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Article type: Cover
1994 Volume 50 Issue 4 Pages
Cover13-
Published: April 01, 1994
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Article type: Index
1994 Volume 50 Issue 4 Pages
Toc13-
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Article type: Index
1994 Volume 50 Issue 4 Pages
Toc14-
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Article type: Appendix
1994 Volume 50 Issue 4 Pages
i-
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Article type: Appendix
1994 Volume 50 Issue 4 Pages
ii-vi
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YASUHIRO KAWAHARADA, ICHIROU KOYAMA, MASAMI YAMADA
Article type: Article
1994 Volume 50 Issue 4 Pages
489-496
Published: April 01, 1994
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We evaluated and reported the characteristics of flatness, dose distribution, and dose measurements in small radiation fields. The diameter of the small radiation fields were from 0.7cm to 2.9cm at the isocenter and the collimator built in the accelerator head was set for 4×4cm^2 with supplemental collimator placed 56cm from the target. The flatness and the characteristics of dose distribution were measured in these small radiation fields in the narrow beam methods with 6MV and 10MV X-ray beams from the linear accelerator, applying a three dimensional fixed multi-irradiation technique. The sensitive volume effects upon the measurements of field factor and tissue peak dose ratio (TPR) in the small radiation fields were measured by JARP ionization chamber, shallow ionization chamber, and Si-semiconductor detector, because of each own sensitive volume. We concluded that the Si-semiconductor detector with the smallest sesitive volume was the most suitable for the small field dosimeter.
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SHIGERU MIYAZAKI, TAKAMITU HARA, KAZUO MATUTANI, KAZUHIKO SAITO
Article type: Article
1994 Volume 50 Issue 4 Pages
497-504
Published: April 01, 1994
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The linearity of the X-ray output is an important factor in radiography. It is a composite of the linearities of the X-ray tube voltage, the X-ray tube current, and the exposure time. This paper focuses on the linearity of exposure time. Non-linearity of the X-ray output for short-time exposure became a problem when the three-phase X-ray generator was introduced. This paper describes the inverter-type X-ray generator, which is expected to become predominant in the future. previously, we investigated X-ray output linearity during short-time exposure using the technique of dynamic study. In this paper, we describe the application of a digital memory and a personal computer to further investigation. The non-linearity of the X-ray output was caused by irregular waveforms of the X-ray tube voltage found at the rise time and the fall time. When the rise time was about 0.6ms, the non-linearity was about 2%, which is negligibly small. The non-linearity due to the fall time of the X-ray tube varied greatly according to the X-ray tube current. For the minimum irradiation time of 1ms, 4% to 27% of the non-linearity was attributable to the fall time. The main cause was the stray capacitance of the X-ray high-voltage cables. When the X-ray tube current exceeded 400mA, the rise time was almost equal to the fall time, and the problem did not occur. Consequently, the ideal generator should have a fall time which is equal to the rise time of the X-ray tube voltage. Strictly speaking, such a generator should have rectangular waveforms.
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TATSUSHI TOMOMITSU, SHINICHI YANAGIMOTO, HIROAKI MIMURA, YUJI AKAZAWA, ...
Article type: Article
1994 Volume 50 Issue 4 Pages
505-510
Published: April 01, 1994
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The values of bone mineral density (BMD) obtained by different dual-energy X-ray absorptiometry systems are known to be not identical. In this study, the BMD values in the distal radius measured by various DXA instruments were cross-calibrated by in vivo study. The instruments studied were the QDR-1000 (Hologic), DPX-L (Lunar), and DCS-600 (Aloka). Cross calibration was performed by calculating the linear regression formulae of BMD values between different systems. The correlation coefficients (r) were 0.987-0.992. Therefore, highly reliable conversions of BMD values between different systems could be obtained in the distal radius. However, it was shown that the conversion formulae of BMD values in the distal radius were essentially different to those in the lumbar vertebrae or proximal femur.
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YOSHIYUKI ASAI, TOSHIYUKI AOI, MICHIHIRO YAMAGUCHI, TAROU SAKASHITA, Y ...
Article type: Article
1994 Volume 50 Issue 4 Pages
511-517
Published: April 01, 1994
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During radiographic imaging, it is very important that the results of physical evaluation correspond with that of the subjective evaluation. However the gradient curve, MTF and Wiener spectrum as physical indices do not correspondence to results of subjective evaluation. Utlizing the minimum perceptble density difference (ΔDmin), the human psychological effect is introduced into conventional psysical data. Our psychophysical data, by using ΔDmin, represent human eyes response to brightness, color tones and physical information quantity of screen/film systems. So the values of psychophysical data are in good agreement with the human vision sense when we observe X-ray films illuminated by viewing box. Therefore, it is very important when observing, we should include characteristics of human vision and the viewing box into its physical quantity.
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[in Japanese], [in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
518-527
Published: April 01, 1994
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[in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
528-534
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[in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
535-537
Published: April 01, 1994
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
1994 Volume 50 Issue 4 Pages
538-541
Published: April 01, 1994
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[in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
542-546
Published: April 01, 1994
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[in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
547-549
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
1994 Volume 50 Issue 4 Pages
550-551
Published: April 01, 1994
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[in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
552-556
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[in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
557-558
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
1994 Volume 50 Issue 4 Pages
559-562
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[in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
563-565
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[in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
566-569
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[in Japanese], [in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
570-573
Published: April 01, 1994
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[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
1994 Volume 50 Issue 4 Pages
574-575
Published: April 01, 1994
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Article type: Appendix
1994 Volume 50 Issue 4 Pages
576-588
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Article type: Appendix
1994 Volume 50 Issue 4 Pages
589-612
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Article type: Bibliography
1994 Volume 50 Issue 4 Pages
613-
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Article type: Bibliography
1994 Volume 50 Issue 4 Pages
613-
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Article type: Bibliography
1994 Volume 50 Issue 4 Pages
613-
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Article type: Appendix
1994 Volume 50 Issue 4 Pages
App7-
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Article type: Appendix
1994 Volume 50 Issue 4 Pages
App8-
Published: April 01, 1994
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Article type: Cover
1994 Volume 50 Issue 4 Pages
Cover14-
Published: April 01, 1994
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