日本放射線技術学会雑誌
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
71 巻, 3 号
選択された号の論文の15件中1~15を表示しています
巻頭言
原著
  • 中澤 寿人, 内山 幸男
    2015 年 71 巻 3 号 p. 177-185
    発行日: 2015年
    公開日: 2015/03/20
    ジャーナル フリー
    We assessed the impact of source positional discrepancy on dose and dose distributions in Gamma Knife (GK) Perfexion (PFX) stereotactic radiosurgery. A spherical phantom dedicated in GK machine was used and irradiated by 2 Gy in each position moved at an interval of 0.1 mm from its original position using three types of collimators (4, 8, 16 mm) to evaluate the changes of dose. In addition, to obtain the dose distributions, radiochromic film was inserted in the phantom and irradiated by 6 Gy in each position moved at an interval of 1 mm from its original position using three types of collimators. A distance-to-agreement analysis (DTA) was performed to compare isodose lines from 10% to 90% of dose distributions between the original and deviated position. As a result, when the source moved toward the discrepancy from the center of the collimator, the dose and dose distributions discrepancies increased according to the degree of discrepancy. Especially in 4-mm collimator, 0.5 mm discrepancy caused dose reduction of 5%. On the other hand, 0.5 mm discrepancy showed merely dose differences less than 0.5% in 8 mm and 16 mm collimators. Regarding dose distributions, 1 mm discrepancy in all collimators showed little changes in DTA within 1 mm on average.
  • 辻 真太朗, 福田 晋久, 谷川原 綾子, 西本 尚樹, 本間 勝美, 小笠原 克彦
    2015 年 71 巻 3 号 p. 186-193
    発行日: 2015年
    公開日: 2015/03/20
    ジャーナル フリー
    Purpose: In 1994, Japanese Society of Radiological Technology (JSRT) constructed the lexicon in the field of radiologic technology. However, recently, latest lexicon is not updated yet. The purpose of this article is to compare the terminologies in clinical medicine with the others and to consider reconstructing the lexicon in the radiological technology. Materials and Methods: Our study selected three categories from the database of the academic society. These three groups were Clinical medicine (hereafter CM, 167 societies, includes JSRT), Psychology / Education (hereafter P/E, 104 societies), and Comprehensive synthetic engineering (hereafter CSE, 40 societies). First, all societies were surveyed to know whether there were any lexicon in their official website. Second, these terminologies were surveyed on the following criteria: (a) Media of lexicon, (b) Number of terms, (c) File type of lexicon, (d) Terms translated into English, (e) Way of searching terms, and (f) Number of committees of the terminology. Results: Lexicon in CM, P/E, and CSE had 20, 4, and 7. Compared with P/E and CSE, CM showed the following trends: (a) used electronic media frequently, (b) stored large number of terms (about 5,000 to 11,000), (c) enabled to download frequently, and (d) used the alphabet and Japanese syllabary order frequently. Conclusions: Compared with the lexicon of P/E and CSE, terminology in CM tended to adopt the electronic media of lexicon and to have large number of terms. Additionally, many lexicons were expressed in English terms along with Japanese terms. Following massive lexicon of SNOMED-CT and RadLex, it is necessary to consider applying the web-based term searching and an ontological technique to the lexicon of radiological technology.
ノート
  • 庄司 友和, 加藤 秀起, 勝木 葉子, ガラハー 美樹
    2015 年 71 巻 3 号 p. 194-200
    発行日: 2015年
    公開日: 2015/03/20
    ジャーナル フリー
    The patients in NICU (Neonatal Intensive Care Unit) are more likely to get portable X-ray often while they are in the hospital. These patients potentially may get relatively more exposure dose in total in a short period of time. We developed a software to analyze the exposure dose for the patients in the incubator, which is called PIETAII (Patient Information of Exposure dose Total Analysis in NICU). Then, we compared the accuracy of PIETAII and SDEC (surface dose evaluation code) based on customary method. Using the 5 cm body thickness with exposure setting of 50 kV, 1 mAs, relative error between the customary method and the calculated dose by PIETAII and SDEC were 1.96% and 32.35%, respectively. PIETAII is a useful software to estimate the entrance surface dose using the exposure setting.
