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Article type: Cover
2001 Volume 57 Issue 11 Pages
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Article type: Index
2001 Volume 57 Issue 11 Pages
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Article type: Index
2001 Volume 57 Issue 11 Pages
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[in Japanese]
Article type: Article
2001 Volume 57 Issue 11 Pages
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Published: November 20, 2001
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Article type: Appendix
2001 Volume 57 Issue 11 Pages
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HITOSHI YOSHIMURA
Article type: Article
2001 Volume 57 Issue 11 Pages
1275-1282
Published: November 20, 2001
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AKIRA OTSUKI
Article type: Article
2001 Volume 57 Issue 11 Pages
1283-1290
Published: November 20, 2001
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HIROMU MIKI
Article type: Article
2001 Volume 57 Issue 11 Pages
1291-1297
Published: November 20, 2001
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MASAHIRO YOSHIMOTO
Article type: Article
2001 Volume 57 Issue 11 Pages
1298-1302
Published: November 20, 2001
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HIROSHI FUJITA
Article type: Article
2001 Volume 57 Issue 11 Pages
1303-1309
Published: November 20, 2001
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Takeshi Hara
Article type: Article
2001 Volume 57 Issue 11 Pages
1310-1315
Published: November 20, 2001
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Junji Shiraishi, Shigehiko Katsuragawa
Article type: Article
2001 Volume 57 Issue 11 Pages
1316-1324
Published: November 20, 2001
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YOSHIHIKO KAWAMURA
Article type: Article
2001 Volume 57 Issue 11 Pages
1325-1332
Published: November 20, 2001
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MASAYUKI SHIMOSEGAWA
Article type: Article
2001 Volume 57 Issue 11 Pages
1333-1338
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MASAHIKO OKUMURA
Article type: Article
2001 Volume 57 Issue 11 Pages
1339-1348
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SHINOBU ASAHAWA
Article type: Article
2001 Volume 57 Issue 11 Pages
1349-1351
Published: November 20, 2001
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FUTORU YANO
Article type: Article
2001 Volume 57 Issue 11 Pages
1352-1355
Published: November 20, 2001
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YASUSHI YAMAMOTO, SHINOBU TAKAHASHI, AKIO KOMATSU, NOBUE UCHIDA, HIROK ...
Article type: Article
2001 Volume 57 Issue 11 Pages
1357-1364
Published: November 20, 2001
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GAF Chromic Dosimetry Media(GAF Media, Nuclear Associates Co.Ltd.)has been newly developed for the purpose of absorbed dose measurements with ionizing radiation. GAF Media is colorless and transparent before radiation exposure, and it changes progressively to a darker blue color with exposure. In contrast to conventional film, GAF Media can be used in room light and does not require any other procedure to develop or fix the image. In this study, we used a microdensitometer to evaluate the relationship between the absorbed dose and optical density of GAF Media types MD-55 and HD-810. We discuss the possibility of application of GAF Media as a simple dosimeter of percent depth dose(PDD)and off-center ratio(OCR) in the field of quality assurance(QA)of radiotherapy. The optical density derived by GAF Media could be converted into absorbed dose by using an approximation curve. However, the elevation of baseline density, the "fog effect", according to time was too great to be neglected. To measure the absorbed spectrum of GAF Media a microdensitometer attached with a Band Pass Filter, which selectively absorbed the spectrum at 671 nm, was useful. The PDD and OCR curves derived by GAF Media were accurate enough for QA of radiotherapy. GAF Media was simple to use, but further investigation will be required before applying it in other fields.
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HIDEO OHNISHI, TADAYUKI IIDA, SATORU MATSUO, TETSUO KIDA, MASAHIRO YOS ...
