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JSMP2001 大会長 稲邑 清也 |
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招待講演 ９月２８日（金）11:10〜12:10 Ａ会場 座長 井上俊彦（大阪大学） 「Present and Future of Brachytherapy」 Dr. Marco Zaider, Ph.D. (Memorial Sloan-Kettering Cancer Center) |
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特別講演 ９月２９日（土）14:30〜15:20 Ａ会場 座長 稲邑清也（大阪大学） 「外科手術と情報科学」 越智 隆弘 （大阪大学大学院医学系研究科長） |
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教育講演 ９月２８日（金）10:10〜11:00 Ａ会場 座長 松本政雄（大阪大学） 「超音波造影法の過去・現在・未来」 別府 慎太郎（大阪大学医用物理学講座 |
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シンポジウム ９月２８日（金）15:30〜17:30 Ａ会場 「臨床に役立つ医学物理を目指して」 司会 丸橋 晃、遠藤 真広 |
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放射線治療の立場から 内山 幸男(愛知がんセンター) | ||||||||
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放射線診断の立場から 東田 善治(九州大学医療技術短期大学部) |
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核医学の立場から 篠原 広行(東京都立保健科学大学) | ||||||||
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放射線防護の立場から 西沢 邦秀(名古屋大学) | ||||||||
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情報システム構築の立場から 渡辺 良晴(北海道大学医療技術短期大学部) |
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総会 ９月２８日（金）13:30〜14:30 Ａ会場 |
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医学物理士講習会 9月27日（木）14:00 〜 17:00 |
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理事会 9月27日(木) 17:30 〜 |
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評議員会 9月28日（金）12:10 〜 13:20 |
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一般口演 9月28日（金）8:50 〜 15:18 9月29日（土）8:50 〜 17:42 |
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懇親会 9月28日（金）18:00 〜 20:00 阪大病院１４Ｆ スカイレストラン |
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青少年のための講演会 9月30日（日）10:00 〜 16:00 ―医療における放射線―放射線は人類の敵か味方か― |
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| 受付開始 ８：１０〜 |
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開会の辞 ８：４０〜８：５０
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| I．一般口演 Ｘ線診断I 8:50 〜 9:26 座長 和田 真一 |
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1. 乳房撮影における照射野内のX線スペクトルの変化 "Variations of x-ray spectra in the mammographic radiation field" 宮島悟史、今川康太郎、松本政雄1) 阪大院・医・保健、阪大・医・保健1) We investigated variations of x-ray spectra in the mammographic radiation field. Nonuniformity of the half value layer (HVL) in the mammographic radiation field has been reported in the literature. This difference in the HVL indicates that x-ray spectra are different in the mammographic radiation field. Sources of variations of x-ray spectra were supposed to be the heel effect and different x-ray path lengths in inherent and added filter. Because of a steep target angle and a short target-film distance, the heel effect is pronounced in mammography. Moreover, the difference of the x-ray path length in the filter is also pronounced due to the short target-field distance. X-ray spectra, as a function of position in the mammographic radiation field, were obtained with a CdZnTe detector. The CdZnTe detector was employed because of its small size and its excellent response to low energy x-rays. The results show that the differences in x-ray spectra were apparent along the anode-ca! thode direction, but not along the direction being orthogonal to it. The differences along the anode-cathode direction indicate that selective absorption of low energy x-rays and of x-rays having energy just above K-absorption edge of molybdenum occur in the target and filter. |
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2. CdZnTe検出器を用いた診断用Ｘ線装置の90°散乱Ｘ線スペクトル測定の検討 "Discussion for measurement of 90°scattered x-ray spectra of diagnostic x-ray units using a CdZnTe detector" 松本政雄、小縣裕二、窪田英明、谷口 明1)、金森仁志2) 阪大・医・保健、東洋メディック1)、京都工繊大名誉教授2) By a Ge detector, we cannot measure directly the x-ray spectra produced at a large current like radiographic conditions. We have attempted to measure directly and 90°scattered diagnostic,computed tomography(CT) and mammographic x-ray spectra produced by each x-ray unit with a CdZnTe detector and some carbon scatterers. We discuss the measurement of 90°scattered x-ray spectra produced at a large current like radiographic conditions with a CdZnTe detector and some carbon scatterers. |
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3. ZnドープCdTe多結晶膜を変換層とするＸ線パネルセンサの評価 "Experimental evaluation of a flat-panel X-ray detector with the polycrystalline Zn-doped CdTe film" 徳田 敏、足立 晋、佐藤 敏幸、山田 敏志、 和泉良弘1)、 寺沼 修1)、山根康邦1) 島津製作所・基盤研、シャープ・ディスプレイ研1) We made a prototype flat-panel X-ray detector utilizing polycrystalline CdZnTe film, and evaluated its imaging performance with respect to leakage current, X-ray sensitivity, MTF and DQE. The detector incorporates a novel hybrid technique in which zinc-doped CdTe is pre-deposited onto a ceramic substrate and then connected with a TFT circuit substrate. The film thickness was about 300 um. The imaging area is composed of 512 x 384 pixels, with a pixel pitch of 150 mm. The measured leakage current was 90 pA/mm2(2 pA/pixel), and the sensitivity was 9E8 e-/mR/mm2 (2E7 e-/mR/pixel) at the bias field of 0.4 V/mm; the beam condition was 80 kV with 26-mm Al filtration. The MTF measured at 1 lp/mm was 0.80, and the DQE at 0 lp/mm was 0.34. The value of DQE will be improved further by increasing the thickness or density of the CdZnTe film. The CdZnTe flat-panel detector exhibits good MTF, which indicates that the detector is suitable for radiography. Although further improvements are required in DQE, the superior X-ray sensitivity is promising in terms of using the detector in fluoroscopic mode, because the electronic readout noise becomes relatively negligible. |
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II．一般口演 Ｘ線診断II 9:26 〜 10:02 座長 阿部 慎司 |
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4. マンモグラフィ用ファントム画像のウィナ-スペクトルの光学濃度依存性 "Optical density dependence of Wiener spectra of mammography phantom images" 松本政雄、一丸恭伸、末兼浩司、今村恵子1)、江原範重1)、金森仁志2) 阪大・医・保健、聖マ医大・放1)、京都工繊大名誉教授2) We measured Wiener spectra of mammography phantom images at any optical densities for different 5 mammography units and evaluated the detectability of mass phantoms in granularity to compare Wiener spectral values at any optical densities. As a result, the detectability of mass phantoms in granularity is superior at lower optical densities under 1.0. We think we must not take mammography images at higher optical densities to detect mass. |
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5. CRシステムにおける画像信号の鮮鋭度に対する散乱線の影響 "Influence of Scattered X rays on the Sharpness of Image Signal" 前田浩志、有村秀孝、松本政雄1)、金森仁志2) 広国大・保健医療、阪大・医1)、京都工繊大2) The purpose of this study is to investigate the influence of the scattered x rays on the sharpness of the image signal produced by a CR system. By using a 100-μm slit on the PMMA (Polymethyl methacrylate) for various thicknesses of 0.5, 5.5, 10.5, 15.5, and 20.5 cm, the slit images as a signal were acquired at tube voltages of 80 and 100 kV. The slit images were Fourier transformed to obtain the spatial frequency spectra normalized at a frequency of zero. As the thickness of PMMA increased, the spectral values for the slit images decreased. In particular, at spatial frequencies lower than 0.2 mm^-1, the spectral values rapidly decreased with the thickness of PMMA. In addition, all spectra normalized at a spatial frequency of 0.2 mm^-1 almost coincided. This shows that, at frequencies lower than 0.2 mm^-1, the scattered x rays give the different influence on the spectral values, but, at frequencies higher than 0.2 mm^-1, give the same influence. |
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6. びまん性肺疾患における経時的サブトラクションの有用性 "Usefulness of temporal subtraction for detection of interval changes of interstitial lung diseases" 大喜雅文、東田善治、豊福不可依、村中光1)、井手口忠光1) 、 宮島隆一1) 、田畑信幸1) 、赤澤史生1) 、池田尋隆1) 、桂川茂彦2) 、 土井邦雄3) 九大医短・診放、国立九医セ・放射1) 、日文理大・総研セ2) 、 シカゴ大・カートロスマン研3) To evaluate the clinical usefulness of a temporal subtraction technique for detection of interval changes of interstitial lung diseases, observer performance tests using receiver operating characteristic (ROC) analysis were carried out. Two thoracic radiologists selected one hundred pair of computed radiography(CR) chest radiographs (previous image and current image) from 34 cases with lung diseases of reticular, reticular infiltrative, reticular-linear, reticular-nodular, infiltrative, ground-glass, nodular and sclerotic. One hundred temporal subtraction images, 37 images without interval changes and 63 with interval changes were selected from these cases. Five experienced thoracic radiologists and two thoracic physicians participated in the observer performance studies. A pair of CR images was shown first without temporal subtraction image, and then it was shown with temporal subtraction image. Observers were asked to state their judgment regarding the confidence level on i nterval changes by using a continuous rating scale. Az (area under the ROC curve) values obtained from ROC analysis without and with temporal subtraction image were 0.78 and 0.90, respectively. The highest Az value was obtained for reticular-nodular lung diseases among the diseases. We conclude that the temporal subtraction can assist radiologists in the detection of interval changes of interstitial lung diseases on chest radiographs. |
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III 教育講演 10:10 〜 11:00 座長 松本 政雄 超音波造影剤の過去・現在・未来 大阪大学 別府 慎太郎 |
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IV 招待講演 11:10 〜 12:10 座長 井上 俊彦 Recent Progress and the Future of Brachytherapy Memorial Sloan-Kettering Cancer Center Dr.Marco Zaider, Ph.D. |
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評議員会 12:10 〜 13:30 |
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V 総 会 13:30 〜 14:30 2000年度論文賞表彰 |
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VI 一般口演 Ｘ線診断III 14:30 〜 15:18 座長 松本 政雄 |
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7. 少数方向の投影データからの３次元血管画像再構成 "Three-dimensional Vascular Image Reconstruction with Few Projections" 梶浦勇生、尾川浩一、国枝悦夫1) 法政大・院・情報電子、慶応大・医・放射1) This paper describes a new image reconstruction method with an MAP-EM method for brain blood vessels. The method uses only a few projections to reconstruct an image. We introduced a new penalty function to the conventional MAP-EM method to keep the connectivity of narrow vessels. The proposed algorithm reconstructs images in two stages. In the first stage a rough estimated image is reconstructed by the MAP-EM method. Then the last image in the first iteration sequence is used for the second penalty function in the second reconstruction sequence. This penalty function can accelerate the convergence of image reconstruction and establish the connectivity of vessels in the MAP-EM method. The validity of the proposed method was confirmed by the simulation with a numerical phantom. |
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8. MDCTにおけるX-ray Beam Trackingによる効果 "Effect of X-ray Beam Tracking in MDCT" 熊崎昌也、西出明彦 GE横河メディカルシステム In MDCT, Xray-beam movement on z-axis and beam penumbra will become a cause of artifact. To accommodate them, beam must be wide enough, but, it will become excessive dose. To solve this, Beam Tracking has enormous contribution to reduce dose up to 40% with good IQ. |
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9. 心電図同期画像再構成法による心臓のＭＤＣＴ ：心室形状評価における動きアーチファクトの影響 "Cardiac MDCT with Retrospective ECG-Gating : Influence of Motion Artifact on Assessment of Ventricular Morphology" 高塀一成、内藤博昭、小縣裕二、山本修司、塚越伸介、濱田星紀1)、 中村仁信1) 阪大院・医・保健、阪大院・医・生情医1)、 We examined influence of motion artifact on assessment of ventricular morphology in cardiac multi-detector raw CT (MDCT) with retrospective ECG-gating. Contrast-medium-filled balloon phantom simulating the left ventricle was scanned at its maximum (end-diastolic: ED) and minimum (end-systolic: ES) static volumes, and under sine-wave contraction in 50 to 80 bpm using Aquilion scanner (Toshiba, Japan). Scan time was 0.5s/rot. Then, the ED / ES CT images of the phantom were displayed with maximum intensity projection (MIP) method. ED and ES volumes were calculated by 2 methods; 1) voxel counting (VC) by setting threshold CT number and 2) Simpson's integration by tracing biplane MIP images (MIP-trace). Axial CT images of the contractile phantom showed arc-like motion artifact.In VC method, ED volume under the contraction was smaller than the static volume and reduced more in higher bpm condition, while ES volume was almost the same as the static volume regardless of bpm. When tracing the contour without blurred boundary in MIP-trace, there showed smaller ED volume andalmost equal ES volume compared with the static ones, these being similar to the results in VC method. In MIP display of the contractile phantom in 50 or70 bpm, wavy boundary was observed even when the images at the same cardiac phase were selected. This study revealed that cardiac motion artifacts cause possible errors in ventricular volumetry and degradation of 3D cardiac images in clinical MDCT. |
