Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 70, Issue 7
Displaying 1-13 of 13 articles from this issue
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Opening Article
Notes
  • Scan Parameters and the Diffusion Emphasis Effect in Diffusion-weighted Imaging Using a Motion-probing Gradient Preparation Pulse
    Daisuke Takahashi, Hajime Tanji, Tomoya Yamaki, Makoto Obara, Yoshio M ...
    2014 Volume 70 Issue 7 Pages 637-645
    Published: 2014
    Released on J-STAGE: July 23, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.7.637
    JOURNAL FREE ACCESS
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    Diffusion-sensitized driven equilibrium preparation (DSDE) is a gradient echo (GRE) diffusion-weighted imaging (DWI) sequence that employs a motion-probing gradient (MPG) preparation pulse and phase cycling. In DSDE, several scan parameters of the MPG preparation pulse and the GRE sequence affect diffusion sensitivity. Our investigation of the relationship between these scan parameters and the diffusion emphasis effect revealed the importance of “prep.TE” in the MPG preparation pulse and “TFE shot interval” in the gradient echo sequence. Appropriate choice of these parameters allows DSDE to provide a similar DWI to that of conventional single-shot SEEPI DWI. We therefore concluded DSDE to be a useful DWI method.
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  • Radiation Dose Evaluation in 3D Rotation Angiography and Cone-beam Computed Tomography with a Flat Panel Detector
    Shigenobu Seguchi, Takaya Saijou, Yoshinobu Ishikawa, Shuji Koyama
    2014 Volume 70 Issue 7 Pages 646-652
    Published: 2014
    Released on J-STAGE: July 23, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.7.646
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    The aim of this study was to evaluate radiation dose in patients undergoing three-dimensional rotation angiography (3DRA) and cone-beam computed tomography (CBCT) using a flat panel detector (FPD). Radiation doses were measured for angiography equipment using small silicon-photodiode dosimeters that were implanted in various positions in tissues and organs within an anthropomorphic phantom of a standard Japanese adult male. Output signals from the dosimeters were read out on a computer, from which organ and effective doses were calculated according to guidelines published in International Commission on Radiological Protection Publication 103. Lens doses and effective doses obtained in this study were 1.6 mGy and 0.13 mSv for 3DRA, 20 mGy and 1.7 mSv for CBCT (normal mode). 3DRA provided substantial lens doses and effective dose reduction, which were 8% of the doses in CBCT (normal mode).
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  • Investigation of Measurement Accuracy of Factors Used for Detective Quantum Efficiency Measurement in Digital Radiography
    Hiroshi Kunitomo, Shuji Koyama, Ryo Higashide, Katsuhiro Ichikawa, Mas ...
    2014 Volume 70 Issue 7 Pages 653-661
    Published: 2014
    Released on J-STAGE: July 23, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.7.653
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    In the detective quantum efficiency (DQE) evaluation of detectors for digital radiography (DR) systems, physical image quality indices such as modulation transfer function (MTF) and normalized noise power spectrum (NNPS) need to be accurately measured to obtain highly accurate DQE evaluations. However, there is a risk of errors in these measurements. In this study, we focused on error factors that should be considered in measurements using clinical DR systems. We compared the incident photon numbers indicated in IEC 62220-1 with those estimated using a Monte Carlo simulation based on X-ray energy spectra measured employing four DR systems. For NNPS, influences of X-ray intensity non-uniformity, tube voltage and aluminum purity were investigated. The effects of geometric magnifications on MTF accuracy were also examined using a tungsten edge plate at distances of 50, 100 and 150 mm from the detector surface at a source-image receptor distance of 2000 mm. The photon numbers in IEC 62220-1 coincided with our estimates of values, with error rates below 2.5%. Tube voltage errors of approximately ±5 kV caused NNPS errors of within 1.0%. The X-ray intensity non-uniformity caused NNPS errors of up to 2.0% at the anode side. Aluminum purity did not affect the measurement accuracy. The maximum MTF reductions caused by geometric magnifications were 3.67% for 1.0-mm X-ray focus and 1.83% for 0.6-mm X-ray focus.
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Clinical Technologies
  • Optimization of Reconstruction Parameters Using a Multi-focus Fan Beam Collimator in Myocardial Perfusion Single Photon Emission Computed Tomography Study
    Shuji Kenda, Hideo Onishi, Kenta Nakamoto
    2014 Volume 70 Issue 7 Pages 662-669
    Published: 2014
    Released on J-STAGE: July 23, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.7.662
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    Purpose: The aim of this study was to optimize the reconstruction parameters for ordered subset conjugate gradient minimization (OSCGM) reconstruction using a multifocus fan beam collimator in myocardial perfusion single photon emission computed tomography (SPECT). Method: We attempted to validate the following performance of OSCGM reconstruction parameters (iteration and subset). SPECT images were acquired using a dual-head gamma camera with IQ mode acquisition systems from a RH-2 cardiac phantom containing a 99m-Tc solution. The performance was evaluated using reconstruction parameters (product of subset and iteration: SI) with image contrast, LV volume [using quantitative perfusion SPECT (QPS)], root mean square uncertainty (RMSU), and normalized mean squared error (NMSE). Results: The best results (contrast, uniformity, LV volume, and NMSE) were found for SI: 30. LV volume indicated the true volume for subset: 1 and iteration: 30, and LV volume was underestimated by 10% for iteration >20, and subset >1. Conclusion: The results of this myocardial perfusion SPECT study suggest the optimal OSCGM reconstruction parameter to be subset: 1 and iteration: 30 using a multifocus fan beam collimator.
