Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
Search
Advanced search
OR
Browse
Search
Volume 68, Issue 8
Displaying 1-18 of 18 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
Opening Article
Originals
  • Comparison of the Probability of Meeting Up with Premature Contraction during Scanning in 320-area Detector Computed Tomography with That in 64-multidetector CT Coronary Angiography
    Tomonari Sano, Hideyuki Matsutani, Takeshi Kondo, Shinichiro Fujimoto, ...
    2012 Volume 68 Issue 8 Pages 951-960
    Published: August 20, 2012
    Released on J-STAGE: August 24, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.8.951
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Background: Because coronary computed tomography angiography (CCTA) by 320-area detector CT (320-ADCT) can be obtained in a short time, the probability of meeting up with premature contraction (PC) during scanning may be lower in 320-ADCT compared to 64-MDCT. The purpose is to compare the probability of meeting up with PC, scanning time, and image quality in patients with PC between the 2 groups (320-ADCT vs 64-MDCT). Methods: We have never rejected any CCTA examination due to arrhythmias. The 320-ADCT was performed in 2424 consecutive patients to include 70 atrial fibrillations (Afibs) and 64-MDCT in 1905 consecutive patients to include 51 Afibs. After exclusion of the patients with Afibs, we studied the probability of meeting up with PC during scanning and we compared the scanning time, image quality, and reconstruction phase for patients with PC between the 2 groups. Results: The probability of meeting up with PC during scanning in 320-ADCT (2.0%) is significantly lower (P<0.0001) than 64-MDCT (5.6%). For patients with PC, scanning time in 320-ADCT (2.9±0.6 s) was significantly shorter (P<0.0001) than 64-MDCT (9.5±1.9 s) and image quality in 320-ADCT (2.9±0.3 points) was significantly higher (P<0.0001) than 64-MDCT (2.2±0.8 points). CCTA was reconstructed in mid-diastolic phase in 93% of patients with PC using the 320-ADCT with arrhythmia rejection system. Conclusion: The scanning time of 320-ADCT was 1/3 in comparison with that of 64-MDCT, and the probability of meeting up with PC during scanning in 320-ADCT was 1/3 in comparison with that in 64-MDCT.
    View full abstract
    Download PDF (2605K)
  • Physical Image Properties of Digital Radiography Systems in Low Dose Range
    Hiroshi Kunitomo, Katsuhiro Ichikawa, Ryo Higashide, Kazuya Ohashi
    2012 Volume 68 Issue 8 Pages 961-969
    Published: August 20, 2012
    Released on J-STAGE: August 24, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.8.961
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    We measured physical image properties of a flat panel detector (FPD) system and a computed radiography (CR) system, targeting to a low dose range (reference dose: 2.58×10-7 C/kg: to 1/20 dose). Input-output properties, pre-sampled modulation transfer functions (pre-sampled MTFs), and normalized noise power spectra for an FPD system equipped with a CsI scintillator (FPDcsi) and a CR system with an imaging plate coated with storage phosphor (CR) were measured at the low dose range for radiation quality of RQA3 (≈50 skV) and RQA5 (≈70 kV), and detective quantum efficiencies (DQEs) were calculated. In addition, in order to validate the DQE results, component fractions of Poisson and multiplicative and additive noise were analyzed using relative standard deviation analysis. The DQE values of FPDcsi were decreased with dose decrease, and contrarily to these, those of CR were increased. At the 1/10 and 1/20 doses for RQA3, the DQEs of FPDcsi and CR became almost the same. From the results of RSD analysis, it was proved that the main cause of DQE deterioration on FPDcsi are non-negligible additive (electronic) noise, and the DQE improvement on CR was caused by both of significant multiplicative (structure) noise and very low electronic noise. The DQE results were validated by comparing burger phantom images of each dose and radiation quality.
    View full abstract
    Download PDF (1492K)
Notes
  • Reduction of Radiation Exposure and Image Quality Using Dose Reduction Tool on Computed Tomography Fluoroscopy
    Daisuke Sakabe, Yoshinori Funama, Hiroo Murazaki, Syuichi Tochihara, M ...
