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Article type: Cover
2005 Volume 61 Issue 7 Pages
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Article type: Index
2005 Volume 61 Issue 7 Pages
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Article type: Index
2005 Volume 61 Issue 7 Pages
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[in Japanese]
Article type: Article
2005 Volume 61 Issue 7 Pages
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
2-6
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2005 Volume 61 Issue 7 Pages
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2005 Volume 61 Issue 7 Pages
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
8-10
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
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2005 Volume 61 Issue 7 Pages
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
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2005 Volume 61 Issue 7 Pages
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2005 Volume 61 Issue 7 Pages
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2005 Volume 61 Issue 7 Pages
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
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MASATOSHI MITSUYA
Article type: Article
2005 Volume 61 Issue 7 Pages
917-
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SHINSUKE YANO
Article type: Article
2005 Volume 61 Issue 7 Pages
918-920
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MASATOSHI MITSUYA
Article type: Article
2005 Volume 61 Issue 7 Pages
921-925
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MASAYOSHI SUNAOKA
Article type: Article
2005 Volume 61 Issue 7 Pages
926-928
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KATSUHISA FUJITA
Article type: Article
2005 Volume 61 Issue 7 Pages
929-932
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Tomoyuki Maruyama
Article type: Article
2005 Volume 61 Issue 7 Pages
933-941
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ISAO FUJITA, [in Japanese]
Article type: Article
2005 Volume 61 Issue 7 Pages
942-950
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KYOJI HIGASHIMURA
Article type: Article
2005 Volume 61 Issue 7 Pages
951-958
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MINORU HOSOBA
Article type: Article
2005 Volume 61 Issue 7 Pages
959-964
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SATORU ISHII
Article type: Article
2005 Volume 61 Issue 7 Pages
965-971
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HIROSHI SUGIMOTO
Article type: Article
2005 Volume 61 Issue 7 Pages
972-973
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RYUJI IKEDA
Article type: Article
2005 Volume 61 Issue 7 Pages
974-975
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YUICHIRO TSUCHIYA
Article type: Article
2005 Volume 61 Issue 7 Pages
976-977
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We obtained dynamic chest radiographs (512×512, 8bit, 15fps) of four healthy volunteers during respiration using an I.I.system, and two imitation dynamic radiographs with a false digital mass was created. We performed customized block matching technique to obtain vector values of image from inspiratory to expiratory phase. The vector values was divided into a direction and transformed into the RGB color. Density was determined by the sum pixel length of movement in a local area during respiration phase. The created new static image was defined as the "kinetic color map". The mass was detected by temporal subtraction of kinetic color map. The evaluation of patient's collation and similar radiography searching was performed with the template matching method. The same person's similar coefficient was statistically high (P<0.01), and the superior search rate was obtained (100%). Our analysis technique was effective in diagnosis and risk management.
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HIDEKAZU NAMBU
Article type: Article
2005 Volume 61 Issue 7 Pages
978-979
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YOSHINORI FUNAMA
Article type: Article
2005 Volume 61 Issue 7 Pages
980-981
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HIROYUKI WATANABE
Article type: Article
2005 Volume 61 Issue 7 Pages
982-983
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We studied differences between VW and Physical Wedge. And We confirm if the film method effect for Dynamic Field like VW of dose profile and dose distribution and we estimate VW and PW each Wedge Angle and dose profiles and dose distribution using film method. Wedge Angle, dose profile and dose distribution calculated by the film analysis system through geometory based on ICRU24, and we made out VW and PW each dose profile and dose distribution from film measurement data using film analysis system, and we subtracted VW from PW. We found relation error of VW and PW from Wedge Angle measurement based on ICRU24. We found 20% relation error between VW and PW in edge of field according to comparison of Wedge dose profile and distribution using subtraction. Film method was effective measured for dose profile and distribution of Dynamic Field with fine position resolution.
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KIYOSHI INOUE
Article type: Article
2005 Volume 61 Issue 7 Pages
984-987
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Article type: Bibliography
2005 Volume 61 Issue 7 Pages
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Article type: Bibliography
2005 Volume 61 Issue 7 Pages
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KICHIRO KOSHIDA, TAKUMI SOTA, KIMIYA NOTO, ATSUSHI FUKUDA, KOSUKE MATS ...
