著者

佐保 辰典 大西 英雄

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.71, no.12, pp.1157-1164, 2015 (Released:2015-12-20)

参考文献数

31

被引用文献数

1 2

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Purpose: Detailed strategy for regional hemodynamics is significant for knowledge of plaque development on vascular diseases such as atherosclerosis. The aim of this study was to derive relation between atherosclerosis and hemodynamics at human carotid bifurcation by the use of computational fluid dynamics (CFD), and to provide more accurate hemodynamic information. Methods: Blood velocity datasets at common carotid artery were obtained by phase-contrast cine magnetic resonance imaging (PC cine MRI). Carotid bifurcation model was computed for systolic, mid-diastolic, and end-diastolic phase. Comparison of wall shear stress (WSS) was performed for each cardiac phase. Results: PC cine MRI provided velocity measurement for common carotid artery with various cardiac phases. The blood velocity had acute variation from 0.21 m/s to 1.07 m/s at systolic phase. The variation of WSS during cardiac phase was presented at carotid bifurcation model. High shear stress area was observed at dividing wall for all cardiac phases. The systole-diastole WSS ratio was 10.15 at internal carotid side of bifurcation. And low shear stress (<0.5 Pa) was observed at internal carotid side of bifurcation. Conclusion: Bifurcation area represented low shear stress and changed significantly WSS. The specific area with significant change in shear stress and low shear stress had good agreement with predilection sites of atherosclerosis. The result suggested that hemodynamics was related to atherosclerosis, and CFD analysis with various cardiac phases that were provided by PC cine MRI was allowed to determine an accurate analysis condition. This led to the representation of hemodynamics in vivo.

著者

金沢 勉 岩崎 友也 高橋 麻由 柿沼 健一 江塚 勇 山田 治行

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.59, no.8, pp.958-964, 2003-08-20 (Released:2017-06-30)

参考文献数

9

被引用文献数

2 3

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Although abducens nerve palsy is a relatively common disease, the abducens nerve has been almost impossible to identify, because it is one of the finest cranial nerves and runs three-dimensionally in the prepontine cistern. Three-dimensional constructive interference in steady state (3D-CISS) is helpful in visualizing fine structural elements in the central nervous system because of its higher spatial resolution and fewer artifacts from cerebrospinal fluid. In this study, we successfully visualized the abducens nerve using 3D-CISS. The procedures were as follows : first, Dorello's canal and the ponto-medullary sulcus were identified as visible, landmarks, and then the abducens nerve was followed to the root exit zone ; second, the gray scale of the original image was inverted to clearly visualize the cisternal course of the nerve and the neighboring small vessels ; and, finally, the entire cisternal course of the nerve was visualized in the same images in both oblique axial and oblique sagittal planes by a multi-planar reconstruction method. This reliable technique can be performed for the diagnosis of abducens nerve palsy.

著者

高木 祐一 橋田 昌弘 小味 昌憲 羽手村 昌宏

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.77, no.10, pp.1186-1195, 2021 (Released:2021-10-20)

参考文献数

16

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When the fat-suppression technique was used in the MRI examinations of neck and extremities, incomplete regions of fat suppression were depicted frequently. These incomplete regions were caused by the non-uniform static magnetic field (B0). On the other hand, a non-uniform B0 caused banding artifacts using a balanced steady-state free precession (bSSFP) sequence. We investigated the prediction of incomplete regions of fat suppression using the banding artifacts of the bSSFP sequence. The fat-suppression techniques used in this study were the chemical shift selective and spectral adiabatic inversion recovery methods for turbo spin echo imaging. Using an oil bottle attached to a staple, the scan parameters of the bSSFP sequence were adjusted to overlap with the banding artifacts in the incomplete regions of fat suppression. The neck, ankle joint and femur of healthy volunteers were scanned using the obtained scan parameters, and a visual assessment was performed. As a result, the incomplete region of fat suppression matched the region of the banding artifact. We were able to predict the incomplete region of fat suppression using the banding artifacts of the bSSFP sequence. If the optimized bSSFP sequence is used as the localizer, we can assess the situation of incomplete fat suppression before the main scanning and reduce rescanning due to incomplete fat suppression.

