Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 65, Issue 5
Displaying 1-22 of 22 articles from this issue
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Opening Article
Originals
  • Development of Fat Suppressed Three-dimensional T1-weighted Image Using Linear Filling Order for K-space
    Tomoyuki Okuaki, Shutaro Saiki, Tetsuo Ogino, Akira Suwa, Marc Van Cau ...
    2009 Volume 65 Issue 5 Pages 585-593
    Published: May 20, 2009
    Released on J-STAGE: June 04, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.585
    JOURNAL FREE ACCESS
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    We have developed a sequence for abdominal examination that fat suppressed 3D-T1W by a linear filling order using an adiabatic pulse for frequency selective fat suppression. We simulated the change in fat signal using a linear method and checked the starting point of data filling for the null point using a phantom of different T1 values. We then checked the contrast between the fat signal and liver. After checking by using simulation, a clinical evaluation was done. The change in fat signal was mostly the same after the fourth shot, and we were able to estimate the null point of the fat signal by the following parameters: TR, FA, TFE factor, and shot interval. Consequently, we could control the starting point of data filling in k-space for fat suppression. The contrast between fat and liver was improved because noise was reduced by the linear method. The sequence developed with the linear filling order using frequency selective fat suppression pulse proved to be useful.
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  • Estimation of Effective Dose to Salivary Glands at Examination of the Oral and Maxillofacial Region
    Tsuneichi Okano, Ayae Matsuo, Kenichi Gotoh, Midori Yokoi, Akiko Hiruk ...
    2009 Volume 65 Issue 5 Pages 594-602
    Published: May 20, 2009
    Released on J-STAGE: June 04, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.594
    JOURNAL FREE ACCESS
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    The salivary glands and the oral mucosa were included in the determination of effective doses of radiography in the new ICRP (International Commission on Radiological Protection) recommendations. These changes will likely result in an upward reassessment of the effective dose during oral and maxillofacial radiographic examination. We measured the dose received by many organs and calculated the effective doses using the guidelines in ICRP Publications 103 and 60. For this study, we used intraoral radiography (incisor, canine, premolar, molar, maxillary, and mandibular areas) and panoramic radiography. The two levels of effective doses were compared. As a result, exposure during intraoral radiography ranged from 4 to 8 μSv and that during panoramic radiography ranged from 16 μSv in Publication 103. Effective doses in Publication 103 were higher than those in Publication 60. The dose was 1.6–4.5 times higher in intraoral radiography and 2.2 times higher in panoramic radiography. In conclusion, the salivary glands markedly influenced the value of the effective doses of radiography in this study.
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  • Development of a New Method to Estimate Patient Surface Dose Distributions in IVR
    Tomokazu Shohji, Yoko Katsuki, Shinichi Yamashita, Hideki Kato
    2009 Volume 65 Issue 5 Pages 603-611
    Published: May 20, 2009
    Released on J-STAGE: June 04, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.603
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    Recently, the angiography system used for interventional radiology (IVR) provides a device for measuring dose-area product (DAP), which is compulsory in European countries. The usefulness of DAP is that one can observe patient dose in real time during IVR and can obtain an integral dose by overall IVR procedure without a dosimeter directly placed on a patient. It is important to know the most irradiated region (hot spot) of the patient’s skin and its maximum value in the dose management of IVR, but this information cannot be obtained only in DAP. In this paper, we describe a new method to estimate patient surface dose distributions in IVR. We devised a sheet dubbed the “Number map”, which does not obstruct the IVR procedure, to confirm the hot spot, and we developed software (named PIETA “Patient Information on Exposure Total Dose Analysis in IVR”) to analyze the data from the Number map. Using this system, dose distributions of patient’s skin were easily obtained, and we could easily perform patient dose management in IVR.
