日本放射線技術学会雑誌
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
64 巻 , 1 号
選択された号の論文の16件中1~16を表示しています
巻頭言
新春座談会
原著
  • 谷 正司, 田辺 智晴, 阿部 修司, 三原 一博
    2008 年 64 巻 1 号 p. 15-24
    発行日: 2008/01/20
    公開日: 2008/03/01
    ジャーナル フリー
    We devised an application that uses the “Maximum value reading method (AutoIV)” for bedside chest radiography in a neonatal intensive care unit (NICU) that used the Fuji Computed Radiography (FCR) System. The application, named AutoIV-N, uses the relationship for density correction between radiographic conditions (mAs) and the Display Parameter (GS). GS=f (mAs) can be considered the relationship that connects FCR and the X-ray generator. When AutoIV-N is used, radiographic image contrast does not change. Further, radiographic image density fluctuation can be eliminated by random elements such as X-ray output fluctuation of the X-ray generator and the decline of photo-stimulated luminescence caused by fading of the imaging plate. Accordingly, image recording that is suitable for follow-up chest radiography is made possible. We choose nine patients and performed a comparison of radiographic density fluctuation in AutoIV-N and Fix. AutoIV-N was found to be more stable than Fix. It is possible to use the radiographic imaging condition that is optimized for all patients in the NICU by AutoIV-N. This facilitates radiation exposure optimization in medicine.
  • 丸山 敏則, 山本 秀樹
    2008 年 64 巻 1 号 p. 25-34
    発行日: 2008/01/20
    公開日: 2008/03/01
    ジャーナル フリー
    A good positioning technique is of great importance in radiology in order to obtain accurate diagnostic information and reduce the patient’s X-ray exposure. In positioning training, students place the phantom on the table under an X-ray tube, adjust the position of the phantom, and repeat the positioning practices until they can obtain fine diagnostic images. As X-ray films are usually used in radiography, the development of such films is necessary. In this kind of training practice, it takes a great deal of time to obtain the X-ray image at the phantom position. It is desirable for students to perform positioning accurately and to confirm the results of positioning within a short time. In this article, we propose a new positioning training method using digital image processing. First, we scan the skull phantom by CT (computed tomography) and obtain CT images. Next, we measure the positioning information of the phantom under the X-ray equipment by using scene analysis. Then, we develop a method that produces the plane image corresponding to the detected phantom position under the X-ray tube. It is expected that our method will be useful as a teaching device to help in the practice of the positioning techniques for various organs without X-ray exposure and, furthermore, in the development of X-ray films.
  • 高倉 亨, 松原 佳菜, 溝脇 尚志, 中田 学, 矢野 慎輔, 岡田 孝, 藤本 隆広, 加茂前 健, 田中 利恵, 越田 吉郎, 菊池 ...
    2008 年 64 巻 1 号 p. 35-40
    発行日: 2008/01/20
    公開日: 2008/03/01
    ジャーナル フリー
    Background and Purpose: We verified the propriety of our systematic error reduction strategy by means of a computer simulation based on our data of position error with a prone fixation device for prostate IMRT. Materials and Methods: Computer simulations of the off-line correction method for systematic setup errors based on the portal imaging taken on the first several days of the treatment session were performed. Using the computer simulations, an optimal number of portal images were evaluated for the SD value, from 0.5 mm to 1.5 mm at a 0.25 mm interval, and the respective required setup margins were calculated. Results: The value of systematic error was reduced as the frequency of data obtained increased. Moreover, the reduction rate was so remarkable that random error was large.
  • 坂井 真二, 片山 礼司, 杜下 淳次, 坂口 太郎, 大久保 征司, 前田 孝, 早渕 尚文
    2008 年 64 巻 1 号 p. 41-49
    発行日: 2008/01/20
    公開日: 2008/03/01
    ジャーナル フリー
    The purpose of this study was to evaluate the basic imaging properties of the two latest digital radiographic X-ray systems, namely, the DynaDirect Winscope 6000 (abbr. as System A, Toshiba Medical Systems) and the Sonialvision Safire Multi (abbr. as System B, Shimadzu Corp.). These systems were based on a direct-conversion flat panel detector (FPD) of amorphous selenium. The basic imaging properties of the two systems were evaluated by measuring characteristic curves, presampled modulation transfer functions (MTFs), and noise power spectra (NPS) using DICOM images to which no resampling was performed with a matrix size of 2048×2048. In addition, noise equivalent quanta (NEQ) and detective quantum efficiency (DQE) calculated from the result of the basic imaging properties were evaluated. The characteristic curves of the two systems showed quite high linearity. The MTFs of the two systems indicated high-resolution properties, as is well known to be an advantage of the direct conversion FPD system. However, the NPS of System A showed better performance than System B under the same exposures. Therefore, the DQE of System A was higher than that of System B at all spatial frequencies.
