Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 67, Issue 8
Displaying 1-14 of 14 articles from this issue
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Opening Article
Originals
  • Evaluation of Low-contrast Detectability in Low-dose Chest Computed Tomography
    Yohei Miura, Katsuhiro Ichikawa, Takanori Hara, Shinji Niwa, Ichiro Fu ...
    2011 Volume 67 Issue 8 Pages 873-879
    Published: August 22, 2011
    Released on J-STAGE: August 24, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.873
    JOURNAL FREE ACCESS
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    We investigated whether low-contrast resolution evaluation can be applied to chest (lung field) computed tomography (CT) images that are commonly reconstructed using filter kernels with strong frequency emphasis and displayed at wide window widths. We assumed low dose chest CT examinations and set the current-time product to 5 and 10 mAs. The visual detection study was performed by five radiological technologists using water phantom images in which the simulated low contrast objects (disc objects) were implanted. In addition, values of the low contrast detectability index (LCDI) based on a signal-to-noise ratio theorem were calculated from the modulation transfer factor, noise power spectrum, and the object’s spectrum for each combination of object size, contrast, current-time product, and kernel. The detectability results correlated well with the LCDI values and correlated less well with the contrast-to-noise ratio results. These results were consistent with the results of past reports on abdomen images. Therefore, our results indicated that low contrast sensitivity can be applied to chest CT images as well as abdominal ones.
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  • A Comparative Study of Electrocardiogram Multi-segment Reconstruction and Dual Source Computed Tomography Using a Computer Controlled Coronary Phantom
    Kazuya Ohashi, Katsuhiro Ichikawa, Ryo Higashide, Hirosi Kunitomo
    2011 Volume 67 Issue 8 Pages 880-887
    Published: August 22, 2011
    Released on J-STAGE: August 24, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.880
    JOURNAL FREE ACCESS
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    Currently, there are two main methods for improving temporal resolution of coronary computed tomography (CT): electrocardiogram-gated multi-segment reconstruction (EMR) and dual source scanning using dual source CT (DSCT). We developed a motion phantom system for image quality assessment of cardiac CT to evaluate these two methods. This phantom system was designed to move an object at arbitrary speeds during a desired phase range in cyclic motion. By using this system, we obtained coronary CT mode images for motion objects like coronary arteries. We investigated the difference in motion artifacts between EMR and the DSCT using a 3-mm-diameter acrylic rod resembling the coronary artery. EMR was evaluated using 16-row multi-slice CT (16MSCT). To evaluate the image quality, we examined the degree of motion artifacts by analyzing the profiles around the rod and the displacement of a peak pixel in the rod image. In the 16MSCT, remarkable increases of artifacts and displacement were caused by the EMR. In contrast, the DSCT presented excellent images with fewer artifacts. The results showed the validity of DSCT to improve true temporal resolution.
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Notes
  • Improved Visualization of Long-axis Black-blood Imaging of the Carotid Arteries Using Phase Sensitive Inversion Recovery Combined with 3D IR-T1TFE
    Tomohiko Horie, Mami Kawakata, Nao Kajihara, Hayato Takano, Masatoshi ...
    2011 Volume 67 Issue 8 Pages 888-894
    Published: August 22, 2011
    Released on J-STAGE: August 24, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.888
    JOURNAL FREE ACCESS
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    The purpose of this study was to improve the visualization of long-axis black-blood imaging of the carotid arteries. We experimented on phantom and in-vivo study of 3 dimension (3D) inversion recovery T1 turbo field echo combined with phase sensitive inversion recovery (PSIR-3D IR-T1TFE) at 3.0 Tesla. As a result, the contrast has been improved by calculated images of PSIR-3D IR-T1TFE set to inversion time (TI) 350 ms that is shorter than null point of blood. This displays that the contrast between blood and tissues can be improved when the longitudinal magnetization of blood is a negative. Therefore, the visualization of long-axis black-blood imaging of the carotid arteries has been improved by the calculated images of PSIR-3D IR-T1TFE set to TI that is shorter than null point of blood.
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  • An Investigative Report Concerning Safety and Management in the Magnetic Resonance Environment: There Are More Accidents than Expected
    Tsukasa Doi, Yuya Yamatani, Tsuyoshi Ueyama, Shigeo Nishiki, Akio Ogur ...
