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Article type: Cover
2004 Volume 60 Issue 8 Pages
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Article type: Index
2004 Volume 60 Issue 8 Pages
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Article type: Index
2004 Volume 60 Issue 8 Pages
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[in Japanese]
Article type: Article
2004 Volume 60 Issue 8 Pages
I-
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
II-IV
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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The Radiation Protection Section
Article type: Article
2004 Volume 60 Issue 8 Pages
1035-1038
Published: August 20, 2004
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HARUMI ITOH
Article type: Article
2004 Volume 60 Issue 8 Pages
1039-1044
Published: August 20, 2004
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MAKOTO YOKOFUJITA
Article type: Article
2004 Volume 60 Issue 8 Pages
1045-1049
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NAOYUKI KAIGE
Article type: Article
2004 Volume 60 Issue 8 Pages
1050-1058
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TAKAYUKI ISHIDA
Article type: Article
2004 Volume 60 Issue 8 Pages
1059-1064
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TAKAYUKI IGARASHI
Article type: Article
2004 Volume 60 Issue 8 Pages
1065-1071
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KOZO KUMAGAI, [in Japanese], [in Japanese], [in Japanese], [in Japanes ...
Article type: Article
2004 Volume 60 Issue 8 Pages
1072-1077
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ICHIRO YAMAGUCHI, [in Japanese], [in Japanese], [in Japanese], [in Jap ...
Article type: Article
2004 Volume 60 Issue 8 Pages
1078-1084
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JUNJI SHIRAISHI, [in Japanese], [in Japanese], [in Japanese], [in Japa ...
Article type: Article
2004 Volume 60 Issue 8 Pages
1085-1100
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MASAYUKI SHIMOSEGAWA
Article type: Article
2004 Volume 60 Issue 8 Pages
1101-1103
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SATOSHI OHNO
Article type: Article
2004 Volume 60 Issue 8 Pages
1104-1106
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HIDEKI KATO, SHIGEHISA FUJII, SHOICHI SUZUKI
Article type: Article
2004 Volume 60 Issue 8 Pages
1107-1115
Published: August 20, 2004
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Data on the percentage depth-dose of diagnostic X-rays are important in evaluating patient dose from medical exposure. We developed a new method of calculating central-axis depth-dose in a homogeneous tissue phantom irradiated by diagnostic X-rays. First, primary and scattered components of percentage depthdose for mono-energetic X-rays were calculated by means of Monte Carlo simulation, and the data were stored in data tables. Then, percentage depth-doses for individual X-rays were calculated by making use of the data tables, the photon spectrum of X-rays, and exposure conditions such as field size. This method, which can calculate depth-dose under any condition of irradiation by combining with the approximating equation of the X-ray spectrum, is useful in evaluating the percentage depth-dose of diagnostic X-rays.
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KEIICHI MATSUMOTO, YASUHIRO WADA, HAJIME MATSUURA, MICHIO SENDA
Article type: Article
2004 Volume 60 Issue 8 Pages
1116-1122
Published: August 20, 2004
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Objective: The noise equivalent count (NEC) is a useful, widely accepted method of evaluating image quality in positron emission tomography (PET) from the standpoint of effective count statistics. However, NEC cannot be used when different types of PET scanners are compared owing to the differences in slice thickness and field of view. Moreover, NEC should be treated differently depending on whether the 2D or 3D mode is used for a given PET scanner. A new parameter "Specific NEC," which is NEC per line of response (LOR) was devised to compare image quality between different PET scanners and acquisition modes. Methods: Two PET scanners were employed, the CTI-Siemens ECAT EXACT HR^+ and ECAT EXACT 47. Images of a cylindrical ^<68>Ge phantom were scanned in 2D and 3D modes using various acquisition times ranging from 15 sec×20 frames to 120 sec×20 frames in order to examine the effect of count statistics on the quality of image reconstruction. The data were reconstructed using a ramp filter with a cutoff frequency of 0.5 cycles/pixel, corrected for dead time, random, attenuation, and scatter. The quality of the reconstructed images was evaluated with the coefficient of variation (COV; SD/average for the pixels within a 16 cm region of interest). Specific NEC was defined as NEC divided by the number of LOR for the entire scanner at detector level. Results: COV showed a linear relationship with Specific NEC in double logarithmic plot within a given experiment. When the Specific NEC was used, all 2D and 3D mode showed the same relationship. The slight difference between the two scanners was attributed to the difference in slice thickness. Conclusion: Image quality was dependent on effective count statistics per number of LOR. Our method was considered effective for evaluating image quality in both 2D and 3D modes.
