Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 68, Issue 5
Displaying 1-15 of 15 articles from this issue
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Opening Article
Originals
  • Development of Counting Method of Black Spots Caused by the Radioactive Contaminations on the Imaging Plate
    Hiroaki Hayashi, Sadamitsu Nishihara, Yoji Onuma
    2012 Volume 68 Issue 5 Pages 545-553
    Published: May 20, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.5.545
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    Due to accidents of the nuclear power plants in Fukushima prefecture, a lot of radioisotopes were diffused into the environment. They adhered onto the surface of the X-ray detector (imaging plate; IP) and many black spots were seen on the medical images. The process to count them is important to evaluate the degree of contamination and/or removal. In this study, we aimed to develop a counting method for black spots. Based on the analysis of the medical images having black spots, we summarized that areas affected by the certain black spots were limited to the eight pixels surrounding the most intensive pixel. The newly developed counting method was applied to these nine pixels (3×3 pixels) and selection rules were based on the following two information: 1. differences between the digital value of the most intensive pixel and those of the surrounding eight pixels, and 2. total summation of the digital values in the nine pixels. The estimated image based on our method showed a good concordance with the original image. Therefore, we summarized that our counting method is a powerful tool for estimating numbers of black spots.
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  • Evaluation of Inhibiting the Effect of Flow Artifact in Radial Scan
    Kasumi Terauchi, Tsuyoshi Ueyama,, Yasunobu Fukunishi
    2012 Volume 68 Issue 5 Pages 554-562
    Published: May 20, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.5.554
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    Radial scan method collects blades rotated about the k-space origin. The one blade is the group of the echo acquired each repetition time (TR) in concentric strips. Because each of the blades has the phase-encode direction, it can be expected to be dispersing flow artifact which appear in the phase-encode direction. We examined how to produce flow artifact in radial scan method without motion correction. Flow artifact does not appear like a mass in radial scan method. Background noise in radial scan method tended to decrease when width of the blade is thinner and a number of blades is larger under a number of echo is keeping. In conclusion, unlike past countermeasures against flow artifact in Cartesian method, flow artifact becomes inconspicuous to be dispersed by 360 degrees in radial scan method.
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  • Evaluation of Edge Enhancement Effect of Phase Contrast Imaging Using Newly-developed Photostimulable Phosphor Plate
    Satoru Matsuo, Junji Morishita, Tetsuro Katafuchi, Hiroshi Fujita
    2012 Volume 68 Issue 5 Pages 563-572
    Published: May 20, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.5.563
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    We investigated whether the use of a newly developed columnar-crystal-type photostimulable-phosphor plate (CP1M200, referred to as system C) helps to provide improved edge-enhanced effect in phase contrast imaging. Physical characteristics of 2 conventional particulate-crystal-type photostimulable-phosphor plates (RP-5PM, referred to as system A and RP-6M, referred to as system B) and system C were measured. Then, an acrylic plate phantom and RMI152 phantom were imaged using 3 types of plates, and the edge-enhancement effects were evaluated based on the profile curve of the acrylic plate phantom. Visual evaluation of the RMI152 phantom images was conducted. The results showed that the modulation transfer function (MTF) of system C was superior to those of the other systems. The WS of system C was superior to those of the other systems in the low frequency band region, and inferior to those of the other systems in the high frequency band region. The presence of an edge-enhanced image was not detectable in the profile curve of the acrylic plate in system A, although that was shown in systems B and C due to their excellent sharpness. In the visual image evaluation of the RMI152 phantom, image quality of system C was superior to those of the other systems. Phase contrast imaging with a digital detector of a columnar-crystal-type photostimulable-phosphor plate is considered to provide improved edge-enhancement over that of conventional plates.
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  • Application of Collimator Broad Correction Three Dimensional Ordered Subsets Expectation Maximization for Regional Cerebral Blood Flow Measurement
    Mami Okada, Masuo Hayashi, Hisashi Tsuji, Hiroyuki Akagi, Katsuyoshi O ...
    2012 Volume 68 Issue 5 Pages 573-583
    Published: May 20, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.5.573
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    Autoradiography (ARG) has been used for quantitative analysis of the cerebral blood flow using 123I-IMP, and the regional cerebral blood flow (rCBF) can be assessed more accurately with scatter and attenuation correction. Currently, the filtered back projection (FBP) method is generally used for image reconstruction. However, we anticipate obtaining more accurate rCBF by the ordered subsets expectation maximization method with collimator broad correction three dimensional ordered subsets expectation maximization (3D-OSEM). In the present study, we optimized the processing conditions to quantify rCBF using the 3D-OSEM method and compared them with the FBP method. Regarding the method, we determined the subsets and iteration, compared rCBF values using a profile curve, and compared them with the rCBF values obtained by the XeCT (Xenon-enhanced computed tomography)/CBF method. We found that in the 3D-OSEM method using 90 direction collection and 1.72 mm/pixel, the most accurate image was obtained around subset 9 and iteration 10. In addition, as compared to the profile curve and the XeCT/CBF method, the thalamus rCBF was high in the 3D-OSEM method with a good correlation with that of the XeCT/CBF. Accordingly, we concluded that the 3D-OSEM method can improve the decrease in rCBF due to blurring of the distance between the source (i.e., a structure located in the central part of the brain such as the thalamus and the collimator).