    2012 Volume 68 Issue 8 Pages 970-978
    Published: August 20, 2012
    Released on J-STAGE: August 24, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.8.970
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The purpose of our study was to measure the reduction rate of radiation dose and variability of image noise using the angular beam modulation (ABM) on computed tomography (CT) fluoroscopy. The Alderson-Rando phantom and the homemade phantom were used in our study. These phantoms were scanned at on-center and off-center positions at -12 cm along y-axis with and without ABM technique. Regarding the technique, the x-ray tube is turned off in a 100-degree angle sector at the center of 12 o’clock, 10 o’clock, and 2 o’clock positions during CT fluoroscopy. CT fluoroscopic images were obtained with tube voltages, 120 kV; tube current-time product per reconstructed image, 30 mAs; rotation time, 0.5 s/rot; slice thickness, 4.8 mm; and reconstruction kernel B30s in each scanning. After CT scanning, radiation exposure and image noise were measured and the image artifacts were evaluated with and without the technique. The reduction rate for radiation exposure was 75–80% with and without the technique at on-center position regardless of each angle position. In the case of the off-center position at -12 cm, the reduction rate was 50% with and without the technique. In contrast, image noise remained constant with and without the technique. Visual inspection for image artifacts almost have the same scores with and without the technique and no statistical significance was found in both techniques (p>0.05). ABM is an appropriate tool for reducing radiation exposure and maintaining image-noise and artifacts during CT fluoroscopy.
    View full abstract
    Download PDF (2473K)
  • Different Educational Programs on Medical Ultrasound Examination for Radiological Technologists and Medical Technologists
    Kazunori Ganjitsuda, Masami Tagawa, Kenichi Ikeda, Masahiro Fukushi, J ...
    2012 Volume 68 Issue 8 Pages 979-985
    Published: August 20, 2012
    Released on J-STAGE: August 24, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.8.979
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Radiological technologists (RTs) and medical technologists (MTs) are legally allowed to work as sonographers performing medical ultrasound examination. Despite the total number, much fewer RTs work as sonographers than MTs. To explore the reason, we investigated educational programs, universities, and colleges for both specialties. First, we established five categories of sonographers’ competency: 1) Anatomy for imaging diagnosis, 2) Diseases and diagnosis, 3) Imaging, 4) Structure and principle of the equipment, and 5) Evaluation of image quality, using competence reported by the International Society of Radiographers and Radiological Technologists (ISRRT) and diagnostic competency required of sonographers in Japan. Using these categories, we analyzed the content and total instruction time by lectures and seminars based on information written in the syllabi, and explored the differences in education related to sonographers’ competency in both programs. “Anatomy for imaging diagnosis” was taught in 15 RT programs (93.8%), and 6 MT programs (31.6%). “Diseases and diagnosis” was taught in 13 RT programs (86.7%), and 8 MT programs (53.3%). “Imaging” was taught in 14 RT programs (100%), and 13 MT programs (76.5%). “Structure and principle of the equipment” was taught in 12 RT programs (85.7%), and 6 MT programs (31.6%). “Evaluation of image quality” was taught in 11 RT programs (84.6%), and 3 MT programs (15.0%). The average instruction time for RT was longer than for MT programs in all categories. RTs are educated and have a foundation to be sonographers at graduation, and may have the possibility to expand their career in this field.
    View full abstract
    Download PDF (676K)
Clinical Technologies
  • Influence on Measurements of Pre-irradiation Due to Differences in Ionization Chamber Shape or Frequency in Use
    Tetsunori Shimono, Hidekazu Nambu, Kosuke Matsubara, Kichiro Koshida, ...
    2012 Volume 68 Issue 8 Pages 986-996
    Published: August 20, 2012
    Released on J-STAGE: August 24, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.8.986
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Ionization chamber measurements in radiation therapy should be repeatedly performed until a stable reading is obtained. Ionization chambers exhibit a response which depends on time elapsed since the previous irradiation. In this study, we investigated the response of a set of two Farmer-style, one Plane parallel, and seven small ionization chambers, which are exposed to 4, 6, 10, and 14 MV. The results show that Farmer-style and Plane parallel ionization chambers settle quickly within 9–20 min. On the other hand, small ionization chambers exhibit settling times of 12–33 min for 6, 10, and 14 MV. It will take longer for a settling time of 4 MV. The settling time showed time dependent irradiation. The first reading was up to 0.76% lower in the Farmer-style and Plane parallel ionization chambers. The small ionization chambers had a 2.60% lower first reading and more gradual response in reaching a stable reading. In this study, individual ionization chambers can vary significantly in their settling behavior. Variation of the responses on ionization chambers were confirmed not only when radiation was not used for a week but also when it was halted for a month. Pre-irradiation of small ionization chambers is clearly warranted for eliminating inadvertent error in the calibration of radiation beams.