著者

赤沢 宏 山本 賢二

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.8, pp.947-952, 2001-08-20 (Released:2017-06-30)

参考文献数

5

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The fracture of the calcaneus frequently involves the surface of the posterior talocalcaneal joint. Therefore, the Anthonsen position, which is effective for visualizing the posterior talocalcaneal joint surface, should always be indicated in patients suspected of fracture of the calcaneus. The Anthonsen I position, however, requires x-ray irradiation at an angle of 25° in the head and caudal directions and at 30° in the dorsoventral direction, which frequently results in the need for repeated x-ray examinations due to orientation errors. An alternative approach is to conduct x-ray examination using a tilting table adjusted to an angle of 25° or to carry out x-ray examination at a position of 45° heel lift. The adoption of these techniques enables relatively unconstrained visualization of the talocalcaneal joint, although x-ray examination in the heel lifting position may cause stress to patients suffering post-traumatic pain. The reproducibility of post-traumatic, preoperative and postoperative projections, however, is poor. As a solution to these problems, we have developed a new x-ray examination technique. The incident x-ray angle has been simplified by synthesizing the two angles used with the Anthonsen I position. Furthermore, the position of the foot is determined by means of an auxiliary projection device. Our simplified version of the Anthonsen I position reduces the number of projection processes and does not require the patient to adopt an awkward position. In addition, this modified technique enables the visualization of the posterior talocalcaneal joint surface as clearly as with conventional x-ray examination.

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

小川 憲一

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.65, no.1, pp.50-56, 2009-01-20 (Released:2009-02-11)

参考文献数

2

被引用文献数

6 7

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With attention given to the fact that information on weight and height is available in advance from electronic medical charts, we devised a method for determining body thickness on the basis of a simple calculation. The formula is as follows: body thickness=weighta×heightb×f. In order to obtain body thickness from the above formula, it is necessary to determine optimal factors of a, b, and f. Therefore, the formula is modified to give f=body thickness/weighta×heightb. Then, a multiplier of a with b is changed to determine a combination in which f is varied to the smallest extent. Every site of the body is checked to find that an optimal multiplier of a with b is weight0.6×height–0.8. This multiplier is applicable to all sites of the body. Then, f is given as a median of 15 to 74 cases in which calculation is made for each case based on the formula of weight0.6×height–0.8 and the body thickness. A difference between calculation values and measured values is equivalent to the variation of f in which the median is given as 100%. The variation of f at all sites of the body is 3% to 11% in terms of average absolute deviation. The calculation difference is obtained by the formula of body thickness×average absolute deviation. Where the calculation difference is within the above range, clinical practices will be influenced to a small extent. Thus, this study will provide an effective method for determining body thickness.

著者

都能 和俊 橋本 幸太郎 山中 良太 有森 秀夫

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.2, pp.174-182, 2019 (Released:2019-02-20)

参考文献数

12

被引用文献数

3 2

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This study aimed to evaluate the effect of pulmonary arteriovenous computed tomography (CT) value and CT value difference on the pulmonary arteriovenous automatic extraction ability of a medical workstation. We classified patients who previously underwent contrast-enhanced CT as those with a pulmonary arteriovenous CT value difference of <50 Hounsfield unit (HU) and ≥100 HU. The groups were further divided into four subgroups each, with a total of eight groups, based on low pulmonary arteriovenous CT values of 200 or more and <250 HU, 250 or more and <300 HU, 300 or more and <350 HU, and 350 HU or more. A radiographer conducted a visual evaluation, and we judged whether it could extract pulmonary arteries A1–A10 and pulmonary veins V1–V10 without errors. When the CT value difference was <50 HU, the low pulmonary arteriovenous CT value of 200 or more and <250 HU significantly decreased the extraction ability compared with the ≥350 HU group (p<0.05), but when the CT value difference was ≥100 HU, no difference in the CT value was found. The pulmonary arteriovenous CT value and CT value difference affect the pulmonary arteriovenous automatic extraction ability of the medical workstation, but revision by the creator is necessary because misrecognition is included even if a CT value and CT value difference is high.

