日本放射線技術学会雑誌
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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72 巻, 3 号
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  • 放射線技術学に関する用語集の日本語表記と意味記述に関する比較
    谷川原 綾子, 辻 真太朗, 福田 晋久, 西本 尚樹, 小笠原 克彦
    2016 年 72 巻 3 号 p. 203-208
    発行日: 2016年
    公開日: 2016/03/20
    DOIhttps://doi.org/10.6009/jjrt.2016_JSRT_72.3.203
    ジャーナル フリー
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    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.
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  • PET 装置における空間分解能補正の効果および精度の検証
    甲谷 理温, 小田島 智, 松友 紀和, 神谷 貴史, 水田 哲郎, 大西 英雄
    2016 年 72 巻 3 号 p. 209-217
    発行日: 2016年
    公開日: 2016/03/20
    DOIhttps://doi.org/10.6009/jjrt.2016_JSRT_72.3.209
    ジャーナル フリー
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    Purpose: Recently, the quality of positron emission tomography (PET) images has rapidly improved using resolution recovery algorithm with point spread function (PSF). The aim of this study was to investigate the accuracy of the resolution recovery algorithm using three different PET systems. Methods: Three PET scanner models, the GE Discovery 600 M (D600M), SIEMENS Biograph mCT (mCT), and SHIMADZU SET-3000GCT/X (3000GCT) were used in this study. The radial dependences of spatial resolution (full width at half maximum: FWHM) were obtained by point source measurements (0.9 mmφ). All PET data were acquired in three-dimensional (3D) mode and reconstructed using the filtered back projection (FBP) , 3D-ordered subsets expectation maximization (3D-OSEM or dynamic row-action maximum likelihood algorithm) , and 3D-OSEM+PSF (PSF) algorithms. Two indicators, aspect ratio (ASR) and resolution recovery ratio (RRR), were calculated from measured FWHMs and compared among the three PET scanners. Results: In D600 and 3000GCT, distortions of the radial direction were slightly increased at circumference of field of view (FOV). On the other hand, random distortions were occurred in both radial and tangential direction in mCT. ASRs calculated from 3D-OSEM images at circumference of FOV were 2.06, 1.22, and 2.04 on D600M, mCT, and 3000GCT, respectively. ASR improved with PSF in all PET scanners. On the other hand, RRR with PSF were calculated 57.6%, 61.4%, and 31.6%, respectively. Conclusion: Our results suggest that the spatial resolutions of PET images could be improved with PSF algorithm in all PET systems; however, effect of PSF was different depending on PET systems. Furthermore, PSF algorithm could not completely improve spatial resolutions in circumference of FOV.
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  • デリバリFDG-PET/CT におけるTrue count rate 実測法による収集時間決定の有用性
    三浦 頌太, 小田島 智
    2016 年 72 巻 3 号 p. 218-226
    発行日: 2016年
    公開日: 2016/03/20
    DOIhttps://doi.org/10.6009/jjrt.2016_JSRT_72.3.218
    ジャーナル フリー
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    A stable quality of delivery 18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) requires suitable acquisition time, which can be obtained from an accurate true count of 18F-FDG. However, the true count is influenced by body mass index (BMI) and attenuation of 18F-FDG. In order to remove these influences, we have developed a new method (actual measurement method) to measure the actual true count rate based on sub-pubic thigh, which allows us to calculate a suitable acquisition time. In this study, we aimed to verify the acquisition count through our new method in terms of two categories: (1) the accuracy of acquisition count and (2) evaluation of clinical images using physical index. Our actual measurement method was designed to obtain suitable acquisition time through the following procedure. A true count rate of sub-pubic thigh was measured through detector of PET, and used as a standard true count rate. Finally, the obtained standard count rate was processed to acquisition time. This method was retrospectively applied to 150 patients, receiving 18F-FDG administration from 109.7 to 336.8 MBq, and whose body weight ranged from 37 to 95.4 kg. The accuracy of true count was evaluated by comparing relationships of true count, relative to BMI or to administered dose of 18F-FDG. The PET/CT images obtained by our actual measurement method were assessed using physical index. Our new method resulted in accurate true count, which was not influenced by either BMI or administered dose of 18F-FDG, as well as satisfied PET/CT images with recommended criteria of physical index in all patients.
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  • Web camera を用いた高線量率小線源治療装置の品質保証システム
    廣瀬 麻子, 上田 悦弘, 大平 新吾, 五十野 優, 辻井 克友, 乾 翔輝, 正岡 祥, 谷口 真, 宮崎 正義, 手島 昭樹
    2016 年 72 巻 3 号 p. 227-233
    発行日: 2016年
    公開日: 2016/03/20
    DOIhttps://doi.org/10.6009/jjrt.2016_JSRT_72.3.227
    ジャーナル フリー
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    Purpose: The quality assurance (QA) system that simultaneously quantifies the position and duration of an 192Ir source (dwell position and time) was developed and the performance of this system was evaluated in high-dose-rate brachytherapy. Methods: This QA system has two functions to verify and quantify dwell position and time by using a web camera. The web camera records 30 images per second in a range from 1,425 mm to 1,505 mm. A user verifies the source position from the web camera at real time. The source position and duration were quantified with the movie using in-house software which was applied with a template-matching technique. Results: This QA system allowed verification of the absolute position in real time and quantification of dwell position and time simultaneously. It was evident from the verification of the system that the mean of step size errors was 0.31±0.1 mm and that of dwell time errors 0.1±0.0 s. Absolute position errors can be determined with an accuracy of 1.0 mm at all dwell points in three step sizes and dwell time errors with an accuracy of 0.1% in more than 10.0 s of the planned time. Conclusion: This system is to provide quick verification and quantification of the dwell position and time with high accuracy at various dwell positions without depending on the step size.
