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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65 巻, 4 号
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  • SPECT評価用ペーパーファントムの作製方法に関する検討
    市川 肇
    2009 年 65 巻 4 号 p. 421-429
    発行日: 2009/04/20
    公開日: 2009/05/02
    DOIhttps://doi.org/10.6009/jjrt.65.421
    ジャーナル フリー
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    Objective: The purpose of this study was to find a method of creating a paper phantom for SPECT evaluation. The method included preparing paper surface sources with an ink-jet printer and placing them evenly spaced apart. Methods: We prepared a paper surface source with the ink-jet printer fixed on an ink cartridge laced with 99mTc. We then set it and Styrofoam in turn, to develop a paper phantom for SPECT evaluation. The evaluation method was 1) accuracy evaluation of the paper surface source, 2) activity control, 3) pitch of the paper surface source, 4) activity concentration of ink, 5) spot phantom. Results: 1) accuracy was good, 2) activity control was possible, 3)% root mean square uncertainty (%RMSU) was equal to or less than 5% on average, when the pitch of the paper surface source did not exceed 10 mm. 4) The radioactivity concentration was radioactivity 9.7 kBq/cm2 of the paper surface source per radioactivity 37 MBq/ml of the ink. 5) We were able to create a spot phantom easily. Discussion: The pitch of the paper surface source must not exceed 10 mm to use a paper phantom for SPECT evaluation. This is a simple method to control activity density in phantom experiments.
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  • Image quality figureの閾値によるComputed Radiographyでの適正線量の推定
    望月 安雄, 阿部 慎司, 山口 弘次郎
    2009 年 65 巻 4 号 p. 430-437
    発行日: 2009/04/20
    公開日: 2009/05/02
    DOIhttps://doi.org/10.6009/jjrt.65.430
    ジャーナル フリー
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    We estimated the optimum dose for imaging with a computed radiography (CR) system at two different pixel sizes based on the area under curve (AUC) in receiver operating characteristic (ROC) analysis and image quality figure (IQF). Samples for ROC analysis were prepared as follows. Acryl beads, 2.0 mm in diameter, were placed on a 50.0 mm tough water phantom that was fitted with a 20.0 mm Al filter (SID 200 cm, tube voltage 80 kV). The dose level at which the film density of the screen-film system (SRO250/SRG) was 1.0±0.05 served as the reference dose (0.69μC/kg). Five samples were prepared by multiplying the reference dose by 1/4, 1/2, 1, 2, and 4. The samples for image quality evaluation on the basis of IQF were prepared under identical conditions. A contrast-detail (C-D) phantom was placed on a 50.0 mm tough water phantom and images were taken. The contrast threshold of these samples was determined by 10 film readers, the same as those for the ROC analysis. When the significance of differences in the AUC was tested by the paired t-test (two-sided) and the Jackknife method, significant differences were noted between the reference dose and the 1/4 or 4-times dose at the standard pixel size (0.175 mm) and smaller pixel size (0.0875 mm) size, while no significant difference was noted between the reference dose and the 1/2 or 2-times dose. In terms of IQF, no significant difference was noted between standard and smaller pixel sizes (paired t-test). The IQF data indicate that the dose level for imaging with CR can be reduced by about 30% from the reference dose.
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  • マルチモダリティ画像を用いた包括的画像処理法による肝臓病変検出法の開発–プロファイルを用いた画素単位相互相関法–
    井上 聖, 大倉 保彦, 川下 郁生, 伊東 克能, 松永 尚文, 真田 泰三, 秋山 實利, 石田 隆行
    2009 年 65 巻 4 号 p. 438-450
    発行日: 2009/04/20
    公開日: 2009/05/02
    DOIhttps://doi.org/10.6009/jjrt.65.438
    ジャーナル フリー
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    Imaging techniques such as high magnetic field imaging and multidetector-row CT have been markedly improved recently. The final image-reading systems easily produce more than a thousand diagnostic images per patient. Therefore, we developed a comprehensive cross-correlation processing technique using multi-modality images, in order to decrease the considerable time and effort involved in the interpretation of a radiogram (multi-formatted display and/or stack display method, etc). In this scheme, the criteria of an attending radiologist for the differential diagnosis of liver cyst, hemangioma of liver, hepatocellular carcinoma, and metastatic liver cancer on magnetic resonance images with various sequences and CT images with and without contrast enhancement employ a cross-correlation coefficient. Using a one-dimensional cross-correlation method, comprehensive image processing could be also adapted for various artifacts (some depending on modality imaging, and some on patients), which may be encountered at the clinical scene. This comprehensive image-processing technique could assist radiologists in the differential diagnosis of liver diseases.
