Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 67, Issue 10
Displaying 1-18 of 18 articles from this issue
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Opening Article
Originals
  • Optimization of the Scan Time is Based on the Physical Index in FDG-PET/CT
    Naoki Shimada, Hiromitsu Daisaki, Takeshi Murano, Takashi Terauchi, Hi ...
    2011 Volume 67 Issue 10 Pages 1259-1266
    Published: October 20, 2011
    Released on J-STAGE: October 26, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1259
    JOURNAL FREE ACCESS
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    Purpose: The image quality of Positron Emission Tomography (PET) using 18F-fluoro-2-deoxy-D-glucose is extremely important to diagnose cancer precisely. The purpose of this study is to inspect the physical indexes that are correlated with image quality and optimization of the scan time, utilizing the physical index. Methods: This study calculated two kinds of patient noise equivalent counts (NECpatient and NECdensity) and signal to noise ratio in liver (SNRliver) to measure PET image quality. We estimated the correlation coefficient between the visual assessment of PET image quality and physical indexes to assess the degree of correlation. We also set the optimal scan time, depending on body mass index (BMI), using the physical index and examined the efficacy of the optimization. Results: NECdensity showed the highest correlation coefficient in PET image quality (r=0.743, p<0.001). By optimizing the scan time using NECdensity, we showed there was no correlation between BMI and NECdensity (r=0.192, p=0.047). In addition, reduced dependence of the PET image quality by BMI was showed. Conclusion: The optimization of the scan time using NECdensity reduces deterioration of the PET image quality by patient habitus.
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  • Mechanical Accuracy of a Stereotactic Irradiation System Using a Micro Multi-leaf Collimator
    Daisaku Tatsumi, Ryosei Nakada, Shinichi Tsutsumi, Mariko Sakamoto, Ma ...
    2011 Volume 67 Issue 10 Pages 1267-1274
    Published: October 20, 2011
    Released on J-STAGE: October 26, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1267
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    Mechanical accuracy of a stereotactic irradiation system using a micro multi-leaf collimator (mMLC), Elekta DMLC, has been evaluated. Measurements were made to obtain transmission, leakage, penumbra, and positioning accuracy of the DMLC leaf for a 6 MV photon beam. Mechanical accuracy and long term stability of a linac isocenter was also evaluated. The resulting transmission, along a line perpendicular to the leaf movement, was 0.31±0.01%, and the leakage from the closed opposing leaf pairs was 0.39±0.01%. The measured penumbra, at a depth incurring maximum dose, was 2.37±0.16 mm toward the leaf end and 2.14±0.18 mm toward the leaf side for various field sizes. The leaf gap width error, of 0.10±0.08 mm, was obtained by analyzing picket fence test results. The maximum leaf positioning error, of 0.14±0.06 mm, was obtained by analyzing the log file for a various gantry angles during an arc delivery. The isocenter accuracy was within a radius of 1 mm, without any recalibration for two years. In conclusion, our stereotactic irradiation system using DMLC was capable of providing accurate stereotactic treatment.
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Notes
  • The Absorbed Dose and the Effective Dose of Panoramic Temporo Mandibular Joint Radiography
    Ayae Matsuo, Tsuneichi Okano, Kenichi Gotoh, Midori Yokoi, Akiko Hiruk ...
    2011 Volume 67 Issue 10 Pages 1275-1283
    Published: October 20, 2011
    Released on J-STAGE: October 26, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1275
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    Purpose: This study measured the radiation doses absorbed by the patient during Panoramic temporo mandibular joint radiography (Panoramic TMJ), Schüllers method and Orbitoramus projection. The dose of the frontal view in Panoramic TMJ was compared to that with Orbitoramus projection and the lateral view in Panoramic TMJ was compared to that with Schüllers method. Methods: We measured the doses received by various organs and calculated the effective doses using the guidelines of the International Commission on Radiological Protection in Publication 103. Organ absorbed doses were measured using an anthropomorphic phantom, loaded with thermoluminescent dosimeters (TLD), located at 160 sensitive sites. The dose shows the sum value of irradiation on both the right and left sides. In addition, we set a few different exposure field sizes. Result: The effective dose for a frontal view in Panoramic TMJ was 11 μSv, and that for the lateral view was 14 μSv. Conclusion: The lens of the Orbitoramus projection was 40 times higher than the frontal view in Panoramic TMJ. Although the effective dose of the lateral view in Panoramic TMJ was 3 times higher than that of the small exposure field (10×10 cm on film) in Schüller’s method, it was the same as that of a mid-sized exposure field. When the exposure field in the inferior 1/3 was reduced during panoramic TMJ, the effective doses could be decreased. Therefore we recommend that the size of the exposure field in Panoramic TMJ be decreased.