著者

藤淵 俊王 藤田 克也 五十嵐 隆元 西丸 英治 堀田 昇吾 桜井 礼子 小野 孝二

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.77, no.2, pp.160-171, 2021 (Released:2021-02-20)

参考文献数

21

被引用文献数

2

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Purpose: To investigate the actual condition of the crystalline lens equivalent dose and effective dose according to the type of job and the type of duties in a medical institution. We also sought to clarify effective exposure reduction strategies. Methods: Equivalent crystalline lens doses, effective doses, job type, and duties for 8656 persons · year were obtained from 17 medical facilities. We analyzed the relationship between the effective dose and the crystalline lens equivalent dose in uniform exposure control and non-uniform exposure control conditions. Exposure data were obtained for 13 unique job types and duties. Results: The ratio of the lens equivalent dose to the effective dose of non-uniform exposure managers was 2 to 6 times and varied depending on the occupation. The percentage of persons whose annual lens equivalent dose exceeded 20 mSv was 4.75% for medical doctors, 1.17% for nurses, and 0.24% for radiological technologists. Highly exposed tasks included doctors in cardiology and gastroenterology performing angiography and endoscopy, nurses in endoscopy, and radiological technologists in radiography and CT examinations. Conclusion: Thorough unequal exposure control for operations with high crystalline lens exposure, radiation protection education, and effective use of proper personal protective equipment such as the use of radiation protection glasses may reduce lens exposure levels.

著者

室 伊三男 清水 俊太郎 塚本 ひかり

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.78, no.1, pp.13-22, 2022

被引用文献数

3

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<p>【目的】深層学習によるモーションアーチファクト(以下,アーチファクト)削減のアプローチが脳MR画像に有効かを検証する.【方法】本研究ではアーチファクトを含んだ画像と含んでいない画像が学習データとして大量に必要である.臨床画像で学習データを集めるには多くの労力と時間を要して困難である.われわれは脳のアーチファクト画像をシミュレーションによって作成した.ボランティア20人の動きのない頭部画像を取得し,この画像を使用してアーチファクトの異なる画像をシミュレーションによって作成して深層学習を行う.得られた学習モデルのアーチファクト除去効果の検証は,別途テストデータを作成し,テストデータの入力画像と出力画像間のピーク信号対雑音比(peak signal-to-noise ratio: PSNR)と構造的画像類似性(structural similarity: SSIM)を3種類のデノイジング手法で比較した.使用したニューラルネットワークはU-shaped fully convolutional network(U-Net),denoising convolutional neural network(DnCNN)とwide inference network and 5 layers Residual learning and batch normalization(Win5RB)である.【結果】アーチファクト除去効果はU-Netが最も高く,SSIMの平均値は0.978, PSNRの平均値は32.5であった.【結語】本法は脳MRI画像の画質を劣化させずにアーチファクトを軽減できる有効な方法である.</p>

著者

水谷 貴史 山田 浩司 上村 正信 宇都 辰郎

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.49, no.7, 1993

著者

谷川原 綾子 辻 真太朗 福田 晋久 西本 尚樹 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.72, no.3, pp.203-208, 2016

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<i>Purpose</i>: The purpose of this study is to investigate the differences in the notation of technical terms and their meanings among three terminologies in Japanese radiology-related societies. <i>Materials and Methods</i>: The three terminologies compared in this study were "radiological technology terminology" and its supplement published by the Japan Society of Radiological Technology, "medical physics terminology" published by the Japan Society of Medical Physics, and "electric radiation terminology" published by the Japan Radiological Society. Terms were entered into spreadsheets and classified into the following three categories: Japanese notation, English notation, and meanings. In the English notation, terms were matched to character strings in the three terminologies and were extracted and compared. The Japanese notations were compared among three terminologies, and the difference between the meanings of the two terminologies radiological technology terminology and electric radiation terminology were compared. <i>Results and Discussion</i>: There were a total of 14,982 terms in the three terminologies. In English character strings, 2,735 terms were matched to more than two terminologies, with 801 of these terms matched to all the three terminologies. Of those terms in English character strings matched to three terminologies, 752 matched to Japanese character strings. Of the terms in English character strings matched to two terminologies, 1,240 matched to Japanese character strings. With regard to the meanings category, eight terms had mismatched meanings between the two terminologies. For these terms, there were common concepts between two different meaning terms, and it was considered that the derived concepts were described based on domain.

