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

竹内 友一 小倉 明夫 椎名 亮介 中野 裕喜

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.75, no.7, pp.631-637, 2019 (Released:2019-07-20)

参考文献数

16

被引用文献数

2 2

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Recently, many methods are suggested to evaluate spatial resolution in MRI. However, those techniques are not simple and easy. The International Electrotechnical Commission (IEC) recommends a method to evaluate spatial resolution using a periodic pattern image as IEC 62464-1. IEC 62464-1 prescribes specifications and placement of phantom, and a method of analysis, but these details grounds are not clear. A purpose of this study is to examine the effect in each factor of IEC 62464-1 method and define the characteristics of this method. Nine phantoms with different plate thickness were made including prescribed specifications of IEC 62464-1. Imaging was conducted with changing the placement angle of these phantoms. Also, analysis was carried out in region of interest (ROI) of three different size. As a result, the placement angle of the phantom, measurement error was <1% on a condition prescribed by a method of IEC 62464-1. There was not the effect if the transverse diameter for the longitudinal diameter exceeded 100% fort the size of ROI. In specifications of the phantom, there was not the dependence for the thickness of the plate of the phantom in IEC 62464-1 prescribes.

著者

小倉 明夫 Ogura Akio

出版者

金沢大学

雑誌

博士学位論文要旨 論文内容の要旨および論文審査結果の要旨/金沢大学大学院医薬保健学総合研究科(保健学専攻)

巻号頁・発行日

no.平成22年5月, pp.7, 2010-05-01

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取得学位 : 博士(保健学), 学位授与番号 : 医博甲第2101号 , 学位授与年月日 : 平成22年3月23日, 学位授与大学 : 金沢大学, 審査結果の報告日 : 平成22年2月12日

著者

五月女 華 小倉 明夫 浅井 歩実 藤生 敦哉

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.9, pp.861-868, 2018

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<p>Capillaries are the most basic and important blood vessel of the circulatory systems. The evaluation of the blood flow may contribute to many studies in future. We evaluated the capillary blood flow change of lower limb muscle over time before and after the exercise used by magnetic resonance imaging-intravoxel incoherent motion (MRI-IVIM) obtained perfusion information. Furthermore, we examined an association between the muscle pain after the exercise and the diffusion weighted image (DWI) indexes. DWI was imaged using multi-b values for a thigh and calf muscles. MRI was performed just after an exercise test, 3, 6, and 24 hours later, and the IVIM index and diffusion index were calculated. Furthermore, we interviewed the degree of the muscle ache 24 hours later. As a result, pseudo diffusion coefficient (D*) and f value as IVIM index increased after-exercise as compared with pre-exercise and decreased in 3 hours later. A similar tendency was found in the apparent diffusion coefficient and the diffusion coefficient as diffusion index. Furthermore, all indexes increased in after exercise from before exercise and decreased with time passed and increased again 24 hours later. In conclusion, IVIM could obtain capillary blood flow information, and it was suggested to contribute for sports medicine in future.</p>

著者

本郷 隆治 小倉 明夫 井上 博志 林 浩二 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.57, no.5, pp.573-580, 2001-05-20 (Released:2017-06-30)

参考文献数

8

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In recent years, as gradient magnetic resonance imaging (MRI)systems have become larger and faster, the influence of low-frequency alternating magnetic fields on the human body during rapid scanning have become significant in terms of patient health. It has become more important to monitor time-variant magnetic fields (dB/dt). From this point of view, we measured the maximum dB/dt for clinical scanning using a self-made search coil and storage oscilloscope that conformed to international standard IEC 60601-2-33(1995). The results were almost the same as the calculated values. In this brief report, we introduce to clinical operators the method of measuring maximum dB/dt.

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

画像通信

巻号頁・発行日

vol.32, no.1, pp.23-26, 2009

著者

宮地 利明 安彦 茂 大久 敏弘 小倉 明夫 久保 均 滝澤 修 竹田 浩康 土橋 俊男 土井 司 中野 努

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.55, no.12, pp.1167-1179, 1999-12-20

被引用文献数

4

著者

小倉 明夫 東田 満治 山崎 勝 井上 博志

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.54, no.6, pp.778-783, 1998-06-20

被引用文献数

10

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To calculate the contrast-to-noise ratio (CNR) on magnetic resonance images, an equation selected to match each study is commonly used. The CNR values calculated using these equations may have their own characteristics. Therefore, the characteristics of four commonly calculated CNRs were evaluated in comparison with signal detectability. For the calculation of CNR, a phantom with five different solutions of CuSO_4 was imaged using various scan sequences with different TR and NEX. These images, which had different levels of noise and contrast, were measured for averaged signal intensity and standard deviation of noise in the same ROIs (regions of interest). To define signal detectability, Burger's phantom soaked in the CuSO_4 solution was imaged with the same pulse sequences used to evaluate CNR. Burger's phantom images were evaluated by five observers with a 50% confidence level. The characteristics of each CNR valuewere evaluated by correlating them with signal detectability. The results showed that some calculated CNRs indicated the noise element, but contrast element. From the point of view of signal detectability, the equation using the average of local variance and global variance with respect to coarse pixels was superior to others.

著者

山崎 勝 東田 満治 井上 博志 林 浩二 小倉 明夫 大竹野 浩史 本郷 隆治

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.53, no.1, 1997-01-20

被引用文献数

3

著者

小倉 明夫 前田 富美恵 宮井 明 本郷 隆治

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.60, no.11, pp.1543-1549, 2004-11-20

被引用文献数

14

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The contrast-to-noise ratio (CNR.) is often used to evaluate magnetic resonance images, because it has two components, contrast and SNR, and indicates the detectability of clinical lesions. Two methods (using a phantom and using clinical images) are employed to measure CNR. In addition, there are some methods of measurement that use clinical images. In this report, the accuracy of measurement and correlation for signal detectability were evaluated in four methods of measuring CNR using clinical images. The results indicated that the inter-tissue method using an air signal provided good accuracy and was consistent with signal detectability using observer performance. In addition, a small region of interest (ROI) was better suited as the target for CNR measurement using clinical images.