  • 北 章延, 小野口 昌久, 杉本 勝也, 土田 龍郎, 戸井 章子, 岸本 貴宏, 嶋田 真人, 安達 登志樹
    2015 年 71 巻 3 号 p. 201-207
    発行日: 2015年
    公開日: 2015/03/20
    ジャーナル フリー
    The undershooting artifact occurs using the filtered back projection (FBP) method. This artifact is influenced by a ramp filter. Thereby, the fall of the target accumulation and a deficit arise and it becomes a clinical problem. We developed a new image reconstruction method based on the FBP method to delete the undershooting artifact of FBP. The image quality of the FBP method is equivalent to that obtained by an evaluation using a digital phantom. The two segmentation and ordinary FBP methods were evaluated in terms of hot contrast, cold contrast, coefficient of variation (%CV), and root mean square uncertainty (%RSMU). The two segmentation FBP method showed equivalent values of hot contrast, % CV, and% RSMU compared with those of the ordinary FBP method. With a threshold level value, cold contrast sharply changed. However, when the threshold level of the two segmentation FBP method was set as the proper value, 90% contrast was obtained. It is necessary to set a threshold level as a proper value using the two segmentation FBP methods. I thought that it can delete an artifact in a simple way, without impairing the image quality. However, it is an examination of only a digital phantom this time. Before using it clinically, one has to use and verify a real phantom.
臨床技術
  • 金田 秀一, 竹村 直治, 吉村 良
    2015 年 71 巻 3 号 p. 208-215
    発行日: 2015年
    公開日: 2015/03/20
    ジャーナル フリー
    This study was conducted to investigate whether preoperative estimation of the cerebral blood flow (CBF) by single photon emission computed tomography (SPECT) can allow identification of patients at risk for hyperperfusion (HP) after carotid artery stenting (CAS). In 40 patients scheduled to undergo CAS, the CBF and cerebral vascular reserve (CVR) were measured prior to the intervention by resting and acetazolamide loading SPECT. The SPECT findings were classified into 4 types: Type 1, normal CBF in the resting state (CBFrest) and normal CVR; Type 2, normal CBFrest and reduced CVR; Type 3, reduced CBFrest and reduced CVR; and Type 4, reduced CBFrest and normal CVR. Four patients presented with HP after CAS. Patients with high proportions of Type 2 and Type 3 had high risk of HP after CAS. (ROC analysis: AUC=0.94, cutoff value of 75.8% had PPV of 75.0%, NPV of 97.2% and odds ratio of 105.0). The proportions of Type 2 and Type 3 in preoperative SPECT may identify patients at risk for the development of HP.
  • 寺下 貴美, 小笠原 克彦
    2015 年 71 巻 3 号 p. 216-221
    発行日: 2015年
    公開日: 2015/03/20
    ジャーナル フリー
    The knowledge of radiological technologists is expected to increase with medical development. However, it is impossible to impart all knowledge in a limited time frame. Problem-based learning (PBL) is a learning methodology to solve it. In the PBL, students can gain problem-solving abilities by acquiring necessary knowledge from clinical cases and applying them during practice. We here report to implement the PBL in radiography practice. This practice opened a course at 2nd semester of third-grade students in our school. The practice flow includes presentation of clinical case and a survey of necessary knowledge, group work, radiography, reflection through practice, and deliberation of different cases. The clinical case was the radiography of an emergency patient. The evaluation items were about knowledge, skill, and attitude. By the PBL practice, students could realize a clinical scene, and discover considerable points unwritten in textbooks.