著者

秋山 宣行 中村 幸弘

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.65, no.8, pp.1073-1080, 2009-08-20 (Released:2009-09-01)

参考文献数

12

被引用文献数

3 5

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The purpose of this study was to correlate test bolus (TB) parameters and patient information and cardiac function with main bolus (MB) contrast density for 64-slice computed tomography, and to evaluate MB contrast density on a fixed injection rate, in comparison with an injection rate adjusted with TB parameters and patient information. A total of 256 patients underwent coronary CT angiography. In 126 patients (group 1), contrast material was administered at a flow rate of 4 ml/sec. The peak enhancement, the time needed to reach the peak of the TB and cardiac function of the MB were calculated for each patient in this group. The dependency of MB contrast attenuation on these parameters was evaluated. Significant correlations were obtained between the peak density of the TB and the patient’s body surface area (BSA) with the enhancement of MB. Furthermore, females showed a higher peak enhancement of MB than males. In view of the results of group 1, in the other 130 patients (group 2) injection protocols were computed by using regression analysis of each patient’s attenuation response to a TB and patient sex and BSA. Compared with group 1, the variations of MB contrast density of group 2 were reduced. Optimized contrast injection protocols are useful to reduce variations of MB contrast density, by taking these TB parameters and patient sex and BSA into account.

著者

打越 将人 植田 隆史 楫 靖 辻 昭夫 和田 昭彦 今岡 いずみ 松尾 導昌 丸山 克也 岡本 淳 滝沢 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.57, no.6, pp.639-644, 2001-06-20 (Released:2017-06-30)

参考文献数

13

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Studies have shown that diffusion MR imaging is a reliable method for the diagnosis of central nervous system diseases, especially acute cerebral infarction. Although echo planar imaging (EPI) is a promising tool for that purpose, it is vulnerable to susceptibility artifacts that are responsible for image distortion or signal loss. Our purpose in this study was to evaluate the usefulness of diffusion MR imaging with PSIF (reversed fast imaging SSFP) and split acquisition of fast-spin-echo signals for diffusion imaging (SPLICE) in the central nervous system (CNS). First, PSIF and SPLICE were applied to the phantoms. Each phantom, including acetone, acetic acid, and water, was analyzed for ADC based on SPLICE and for diffusion related coefficient (DRC) based on PSIF. The ADCs based on SPLICE were 4.36±0.89 * 10^<-3> mm^2/sec, 1.25±0.04 * 10^<-3> mm^2/sec, and 2.35±0.04 * 10^<-3> mm^2/sec, and the DRCs based on PSIF were 0.353±0.25, 0.178±0.07, and 0.273±0.018 for acetone, acetic acid, and water, respectively. These calculated ADCs based on SPLICE were well correlated with known diffusion coefficients, showing a correlation coefficient of 0.995. Second, PSIF and SPLICE were applied to the CNS. The advantage of PSIF and SPLICE was that susceptibility artifacts were reduced in the images of spinal cord and brain stem. PSIF was especially useful for diffusion MR imaging in the spinal cord. The disadvantage of SPLICE was the decreased SN ratio. We conclude that PSIF or SPLICE may be helpful when EPI diffusion MR imaging is insufficient.

