Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
Search
Advanced search
OR
Browse
Search
Volume 67, Issue 9
Displaying 1-12 of 12 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
Opening Article
Program of the 39th Autumn Scientific Congress
Originals
  • Optimization of Exposure Conditions for Amorphous Selenium Direct Conversion DR-based Mammography System
    Tokiko Endo, Misaki Shiraiwa, Mikinao Oiwa, Chikako Nishida, Takako Mo ...
    2011 Volume 67 Issue 9 Pages 1151-1163
    Published: September 20, 2011
    Released on J-STAGE: September 22, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1151
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    A new direct-conversion detector for DR mammography has improved the detectability of microcalcifications and masses. Each optimized exposure condition (target/filter combination and tube voltage) was defined through comparison of physical values and visual evaluation on breast specimens using the innovative DR mammography. The contrast-to-noise-ratios (CNRs) of PMMA phantoms of various thicknesses were obtained under a variety of exposure conditions whose average glandular doses (AGDs) were made consistent. Fifty breast specimens were irradiated under these combinations. Visual evaluation was conducted on the images, whose histograms were controlled for consistency. In the phantoms with thicknesses of 20 mm or more, tungsten/rhodium had the highest CNRs of the targets/filters such as molybdenum/molybdenum and molybdenum/rhodium. For visualizing microcalcifications and masses on breast specimens of thicknesses of 35 mm and below, molybdenum/molybdenum was the best. Nevertheless, to obtain better image quality, molybdenum/rhodium was superior for 35–55 mm thickness, and tungsten/rhodium was superior for 55 mm and above under the same AGD, enabling accurate and efficient diagnosis. The study showed that the exposure conditions differ for obtaining the highest CNR using phantoms and those under which breast specimen images allow the most accurate and efficient diagnosis. In addition, image evaluations of the breast specimens allowed optimization of exposure conditions that are closer to those of the actual diagnosis using mammography.
    View full abstract
    Download PDF (1961K)
  • Dosimetric Perturbation due to Scattered Rays Released by a Gold Marker Used for Tumor Tracking in External Radiotherapy
    Kosaku Habara, Tomohiro Shimozato, Yuichi Aoyama, Naoki Hayashi, Keisu ...
    2011 Volume 67 Issue 9 Pages 1164-1173
    Published: September 20, 2011
    Released on J-STAGE: September 22, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1164
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Image-guided radiation therapy using a gold marker-based tumor tracking technique provides precise patient setup and monitoring. However, the marker consists of high-Z material, and the resulting scattered rays tend to have adverse effects on the dose distribution of radiotherapy. The purpose of this study was to evaluate the dosimetric perturbation due to the use of a gold marker for radiotherapy in the lungs. The relative dose distributions were compared with film measurement, Monte Carlo simulation, and XiO calculation with the multi grid superposition algorithm using two types of virtual lung phantoms, which were composed of tough water phantoms, tough lung phantoms, cork boards, and a 2.0-mm-diameter gold ball. No dose increase and decrease in the vicinity of the gold ball was seen in the XiO calculations, although it was seen in the film measurements and the Monte Carlo simulation. The dose perturbation due to a gold marker cannot be evaluated using XiO calculation with the superposition algorithm when the tumor is near a gold marker (especially within 0.5 cm). To rule out the presence of such dose perturbations due to a gold marker, the distance between the gold marker and the tumor must therefore be greater than 0.5 cm.
    View full abstract
    Download PDF (2508K)
  • An Method for Evaluating the Positional Accuracy of a Six-degrees-of-freedom Radiotherapy Couch Using High Definition Digital Cameras
    Akihiro Takemura, Shinichi Ueda, Kimiya Noto, Yuichi Kurata, Saori Sho ...
    2011 Volume 67 Issue 9 Pages 1174-1182
    Published: September 20, 2011
    Released on J-STAGE: September 22, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1174
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Purpose: In this study, we proposed and evaluated a positional accuracy assessment method with two high-resolution digital cameras for add-on six-degrees-of-freedom radiotherapy (6D) couches. Methods and Materials: Two high resolution digital cameras (D5000, Nikon Co.) were used in this accuracy assessment method. These cameras were placed on two orthogonal axes of a linear accelerator (LINAC) coordinate system and focused on the isocenter of the LINAC. Pictures of a needle that was fixed on the 6D couch were taken by the cameras during couch motions of translation and rotation of each axis. The coordinates of the needle in the pictures were obtained using manual measurement, and the coordinate error of the needle was calculated. The accuracy of a HexaPOD evo (Elekta AB, Sweden) was evaluated using this method. Results: All of the mean values of the X, Y, and Z coordinate errors in the translation tests were within ±0.1 mm. However, the standard deviation of the Z coordinate errors in the Z translation test was 0.24 mm, which is higher than the others. In the X rotation test, we found that the X coordinate of the rotational origin of the 6D couch was shifted. Conclusions: We proposed an accuracy assessment method for a 6D couch. The method was able to evaluate the accuracy of the motion of only the 6D couch and revealed the deviation of the origin of the couch rotation. This accuracy assessment method is effective for evaluating add-on 6D couch positioning.