  • 平島 英明, 梅津 芳幸, 福永 淳一, 廣瀬 貴章, 永田 弘典, 毛利 一彩, 中村 和正, 平田 秀紀
    2015 年 71 巻 3 号 p. 222-229
    発行日: 2015年
    公開日: 2015/03/20
    ジャーナル フリー
    Purpose: The purpose of this study was to evaluate the effect of prostate matching on dose distribution using kilovolt cone beam computed tomography (kV-CBCT) with image guided radiation therapy for prostate cancer. Materials and method: Sixteen prostate cancer patients were treated with intensity modulated radiation therapy to 76 Gy at 2 Gy per fraction in 38 fractions. Daily target localization was performed using “bone matching” and “prostate matching” based on planning CT and kV-CBCT. Prostate dose coverage was assessed by the proportion of the CTV fully encompassed by 95%, 98% isodose lines, and mean dose lines. As for rectal and bladder, dose coverage was assessed by volumes which received 40 Gy, 60 Gy, 70 Gy, 75 Gy and mean dose at treatment. And we calculated the tumor control probability (TCP) and normal tissue complication probability (NTCP), accordingly. They were compared to the bone and prostate matching image. Result: Our study found an improvement in dose usage in CTV and bladder which enabled us to compare the bone matching image and the prostate matching image. However, it did not improve dose usage in the rectal. Then we chose patients who were a large shift from bone matching image to prostate matching image. As a result, rectal dose and NTCP were reduced. Discussion: Prostate matching is useful and safe when compared to bone matching because of improving CTV dose usage and reducing dose rectal and bladder.
  • 伊原 陸, 伊藤 幸平, 寺下 貴美, 布施 善弘
    2015 年 71 巻 3 号 p. 230-236
    発行日: 2015年
    公開日: 2015/03/20
    ジャーナル フリー
    This study aimed to reduce contrast medium dose without reducing the diagnostic capability of computed tomography (CT) angiography of the head. We evaluated the advanced statistical iterative reconstruction (ASiR) settings to adjust to low tube voltage CT. A syringe phantom was constructed using dilute contrast medium and was imaged at tube voltages of 80–120 kV. The iodine volumes, CT values, and image noise were measured in these images. The noise-power spectrum and modulation transfer function were measured from quality assurance phantom images that had been obtained using the tube voltage selected after considering the image noise results as described above and reconstructed using different ASiR rate settings and convolution kernels. Our results suggested that imaging at 100 kV could reduce the contrast medium dose by 14%, compared with imaging at 120 kV, and that the resulting image quality could equal that of conventional imaging by performing reconstruction at a 40% ASiR rate and detail kernel.
  • 高柳 知也, 佐野 始也, 近藤 武, 天沼 誠, 石坂 和真, 関根 貴子, 松谷 英幸, 森田 ひとみ, 新井 雄大, 高瀬 真一
    2015 年 71 巻 3 号 p. 237-245
    発行日: 2015年
    公開日: 2015/03/20
    ジャーナル フリー
    Purpose: The purpose of this study is to validate the clinical usefulness of Advanced Patient Motion Correction (APMC) reconstruction when motion artifacts were observed in a prospective ECG-gated coronary CT angiography (CCTA), which was acquired by low tube current scanning with full reconstruction using 320-row area detector CT (0.275 s/rot.). Methods: Of 530 consecutive CCTA, we selected 119 patients (M/F: 71/48, Age: 69 ± 11 y, BMI: 23.5 ± 2.5) with (RR-PQ)≥968 ms before scanning, and performed a CCTA with low tube current scanning [30% of usual tube current (30%mA)], adaptive iterative dose reduction 3D, and full reconstruction. Image quality for motion artifacts was subjectively evaluated using a 3-point scale (excellent, acceptable, and unacceptable). Results: Of 119, 102 CCTA had “excellent” images (group A) and 17 had “acceptable” images (group B). The APMC and half reconstruction were retried in the 17 CCTA with “acceptable” images. Finally, all CCTA became “excellent” images. The RR-PQ of group B during scanning (966±80 ms) was significantly (P = 0.0001) shorter than group A (1,088 ± 123 ms). Each image noise (standard deviation of CT value) of aorta, left atrium, and left ventricle was 21.7±2.3, 24.7±2.3, 24.5±2.4 in full, 25.7±2.2, 29.0±3.4, 28.2±2.7 in APMC, and 30.4±2.8, 34.3±4.2, 33.3±2.9 HU in half reconstruction. Mean dose-length product of all patients was 66.2±34.4 mGy · cm. Conclusion: “Excellent” CCTA images can be obtained in 85.7% of patients with (RR-PQ)≥968 ms by full reconstruction. APMC is useful for motion artifacts and image noise reduction when patient' s HR increases during scanning rather than half reconstruction.
第70回総会学術大会シンポジウム3
教育講座―モンテカルロシミュレーションの放射線技術への利用―
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