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1997 Volume 53 Issue 12 Pages
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Article type: Cover
1997 Volume 53 Issue 12 Pages
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Article type: Index
1997 Volume 53 Issue 12 Pages
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Article type: Index
1997 Volume 53 Issue 12 Pages
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[in Japanese]
Article type: Article
1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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Article type: Appendix
1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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EIJI MATSUDA, TAIZO SANADA, GO HITOMI, KOKI KAKUBA, YOSHIHARU KANGAI, ...
Article type: Article
1997 Volume 53 Issue 12 Pages
1779-1784
Published: December 20, 1997
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We developed a new method for bootstrap sensitometry that obtained the characteristic curve from a wide range, with a smaller number of aluminum steps than the conventional bootstrap method. In this method, the density-density curve was obtained from standard and multiplied exposures to the aluminum step wedge and used for bootstrap manipulation. The curve was acquired from two regions separated and added together, e.g., lower and higher photographic density regions. In this study, we evaluated the usefulness of a new cinefluorography method in comparison with N.D. filter sensitometry. The shape of the characteristic curve and the gradient curve obtained with the new method were highly similar to that obtained with N.D. filter sensitometry. Also, the average gradient obtained with the new bootstrap sensitometry method was not significantly different from that obtained by the N.D. filter method. The study revealed that the reliability of the characteristic curve was improved by increasing the measured value used to calculate the density-density curve. This new method was useful for obtaining a characteristic curve with a sufficient density range, and the results suggested that this new method could be applied to specific systems to which the conventional bootstrap method is not applicable.
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NOBUHIRO YOSHIDA, TOSHIAKI OKAMOTO, HIDEKADO TAKAHASHI, TERUO HATTORI
Article type: Article
1997 Volume 53 Issue 12 Pages
1785-1788
Published: December 20, 1997
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We investigated the possibility of using venous blood sampling instead of arterial blood sampling for the current method of ARG(autoradiography) used to determine regional cerebral blood flow(rCBF) on the basis of one session of arterial blood sampling and SPECT. For this purpose, the ratio of the arterial blood radioactivity count to the venous blood radioactivity count, the coefficient of variation, and the correlation and differences between arterial blood-based rCBF and venous blood-based rCBF were analyzed. The coefficient of variation was lowest(4.1%) 20 minutes after injection into the dorsum manus. When the relationship between venous and arterial blood counts was analyzed, arterial blood counts correlated well with venous blood counts collected at the dorsum manus 20 or 30 minutes after intravenous injection and with venous blood counts collected at the wrist 20 minutes after intravenous injection(r=0.97 or higher). The difference from rCBF determined on the basis of arterial blood was smallest(0.7) for rCBF determined on the basis of venous blood collected at the dorsum manus 20 minutes after intravenous injection.
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AKIO OGURA, HIROSHI INOUE, MITSUJI HIGASHIDA, MASARU YAMAZAKI, TOMOYUK ...
Article type: Article
1997 Volume 53 Issue 12 Pages
1789-1794
Published: December 20, 1997
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Image uniformity refers to the ability of the MR imaging system to produce a constant signal response throughout the scanned volume when the object being imaged has homogeneous MR characteristics. To facilitate the determination of image uniformity in diagnostic magnetic resonance images, reports such as the NEMA Standard and AAPM report have been issued. However, these methods of evaluation are impractical in cases such as the day-to-day quality control of the machine or comparisons between the different MR systems, because these methods affect the signa-to-noise ratio(SNR) and create problems by displaying nonuniformity locations. Therefore, we present a new method for evaluating uniformity, called the test segment method. The influence of SNR on the NEMA test and the segment method were examined. In addition, the results of the two methods were compared for certain nonuniformity conditions, Results showed that the segment method did not affect SNR and provided good display of nonuniformity.
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YASUHIRO NISHIMOTO, MASATO TANAKA, TETSUYA FUKUSHIMA, HIROYUKI SASHIE, ...
Article type: Article
1997 Volume 53 Issue 12 Pages
1795-1801
Published: December 20, 1997
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Misregistration artifact is the major cause of image degradation in digital subtraction angiography(DSA). As three-dimensional movement of the body causes uneven misregistration on two-dimensional images, conventional linear correction is not sufficient. We developed a nonlinear geometric warping technique. Using a local least-square matching method, we obtained the shift values sampled at 49 reference points in a 512×512 matrix. They were then fitted to the spline function to calculate pixel-by-pixel shift values. With these values, nonlinear geometric warping of the mask image followed. As a result, misregistration artifact was almost non-existent in the processed images, and vascular anatomy was clearly delineated even in the skull base region. This newly proposed method is a simple, practical way to reduce misregistration artifacts in DSA.