Article type: Article
2005 Volume 61 Issue 7 Pages
989-996
Published: July 20, 2005
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Medical personnel involved in abdominal angiography are exposed not only to direct radiation but also scattered radiation from inspection tables, patients, image intensifiers, and the beam-limiting system (collimator), among others. Japanese standard JISZ4831 prescribes protective coats of at least 0.25mm lead equivalent, which is the uniform thickness of lead equivalent. The most commonly used protective coats are 0.25mm Pb, 0.35mm Pb, or 0.5mm Pb in thickness. The weight of a typical protective coat is about 3kg. While some coats weigh up to 6kg, wearing such heavy coats becomes physically burdensome as inspection time increases. The trade-off between physical burden and protection was considered by analyzing the X-ray intensity distribution and attenuation rate of scattered radiation in each position assumed by the medical staff. In the case of inspections performed at an x-ray tube voltage of 80kV, it may be possible to reduce the weight of the lead rubber apron by about 33%. Namely, the lead thickness can be reduced uniformly by 0.20mm Pb at 70cm and 0.05mm Pb at 100cm, when the shielding capability of a 0.25mm thick Pb layer is accepted as the standard at 40cm above the gonad position. The same range of permeated X-ray dose for the gonad position may be reduced as well. In the case of 110kV, when the lead thicknesses are 0.30mm Pb at 40cm and 70cm, and 0.10mm Pb at 100cm, it is possible to reduce the weight of the lead rubber apron by about 28%.
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SEIJI KAWAMURA, SHIGEHIRO FUKUSHIMA, YUKIYASU YOSHINAGA, HIDEMICHI KAW ...
Article type: Article
2005 Volume 61 Issue 7 Pages
997-1005
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The temporal image subtraction technique was applied to bone scintigraphy, using Photoshop(commercially available image processing software) and Morpher (public domain warping software). For the temporal subtraction images, 81 subtraction images (19 cases) were prepared by a method used to subtract the previous images from the current ones. Registration of the current and previous images was performed by manual operation using Photoshop, and warping was done using the warping function of Morpher. In addition, difference images prepared after correcting the distributions of radioactive isotopes of the current and previous images using the count of the pelvic region were also examined. Compared with manual operation, alignment of images by warping improved registration and reduced the generation of pseudo-images of subtraction images. The rate of identification of abnormal accumulation-enhanced regions and subjective evaluation by doctors was improved for warping more than for manual operation. Furthermore, abnormal hot regions, which are difficult to find in film images, could be found in three subtraction images. In addition, it was confirmed that abnormal hot regions become more visible in many cases by preparing subtraction images after correcting the count between images using the count of the pelvic region. Thus, it is suggested that the temporal image subtraction technique in bone scintigraphy enables more accurate observation of enhancement of or changes in abnormal hot regions, which will support diagnostic reading. It is considered that enhancement of or changes in abnormal hot regions will be more accurately understood through further detailed discussion in the future.
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HIROFUMI YAGI, HITOSHI KUBO, MASATAKA OITA, TOKUE KURODA
Article type: Article
2005 Volume 61 Issue 7 Pages
1006-1013
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Although patient exposure has been increasing in recent years, few institutions have dosimeters and are able to ascertain patients' exposure dose. Internationally, however, it is necessary to adopt safety levels for patient exposure doses, and guidance levels have been introduced. Therefore, the need for measurement in areas of x-ray diagnosis has been increasing. As a result, several societies concerned with radiation dose have been endeavoring to establish a calibration system of radiation measurement and a dosimeter calibration system, which are the basics of radiation protection. Ten regional centers for standardization of doses in x-ray diagnosis were established and have begun trials relating to dosimeter cross calibration. Our institution, as one of these centers, has instituted a trial. In this study, the cross-calibration field, the reliability of the cross-calibration skill of our regional center, and the standard uncertainty of cross calibration were investigated. As a consequence of the investigation, it was determined that our cross-calibration field follows the protocol of the Japanese Society of Radiological Technology, the difference between calibration factor/cross calibration factor obtained by JQA and our regional center is within 2.5%, and the expanded uncertainty of our cross calibration is about 7.2% (k=2).
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HIROYUKI MURANAKA, OSAMU NAKAMURA, SHUJI USUI, YOSHITAKE UEDA, KAORU M ...
Article type: Article
2005 Volume 61 Issue 7 Pages
1014-1020
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It is increasingly the case that patients who have implants feel pain during high-field MRI examinations. A probable reason for the pain is the generation by irradiation of RF pulses and changing of the magnetic field gradient. As a fundamental study on the effect of implants on the human body under MRI procedures, temperature measurements were obtained from metal balls incorporated into gel-filled phantoms by using two kinds of measuring instruments, a copper-constantan thermocouple and a fluorescence fiber thermometer. At first we pursued a correlation between a copper-constantan thermocouple (absolute measurement) and fluoroptic thermometer and confirmed the precision and stability of the fluoroptic thermometer under MRI procedures. When a stainless steel ball with or without a loop antenna was used, only in the former case did the temperature rise during RF pulse irradiation. There was no significant difference between the magnetic field gradient ON and OFF. Furthermore, differences in metal (steel, aluminum, brass, stainless steel, copper) and size (5, 10, 20mmΦ) were affected according to the increase of temperature. In conclusion, both RF pulse irradiation and a loop antenna are necessary for heat generation on the surface of metals.