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10. 12ビットグレイスケールパターンを用いたＸ線ＣＴ／レーザーイメージャー システムの入出力特性の評価 "Evaluation of input-output characteristic of X-ray CT/laser imager systems using 12bits gray-scale pattern" 浅井義行、中西順子、若江祐子、山口道弘1) 、谷口義則1) 、 前田豊1) 、桜井誠1) 、中平修司2) 、稲邑清也3) 、金森仁志4) 近大・医病・放、府立羽曳野病院・放1)、市立泉佐野病院・放2)、 阪大・医・保健3) 、京都工繊大4) We have attempted to analysis an input-output characteristic of four kinds of X-ray CT （Computed Tomography）systems combined with various laser imagers. An original gray-scale pattern having twelve bits gradations at the CT number range from −3056 to 1024 was used for this measurement. The test pattern was read to hard-disk units of each system, and outputted as X-ray film by using the laser imager. The output film densities of all steps were measured by a densitometer in diffuse density units. The CT numberversus film density curves and the CT number versus gradient value curves were obtained for all CT／laser imager systems. The CT number corresponding to the attenuation of the object is finally changed as the film density according to a LUT ( Look Up Table ) of the CT／laser imager system. As a result, there were noticeable differences among the four kinds of systems with their output values of the film density and the gradient in spite of the same CT number, caused by the property of each LUT. This phenomenon may influence for diagnosis of radiologist. Therefore, the output film density and gradient value should be standardized for all CT／laser imager systems by adjusting the LUT of each laser imager in order to effectuate the accurate diagnosis. |
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VII シンポジウム 15:30 〜 17:30 座長 丸橋 晃、遠藤 真広 「臨床に役立つ医学物理を目指して」 １．放射線治療の立場から 愛知県立がんセンター 内山幸男 ２．放射線診断の立場から 九州大学医療技術短期大学部 東田善治 ３．核医学の立場から 東京都立保健科学大学 篠原広行 ４．放射線防護の立場から 名古屋大学 西澤邦秀 ５．情報システム構築の立場から 北海道大学医療技術短期大学部 渡辺良晴 |
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| 受付開始 ８：１０〜 |
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VIII 一般口演 放射線測定I 8:50 〜 9:26
座長 加藤 二久 |
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11. 診断領域における照射野の線量・線質の不均一性 "Nonuniformity of x-ray intensity and spectra in the diagnostic radiation field" 今川康太郎、宮島悟史、松本政雄1) 阪大院・医・保健、阪大・医・保1) Today x-ray films taken at the clinicofield are indispensable to diagnose diseases exactly and its play a great role in it.Though it is necessary that peoples expect the progress of image qualities of x-ray films,for it some conditions that cause the progress of image qualities must be adjusted.Then,this time we noted one of the characteristic of x-ray diagnostic devices,heel effects.When x-ray is emitted in the diagnostic devices,its finally produces x-ray images through the target. The x-ray are attenuated at the target in the process.Then,when x-ray was emitted,we measured the doses and qualities of a certain field.First,at a distance of 150 cm a field of 60cm*60cm was supposed and in it we measured x-ray dose using ionization chamber and quiality using CdZnTe detector at each points.As a result a big change was confirmed in point of dose,but confirmed along with only the anode-cathode direction in point of quality.So we reports the attenuation effects at the anode,heel effects. |
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12. 大面積アバランシェ光ダイオードの液体キセノンPET検出器としての特性 "Study of LAAPD for detection of scintillation in liquid xenon PET" 月出 章、Vladimir N. Solovov1)、Vitaly Y. Chepel1)、 M Isabel Lopes1)、Rui Ferreira Marques1)、Armando J.P.L. Policarpo1) 高知医大、コインブラ大1) A large area avalanche photodiode, LAAPD, has been tested for its feasibility for the detection of scintillation light in liquid xenon as a basic study of development of gamma detectors for PET and other medical applications. The avalanche photodiode is a device to detect photons from IR to vuv region. The charge gain of several hundred is possible. Recently, the LAAPD became available, the detection area became as large as 200 mm square therefore the possibilities of replacing the conventional photomultiplier in some applications are arisen. In liquid xenon, the photodiode needs to work under severe conditions: it has to operate at temperatures down to ?110 C, withstand vacuum and some external pressure up to about 2 atm. We have immersed a LAAPD in liquid xenon and observed the charge gain and the energy resolution for alpha and gamma radiation. |
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IX 一般口演 放射線測定II 9:26 〜 10:02 座長 西台 武弘 |
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13. 光CTによる陽子線三次元線量分布測定 "Measurement of Proton 3-D Dose Distribution by Light CT" 福田 茂一、佐藤 勝1)、久米 恭、鍵谷 豪、丸橋 晃1) （財）若狭湾エネ研究セ、筑波大・陽子線セ1) The Light CT was designed and developed in order to make the measurement of the proton 3-d dose distribution easy and reliable. It is composed of a scintillation part that emits light according to the proton dose distribution and a CCD camera that can detect the emitted light from arbitrary direction. The principle of Light-CT is basically similar to that of X-ray CT. The proton 3-d dose distribution was reconstructed by the filtered back projection method. The evaluation of its performance was made using the proton radiation field that has four different residual ranges. This demonstrated that Light-CT could measure the proton 3-d dose distribution in use of the principle of the Light CT. However, it also showed some problems such as reduction of resolutions due to the light scattering in the scintillation part. We plan to investigate its effect using the numerical phantom. |
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14. MV領域Ｘ線を用いた治療用線量計校正の実験的検討（II） −電子線用平行平板電離箱の場合 "Experimental Study on Calibration of Reference Dosimeters Using Megavoltage X-ray (II) - Case of parallel plate ionization chamber" 福村明史、平岡 武、石居隆義、竹下美津恵、金井達明 放医研 The Japanese dosimetry protocol for radiation therapy recommends to use ionization chambers, which are caribrated with cobalt-60 gamma ray at a secondary standard dosimetry laboratory (SSDL). However the number of SSDLs which have cobalt-60 gamma-ray source decreases for the last decade. We have examined the possibility to use megavoltage X-ray for the calibration, instead of cobalt-60 gamma ray. As shown in the last JSMP meeting, it turned out that it was possible to calibrate JARP-type thimble ionization chambers in water equivalent phantom with the accuracy of approximately 0.5%. In this presentation, the possibility and the issues for the calibration of parallel plate ionizaiton chambers using the X-ray will be shown from a viewpoint of the result of the actual measurements. |
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15. チェレンコフ光の観察写真における等濃度曲線 "Isodensity Curves based on Photographs of Cherenkov Radiation" 田伏勝義、日比野幸子、松岡祐樹、河井淑裕、長瀬友繁、田宮 正、 八島美穂子、本間光彦、小山修二、小幡康範 名大・医・保健 We have developed the system to observe the Cherenkov radiation in water from secondary electrons generated by Co-60 gamma-rays. Photographs of the Cherenkov radiation from various angles were taken for observation under conditions which consisted of several irradiation fields and pass lengths of gamma-rays in water. The photograph was read by a scanner with Adobe Photoshop and the image was input to a computer for data processing. Further, the image readout from the computer happened to show the isodensity curves of the Cherenkov radiation similar to isodose curves of absorbed dose in water of Co-60 gamma-rays. We, however, should investigate whether or not these curves reflect the absorbed dose in water of Co-60 gamma-rays. If this curve reflects the absorbed doe in water, we can use this method as a imaging method of the absorbed dose distribution based on the Cherenkov radiation. |
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X 一般口演 放射光 14:30 〜 15:18 座長 宇山 親雄 |
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16. 微細石灰化小片の放射光イメージング "Synchrotron Radiation Imaging of Microcalcification Specks" 今村惠子、江原範重、宮本圭子1)、印巻義英、梅谷啓二2)、緒方晴樹1)、 福田 護1)、稲田陽一3)、中島康雄、宇山親雄4)、安藤正海5)、 杉山 弘5)、森 浩一6) 聖マ医大・放、同・乳外1)、JASRI2)、聖マ医大・物理3)、 広島国際大・保健4)、高エ研・物質構造5)、茨城医療大・放6) In an image of a quality control phantom RMI 156, it is usually not easy to fully observe 0.24-mm specks, and the minimum one, 0.16-mm specks, can hardly be recognized with conventional screen/film technique. Using the beamline 20B at the SPring-8, synchrotron radiation images of a wax plate including test objects in it were obtained at various sample-detector distances (SDD) using 20 keV X-ray through monochrometer. CCD camera with a resolution of 24 mm was used as a detector. Non-uniformity of X-ray field was corrected by subtraction. Data was analyzed using an image processing software IPLab. On an absorption image, 0.16-mm specks, as well as 0.24-mm one, were clearly detected. As net signal intensity of a 0.16-mm speck was 10 times of the background noise, smaller specks than that might possibly be detected with this imaging system. Edge enhancement due to refraction became obvious with the increase of SDD. Refraction enhancement was evaluated quantitatively. Comparing with smaller specks, the relative enhancement was 3 times higher for 0.54-mm specks. The enhancement was still on the upward trend at the SDD of 1100 cm for 0.54-mm specks, and those for smaller specks were constant at the shorter SDD, 5 m. As a conclusion, 0.16-mm microcalcification speck was clearly detected with a SNR of 10, and refraction enhancement was higher for images of larger specks obtained at larger sample-detector distances. |
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17. ２焦点蛍光Ｘ線源による単色Ｘ線ステレオ撮影 "Monochromatic X-Ray Stereoscopic Imaging Using Double-Focus Fluorescent X-Ray Sources" 豊福不可依、徳森謙二1)、東田善治、大喜雅文、兵藤一行2)、 安藤正海2)、宇山親雄3) 九大・医短・診放、九大院・歯・病態・画像情報1)、高エ研・物構研2)、 広国大・保医・臨工3) A double-focus fluorescent x-ray source for stereoscopic imaging has been developed using a 6.5 GeV synchrotron radiation storage ring at Tsukuba (Japan). The fluorescent x-ray source is composed of a cylindrical rotating target holder of 25mm in diameter on which a pair of metal target strips are attached at a distance of 2mm apart. At each time the incident white x-ray beam from the bending magnet, collimated to 1mm x 1mm, irradiates a pair of target materials, fluorescent x-rays of two different energy photons are generated at time intervals of 10ms at the rotation rate of 120 rpm. Fluorescent x-rays, which range from about 20 keV to 75 keV can be generated by changing the target materials. In case of iodine contrast medium, fluorescent x-rays from Ba and Ce, having 32.2 and 34.7 keV K x-ray energies respectively, can be used for K-edge subtraction of iodine which has K absorption edge of 33.17 keV. Stereoscopic fluoroscopy has been performed either by using only one image intensifier(single I.I. mode), or by using two image intensifiers(double I.I. mode). |
