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Article type: Cover
1997 Volume 53 Issue 4 Pages
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Article type: Cover
1997 Volume 53 Issue 4 Pages
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Article type: Index
1997 Volume 53 Issue 4 Pages
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Article type: Index
1997 Volume 53 Issue 4 Pages
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
I-
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Article type: Appendix
1997 Volume 53 Issue 4 Pages
II-IV
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Article type: Appendix
1997 Volume 53 Issue 4 Pages
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Article type: Appendix
1997 Volume 53 Issue 4 Pages
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Article type: Appendix
1997 Volume 53 Issue 4 Pages
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Article type: Appendix
1997 Volume 53 Issue 4 Pages
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Article type: Appendix
1997 Volume 53 Issue 4 Pages
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JUNJI SHIRAISI, HIROKO UEDA, AKANE UTSUNOMIYA, NOBUKO HANAOKA, DAISAKU ...
Article type: Article
1997 Volume 53 Issue 4 Pages
431-436
Published: April 20, 1997
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We developed an approach to receiver operating characteristic(ROC)analysis that employs the mean and standard deviation of CT vaules for measuring density detection by CT scanner. A CT phantom(PPE resin)for evaluating low-contrast detectability was imaged for case samples. The mean and standard deviation of CT values within regions of interest(ROIs)that were set in a simulated nodule within the CT phantom were used as actually positive data. The values in ROIs of the same size in the same images that did not contain a nodule were used as actually negative data. Density detectability was summarized by the ROC area index Az. Detectabilities were measured with two types of CT scanners for varying absorbed doses. From the experimental results, there were statistically significant differences in density detectability between the several combinatons of exposed dose. We conclude that our new method is useful for measuring density detectability and is correlated with the results obtained from observer-performance study of low-contrast detectability. Furthermore, our method offered better performance in detecting statistically significant differences than the observer performance study.
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HITOSHI BABA, SATOSHI HIROWATARI, HIROYUKI NISHIMURA, KAZUHISA OGAWA, ...
Article type: Article
1997 Volume 53 Issue 4 Pages
437-442
Published: April 20, 1997
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Many studies have reported improvements in the measurement of section sensitivity profiles of X-ray computed tomography(CT). The method(partial volume method, PVM)to calculate section sensitivity profiles from mean computed tomography numbers of two materials in a section(and by varying the ratio of their volume) was reported by us and Shiraishi et al. However, the section sensitivity profiles of this method differed from the true section sensitivity profiles. Therefore, we developed a method using an air gap(air gap method, AGM). Measurement with this method was more accurate than that of PVM and was not affected by filter function. The air gap method is the most suitable method for the measurement of section sensitivity profiles of computed tomography.
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YOSHIO YOSHINO, AKIO HAYAMI, MASAO YANO, TSUYOSHI MATSUO, MASAO ARUGA, ...
Article type: Article
1997 Volume 53 Issue 4 Pages
443-447
Published: April 20, 1997
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We evaluated the diagnostic accuracy and image quality of the dry-processing laser imaging system Dry View using CR, DR, and CT images by comparing the results of ROC analysis, the Kyoto University method for chest images, and our original method using the WET system. There were no statistically significant differences in diagnostic accuracy between ROC analysis and the Kyoto University method, (Az value : DRY=0.851, WET=0.860, total points : DRY=56.3, WET=56.0). Image quality assessment(contrast, graininess, sharpness, and structure visibility)revealed no significant differences in structure visibility. The WET system was judged to have better graininess in CR and DR and better contrast in DR.DRY was judged to have better sharpness in CT images. The diagnostic accuracy and image quality of the Dry View system were equal to those of WET system.
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YOICHI EGUCHI, TOSHIMITSU SATOU, KOUJI SUZUKI, YUJI KAGA, AKIHITO TAKA ...
Article type: Article
1997 Volume 53 Issue 4 Pages
448-453
Published: April 20, 1997
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A new X-ray image intensifier(Toshiba J-type I.I.)has been developed in response to the digital X-ray image requirements of recent diagnostic systems. In the J-type I.I., the input phosphor screen(450-μm thick, CsI)has been deposited directly on the input window. Since there is no space between the input window and phosphor screen, the scattering of X-rays at the input window is reduced. Consequently, the X-ray detection efficiency over a wide range of X-ray tube operating voltages is also improved. Our studies have shown that the 10-mm contrast ratio is 24(for a 9 inch I.I.). Using International Electrotechnical Commission(IEC)Standard methods, we have concluded that the detective quantum efficiency(DQE)is 70%. We have also compared the characteristics of the J-type I.I.with those of the conventional G-type I.I. using the DFP-2000A DF system(TOSHIBA). The main results are enumerated below. (1)The veiling-glare fraction(VGF)was about 5% less for the J-type I.I. (2)The resolution quality was the same for both types of I.I. (3)Noise was less for the J-type I.I.because of the improvement in DQE. (4)The signal to noise ratio was higher for the J-type I.I.because of the reduction of noise. (5)Receiver operating characteristic(ROS)analysis showed that signal detectability was better for the J-type I.I.