    2011 Volume 67 Issue 8 Pages 895-904
    Published: August 22, 2011
    Released on J-STAGE: August 24, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.895
    JOURNAL FREE ACCESS
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    Using a questionnaire, we surveyed 2,500 facilities in Japan to clarify medical accidents concerning the magnetic resonance device and its environment. Data derived from 1,319 valid responses (52.8%), allowed us to analyze the situation of (or the reason for) the occurrence of the accidents and their environmental factors. Five hundred and nine facilities (39% of all facilities) had the experience of magnetically induced displacement of the large ferromagnetic material. Intravenous (I.V.) drip stands were involved the largest number of them: 31% (228 cases). Oxygen bottles had the second largest number of incidents: 20%. There were also many incidents involving various materials brought in by non-medical staff (e.g. stepladder for construction). About 20% of the accidents occurred outside of working hours. Patients in 12% of the facilities (154 facilities) experienced burns. In 39 of the cases, burns were received to the inside of the thighs. In 38 of the cases, patients received burns from an electrical cable touching the skin. There were also frequent incidents of burning regarding the boa. We received reports of burns and pain from the halo vest even though it’s required to be worn for MR safety. Regarding incidents of contraindications, 280 patients with pacemakers were brought into the magnetic resonance (MR) inspection room. Twelve percent of the facilities experienced natural quench. Lack of training for the staff who introduce and operate high magnetic field devices are considered involving frequently occurring accidents of attractions and burns at hospitals with over 500 beds caused by carrying in materials.
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Clinical Technology
  • Image Quality Assessment of Step&Shoot Overlap Reconstruction (SSOR) for Cardiac Computed Tomography (CT)
    Taiki Chono, Tohru Hirano, Takeshi Inoue, Shinichi Tokuyasu, Ko Higuch ...
    2011 Volume 67 Issue 8 Pages 905-911
    Published: August 22, 2011
    Released on J-STAGE: August 24, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.905
    JOURNAL FREE ACCESS
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    Background: Step&Shoot cardiac computed tomography (CT) provides the benefit of significant reduction in radiation dose compared to helical cardiac CT acquisitions. We think that a difference occurs in image quality by presence of overlap reconstruction (fractionated sentence, attempted to clarify). Purpose: We studied the utility of Step&Shoot overlap reconstruction (SSOR). Methods: We evaluated image quality of SSOR by comparing z-axis spatial resolution on various s in scanners that SSOR is possible and for those that are impossible. Results: SSOR indicated better z-axis spatial resolution and less variation over the field of view (FOV) (in z & x-y directions) as compared with Step&Shoot without overlap reconstruction (SS). In addition, SS showed inadequate image reproducibility due to aliasing error in z-direction (lack of sampling interval). Conclusions: SSOR would contribute to improvement of the image quality of Step&Shoot cardiac CT.
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Work in Progress
  • Effective Method for Decontaminating Radioactive X-ray Detectors (Imaging Plates)
    Sadamitsu Nishihara, Hiroaki Hayashi
    2011 Volume 67 Issue 8 Pages 912-915
    Published: August 22, 2011
    Released on J-STAGE: August 24, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.912
    JOURNAL FREE ACCESS
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    Several hospitals have been observing black spots in medical images, and the radioisotopes (RIs) that cause the spots needs to be removed from the X-ray receptors. Our purpose is to show a flowchart for finding out under which conditions an imaging plate (IP) and other parts (for example, the cassette) are contaminated by RIs and to propose an effective method to remove them. The procedure follows. (1) Is RI activity low? (2) Are the surfaces of other parts contaminated? (3) Is the surface of the IP contaminated? (4) Are the insides of the other parts contaminated? To remove the adhered RIs, we applied a wipe test method using a wet type of chemical wiper. A certain hospital that observed black spots experimented with this method. As a result, the contaminated condition of the X-ray receptor was identified. In addition, we were able to remove the RIs from the IP. Therefore, our procedure is very effective for decontaminating adhered RIs from receptors.
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The 66th Annual Scientific Congress
Educational Lecture—Radiation Measurement in the Clinical Setting
Basic Lecture—Radiation Therapy Technology: Basic Strategy
Virtual Interview for Graduate School and Laboratories
Science Exchanges Committee News
JIRA Topics
About JSRT (Japanese Society of Radiological Technology)
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