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EIJI NISHIMARU, RITSUKO UTSUNOMIYA, AKIFUMI NISHIE, YUUJI NINOMIYA, YU ...
Article type: Article
2005 Volume 61 Issue 7 Pages
1021-1026
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This paper proposes a new quantitative method of appraising the helical artifact generated by computed tomography (CT) images by helical scan. The quantities-appraisal method of the helical artifact uses as a sample image, the binarization image, which performs the threshold operation. Therefore, results may differ among observers and are lacking in objectivity. We devised a procedure (subtraction technique) that uses the subtraction process as a method of appraising the helical artifact that does not a perform a threshold operation, and evaluated this procedure. As compared with an area technique, a subtraction technique can divide a helical artifact into a plus CT value (Over Level) and a minus CT value (Under Level) and can evaluate them. This provides excellent repeatability and objectivity. Moreover, since CT value data are maintained, the quality of an artifact can also be evaluated, making this a very useful procedure. By using the subtraction technique, new information will be found by evaluating helical artifacts.
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YOSHIHISA TAKANO, KEIICHIRO OKAZAKI, KOJI ONO, MICHIAKI KAI
Article type: Article
2005 Volume 61 Issue 7 Pages
1027-1032
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Non-lead aprons using composite materials are often used for radiation protective aprons instead of heavy lead aprons. However, the protective effect of the lighter, non-lead aprons has not been well evaluated, and it is not yet clear how they compare with lead aprons. Therefore, we investigated the protective performance of non-lead aprons theoretically and experimentally by comparing them with lead aprons under clinical conditions. We measured the energy spectra for direct and scattered X-rays passing through protective aprons or not, and measured doses with glass dosimeters for validation of theoretical calculations based on the energy spectra. We found that the protective effect of non-lead aprons was higher than that of lead aprons at X-ray of tube voltages of 70-100kV, which are often used for radiography and fluorography. This demonstrated that the non-lead aprons are more useful in many situations than heavy lead aprons.
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TAKANORI HARA, KATSUHIRO ICHIKAWA, MASATOSHI TSUZAKA
Article type: Article
2005 Volume 61 Issue 7 Pages
1033-1039
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In this study, we processed reconstructed images with a new image filter(Siemens Medical Systems, Adaptive Image Filter^<TM>: AIF). As one of its characteristics, the filter uses low-pass filtering. When an image that emphasizes a high-frequency element is changed to one with a reduced high-frequency element, an image suitable for clinical use can be obtained. For the resolving characteristic and the noise characteristic, we evaluated the degree of transition, using the modulation transfer factor (MTF) and Wiener spectrum (WS). Moreover, we used the signal-to-noise ratio (SNR) to examine the total loss of signal detection capability after use of the AIF. The results showed that, when we changed to images using the AIF and made it the same level as B30 and U40, we had to hold down the kernel level to at least B60 and U80. The use of an image filter did not recognize less of an SNR in comparison with the reconstruction image. In this study, changes in detailed characteristics of the image and SNR could be evaluated objectively using the AIF. As for the effective method by AIF that raw data isn't used for is available for the control of an image (times) using reconstruction and the change of an image on database. Therefore, we consider the AIF useful to improve workflow in CT examinations.
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MOTOMICHI SAKATA, KUNIAKI HARADA, RYUJI SHIRASE, AKIKO KUMAGAI, MASASH ...
Article type: Article
2005 Volume 61 Issue 7 Pages
1040-1045
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The aim of our study was to optimize the parameters of high-resolution MRI of the labyrinth with a 3D-FSE sequence. We investigated TR, TE, Matrix, FOV, and coil selection in terms of CNR(contrast-to-noise ratio) and SNR(signal-to-noise ratio) by comparing axial images and/or three-dimensional images. The optimal 3D-FSE sequence parameters were as follows: 1.5 Tesla MR unit(Signa LX, GE Medical Systems), 3D-FSE sequence, dual 3-inch surface coil, acquisition time=12.08min., TR=5000msec, TE=300msec, 3 NEX, FOV=12cm, matrix=256×256, slice thickness=0.5mm/0.0sp, echo train=64, bandwidth=±31.5kHz. High-resolution MRI of the labyrinth using the optimized 3D-FSE sequence parameters permits visualization of important anatomic details (such as scala tympani and scala vestibuli), making it possible to determine inner ear anomalies and the patency of cochlear turns. To obtain excellent heavily T2-weighted axial and three-dimensional images in the labyrinth, high CNR, SNR, and spatial resolution are significant factors at the present time. Furthermore, it is important not only to optimize the scan parameters of 3D-FSE but also to select an appropriate coil for high-resolution MRI of the labyrinth.
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Yoshihiro Yamazaki
Article type: Article
2005 Volume 61 Issue 7 Pages
1046-
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
1047-1049
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
1050-1053
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
1057-
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
1058-
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Article type: Appendix
2005 Volume 61 Issue 7 Pages
1058-
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