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Article type: Cover
1993 Volume 49 Issue 11 Pages
Cover5-
Published: November 01, 1993
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Article type: Index
1993 Volume 49 Issue 11 Pages
Toc5-
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Article type: Index
1993 Volume 49 Issue 11 Pages
Toc6-
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Article type: Appendix
1993 Volume 49 Issue 11 Pages
i-viii
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Article type: Appendix
1993 Volume 49 Issue 11 Pages
ix-xiii
Published: November 01, 1993
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JUNICHI SASAKI, KIYOSHI HATA, KAZUO IZAWA, KIYOTO KAWANABE
Article type: Article
1993 Volume 49 Issue 11 Pages
1858-1864
Published: November 01, 1993
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We have developed a new measuring device for accurate and easy setup of tangential field beam irradiation treatment planning for early breast cancer. The new measuring device consists of five parts : (1) bridge and two pointers ; (2) angle gauge ; (3) two scales for width of field ; (4) angle scale with a pair of calipers indicated by the setup point ; and (5) thumb for the target depth. Using the new measuring device, we can easily and quickly determine separation, gantry angle, width of field, setup point and target depth (calculation depth) without calculations and directly obtain the setup point on skin (breast) surface. The new measuring device is an useful device for the setup of tangential field beam irradiation treatment planning of early breast cancer.
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KIYOSHI SAKAMOTO, MITSURU NAKAMURA, MASAHIKO ODA, NOBUKAZU AOYAMA, TAK ...
Article type: Article
1993 Volume 49 Issue 11 Pages
1865-1871
Published: November 01, 1993
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A new compensating filter method for digital subtraction angiography (DSA) employing the epoxy hardening system and geometric unsharpness has been developed. It is possible to use various powders as filter material, to modify the X-ray attenuation effect by changing the mixed ratio of epoxy resin to powder and to reduce the artifacts by post-processing (pixel-shift) in DSA image. The materials of the filter are made of 0.96g/(cm)^2 copper powder or 0.34g/(cm)^2 barium sulfate which is hardened with epoxy resin. The filter is of a block shape and is 26×26×8(mm)^3, in size about 1/15 of each object. Then, it was placed in front of X-ray focus at a distance of 65mm to increase geometric unsharpness. When the object is positioned, the object has to be set at a suitable position because the conpensating filter is fixed. As a result of this method, the artifacts caused by post-processing could be reduced and it was possible to shorten the fluoroscopic time by filter handling and reduce the radiation dosage the patients and operators are exposed to.
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SHIGERU SANADA, TAKASHI MIZUSHIMA, TOMOYUKI YAMAMOTO, HIDEO TUJII, SUS ...
Article type: Article
1993 Volume 49 Issue 11 Pages
1872-1878
Published: November 01, 1993
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To compare the diagnostic quality of mammographs obtained with a computed radiographic (CR) system with that obtained with screen-film systems, an observer performance test, using phantom images, was carried out. The CR system tends to be superior in detectability of microcalcifications, masses and spicules to the screen-film systems used. This is probably due to lower noise characteristics of the CR system at high spacial frequencies, although the resolution of the CR system is worse than the screen-film systems. The results and general properties of CR system, which is the ability of printing appropriate film image by postprocessing, suggest that the CR mammography may be useful for mass screening of breast cancer.
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YOSHIHARU HIGASHIDA, YASUHIRO HIAI, TAKAO TAKADA, MUTSUMASA TAKAHASHI, ...
Article type: Article
1993 Volume 49 Issue 11 Pages
1879-1887
Published: November 01, 1993
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HIDEHO TABUCHI
Article type: Article
1993 Volume 49 Issue 11 Pages
1888-1897
Published: November 01, 1993
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KAZUHIKO SAITO
Article type: Article
1993 Volume 49 Issue 11 Pages
1898-1899
Published: November 01, 1993
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MASAHIRO HANMURA
Article type: Article
1993 Volume 49 Issue 11 Pages
1900-1908
Published: November 01, 1993
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In clinical MRI, the motion artifact is a serious problem for the quality of image. Especially, the ghost image produced by the oscillation of abdominal fat tissue is one of the most significant technical problems for abdominal MRI. The ghost image is closely related to the respiratory pattern of the patient, but this correlation has not been reported clinically. Therefore, we analyzed the ghost image using a moving-phantom that can imitate the respiratory movement, after that, we clinically investigated and reconsidered the scan parameters to eliminate the ghost. The moving-phantom can produce various respiratory patterns. For example, the frequency, amplitude, and the rest time can be changed freely. Diluted Gd-DTPA solution was used as a sample. The standard scan condition was fixed as table 1. We changed each parameter individually, and took the MR image by the spin-echo sequence. Next, we measured the length of the ghost image (=the length between the ghost image and its actual source), and evaluated the correlation of the ghost image and each the variable parameters that were changed. The length of the ghost image was directry proportional to TR, NAV (number of avaraging), FOV, and was inversely proportional to cycle to oscillation. On other hand, the amplitude of oscillation was related to the reduction of signal intensity of the ghost. These ghost factors were specified by this experience, and as a result, we can estimate the location and intensity of the ghost image before the MR study by knowing the patient's respiratory pattern.