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18. 蛍光Ｘ線源を用いた単色Ｘ線ＣＴ装置の定量評価装置（II） "Analysis of Linear Attenuation Coefficients Obtained from Monochromatic X-ray CT Using Fluorescent X-Rays" 徳森謙二、豊福不可依1) 、神田重信、兵藤一行2) 、安藤正海2) 、 宇山親雄3) 九大院・歯・病態・画像情報、九大・医短・診放1) 、 高エ研・物構研2) 、広国大・保医・臨工3) This study was undertaken to develop a monochromatic x-ray CT system using fluorescent x-rays excited by synchrotron radiation and to investigate its characteristics. The system consists of a fluorescent x-ray source, a CdTe array detector, a rotational pulse stage and a controller. The fluorescent x-ray source had two materials; one was the target material that was excited by white x-rays generated by synchrotron radiation and the other was a filter material to reduce Kβ x-rays. The CdTe array detector had 256 CdTe elements. Because the size of an element was 1.98 mm(w) × 1.98 mm(h) × 0.5 mm(t) and the space between the elements was 0.02, the total sensitive area was 512mm. In order to evaluate the accuracy of the linear attenuation coefficeints, a cylindrical Lucite phantom containing gadolinium (Gd) contrast medium with different concentrations was used. The CT numbers obtained from CT images of the phantom were compared with theoretical linear attenuation coefficients, and they showed a good agreement within 5% over a wide range of Gd concentrations. Monochromatic x-ray CT images of a cylindrical phantom were obtained at the energies above and below Gd K-edge. By taking subtraction, Gd image was obtained. From the subtraction image, the smallest possible detectable quantity was about 1% gadolinium concentration, however, by using the suitable monochromatic x-ray energies, it should be possible to reduce this limit. |
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19. 佐賀シンクロトロン光応用研究施設とその医学利用の検討 "Study on Medical Applications of Saga Synchrotron Light Applications Research Facility" 豊福不可依、徳森謙二1) 、東田善治、大喜雅文、兵藤一行2) 、 安藤正海2) 、松本政雄3) 、宇山親雄4) 九大・医短・診放、九大院・歯・病態・画像情報1) 、高エ研・物構研2) 、 阪大・医・保健3) 、広国大・保医・臨工4) The Saga Synchrotron Light Applications Research Facility (Saga SL), which is presently under construction, to be completed in 2003, will be the only synchrotron radiation facility established by a local government body (Saga prefecture) in Japan. The facility will have an electron storage ring which will operate at an energy of 1.4 GeV. It will have a total of 20 beam lines, including a 7.5 T superconducting wiggler beamline which will produce x-rays of 1-30 keV. The brightness of x-rays from the wiggler beam line is estimated to be about 10^12 photons/sec/mrad^2/0.1%BW at 25 keV. There are, at present, eleven research working groups, one of which is the biomedical science research group. Our group has investigated the possible applications of this synchrotron light source for biological and medical uses, such as monochromatic x-ray mammography, monochromatic x-ray CT, phase contrast imaging and so forth. The internet web site of Saga SL is http://www.infosaga.or.jp/synchrotron/saga_sl_plan_en.html (or http://www.infosaga.or.jp/synchrotron/index.htm). |
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XI 一般口演 放射線治療I 8:50 〜 9:50 座長 中村 譲 |
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20. コンボルーション法で用いる一次及び散乱線量拡散分布に関する考察 "Comments on the primary and scatter dose-spread kernels used for convolution methods" 岩崎 晃 弘前大・医 The basic primary and scatter dose-spread kernels used for convolution methods are usually produced by Monte Carlo simulations with the interaction point forced to the center of a large water phantom. However, it is still not clear whether such Monte Carlo based kernels allow accurate dose calculations with a wide range of field sizes and depths, especially in thorax phantoms. This paper proposes another type of basic kernel, with which perfectly accurate primary and scatter absorbed dose calculations can be performed under certain irradiation conditions. |
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21. 微分一次及び散乱線量法を用いての胸部ファントム内での10MVエックス線ビーム軸線量の計算 "10 MV X-ray beam-axis dose calculation in thorax phantoms using the differential primary and scatter method" 岩崎 晃、久保田 護 弘前大・医 The differential primary and scatter method (based on convolution) was used for calculating 10 MV X-ray primary and scatter doses on the beam axis in water-cork-water layered phantoms (simulating thoraxes), including the contaminant electron dose. The in-water primary and scatter dose-spread kernels were constructed based on the zero-area TMR (tissue-maximum ratio) and the LSD (laterally spread primary dose), and the SMR (scatter-maximum ratio), respectively. This method can, in general, produce accurate estimates of dose even in regions under longitudinal and/or lateral electronic disequilibria. |
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22. CRシステムによる線量分布測定法 "A Method for Measuring the Dose Distribution using the Computed Radiography System" 本間光彦、田伏勝義、小幡康範、田宮 正、小山修司、石垣武男1) 名大・医・保健、名大・医・医1) Grasp of a dose distribution in a tissue is very important as well as measurement of an exposure dose or the absorbed dose in radiotherapy. Then, we have developed a measurement method(CR method) of the dose distribution in the phantom based on the imaging plate(IP) of the computed radiography(CR). The IP was applied for the dose measurement as a dosimeter instead of a film used for the film dosimeter. The data from the irradiated IP were processed by a personal computer with 10 Bits and were depicted as absorbed dose distributions in the phantom. The image of the dose distribution was obtained from the CR system using the DICOM form. The CR method is application of CR system currently used for medical examination to dosimetry in radiotherapy. A dose distribution can be easily shown by our dose distribution depiction system developed this time. Moreover, the measurement method is very simple and a result is immediately obtained compared with the film method. |
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23. フィルム法による高エネルギー放射線線量分布測定時の光の影響 "Contribution of light in high-energy film dosimetry using water phantoms" 藤崎達也、平岡 武1)、 齋藤秀敏2)、桑原秋夫3)、村石 浩、 阿部慎司、西村克之、稲田哲雄、 茨城医療大、放医研1)、都保健大2)、癌研病院3) The contribution of light in high-energy film dosimetry was examined using commercially available water phantoms. It is difficult to evaluate the relative and absolute doses using these phantoms with unpacked film due to the contribution of light. The contribution of light was esti-mated based on the difference in the dose measurement with the shielded for shutting off the light and unshielded sides on a phantom. The presence of Cerenkov radiation increased in appearance the dose of the unshielded side up to 68% for 10 MV X-ray and 82% for 18 MeV electron beam compared to the actual dose of the shielded side. The results suggest that the use of several phantoms may improve the accuracy of dose distribution measurements in film dosimetry. |
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24. 高エネルギーＸ線・電子線がペースメーカに及ぼす影響 "Interference of high energy X-ray and Electron beam to the function of the Pacemaker" 川村慎二、久家教幸、小野誠司1)、柴 徹1)、廣瀬哲雄 宮崎医大附病院・放射線部、宮崎医大附病院・放射線科1) Miniaturization and function enhancement of permanent pacemaker always advances, and the number of pacemaker implanted patient gradually increased in these years. The radiation Interference for a pacemaker is variously reported. However, the safety guideline for the radiation has not been specified. In this time, the direct irradiation was carried out using five new pacemaker of programmable demand type taking the 3 micron rule of IC. The Interference was analized in the parts of a lead wire, a battery and a electronic circuit. Electromagnetic interference and effect for the battery could not be recognized. The interference to the electronic circuit was caused from start to end of the irradiation. In the irradiation dose of 9〜42Gy, the permanent failure of the output voltage was occured in three pacemakers. As a result, the interference of the pacemaker caused in the dysfunction of the electronic circuit, then further study was required in the field of the interference between pacemaker and irradiation. |
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XII 一般口演 放射線治療II 9:50 〜 10:38 座長 川越 康充 |
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25. 補償フィルタによる高速IMRTの検討 "An Approach to Fast IMRT using compensator" 依田 潔、青木幸昌1) 三菱電機・先端総研、東大病院・放射1) An approach to fast IMRT using compensator has been proposed, where a compensator is semi-automatically produced by a thermoplastic sheet and motor-driven position controller having 10x10 rod elements. The thermoplastic sheet is heated by a planar heater, and subsequently the position controller adjusts each rod height according to calculated intensity profiles for IMRT. After cooling down the sheet, heavy metal particles are fed into the compensator and up to 6 compensators are positioned at the linac head attachment. The attachment rotates like a revolver by electric control signals, thus allowing automatic multi-portal IMRT without using multileaf collimator (MLC). We expect that (1) IMRT irradiation time will be reduced to 2 minutes similar to conventional radiotherapy, thereby minimizing patient body fixation issue; (2) target dose distribution will be relatively uniform compared to MLC-based IMRT; and (3) patient throughput will be superior. |
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26. 定位放射線治療の頭部内基準点について "A study of base point in the skull in stereotactic radiotherapy" 隅 真一郎、入船寅二、国枝悦夫1)、大谷浩樹 都保健大、慶応大・放1) Stereotactic radiotherapy is required to irradiate a small tumor accurately. It is performed according to treatment planning that is established by the outside bass point of head. However, the fractionated irradiation method has a problem of accuracy for the outside base point compared with single portal irradiation. The purpose of this study is standardization of base point in the skull for stereotactic irradiation. Some base points in the skull were assumed by a head phantom on an anatomical feature. Linac grapy with anterior direction and lateral direction were taken. We examined accuracy of a base point in the skull. Clinical application was performed used a base point for stereotactic radiotherapy. I was able to set some good base points of accuracy in the skull. Irradiation method was confirmed by linac grapy just before a therapy. It was suggested that the base point in the skull on thus study were useful for improvement of stereotactic radiotherapy. |
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27. プログラミング言語Javaを使用したモンテカルロシミュレーション "Monte Carlo Simulation using Programing Language Java" 木下克之、山本時裕、手島昭樹、村瀬研也 阪大・医・保健 Introduction: The Monte Carlo simulation is numerical experimental method that can faithfully reproduce the radiation transport process in the compute r. Especially, Monte Carlo method is useful for the case in which experiment s are difficult, analysis of the experimental result and case in which the d ata is wanted before the experiment. Then, we do Monte Carlo of initial beam data for photons using programing language Java. Methods: Physical process es of being necessary for Monte Carlo in radiation transport are the followi ng: Bremsstrahlung production, Positron annihilation in flight and at rest, Moliere multiple scattering, Moller and Bhabha scattering, Continuous energy loss, Pair production, Compton scattering, Coherent scattering and Photoele ctric effect. Then, these physical processes are classified into component ( class), and the function of each component is defined. Next, component of th e initial beam data for photons is programed, and the sampling is carried ou t. Results : Each component were defined, and the initial beam data for pho tons was sampled. Discussion: By the component, complicated sampling proces ses of the radiation transport and maintenance of each data would be possibl e. However, it is necessary to do further development for the accurate Monte Carlo simulation of radiation transport. |
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28. CT画像を利用したモンテカルロ治療計画システムの開発 "Development of Monte Carlo Radiotherapy Planning System Using CT Data" 遠山尚紀、齋藤秀敏、白砂吉隆、坂井涼子1)、藤崎達也2) 都保健大、メディカル・フロント1)、茨城県医療大2) Stereotactic irradiation using a linear accelerator has come to be considered an effective means of lung cancer, and has been widely adopted in many hospitals recently. For this radiotherapy technique, accurate dosimetry is important for determining the absorbed dose to target volume. Nevertheless, there are some difficulties caused by a smaller field than conventional techniques and anatomical complexity. For instance, the density of lung is smaller than that of soft tissue, the number of recoil electron per unit volume is smaller than that of soft tissue and the recoil electron travels longer distance and may arrive outside of the field. Therefore, it is necessary to develop radiotherapy treatment planning system which can simulate electron transport. The development of novel radiotherapy treatment planning system which adapt Monte Carlo method as dose calculation algorithm and which deal with multi port static and moving therapy is in progress. In the report, the conception and design will be described. |