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Clinical Technology
  • Optimization of Dark-blood T2-weighted Sequence in Myocardium Magnetic Resonance Imaging
    Hiroyuki Sugimori, Takahiro Uno, Akira Yanagisawa
    2009 Volume 65 Issue 5 Pages 612-619
    Published: May 20, 2009
    Released on J-STAGE: June 04, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.612
    JOURNAL FREE ACCESS
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    The evaluation of myocardium characterization is an important role in cardiac MRI. The dark-blood (DB) sequence is used for non-enhanced T2-weighted myocardial images. The purpose of this study was to evaluate and optimize the DB T2WI sequence in myocardium images. We changed the parameters TE, echo train length (ETL), inversion time (TI), and fat suppression method, respectively. Data acquisition with end-diastolic phase was effective for avoiding the blur that was caused by cardiac motion. Consequently, the optimal setting of ETL and TI was important for myocardial images. STIR was suitable for fat suppression in unstable susceptibility. Setting the parameters synchronized with the cardiac cycle provided optimal myocardial images in DB T2WI.
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  • Observer Performance of PACS-oriented Digitized Mammography in the Detection of Fibrils, Microcalcifications, and Masses: a Phantom Study
    Sachiko Yamada, Takashi Ueguchi, Naoki Mihara, Hiroaki Matsuzawa, Yosh ...
    2009 Volume 65 Issue 5 Pages 620-625
    Published: May 20, 2009
    Released on J-STAGE: June 04, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.620
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    The film digitizer plays an important transitory role as an analog-to-digital bridge for the implementation of PACS on screen-film mammography. The objective of this phantom study was to compare the observer performance of a digitized mammogram on liquid crystal displays (LCDs) with that of the original film mammogram, and to clarify which matrix size of LCDs is adequate for the interpretation of digitized mammography. The American College of Radiology mammographic accreditation phantom containing variously sized fibrils, simulated microcalcifications, and tumor-like masses was radiographed with a screen-film mammographic system. The original film was digitized with a sampling pitch of 50 μm and a density depth of 12 bit. Six observers who were trained in mammography individually viewed digitized images on LCDs and original film. Observer performance of a digitized mammogram with a 2-megapixel LCD was compared with that of original film. The observers were asked to rate the detectability of each test object according to a three-point scale (obviously visible=2, barely detectable=1, undetectable=0). The difference in the mean score between two systems at each object was evaluated by the Wilcoxon’s test. In addition, the dependence of observer performance on the matrix size of LCDs ranging from 1-to 5-megapixel was tested with Scheffé’s multiple comparison. The observers also judged the detectability according to the three-point scale. The results show that the digitized mammogram provides acceptable but slightly inferior detectability than original film. There was no dependence of matrix size in observer performance with more than 2-megapixel LCDs.
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Work in Progress
  • Optimal Scan Timing for Gd-EOB-DTPA Enhanced Liver Dynamic MR Imaging
    Satoru Akimoto, Hiroshige Mori, Tomonori Fujii, Ken Furuya
    2009 Volume 65 Issue 5 Pages 626-630
    Published: May 20, 2009
    Released on J-STAGE: June 04, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.626
    JOURNAL FREE ACCESS
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    Gadoxetate Sodium (Gd-EOB-DTPA, EOB) is a new contrast agent for magnetic resonance (MR) imaging that allows both vascular and hepatobiliary imaging in one examination. Often in the arterial phase, however, appropriate scan timing is missed and contrast enhancement is not enough. In addition, to shorten the complete examination, some studies have been conducted to examine scan timing at the hepatobiliary phase earlier than 20 min after injection. We studied the optimal scan timing both at the arterial and the hepatobiliary phase. It was appropriate that multiphase acquisition of MR imaging at the arterial phase should be aimed around 25 sec after injection. Moreover, the liver-spleen contrast ratio (CL–S) at the hepatobiliary phase was highest at 60 min after injection, and the acquisition of an image earlier than 20 minutes lowered the CL–S. In the future, it is desirable to establish how to use Gd-EOB-DTPA (EOB) for hepatic MR imaging after taking the extent of liver damage into consideration.
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Data
The 35th Autumn Scientific Congress
Basic Lecture—Permanent Implant Brachytherapy of the Prostatic Cancer Using I-125 Radiation Source
Clinical Technology Course
Report from the Scientific Research Group
Science Exchanges Committee News
JIRA Topics
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