Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 70, Issue 3
Displaying 1-19 of 19 articles from this issue
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Opening Article
Originals
  • Development of a Digital Chest Phantom for Studies on Energy Subtraction Techniques
    Norio Hayashi, Anna Taniguchi, Kimiya Noto, Masayuki Shimosegawa, Tosh ...
    2014 Volume 70 Issue 3 Pages 191-198
    Published: March 20, 2014
    Released on J-STAGE: March 20, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.3.191
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    Digital chest phantoms continue to play a significant role in optimizing imaging parameters for chest X-ray examinations. The purpose of this study was to develop a digital chest phantom for studies on energy subtraction techniques under ideal conditions without image noise. Computed tomography (CT) images from the LIDC (Lung Image Database Consortium) were employed to develop a digital chest phantom. The method consisted of the following four steps: 1) segmentation of the lung and bone regions on CT images; 2) creation of simulated nodules; 3) transformation to attenuation coefficient maps from the segmented images; and 4) projection from attenuation coefficient maps. To evaluate the usefulness of digital chest phantoms, we determined the contrast of the simulated nodules in projection images of the digital chest phantom using high and low X-ray energies, soft tissue images obtained by energy subtraction, and “gold standard” images of the soft tissues. Using our method, the lung and bone regions were segmented on the original CT images. The contrast of simulated nodules in soft tissue images obtained by energy subtraction closely matched that obtained using the gold standard images. We thus conclude that it is possible to carry out simulation studies based on energy subtraction techniques using the created digital chest phantoms. Our method is potentially useful for performing simulation studies for optimizing the imaging parameters in chest X-ray examinations.
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  • Triexponential Diffusion Analysis in Invasive Ductal Carcinoma and Fibroadenoma
    Masayuki Nakagawa, Tosiaki Miyati, Tatsuya Hayashi, Syotaro Kanao, Mas ...
    2014 Volume 70 Issue 3 Pages 199-205
    Published: March 20, 2014
    Released on J-STAGE: March 20, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.3.199
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    To simultaneously obtain information on diffusion and perfusion in breast lesions by diffusion-weighted magnetic resonance imaging (DWI), we analyzed three diffusion components using a triexponential function. Eighteen subjects [10 with invasive ductal carcinoma (IDC), 8 with fibroadenoma] were evaluated using DWI with multiple b-values. We derived perfusion-related diffusion, fast free diffusion, and slow restricted diffusion coefficients (Dp, Df, Ds) calculated from the triexponential function using the DWI data. Moreover, the triexponential analysis was compared with biexponential and monoexponential analyses. Each diffusion coefficient with a triexponential function was correlated to a relative enhancement ratio (RER) using dynamic contrast-enhanced MRI. In triexponential analysis, Dp and Ds in IDC were significantly higher than those for fibroadenoma. There was no correlation between each diffusion coefficient from the triexponential analysis in any of the groups (Dp, Df, and Ds), but biexponential analysis revealed a positive correlation between each diffusion coefficient in breast lesions. Strong correlations were found between Dp and RERs. Triexponential analysis thus makes it possible to obtain, in noninvasive fashion, more detailed diffusion and perfusion information in breast lesions.
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  • Development of an Attitude-measurement Questionnaire Using the Semantic Differential Technique: Defining the Attitudes of Radiological Technology Students toward X-ray Examination
    Naomi Tamura, Takayoshi Terashita, Katsuhiko Ogasawara
    2014 Volume 70 Issue 3 Pages 206-212
    Published: March 20, 2014
    Released on J-STAGE: March 20, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.3.135
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    Background: In general, it is difficult to objectively evaluate the results of an educational program. The semantic differential (SeD) technique, a methodology used to measure the connotative meaning of objects, words, and concepts, can, however, be applied to the evaluation of students’ attitudes. In this study, we aimed to achieve an objective evaluation of the effects of radiological technology education. We therefore investigated the attitude of radiological students using the SeD technique. We focused on X-ray examinations in the field of radiological technology science. Methods: Bipolar adjective scales were used for the SeD questionnaire. To create the questionnaire, appropriate adjectives were selected from past reports of X-ray examination practice. The participants were 32 senior students at Hokkaido University at the Division of Radiological Technology at the School of Medicine’s Department of Health Sciences. All the participants completed the questionnaire. The study was conducted in early June 2012. Attitudes toward X-ray examination were identified using a factor analysis of 11 adjectives. Results: The factor analysis revealed the following three attitudes: feelings of expectation, responsibility, and resistance. Knowledge regarding the attitudes that students have toward X-ray examination will prove useful for evaluating the effects of educational intervention. In this study, a sampling bias may have occurred due to the small sample size; however, no other biases were observed.
