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Article type: Cover
2003 Volume 59 Issue 11 Pages
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Article type: Cover
2003 Volume 59 Issue 11 Pages
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Article type: Index
2003 Volume 59 Issue 11 Pages
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Article type: Index
2003 Volume 59 Issue 11 Pages
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[in Japanese]
Article type: Article
2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
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Hiroshi Fujita
Article type: Article
2003 Volume 59 Issue 11 Pages
1327-1337
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JUNJI MORISHITA, [in Japanese]
Article type: Article
2003 Volume 59 Issue 11 Pages
1338-1339
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KUNIO DOI
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2003 Volume 59 Issue 11 Pages
1339-1343
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TOKIKO ENDO
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2003 Volume 59 Issue 11 Pages
1343-1344
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KIYOSHI NAMBA
Article type: Article
2003 Volume 59 Issue 11 Pages
1345-1347
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HIROSHI FUJITA
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2003 Volume 59 Issue 11 Pages
1347-1349
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SUZUSHI KUSANO
Article type: Article
2003 Volume 59 Issue 11 Pages
1349-1351
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HIDEYKI WATANABWE, [in Japanese], [in Japanese], [in Japanese], [in Ja ...
Article type: Article
2003 Volume 59 Issue 11 Pages
1352-1354
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KAZUTO ASHIZAWA
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2003 Volume 59 Issue 11 Pages
1354-1357
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SHIGEHIKO KATSURAGAWA
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2003 Volume 59 Issue 11 Pages
1358-1360
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TAKURO SAITO
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2003 Volume 59 Issue 11 Pages
1361-1369
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TOSHIO TSUCHIHASHI
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2003 Volume 59 Issue 11 Pages
1370-1377
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YOSHIE KODERA
Article type: Article
2003 Volume 59 Issue 11 Pages
1378-1381
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YASUHIKO TOHYAMA
Article type: Article
2003 Volume 59 Issue 11 Pages
1382-1385
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CHUDO KAZUSA
Article type: Article
2003 Volume 59 Issue 11 Pages
1386-1389
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TAKANORI HARA, MASATOSHI TSUZAKA, NAOYUKI SAKURAI
Article type: Article
2003 Volume 59 Issue 11 Pages
1391-1398
Published: November 20, 2003
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Many methods of measuring the section-sensitive profile (SSP) of computed tomography (CT) by the input of a delta function have been reported. In Japan, the bead method is used as a common measurement because of the high flexibility of the multi-purpose method. However, the intensity of the response of the bead method tends to decline, creating a relatively large error in the base of section-sensitive profiles. A problem is considered to be the accuracy of measurement in evaluating spatial resolution along the z-axis in multi-slice spiral/helical CT (MSCT). We therefore evaluated the modulation transfer function (MTF) by conducting research with the micro-disk method (100 μm thickness and 1.0 mmφ diameter)and the bead method (1.0 mmφ diameter) for the same input width. Moreover, in the micro-disk method, we also examined alignment, circular regionof interest (ROI) , and the energy characteristic. Our comparison of MTFs obtained by the micro-disk method and the bead method showed that the former resulted in a higher value and lower standard deviation. The difference was significant at p<0.01. Measurement using the micro-disk method did not show significant differences in terms of alignment and ROIs. Moreover, the energy characteristic was not indicated. This research demonstrated that the accuracy of MTF measurement with the micro-disk method was greater than that with the bead method, and it was found that there was no influence on the actual measurement level of the geometric structure with the micro-disk method.
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KAZUSHIGE YODA, TOKUO UMEDA, TOMOYUKI HASEGAWA
Article type: Article
2003 Volume 59 Issue 11 Pages
1399-1406
Published: November 20, 2003
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Organ movements that occur naturally as a result of vital functions such as respiration and heartbeat cause deterioration of image quality in nuclear medicine imaging. Among these movements, respiration has a large effect, but there has been no practical method of correcting for this. In the present study, we examined a method of correction that uses ultrasound images to correct baseline shifts caused by respiration in cardiac nuclear medicine examinations. To evaluate the validity of this method, simulation studies were conducted with an X-ray TV machine instead of a nuclear medicine scanner. The X-ray TV images and ultrasound images wererecorded as digital movies and processed with public domain software (Scion Image). Organ movements weredetected in the ultrasound images of the subcostal four-chamber view mode using slit regions of interest and were measured on a two-dimensional image coordinate. Then translational shifts were applied to the X-ray TV images to correct these movements by using macro-functions of the software. As a result, respiratory movements of about 20.1 mm were successfully reduced to less than 2.6 mm. We conclude that this correction technique is potentially useful in nuclear medicine cardiology.
