Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 64, Issue 3
Displaying 1-16 of 16 articles from this issue
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Opening Article
Originals
  • Total Breathing Phase Scan (slow scan) Method in the Free Breathing State by Multi-detector-row Computed Tomography Scanner in Radiotherapy Planning
    Masayuki Tachibana
    2008 Volume 64 Issue 3 Pages 297-305
    Published: March 20, 2008
    Released on J-STAGE: April 24, 2008
    DOIhttps://doi.org/10.6009/jjrt.64.297
    JOURNAL FREE ACCESS
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    With the new high-speed computed tomography (CT) devices, the longest scan time for a conventional scan is about 2 seconds. Therefore, the all-breathing-phase scan (slow scan) in the free-breathing state, which includes an entire breathing phase of three or four seconds in one imaging section, is impossible. We performed spiral scanning with a low-speed scanning pitch using multi detector-row CT (4MDCT) and examined a method of scanning that was similar to the slow scan method. As a result, with the scanning diagram, we demanded the image data time than a combination of scanning pitch and X-ray tube rotation time, image data time of 6.66 seconds longest in scanning slice thickness 1 mm×4 detectors and reconstruction slice thickness 2 mm was possible, and the scanning that was similar to the slow scan method was possible. Furthermore, it was good in the image data time when we demanded it from scanning diagram and, as a result of confirmation of image data time by the equal speed turn phantom, agreed. In addition, there is not increase of a radiation exposure dose by this method, and this method is a useful method. (Article in Japanese)
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  • Estimation of Collimator Scatter Factor, Sc, of Small Field Sizes Using Long-SCD Method and Two Saturation Models
    Hiromi Adachi, Hideki Inakoshi, Takahide Hayakawa, Tomio Inoue, Toshif ...
    2008 Volume 64 Issue 3 Pages 306-315
    Published: March 20, 2008
    Released on J-STAGE: April 24, 2008
    DOIhttps://doi.org/10.6009/jjrt.64.306
    JOURNAL FREE ACCESS
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    To estimate the collimator scatter factor, Sc of small field sizes in which a mini-phantom cannot be fully included at the nominal treatment distance (NTD=100 cm), we measured the in-air output of 4 MV and 10 MV X-rays of a Varian’s Clinac 2100 C/D using a mini-phantom at NTD and at a long source-to-chamber distance (SCD=200 cm) with field-size defined at the isocenter down to 4.6×4.6cm2 and 2.3×2.3cm2, respectively. We then compared the fitted curve to the NTD dataset by a cumulative exponential distribution model with that by a cumulative Gaussian distribution (error function) model containing a zero-field extrapolated term derived from the long SCD dataset. The results showed that the zero-field extensions of two fitted curves coincided for a 4 MV X-ray, but a large discrepancy was seen between them for a 10 MV X-ray. Therefore, the Sc of small field sizes not measurable using a mini-phantom at the NTD can be well estimated by applying the cumulative exponential model to the NTD dataset in the case of a 4 MV X-ray beam filtrated with a cone-shaped flattener. However, to estimate the Sc of such small field sizes in the case of a 10 MV X-ray beam filtrated with a bell-shaped flattener, we consider it preferable to also measure in-air output at a long SCD and to apply the cumulative Gaussian model as described here. (Article in Japanese)
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  • Improvement of Overall Performance for Lung Nodule Detection in Chest CT Images
    Megumi Yamamoto, Ikuo Kawashita, Yasuhiko Okura, Mitoshi Akiyama, Koic ...
    2008 Volume 64 Issue 3 Pages 316-324
    Published: March 20, 2008
    Released on J-STAGE: April 24, 2008
    DOIhttps://doi.org/10.6009/jjrt.64.316
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    We have developed an automated computerized schema for the detection of lung nodules in 3D CT images obtained by helical CT. In our previous schema, linear discriminant analysis (LDA) and a rule-based method with 53 image features were employed in order to reduce false positives. However, several false positives have remained. Therefore, in this study, we improved the false-positive reduction technique by using the edge image and radial image analysis. Overall performance for the detection of lung nodules was greatly improved. Sensitivity was higher than that of our previous study. Moreover, we evaluated the overall performance of the new scheme by using 69 cases acquired from four hospitals. The average number of false positives was 5.2 per case at a percent sensitivity of 95.8%. Our new scheme would assist in the detection of early lung cancer. (Article in Japanese)
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Clinical Technology
  • A Method of Reconstructing Coronary Stent and Lumen Image Using Zero Cross Point Image for the Purpose of Improving Sharpness
    Kouki Shibuya, Masao Fujihara, Yuji Mizuguchi
    2008 Volume 64 Issue 3 Pages 325-334
    Published: March 20, 2008
    Released on J-STAGE: April 24, 2008
    DOIhttps://doi.org/10.6009/jjrt.64.325
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    Our purpose was to improve the sharpness of the coronary stent and lumen. We reconstructed volume rendering (VR) image and maximum intensity projection (MIP) images using the original image and a sharpened operator image with 8-neighbor Laplacian filter. The most suitable center number was 9, and the circumferential number was −1 on the sharpened operator image with 8-neighbor Laplacian filter. In the same way, the most suitable spatial filter was the FC43. VR and MIP images showed sharp stents. The VR image and MIP image fused the original image and sharpened the operator image with the 8-neighbor Laplacian filter, resulting in a clear lumen. The 8-neighbor sharpened operator image with 8-neighbor Laplacian filter was attached to the Aquilion64, and this method did not require extra hardware and software for reconstructing images of the stent and lumen. (Article in Japanese)
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Data
  • Experimental Study of the Influence on Pacemakers of X-rays from Angiocardiography Equipment
    Osamu Nakamura, Giichirou Nakaya, Susumu Ogashiwa, Akio Hashimoto, Mas ...
    2008 Volume 64 Issue 3 Pages 335-341
    Published: March 20, 2008
    Released on J-STAGE: April 24, 2008
    DOIhttps://doi.org/10.6009/jjrt.64.335
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    We performed an experimental study of the influence on pacemakers (PM) of X-rays from the angiocardiography equipment. (1) We used one PM of DDD mode in this study. (2) The PM was irradiated under two exposure levels: one the standard dose and the other the maximum dose in the angiocardiography study situation. (3) We set the pacing lead wires to the bilateral atria and ventricles in Irnich’s human body model. (4) We set two irradiation fields, one with a lead block on the PM and the other without the lead block. The result showed that when the PM was included in the irradiation field and the exposure level was of the maximum dose, the influence of irradiation on the PM was that of level 2 as classified by a research report by the Ministry of Internal Affairs and Communications. The absorbed dose of the PM was 93.4 mGy under these conditions. We confirmed that radiation dose does not affect a pacemaker with pacing lead wire. However, it acts on the generator of the PM owing to the direct photoelectric effect. When there were many dose rates (or total radiation dose), an obstacle occurred. (Article in Japanese)
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The 63rd Annual Scientific Congress
Educational Lecture—Interpreting Medical Images for Radiological Technologists
Basic Lectures—The Image Processing Technology that You Should Learn on Examination
Clinical Technology Cource
Series—Law and Medicine (8)
Scientific Committee Report
Science Exchanges Committee Report
JIRA Topics
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