Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 65, Issue 12
Displaying 1-14 of 14 articles from this issue
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Opening Article
Originals
  • Influence on the Physical Characteristics of Medical Color Liquid Crystal Displays with Increase in Aperture Ratio
    Michito Sawada, Akinori Ishikawa, Sayoko Matsunaga, Yoko Ishikawa
    2009 Volume 65 Issue 12 Pages 1611-1617
    Published: November 25, 2009
    Released on J-STAGE: February 03, 2010
    DOIhttps://doi.org/10.6009/jjrt.65.1611
    JOURNAL FREE ACCESS
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    We measured the physical characteristics of 2-million(2M)and 3-million(3M)color liquid crystal displays(LCD)whose aperture ratio was increased and compared them with conventional models. The results showed the influence of the increased aperture ratio on the physical characteristics of the LCDs. We evaluated resolution by means of modulation transfer function(MTF)and evaluated granularity by means of noise power spectrum(NPS). Each of the measurements was done with a high-resolution single-lens reflex-type digital camera. A decrease of MTF depending on sub-pixel structures was recognized. A decrease in the cross sub-pixel direction was recognized in the 2M model, and a decrease in the sub-pixel direction was recognized in the 3M model. As for NPS, a reduction was recognized in the sub-pixel and the cross sub-pixel direction in both models. As a result, an improvement in granularity was recognized. The improvement in granularity was large with the color LCDs whose aperture ratio was increased. The increase of an aperture ratio influenced both MTF and NPS, and the results depended on the shape and size of the sub-pixel cells.
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  • Evaluation of Irreversible Compressed Images in Computed Radiography Using Physical Image Quality Measures
    Haruyuki Watanabe, Du-Yih Tsai, Yongbum Lee, Tomohiro Nakamura, Masano ...
    2009 Volume 65 Issue 12 Pages 1618-1627
    Published: November 25, 2009
    Released on J-STAGE: February 03, 2010
    DOIhttps://doi.org/10.6009/jjrt.65.1618
    JOURNAL FREE ACCESS
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    Joint photographic experts group(JPEG)and JPEG2000 are widely used as image compression algorithms in medical image database systems. Compressed images have been mainly evaluated by visual assessment on acceptable compression levels in clinical studies. However, to the best of our knowledge, little work has been done to clarify image properties based on physical analysis. In this work, investigations were made to clarify image properties based on physical analysis and to discuss the major causes of degradation related to compression ratios. The physical properties of JPEG2000-compressed and JPEG-compressed images in computed radiography(CR)were compared by measuring the characteristic curve, modulation transfer function(MTF), noise power spectrum(NPS), peak signal-to-noise ratio(PSNR), contrast-to-noise ratio(CNR), and noise equivalent quanta(NEQ). In the MTF measurement, the MTFs of JPEG at high compression ratio showed pronounced degradation at all frequencies. The NPS values of JPEG2000 tend to decrease considerably compared to that of the JPEG at all frequencies with the increase of compression ratio. Furthermore, JPEG2000 images showed higher PSNR, CNR, and NEQ values than JPEG images in the same compression ratio. In these signal-to-noise ratio measurements, good reproducibility of JPEG2000 images was achieved. Overall, JPEG2000 compressed images were far superior to JPEG compressed images. In the physical properties measured, these physical analyses are useful to comprehend physical properties for each irreversible compressed image related to compression ratios in CR.
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  • Breast Dose Reduction in Female CT Screening for Lung Cancer Using Various Metallic Shields
    Kenta Takada, Junichi Kaneko, Kiyoshi Aoki
    2009 Volume 65 Issue 12 Pages 1628-1637
    Published: November 25, 2009
    Released on J-STAGE: February 03, 2010
    DOIhttps://doi.org/10.6009/jjrt.65.1628
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    We evaluated the effectiveness of metallic shields that were used for reduction of the breast dose in thoracic computed tomography(CT). For the evaluation, we measured breast surface dose and image standard deviation(SD)in the lung area. The metallic shields were made from bismuth, zinc, copper, and iron. The bismuth shield has been marketed and used for dose reduction. The other three metallic shields were chosen because they have lower atomic numbers and a lower yield of characteristic X-rays. As a result, use of the metallic shields showed a lower breast dose than the decrement of the tube current in the same image SD. The insertion of a thin aluminum sheet between the shield and a phantom was also effective in reducing breast surface dose. We calculated the dose reduction rate to evaluate the effectiveness of these metallic shields. This dose reduction rate was defined as the ratio of the decrease in breast surface dose by metallic shields to the breast surface dose measured with the tube current decrement in the same image SD. The maximum dose reduction rate was 6.4% for the bismuth shield, and 12.0–13.3% for the other shields. These results indicate that the shields made from zinc, copper, and iron are more effective for dose reduction than the shield made form bismuth. The best dose reduction rate, 13.3%, has been achieved when the zinc shield placed 20 mm apart from a phantom with 0.2 mm aluminum was used.
