著者

荒木 不次男 守部 伸幸 下之坊 俊明 吉浦 隆雄 池上 徹 石戸谷 達世

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.60, no.7, pp.939-947, 2004

参考文献数

14

被引用文献数

3 1

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近年,リニアック装置を用いた頭部の定位放射線照射(stereotactic irradiation : STI,これにはSRSとSRTが含まれる),ガンマナイフ装置による定位手術的照射(stereotactic radiosurgery : SRS),サイバーナイフ装置による定位放射線治療(stereotactic radiotherapy :SRT)が急激な勢いで普及している(現在,サイバーナイフ装置は稼動停止状態である).さらに北米では,サイバーナイフの出現によりSRTは頭部のみならず体幹部にまで普及しはじめている.わが国においても一部の施設では,リニアック装置による動体追跡による高精度なSRTが試みられている.しかしながら,これらの定位放射線照射で用いられる極小照射野であるナロービームに問しては,十分に線量評価が確立されていないのが現状である.特に10mm以下の照射野に関しては,現在フィルムや半導体検出器などが利用されているが,フィルムでは濃度-線量変換の精度の問題,半導体検出器においてもエネルギー依存性や方向依存性などの問題があるため,より精度の高い検出器の開発が求められている.本研究班の目的は,初期の蛍光ガラス線量計に新かな技術的改良を加えて最近開発された蛍光ガラス線量計^<1,2)>を用いて,現在不可欠な放射線治療となってきているナロービームを用いた定位放射線照射の高精度な線量評価を確立することである.蛍光ガラス線量計は熱蛍光線量計(thermoluminescence dosimeter : TLD)に代わる新たな検出器として期待されているが,高エネルギー放射線治療領域の線量評価に対する報告はまだ少ない.本研究班報告書では,1)蛍光ガラス線量計の高線量モードにおける物理特性の評価,2)リニアック,サイバーナイフ,ガンマナイフ装置のナロービームの出力係数の評価について報告する.特に出力係数の評価については,現在一般的に使用されている他の検出器との比較から蛍光ガラス線量計の有用性について明らかにする.

著者

出路 静彦 有賀 英司 森 一幸 廣田 昌大 佐瀬 卓也 伊藤 茂樹 西澤 邦秀

出版者

公益社団法人日本放射線技術学会

雑誌

日本放射線技術學會雜誌 (ISSN:03694305)

巻号頁・発行日

vol.62, no.9, 2006-09-20

著者

坂本 肇 中村 修 弓削 誠 佐野 芳知 秋山 三郎 荒木 力

出版者

公益社団法人日本放射線技術学会

雑誌

日本放射線技術學會雜誌 (ISSN:03694305)

巻号頁・発行日

vol.56, no.10, pp.1256-1265, 2000-10-20

被引用文献数

26

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Total skin doses of patients resulting from interventional radiological procedures have the potential to exceed the threshold doses for deterministic effects such as erythema and epilation. It is desirable to measure entrance skin dose values non-invasively, easily, and at real time. If an acceptable mathematical equation could be established, the entrance skin dose could be calculated from the measured area exposure product. We established an equation to calculate the entrance skin dose from the measured area exposure product by creating calibration factors from phantom studies. In this report, entrance skin dose was calculated by using area exposure product and our established equation, and the calculated value was compared with that of the thermoluminescent dosimetric(TLD)value in a clinical setting. Although a significant correlation was found between the calculated and measured entrance doses, the deviation was about 10% in phantom studies and 20% in the clinical setting. Using our equation, calculation of ectrance skin dose is possible from area exposure product and is useful for patient dose control in the clinical setting.

著者

樋口 範雄

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.64, no.5, pp.655-657, 2008 (Released:2008-05-29)

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抄録はありません.