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MITSUO ISHIKAWA, TOSHINORI IDE, HIROSHI ASANO, ZIN SAGAWA, HIROYUKI MI ...
Article type: Article
2004 Volume 60 Issue 8 Pages
1123-1131
Published: August 20, 2004
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JIS Z 4910(anti-scatter grids) of the JIS standards was revised in 2000. Major points of revision were the provision of general-purpose and mammographic anti-scatter grids and changes in the diameter of the measuring field and difference in the manufacturing allowance. We measured the physical characteristics (grid selectivity, contrast improvement ratio, and grid exposure factor) of [general-purpose anti-scatter grids] referring to the methods of measurement[JIS Z 4910:2000] and [JIS Z 4910:1983]using an inverter-type high-voltage generator. Physical characteristics indicated a lower value for[JIS Z 4910:2000]than for[JIS Z 4910: 1983]. [JIS Z 4910:2000] was able to measure primary radiation and scattered radiation more accurately than[JIS Z 4910:1983] because of the diameter of the measuring field and the measurement arrangement. Moreover, the physical characteristic values were influenced by radiation quality, e.g., differences in high-voltage generators. In the method of measuring stipulated by JIS, strict conditions regarding the arrangement of the measurement tools and the stability and other factors of the power output of the X-ray generator are provided for the type approval test conducted by the manufacturer.
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SHINJI ABE, TORU NEGISHI, MASATO FUKAYA, TOSHIKAZU AKIYAMA, MASAYA NOG ...
Article type: Article
2004 Volume 60 Issue 8 Pages
1132-1138
Published: August 20, 2004
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Comparisons of focal-spot size measurements with a direct-exposure X-ray film, screen-film (S/F) system, and imaging plate (IP) were carried out for slit and star resolution pattern camera techniques. The focal-spot measurements of X-ray units with the nominal size of 0.1-1 mm were performed, and measurement using the computed radiography (CR) system was investigated. Compared with the direct-exposure X-ray film method, the measurements of focal-spot size by the S/F system were slightly small for all focal spots. The measurements obtained with IP were slightly large for large and small focal spots, although the measurement of micro focal-spot size was overestimated, extending the tolerance level owing to the sampling. With the star pattern camera technique, differences between the three kinds of detectors were minimal. Therefore, it was thought that measurement of focal-spot size using the CR system would be practical for both large and small focal spots if this method were used for quality control in medical facilities.
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TOSHIAKI GOTO, MASAHIRO OKA, SHIGEYUKI OOYA
Article type: Article
2004 Volume 60 Issue 8 Pages
1139-1142
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We assessed the usefulness of higher b values during diffusion-weighted imaging. When the b value was changed in a stepwise manner from 1000 s/mm^2 to 2000, and then 3000, the signal intensities of the region showing a high signal on the images were reduced by 39% and 55%, respectively. When they were compared with the intensities on the normal sides, they were increased by 29% and 40%, respectively, suggesting improvement in the detectability of cerebral infarction. The values of the apparent diffusion coefficient were reduced 15% and 31%, respectively. When they were compared with the values on the normal sides, the values were almost equivalent regardless of the b value.
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TAKAO ICHIDA, KENJI OKUSAKO, KOUJI YOKOYAMA, MASACHIKA SHOUGAKI, TAKAY ...
Article type: Article
2004 Volume 60 Issue 8 Pages
1143-1152
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We have been using an X-ray angiography system that incorporates a flat panel detector (FPD) since December 2001. This system is equipped with the scintillator-type FPD PaxScan 4030A from Varian Medical Systems, and for objective comparison of the image intensifier(l.I.)and FPD, the system is constructed so that these detectors can be used alternatively. Using this system and other X-ray angiography systems, visual studies have been conducted on the digital subtraction angiography (DSA) images acquired by FPD and I.I. We have found from the clinical images that the FPD is superior to the I.I. in depiction of fine blood vessels as well as of physical characteristics. Fluoroscopy images acquired by the FPD were not entirely satisfactory, however the improvement made in its performance now permits equal use of the FPD and I.I systems.
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
1153-1156
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
1159-1161
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Appendix
2004 Volume 60 Issue 8 Pages
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Article type: Cover
2004 Volume 60 Issue 8 Pages
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