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臨床技術
  • End User Computingによる放射線部門情報化の取り組み
    山口 勝也, 加藤 勤, 室田 真希子, 河内 秀行, 三浦 信二, 石川 みどり, 大廣 美香
    2009 年 65 巻 4 号 p. 451-455
    発行日: 2009/04/20
    公開日: 2009/05/02
    DOIhttps://doi.org/10.6009/jjrt.65.451
    ジャーナル フリー
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    In recent years, due to the advanced computerization of medical institutions, systems such as radiology information system (RIS) and reporting have been used extensively also at radiology departments. However, the introduction of these systems will need a great amount of money, and the systems are not yet introduced in our hospital. On the contrary, thanks to the sophistication and price reduction of personal computers (PCs), there is now found a rapid expansion of end user computing (EUC) in which users of a system actively build and manage the system of their duties. Under these circumstances, in order to assist the duties at low costs, we worked the computerization of duties done at our Radiology Department by using the EUC. Specifically, we used software of general-purpose database to build the system with functions dealing with records on implementing medical examinations and treatments, examination booking and diagnostic imaging report. This system which has been developed according to details of conventional duties and requests from medical personnel makes it possible to alleviate the duties which were done manually.
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  • 動体追跡照射における体内マーカ追跡用透視X線による皮膚入射線量の推定–正弦波呼吸モデルによるシミュレーション–
    河窪 正照, 安井 謙一郎, 神崎 竜二, 大石 誉奈, 真田 泰三
    2009 年 65 巻 4 号 p. 456-461
    発行日: 2009/04/20
    公開日: 2009/05/02
    DOIhttps://doi.org/10.6009/jjrt.65.456
    ジャーナル フリー
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    The real-time tumor-tracking radiotherapy system includes two sets of fluoroscopes that detect the fiducial markers in or near the tumor constantly during radiotherapy. The treatment beam is irradiated to the tumor only when fiducial markers are located in the target position. Treatment time is extended in case of large respiratory tumor motion. A high-power fluoroscopic X-ray is required in the case of fiducial markers in parenchymal organs with heavy X-ray attenuation. It was a concern that radiodermatitis was caused by an increasing entrance skin dose from the fluoroscopic X-ray. In order to estimate the entrance skin dose from the fluoroscopic X-ray, we measured the entrance skin dose rate through the use of a method recommended by the Japanese Society of Radiological Technology. We applied sine wave simulation to resemble the respiratory motion of the tumor. In conclusion, we confirm that entrance skin dose from fluoroscopy during RTRT is lower than the threshold dose for radiodermatitis.
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  • 呼吸停止下における高速回転SPECT撮像法の検討–3 検出器・2 検出器型装置の比較–
    大石 誉奈, 岩永 秀幸, 小池 正紘, 米沢 鉄平, 菅 一能
    2009 年 65 巻 4 号 p. 462-469
    発行日: 2009/04/20
    公開日: 2009/05/02
    DOIhttps://doi.org/10.6009/jjrt.65.462
    ジャーナル フリー
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    Background: Because lung perfusion Tc-99m MAA of SPECT is generally acquired under the non-breath-hold condition, SPECT image quality is degraded for respiratory lung motion. To solve this problem, a new acquisition mode would need to be developed. We suggest that the acquisition mode is the detector rotating at high speed during the deep breath-hold condition and 20 sec. This acquisition method is known as high-speed detector rotation-multiplied projection single photon emission computed tomography (HSRMP-SPECT). Detail is reconstructed from projection data added while projection data are acquired several times under deep breath-hold sets. Purpose: The HSRMP-SPECT technique has been developed under the triple-head system. However, the triple-head system is a small field of view. Thus a description of the entire lung area was impossible under the deep breath-hold condition. The HSRMP-SPECT technique seems needed to make the shift to dual-head system, because the generally dual-head system has a large field of view. We were compared triple-head system with dual-head system, and researched some parameter. Result: With lung perfusion HSRMP-SPECT using the dual-head system, description of the entire lung area possible. The triple-head system of 5 projection data sets and dual-head system of 6 projection data sets nearly equaled the total count, and also the coefficient of variation is nearly same. Therefore, we were able to make the triple-head system to the dual-head system the shift on HSRMP-SPECT.
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