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  • Indirect Method of Measuring the Scatter X-ray Fraction Using Collimators in the Diagnostic Domain
    Hiroaki Hayashi, Kazuki Takegami, Yuki Konishi, Ikuma Fukuda
    2014 Volume 70 Issue 3 Pages 213-222
    Published: March 20, 2014
    Released on J-STAGE: March 20, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.3.213
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    The lead disc method is conventionally applied to measure the scatter fraction directly in the energy range of diagnostic X-rays. There are numerous reports of use of this method, but it is difficult to make lead discs with sufficient fabrication accuracy. In this paper, we newly propose an indirect measurement method using collimators instead. In our method, we measure the following two experimental values: the sum of the intensities of the direct X-rays and scattered X-rays, and the intensity of direct X-rays using lead collimators. The ratio of these two values shows the fraction of the direct X-ray that is the complementary value of the scatter fraction. To verify this method experimentally, we carried out experiments using a computed radiography system at tube voltages of 40 kV to 100 kV, and phantom thicknesses of 10 mm to 100 mm. The results confirmed the validity of our method.
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Note
  • Development of a Computer-aided Diagnostic System for Detecting Multiple Sclerosis Using Magnetic Resonance Images
    Susumu Tachinaga, Yuuki Hiura, Ikuo Kawashita, Yasuhiko Okura, Takayuk ...
    2014 Volume 70 Issue 3 Pages 223-229
    Published: March 20, 2014
    Released on J-STAGE: March 20, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.3.223
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    It is of key importance to be able to evaluate the temporal changes seen in multiple sclerosis (MS) lesions in terms of location, shape, and area for estimating MS progression. The purpose of our study was to develop an automated method for detecting potential MS regions based on three types of brain magnetic resonance (MR) images: T1- and T2-weighted images, and fluid attenuated inversion-recovery (FLAIR) images. The brain regions were segmented based on a tri-linear interpolation technique and k-mean clustering technique. True positive regions and false positive regions were classified from three types of MR images using a support vector machine (SVM). We applied our proposed method to 60 slices of 20 MS cases. As a result, the sensitivity for detection of MS regions was 81.8%, with 14.1% false positives per true positive. This method should prove useful for the diagnosis of multiple sclerosis.
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Clinical Technology
  • Verification of the Dose from an Iridium-192 (192Ir) Sealed Source Absorbed by an Implantable Cardioverter Defibrillator (ICD) during Uterine Intracavitary Brachytherapy
    Takaaki Hirose, Yoshiyuki Umezu, Yoshitaka Noguchi, Junichi Fukunaga, ...
    2014 Volume 70 Issue 3 Pages 230-234
    Published: March 20, 2014
    Released on J-STAGE: March 20, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.3.230
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    The purpose of this study was to verify the dose absorbed by an implantable cardioverter defibrillator (ICD) from an 192Ir sealed source during uterine intracavitary brachytherapy, and to confirm its immunity to radiation effects. First, prior to treatment, the doses around the ICD position of an anthromorphic phantom were evaluated. Next, we also measured the dose at the ICD position using a fluorescent glass dosimeter and silicon diode dosimeter during the treatment of intracavitary brachytherapy of a patient implanted with an ICD. The results of the phantom study showed the dose percentage at the ICD location, 2 cm deep, to be 0.074% of the prescribed dose. The results of a treatment study similarly showed the dose, measured using a fluorescent glass dosimeter in the ICD position, to be 0.071% of the prescribed dose. During the application of the total prescribed dose, 30 Gy/5 fraction, the dose at the surface of the ICD position was estimated to be 21.2 mGy, well below the 1 Gy maximum recommended in the JASTRO guidelines. We regard dose verification and monitoring during treatment to be both necessary and useful in the treatment of individual cases.