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NORIO HAYASHI, SHIGERU SANADA, MASAYUKI SUZUKI
Article type: Article
2003 Volume 59 Issue 11 Pages
1407-1413
Published: November 20, 2003
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Brain MRI is an important method for examining the diseases caused by various cerebral pathologies, and the measurement of temporal lobe volume is useful for identifying dementia and temporal lobe abnormalities. However, no segmentation algorithm for the temporal lobe on coronal MR images has been established. Such an algorithm is needed because the shape of the temporal lobe on coronal images varies from area to area. The purpose of this research was to develop a segmentation method for the posterior portion of the temporal lobe on coronal MR images. The subjects were 11 normal patients, whose coronal Ti-weighted images were selected for this study. The preprocessing algorithm for segmentation consists of smoothing, binarization, and thinning. The first step of the segmentation process consists of recognition techniques for the temporal lobe region on thinning images. The next step is distance transformation on identified thinning images. Finally, the temporal lobe was segmented by using the original images and distance transformation images and employing the newly developed algorithm. The rate of accuracy of automated recognition was over 74% for all cases, while the average rate of accuracy was 83.2±4.0%. These results suggest that this segmentation method can clearly segment the temporal lobe and has potential for clinical use. Based on this study, although it included only 1 1 normal patients, we have started applying this segmentation method to many patients, with or without temporal lobe disease.
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MITSURU ICHIHARA, YUKI NAKAMURA, TOMOHIKO OKAWA
Article type: Article
2003 Volume 59 Issue 11 Pages
1414-1423
Published: November 20, 2003
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We examined the usefulness of proton magnetic resonance spectroscopy (^1H-MRS) for imaging diagnosis in 50 outpatients and 42 emergency patients with hyperacute ischemic brain disease. In hyperacute ischemic brain disease, a reduction of N-acetylaspartate and the appearance of lactate were found in the spectrum from immediately after the development of symptoms. Thereafter, a decrease in N-acetylaspartate and increase in lactate was observed with time, and the pattern of the spectrum was categorized. Moreover, evaluation of the penumbra was considered, including its relation with the intra-arterial signal as determined by the T_2 fluid-attenuated inversion recovery image of magnetic resonance imaging. Our results obtained from the use of proton MR spectroscopy to perform cerebral evaluation on a cellular level were examined by evaluation of the ischemic penumbra of an ischemic brain disease, and were considered to be useful.
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MASATOSHI HASHIMOTO, KIYOYUKI KODAMA, TAKASHI HANADA, TATSUYA IDE, TOM ...
Article type: Article
2003 Volume 59 Issue 11 Pages
1424-1431
Published: November 20, 2003
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We propose a new method to measure the depth dose distribution in matter. The method is to use organic plastic scintillator as a phantom, which has the effective atomic number close to that of human soft tissue, and to measure the position distribution of the scintillation light by a wavelength analyzer through a thread of plastic optical fiber. The purpose of this study is to examine possibility to measure the depth dose distribution with the proposed method. We carried out the following three measurements. First, we measured the effective field of view (FOV); the plastic optical fiber accepts the light from the FOV. Then, we measured the dose dependence of the amount of emission light. Finally, the light distribution in the depth direction by the present method was compared to the depth dose distribution by the ionization chamber. The results are as follows. The angular range of FOV is 7.03°±0.21°. The dose dependence shows a good linearity. In other words, the amount of emission light is proportional to the absorbed dose. Both of the light and the dose distributions are proportional each other, and they show the same attenuation in the region deeper than 15 mm. From these results, we conclude that the present method can be used for the measurement of the depth dose distribution in matter.
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NORIYA YOKOHAMA, GO KAGIYA, ICHIRO MARUYAMA, AKIHIKO NISHIJIMA, KAZUTA ...
Article type: Article
2003 Volume 59 Issue 11 Pages
1432-1437
Published: November 20, 2003
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Exact reproducibility of patient positioning is a critical issue for proton therapy because of the sharp dose distribution. We constructed the first proton therapy system with a common couch for both CT and proton irradiation. In this paper, we report a brief overview of the instruments and the accuracy of mechanical positioning reproducibility.
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SIGENOBU SEGUCHI, YOSHINOBU ISHIKAWA, SHOUTA MIZUNO, TAKAYA SAIJOU, TA ...
Article type: Article
2003 Volume 59 Issue 11 Pages
1438-1443
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We compared the INNOVA2000(INNOVA) , which has a flat panel detector system, and the Advantx LCLP(LCLP), which has a conventional I. I. system, in terms of the dependence of phantom thickness on patient surface dose (surface dose)and receptor entrance dose (entrance dose). We examined the reduction in surface dose and entrance dose by using an additional filter and shortening the patient detector distance (PDD). The surface dose rate for fluoroscopy with INNOVA was 73.8〜63.5%, and the reduction rate was high at a phantom thickness of less than 20 cm compared with LCLP, but such a reduction could not be expected at a phantom thickness of more than 30 cm, depending on maximum dose rate. The rate of reduction in surface dose in the case of exposure was considerrably low at a phantom thickness of about 20 cm, while the other's (5, 10, 15, 25, 30 cm)reduction rates were about 40%. The length of PDD with INNOVA was shortened by 5 cm compared with LCLP. As a result, we obtained a reduction rate of surface dose of 11〜15%, while the entrance dose was 10% lower. The reduction rate achieved with an additional filter was 43〜60% in surface dose rate in fluoroscopy, whereas that of surface dose for exposure was about 50% at phantom thicknesses up to 20 cm, but remained just 25% thereafter. The results indicated that the reduction of surface dose with INNOVA could be changed by means of the phantom thickness, and we consider the effect achieved by the addition of a filter to be the main factor.
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
1444-1446
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Article type: Appendix
2003 Volume 59 Issue 11 Pages
1447-1448
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2003 Volume 59 Issue 11 Pages
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Article type: Cover
2003 Volume 59 Issue 11 Pages
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