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Article type: Cover
1998 Volume 54 Issue 5 Pages
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Article type: Cover
1998 Volume 54 Issue 5 Pages
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Article type: Index
1998 Volume 54 Issue 5 Pages
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Article type: Index
1998 Volume 54 Issue 5 Pages
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[in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
I-
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Article type: Appendix
1998 Volume 54 Issue 5 Pages
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Article type: Appendix
1998 Volume 54 Issue 5 Pages
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1998 Volume 54 Issue 5 Pages
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Article type: Appendix
1998 Volume 54 Issue 5 Pages
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HIDEKI KATO, MASATOSHI TSUZAKA, SHUJI KOYAMA, HISASHI MAEKOSHI
Article type: Article
1998 Volume 54 Issue 5 Pages
615-623
Published: May 20, 1998
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An x-ray spectrum measured by a semiconductor detector is different from the incident x-ray spectrum to the detector, because of distortions caused by energy-dependent responses of the detector and statistical and electrical fluctuations in the signal amplifying process. In this paper, we discuss a method for correcting the statistical and electrical fluctuations of the x-ray spectrum, using the unfolding method with a function based on the Gaussian distribution. Unfolding the measured x-ray spectrum by this method, K-α and K-β characteristic x-rays were clearly separated into two line spectra, and energy resolution was improved. The unfolding method, when used to supplement the stripping method that is generally applied to x-ray spectra correction, will provide enhanced correction of x-ray spectra.
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JOJI KATO, YOSHIHIKO KAWAMURA
Article type: Article
1998 Volume 54 Issue 5 Pages
624-629
Published: May 20, 1998
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Contrast MRA obtained through the combined use of the spectral selective inversion pulse and enhanced three-dimensional fast spoiled gradient echo method was examined for imaging conditions. The results of simulation revealed the highest blood signal value at an FA of 30 degrees. The signal intensity of fat with the combined use of the spectral selective inversion pulse and three-dimensional fast spoiled gradient echo method were shown to very with TI and the FA of the enhanced three-dimensional fast spoiled gradient echo method. The bounce point for fat became shorter as FA increased, and it was prolonged for smaller FA. It is important with the present method to adjust TI such that a fat suppressant effect is obtained after setting an FA that will provide the highest blood signal value. The optimization of FA and TI led to good MRA performance with a clinically significant decrease in the fat signal.
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MASAMICHI YANAGISAWA, FUJIMI KINOSHITA, MIKA MORISADA, HIRONORI ICHIHA ...
Article type: Article
1998 Volume 54 Issue 5 Pages
630-638
Published: May 20, 1998
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Three photopeaks are generally used to obtain tumor images with gallium-67. However, in this situation, images are affected by scattered photons from high energy fractions. Therefore, we applied the triple energy window(TEW) method to correct for scattered gamma-ray and improve the quality of images. A low-energy general-purpose(LEGP) collimator was used in consideration of the total balance of resolution and sensitivity of the collimator, and photopeaks of 93 keV and 185 keV were measured. With the low-energy collimator, the influence of compton scatter, which penetrates collimators of higher energy than Ga-67, was strong. Therefore, the distance from the source to the collimator needed to be 3 meters or more when the photopeak was set using the LEGP collimator. Background count was decreased by the correction of compton scatter. FWHM and contrast improved 4.8 mm and 14.8%, respectively, and clearer images could be obtained using the LEGP collimator with scatter correction than with the usual MEGP collimator without scatter correction. However, the anatomical localization of the lesion became less clear because the background count was decreased, especially in SPECT. Addition of the TCT image clarified the anatomical localization of the lesion.
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SEIJI SHIRAKAWA, TORU FUZITA, NAGARA TAMAKI, JYUNJI KONISHI, SUKEHIRO ...
Article type: Article
1998 Volume 54 Issue 5 Pages
639-645
Published: May 20, 1998
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In the quantitative analysis of SPECT images, it is necessary to correct for attenuation, scatter, and partial volume effect. Attenuation correction of a non-uniform body was possible with a simultaneous transmission-emission protocol(STEP). Scatter correction was also possible with the triple energy window(TEW) method. We evaluated the quantitative distribution of a Pei phantom and a cardiac-thoracic phantom using STEP and the TEW method. This system consists of a Tc-99m line source assembly and triple-head SPECT system(PRISM3000, Picker Int.) with cardio fan beam collimators. The uniformity of the tracer distribution on a Bull's-eye map was quantitatively evaluated as C.V. value in non-correction, STEP, and the combined correction protocol. Without activity in the liver, the C.V. value was improved from 8.9% to 5.58% with STEP. When liver activity was set beneath the cardiac phantom, the activity was not uniform with STEP, but it became uniform with the combined correction protocol. In conclusion, accurate correction of attenuation and scatter can be performed with the combined correction protocol. This protocol holds promise for the quantitative measurement of tracer concentration on SPECT images.
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TOSHIO TSUCHIHASHI, SATOSHI YOSHIZAWA, TOSHIO MAKI, ISAO FUZITA, TAKES ...