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XIII 一般口演 放射線治療V 10:46 〜 11:22 座長 秋山 芳久 |
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29. インターネット上での施設既存データベースからROGADへのデータインポートシステム "A system for data import from existed databases in each facility to internet based ROGAD" 熊崎 祐、原内 一1)、国府裕子、近藤誉史、石橋正敏、沼崎穂高、 清水敬二1)、佐藤理恵子1)、梅田徳男2)、武村哲治3) 、稲邑清也1) 阪大院・医・保健、阪大・医・保健1)、北里大・衛生2)、 金沢大・医・保健3) One of data collection methods of ROGAD(Radiation Oncology Greater Area Database)is to import data from existed radiotherapy database in each facility according to the original protocol of ROGAD. The data manager of ROGAD office must convert data with protocol of an existed database at the facility into data with ROGAD protocol. So, off-line conversion programs were developed and have been used. However, labor to generate these conversion tables for data conversion is hard. Accordingly, in order to shorten time for a data link and to improve data link efficiency, an automatic on-line data import system for ROGAD has been developed. The system is applicable to existed databases of different protocol and different application softwares. By employing our developed system, improvement in speed, quitting of floppy disk mailing and labor saving in both ROGAD side and facility side were realized. Because we discussed a conversion table beforehand with those who has been conventionally engaged in ROGAD jobs in facilities and generated the conversion tables, the necessity of manual conversion jobs disappeared by generating it automatically at a facility side PC. In this study, jobs of conversion table generation were functionally simplified. But it still needs improvement in semantic contents check by an oncologist in charge and syntactic check by automatic software in order to maintain the complete accuracy of ROGAD. |
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30. インターネットを利用したROGADにおけるエージェント指向型機能の開発 "Development of the Agent-Oriented Data Check Function in Radiation Oncology Greater Area Database Using the Internet" 石橋正敏、原内 一1)、近藤誉史、熊崎 祐、国府裕子、沼崎穂高、 清水敬二1)、佐藤理恵子1)、梅田徳男2)、武村哲治3) 、稲邑清也1) 阪大院・医・保健、阪大・医・保健1)、北里大・衛生2)、 金沢大・医・保健3) An agent-oriented data check is used as our strategy to reduce an incorrect input and to enhance accuracy of radiotherapy database. The incorrect data entry which causes inaccuracy of a radiotherapy database happens by carelessness, by wrong decision making and by change of meaning with elapse of time. Decrease of this incorrect input leads to improvement of utility value of a database. １.The logical check, which was carried out to prevent the careless mistake, was simultaneously performed automatically with the on-line entry of the contents. Namely the function which enables the agent-oriented data check and corrects the inputted wrong value to the right value, was developed. ２. When primary tumor region code, pathology code and UICC stage code were entered for a patient, the current data of this patient in the database was accessed, and the corresponding codes were extracted and compared. The function which supports presentation and packaged entry were added. By our method, examination of data accuracy was supported and the time for registration could be saved and the exact entry was completed by this function. This function performed the logical check to all registered items, and the reliability of saved data was improved. |
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31. オンラインでのROGAD症例登録におけるデータ精度維持システム "The system for accuracy maintenance of clinical regist ration record for on-line ROGAD." 近藤誉史、原内 一1)、石橋正敏、熊崎 祐、沼崎穂高、国府裕子、 清水敬二1)、佐藤理恵子1)、梅田徳男2)、武村哲治3) 、稲邑清也1) 阪大院・医・保健、阪大・医・保健1)、北里大・衛生2)、 金沢大・医・保健3) For ROGAD ( Radiation Oncology Greater Area Database ) aiming at grasp of real situation of radiotherapy in whole Japan, on-line data registration method is being constructed. In case registration to ROGAD is carried out by using a public telephone line, problems such as high cost and increase of operating time due to slow transmission speed will occur. For this reason, it is difficult to repeat reentries of data. Consequently registered data may not be corrected. Besides, such misregistration would occur much more frequently when a series of radiotherapy is interrupted or discontinued. Therefore, the new method, which maintains the accuracy of the data of ROGAD, is needed. One of solutions is to give ROGAD verification function between treatment planning data and treatment record. From now on, our developed function which examines coincidence of data in existing dose verification system in each institution with registered data in ROGAD can be added. |
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XIV 一般口演 粒子線治療I 11:22 〜 12:10 座長 古林 徹 |
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32. 放射線治療計画のための呼吸同期CT装置 "Respiration gated CT for Treatment planning" 綱島義一、石川達子榮武二、佐藤勝、塩山善之、照沼利之、納冨昭弘、 丸橋 晃 筑波大・陽子線セ In Proton Medical Research Center(PMRC),we had performed respiration gated irradiation for body treatment. For the treatment planning, CT scanning is performed by means of making patient expiratory holding. On the other hand, for the sake of high accurate irradiation in the new facility, we introduce the respiration gated CT scanning system. As presented at JSMP81, the stable period of subject's(patient's) end-expiratory is not so long as CT scanning time(1 seconds) in PMRC. So the motion artifact appears in the image and it is impossible to use respiration gated CT scanning up to this time. In this study, we developed a guided respiration system that allows a subject to expand end-expiratory phase. Respiration gated CT scanning are performed by using this system. |
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33. ２重散乱体と加速器によるエネルギースキャンを用いた陽子線照射系の概念設計 "Conceptual design of fixed-modulation proton beam delivery system using double scatterer and energy scanning" 高田義久、平野真雄、松本圭司、河野良介 筑波大・物工 We propose a fixed-modulation proton beam delivery system using double scatterer and energy scanning by accelerator. The SOBP(Spread-Out Bragg Peak) is formed by adjusting proton fluences for individual energies comprising the SOBP. The beam energies are varied stepwise by accelerator. Since the scattering in the double scattering system depends on the beam energies, the scatterer parameters are adjusted to keep the similarity of the lateral distributions of the individual energies. For that purpose, thickness of the 1st scatterer and the longitudinal position of the dual-ring second scatterer are changed to keep the similarity of the lateral distributions. It is shown that this scheme works well. For proton beam with energy more than 200 MeV, more than 8 cm SOBP width can be covered by a single piece of dual-ring. In lower energy region, SOBP width covered by a single piece of dual-ring decreases. If we need larger SOBP width, we change the piece of the dual-ring to another one optimized for lower energy by rotating a table mounting eleven different pieces of dual-rings. This method will improve the distal and lateral penumbra of dose distribution. |
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34. 不均質媒質中の陽子線・線量分布に関する基礎研究 "Basic Studies for Proton Dose Distributions in Heterogeneities" 河野良介、高田義久、榮 武二1)、照沼利之2)、松本圭司、納冨昭弘、 松田博之 筑波大・物工、筑波大・臨医1)、PMRC2) We have already developed a method of dose calculation based on the pencil beam algorithm (PBA) and verified the usefulness of the PBA by the comparison between the results of the PBA in water and measurements using a simple L-shaped phantom. We study here applicability of the PBA by applying it to more complex phantom. The calculation results using the PBA often might not agree with the measurement results for large heterogeneities such as lung cancer due to the error of proton beam spread calculation by applying the water-equivalent model to lung or the edge scattering effects. We manufactured heterogeneous phantoms which were made of Tough Water and Tough Lung, and verified the accuracy of the PBA by the measurements results of dose distributions in their heterogeneities. In addition, dose distributions by the modified pencil beam algorithm (MPBA) which calculates the spread of proton beam due to multiple scattering effect in individual materials correctly and by the Monte Carlo method (MC) were also calculated. As a result, the calculated results by the PBA agreed well with the measured dose distributions within several percent Since the PBA could not predict the edge scattering effect, as we had expected. The MPBA somewhat improved the accuracy. The calculated results by the MC agreed considerably with the measured ones. |
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35. 医療用陽子ビーム輸送系のビーム軌道補正の研究 "Study of central orbit correction for medical proton beam transport system" 松田博之、高田義久、照沼利之1)、河野良介、松本圭司 筑波大・物工、PMRC1) New proton facility which equips a 250 MeV synchrotron and two rotating gantries was constructed recently. Several mangets, like quadrupole, bending, steering magnets, have been installed in the beam delivery system. The new facility adopt a double scattering method in order to obtain a laterally-uniform distribution. Therefore central beam orbit must accurately pass center of a double scatter. If the central beam orbit deviates much from the center, we need to correct it by steering magnets installed in the beam delivery system. Closed orbit distortion(COD) is caused by alignment errors of magnets and setting errors of magnet current etc. We analyze the COD using the transfer matrix for beam line. We will report the method of COD correction by steering magnets. We measured the beam misalignment dependent on the gantry angle. |
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XV 一般口演 粒子線治療II 13:30 〜 14:18 座長 丸橋 晃 |
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36. 回転ガントリー用ビーム調整の再現性と最適化 "Reproduction and Optimization of Beam Tuning for Rotating Gantry" 東 明男、赤城 卓、板野明史、伊佐英範1)、錦郡和人1)、本多保男1)、 福島修三2)、藤田 厚2)、香川武志2) 兵庫県立粒子線セ、加速器エンジニアリング1)、三菱電機2) Clinical trial of proton therapy part started at 22-MAY-2001 in HIBMC. It is important to accurate and rapid beam tuning for rotating gantry because flat irradiation field and increasing patient number. In HARIMAC, all of scheduled beam are tuned in early morning to isocenter inside of irradiation room and memorized on control system. In daytime, before needs of beam for treatments or measurements, beam is verified upstream the irradiation rooms using parameter tuned in early morning. It takes about 2 minuets to verify and intensity and flatness are stable. Above methods are capable in clinical trial because patient number is small. But, it is necessary to easier of beam tuning in the early morning in general use for particle therapy. Data for reproduction of beam axis upstream and inside of irradiation room suggest beam is to be tuned just before needs and tuned upstream the room. We studied additional way that optimization of parameter files to decrease deviation of beam axis for gantry rotation. It can make easy and rapid beam tuning in early morning. Anyway, data acquisition is necessary and now performing for reproduction of beam axis in gantry. |
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37. 粒子線の照射野形成 "Radiation Field Formation for charged Paritcle Radiotherapy" 赤城 卓、舛田泰隆1)、津上浩伸2) 兵庫県立粒子線セ、加速器エンジニアリング1)、三菱電機2) Hyogo Ion Beam Medical Centre for Charged Particle Radiotherapy has four fixed beam ports for proton and carbon, and two rotating gantries for proton. Wobbler beam delivery system and ridge filter are applied for forming large radiation fields. Since charged particle is scattered by the ridge filter, the effect of the scattering should be considered in the field formation. The procedure will be reported. As the result, +-2.5% of uniformity was accomplished. |