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TOSHIMINE YABUTANI, TAKESHI SAWADA
Article type: Article
1997 Volume 53 Issue 12 Pages
1802-1808
Published: December 20, 1997
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Fixation of the irradiated part at radiotherapy is an important problem. One solution is the use of a fixation device with a thermo-plastic shell. We studied various thermo-plastic shell materials in order to compare their kinking characteristics. The shell materials examined were Orfit(thickness:2mm), Posicast(thickness:2mm), Uni-frame(thickness:2.4mm), Radicast(thickness:2mm), Shellfitter(thickness:3mm), Thermoshell-S(thickness:3mm) and Thermoshell-P(thickness:3mm). We measured relative dose ratio at the surface and at the calibration point, and the shrinkage ratio of the shell materials after they had hardened. We compared the accuracy of fixation and impressions from test subjects when the various fixation devices were used. Results showed that the surface dose was increased about threefold, and the calibration point dose was decreased 0.6% when the fixation devices were used. The shell materials shrunk about 1% within a few hours after they had become hard. However, there was no difference between materials after that. The mesh-type shells were preferred by the test subjects. Set-up reproduction was dependent on technological precision in shaping and putting on the fixation device. In addition, shell materials should be chosen for the following factors:1) ease of use, 2) comfort for patients, 3) cost of preparation.
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JOJI KATO, YOSHIHIKO KAWAMURA, HARUYOSHI SAITO, KOUICHIROU ITO, SUSUMU ...
Article type: Article
1997 Volume 53 Issue 12 Pages
1809-1815
Published: December 20, 1997
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In order to obtain the optimal conditions for cranial MRA by a rapid imaging method(fast card STAR), to which the principle of signal targeting with alternating radiofrequency(STAR method) was applied, we carried out a basic study on normal volunteers. According to the results, the vascular signal was weaker with FA 10 degrees, and ghost artifact was observed above 60 degrees. The FA at which good imaging of even peripheral vessels could be obtained was about 30 degrees. The visibility of the peripheral part increased with increased in-flow inversion time(TI), but at TI 500ms, some weakening of the vascular signals was observed. Considering the imaging of peripheral vascularity and vascular contrast, TI 400ms seemed to be most suitable. Regarding VPS(views per segment:collecting number of k-space lines during one cardiac pulse), slight blurring was observed at VPS 16, and this blurring caused a marked decrease in visibility at VPS 32. Although the VPS setting depends on imaging time, the imaging time for VPS 8 was short(about 30-60 sec) and artifact noise was slight. Thus, it was considered to be useful. This method reduced artifact noise under the optimal conditions for FA, TI and VPS and provided good images of blood vessels, showing that this method is useful.
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YASUYUKI TAKAHASHI, HISASHI SHINOHARA, TAKAKI NARIMATSU, ISAO KAWAMATA ...
Article type: Article
1997 Volume 53 Issue 12 Pages
1816-1825
Published: December 20, 1997
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We considered it important to determine how each municipal government interprets and promulgates the Medical Service Law as it affects the field of radiology and procedures such as general X-ray diagnosis, CT, RI, radiation therapy and MR imaging. Only the government administrative segment referred to as the medical supervi-sory body can observe, control and generally administer front-line medical sites such as hospitals and clinics. This administrative body should have better public health care as its objective and should be able to adapt to changes in technology and the environment. We consider that, under the current climate of rapid technological change, medical supervision cannot be effective unless teams of specialists from each field are involved in administrative guidance. With the goal of achieving optimal and effective use of medical radiology, a question-naire survey was done to gather information. Two questions were raised:(1) Is there sufficient interaction between public medical supervisors and radiologists? and (2) bow well do people on the fornt lines at medical sites understand the current control structure?
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TAKAO ISE, [in Japanese], [in Japanese], [in Japanese], [in Japanese], ...
Article type: Article
1997 Volume 53 Issue 12 Pages
1826-1849
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KAZUO AWAI
Article type: Article
1997 Volume 53 Issue 12 Pages
1850-
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YOSHIMI FUKUMOTO
Article type: Article
1997 Volume 53 Issue 12 Pages
1851-1853
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KAZUYA YAMAGUCHI
Article type: Article
1997 Volume 53 Issue 12 Pages
1853-1855
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NOBORU SHIGETANI
Article type: Article
1997 Volume 53 Issue 12 Pages
1855-1859
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SHOICHI SUZUKI
Article type: Article
1997 Volume 53 Issue 12 Pages
1859-1861
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TSUNEO YAMADA
Article type: Article
1997 Volume 53 Issue 12 Pages
1862-1867
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1997 Volume 53 Issue 12 Pages
1868-1869
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[in Japanese]
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1997 Volume 53 Issue 12 Pages
1870-
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Article type: Appendix
1997 Volume 53 Issue 12 Pages
1871-1872
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1997 Volume 53 Issue 12 Pages
1873-1874
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1997 Volume 53 Issue 12 Pages
1875-1876
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[in Japanese]
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1997 Volume 53 Issue 12 Pages
1877-
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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Article type: Article
1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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1997 Volume 53 Issue 12 Pages
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