Japanese Journal of Radiological Technology

Up to date, Groedel technic is used as one method to eliminate the scattered rays together with Grid technic. But the Groedel technic is regarded as less effective than the Grid technic because of it complexity, enlargement of image and coarse image quality. Recentry, exposure reduction is discussed to the whole radiography regions and making certain results. Here, we report our trial on chest radiography with Groedel technic. By making best use of Groedel technic nature, we succeeded in reducing exposure to 1/3 and gaining better image quality. To compare our new method with conventional Grid technic, we tested enlargement of image penumbra and image quality on MTF. We add that chest radiography with Groedel technic is clinically making pretty good results.

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In recent years, angiographic examinations have been to be indispensable to medical examinations, and the cases of these examinations are increasing every year. We made investigations with a view to following items in abdominal angiographic examinations. 1) Radiographic positioning. 2) Exposure factors. (Tube voltage. Tube current. Exposure time. Grid. Film.) 3) Angiographic table. 4) Exposure field. Compensating filter. 5) Off focus X-rays. 6) The amount of radiation to the patient.

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The amount of high energy electron beams is instable owing to lots of factors. As a matter of course, we should be careful in controling the amount of beams and it is also necessary to improve the beam monitoring apparatuses to make them stable. We have improved a usual monitor and had experiments with it. Here is the report. (1) An ordinary monitor is influenced by humidity, air atmoshere induced noise from an apparatus and so on. We made a new monitor with due regard to these factors. When the count is set to 100 with a usual monitor, the standard dose meter (ionex) indicate is 280R in 16 MeV and the lowest one is 198R. Between standard dose meter (ionex) and usual monitor is 82R. With the trial monitor, the highest integrated dose is 103R and the lowest one is 89R. The difference is only 14R and we are satisfied with the result. We gaine this value after 16 months'trial. (2) The chamber is made air tight and has a double structure with a collection electrode sandwiched between high tension charging electrodes. In this way, we can eliminate the influences of humidity and induced noise from an apparatus itself and we can putup ion collection efficiency without wide the the distance between the electrodes. As for the indicator circuit, we can get an input signal with a big s/n ratio and so we need not use high impedance resistors in the input circuitry. There is little affect from humidity and induced noise, and the circuit is stable. The indicator circuit has a complete electronic system, therefore counting speed is greatly improved and we can measure a large amount of beams in a short time. The trial monitor has four measuring ranges and so measuring is easily done. Our monitor has a circuit tester, too, and we can test the measuring circuit on occasion.

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Arthrography of the knee joint has been steadily improved since Andren and Wehrin reported "double contrast-horizontal beem method" in 1960. But its object is only to observe medial and lateral meniscus. In this paper, we report our new method to reveal all components of the knee joint such as menisci, articular cartilage, synovial membrane and ligaments. By this method, arthrography of the knee joint is applied to not only menicus injury but also rheumatoid arthritis, osteoarthritis and other disorders of the knee joint.

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