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  • Evaluation of Metal Artifact in Computed Radiography
    Kazushi Kitamura, Chieko Kida, Hidetaka Hayashi, Shigeo Nishiki
    2011 Volume 67 Issue 10 Pages 1284-1291
    Published: October 20, 2011
    Released on J-STAGE: October 26, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1284
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    We know that computed radiography (CR) has many factors to generate artifacts, such as the over / under shoot, aliasing and more. Recently, we encountered an artifact, we call a metal artifact, not attributable to any known factors in clinical images. To elucidate the cause of this artifact, we did some experiments with an in-house phantom. The experiments showed that the metal artifact was seen only when we put an object that absorbs X-rays parallel to the scanning line on imaging plate (IP). From these results, we speculated that the factor causing the afterglow is associated with photo-stimulated luminescence from IP.
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Clinical Technology
  • Evaluation of Crossing Calibration of 123I-MIBG H/M Ration, with the IDW Scatter Correction Method, on Different Gamma Camera Systems
    Daisuke Kittaka, Tadashi Takase, Masayuki Akiyama, Yasuo Nakazawa, Aki ...
    2011 Volume 67 Issue 10 Pages 1292-1297
    Published: October 20, 2011
    Released on J-STAGE: October 26, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1292
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    123I-MIBG Heart-to-Mediastinum activity ratio (H/M) is commonly used as an indicator of relative myocardial 123I-MIBG uptake. H/M ratios reflect myocardial sympathetic nerve function, therefore it is a useful parameter to assess regional myocardial sympathetic denervation in various cardiac diseases. However, H/M ratio values differ by site, gamma camera system, position and size of region of interest (ROI), and collimator. In addition to these factors, 529 keV scatter component may also affect 123I-MIBG H/M ratio. In this study, we examined whether the H/M ratio shows correlation between two different gamma camera systems and that sought for H/M ratio calculation formula. Moreover, we assessed the feasibility of 123I Dual Window (IDW) method, which is a scatter correction method, and compared H/M ratios with and without IDW method. H/M ratio displayed a good correlation between two gamma camera systems. Additionally, we were able to create a new H/M calculation formula. These results indicated that the IDW method is a useful scatter correction method for calculating 123I-MIBG H/M ratios.
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  • Basic Examination of an Imagecharacteristic in Multivane
    Tsuyoshi Ohshita
    2011 Volume 67 Issue 10 Pages 1298-1303
    Published: October 20, 2011
    Released on J-STAGE: October 26, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1298
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    Deterioration in the image because of a patient’s movement always becomes a problem in the MRI inspection. To solve this problem, the imaging procedure named Multivane was developed. The principle is similar to the periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) method. As for Multivane, the effect of the body motion correction is high. However, the filling method of k space is different than a past Cartesian method. A basic examination of the image characteristic of Multivane and Cartesian was utilized along with geostationary phantom. The examination items are SNR, CNR, and a spatial resolution. As a result, Multivane of SNR was high. Cartesian of the contrast and the spatial resolution was also high. It is important to recognize these features and to use Multivane.
