著者

松原 孝祐

出版者

公益社団法人 日本放射線技術学会

雑誌

放射線防護分科会会誌 (ISSN:13453246)

巻号頁・発行日

vol.38, pp.35-38, 2014-04-10 (Released:2017-12-29)

著者

小林 正尚 大塚 智子 鈴木 昇一

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.69, no.1, pp.19-27, 2013-01-20 (Released:2013-01-25)

参考文献数

18

被引用文献数

9 9

---

The purpose of this paper is to reappraise the accuracy of a conversion coefficient (k) reported by International Commission on Radiological Protection Publication 102 Table A.2. The effective doses of the routine head computed tomography (CT), the routine chest CT, the perfusion CT, and the coronary CT were evaluated using the conversion coefficient (adult head: 0.021 mSv·mGy-1·cm-1, adult chest: 0.014 mSv·mGy-1·cm-1). The dose length product (DLP) used the value displayed on the console on each scanning condition. The effective doses were evaluated using a human body type phantom (Alderson Rando phantom) and thermoluminescent dosimeter (TLD) elements for comparison with the converted value. This paper reported that the effective doses evaluated from conversion coefficient became different by 0.3 mSv (17%) compared with measurements, the effective dose computed with the conversion coefficient of the adult chest may be underestimated by 45%, and the bolus-tracking which scans the narrow beams should not use a conversion coefficient.

著者

小倉 明夫

出版者

公益社団法人 日本放射線技術学会

雑誌

放射線撮影分科会誌 (ISSN:1345322X)

巻号頁・発行日

vol.32, pp.35-37, 1999-04-05 (Released:2017-12-28)

著者

鍋倉 良三 増田 和浩 高野 修彰 萩原 充人 木村 幹郎 天内 廣 佐藤 次男 中澤 靖夫 小美濃 直人 長谷川 光男 若松 修

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.51, no.2, pp.158-166, 1995-02-01 (Released:2017-06-29)

参考文献数

7

被引用文献数

1 1

著者

寺本 大翼 潮田 悠一 佐々木 絢加 櫻井 佑樹 長濱 宏史 中村 麻名美 杉森 博行 坂田 元道

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.69, no.10, pp.1146-1152, 2013-10-20 (Released:2013-10-21)

参考文献数

13

被引用文献数

1

---

Various custom-made phantoms designed to optimize magnetic resonance imaging (MRI) sequences have been created and subsequently reported in JSRT. However, custom-made phantoms that correctly match the T1-value and T2-values of human brain tissue (gray matter and white matter) cannot be made easily or quickly. The aim of this project was to search for alternative materials, such as fruits and vegetables, for optimizing MRI sequences. The following eight fruits and vegetables were investigated: apple, tomato, melon, apple mango (Mangifera indica), banana, avocado, peach, and eggplant. Their potential was studied for use in modeling phantoms of normal human brain tissues. MRI (T1- and T2-weighted sequences) was performed on the human brain and the fruits and vegetables using various concentrations of contrast medium (gadolinium) in the same size tubes as the custom-made phantom. The authors compared the signal intensity (SI) in human brain tissue (gray matter and white matter) with that of the fruits and the custom-made phantom. The T1 and T2 values were measured for banana tissue and compared with those for human brain tissue in the literature. Our results indicated that banana tissue is similar to human brain tissue (both gray matter and white matter). Banana tissue can thus be employed as an alternative phantom for the human brain for the purpose of MRI.

著者

室 伊三男 神谷 陽 本田 真俊 堀江 朋彦

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.63, no.1, pp.91-96, 2007-01-20 (Released:2007-02-27)

参考文献数

7

被引用文献数

6 12

---

Echo planar imaging (EPI) is highly sensitive to static magnetic field inhomogeneities. The degree of local image compression and stretching is a function of the static field gradient in the phase-encoding direction. This is caused by the accumulation of a phase shift. Any static field shift will lead to a position shift in the image, and it is the regions with large static fields that are the most difficult to correct. We reduce image distortion by SENSE with an array coil. However, we often use a surface coil because we cannot use an array coil in clinical studies. In this case, image distortion becomes greater, and reduction of distortion is very important. For the purpose of this study, we examined the relation between imaging parameters and image distortion. Image distortion of EPI is unrelated to the following parameters: number of phase encodings, half scan, echo time, and diffusion b-value. However, the following parameters influenced image distortion: FOV, number of frequency encodings, rectangle FOV, and multi-shot imaging. Image distortion of EPI is decided by the area of the phase-encoding gradient and the interval of readout gradients. We hope that many institutions will find these data useful.

