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Volume 18 (2001)
- Issue 3 Pages 114-
- Issue 2 Pages 66-
- Issue 1 Pages 2-
Volume 18, Issue 2
Displaying 1-5 of 5 articles from this issue
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Kunio DOI2001 Volume 18 Issue 2 Pages 66-69
Published: May 05, 2001
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSDownload PDF (901K) -
Masao INUI2001 Volume 18 Issue 2 Pages 70-74
Published: May 05, 2001
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSSensitometry methods needed plural times of X-ray exposure, and it was necessary to monitoring X-ray intensity between exposures. Single exposure was desired to sensitometry for the radiographic screen-film systems. We developed a sensitometry method for the radiographic screen-film systems with single exposure in which two stacked screen-film systems, ingenious use of K absorption edge and the integral method for sensitometry were used. Then a characteristic curve obtained by the new sensitometry method was compared with these obtained by other methods, validity of the new method were confirmed.View full abstractDownload PDF (939K) -
Dang Thanh TIN, Seihaku HIGUCHI2001 Volume 18 Issue 2 Pages 75-82
Published: May 05, 2001
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSThe main idea used in the scheme is the modification of conditional probabilities at cross points which are neighbor points around points of gray levels 2'. Moreover, the compression ratio is also improved by gray code transform and by the gray transformation. Gray code transform is useful for coarsely encoding bit-planes from image decomposition, and the gray transformation decreases the gray levels used in histogram. In order to adapt the conditional probability to the variation of gray level, we have to use an algorithm which is with the processing form of “First In First Out”, that is Jones' method. This algorithm and the ideas above applied to lossless compression, especially to coding medical images which are available to the diagnosis. Applications to lossless medical image compression and cryptography are suggested.View full abstractDownload PDF (2213K) -
Isao YAMADA, Kazuo TANAKA, Du-Yin TSAI, Maroki SHIBAYAMA, Yasunobu KAM ...2001 Volume 18 Issue 2 Pages 83-86
Published: May 05, 2001
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSRecently, digital image apparatus such as CT, MRI, US are used in medical diagnosis. Cathode Ray Tube (CRT) diagnosis is now accepted in some clinical situations because of improvements of display technology. A generalization of the two-dimensional random checkerboard process is described and we developed a new calculation method for correlation in any directions around contiguous square regions permitting a continuous gray levels. Autocorrelation function of this model is obtained. Theoretical autocorrelation function and Wiener spectrum are calculated using this model.View full abstractDownload PDF (515K) -
Tosiaki MIYATI, Hiroshi FUJITA, Shigeru SANADA, Kichiro KOSHIDA, Toshi ...2001 Volume 18 Issue 2 Pages 87-92
Published: May 05, 2001
Released on J-STAGE: August 27, 2012
JOURNAL FREE ACCESSA method was developed to accurately measure signal-to-noise ratios (SNRs) in positive and negative frequencies of magnetic resonance images (MRIs). SNR2(f) was calculated from the modulation transfer function (MTF) and the Wiener spectrum, both of which were determined with subtracted complex images at the same phantom setting. The SNR2(f)s in the conventional spin echo (SE) and Turbo SE which set effective echo time at the first echo were evaluated by changing the T2 of the phantom in the frequency and phase encode directions. SNR2s gave positive and negative spatial frequency information that was not obtained with conventional methods. In this method, the influences of image nonuniformity and unnecessary artifacts could be eliminated. Analysis of the SNR in the spatial frequency domain made it possible to obtain more detail on the image quality of MRI.View full abstractDownload PDF (1168K)
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