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Article type: Cover
1992 Volume 48 Issue 4 Pages
Cover13-
Published: April 01, 1992
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Article type: Index
1992 Volume 48 Issue 4 Pages
Toc13-
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Article type: Index
1992 Volume 48 Issue 4 Pages
Toc14-
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
i-ii
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
ii-
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MAKOTO INOUE, MASAKATSU HATAGAWA, SHINICHI WATANABE, MITSUJI HIGASHIDA
Article type: Article
1992 Volume 48 Issue 4 Pages
611-615
Published: April 01, 1992
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The Fourier transformation of line spread function obtained from slit image is generally used for modulatry transfer function (MTF) measurements. However, the square wave chart method (contrast method) is better than the slit method for ordinary clinical applications. A new device for measuring MTF was thus developed, in which square wave chart image and Aluminium block images for obtaining characteristic curves are simultaneously exposed on the same film. MTF by the contrast method was found equivalent to that by the slit method. Differences between three phase and inverterunits at a tube voltage of 60kV aren't recognized.
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KAZUYA YAMASHITA, ATUSHI TAKIGAWA, TAKAYUKI ISHIDA, TOSHIHISA NAKANISH ...
Article type: Article
1992 Volume 48 Issue 4 Pages
616-624
Published: April 01, 1992
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The purpose of this work is to develop an integrated evaluation method by generalizing fuzziness in subjectively evaluating sharpness, radiographic graininess, and contrast, which are commonly used for characterizing image quality. For this purpose, a fuzzy measure which is one of fuzzy theory and a fuzzy integral using the fuzzy measure were applied. We selected 5 chest radiographs from each of the 4 facilities (university hospitals : 2, national hospital : 1, company clinic : 1), and carried out an examination using 6 observers. As primarily objective points for the observation, 5 places on a chest radiograph were chosen, and rated the image quality factors of the partial images by a method of score summation. Fuzzy integral was turned into the rating score using each factor, the fuzzy measure in each objective point which was fixed separately. As a result, an integrated evaluation of image quality factors became possible. Also, an integrated evaluation of chest radiographs was possible and the quality was rated by using fuzzy integral of each objective point. Furthermore, also evaluated the "impressive" image quality of radiographs at the time of rating each objective point. The results almost coincided. It was concluded that fuzzy measure and integrated evaluation of image quality according to the fuzzy integral could be newly developed.
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KOICHI CHIDA, HIDEHARU SAKAKIDA, MASAMI SATO, MASAHIRO SAI, RYOUJI ITA ...
Article type: Article
1992 Volume 48 Issue 4 Pages
625-632
Published: April 01, 1992
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A comparison was made of four X-ray analyzers including a new type and conventional direct measuring methods. Values for voltage by X-ray analyzers agreed with those by conventional direct measuring methods for the 2 peak, 12 peak, and constant potential generators. Exposure periods determined by X-ray analyzers also agreed with those by conventional direct measuring methods over 10 msec. The stability and reproducibility results by X-ray analyzers are excellent. They are thus applicable to the quality control of X-ray generators. There are two types of the X-ray analyzers; one is for the storage of data, and the other is not. They differ in size. A more appropriate type should be used according to certain purposes and conditions. In the case of inverter type X-ray generators with the same percent ripple and frequency as constant potential generators, the data for tube voltage by X-ray analyzers agreed with those by conventional direct measuring methods. In the case of generators with larger ripple and higher frequency, the data differed from those by conventional direct measuring methods. The error is attributed to the sampling time of X-ray analyzers.
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AKIO OGURA, YOSHIKI NAKAYAMA
Article type: Article
1992 Volume 48 Issue 4 Pages
633-639
Published: April 01, 1992
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Computed tomographic (CT) scanning has made significant contributions to the diagnosis and evaluation of temporal bone lesions by the thin-section, high-resolution techniques. However, these techniques involve greater radiation exposure to the lens of patients. A means was thus sought for reducing the radiation exposure at different scanning angles such as+15 degrees and -10 degrees to the Reid's base line. Purposes of this study were to measure radiation exposure to the lens using the two tomographic planes and comparison was made of the ability to visualize auditory ossicles and labyrinthine structures. Visual evaluation of tomographic images on auditory ossicles was made by blinded methods using four rankings by six radiologists. The statistical significance of the intergroup difference in the visualization of tomographic planes was assessed for a significance level of 0.01. Thermoluminescent dosimetor chips were placed on the cornea of tissue equivalent to the skull phantom to evaluate radiation exposure for two separate tomographic planes. As the results, tomographic plane at an angle of -10 degrees to Reid's base line allowed better visualization than the other plane for the malleus, incus, facial nerve canal, and tuba auditiva (P<0.01). Scannings at an angle of -10 degrees to Reid's base line reduced radiation exposure to approximately one-fiftieth (1/50) that with the scans at the other angle.
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HIROHARU OKADA, TAKASHI WAKAMATU
Article type: Article
1992 Volume 48 Issue 4 Pages
640-642
Published: April 01, 1992
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OSAMU YAMADA, HIROSHI KUMAGAI, OSAMU NAKAMURA
Article type: Article
1992 Volume 48 Issue 4 Pages
643-647
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[in Japanese]
Article type: Article
1992 Volume 48 Issue 4 Pages
648-658
Published: April 01, 1992
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[in Japanese]
Article type: Article
1992 Volume 48 Issue 4 Pages
659-670
Published: April 01, 1992
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[in Japanese], [in Japanese]
Article type: Article
1992 Volume 48 Issue 4 Pages
671-674
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[in Japanese]
Article type: Article
1992 Volume 48 Issue 4 Pages
675-686
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[in Japanese]
Article type: Article
1992 Volume 48 Issue 4 Pages
687-688
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[in Japanese]
Article type: Article
1992 Volume 48 Issue 4 Pages
689-690
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[in Japanese]
Article type: Article
1992 Volume 48 Issue 4 Pages
691-
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[in Japanese]
Article type: Article
1992 Volume 48 Issue 4 Pages
691-
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
692-695
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
696-697
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
698-703
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
704-
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
705-719
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
720-722
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
722-
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
App15-
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Article type: Appendix
1992 Volume 48 Issue 4 Pages
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Article type: Cover
1992 Volume 48 Issue 4 Pages
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Published: April 01, 1992
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