  • 原 孝則, 市川 勝弘, 丹羽 伸次
    2008 年 64 巻 1 号 p. 50-56
    発行日: 2008/01/20
    公開日: 2008/03/01
    ジャーナル フリー
    Analysis of the detailed physical property in CT system is important in an understanding of a clinical image. In this study, we evaluated resolution power property about the positions and direction for in-plane in CT system. The indexes of the resolving power property of CT images were measured by MTFs using the thin metal wire (diameter of 0.2 mm). We measured the positions of the iso-center and the off-center (32 mm, 64 mm, 96 mm, 128 mm) in in-plane. One-dimensional MTFs for the X-direction and Y-direction were calculated by the numerical slit scanning method. Then, MTF was calculated from the corresponding direction. As a result, when a filter kernel of high resolutions (B70) is used in the position of 128 mm, the resolution of X-direction was inferior to the Y-direction about 30% (at the MTF-value of 0.5 cycles/mm). Moreover, the resolution of X-direction at the position of 128 mm was inferior to the center about 33% (at the MTF-value of 0.5 cycles/mm). The resolving power property of in-plane in CT system was decreased in the calculation from the numerical slit that becomes perpendicular to the direction of centrifugal and, decreased proportionately with the distance from the center. Also, the resolutions along the centrifugal direction fell off remarkably at the peripheral area. And also, it turned out that the declining trend becomes larger, when the filter function for high-resolving power that is adapted for lungs is used.
ノート
  • 若林 康治, 諸澄 邦彦, 芝崎 匡樹, 松田 幸広
    2008 年 64 巻 1 号 p. 57-64
    発行日: 2008/01/20
    公開日: 2008/03/01
    ジャーナル フリー
    For ATP stress 99mTc-Tetrofosmin myocardial perfusion images (MPI), SPECT imaging is normally started 60 minutes after tracer injection. When the same procedure is applied to Adenosine (Ado) stress MPI, the frequency of the mask-out procedure after reconstruction (MOP) is increased. In this study, we examined the optimal imaging time from accumulation and distribution of isotope to neighboring organs. Time-count curves from dynamic and planer images of the heart, liver, and left upper abdomen were generated in 7 patients for optimal imaging time. MOP was evaluated in ATP stress MPI, in which imaging started 60 minutes after tracer injection (ATP 60), Ado stress MPI with imaging 60 minutes after injection (Ado 60), and Ado stress MPI with imaging 30 minutes after injection (Ado 30), in 575 patients. Up to 30 minutes after injection, washout from the liver was rapid, but after 30 minutes, it was slow. Washout from the left upper abdomen was not constant. MOP was 12.1% ATP 60, 23.1% Ado 60, and 13.2% Ado 30. Changing from Ado 60 to Ado 30 significantly decreased MOP (p<0.05). On adenosine stress MPI, it shortened examination time and enabled SPECT imaging to start 30 minutes after tracer injection.
臨床技術
  • 松原 孝祐, 越田 吉郎, 鈴木 正行, 西村 綾, 上野 博之, 高田 忠徳, 辻井 秀夫, 山本 友行
    2008 年 64 巻 1 号 p. 65-72
    発行日: 2008/01/20
    公開日: 2008/03/01
    ジャーナル フリー
    In this study, we evaluated clinical images to determine appropriate settings for slice thickness in screening examinations for hepatocellular carcinoma and metastatic liver cancer, which are frequently performed in abdominal CT. The clinical images of 15 cases screened for hepatocellular carcinoma and 15 cases screened for metastatic liver cancer were evaluated. The evaluation was visually performed by three abdominal radiologists, and the sensitivity and specificity of each slice thickness were calculated. Results: differences in sensitivity and specificity were not found between slice thicknesses of 2.5 mm and 5.0 mm; however, sensitivity and specificity were low, and confidence was also low at a 10.0 mm slice thickness. Furthermore, when a 5.0 mm slice thickness was adopted, it was shown that radiation dose in limited parts could be reduced greatly to a noise level that compared equally with a study in which a 2.5 mm slice thickness was adopted in another evaluation. Therefore, the objective could be achieved by using a slice thickness of about 5.0 mm in multidetector-row CT examinations for the screening of liver cancer, while controlling patient dose to a minimum.
教育講座―技師が書く技師のための読影講座―
臨床技術講座
連載読み物―医療の周りの法律について(7)―
学術交流委員会だより
JIRAトピックス
feedback
Top