Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 65, Issue 10
Displaying 1-15 of 15 articles from this issue
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Opening Article
Originals
  • Influence of Position of Ionization Chamber and Leaf-end on Verification Value in IMRT Verification for Prostate Cancer
    Harumitsu Hashimoto, Hisato Nagano, Masahiro Katou, Masanori Nakanishi ...
    2009 Volume 65 Issue 10 Pages 1369-1377
    Published: October 20, 2009
    Released on J-STAGE: November 05, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.1369
    JOURNAL FREE ACCESS
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    In IMRT for prostate cancer, MU verification is performed by the actual measurement. We have experienced a remarkable improvement in results, once succeeding in finding out the more suitable and optimal evaluation dose point in some cases even though the deviation between a designed MU score and our actual record gained at the iso-center was more than 3%. In this study, we tried to demonstrate how much influence would be given to the point dose verification by the 3D arrangement between an ion chamber and tips of the MLC. The five cases in which the bias between each actual datum and planed MU score showed that about 3% were picked up and through these MLC configurations, 8 leaf-ends around the chamber were highlighted as the influential ones. After each distance from 4 pairs, a total of 8 leaves to the axis (the mid-line) of our ion chamber were mapped. The indexes (PlanLeafScores) were computed through these distances and segmental MU scores. The ratio of these scores and results obtained at the 12 sites within 1 cm from the iso-center were carried out by single regression analysis. In all cases the ratios of planed MU values to the actual ones tended to go down in inverse proportion to the increase in PlanLeafScores (r<-0.77, p<0.002). As the dimensional arrangement between the ion chamber and the edges of the MLC were thought to determine the result of the verification. PlanLeafScores will enable us to determine the optimal evaluation of the dose point.
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  • Evaluation of Factor for One-point Venous Blood Sampling Method Based on the Causality Model
    Norikazu Matsutomo, Kouichi Kobara, Fumie Sasaki, Haruo Watanabe, Akio ...
    2009 Volume 65 Issue 10 Pages 1378-1384
    Published: October 20, 2009
    Released on J-STAGE: November 05, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.1378
    JOURNAL FREE ACCESS
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    Purpose: One-point venous blood sampling method (Mimura, et al.) can evaluate the rCBF value with a high degree of accuracy. However, the method is accompanied by complexity of technique because it requires a venous blood Octanol value, and its accuracy is affected by factors of input function. Therefore, we evaluated the factors that are used for input function to determine the accuracy input function and simplify the technique. Methods: The input function which uses the time-dependent brain count of 5 minutes, 15 minutes, and 25 minutes from administration, and the input function in which an objective variable is used as the artery octanol value to exclude the venous blood octanol value are created. Therefore, a correlation between these functions and rCBF value by the MS method is evaluated. Results: Creation of a high-accuracy input function and simplification of technique are possible. The rCBF value obtained by the input function, the factor of which is a time-dependent brain count of 5 minutes from administration, and the objective variable is artery octanol value, had a high correlation with the MS method (y=0.899x+4.653, r=0.842).
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  • Hierarchy Structuring for Mammography Technique by Interpretive Structural Modeling Method
    Nozomi Kudo, Kunio Kurowarabi, Takayoshi Terashita, Naoki Nishimoto, K ...
    2009 Volume 65 Issue 10 Pages 1385-1390
    Published: October 20, 2009
    Released on J-STAGE: November 05, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.1385
    JOURNAL FREE ACCESS
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    Participation in screening mammography is currently desired in Japan because of the increase in breast cancer morbidity. However, the pain and discomfort of mammography is recognized as a significant deterrent for women considering this examination. Thus quick procedures, sufficient experience, and advanced skills are required for radiologic technologists. The aim of this study was to make the point of imaging techniques explicit and to help understand the complicated procedure. We interviewed 3 technologists who were highly skilled in mammography, and 14 factors were retrieved by using brainstorming and the KJ method. We then applied Interpretive Structural Modeling (ISM) to the factors and developed a hierarchical concept structure. The result showed a six-layer hierarchy whose top node was explanation of the entire procedure on mammography. Male technologists were related to as a negative factor. Factors concerned with explanation were at the upper node. We gave attention to X-ray techniques and considerations. The findings will help beginners improve their skills.