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38. 若狭湾エネルギー研究センターにおける陽子線がん治療研究開始準備状況 "Present Status of Proton Therapy Project at Wakasa-Wan Energy Research Center" 久米 恭、福田 茂一、福本 貞義、山本 和高、丸山 市郎、鍵谷 豪、 横濱 則也、長谷川 崇 若狭湾エネ研究セ Present status of the proton therapy project at WERC(Wakasa-Wan Energy Research Center) is reported. After the construction of accelarators including the 200MeV proton synchrotron, the beam line for the medical use has been constructed until August 2001. Accelarators are consisted of an negative charge ion source, 5MV Tandem, and 200MeV proton synchrotron, which can deliver 10nA proton beam as a maximum current at 200MeV. Proton energy is tunable between 80MeV and 200MeV by 7 steps. Medical beam line has been constructed to produce maximum irradiation field of 100mm radius x 100mm depth by using Wobbler magnets and scatterers. Ridge filters, boluses and collimators are now being examined. Patient positioning is planned, to use X-ray CT at every irradiation, with using of DR supplementry. Treatment planning system, which will calculate the dose distribution by broad beam algorythm and decide the shape of boluses and collimators, are now being examined. The system is developed by Hitachi. This therapy project is planned to be started as soon as possible after various checks have been done. |
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39. ブロードビーム重イオンCTの性能評価‐1 "Performance of Broad Beam Heavy Ion CT -1" 大野由美子、河野俊之、松藤成弘1)、金井達明1)、浦壁恵理子1) 東工大・総合理工、放医研・重粒子1) In order to achieve the radiotherapy more precisely using highly energetic heavy charged particles, it is important to know the distribution of the electron density in a human body, which is highly related to the range of charged particles. In a current treatment planning, the CT number from an X-ray CT image is converted into the corresponding electron density. Although some conversion methods have been proposed, a slight disagreement exists among them. On the other hand, we can directly obtain the 2-D distribution of the electron density in a sample from a heavy ion CT image. The direct measurement of the electron density of real tissue-equivalent samples using this system will make it possible to adjust the relationship between the CT number and the electron density. We have already established a heavy ion CT using a pencil beam scanning method. As an extension of this method, a detector system for a broad beam was developed to decrease the total amount of dose and to shorten the measuring time. In the experiments, the projection data of a phantom was obtained and its CT image was reconstructed. As a result, the measuring time was shortened from 120 minutes to 5 minutes, keeping the spatial resolution of 1.6 mm, which is equal to that using the previous method. |
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XVI 特別講演 14:30 〜 15:20 座長 稲邑 清也 外科手術と情報科学 大阪大学 越智 隆弘 |
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XVII 一般口演 画像処理・表示I 15:30 〜 16:18 座長 藤田 広志 |
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40. Javaによる医療画像自動連続表示解析システムの構築 "Design of the System of Automatic Consecutive Display of Medical Images and Image Analysis by Java" 後藤洋平、田中亨、外田稔1)、鈴木茂人 北見工大、市立札幌病院1) A large number of tomographic images has recently been taken for a patient; the number of slice images is often over 100. This eminent increase in the number of tomographic images for a patient causes a increasing burden for radiologists. The situation will require a reconsideration of a conventional manner of image diagnosis and a technical improvement in image diagnosis work using a computer-aided diagnosis system. A computer software system is proposed in the present study to reduce a burden for radiologists in image diagnosis work. This system, which is made by using Java language, consists of two major functions: automatic consecutive display of medical images and image analysis. The first function will be useful in diagnosing a large number of images and effective in reducing diagnosis work. The second function will provide advantageous diagnostic information to assist a diagnosis. The present system uses Java language because this language can be applicable to different operating systems such as Windows and Unix. To see the effectiveness of the system, it is applied to MRI images which consist of 80 slices of size 512 x 512 and gray level 8 bits. The proposed system shows good performance although there are several points to be improved. |
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41. マンモグラフィファントム画像の画質評価のための自動計測 "Automatic Measurement of Phantom Image Quality for Mammography Quality Control" 江原範重、依光和夫1)、今村惠子、大内憲明2)、中島康雄 聖マリアンナ医大・放、（株）ソリューションシステムズ1)、 東北大・腫瘍外2) In order to improve the efficiency of image quality evaluation, we coded a script of image processing software "IPLab for Macintosh" to automate ROI settings on test objects and pixel value measurement in images of mammographic phantom RMI 156 after digitization. To determine locations of ROIs, the origin of coordinate was set at the left upper corner of a rectangular wax plate image in phantom manually in the running script, then 33 ROIs were positioned automatically on target test objects and film base. If a ROI was not set satisfactory, we could re-position the origin and/or individual ROIs without changing script code. Initial setting of ROIs was correct with only minor adjustment when the phantoms had the same lot number and when the wax plate edge of the phantom was parallel to digitized image edge, because relative pixel positions among the origin and testing objects were virtually the same in images. When the wax plate image on the film was rotated to the film edge, it was necessary to re-position considerable numbers of ROIs because we could not use trigonometric functions in the script to rotate ROIs positions and it was not desirable to rotate the image arithmetically. As the next step, it seems that we need to refine the functions of the script to reduce the chance of re-positioning of ROIs, and need to examine rotating method of ROIs positions without trigonometric calculations in the script. |
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42. 統計的手法を用いたDSA用マスク画像の抽出 "Extraction of Mask Images for DSA with a Statistical Method" 乳井嘉之、尾川浩一1)2)、國枝悦夫2) 都立保健大・放射、法政大・工・電子情報1)、慶応大・医学・放射2) DSA (digital subtraction angiography) is a technique to visualize blood vessels from sequentially acquired images with the contrast medium. The mask image which is used for subtracting a background structure is very important to keep the quality of DSA images. This mask image is commonly selected arbitrarily, thus DSA images are sometimes degraded by the mask image. The paper proposes a new method to make an optimum mask image from a series of acquired raw data. To make this mask image we used a principal component analysis and we adopted the first component image as this mask image. Obtained results with actual images showed the effectivity of the proposed method. |
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43. SPECT画像再構成における前処理付き共役勾配法 "Preconditioned Conjugate Gradient Algorithm for SPECT Image Reconstruction" 守田和就、後藤洋平、鈴木茂人 北見工大 The conjugate gradient method, which is used to solve nonlinear optimization problems, has been applied to SPECT image reconstruction and a number of attempts to speed up the convergence has been made. Preconditioned conjugate gradient methods with various preconditioning matrices (or preconditioiners) have been proposed to accelerate the convergence rate of the conjugate gradient method. The purpose of the present study is to make a comparative study on preconditioiners which have already been proposed in order to see their properties and effectiveness. The study will lead to a new proposal of preconditioiner. Preconditioiners used pixel values, detection probabilities of gamma rays and Hessian matrices are considered in the present work. Image reconstruction is performed for two cases with and without statistical noise in the projection data using two mathematical phantoms such as the Shepp-Logan. The objective function in the present work includes the penalty function for suppressing image noise due to the statistical noise. The preconditioners were effective in enhancing convergence rates with a few exceptions. Some preconditioiners such as the Hessian matrix preconditioiner showed a strong dependence on initial image pixel values, thereby the exceptions were produced. The preconditioiner used pixel values were superior in speeding up convergence in the present reconstruction situation. |
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XVIII 一般口演 画像処理・表示II 16:18 〜 17:06 座長 西村 克之 |
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44 CT画像のノイズ除去と被曝線量の低減 "Denoising of CT images and reduction of patient's dose" 中森伸行、楊 義強、吉田靖夫 京都工繊大・電子情報 The multi-slice CT (Computed Tomography) and cone-beam CT can obtain a patient's 3-D image in a short time, compared with conventional CT. On the other hand, the radiation dose to the patient increases. When the radiation dose to the patient is reduced, quantum mottle in projection data increases. And the quality of image gets worse, then an accuracy of medical diagnostic decreases. We have studied the reduction of noise in CT image using the wavelet transform maximum-coefficient method (WTMM: Wavelet Transform Modulus Maxima). The WTMM technique is an algorithm, which analyzes the characteristic feature of the coefficient of the wavelet transform of a signal and a noise, and removes only a noise. Using the head phantom of Shepp-Logan, noise that is statistically described by Poisson probability function, is added in projection data. And we have examined the effect of a noise-reduction, using WTMM method. Our preliminary results show that it is possible to reduce the radiation dose to 1/10, with the image quality maintained. |
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45. X線CTにおける金属アーチファクト低減手法の評価 "Evaluation of A Method for X-Ray CT Metal Artifact Reduction" 岩元新一郎、山嵜洋一（1）、篠原雅昭（1）、飯沼雅博（1）、川 真田 実（2）、 永吉 誠（2）、村瀬研也（2）) 大阪物療、阪大院・医・保健1)、阪大・医・保健2) In medical X-ray CT equipments, the degradation of image quality due to metal artifacts is a serious problem for clinical diagnosis. The iterative reconstruction reprojection (IRR) method has generally been used for reducing metal artifacts. This method reprojects the image reconstructed using the filtered back-projection (FBP) method. Then, a certain correction is added to the projection data, and image reconstruction is again performed using the FBP method. However, the reduction of artifacts from an object such as a metal denture using this method is not always satisfactory. In this study, we applied the expectation-maximization (EM) method combined with the IRR method to clinical data and evaluated its usefulness for reducing metal artifacts. We found that this method can reduce intense metal artifacts effectively and is helpful for clinical diagnosis. |
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46. 逐次近似法による重粒子線CTの画像再構成 "Iterative Image Reconstruction for Heavy Ion CT" 村石 浩、西村克之、小田千鶴、富田哲也、阿部慎司、佐藤 斉、藤崎達也、 稲田哲雄、田沢修一、金井達明1)、河内清光2) 茨城県立医療大、放医研1)、原安技術セ2) We report on the results of the first application of the iterative image reconstraction with the simultaneous reconstruction technique for the heavy ion CT data with phantoms which was taken by the heavy ion CT system with fluoroscopy detector and range shifter using a 12C beam with energy of 400MeV/u accelerated by HIMAC. It is shown that the artifact noise is decreased on the iterative reconstruction image compared with the image with the filter back projection method. Our results suggest the importance of iterative reconstruction method for heavy ion CT. The application of new iterative algorisum as OS-EM developing in the X-ray CT or Nuclear Medicine will be expected in the future. |
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47. 飛程分布測定による重粒子線CTのサイノグラム作成 "Sinogram for Heavy Ion CT by Measurement of Residual Range Distribution" 富田哲也、西村克之、阿部慎司、佐藤斉、稲田哲雄、田澤修一、金井達明1)、 河内清光2) 茨城県立医療大、放医研1)、原安技術セ2) The heavy ion CT system in our study utilizes the measurement of the residual range distribution. In the preprocess performed before the reconstruction, the sinogram should be made. The sinogram is formed from the set of projection data corresponding to the set of thickness of range shifter. A phantom was used for the evaluation of the system, which was immersed in water and contained the 6 rods that were different in density. We propose the improved method for making the sinogram to have a reconstructed image better than previously reported one. The images reconstructed with the proposed method and previous one were compared. It was found that the noise characteristics were drastically improved while the density resolution remained comparable to previous method. |