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HIRONOBU ARAKI, MICHIAKI KAI, TOMOKO KUSAMA
Article type: Article
1997 Volume 53 Issue 4 Pages
454-459
Published: April 20, 1997
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In Japan, upper GI-tract X-ray examinations are widely conducted as mass screenings. From the view-point of radiation protection, justification for the examination and optimization of radiation protection have been performed but not adequately, because various factors are related with the dose estimates. In previous studies, it was reported that the time of fluoroscopy varied greatly with medical facilities and radiation technicians. In order to obtain a basic information on the dose distribution, we investigated the time of fluoros-copy, the number of exposures and other data on the upper GI-tract X-ray examination. The number of subjects was 397, aged from 19 to 80. The average time of fluoroscopy for each radiological technician was 32 to 319 seconds. The average time of fluoroscopy per exposure was 4.6 to 19 secons, and mainly depended both on the facility and on the type, fluorography or radiography. The number of exposures varied between 7 and 24, not only according to the facility but also with the radiological technician. From these results, it was evident that optimization in upper GI-tract examination depended on the technical control of a radiological technician. This study suggested that it is necessary to take the dose distribution into account for the purpose of doing risk-benefit analysis of the upper GI-tract X-ray examination conducted as a mass screening.
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SATORU MATSUO, HIDEO ONISHI, KAZUO NOMA, TETSUO KIDA, MITSURU KOMIZU, ...
Article type: Article
1997 Volume 53 Issue 4 Pages
460-466
Published: April 20, 1997
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Resolution with the modulation transfer function(MTF)of planar images in nuclear medicine has been used to evaluate the function of the pre-reconstruction filter used in single photon emission computed tomography(SPECT), in order to obtain high quality of SPECT images. In this study we compared presampling MTF used for evaluation of medical image resolution in digital subtraction angiography(DSA)and computed radiography(CR), with MTF which was approximated to the Gauss function from the full width at half maximum(FWHM), which is normalized by the National Electrical Manufacturers Association(NEMA). As a result, relative error of MTF between the two methods was approximately 10%. The effect of distortion in LSF caused by the addition of scattering appeared to be greater at full width at tenth maximum(FWTM)than at FWHM. Therefore, evaluation of a scintillation camera with only FWHM is limited when the system includes scattering. Evaluation of resolution by the presampling MTF method is useful for radionuclide images.
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SHIGERU SANADA
Article type: Article
1997 Volume 53 Issue 4 Pages
467-468
Published: April 20, 1997
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SHINICHIRO ISHIDA, [in Japanese], [in Japanese], [in Japanese], [in Ja ...
Article type: Article
1997 Volume 53 Issue 4 Pages
469-471
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SHOJI KIDO
Article type: Article
1997 Volume 53 Issue 4 Pages
471-474
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SHIGEHIKO KATSURAGAWA
Article type: Article
1997 Volume 53 Issue 4 Pages
474-477
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HISASHI YOSHITA
Article type: Article
1997 Volume 53 Issue 4 Pages
478-483
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TATSUSHI TOMOMITSU
Article type: Article
1997 Volume 53 Issue 4 Pages
484-485
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MASAKO ITO
Article type: Article
1997 Volume 53 Issue 4 Pages
485-489
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MITSURU KAWAKATSU
Article type: Article
1997 Volume 53 Issue 4 Pages
489-493
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TAIZO SANADA
Article type: Article
1997 Volume 53 Issue 4 Pages
493-497
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MASAO FUKUNAGA
Article type: Article
1997 Volume 53 Issue 4 Pages
498-501
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KAZUTAKA MASUDA, [in Japanese], [in Japanese], [in Japanese], [in Japa ...
Article type: Article
1997 Volume 53 Issue 4 Pages
501-504
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YOSHIO YANAGIHARA
Article type: Article
1997 Volume 53 Issue 4 Pages
505-
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MASAYUKI KUMASIRO
Article type: Article
1997 Volume 53 Issue 4 Pages
505-510
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TSUTOMU IGARASHI
Article type: Article
1997 Volume 53 Issue 4 Pages
511-513
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MASAAKI KAGAWA, [in Japanese], [in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
514-518
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TOSHIHARU SAKUMA
Article type: Article
1997 Volume 53 Issue 4 Pages
519-522
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YASUAKI SHOJI
Article type: Article
1997 Volume 53 Issue 4 Pages
522-526
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
527-528
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
528-
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
528-
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
528-
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
528-529
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
529-
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
529-
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
529-530
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[in Japanese]
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1997 Volume 53 Issue 4 Pages
530-
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
530-531
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[in Japanese]
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1997 Volume 53 Issue 4 Pages
531-
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
531-
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
531-533
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
533-
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
533-534
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 4 Pages
534-
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