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  • Visualization of the Foramen Intervertebral Nerve Root of Cervical Spine with 3.0 Tesla Magnetic Resonance Imaging: A Comparison of Three-dimensional Acquisition Techniques
    Hiroki Shishido, Hiroyuki Takashima, Tsuneo Takebayashi, Yoshihiro Aka ...
    2014 Volume 70 Issue 7 Pages 670-675
    Published: 2014
    Released on J-STAGE: July 23, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.7.670
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    Identification of the compression factor in cervical disc herniation and cervical spondylotic radioculopathy is often problematic when using two-dimensional magnetic resonance imaging (MRI). This prompted us to compare and examined three-dimensional sequences, coherent oscillatory state acquisition for the manipulation of image contrast (COSMIC), fast imaging employing steady state acquisition (FIESTA) and T2 star weighted MR angiography (SWAN) with 3.0-Tesla (T) MRI to visualize the foramen intervertebral nerve root for the cervical spine. Fat-suppressed COSMIC (FS-COSMIC) sequence gave the highest signal intensity ratio (1.85±0.06) of the nerve root and vertebral arch. A significant difference in signal intensity ratio of the nerve root was found between FS-COSMIC and FIESTA sequences. No significant difference was found between the FS-COSMIC and FIESTA sequences in the cerebrospinal fluid and the spinal cord. The FS-COSMIC sequence proved to be the most suitable sequence for intra and extra dura matter.
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  • Experience of Low Volume Split-dose Bowel Preparation for Computed Tomography Colonography
    Teruaki Iwano, Masahide Tominaga, Hideyo Yamashita, Takashi Egawa, Jun ...
    2014 Volume 70 Issue 7 Pages 676-683
    Published: 2014
    Released on J-STAGE: July 23, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.7.676
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    We propose a new preparation method for the computed tomography colonography (CTC). This method consists of giving a small volume (400 ml) of cleansing solution on the day before the examination and the same volume of solution on the day of the examination [low volume split-dose (LVSD) method]. Using this method, we compared the volume of residual fluid in the colon, the CT value of the residual fluid, and the quality of stool tagging with those for patients undergoing the conventional bowel preparation method. Polyp detectability of the CTC using this method and the acceptability of the preparation were also investigated. The volume of residual fluid in the colon with this method was smaller than that with the conventional method. The CT value of the residual fluid with this method was higher than that with the conventional method. Visual assessment of the quality of stool tagging with this method gave similar results to those obtained using the conventional method. The sensitivities were 95% for 5–10 mm polyps and 100% for polyps larger than 10 mm. The PPVs were 91% for 5–10 mm polyps and 100% for polyps larger than 10 mm. These results appear to be as good as in previous reports. In the questionnaires, about 80% of the answers were favorable regarding the volume and the taste of laxative. We conclude that LVSD bowel preparation method for CTC maintains polyp detectability and is better tolerated.
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Data
  • Photon Mass Energy Transfer Coefficients for Elements Z=1 to 92 and 48 Additional Substances of Dosimetric Interest
    Hideki Kato
    2014 Volume 70 Issue 7 Pages 684-691
    Published: 2014
    Released on J-STAGE: July 23, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.7.684
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    Photon mass energy transfer coefficient is an essential factor when converting photon energy fluence into kinetic energy released per unit mass (kerma). Although mass attenuation coefficient and mass energy absorption coefficients can be looked up in databases, the mass energy transfer coefficient values are still controversial. In this paper, the photon mass energy transfer coefficients for elements Z=1–92 were calculated based on cross-sectional data for each photon interaction type. Mass energy transfer coefficients for 48 compounds and/or mixtures of dosimetric interest were calculated from coefficient data for elements using Bragg’s additivity rule. We additionally developed software that can search these coefficient data for any element or substance of dosimetric interest. The database and software created in this paper should prove useful for radiation measurements and/or dose calculations.
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Special Article for Vol. 70
Educational Lecture—Monte Carlo Simulation for Radiological Technology
Basic Lecture—Image Reconstruction: Basic and Clinical Application
Basic Lecture—Disease of the Brain: From Diagnosis to Treatment
JIRA Topics
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