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XIX 一般口演 画像処理・表示III・医療情報・画像管理システム 17:06 〜 17:42 座長 梅田 徳男 |
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48. 遺伝的アルゴリズムを用いたMRI画像の領域予測符号化 "Region-Based Prediction Coding for MRI image Using Genetic Algorithm" 越野一博、外田稔1)、鈴木茂人 北見工大、市立札幌病院1) The purpose of this paper is to compress MRI images efficiently by a region-based prediction coding using the genetic algorithm. The prediction consists of five transforms: two translations and two scaling for horizontal and vertical directions, and one rotation. It searches five transforms which minimize prediction errors, but it takes a long time to obtain a mathematically optimum solution. For making a fast search the proposed method uses the genetic algorithm by which an approximate solution can be obtained. In addition, for achieving high compression performance the method uses the region-based coding. The region-based coding is based on the assumption that there is a correlation between the current image and the immediately neighboring images. An MRI image of size 512 x 512 and of gray scale 8 bits per pixel is compressed by the proposed region-based coding; a PSNR of 33.7dB and a compression ratio of 91:1 are obtained. The compression ratio is higher by a factor of six than that obtained by the non region-based coding although the PSNR is lower than that of the non region-based coding by 1%. Furthermore, the processing time by the proposed coding is 69 % of that by the non region-based coding. |
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49. 医療スタッフのワークフロー分析のための時間因子と行動内容による業務分類法 "Methodology development of job classification by using time factor and behavior factor for workflow analysis of medical staff" 沼崎穂高、原内 一1)、大倉保彦、石井豊恵、笠原聡子1)、門田守人2)、 左近賢人2)、坂東昌子３)、大野ゆう子1)、稲邑清也1) 阪大院・医・保健、阪大・医・保健1)、阪大・医・第２外2)、 阪大医附属病・看護３) We are performing time study of the medical staff's behavior along their workflow in Osaka University Hospital. It has been continuing since 1998. It aims at developing a new job classification system for workflow analysis of medical staff required for modeling of job frequency distribution characteristics. In order to perform the model simulation for examining the medical staff's job efficiency three-layered structure (it consists of job category, job classification and branched job) paying attention to medical staff’s behavior, action and purpose was formed. And measured data according to the three-layered structure were plotted as a job frequency histogram per hour in a day. Job frequency distribution was divided into six patterns by examining and comparing the characteristics obtained from the histogram of job frequency. Furthermore, jobs were sorted out into four modes in terms of the mean time required. And they were also split into two parts by the size of standard deviation which is influenced by ability of a medical staff and job environment. Finally the medical staff's jobs were able to be expressed by mathematical formula with grouping of (6×4×2) characteristics. As a conclusion, methodology of job classification which takes account of difference of environment of each hospital or a ward is possible to be developed. |
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50. 放射線治療におけるオンライン精度管理システムの構築 "On-Line Quality Assurance System of Radiotherapy" 飯沼正博、手島昭樹1)、篠原雅昭、山嵜洋一、岩永弓紀1)、河上一公1)、 村瀬研也1) 阪大院・医・保健、阪大・医・保健1) In the era of aging society, radiotherapy plays an important role in treatment of cancer. The quality assurance of radiotherapy is, however, unsatisfactory in Japan. In addition, the quality assurance of medical images for treatment planning of radiation therapy is important. It is difficult to collect images and patient information because of manpower shortage and expense. The purpose of this study is ・ To construct a system which collects medical images and patient information using Internet, and ・ To construct a server which works as quality assurance of the field, dose, and other important factors of radiotherapy all over the country. The characteristics of our system have the following features: ・ The system uses popular computers and general protocol. ・ The system is constructed at low price. ・ Only registered users can store, browse, and search for medical image files from remote institutions through Internet. ・ The users can communicate through the system using a communication pathway encrypted by SSH(Secure Shell). Recently, digital imaging systems have increasingly become common. In such a social trend, our system assuming digital imaging is expectable for the quality assurance of medical images in treatment planning of radiotherapy. |
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閉会の辞 17:42 〜17:52 |
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XX 一般口演 核医学I 9:10 〜 9:58 座長 福士 政広 |
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51. PET用DOI検出器開発：直列結晶配列 "Development of DOI detector for PET in series crystal arrangement" 梅原隆哉、村山秀雄1)、河合秀幸2)、稲玉直子、尾身健児、笠原竹博 千葉大・自然、放医研・医学物理1)、千葉大・理2) It is important to analyze the characteristic of a DOI detector for PET in order to research and develop it. The DOI detector that Murayama proposed before has many parameters. It is difficult to analyze the features and optimize the parameters. We experimented with the simpler 1-dimensional model. By that, we are able to analyze it easily. The result will also become basic data for a simulation of the DOI detector. There are some parameters of crystal. (Ex. the kind of crystal, a surface state, reflective material, etc) We arranged a block of 1x3 array crystals whose both sides are optically connected to two PMTs, and collected the output signals by using CAMAC ADC. The beam (width 1mm) extracted from the lead was applied to the center of a crystal. Point source is 137Cs. We experimented by changing various parameters. We are going to report the results. |
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52. PET用DOI検出器開発：異なる蛍光減衰時間の結晶配列 "Development of DOI detector for PET:Arrangement of different decay constant GSO crystals." 尾身健児、村山秀雄1)、河合秀幸2)、稲玉直子、梅原隆哉、笠原竹博 千葉大・自然、放医研・医学物理1)、千葉大・理2) We reported a depth of interaction (DOI) detector that has 3 stages in previous meeting. We developed this type of detector 4 or more stages by using 2 kinds of Gd2SiO5:Ce(GSO) crystals: the ratio of Ce is 1.5mol% and 0.5mol%. It is possible to identify the type of crystals using pulse shape discrimination, because GSO crystals doped different amount of Ce have different scintillation decay time constants. In this DOI detector, the crystal of interaction can be expressed on two 2-dimensional histograms by applying Anger-type position arithmetic after pulse shape discrimination. Miss positioning ratio of the detector using 2 kinds of crystals with pulse shape discrimination method is much less than the case using single kind of GSO, especially when the detector has 4 stages or more. We constructed the DOI detector with a 4-stage block composed of two kinds of GSO crystals. By irradiating γ-ray from 137Cs point source to it, two positioning contour image histograms corresponding to each pulse shape were obtained. On these histograms, the crystal of interaction can be easily identified. |
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53. PET用DOI検出器開発：U字型結晶配列 "Development of DOI detector for PET : U shape crystal arrangement" 笠原竹博、村山秀雄1)、河合秀幸2)、稲玉直子、尾身健児、梅原隆哉 千葉大・自然、放医研・医学物理1)千葉大・理2) In order to increase the efficiency of PET system, a detector having depth-of-interaction (DOI) information should be developed. We are studying about unit of the DOI detector that has blocks consists of 2x2 array and 3-stage rectangular scintillation crystals optically coupled at the bottom face to a position sensitive photomultiplier tube (PS-PMT). It is too complicated to grasp the light distribution in the block especially the crystal on the third stage has three directions of optical path. Therefore, we constructed block detectors having simpler structure. The detectors have only two directions of optical path in third stage. Its structure of the crystal is a 2x1 array and three stages in depth, 2x1x3 construction. The crystal of interaction is identified by the ratio of two output signals from coupled PS-PMT with crystals in the first stage of the block. We measured signals from PS-PMT by changing the conditions of 2x1x3 block detector. It is effective to evaluate misidentification of the crystal of interaction. |
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54. 計算機シミュレーションを用いた位置検出型PETディテクタの特性解析(II) "Characteristic Investigation of Depth of Interaction Detector for PET using Computer Simulation(II)" 山田 暁，羽石秀昭，村山秀雄1) 千葉大・工，放医研・医学物理1) In the last JSMP conference, we reported on a Monte Carlo simulator for a DOI (depth of interaction) PET detector unit composed of three-dimensionally arranged crystal blocks and photo-multiplier tubes. This time we improved this simulator by considering the dispersion of light output from each crystal element over the neighboring anodes of PS-PMT. The performance of the improved simulator was validated by comparing with the experimental results obtained by a prototype detector unit. Next, the effect of some parameters of detector such as refractive index of inter-crystal material, reflectance of optical reflector or the degree of dispersion of light output from each crystal element on the block discrimination were investigated and some useful results were obtained. |
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XXI 一般口演 核医学II 9:58 〜 10:34 座長 村山 秀雄 |
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55. モンテカルロ法を用いたベータ線の制動放射線スペクトルの算出 "Calculation of Beta-ray Bremsstrahlung Spectrum using Carlo Method" 馬場由香里、福士政広、齋藤秀敏、波戸芳仁1) 都立保健科学大、 高エネルギー研1) The therapy using Beta ray of Strontium-89 is operated to alleviate the pain of osseous metastasis. But, we cannot measure from outside whether short-range Beta-ray Strontium-89 accumulate at tumor area or not. Methods: The bremsstrahlung radiation spectrum was calculated by the EGS4 Monte-Carlo simulation method. The nuclide assumed Sr-89 and P-32. There was supposed to be the bone center of the soft tissue on the geometry. Radiation sources are two kinds of homogeneity distribution and surface distribution in the bone. Results: Sr-89 The radiation source did not affect the generation of bremsstrahlung radiation by the bone diameter. And, the thin bremsstrahlung radiation as soft tissue was abounding. It was not effective at bremsstrahlung dose in the source distribution. P-32 The bremsstrahlung radiation was more abounding than Sr-89. Conclusion: It was possible to show bremsstrahlung radiation data by the β nuclide. This EGS4 Monte Carlo simulation showed the useful data. |
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56. 教育用マルチタイプコリメータおよびマルチ分解能コリメータの開発 "Development of performance of the Educational Multi-type" 柳元裕子、福士政広、乳井嘉之、横井孝司1) 都立保健科学大、 島津製作所1) > We developed of performance of the educational multi-type collimator and multi-resolution collimator. Then, the basic performance of developed collimators is reported. Methods: It made image evaluation on the multi-type collimator using the thyroid gland phantom. The multi-resolution collimator evaluated uniformity and relative sensitivity. Result: The multi-type collimator indicated the characteristic image of each collimator. The multi-resolution collimator resolution was respectively HR at 8cm , AP at 12cm and HS at 15cm in diameter. The relative sensitivity was performance order of each collimator. Conclusion: The multi-type collimator and multi-resolution collimator are useful as an educational collimator. |
