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Volume 46, Issue 1
Displaying 1-29 of 29 articles from this issue
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Article type: Cover
1990 Volume 46 Issue 1 Pages Cover1-
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
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Article type: Index
1990 Volume 46 Issue 1 Pages Toc1-
Published: January 01, 1990
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Article type: Index
1990 Volume 46 Issue 1 Pages Toc2-
Published: January 01, 1990
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Article type: Appendix
1990 Volume 46 Issue 1 Pages i-viii
Published: January 01, 1990
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Article type: Appendix
1990 Volume 46 Issue 1 Pages ix-xiii
Published: January 01, 1990
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MASAAKI OGAWA, TADASHI SUNAYASHIKI, YUMIKO YAMANE, YOSHIE KODERA, TAKU ...Article type: Article
1990 Volume 46 Issue 1 Pages 1-6
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
JOURNAL FREE ACCESSSome types of filters to eliminate the grid pattern from a radiograph which was taken with an antiscatter grid were proposed. By visual evaluation, the acceptability of processed images was estimated. It was concluded that these filtering methods were effective in eliminating the grid pattern without reduction in image quality.View full abstractDownload PDF (766K) -
KEIZOU MIYAGOSHI, KIMIO USAMI, TAKASHI SATOArticle type: Article
1990 Volume 46 Issue 1 Pages 7-13
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
JOURNAL FREE ACCESSIt is known that the image contrast of radiography has been changed due to intensify screen of medical radiography. In this study, X-ray absorption energy of some intensifying phosphors (CaWO_4, Y_2O_2S : Tb, BaSO_4 : Eu, Gd_2O_2S : Tb) which transfer to light energy was calculated using the Monte Calro simulation for transmitted X-ray through a water phantom on incident various X-ray energy. As a result, the relative absorption energy in phosphors was changed by the energy absorption coefficients (ie. atomic number) of phosphors. Also, the lineality for absorption energy and the water phantom thickness was affected by the change in shape of X-ray spectra when transmitted from the phantom.View full abstractDownload PDF (645K) -
MANABU NAKATA, TAKEHIRO NISHIDAI, HIROKI NOHARA, TAKASHI OKADA, SHINSU ...Article type: Article
1990 Volume 46 Issue 1 Pages 14-21
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
JOURNAL FREE ACCESSA new three-dimensional (3-D) computation algorithm, "Modified equivalent TMR method", for photon beam dose calculation considering the heterogeneous correction has been developed. This algorithm in based on the modified equivalent TAR method that was proposed by Inamura et al. The modified equivalent TMR method has two calculation modes; the scatter mode which takes account for the 3-D contribution of scattered radiation and the non-scatter mode which doesn't. The dose distributions on off-central axis can be obtained from a approximate expression using the penumbra factor suggested by Shribastava and Cunningham. The purpose of this study is to evaluate the accuracy of dose computations using of this new algorithm. The accuracy is compared with both calculations and measurements on off-central axis for Cobalt-60 gamma rays and 10MV photon beams for various geometries and field sizes. Using the modified equivalent TMR method, we could show that the accuracy of 3-D dose computation on off-central axis with the scatter mode in unit-density phantom agreed with measured the data within 6%. For rectangular and irregular fields, this algorithm based on the scatter mode is accurate to a satisfactory lenel, while calculations on the off-central axis within the low density medium used two algorithm are inadequate in situation of electron disequilibrium, in particular near the beam edge. To satisfy the routine clinical needs of radiation therapy, it is highly desirable to develop a satisfactory approximation to situation of electron disequilibrium. In particular with present-day computers, it may take days of computation to obtain an accurate dose distribution in a single inhomogeneous medium. For new calculating algorithm that we have been developed, it may be applied with a suitable accuracy and reasonable computation time except for the electron disequilibrium regions.View full abstractDownload PDF (710K) -
TAKAYUKI ISHIDA, KAZUYA YAMASHITA, ATSUSHI TAKIGAWAArticle type: Article
1990 Volume 46 Issue 1 Pages 22-28
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
JOURNAL FREE ACCESSThe image that has been scanned to produce an analog signal which is then converted into digital form and stored in the frame memory, by means of a small scale image processing system. This time, the physical charactristics in these digitized images were extracted from the image analysis. The image processing system is comparatively low in price and very avaliable, and is able to be applied image analysis, various processing of digitized images. Sensitometric strips and slit images were made in the same way as the conventional method. These samples were scanned using a CCD camera; not using a microdensitometer. The modulation transfer factors (MTF's) of screen/film system was calculated by the Fourier transform method, by means of the digitized image data. There were hardly any difference between MTF that had been measured for the conventional system by means of microdensitometer and that which had been measured for our digital image processing system. This measurement method have several merits when compaed with the conventional method; The measurement time required was greatly shorten, and various influences were excluded which are nopmoely caused by a microdensitometer.View full abstractDownload PDF (667K) -
JUNJI SHIRAISHI, KAZUYOSHI TSUDAArticle type: Article
1990 Volume 46 Issue 1 Pages 29-34
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