Article type: Article
2001 Volume 57 Issue 11 Pages
1365-1371
Published: November 20, 2001
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We evaluated the optimal number of iterations on maximum likelihood-expectation maximization (MLEM) reconstruction algorithm in SPECT images using four methods: full width at half maximum (FWHM), statistical noise, edge recovery of image (recovery coefficient; RC), and normalized mean squared error (NMSE). We acquired SPECT images using 99m-Tc as a signal source for three phantoms: a line source phantom, uniform cylinder, and hot rod phantom. The line source phantom was used to measure reconstructed image resolution; the uniform cylinder phantom was used to evaluate statistical noise and image recovery; and the hot rod phantom was used to evaluate the NMSE method. We varied acquisition time as follows: 300 sec/step, 30 sec/step, and 5 sec/step, and numbers of iterations of ten times and more. Statistical noise converged early at 50 iterations for acquisition time for 300 sec/step. The RC value neared 1.0 for 300 sec/step, but remained at 0.7 for 30 sec/step and 5 sec/step. The optimal number of iterations was 50 for images obtained with the high frequency ingredient with 30 sec/step and 30 for images obtained with low frequency. The number of iterations should be changed according to acquisition time and the frequency ingredient contained in images.
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JUN KOHNO, MASAKO ITO, MIKA KOHNO, TOMOKO NAKATA, KIYOTAKA FURUYAMA, T ...
Article type: Article
2001 Volume 57 Issue 11 Pages
1372-1379
Published: November 20, 2001
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Human iliac trabecular bone specimens were scanned using micro-computed tomography to obtain volume data of two-dimensional images in post-menopausal women, and two- and three-dimensional morphometric parameters, such as trabecular bone volume/tissue volume, trabecular thickness, structure model index, and trabecular bone pattern factor, were calculated using these image data. We developed several image processing programs for fast, easy operation. The contents of the image processing programs include changing of image resolution and image size, thresholding value, filtering, labeling, and division into elements. Several processings of the same image data were performed for the finite element analysis(FEA). Based on results of the degree of anisotropy, the bone structure was loaded in three directions, x-, y-, and z-axes. The images of the stress distribution and yield strength obtained from the three axis directions differed depending on load direction, and the correlations of yield strength with the variousmic rostructural parameters also differed depending on load direction. Load direction in vivo should be considered for bone specimens in FEA analysis.
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YASUNOBU KAMEYAMA, NORIKO MITSUE, SHIGEHIKO SATO, KIMIHIKO KATO, MASAY ...
Article type: Article
2001 Volume 57 Issue 11 Pages
1380-1386
Published: November 20, 2001
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The aim of this study was to assess the clinical significance and validity of the advanced quantitative 201-Tl and 99m-Tc gated SPECT (QGS-A)methods. We studied 79 patients(48 men, 31 women; mean age 70±14 yr)with cardiomyopathy(n=4)and ischemic(n= 57)or congestive heart disease(n=18). Methods: All subjects were investigated as to the correlation between values with QGS-A and UCG. Either 201-Tl(n=51)or 99m-Tc(n=28)gated SPECT was performed at rest(n=48)or stress(n=3l)stage followed by UCG within one month. Gated SPECT data, including EDV, ESV, and LVEF, were quantified by using an automatic algorithm as QGS-A, whereas UCG data(EDV, ESV, and LVEF)were determined by the standard technique. Results: A significant correlation was found between 201-Tl or 99m-Tc QGS-A and UCG with respect to EDV, ESV, and LVEF(201-Tl: r=0.761, 0.882, 0.819; 99m-Tc: r=0.515, 0765, 0695, respectively, all p values < 0.01), regardless of the use of rest images. The mean values of EDV, ESV, and LVEF calculated by QGS-A were significantly lower than those of UCG(all p values <0.01). Conclusion: LV volumes and LVEF calculated by both 201-Tl and 99m-Tc QGS-A were significantly correlated with those obtained by UCG. These findings support the clinical significance and validity of 201-Tl and 99m-Tc QGS-A for simultaneously assessing both LV function and myocardial perfusion imaging.
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ISAO MIYAZAKI, SHINJI KIUCHI, YASUSHI MARUYAMA, HIROSHI TAKEUCHI, KUNI ...