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Data
  • A Survey Report on Magnetic Resonance Equipment Damage in Areas in Miyagi Prefecture Affected by the Great East Japan Earthquake
    Fumio Maeyatsu, Yoshihiro Abe, Makoto Hishinuma, Takeo Hikiti, Hajime ...
    2014 Volume 70 Issue 3 Pages 235-241
    Published: March 20, 2014
    Released on J-STAGE: March 20, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.3.235
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    A questionnaire comprising 14 items, inquiring about the state of damage, whether safety could be ensured, and progress of repair and restoration was distributed to 984 facilities in seven prefectures on the Pacific coast as part of a fact-finding survey of damage caused to magnetic resonance (MR) devices by the Great East Japan Earthquake. In all, 458 responses (46.6%) were collected. In Miyagi Prefecture alone, 65 responses from 105 questionnaires were collected (response rate: 61.9%). The overall incidence of damage was 19.2%, with 57 facilities (12.4%) reporting that displacement of the magnets was the most common problem. The damage event rate in Miyagi Prefecture was 51.3%, with displacement of the magnet being highest at 17 cases (26.2%). There was a high rate of 13 cases (26.5%) of chiller and air conditioning failures and a rapid loss of He in ten MR scanners (20.4%). Notably, 87.8% of facilities in Miyagi Prefecture (24.5% of the total) were affected by earthquakes exceeding 6 on the Japanese Seismic Intensity Scale. Flood damage caused by the tsunami was also seen along the Sanriku coast to Sendai City (six MR scanners, 50% of the total), and was typical of the damage seen in Miyagi Prefecture.
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  • Telephone Consultations on Exposure to Nuclear Disaster Radiation
    Sachiko Yashima, Koichi Chida
    2014 Volume 70 Issue 3 Pages 242-249
    Published: March 20, 2014
    Released on J-STAGE: March 20, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.3.242
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    The Fukushima nuclear disaster occurred on March 11, 2011. For about six weeks, I worked as a counselor for phone consultations regarding radiation risk. I analyzed the number of consultations, consultations by telephone, and their changing patterns with elapse of time, to assist with consultations about risk in the future. There were a large number of questions regarding the effects of radiation, particularly with regard to children. We believe that counseling and risk communication are the key to effectively informing the public about radiation risks.
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Work in Progress
  • Quality Assessment of X-ray Images Using Modulation Transfer Function Fractal Dimension
    Shun Endo, Yongbum Lee, Du-Yih Tsai, Takeshi Hara
    2014 Volume 70 Issue 3 Pages 250-253
    Published: March 20, 2014
    Released on J-STAGE: March 20, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.3.250
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    Objective evaluation, e.g., using the modulation transfer function (MTF) or the noise power spectrum (NPS) of an X-ray imaging system may not correctly correspond to the subject’s evaluation, e.g., when using the receiver operating characteristic (ROC). Moreover, it is difficult to measure MTF or NPS from clinical images. We therefore applied MTF fractal dimension to an X-ray imaging system. The MTF fractal dimension includes the frequency properties of the human eye in addition to quantitative complexity. In this study, we demonstrated a relationship between basic image quality and MTF fractal dimension using simulated and actual X-ray images.
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  • A Detection Method for Blurred Regions in Radiographs
    Tomoya Muroi, Yongbum Lee, Du-Yih Tsai, Masaki Tsurumaki
    2014 Volume 70 Issue 3 Pages 254-257
    Published: March 20, 2014
    Released on J-STAGE: March 20, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.3.254
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    In this paper, we propose a detection method for blurred regions in radiographs. The method involves edge detection using a Sobel filter, manually determining the region of interest (ROI), feature calculation, and classification using a support vector machine. We applied our method to 14 phantom images (7 normal images, 7 blurred images) and 14 clinical images (12 normal images, 2 blurred images). As a result, the average classification accuracies of ROIs with blurring and ROIs without blurring were 98% and 90% for phantom images and clinical images, respectively.
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Special Article for Vol. 70
Basic Lecture—Three-dimensional Computer Graphics
Basic Lecture—Heart Disease: From Diagnosis to Treatment
Basic Lecture—Image Reconstruction: Basic and Clinical Application
Science Exchanges Committee Report
Committee News
JIRA Topics
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