    View full abstract
    Download PDF (2684K)
  • The Examination of Attenuation Correction Using One Computed Tomography Scan in Myocardial Perfusion Stress-rest Single Photon Emission Computed Tomography
    Makoto Sasaki, Shigeto Kawase, Yoshihiro Miyazaki, Takahiro Fujimoto, ...
    2012 Volume 68 Issue 8 Pages 997-1005
    Published: August 20, 2012
    Released on J-STAGE: August 24, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.8.997
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Attenuation correction (AC) of myocardial perfusion stress-rest single photon emission computed tomography (SPECT) with hybrid SPECT/computed tomography (CT) is effective. But because CT scan is done two times, the radiation exposure of patients increases. Therefore, we suggested a new method of AC that can correct attenuation of SPECT images acquired during a rest examination by using the CT scan during a stress examination. AC was done using one CT scan and we evaluated the clinical appropriateness of using this method. Matters of this study were (1) positional reproducibility of data analysis machine (Xeleris) (2) phantom study: accuracy of registration by manual and repetition reproducibility (3) clinical study using 99mTc-tetrofosmin. Comparison methods were analyzed by calculating the difference perfusion (Dp) with 17-segments model of American Heart Association and visual evaluation of three axis images in the myocardium. In the phantom study, because most of the score of 17-segments accord (Dp≤1), it was considered that the shift on SPECT/CT’s bed was reproduced by the shift on Xeleris. And it is shown that AC with CT scan on deference point was accuracy. In the clinical study, there were a few differences in Dp (Dp≤4) and approximately equal evaluation on visual evaluation was provided, which compared with conventional methods. Because AC of myocardial perfusion stress-rest SPECT by one CT scan showed that it was approximately equal in evaluation compared with conventional methods, we expect to be able to use this method in clinical cases.
    View full abstract
    Download PDF (2288K)
  • Evaluation of Low Dose Chest Expiratory High Resolution Computed Tomography for Diagnosis of Air Trapping
    Tomokazu Shohji, Sousuke Higuchi, Tetsuya Iida, Tetsuya Watanabe, Hiro ...
    2012 Volume 68 Issue 8 Pages 1006-1014
    Published: August 20, 2012
    Released on J-STAGE: August 24, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.8.1006
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    In our hospital, expiratory high resolution computed tomography (HRCT) is being performed in patients with chronic obstructive pulmonary disease (COPD). Because expiratory HRCT is used in combination with inspiratory HRCT, it can provide less exposure according to diagnostic purposes. In the present study, we tried low-dose expiratory HRCT in terms of visual assessment and analysis software of phantom experiments. As a result, visual assessment in the dose reduction rate was about 50% to 75% against conventional exposure doses. Thoracic examinations are common in organs with high tissue weighting factors, and the present study shows a very effective means for medical exposure reduction.
    View full abstract
    Download PDF (2294K)
  • The Protocol of Dose Reduction in Liver Perfusion Computed Tomography
    Tomoya Nakano, Toshiya Nasada, Wataru Joumoto, Takuya Enoki, Yasukazu ...
    2012 Volume 68 Issue 8 Pages 1015-1024
    Published: August 20, 2012
    Released on J-STAGE: August 24, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.8.1015
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Cerebral perfusion computed tomography (CT) has been widespread, but abdominal perfusion CT has not been very popular because there has been a problem with regard to the limit of irradiation range and respiratory effects. Recently, it became easy to perform perfusion of abdominal organs because the use of multi detector row CT (MDCT) has been extensive. Along with it, the number of hospitals that perform liver perfusion CT has increased. However, patient dose of the liver perfusion CT is very high, making it very important to reduce patient dose. We created the virtual data that reduced the number of irradiation by partly reducing the data obtained on the liver perfusion CT. We compared the analysis results of all data with that of the partly reduced. It is possible to reduce the patient dose by reducing the number of irradiation because there was no significant difference in the analysis results.
    View full abstract
    Download PDF (2269K)
The 68th Annual Scientific Congress
Educational Lecture–Statistical Methods for Radiologic Research
Basic Lecture–Radiation Therapy Technology: Basic Strategy
Basic Lecture–From Diagnosis of the Breast to Treatment
Clinical Technology Course
Science Exchanges Committee Report
Science Exchanges Committee News
Students’ Page
JIRA Topics
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top