Article type: Article
2001 Volume 57 Issue 11 Pages
1387-1394
Published: November 20, 2001
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Magnetic resonance angiography(MRA)with contrast medium is increasingly being used in examination of the abdomen, pelvis, and lower limbs. However, angiography at opposed phase causes paradoxical suppression(PS)due to the higher fat content of these areas. We evaluated the effect of PS on the ability to visualize blood vessels. The items evaluated included the effect of contrast medium concentration and TE(echo time)on PS as well as a comparison of fat suppression with the subtraction technique by referring to a mock blood vessel and pictures obtained by subjecting volunteers to MRA with contrast medium. Shorter TE and higher concentrations of contrast medium both reduced PS. The ability to visualize blood vessels was reduced by the subtraction technique, as compared with fat suppression. In clinical studies, fat suppression is essential. Hence, when MRA with contrast medium is performed with an apparatus or at a site where fat suppression is not feasible, PS must be taken into account to establish parameters.
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SACHIKO KOGA, SHINSUKE YANO, TAKASHI OKADA, SYUNJI KAWANO, HIROYUKI AK ...
Article type: Article
2001 Volume 57 Issue 11 Pages
1395-1405
Published: November 20, 2001
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Kyoto University Hospital has recently introduced a stereotactic body frame(SBF)for radiotherapy for lung tumors. Twenty-one patients were treated between July 1998 and March 2000 at Kyoto University Hospital for solitary pulmonary nodules. The study was performed to evaluate the feasibility of three-dimensional(3D)conformal radiotherapy for a solitary lung tumor using the SBF. The clinically applicable range of the beam direction was mapped to avoid collisions between the gantry, couch, and the SBF prior to its clinical application. After mapping the beam direction range, 3D conformal radiotherapy using the SBF was carried out. The SBF has a fixed thickness. The irradiation dose has been absorbed by the SBF, and the target reference dose has been somewhat attenuated. Therefore, we measured dose attenuation in the direction of the beam relative to the SBF. The average percentage of dose attenuation was 9.3%. The precision of setting a target reference dose in stereotactic radiotherapy is important clinically. As a result, a correction factor of 9.3% was used, and a comparison between the absence of a recent planning dose and the presence of a recent planning dose was performed. Furthermore, treatment planning using a chest phantom was carried out, and the target reference dose was compared using a dosimeter. It is thought that the correction method evaluated in this study is needed for precise control of the target reference dose.
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HIROYA KUBO, MOTOKI USUl, KENICHI FUKUNAGA, NARUTO YAMAMOTO, TOSHIMI I ...
Article type: Article
2001 Volume 57 Issue 11 Pages
1406-1411
Published: November 20, 2001
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The single shot fast spin echo single thick slice method(single slice method)is a technique that visualizes the water component alone using a heavy T_2. However, this method is considered to be markedly affected by changes in the viscosity of the material because a very long TE is used, and changes in the T_2 value, which are related to viscosity, directly affect imaging. In this study, we evaluated the relationship between the effects of TE and the T_2 value of bile in the single slice method and also examined the relationship between the signal intensity of bile on T_1- and T_2-weighted images and imaging by MR cholangiography(MRC). It was difficult to image bile with high viscosities at a usual effective TE level of 700-1, 500 ms. With regard to the relationship between the signal intensity of bile and MRC imaging, all T_2 values of the bile samples showing relatively high signal intensities on the T_1-weighted images suggested high viscosities, and MRC imaging of these bile samples was poor. In conclusion, MRC imaging of bile with high viscosities was poor with the single slice method. Imaging by the single slice method alone of bile showing a relatively high signal intensity on T_1-weighted images should be avoided, and combination with other MRC sequences should be used.
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Tetsuro Katafuchi
Article type: Article
2001 Volume 57 Issue 11 Pages
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Kenichi Hirako
Article type: Article
2001 Volume 57 Issue 11 Pages
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[in Japanese]
Article type: Article
2001 Volume 57 Issue 11 Pages
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Article type: Appendix
2001 Volume 57 Issue 11 Pages
1415-1417
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Article type: Appendix
2001 Volume 57 Issue 11 Pages
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Article type: Appendix
2001 Volume 57 Issue 11 Pages
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Article type: Appendix
2001 Volume 57 Issue 11 Pages
1419-1422
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Article type: Appendix
2001 Volume 57 Issue 11 Pages
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Article type: Appendix
2001 Volume 57 Issue 11 Pages
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Article type: Cover
2001 Volume 57 Issue 11 Pages
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