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  • Feasibility of a New Initial Check-up Program for Medical X-ray and Computed Radiography Systems
    Keiji Fujimoto, Nobuhiro Oda, Yuusuke Jinnai, Etsurou Futagami, Seiich ...
    2009 Volume 65 Issue 10 Pages 1391-1399
    Published: October 20, 2009
    Released on J-STAGE: November 05, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.1391
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    We investigated the feasibility of a simple, easy method that uses a digital radiography (DR) phantom for daily operational checks of the medical X-ray system and computed radiography (CR) system. First, we measured exposure indicator calibration (S value) from 12 seconds to 11 minutes after irradiation to examine the effect of fading of the photostimulable phosphor screen. We then examined the management width of the exposure indicator calibration ratio and limiting resolution of the CR system. Finally, we studied the exposure indicator calibration ratio, limiting the resolution and time necessary for the initial check-up by running the program 20 times for five weeks. Under the influence of the fading, the S value increased gradually, although the level of variation was small. From the mean and coefficient of variation of the exposure indicator calibration ratio, the management width was determined as ±10%. The exposure indicator calibration ratio and limiting resolution were within ±10% and ±20%, respectively. It took three minutes to accomplish the initial check-up. The initial check-up using a DR phantom is simple and can perform the operational check of the medical X-ray system and the CR system with sufficient accuracy in only 3 minutes.
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Note
  • Development of Computer Code, SDEC, for Evaluation of Patient Surface Dose from Diagnostic X-ray
    Hideki Kato, Shigehisa Fujii, Yuji Yoshimi
    2009 Volume 65 Issue 10 Pages 1400-1406
    Published: October 20, 2009
    Released on J-STAGE: November 05, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.1400
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    It is important to precisely evaluate patient dose from a diagnostic X-ray in order to investigate medical exposure reduction. As a method of evaluating patient surface dose, computation with existing data based on exposure in air is generally used. With this method, backscatter factors and absorbed dose conversion factors are given by the parameter of the effective energy or the half value layer, making this procedure complicated. We developed program software (Surface Dose Evaluation Code, SDEC) that computes the surface dose automatically, using the backscatter factor and absorbed dose conversion factor calculated by using X-ray spectral data. Because the measurement of effective energy or a half value layer is unnecessary, SDEC is a useful evaluation method.
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Clinical Technology
  • Determination of Joint Contact Area Using MRI
    Hidenori Yoshida, Koichi Kobayashi, Makoto Sakamoto, Yuji Tanabe
    2009 Volume 65 Issue 10 Pages 1407-1414
    Published: October 20, 2009
    Released on J-STAGE: November 05, 2009
    DOIhttps://doi.org/10.6009/jjrt.65.1407
    JOURNAL FREE ACCESS
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    Elevated contact stress on the articular joints has been hypothesized to contribute to articular cartilage wear and joint pain. However, given the limitations of using contact stress and areas from human cadaver specimens to estimate articular joint stress, there is need for an in vivo method to obtain such data. Magnetic resonance imaging (MRI) has been shown to be a valid method of quantifying the human joint contact area, indicating the potential for in vivo assessment. The purpose of this study was to describe a method of quantifying the tibiofemoral joint contact area using MRI. The validity of this technique was established in porcine cadaver specimens by comparing the contact area obtained from MRI with the contact area obtained using pressure-sensitive film (PSF). In particular, we assessed the actual condition of contact by using the ratio of signal intensity of MR images of cartilage surfaces. Two fresh porcine cadaver knees were used. A custom loading apparatus was designed to apply a compressive load to the tibiofemoral joint. We measured the contact area by using MRI and PSF methods. When the ratio of signal intensity of the cartilage surface was 0.9, the error of the contact area between the MR image and PSF was about 6%. These results suggest that this MRI method may be a valuable tool in quantifying joint contact area in vivo.
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The 64th Annual Scientific Congress
The 65th Annual Scientific Congress
Basic Lecture—Physical Image Quality Assessment in Digital Radiography
Basic Lecture—How to Make Use of Softwares
Clinical Technology Course
JIRA Topics
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