著者

片岡 章勝 鈴木 斎 門間 正彦 渋谷 清和 栗田 勲 高橋 潤一郎 伊知地 宏志

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.51, no.10, 1995-10-01

著者

白石 順二 花岡 信子 宇都宮 あかね 上田 容子 津田 和良

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.1, pp.19-24, 1997-01-20 (Released:2017-06-29)

参考文献数

4

被引用文献数

2 1

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The relationship between gantry angle and the interval length of the scanning plane in computed tomography(CT)was studied with a simple geometrical calculation and the evaluation of clinical images obtained with a human phantom. The change in patient dose was also evaluated under various conditions of gantry angle. When the same table feeding distance was used, it was theoretically and experimentally demonstrated that the interval length of the scanning plane was significantly decreased as the gantry angle increased(e.g.about 10% at twenty-five degrees). Integrated patient dose during the sequence could be changed by various combinations of gantry angle and table feeding distance, and was decreased by setting an optimal interval length of scanning plane according to the gantry angle. We concluded that gantry angle had obvious effects on the interval length of the scanning plane and patient dose, and the new method of increasing the table feeding distance according to the gantry angle might be useful for the improvement of image reproduction and the reduction of patient dose.

著者

坪井 邦仁 福永 正明 山本 浩之

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.72, no.12, pp.1237-1244, 2016 (Released:2016-12-20)

参考文献数

17

被引用文献数

3 1

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Purpose: The purpose of this study was to investigate the effects of the metal artifact reduction using single energy metal artifact reduction (SEMAR) with a prosthetic hip joint in different field of view (FOV). Methods: A prosthetic hip joint was arranged at the center of the phantom. The phantom images were scanned by changing calibrated-FOV (C-FOV) of 240, 320, 400, and 500 mm. Those images were reconstructed by changing the display-FOV (D-FOV) of 120, 180, 240, and 320 mm. The metal artifact reduction with the SEMAR was evaluated by calculating the artifact index (AI) and its decrease ratio. Results: The AI of C-FOV (500 mm) and D-FOV (120, 180, 240, or 320 mm) were 15.8, 15.8, 15.7, and 14.4 with SEMAR. For changed C-FOV, the AI of C-FOV (240 mm) was significantly higher than any other C-FOVs. The AI of C-FOV (240 mm) was 29.8–30.0 and that of the other C-FOV were 12.4–15.8 with SEMAR. In addition, the decrease ratio of AI was 52.2–54.1% for C-FOV (240 mm) and 58.9–73.2% for the other C-FOVs. Conclusion: Although the SEMAR decreased the metal artifact, the effect of reducing the metal artifact was affected by C-FOV.

著者

長船 勇一 小森 幹夫 長谷川 博己 中川 健治

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.20, no.1, pp.8-9, 1964-07-25

著者

村松 駿

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.77, no.1, pp.75-80, 2021 (Released:2021-01-20)

参考文献数

34

著者

谷川原 綾子 辻 真太朗 福田 晋久 西本 尚樹 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.72, no.3, pp.203-208, 2016 (Released:2016-03-20)

参考文献数

14

被引用文献数

2

---

Purpose: The purpose of this study is to investigate the differences in the notation of technical terms and their meanings among three terminologies in Japanese radiology-related societies. Materials and Methods: The three terminologies compared in this study were “radiological technology terminology” and its supplement published by the Japan Society of Radiological Technology, “medical physics terminology” published by the Japan Society of Medical Physics, and “electric radiation terminology” published by the Japan Radiological Society. Terms were entered into spreadsheets and classified into the following three categories: Japanese notation, English notation, and meanings. In the English notation, terms were matched to character strings in the three terminologies and were extracted and compared. The Japanese notations were compared among three terminologies, and the difference between the meanings of the two terminologies radiological technology terminology and electric radiation terminology were compared. Results and Discussion: There were a total of 14,982 terms in the three terminologies. In English character strings, 2,735 terms were matched to more than two terminologies, with 801 of these terms matched to all the three terminologies. Of those terms in English character strings matched to three terminologies, 752 matched to Japanese character strings. Of the terms in English character strings matched to two terminologies, 1,240 matched to Japanese character strings. With regard to the meanings category, eight terms had mismatched meanings between the two terminologies. For these terms, there were common concepts between two different meaning terms, and it was considered that the derived concepts were described based on domain.

著者

植村 修 浅井 英博 稲垣 良美 青木 豊 新田 義勝 安藤 嘉康

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.33, no.3, 1977