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57. 心筋SPECT画像における画質の劣化 "Degradation of reconstructed images in myocardial SPECT" 永瀬克、尾川浩一 法政大院・工 In myocardial single photon emission CT (SPECT), reconstructed images are distorted by motion of the heart during data acquisition, and attenuation and Compton scattering of gamma rays. Scattered photons originated in the liver also affect the quantitativity of reconstructed images. Moreover, Compton scattered gamma rays from the liver close to the heart cause degradation of the quality of SPECT images. This paper analyzed degradation of myocardial SPECT images for above points with the dynamic MCAT (DMCAT) phantom developed in University of North Carolina. Computer simulations were done considering the influences of motion of the heart, attenuation of gamma rays and the Compton scattered rays originated in the liver. Results suggested that a gated SPECT data acquisition, an exact attenuation compensation, and the data collection geometry which avoids the scattering rays from the liver were important to the quantitative myocardial SPECT image reconstruction. |
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XXII 一般口演 放射線防護I 10:46 〜 11:22 座長 岩波 茂 |
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58. 光刺激ルミネセンス線量計による診断用X線ビームモニタリング "Monitoring of diagnostic X-ray beams using optically stimulated luminescence" 原田康雄、境野利江、小林育夫1) 、佐藤健児2) 、岡野友宏 昭和大・歯・歯放、長瀬ランダウア1) 、日本歯科大・歯・歯放2) A nation-wide survey of entrance surface doses (ESD) for patients is important as a key strategy for optimization of radiation protection in medical X-ray examinations. To measure the ESD, we studied remote monitoring of diagnostic X-ray beams using an optically stimulated luminescence (OSL) dosimeter of Al2O3:C. The OSL dosimeter, Luxel badge (Nagase Landauer Ltd.), was irradiated by X-ray beams of effective energy from 27 to 52 keV at tube potentials from 50 to 120 kV which are commonly used in X-ray examinations excluding CT and mammography. Responces of the OSL dosimeter were compared with the exposures and the effective energy calibrated by an ionization chamber; results indicated that they were consistent with the values of the ionization chamber within 3-5% at 50 kV, but their differences increased with increasing tube potentials reaching 15% at 120 kV. This was caused by the differences of the quality and/or the homogeneity of beams between calibration of the OSL dosimeter and measurement of X-rays. The ESD monitoring of diagnostic X-ray beams proved to be accurate within 5-10% at 50-70 kV and 10-15% at 90-120 kV using the OSL dosimeter. |
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59. Body Mass IndexによるフォトタイマＸ線撮影の被曝線量予測
−胸部正面撮影および腹部正面撮影について− "Prediction of entrance surface absorbed dose in dignostic radiography by body mass index. - Frontal radiography for the chest and abdomen -" 松本光弘、太田誠一、井ノ上信一、内藤博昭1) 阪大附病・放、阪大・医・保健1) In the radiographic section of Osaka university hospital, as an additional function of HIS-RIS system, real-time "patient entrance surface absorbed dose calculation system" (PEDOCALs) has been developed and working from January, 2000. This PEDOCALs is a system which cooperates with an ordering system, and an entrance surface absorbed dose can be calculated and displayed immediately after taking radiographs. Correlation between body mass index (BMI) indicating patient's body features and an entrance surface absorbed dose obtained from this system was analyzed in routine frontal radiography using photo-timer for the chest (n=15455) and abdomen (n=3619). As the result, there found positive correlation between BMI and entrance exposure dose with the following correlation ; R2=0.997 (p<0.001) for the chest radiography , and R2=0.951(p<0.05) for the abdomen. Mean values of the skin surface absorbed dose in patients with standard body features (an average of BMI;22.0 kg/m2) were 0.23 mGy in the chest radiography and 2.05 mGy in the abdominal radiography ,respectively. It was proved that patient's adsorbed dose in photo-timer radiography is predictable based on his/her body features. |
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60. 診断領域Ｘ線の鉛スラブ遮蔽における光子ビルドアップの特徴 "Properties of photon buildup in lead shielding slab against diagnostic x rays." 加藤二久、加藤 洋、根岸 徹、大谷浩樹、乳井嘉之、福士政広、齋藤秀敏、 入船寅二 都保健大・放 Properties of photon buildup in lead shielding slab were investigated in diagnostic x ray energy region. The attenuated photons were divided into four groups, primary photons, once interacted photons, multiple interacted photons to forward direction and back scattered photons. The attenuation factors of the first two groups were analytically calculated. The scatter-to-primary ratios (SPR) of the later two components were estimated by means of Monte Carlo simulation as a function of incident photon energy and attenuation layer ｔｈｉｃｋｎｅｓｓ. The scattered photons in the third component represented to be functionｓ similar to the radioactive equilibrium, in which the decay constant and the time were replaced by the attenuation coefficient and the attenuation thickness. The buildup of the characteristic x rays represented similar formula in which the decay constant of the daughter was less than that of the mother. The last component represented to be a very small contribution in ｔｏｔａｌ SPR and reached to saturation for a thick backscattering layer. The SPRs of these components were parameterized into analytical functions, which kept good accuracy up to the attenuation thickness more than twenty times of the mean free path of the incident photons. |
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XXIII 一般口演 放射線防護II 11:22 〜 11:58 座長 佐藤 健児 |
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61. ＣＴでの線量最適化アプリケーション「Care Dose」の開発と評価 "The Development and evaluation for application of adequate X-ray exposure: 'Care Dose'" 佐藤夏子、小松加奈子、小酒部和洋 シーメンス旭メディテック Recently, multi-slice CT has been developed and scan coverage has extended drastically. Therefore, total radiation exposure might increase. We developed dose modulation application according to X-ray attenuation. Basic concept of our algorithm is to estimate attenuation applying previous half scan. Substituting this application to the shoulder phantom, we can reduce the X-ray dose 70 % at most. At the same time, the shower artifact caused by uneven X-ray attenuation one during gantry rotation can be decreased because the error over reconstruction is minimized. |
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62. X線防護衣素材の研究 "Study of X-ray Protective Clothes material" 泉川亜衣, 福士政広, 波戸芳仁1) 高エネ研1) The X-ray protective clothing is used for X-ray protection of the medical field. The material of the X-ray protective clothing is generally a lead. Therefore, in order to raise the protection effect in which the weight increases. Then, we studied the material of the light X-ray protective clothing. Methods: The shielding experiment of the material of the weight of 0.25 mm and 0.35mm lead equivalent becoming was done. The incidence X-ray are X-ray tube voltage 60kV, 70kV, 80kv, 90kV and 100kV. And, the shielding material used materials atomic number of from 31 to 92. Results: The optimum protection material is different by X-ray tube voltage. The optimum protection material was X-ray tube voltage 60 kV at Ag, from 70 to 80kV at Sb and from 90 to 100kV at Pr. Conclusion: We studied the material of the light X-ray protective clothing . As the result, Ag, Sb, Pr was promising as a protection material. |
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63. 屋内空気中ラドンの1/fゆらぎと1/f2ゆらぎ "1/f and 1/f2 Fluctuations in Indoor Atmospheric Radon" 小林恒夫 福島医大・物理 Since 1987, I have made researches for radon in air. Behavior of atmospheric radon (222Rn) is an issue of wide importance to radiation protection, earthquake prediction, etc. Method of my researches have changed from intermittent one to continuous one recently. The present report deals with 1/f and 1/f2 fluctuations observed in data from 1998 to 1999. Pylon TEL (Lucas chamber with active air collection of 0.5L/min) monitored the concentration of indoor atmospheric radon every one hour. Hourly data of radon were recorded except some missing values due to the need of replacing desiccant. Power spectra were obtained with Fourier integration of auto-correlation function (Wiener-Khintchine theory) using SPSS 10.0J. Daily integrated data indicated 1/f0.3 to 1/f fluctuations, whereas hourly data indicated essentially 1/f2 fluctuation. Besides the well-known one-year and one-day period, radon indicated several periodicities: 3 to 5 day periods that concern passage of air masses, and 20 to 30 day periods that are attributed to meteorological phenomena corresponding to the rotation period of the sun. |
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XXIV 一般口演 ＱＣ/ＱＡI 13:30 〜 14:18 座長 山口 道弘 |
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64. 医用電子機器のEMCに関する検討 "EMC of the medical electronic instrument" 渡辺陽1)、杉本正樹1)、大嶋友範、松原孝祐、山下勝、中山和也、小島一彦 金沢大院・医1)、金沢大・医・保健 Recently the various electronic instruments that caused the high-power electromagnetic field and/or affected by the field are in use in the medical facilities. Especially It regarded as an important problem that the function error of the medical electronic instruments are caused by the electromagnetic waves radiated from the portable phone, so that the portable phone is prohibited a use in the medical facilities. The type and output of portable phone differ so that the level of error is various, but in any case the electromagnetic field that effect on many medical electronic instruments cause regardless of the call, so that user have to restrict to use place and use time. In this work, we considered the effect of many medical electronic instruments in the respect of EMC (Electromagnetic compatibility) in the medical facilities. And so we report results that simulated the intensity distribution of electromagnetic field around the portable phone and measured it around the telemeter-type electrocardiogram (ECG) and computer display. |
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65. 医療施設における電磁環境 "Electromagnetic Environment in Medical Facility" 杉本正樹1)、渡辺陽1)、内田智子、長部恭輔、片町健、中山和也、小島一彦 金沢大院・医1)、金沢大・医・保健 Recently there has been a dramatic increase in the number of radio frequency emission sources that have entered medical treatment areas. For example Personal computers, digital pagers, hand-held radios, cellular phones, and wireless input devices have all become more prevalent in the contemporary clinical environment. In addition there is the latest large-sized medical equipment which is MRI and CT and LINAC etc. in medical facilities. These can suffer interference from an electromagnetic field. electromagnetic interference (EMI) causes medical equipment to malfunction. Presently electromagnetic compatibility (EMC) in medical electronic instrument usually has determined only IEC60601-1-2 which consist of EMI and immunity. We measured medical equipment in medical facilities (MRI, CT, LINAC, nurse center , sickroom, ICU etc.) to know electromagnetic environment and to establish evaluation and guideline for electromagnetic field . |
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66. Computed Radiography スキャナーシステムのPerformance Assessment "Computed Radiography Scanner Systems' Performance Assessment in Dental Office Usage" 早川吉彦、森 俊道、山本一普、和光 衛、Allan G. Farman1) 東京歯科大・歯放、ルイビル大1) Background: Certain computed radiography (CR) scanner systems using photostimulable phosphor (PSP) plates are now available for use in the dental office. Hence, it is appropriate to conduct comparative performances tests of these systems. Objective: To assess computed radiography scanner performance in relation to the image processing methods applied for digital readout of radiographs used in dental practice. Methods and Materials: Performances of the Combi-X (Orex CR Technologies, Israel), DenOptix (Dentsply/Gendex, USA) and Digora (Soredex/Orion, Helsinki, Finland) were compared. Differences in the sensitivity, the signal-to-noise ratio, fading, and resistance to the ambient light were examined both for white and for blue PSP plates (Fuji Film Medical, Japan and Agfa-Gevaert, Belgium). Photo-multiplier amplification gain was examined in relation to image noise for the Combi-X system. The unsharp-masking filter performance of the Combi-X was also examined. Results: White PSP plates were characterized by the high sensitivity and low resistance to light exposure compared with blue PSP plates. The Combi-X PM gain could be set for each radiographic examination in the dental office. Since this is not a control tool provided with the DenOptix system, adjustment of 16 bit-depth data viewed on 8-bit display was found to be important. Since the default setting of the unsharp-masking-filter for the Combi-X is moderate, anatomical structures were clearly demonstrable despite increased image noise Conclusions: It is concluded that blue PSP plates have advantages over white PSP plates in terms of dose needs and resistance to light exposure. Images made using the Combi-X were noisier than those made with the DenOptix and Digora systems; however, this did not prevent adequate detail discrimination. |