JOURNAL FREE ACCESSIn the measurement of the slice thickness of computed tomography, many investigatiens and reports have been made on the improvement of computed tomography. Among these reports, the most popular method uses a thin Al plate placed on a slant against a cross section of the scannimg area at a 30 or 45 degree angle and calculates slice thickness from these computed tomography images. However, these methods are easily influenced by the filtered function, and poor accuracy when thin slice measurements are carried out (5mm or less). We have improved the measurement of the slice thickness of computed tomography that uses the partial volume effect and tested the original phantom with our new measurement method. As a result, our method has proven to be less influenced by the corrected function less than the ordinary method. Moreover, our method was more accurate for thin slice thicknesses. Therefore, we feel that our method is the most suitable method for measurements of slice thickness of computed tomography.View full abstractDownload PDF (777K) -
NOBUHIRO ODA, YOSHITERU HIRAMATSU, HARUHISA OGAWA, TUTOMU NAKANO, HIDE ...Article type: Article
1990 Volume 46 Issue 1 Pages 35-39
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
JOURNAL FREE ACCESSImmobilizing pad suppressing motion artifact in abdominal intravenous digital subtraction angiography (IVDSA). A new device suppressing motion artifact in abdominal intravenous digital subtraction angiography (IVDSA) was made. It consists of a styrol foam pad and magic fastener bands. The styrol foam pad is fastened tightly to press the patient's upper abdominal portion by the bands. This device not only minimizes the motion artifact but improves image quality by decreasing the subject thickness.View full abstractDownload PDF (506K) -
HITOSHI GOSHIMAArticle type: Article
1990 Volume 46 Issue 1 Pages 40-44
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
JOURNAL FREE ACCESSAmong many different factors affecting MR image qualities, scanning parameters including spatial, density and temporal resolutions, in particular, should be controlled principally by the operator. This paper presents measures to improve the author's study focuses on the MRI phantom for which we examine the four physical parameters ρ, T_1, T_2, and Q. The author elucidates that the prerequisite imposed on the MRI-phantom is that every parameter cited should be, without exception. equivalent to that of the living tissue. The PVA gel is presented below as an elementary material that meets our requirement.View full abstractDownload PDF (455K) -
TAKESHI SAWADAArticle type: Article
1990 Volume 46 Issue 1 Pages 45-52
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
JOURNAL FREE ACCESSSome technical problems concerning the MRI were studied, on the basis of 20 months' experiences with 1, 500 patients, using the apparatus of Shimazu SMT-150 (1.5T). This report contained such problems as follows : 1. Space leakage of magnetic fields was surveyed, and the methods of maintenance of the apparatus was discussed. 2. Slice thickness of MRI was measured and compared with that of CT. 3. T_1 and T_2 relaxation time was measured using diluted Gd-DTPA solution. 4. In respect of susceptibility artifacts of MRI, an investigation was performed. 5. Some other technical trials and attempt were presented.View full abstractDownload PDF (993K) -
[in Japanese]Article type: Article
1990 Volume 46 Issue 1 Pages 53-56
Published: January 01, 1990
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OSAMU TAKIZAWAArticle type: Article
1990 Volume 46 Issue 1 Pages 57-62
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
JOURNAL FREE ACCESSThe MRI technique is now introduced in the clinical sites as a clinical diagnostic modality. As the NMR technique itself, it is still incomplete and is rapidly developping. In this paper, the problems of the presently existing MR technique are discussed especialy for the long examination time, moving artifact and the S/N ratio for the thin slice imaging. Based on these problems. the technique which is now going to be introduced in the clinical examination are explained. For the implimentation of these techniques and for the best use of them it is strongly required to accumulate the experiences and the deep technical considerations. These include fast scan imaging, the motion artefact suppression, 3D volume scan and MR angiography. In the lase part of the paper, we discuss the field where MR can take part in for the future clinical Medicine, which may include the fast imaging and the tissue characterization such like organ function analysis.View full abstractDownload PDF (597K) -
HIROMI KAWAGUCHIArticle type: Article
1990 Volume 46 Issue 1 Pages 63-67
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
JOURNAL FREE ACCESSRecently the tequnologies of MRI and MRS had been advanced so brilliantly. On the view point of the method of imaging reconstruction almost every systems use Fourier Zeugmatography method. But they still have independent characteristics. This thesis gives some interpretation to these characteristics.View full abstractDownload PDF (603K) -
[in Japanese]Article type: Article
1990 Volume 46 Issue 1 Pages 68-
Published: January 01, 1990
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...Article type: Article
1990 Volume 46 Issue 1 Pages 69-71
Published: January 01, 1990
Released on J-STAGE: June 29, 2017
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...Article type: Article
1990 Volume 46 Issue 1 Pages 72-73
Published: January 01, 1990
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Article type: Appendix
1990 Volume 46 Issue 1 Pages 74-78
Published: January 01, 1990
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Article type: Appendix
1990 Volume 46 Issue 1 Pages 80-81
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Article type: Appendix
1990 Volume 46 Issue 1 Pages 82-89
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Article type: Appendix
1990 Volume 46 Issue 1 Pages 90-95
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Article type: Appendix
1990 Volume 46 Issue 1 Pages 96-114
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Article type: Appendix
1990 Volume 46 Issue 1 Pages 114-
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Article type: Appendix
1990 Volume 46 Issue 1 Pages 114-
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Article type: Appendix
1990 Volume 46 Issue 1 Pages 115-
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Article type: Appendix
1990 Volume 46 Issue 1 Pages 116-
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Article type: Cover
1990 Volume 46 Issue 1 Pages Cover2-
Published: January 01, 1990
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