著者

林 裕晃 西原 貞光 小沼 洋治

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.5, pp.545-553, 2012-05-20 (Released:2012-05-30)

参考文献数

6

被引用文献数

1

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Due to accidents of the nuclear power plants in Fukushima prefecture, a lot of radioisotopes were diffused into the environment. They adhered onto the surface of the X-ray detector (imaging plate; IP) and many black spots were seen on the medical images. The process to count them is important to evaluate the degree of contamination and/or removal. In this study, we aimed to develop a counting method for black spots. Based on the analysis of the medical images having black spots, we summarized that areas affected by the certain black spots were limited to the eight pixels surrounding the most intensive pixel. The newly developed counting method was applied to these nine pixels (3×3 pixels) and selection rules were based on the following two information: 1. differences between the digital value of the most intensive pixel and those of the surrounding eight pixels, and 2. total summation of the digital values in the nine pixels. The estimated image based on our method showed a good concordance with the original image. Therefore, we summarized that our counting method is a powerful tool for estimating numbers of black spots.

著者

小笠原 克彦

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.7, pp.791-795, 2007-07-20 (Released:2007-10-04)

参考文献数

13

被引用文献数

4 1 1

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(抄録はありません)

著者

輪嶋 隆博

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.64, no.11, pp.1404-1409, 2008-11-20 (Released:2008-12-06)

参考文献数

15

著者

毛利 快晴 永井 義衛 佐藤 安男

出版者

公益社団法人日本放射線技術学会

雑誌

日本放射線技術學會雜誌 (ISSN:03694305)

巻号頁・発行日

vol.32, no.6, pp.602-606, 1977-03-01

著者

大谷 昂 金本 雅行 尾崎 公美 谷内田 拓也 松田 祐貴 木戸屋 栄次

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

pp.2023-1380, (Released:2023-06-19)

参考文献数

23

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【目的】肝臓のmagnetic resonance imaging(MRI)検査において,全肝の呼吸同期併用拡散強調画像(respiratory-triggered-diffusion-weighted imaging: R-DWI)は磁場不均一の影響により肝臓頭側の横隔膜ドーム下の画質低下が問題となる.そこでドーム下に範囲を絞った呼吸停止下DWI(breath-hold-DWI: B-DWI)の追加撮像の有用性を検討した.【方法】3.0 TのMR装置を使用し,2022年7月から8月に当院でethoxybenzyl(EOB)-MRI検査を受けた22例(男性14名,女性8名,平均年齢69.0±11.7歳)を対象とした.R-DWIとB-DWIのドーム下の視認性について放射線科医1名と放射線技師3名で4段階(1~4点)での視覚評価を行った.また,各DWIのapparent diffusion coefficient(ADC)値を比較した.【結果】R-DWIと比較してB-DWIではドーム下の視認性が向上した(2.67±0.71 vs. 3.25±0.43, p<0.05).各DWIのADC値に有意差はみられなかった(p>0.05).【結語】B-DWIはドーム下の視認性に優れ,R-DWIを補完する役割が期待できるため,EOB-MRI検査において追加撮像する有用性は高い.

著者

船間 芳憲

出版者

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.11, pp.1461-1467, 2011-11-20

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低線量で増加する画像ノイズ、X線量低減の有効策である低管電圧CTと逐次近似画像再構成法について概説する。

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 10

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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

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

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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

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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

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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

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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

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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

三枝 紀雄

出版者

公益社団法人日本放射線技術学会

雑誌

日本放射線技術學會雜誌 (ISSN:03694305)

巻号頁・発行日

vol.51, no.9, 1995-09-01

著者

村中 良之 宮下 正己 新地 啓治 柴田 雅道 野村 耕治 笠原 茂 岡田 時治

出版者

公益社団法人日本放射線技術学会

雑誌

日本放射線技術學會雜誌 (ISSN:03694305)

巻号頁・発行日

vol.49, no.2, 1993-02-01

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マンマ厚, 目的組織によって適切な管電圧, グリッドの装着を選ぶ必要がある.

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

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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.