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Clinical Technology
  • Cooperation with the Electronic Medical Record and Accounting System of an Actual Dose of Drug Given by a Radiology Information System
    Hideo Yamamoto, Tarou Yoneda, Shuji Satou, Toru Ishikawa,, Misako Hara
    2009 Volume 65 Issue 12 Pages 1638-1643
    Published: November 25, 2009
    Released on J-STAGE: February 03, 2010
    DOIhttps://doi.org/10.6009/jjrt.65.1638
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    By input of the actual dose of a drug given into a radiology information system, the system converting with an accounting system into a cost of the drug from the actual dose in the electronic medical record was built. In the drug master, the first unit was set as the cost of the drug, and we set the second unit as the actual dose. The second unit in the radiology information system was received by the accounting system through electronic medical record. In the accounting system, the actual dose was changed into the cost of the drug using the dose of conversion to the first unit. The actual dose was recorded on a radiology information system and electronic medical record. The actual dose was indicated on the accounting system, and the cost for the drug was calculated. About the actual dose of drug, cooperation of the information in a radiology information system and electronic medical record were completed. It was possible to decide the volume of drug from the correct dose of drug at the previous inspection. If it is necessary for the patient to have another treatment of medicine, it is important to know the actual dose of drug given. Moreover, authenticity of electronic medical record based on a statute has also improved.
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Data
  • Nationwide Survey on Radioactive Waste Management Related to Positron Emission Tomography in Japan
    Hiroaki Nagaoka, Hiroshi Watanabe, Ichiro Yamaguchi, Toshioh Fujibuchi ...
    2009 Volume 65 Issue 12 Pages 1644-1649
    Published: November 25, 2009
    Released on J-STAGE: February 03, 2010
    DOIhttps://doi.org/10.6009/jjrt.65.1644
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    Background and Purpose: A clearance system for medical radioactive solid waste has not yet been implemented in Japan. Since 2004 new regulations have allowed institutions using positron emission tomography(PET)to handle totally decayed radioactive waste as non-radioactive waste after decay-in-storage. It was expected that this new regulation would mediate the installation of clearance systems in Japan. In order to assess the current situation of radiation safety management in PET institutions, we conducted a nationwide survey. Methods: The study design was a cross-sectional descriptive study conducted by questionnaire. The subjects of this survey were all the PET institutions in Japan. Among 224 institutes, 128 institutes are equipped with cyclotrons and 96 institutes are not. The number of returned questionnaires was 138. Result: Among institutes that are using delivered radiopharmaceuticals, 80% treat their waste as non-radioactive according to the new regulation. The impact of new regulations for reducing radioactive waste in PET institutes without a cyclotron was estimated at about $400 thousand per year. Discussion: The main concern of medical institutes was assessment of the contamination caused by by-products of radioactive nuclides generated in target water during the operation of a cyclotron. It was thought that a rational rule based on scientific risk management should be established because these by-products of radioactive nuclides are negligible for radiation safety. Conclusion: New regulation has had a good influence on medical PET institutes, and it is expected that a clearance system for medical radioactive waste will be introduced in the near future, following these recent experiences in PET institutes.
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  • Effectiveness of a Positioning Doll for Radiography: through Performance as a Practice of Radiography Training and a Questionnaire Targeted for Radiological Technologists
    Kosuke Matsubara, Masayuki Suzuki, Etsuro Taka, Kichiro Koshida, Akihi ...
    2009 Volume 65 Issue 12 Pages 1650-1657
    Published: November 25, 2009
    Released on J-STAGE: February 03, 2010
    DOIhttps://doi.org/10.6009/jjrt.65.1650
    JOURNAL FREE ACCESS
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    The effectiveness of a positioning doll for radiography training(XPD)and acquiring the techniques of radiography was evaluated through performing radiography practice for the students in our school of radiological technologists and a questionnaire for radiological technologists. We made a ranking test composed of a five-grade evaluation system of the 39 students for the techniques of radiography before and after the practice, and questionnaires about the XPD were given to the same students after the practice. The questionnaires about affinities between human bodies and the XPD and effectiveness of the XPD for the education of students were also carried out in six radiological technologists to examine the effectiveness of the practice of radiography by using the XPD. The rankings of the students after the practice were significantly higher than those before the practice(p <0.01), and 85% of the students rated the practice using the XPD as useful for them in acquiring the techniques of radiography. Seventy-eight percent of the radiological technologists rated it useful for student education in radiography. In conclusion, it was suggested that practice using the XPD was effective in helping students to acquire the techniques of radiography. We would like to develop supplementary tools for fixing the XPD and using the practice of radiography in many ways and in new directions in the future.
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The 36th Autumn Scientific Congress
Educational Lecture-Basic Thinking of Image Analysis
Basic Lecture-Physical Image Quality Assessment in Digital Radiography
Basic Lecture-How to Make Use of Softwares
Clinical Technology Course
Science Exchanges Committee News
JIRA Topics
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