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ISAO MURO, DAISAKU SUGA, KENJI MIYAGI
Article type: Article
1993 Volume 49 Issue 11 Pages
1909-1916
Published: November 01, 1993
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The cause of flow artifacts has been well known from the very early days of MRI development. The many methods for the reduction of these has been reported in the past. ECG gating, presaturation, rephasing and dephasing using a bipolar gradient are the representatives of them. The flow artifact may create by the unexpectedly changes of signal intensity, such as flow related enhancement, high velocity signal loss and phase shift due to using of the gradient. The purpose of this paper is to explain the phenomenon of these. We hope that the readers will understand the concept of this artifact and knowledge of the solution for these problems will be applied to each work.
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TSUKASA DOI, FUMIO UENOYAMA, YOSHIMASA MIZUNO, SEIICHI MASUDA, MITSUHI ...
Article type: Article
1993 Volume 49 Issue 11 Pages
1917-1923
Published: November 01, 1993
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Among several originated artifact of magnetic resonance imaging (MRI), the cause of (1) aliasing artifact, (2) truncation artifact, (3) crosstalk, (4) bounce point, (5) chemical shift and (6) susceptibility artifact were investigated based on the basic concept of voxel. In addition, we experimentally examined the patterns of appearance of artifact in MR images taken with different imaging parameters, in order to clearity the effects of artifacts on clinical images and to suggest possible response strategies. Clinicians consider the appearance of artifacts to be unavoidable and try to differentiate between real and false images in order to produce a correct diagnosis. By understanding the causes of artifacts, parameters can be selected to minimize adverse effects. Therefore, MRI should be configured to maximize efficiency in order to provide an image of a more diagnostic value.
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HIROSHI SUGIMOTO
Article type: Article
1993 Volume 49 Issue 11 Pages
1924-1928
Published: November 01, 1993
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MR artifacts are caused by not only movements of patient but also hardware malfunctions. In this article, some examples of artifacts caused by power circuit, RF circuit, main magnet and gradient system are shown. And daily maintenance method to check image quality is described.
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YOSHIHARU DANTOKO
Article type: Article
1993 Volume 49 Issue 11 Pages
1928-1930
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ISAMU MANO
Article type: Article
1993 Volume 49 Issue 11 Pages
1931-1933
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KIYOSHI HATA
Article type: Article
1993 Volume 49 Issue 11 Pages
1934-1937
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KAZUHIRO HATTORI
Article type: Article
1993 Volume 49 Issue 11 Pages
1937-1940
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KAZUTOSHI YABUTA
Article type: Article
1993 Volume 49 Issue 11 Pages
1940-1943
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MASAHIKO OKUMURA
Article type: Article
1993 Volume 49 Issue 11 Pages
1943-1945
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YASUSHI OSANAI
Article type: Article
1993 Volume 49 Issue 11 Pages
1946-1949
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TAKASHI ASAKURA
Article type: Article
1993 Volume 49 Issue 11 Pages
1950-1955
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NOBUHIRO KAKOI
Article type: Article
1993 Volume 49 Issue 11 Pages
1956-1960
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TOSHIHARU SAKUMA
Article type: Article
1993 Volume 49 Issue 11 Pages
1961-1967
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ATSUYUKI USUI
Article type: Article
1993 Volume 49 Issue 11 Pages
1968-1970
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ATSUSHI ONO
Article type: Article
1993 Volume 49 Issue 11 Pages
1971-1975
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TSUKASA DOI, KENSAKU KAWASUE
Article type: Article
1993 Volume 49 Issue 11 Pages
1976-1978
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Article type: Appendix
1993 Volume 49 Issue 11 Pages
1979-
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Article type: Appendix
1993 Volume 49 Issue 11 Pages
1980-1982
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Article type: Appendix
1993 Volume 49 Issue 11 Pages
1983-
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Article type: Appendix
1993 Volume 49 Issue 11 Pages
1983-
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Article type: Appendix
1993 Volume 49 Issue 11 Pages
1983-
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Article type: Appendix
1993 Volume 49 Issue 11 Pages
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Article type: Cover
1993 Volume 49 Issue 11 Pages
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