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  • Relationship between the Effect of Medial Rotation of the Foot Axis by Ankle Dorsiflexion and the Ability to Visualize the Femoral Neck Axis in the Hip Joint Anterio-posterior Radiography: Evaluation by Magnetic Resonance Images
    Takashi Hashido, Tsukasa Doi, Hiroaki Matsuzawa, Kiyosumi Kawamoto
    2012 Volume 68 Issue 5 Pages 584-592
    Published: May 20, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.5.584
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    In scanning of the hip joint anterio-posterior radiography, by changing the lower extremities to the extension position and moving the foot axis (base line of the foot) by medial rotation, the angle of anteversion of the femoral neck is corrected. In this study, we assessed the effects on medial rotation of the femoral neck when keeping the planta vertically-positioned by ankle dorsiflexion (intermediate position of the ankle) and making change of the medial rotation angle of the foot axis by scanning the magnetic resonance (MR) images of knee joints and hip joints. The subjects in this study were 12 males (age: 37.9±13.8, weight: 67.3±5.5 kg) and 7 females (age: 27.6±5.1, weight: 50.0±4.5 kg). We measured the medial rotation angles of knee joints and femoral necks on MR images. Also, differences of these angles between males and females were compared. Although the gender differences were not found in medial rotation angle of both joints at all leg positions (P>0.05), the medial rotation angles increased by approximately 1.5 to 2.0 times larger by putting them at the intermediate position, and there were significant differences between the naturally plantar-flexed position and the intermediate position (P<0.05). In conclusion, our results showed that the optimal leg position for correcting the angle of anteversion was 20 degrees medial rotation of the foot axis at the naturally plantar-flexed position, or 10 degrees medial rotation of the foot axis at the intermediate position, regardless of gender.
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Notes
  • Electronic Portal Imaging Device (EPID) Portal Image Filtering for Simplifying Registration on Radiation Therapy
    Masanori Yamada, Masaki Ohkubo, Akihiro Kayugawa, Hiromi Yamada, Masat ...
    2012 Volume 68 Issue 5 Pages 593-601
    Published: May 20, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.5.593
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    A simple method for improving the quality of electronic portal imaging device (EPID) portal images was proposed for the reduction of the burden on the registration between digital reconstruction radiography (DRR) and EPID portal images in radiation therapy. Conventional image filtering techniques in the spatial-frequency domain are applied to the proposed method. While a band-pass filter (BPF) is employed to extract spatial-frequency components included in the bone edge, a high-pass filter (HPF) is employed to obtain the effect corresponding to the general dynamic range compression. The band-pass filtered image is weighted by a parameter for adjusting the bone edge enhancement, and is added to the high-pass filtered image. This method was applied to the portal images in the neck region. In the image obtained by the proposed filtering, the bone edge was clearly observed. In addition, soft tissue structures were identified in the same display settings (window level/width; WL/WW) as the bone edge observation; that is, the adjustment of the display settings was not required for the observation of each object. These results suggested that both bone edge enhancement and dynamic range compression would be achieved successfully. It was estimated that the images obtained by the proposed method were more appropriate for the registration than conventional portal images, in 47 times registrations of 50 times in total (the registrations by five radiological technologists in ten patients). The proposed method was concluded to be useful for improving the quality of portal images, enabling the efficient registration.
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  • Analysis of Statistical Significance for Difference of Setup Error between Staff and New Face in Radiotherapy
    Hiroko Yamaguchi, Mitsuhiro Matsumoto, Seiichi Ohta, Takahiko Ueda, Ya ...
    2012 Volume 68 Issue 5 Pages 602-607
    Published: May 20, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.5.602
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    Introduction: We verified the setup error (SE) in two persons’ radiation therapist’s team, which consist of staff and new face. We performed the significance test for SE by the staff group and the new face group. Methods: One group consists of four staff therapists with at least 5 to 30 years of experience. The other group consists of new face radiation therapists that have 1 to 1.5 years of experience. Analyzed were 53 patients diagnosed with pelvic cancer (seven patients who underwent 3 dimensional conformal radiation therapy (3DCRT) and 46 patients who underwent intensity modulated radiation therapy (IMRT). Image verification was 1460 times. It was performed through setup verification by cone beam computed tomography (CBCT), and we measured SE of four directions (lateral, long, vertical, 3D). We performed the student’s t-test to get the difference of the average error between the staff group and the new face group. Results: The results of significance tests show that there is no difference between SE in the staff group and the new face group in radiotherapy.
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Data
  • Difference by Level of Awareness and the Years of Experience to Patient Treatment Safety
    Tsukasa Doi, Kiyosumi Kawamoto, Kazuya Yamaguchi
    2012 Volume 68 Issue 5 Pages 608-616
    Published: May 20, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.5.608
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    According to the report of the reporting project of medical accidents (from July 2010 to March 2011) which was issued by the Ministry of Health, Labour, and Welfare, a lot of incidents involving radiological technologists occurred among young ages or experienced ages; therefore, we focused on this matter. We carried out questionnaires for the radiological technologists at the radiology department of our hospital to see how concerned they are about the patient treatment safety. We examined the causal relationship between years of their experience and their concerns about the patient treatment safety. As a result, we found that their concerns about the patient treatment safety are characteristically different depending on the years of experience. The results showed that the new technologists were on a low level of caring with a similar philosophy to the saying “To err is human”. They also lack a positive attitude. Moreover, they stated that the causes of the errors were neither the devices nor the system of the devices. Mid-career technologists stated that the most common cause of errors is the liability of the person concerned. They are concerned that education to improve individual abilities is important. Experienced technologists stated that the cause of the error is excluding the person concerned, but due to the devices, patients, or advanced specialization of the examinations. However, they also had the positive attitude to promote the patient treatment safety.
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The 39th Autumn Scientific Congress
Educational Lecture–Radiation Measurement in the Clinical Setting
Basic Lecture–Radiation Therapy Technology: Basic Strategy
Series–From Diagnosis of the Breast to Treatment
Science Exchanges Committee News
JIRA Topics
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