著者

白石 順二 宇都宮 あかね

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.53, no.6, pp.691-698, 1997-06-20 (Released:2017-06-29)

参考文献数

6

被引用文献数

15 11

---

Several methods of testing statistically significant differences were used to evaluate the usefulness of one diagnostic imaging system compared with any other imaging system using ROC analysis. Comparison of usefulness between conventional methods such as the two-tailed paired t-test and 95% confidence intervals, and Jackknife method for ROC analysis, which was reported a few years ago, were investigated with actual two experimental results from ROC studies. From the testing results, it was considered that conventional methods reguire large numbers of readers in order to improve the reliability of statistically significant test differenxes between the two imaging systems. When determining differences between two kinds of imaging modalities, the use of the Jackknife method was better than conventional methods in terms of the reliability of test results, because conventional methods do not consider variances between readers and case samples.

著者

出雲 雅樹 金子 毅義 小酒 広之 佐藤 剛 谷藤 大樹 中村 敦

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.58, no.12, pp.1639-1643, 2002

参考文献数

6

被引用文献数

3 1

---

When processing head MRA images, threshold values are automatically established using the MIP method, resulting in a high degree of reproducibility. As a result, two different individuals can produce highly comparable images. In addition, the MIP method is reportedly effective for depicting fine vessels. However, since information other than maximum values is ignored by the MIP method, data contained in original MRA images are not optimally utilized. The results confirmed that much of the information contained in original MRA images could not be seen on MIP processed images. In many cases, low-threshold processing was useful for depicting fine vessels and arterioles that could not be seen on MIP-processed images.

著者

西原 貞光 林 裕晃

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.67, no.8, pp.912-915, 2011-08-22 (Released:2011-08-24)

参考文献数

6

被引用文献数

5 1 5

---

Several hospitals have been observing black spots in medical images, and the radioisotopes (RIs) that cause the spots needs to be removed from the X-ray receptors. Our purpose is to show a flowchart for finding out under which conditions an imaging plate (IP) and other parts (for example, the cassette) are contaminated by RIs and to propose an effective method to remove them. The procedure follows. (1) Is RI activity low? (2) Are the surfaces of other parts contaminated? (3) Is the surface of the IP contaminated? (4) Are the insides of the other parts contaminated? To remove the adhered RIs, we applied a wipe test method using a wet type of chemical wiper. A certain hospital that observed black spots experimented with this method. As a result, the contaminated condition of the X-ray receptor was identified. In addition, we were able to remove the RIs from the IP. Therefore, our procedure is very effective for decontaminating adhered RIs from receptors.

著者

西村 恭昌

出版者

公益社団法人 日本放射線技術学会

雑誌

放射線治療分科会誌 (ISSN:13453211)

巻号頁・発行日

vol.27, no.1, pp.15-18, 2013 (Released:2017-12-29)

著者

中村 忍 川田 秀道 黒木 英郁 溝口 明日実

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.71, no.11, pp.1096-1102, 2015 (Released:2015-11-20)

参考文献数

21

被引用文献数

2

---

We evaluated the effect of orthopedic-metal artifact reduction (O-MAR) for metal artifact in computed tomography with 73 simulated seeds for brachytherapy in different sizes of display field of view (DFOV) obtained by helical scan under the same clinical scan condition. The metal artifacts were analyzed with the Gumbel's method by changing DFOV sizes 80 mm, 160 mm, and 320 mm. Gumbel distribution, scale parameter (γ), and location parameter (β) of the metal artifacts with O-MARwere compared with that of the metal artifacts with filtered back projection (FBP). In conclusion, it was considered that the effect of metal artifact reduction with O-MARwas influenced by DFOV size in this study. The reduction rates of scale parameter (γ) were 22.3%, 21.3%, and 10.0% in DFOV 80 mm, 160 mm, and 320 mm, respectively. The reduction rates of location parameter (β) were 27.4%, 23.4 %, and 9.8%. Therefore, the effect of metal artifact reduction with O-MARshowed the tendency of increasing with decreasing DFOV size.