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  • 自動露出制御機能を使用した胸部正面像における最適なexposure index 算出方法の検討
    柳田 智, 今花 仁人, 五味 勉, 西木 雅行
    2016 年 72 巻 3 号 p. 234-243
    発行日: 2016年
    公開日: 2016/03/20
    DOIhttps://doi.org/10.6009/jjrt.2016_JSRT_72.3.234
    ジャーナル フリー
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    Fifty posterior-anterior chest radiographs taken using an auto exposure control were evaluated in order to find an optimum determination method of the exposure index (EI). Four types of the relevant image regions were tested: (a) full image, (b) central 25% area, (c) full image excluding direct x-ray area, and (d) pulmonary area only, whereas four types of the value of interest (VOI) were adopted to each relevant image region: mean, median, mode, and middle. When the target EI was determined as the average of the 50 images, the deviation index (DI) was within ±1.0 only if pulmonary area was selected as the relevant image region, with the VOI of mean, median, and middle. This result strongly suggests that pulmonary area should be selected as the relevant image region of an EI when an auto exposure control is used.
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ノート
  • X 線CT 装置の半価層測定における非接続形X 線出力アナライザ専用鉛ケースの開発
    赤石 泰一, 武田 浩光, 金澤 仁幸, 吉井 勇治, 浅沼 治
    2016 年 72 巻 3 号 p. 244-250
    発行日: 2016年
    公開日: 2016/03/20
    DOIhttps://doi.org/10.6009/jjrt.2016_JSRT_72.3.244
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    Measurement of the half-value layer (HVL) is a difficult task in computed tomography (CT) , because a nonrotating X-ray tube must be used. The purpose of this study is to develop a lead-covered case, which enables HVL measurements with a rotating CT X-ray tube. The lead-covered case was manufactured from acrylic and lead plates, which are 3 mm thick and have a slit. The slit-detector distance can be selected between 14 mm and 122 mm. HVL measurements were performed using a wireless X-ray output analyzer “Piranha.” We used the following exposure conditions: tube voltages of 80, 100, and 120 kV; a tube current of 550 mA; and an exposure time of 1.0 s. The HVLs were measured by using the following two methods: (a) Nonrotating method—a conventional method that uses the nonrotating exposure mode. (b) Rotating method—a new method that uses the lead-covered case and the rotating exposure mode. As a result, when the slit-detector distance was 58 mm, the HVL values obtained by the nonrotating and rotating methods were 4.38 and 4.24 mmAl at 80 kV, 5.51 and 5.37 mmAl at 100 kV, 6.61 and 6.48 mmAl at 120 kV, respectively. A lead-covered case, which enables the measurement of the HVL in a rotating X-ray tube, was developed. The case is useful in measuring the HVLs at facilities that cannot fix the X-ray tube.
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  • 肺定位放射線治療における積算線量分布の事後評価法の検討
    今江 禄一, 早乙女 直也, 竹中 重治, 渡邉 雄一, 竹内 幸浩, 矢野 敬一, 中野 正寛, 芳賀 昭弘, 高橋 渉, 山下 英臣, ...
    2016 年 72 巻 3 号 p. 251-260
    発行日: 2016年
    公開日: 2016/03/20
    DOIhttps://doi.org/10.6009/jjrt.2016_JSRT_72.3.251
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    Purpose: The purpose of this study was to evaluate a post-analysis method for cumulative dose distribution in stereotactic body radiotherapy (SBRT) using volumetric modulated arc therapy (VMAT) . Method: VMAT is capable of acquiring respiratory signals derived from projection images and machine parameters based on machine logs during VMAT delivery. Dose distributions were reconstructed from the respiratory signals and machine parameters in the condition where respiratory signals were without division, divided into 4 and 10 phases. The dose distribution of each respiratory phase was calculated on the planned four-dimensional CT (4DCT). Summation of the dose distributions was carried out using deformable image registration (DIR), and cumulative dose distributions were compared with those of the corresponding plans. Results and discussion: Without division, dose differences between cumulative distribution and plan were not significant. In the condition where respiratory signals were divided, dose differences were observed over dose in cranial region and under dose in caudal region of planning target volume (PTV). Differences between 4 and 10 phases were not significant. Conclusion: The present method was feasible for evaluating cumulative dose distribution in VMAT-SBRT using 4DCT and DIR.
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教育講座―放射線部門をとりまく無線通信技術―
基礎講座―肝臓疾患(特に肝細胞がん)の診断から治療まで―
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