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67. 胸部ＣＴ検診のための精度管理-ＣＴ撮影の精度管理マニュアル作成について "Standard for the Performance of Lung Cancer Screening CT ―Preparation of the Quality Control Manual of CT Imaging" 松本 徹、伊藤茂樹1)、岡本英明2)、高山俊之3)、津田雪裕4)、中村義正5)、 西澤かな枝、花井耕造6)、松本政雄7)、村松禎久8) 放医研・重粒子セ、名大・保健1)、大阪成人病セ・放診2)、 京都科学3)、神奈川県予防医学協会・放技4)、東京都予防医学協会・診放5)、 国立療養所神奈川病院6)、阪大・保健7)、国立がんセ中央病院・放診8) In incorporating CT imaging into lung cancer screening, an essential issue is to establish a QA/QC system of CT imaging by standardizing image quality and exposure dose. In this paper, we reported on the following matters related to the preparation of the quality control manual of CT imaging for lung cancer screening from a standpoint of the Society of Thoracic CT Screening (TCS):1) what is each component of the QC manual, 2) how each QC component can be organized ,3) how to actually operate them, 4) discussion of problems related to the composition and operation of a QC system. |
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XXV 一般口演 ＱＣ/ＱＡII 15:40 〜 16:16 座長 今村 恵子 |
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68. 外部照射（Ｘ線）の線量に関した調査について "An Investigation of Absorbed Dose Irradiated by External X-ray Beam " 田伏勝義、遠藤真広1)、速水昭宗2)、中村 譲3)、内山幸男4)、川越康充2)、 榎戸義浩3)、西台武弘5)、石倉 聡6)、小高喜久雄6)、新保宗史6)、 西尾禎治6)、池田 恢6) 名大・医・保健、放医研・医学物理1)、阪大2)、埼玉がんセ・放治3)、 愛知がんセ・放治4)、京都医技短5)、国立がんセ・放治6) Recently, medical accidents in radiotherapy have reported over doses due to mistake of data input for monitor dose calculation system in Japan and troubles of programs for treatment planning system in a foreign country. Therefore, we decided to investigate the state of art for the quality assurance (QA) and quality control (QC) of external X-ray therapy equipments and treatment planning systems in Japan and made investigation sheets consisted of two parts roughly. One is the general questionnaire of radiotherapy department composed of four items. The other is composed of 20 items and related to QA/QC of the chamber, the calculation dose, the monitor unit, wedge and other filters, and treatment planning system. Investigation sheets will be send about two hundred institutes in Japan including visits of measurement and interview. The results of investigation will be presented at the Meeting of the Society. |
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69. 埼玉県立がんセンターにおける外部照射治療患者のモニタ線量計算の実態と問題点 "Actual Conditions of Human Error in Calculation for Monitor Dose of External Beam Therapy in Saitama Cancer Center" 中村 譲、水野秀之、榎戸義浩、黒川 晴、阿部 靖、林 行俊、松本 慎、 渡辺義也、福田 公 埼玉がんセ・放治 3 treatment equipments of 2 linear accelerators and a microtron are installed in Saitama Cancer Center. Numbers of new patients and total treatment patients treated by external beams of high energy X-rays and electrons in fisical 2000 are 1136 and 23961 persons, respectively. More than about 100 patients were treated per day in our radiotherapy department. We decided to recalculate and check patient monitor dose values calculated for the prevention of the wrong irradiation from February 2000. By the survey from June 2000 to April 2001, total numbers of patients, treatment sites and irradiation ports calculated for both high energy beams of X-rays and electrons were 1587, 1996 and 3485, respectively. Human errors of more than 1% of difference in patient monitor dose calculation were occured in 25 cases and its incidence is 1.5% per patient treated. Human errors in detail were as follows: 1, 6, 12, 16, 18 and 25 cases for ＞30 %, 15-10%, 9.9-5%, 4.9-3%, 2.9-2% and 1.9-1% of difference, respectively. Recalculation and check in patient monitor dose calculation are essential for QA/QC program of dose in radiotherapy procedure. |
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70. Global Medical Device Nomenclatureについて "An Introduction to Global Medical Device Nomenclature" 加藤二久、飯沼 武 都保健大 放、放医研 In Jun. 2001, Global Medical Device Nomenclature（GMDN）was published by Technical Committee for Quality Management and Corresponding General Aspects for Medical Devices（TC210）of International Standard Organization（ISO）. Purpose of the GMDN is to globally identify the type of medical device which may give rise to a medical accident and to construct a database which can be accessed by medical staff and legal regulation agencies all over the world. The present version contained the definitions of 3557 basic terms (Preferred Terms) and more than 3000 synonyms. The Working Group (KKS) of TC210 Committee in Japan Federation of Medical Devices Associations is now planning to translate it into Japanese and to be used in reviews of medical devices by MHLW for compliance with Japanese Pharmaceutical Affairs Law. It is expected that terminology will be unified in all the medical fields with the use of GMDN in Japan. Japan Association of Medical Physics should take an initiative to participate in this GMDN and inform to medical soceities this important system of nomenclature. |
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XXVI 一般口演 磁気共鳴I 16:30 〜 17:06 座長 加藤 博和 |
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71. 超偏極Xeガスを用いた高感度磁気共鳴における緩和時間T1へのガラス材質の効果 "Effect of glass materials on the relaxation time T1 in the hyperpolarized Xe-129 magnetic resonance" 神谷貴史、清水隆興、柳川康洋、木村敦臣、藤原英明 阪大・医・保健 Nuclear magnetic resonance using hyperpolarized noble gases has come to attract attention in the fields of physics, chemistry and medicine. Here, we have built a simple supplying system of hyperpolarized Xe gas and effect of glass materials on the relaxation time T1 of Xe-129 gas entrapped in glass tubes from different sources is measured. This type of basic data will be useful for future development of new apparatus for the hyperpolarized noble gas supplying system. Our results showed that pyrex gives lower relaxation time than others, i.e. longer than the silica glass to which the lowest T1 value is expected because of the lack of metallic component such as ferric oxide. The plastic cylinder was also measured for a reference. The teflon cylinder gave shortest relaxation time and concluded to enhance relaxation most significantly among the materials studied. |
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72. Improvement of slice characteristics in conventional RF pulse 山口弘次郎、梅沢栄三、久場匡、安田成臣、小原 健 藤田保健大・衛生 Introduction Generally, the sinc function is used for the RF pulse in MRI. Recently, for the purpose of shortening TE, symmetric RF pulses with decreased π numbers and asymmetric RF pulses, which have asymmetric π numbers at + and -, are used. However, the slice profile is deteriorated by decreasing the π number . The degradation of the slice profile also affects the slice charactristics . We report some results of the RF pulse simulations to improve the slice characteristics. Method We compare the consequences of our modified RF pulse with ones of the standard RF pulse of the sinc function. The functions we have used are Gaussian, Sinc*Gaussian and Hypersinc. The symmetry of the RF pulses are made to be symmetric and asymmetric. The evaluation items are Slice Profile, Cross Section, Slice Charactristics and Phase Diagram. In our simulations we solve the Bloch equation numerically using the Runge Kutta method with Mathematica. Result Fig.1 shows the results of our simulations in which the sinc function and sinc*gaussian function are used for the RF pulse (the π numbers:±4π, SEP time:4.0 msec, slice thickness:10 mm). In our simulation, the RF pulse of a sinc+gaussian function gives best characteristics. From this, it is shown that the RF pulse characteristics can be drastically improved by using the general function. The image confirmation will be carried out in future, and the usefulness of the same RF pulse will be examined. |
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73. ファンクショナルMRIと近赤外分光測定との結合理論 "Theory to Bridge Functional Magnetic Resonance Imaging and Near Infra-red Spectroscopy" 山本 徹、加藤俊徳1) 2) 北大医短、ミネソタ大・医・磁気共鳴セ1)、 濱野生命科学研究財団・小川脳機能研2) A signal increase in functional Magnetic Resonance Imaging (fMRI) is believed as a result of a decrease of deoxygenated hemoglobin (deoxyHb) contents in neural-activation area, because deoxyHb is a paramagnetic substance causing a signal decrease in MRI. However, discrepancies from this canonical blood oxygenation level dependent (BOLD) theory have been pointed out by studies using optical techniques which measure hemoglobin changes. To explain the paradoxical correlation between MR signal and deoxyHb changes, we developed a new theory to bridge MR signal and hemoglobin changes. We focused on the capillary influence which has been neglected in hitherto considerations of fMRI. A volunteer performed the same multiple-word repetition task separately with fMRI and near infrared spectroscopy (NIRS). Paradoxically to the canonical BOLD theory, both fMRI signal and deoxyHb contents increased in Broca tissue where capillaries are dominant. On the other hand, fMRI activation in auditory area near large veins followed the canonical BOLD theory. Our theory explained both paradoxical and canonical phenomena quantitatively, and derived hemodynamics of oxygen extraction and hemoglobin-content changes in activation. We conclude that the discrepancy from the canonical BOLD theory is caused by less importance of the capillary influence. Combination of fMRI and NIRS reveals hemodynamics in activation by our new theory. |
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XXVII 一般口演 磁気共鳴II 17:06 〜 17:42 座長 藤原 英明 |
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74. ダイナミックMRIを用いた脳血流量の定量に関する検討 "Quantification of Cerebral Blood Flow using Dynamic Susceptibility Contrast-Enhanced Magnetic Resonance Imaging" 篠原雅昭、村瀬研也1) 、山嵜洋一、北田孝幸、西村圭弘、飯沼正博、 榎卓也1) 、菊池恵一1) 、三木均2)、池添潤平2) 阪大院・医・保健、阪大・医・保健1) 、愛媛大・医・放射2) Deconvolution analysis based on singular value decomposition (SVD) has been widely accepted for quantification of cerebral blood flow (CBF) from dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI). When using this method, the elements in the diagonal matrix obtained by SVD are set to zero to eliminate singular values when they are smaller than the threshold value given beforehand. However, the effect of this threshold value on the accuracy of the calculated CBF values has not been investigated in detail. Then, the purpose of this study was to investigate the effect of the threshold value used in SVD on the accuracy of CBF quantification using computer simulations. The estimated CBF values largely depend on the threshold value. They decreased with an increase of the threshold value. The threshold value at which the estimated CBF value is equal to the true value changed depending on the model of vascular transport. In conclusion, our results suggest that the threshold value should be carefully considered when quantifying CBF in terms of absolute values from DSC-MRI using deconvolution analysis based on SVD. We believed that this study will be helpful for selecting the threshold value in SVD. |
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75. シネ位相コントラストMRIを用いた定量的血流解析による大動脈解離の "Quantitative Blood Flow Analysis to Evaluate Expanding Tendency of the False Channel in Aortic Dissection Using Cine Phase-Contrast MR" 解離腔拡大傾向の評価 井内洋介、内藤博昭、小縣裕二、山本修司 阪大院・医・保健 This study is to quantitate aortic blood flow and examine its correlation with morphology in aortic dissection. