の位置で0.1 μSv/hになる場所に線源を置いた場合、10秒程度で特定できるほどの高感度を達成した。本発表では、検出器の開発状況および測定結果について報告する。

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Mechanical alloying of Titanium, Molybdenum, Nickel and graphite powders was performed using a vibrational ball-mill. Mechanical alloying process of cermet powder was studied by X-ray diffraction, electron probe micro analysis (EPMA) and scanning electron microscopy.
Results from X-ray diffraction and EPMA suggested the synthesis of TiC was carried out for about 50 hours and the addition of Ni assisted this synthesis. The difference of mechanical alloying atmosphere had an effect on particle size of TiC after sintered. Mechanical alloyed Ti-C-20mass%Ni-10mass%Mo was able to sinter at low temperature and had a minute structure.

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The slip casting of Cu and SUS316L fine powders was made by using the triethanol alginate as the binder material. The slip containing 15.4-18.2mass% water and 0.15-0.18 ?? ass% triethanol alginate had the good flowability. The green relative density of Cu and SUS316L were 52 and 51%. By sintering at 970°C in H₂ gas for lhr, Cu green bodys were densified to 96% and over. By sintering at 1300°C in vaccum for 1hr, SUS316L green bodys were densified 96% and over.Speci.ens sintered at 1300°C showed the ultimate tensile strength of 500MPa and the elongation of 35%.

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