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  • Evaluation of Left Ventricular Volumes and Ejection Fraction by Gated Myocardial Perfusion SPECT Versus Cardiac MRI
    Koutatsu Tsuboi, Hiraku Fuse, Masatoshi Sasaki
    2011 Volume 67 Issue 10 Pages 1304-1313
    Published: October 20, 2011
    Released on J-STAGE: October 26, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1304
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    It is stated that cardiac MRI imaging can provide accurate estimation of left ventricular (LV) volumes and ejection fraction (EF). The purpose of this study was to evaluate the accuracy of gated myocardial perfusion SPECT for assessment of LV end-diastolic volume (EDV), end-systolic volume (ESV) and EF, using cardiac MRI as the reference methods/(methodology). Gated myocardial perfusion SPECT images were analyzed with two different quantification software, QGS and 4D-MSPECT. Thirty-four consecutive patients were studied. Myocardial perfusion SPECT and cardiac MRI had excellent intra/interobserver reproducibility. Correlation between the results of gated myocardial perfusion SPECT and cardiac MRI were high for EDV and EF. However, ESV and EDV were significantly underestimated by gated myocardial perfusion SPECT compared to cardiac MRI. Moreover, gated myocardial perfusion SPECT overestimated EF for small heart. One reason for the difference in volumes and EF is the delineation of the endocardial border. Cardiac MRI has higher spatial resolution. We should understand the differences of volumes and EF as determined by gated myocardial perfusion SPECT and cardiac MRI.
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Data
  • Collection of Information Regarding Implants, Internal and External Metallic Objects for MRI Examinations
    Masaki Kobayashi, Masato Kobayashi, Tatsuya Someno, Hiromi Uchiyama, Y ...
    2011 Volume 67 Issue 10 Pages 1314-1319
    Published: October 20, 2011
    Released on J-STAGE: October 26, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1314
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    In Japan, various types of MRI equipment, having varying magnetic field strengths, are widely used. However, the biggest problem encountered while utilizing an MRI is the scarcity of information and guidelines pertaining to implants, internal, and external metallic objects. This leads to uncertainty when an unspecified object is encountered during an examination andcreates the possibility of performing an ambiguous MRI. Therefore, this study classified a range of objects into 12 categories using database management software. An attempt was made to create an environment where reference and comparison of products could be performed. This study also investigated the ways and extent to which medical equipment package inserts reference the MRI. With the co-operation of various corporations and the use of information such as medical equipment package inserts, product information was collected and an environment for the reference and comparison of products became available. In addition, it became apparent while examining these package inserts that orthopedic products had the least information available. It is likely that this information will be useful in medical settings and this kind of database will become increasingly necessary in the future.
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  • Problems of the Effective Energy Used as a Quality Expression of Diagnostic X-ray
    Hideki Kato, Naoki Hayashi, Shoichi Suzuki, Sho Ando, Mami Miyamoto, N ...
    2011 Volume 67 Issue 10 Pages 1320-1326
    Published: October 20, 2011
    Released on J-STAGE: October 26, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1320
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    The effective energy has been generally used as a method of handily expressing an X-ray quality by one numerical value. The effective energy is a concept derived from “Half Value Layer (HVL)” that is the expressing parameter of beam quality based on the attenuation of the primary X-ray by a material. When beam quality is expressed by using HVL and / or the effective energy, it is necessary to describe the tube potential, the rectification method, and the homogeneity coefficient, etc. in parallel. However, recently feelings are that the effective energy should be handled like an absolute numerical value to physical characteristics of X-rays. In this paper, it was theoretically clarified that the effective energy had a different value depending on the absorber material used for the HVL measurement. In addition, the errors when physical characteristics of the X-rays were evaluated using the effective energy was also examined. Physical characteristics, such as interactions to the material of mono-energetic X-ray, are not equal to that of X-rays with a wide energy spectrum. It is not an easy comparison to express the quality of the diagnostic X-rays, and to calculate physical characteristics of the X-rays by using the effective energy. It is necessary to design a new method of expressing the quality of X-rays that takes the place of the “effective energy.”
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Special Plan–Member Interview–
Educational Lecture–Radiation Measurement in the Clinical Setting
Basic Lecture–Radiation Therapy Technology: Basic Strategy
Virtual Interview for Graduate School and Laboratories
Committee Reports
JIRA Topics
About JSRT (Japanese Society of Radiological Technology)
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