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Article type: Cover
1988 Volume 44 Issue 10 Pages
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Article type: Index
1988 Volume 44 Issue 10 Pages
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Article type: Index
1988 Volume 44 Issue 10 Pages
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Article type: Appendix
1988 Volume 44 Issue 10 Pages
i-iii
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Article type: Appendix
1988 Volume 44 Issue 10 Pages
iv-v
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Article type: Appendix
1988 Volume 44 Issue 10 Pages
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MASAO FUNAHASHI, KAZUHIRO MIHARA, TOSHIROU SHIMAZAKI, KATSUHITO ABE, K ...
Article type: Article
1988 Volume 44 Issue 10 Pages
1472-1480
Published: October 01, 1988
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Regarding chest radiograph imaging, the density is distributed only in the two extremities, the high-density area mainly of the lungs and the low-density area mainly of mediastina. This is the feature of the image quality of chest radiographs which requires special attention in evaluating images. For each density area, we devised and examined the methods of selecting the film-screen system best suited to chest radiography. The experiments were carried out respectively with the sharpness in the high density area, the visual detectability of low-contrast signals in low density area and the condition of granularity when a photographic subject is used (Figs. 3 and 6). As a result of our experiments, radiographic image is affected by the film's own sharpness while the thickness of the subject is small. With the increase in the thickness, however, it is affected by the toe's form of the H&D curve. In this study, it was recognized that simulation experiments based on the examination of the subject in question is essential prior to the immediate advance from physical data to clinical radiographs.
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TOMOHIKO HATTORI, TADASHI TAMIYA, TSUKASA WATANABE
Article type: Article
1988 Volume 44 Issue 10 Pages
1481-1485
Published: October 01, 1988
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In this paper the approximate analytic formula of stereoscopic capability and characteristics of distortion for the three-dimensional seen by stereography is compared with the experimental data concerning X-ray linear tomography. The stereoscopic capability about parallax of eyes can be explained by only simple parameter dγ which is half value of parallax between eyes. It is also suggested that the utility of stereoscopic tomography.
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HIDEKI KATO
Article type: Article
1988 Volume 44 Issue 10 Pages
1486-1491
Published: October 01, 1988
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A Monte Carlo computer program has been used to analyze the characteristics of each order of scattered radiation in a phantom irradiated by <60>^Coγ-rays and 10 MV X-rays. The program simulated an irradiation with a pencil beam upon a center of 30×30×30 cm water phantom and calculated the primary doses and each order of scattered doses on the beam axis of circular fields from the simulation data. Relative fraction of first scattered doses to full scattered doses did not change so much with a change in depth, and could be approximated as a function of field radius only. When full scattered doses, which calculated by this approximating equation using first scattered doses, were used on the correcting equation of an inhomogeneous medium, the correction factors deviated from that calculated using the true value of full scattered dose with less than I percent on average. Using this approximating equation, the inhomogeneous correction factors, which take in account of full scattered doses, could be calculated briefly by means of the first scattered doses.
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KAZUMI KANAI, AKIYOSHI OHTSUKA, JUNJI MORISHITA, SYUICHI YAMAUCHI, KAT ...
Article type: Article
1988 Volume 44 Issue 10 Pages
1492-1496
Published: October 01, 1988
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The "DSA characteristic curve" is the most important factor in evaluating the physical performance in digital subtraction angiography(DSA) systems, and is expressed as output DSA pixel value to input relative X-ray intensity. In this study, utilizing the DFA-II system, three methods were compared in measuring characteristic curves : (1) the aluminium step-wedge method ; (2) inverse-square method ; and (3) time-scale method. In the aluminium step-wedge method, a fluorescence meter and a film-screen system were employed as detectors to determine relative X-ray intensity. Results indicated that the characteristic curves measured by the three methods were almost identical and had very few errors. In the three methods, the time scale method was the most useful for the DFA-II system due to its simplicity and accuracy.
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SADAMITSU NISHIHARA, AKIYOSHI OHTSUKA, MASAHIRO HASHIDA, SYUICHI YAMAU ...
Article type: Article
1988 Volume 44 Issue 10 Pages
1497-1504
Published: October 01, 1988
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We investigated the differences in image contrast caused by intensifying screens. Five commercial screens with different phosphors and three kinds of objects were used in this experiment. A fluorescence meter was employed as a detector to measure the characteristics of screens only. Object's attenuation curves were measured to calculate the image contrast. As a result, attenuation curves for the same object differed according to the kind of screen resulting in a different image contrast. Contrast based on the screens with 37 to 50 keV K absorption edge were lower by a factor of about 10% compared to that of the calcium tungstate screen, in 60-1OO kV X-rays. These results showed no change in situation with and without scattered radiation. Image contrast due to screens is mainly caused by the differences in the K absorption energy of screen phosphors.
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NOBUO SATO
Article type: Article
1988 Volume 44 Issue 10 Pages
1505-1509
Published: October 01, 1988
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In place of a thermoluminescent dosimeter(TLD), a dosimetric system was developed to measure tissue-absorbed dose that provides a real-time reading with no correction required in a given energy range. Tests conducted by the authors proved that an anthracene detector is ideal to use at the mammographic energy range and that a calcium tungstate detector should be used in higher energy ranges. The use of a minute detector also makes it feasible to monitor intraluminal organs.
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KEISUKE KOBAYASHI, MASAAKI KAGAWA, HIROSHI YASUE, MASAAKI ASAI, KAZUHI ...
Article type: Article
1988 Volume 44 Issue 10 Pages
1510-1515
Published: October 01, 1988
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Several problems in acquring data from a hemodynamic analysis of the cervicocerebral region with the digital subtraction angiography (DSA) system was investigated. More accurate data were obtained in patients' movement setting the ROI background near the vessel of interest. The relationship between the concentration of the contrast medium and the DSA number were at a concentration of 1%, the acquired data of the DSA number were more dispersed with a concentration of more than 40%, they were closely resembled. It should be required that the hemodynamic analysis be performed within the limits of the existance of linearity between the concentration of the contrast medium and the DSA number. The suitable concentration, total medium volume and tube voltage were selected for higher sensitivity in the DSA number at a lower tube voltage and the size of the image intensifier of more less distortion should be selected during the hemodynamic study.
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TAKEO ORITO
Article type: Article
1988 Volume 44 Issue 10 Pages
1516-1519
Published: October 01, 1988
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YUKIMITSU SATOU
Article type: Article
1988 Volume 44 Issue 10 Pages
1520-1523
Published: October 01, 1988
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The applications of radiation to the medical field are increasing steadily, along with advances in radiation technology and development of new medical equipment. Medical applications of radiation differ from applications in other fields, because the patient is exposed to radiation during examination and radiotherapy. Consequently, it is important that training courses in radiation safety for radiological technologists, medical doctors and nurses be periodically carried out to ensure a more effective and safe utilization of radiation. Furthermore, it is important that such training be based on a practical education curriculum, including basic knowledge, technical training, and safe habits. In this paper, we discuss the appropriate role and attitudes of the radiological technologist in radiation safety education.
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TATAO ISE
Article type: Article
1988 Volume 44 Issue 10 Pages
1524-1527
Published: October 01, 1988
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Recent accelerating use of radiological diagnostic modalities is remarkably increasing in clinical medicine, but ionizing radiation safety and control system has not yet been established well enough for the hospitals in this country. My experience over the last 10 years in the management of radiation safety and control at my hospital has let me to point out the difficulties in controlling radiation, the kind uniquely existing in the hospital where patient' care and management are great matters of concern. A great deal of trouble lies in my earlier work concerning this matter. I would like to mention several changes carried out during the 5th and 12th year in order to improve the functions of the system. First, participating members of the organization has been increased by employing more radiological technologists who are qualified safety officers and active discussions on this matter have been encouraged and undertaken by them to make further improvements. Through these discussions, a manual has been completed in which is discribed management protocols for radiation safety and control. Each of these technologists is taking their turn to present some new ways to further improve on of radiation control.
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NORIYOSHI UMEZAKI, MASAHIDE KAWAMURA, TERUO MIYAGAWA, SEIJI KAWAMURA
Article type: Article
1988 Volume 44 Issue 10 Pages
1528-1534
Published: October 01, 1988
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A questionnaire was sent out for the purpose of trying to grasp the existing state of radiation measurement among the medical and dental school hospitals. It was pointed out that the accuracy of measurement regarding the X-ray examination is not better than therapeutics part concerning both standard and survey measurements. The reason for this is supposed due to the unsatisfactory dependence on the low energy using in the measuring instruments. The effect of energy on measurements and the dose equivalent at a 1 cm depth were discussed. 2) The back scatter radiation to the film badge is slightly effected by the X-ray energy. It is constant when the distance between the phantom and film badge is under 3 cm and reduced over 3 cm. By adopting ICRP Pub. 26 in the near future, the dose equivalent at a 1 cm depth should be mearsured in order to provide radiation protection. It is considered that the calbilation will be made using a phantom. If the caliblation is made at 3 cm distance between the phantom and film badge, the dose equivalent at 1 cm depth will be underestimated when the film badge is put at a distance of over 3 cm from the body. 3) The availability of silicon photodiode as a sensor was considered by the method in which an X-ray is directly exposured to one. The energy spectrum can be detected over the 15-200 keV range. It has been concluded that the usage of this sensor can calculate the dose equivalent at a 1 cm depth for lower energy radiation as using clinical examination.
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TOMOKO KUSAMA
Article type: Article
1988 Volume 44 Issue 10 Pages
1535-1539
Published: October 01, 1988
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The regulations of radiation protection for medicine are planning an amendment based on the ICRP recommendations in 1977 very soon in Japan. The main points of amendment are as follows : (1) SI quantities and units, that is Sv and Bq, are adopted ; (2) An effective dose equivalent is adopted and in lieu of the effective dose equivalent, I cm-dose-equivalent is used in the radiation protection practice ; (3) Annual effective dose-equivalent limit and each organ dose-equivalent limit for workers are setting at 50 mSv and 0.5 Sv, respectively ; (4) Radioactive concentration in effluent from institute are setting new values based on annual dose limits for public, that is 1 mSv/y and (5) Health surveillance for radiation workers are exempted in cases of annual dose equivalent under three tenth of the limits. Many people have indicated that the present situation of radiation protection in medicine is very poor. Therefore, improvements in the radiation protection practice in medicine, i.e., the setting of systems of administration and responsibility of protection and performance of education and training for workers, should be promoted. Radiological technicians should be practical leaders in promoting radiation protection in medicine from now on.
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IKURO ANZAI
Article type: Article
1988 Volume 44 Issue 10 Pages
1540-1544
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Article type: Article
1988 Volume 44 Issue 10 Pages
1545-1547
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1988 Volume 44 Issue 10 Pages
1548-1550
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
1551-1552
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
1552-1553
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
1553-1554
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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Article type: Appendix
1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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Article type: Appendix
1988 Volume 44 Issue 10 Pages
1558-1564
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Article type: Appendix
1988 Volume 44 Issue 10 Pages
1565-1567
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Article type: Appendix
1988 Volume 44 Issue 10 Pages
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1988 Volume 44 Issue 10 Pages
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