    View full abstract
    Download PDF (1066K)
  • A New Method of Measuring Effective Energy Using Copper-pipe Absorbers in X-ray CT
    Hiroji Iida, Kimiya Noto, Wataru Mitsui, Tadanori Takata, Tomoyuki Yam ...
    2011 Volume 67 Issue 9 Pages 1183-1191
    Published: September 20, 2011
    Released on J-STAGE: September 22, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1183
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The general method of measuring the half-value layer (HVL) for X-ray computed tomography (CT) using square aluminum-sheet filters is inconvenient in that the X-ray tube has to be set to stationary mode. To avoid this inconvenience, we investigated a new method using copper-pipe filters that cover the ionization chamber (copper-pipe method). Using this method, the HVL can be measured at the isocenter in the rotation modes of CT. We examined the accuracy and reproducibility of the copper-pipe method compared with those of the general method. The effective energy measured using the copper-pipe method correlated well with the general method (y=1.064x, r=0.987), and its error was 1.81±1.38%. The results indicate that the copper-pipe method enables accurate measurement of the effective energy of X-ray CT and is a convenient method suited to all general X-ray equipment as well as all X-ray CT.
    View full abstract
    Download PDF (1699K)
Notes
  • Basic Examination of Uniformity of Image and Contrast of Multi-transmit System
    Shuhei Shibukawa, Tomohiko Horie, Hiroaki Nishio, Isao Muro
    2011 Volume 67 Issue 9 Pages 1192-1199
    Published: September 20, 2011
    Released on J-STAGE: September 22, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1192
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    In 3.0-T magnetic resonance imaging (MRI), shortened radio frequency (RF) wavelengths cause B1 inhomogeneity. Multi transmit (MT) has been reported as a method of solving this problem. We compared MT with single transmit (ST) and ST body-tuned CLEAR (BTC) in terms of basic performance because we got an opportunity to use MT. A phantom was used to evaluate the uniformity of the flip angles (FAs) of images, the phantom’s diameter, and the specific electric conductivity. To evaluate contrast, volunteers performed the significant difference test, and the changes in the FA of the phantom were measured. MT and BTC were better than ST in terms of the uniformity of the images. MT had the best contrast. The results showed that the uniformity of the images and the contrast were improved using MT compared with ST because MT can be uniformly irradiated to an object using two individual RF transmitters.
    View full abstract
    Download PDF (1751K)
  • Development of a Cone-beam CT System for Radiological Technologist Education
    Atsushi Teramoto, Kaho Ozaki, Mariko Miyashita, Tomoyuki Ohno, Masatos ...
    2011 Volume 67 Issue 9 Pages 1200-1208
    Published: September 20, 2011
    Released on J-STAGE: September 22, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1200
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    For radiological technologists, it is very important to understand the principle of computed tomography (CT) and CT artifacts derived from mechanical and electrical failure. In this study, a CT system for educating radiological technologists was developed. The system consisted of a cone-beam CT scanner and educational software. The cone-beam CT scanner has a simple structure, using a micro-focus X-ray tube and an indirect-conversion flat panel detector. For the educational software, we developed various educational functions of image reconstruction and reconstruction parameters as well as CT artifacts. In the experiments, the capabilities of the system were evaluated using an acrylic phantom. We verified that the system produced the expected results.
    View full abstract
    Download PDF (2481K)
Clinical Technology
  • The Construction of a Quality Assurance System for Images in General Radiography in a Filmless Environment: Construction of an Accurate and Swift Workflow
    Eiji Yamada, Kenji Kishimoto, Kenichi Kusumi, Toshihiko Kimura, Akihir ...
    2011 Volume 67 Issue 9 Pages 1209-1215
    Published: September 20, 2011
    Released on J-STAGE: September 22, 2011
    DOIhttps://doi.org/10.6009/jjrt.67.1209
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    When medical records went digital at our hospital, we also went filmless. In the general radiography department, we were forced to change the workflow, so we created a new one. We introduced a system of quality assurance for images between consoles and PACS. As our original improvement, we added to the system a function to automatically narrow down patient images and a function to automatically sort images. We divided quality assurance for images into 1st and 2nd quality assurance and defined and managed it. In addition, we measured the time for each process of the workflow with and without film use. We compared 10 cases of chest and abdomen radiographs with 10 cases of bone radiographs. As a result, by using this system of quality assurance for images, we were able to cut three minutes from each examination, leading to quicker work.
    View full abstract
    Download PDF (2158K)
The 67th Annual Scientific Congress
JIRA Topics
About JSRT (Japanese Society of Radiological Technology)
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top