Article type: Article
1998 Volume 54 Issue 5 Pages
646-652
Published: May 20, 1998
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A basic investigation was carried out regarding the spectrally selected inversion recovery pulse(Spce IR) that affects fat suppression using the fat selective inversion pulse. As this has been used for MR angiography(MRA), we are reporting on it. Spec IR is able to affect fat suppression without a significant increase in repetition time(TR) as inversion pulses are used for each change in phase encoding. Inversion time(TI) and flip angle(FA) settings were important for the fat suppression effects. Inversion pulses are only used for each change in phase encoding, so if the number of slices is increased(number of slice encodings is increased), fat suppression decreases. This problem could be solved by reducing the number of slices without reducing spatial resolution through the use of zero-filled interpolation(AIP) in the slice direction. In MRA that uses Spce IR, the extraction of small vessels that may be concealed in fat within the abdominal arteries and pelvic arteries has been improved, which is an indication that fat is suppressed.
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OSAMU FUJITA, MOTOHIRO ARAI, KATSUNORI FUKUMURA, YOSHITO SUGINOBU, MAS ...
Article type: Article
1998 Volume 54 Issue 5 Pages
653-662
Published: May 20, 1998
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In this study, we established imaging, construction, and presentation methods for three-dimensional images for surgical simulation of cerebral tumors. Three-dimensional images were produced from head volume data obtained using an MR instrument, and the usefulness of three-dimensional images for surgical simulation was examined. Using the function of three-dimensional image processing in an independent-type diagnostic workstation(Advantage Windows, GE Inc.), three-dimensional images for surgical simulation of several patients with cerebral tumors were produced by the volume-rendering method. The quality of the three-dimensional images of the head obtained by this method was high, indicating the usefulness of three-dimensional images for surgical simulation of cerebral tumors. However, since manual treatment was still required for segmentation, several problems such as long image treatment time remained.
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TOSHIMITSU SATO, YOICHI EGUCHI, AKIO OKADA, HITOSHI KIMURA, TETSUO TOS ...
Article type: Article
1998 Volume 54 Issue 5 Pages
663-670
Published: May 20, 1998
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In angiographic systems, interventional radiology(IVR) results in a relatively high radiation dose to the patient and staff due to the extended fluoroscopy time and number of images acquired during an examination. In this study, entrance exposure dose to I.I. and entrance surface exposure dose were measured in 18 angiographic systems at 15 hospitals. The average entrance exposure dose was 1.77 μC/kg/min(1.10-3.38) with the continuous fluoroscopic mode, 2.02 μC/kg/min(1.10-4.02) with the pulsed fluoroscopic mode(30pulse/sec), 1.06 μC/kg/min(0.66-2.11) with the pulsed fluoroscopic mode(15 pulse/sec), 7.96 nC/kg/frame(4.26-16.8) with the cine and DA simultaneous acquisition, and 6.40 nC/kg/frame(3.12-12.5) with the DA acquisition. The average entrance surface exposure dose was 0.86 mC/kg/min(0.52-1.47) with the continuous fluoroscopic mode, 0.99 mC/kg/min(0.57-1.40) with the pulsed fluoroscopic mode(30 pulse/sec), 0.51mC/kg/min(0.29-0.72) with the pulsed fluoroscopic mode(15 pulse/sec), 5.74μC/kg/frame (2.19-9.80) with the cine and DA simultaneous acquisition, and 4.64 μC/kg/frame (1.60-7.48) with the DA acquisition. the x-ray tubes, additional dose reduction filters and x-ray grids obviously influenced the results of entrance surface exposure dose.
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TSUKASA DOI
Article type: Article
1998 Volume 54 Issue 5 Pages
671-672
Published: May 20, 1998
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YASUTOMI KINOSADA
Article type: Article
1998 Volume 54 Issue 5 Pages
672-677
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YUKINORI YAMADA
Article type: Article
1998 Volume 54 Issue 5 Pages
677-680
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TSUYOSHI MATSUDA
Article type: Article
1998 Volume 54 Issue 5 Pages
680-683
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KATSUTOSHI MURATA
Article type: Article
1998 Volume 54 Issue 5 Pages
683-686
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[in Japanese], [in Japanese], KAZUO AWAI, [in Japanese], [in Japanese] ...
Article type: Article
1998 Volume 54 Issue 5 Pages
687-696
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YASUHIRO HIAI
Article type: Article
1998 Volume 54 Issue 5 Pages
697-701
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TOMISAKU KAWASAKI
Article type: Article
1998 Volume 54 Issue 5 Pages
702-706
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[in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
707-708
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[in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
709-712
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[in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
713-714
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Article type: Bibliography
1998 Volume 54 Issue 5 Pages
715-716
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Article type: Appendix
1998 Volume 54 Issue 5 Pages
717-718
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1998 Volume 54 Issue 5 Pages
719-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
720-
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[in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
720-
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[in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
720-
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[in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
720-
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[in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
720-
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[in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
720-
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[in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
720-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
720-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
720-721
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Article type: Article
1998 Volume 54 Issue 5 Pages
721-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
721-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
721-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
721-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
721-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
721-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
721-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
721-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
721-
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
721-722
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[in Japanese], [in Japanese]
Article type: Article
1998 Volume 54 Issue 5 Pages
722-
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