著者

安井 修己 他名

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.53, no.5, pp.649, 1997-05-20 (Released:2017-06-29)

著者

山本 容江 今田 直幸

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.46, no.8, pp.997, 1990-08-01 (Released:2017-06-29)

著者

高津 安男 山村 憲一郎 宮地 利明 木村 哲哉 上山 毅 石黒 秋弘

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.68, no.10, pp.1346-1353, 2012-10-20 (Released:2012-10-22)

参考文献数

8

---

It is difficult for Rheumatoid Arthritis (RA) patients to remain in a strenuous position for a long time during examinations. The field of view (FOV): 250 mm is needed for hand examinations from the wrist to the finger. Two channel phased array coils are effective to use when examinations of the ‘off center’ are taken for the upper and lower extremities. The area of the array coils’ sensitivity can be expanded by shifting both coil elements 40–60% in the opposite direction of the element’s diameter. This method is given credibility due to the increased signal-to-noise ratio (SNR) in the peripheral regions (shifted directions), but loses value in the central area, as indicated by the decrease in SNR. This was confirmed in the image of the hand using visual assessment including the fat suppression technique. It was verified that the sensitivity area was expanded using Scheffe’s method of paired comparison (Ura’s modified method). An application at the other regions of the body can be expected to be used in the case of using parallel positioned coils during clinical situation.

著者

高橋 信次 細江 謙三 奥村 彦太郎 松浦 浩

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.13, no.1, pp.66, 1957-09-15 (Released:2017-06-21)

著者

松田 博史

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.62, no.8, pp.1066-1072, 2006 (Released:2007-02-23)

参考文献数

24

被引用文献数

8 6

著者

寺澤 操

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.56, no.5, pp.705-711, 2000-05-20 (Released:2017-06-30)

参考文献数

21

被引用文献数

1 1

著者

本田 道隆

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.66, no.5, pp.557-565, 2009-11-25 (Released:2010-07-09)

参考文献数

7

被引用文献数

2 1

著者

小林 明日香 渋川 周平 高野 晋 室 伊三男

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.74, no.10, pp.1180-1185, 2018 (Released:2018-10-20)

参考文献数

12

---

We have found that the number of packages influences contrast for brain tissue signals on fluid-attenuated inversion recovery (FLAIR). The purpose of this study was to evaluate the contrast of white and gray matters by changing the number of packages. In a volunteer study (n=8), FLAIR images were obtained with the various number of packages (number of package=2, 3, 4, 5). We investigated the same imaging condition at both 1.5 and 3.0T. The signal intensity of white and gray matters in all volunteers was increased as increasing the number of packages. Moreover, the contrast ratio between white and gray matters was slightly decreased. In our conclusion, the contrast between the gray and white matters on FLAIR was influenced by the number of packages.

著者

根本 整 永坂 竜男 大田 英揮 山下 裕市 二科 孝志 町田 好男

出版者

公益社団法人 日本放射線技術学会

雑誌

日本放射線技術学会雑誌 (ISSN:03694305)

巻号頁・発行日

vol.74, no.7, pp.675-684, 2018 (Released:2018-07-20)

参考文献数

21

---

With shortening of the gantry of magnetic resonance imaging (MRI) systems, large field-of-view (FOV) imaging has become difficult because static magnetic field nonuniformity and gradient magnetic field nonlinearity exacerbate geometric distortion of MR images. However, results of earlier studies have demonstrated that view angle tilting (VAT) can reduce severe image distortion attributable to local susceptibility effects of metals. Although VAT is usually applied to local magnetic field nonuniformity, in principle VAT is expected to correct distortion also for peripheral images in large-FOV MRI. Results from this phantom experiment using VAT with large-FOV verified the effectiveness of distortion correction. The experiment using VAT showed reduction of maximum distortion from 23.6 to −1.9 mm. Furthermore, results of a volunteer study confirmed the distortion correction capability of VAT: it reduced distortion and improved visibility of the anatomical structure. In conclusion, experimentally obtained results underscore VAT effectiveness for improving distortion in large-FOV MRI.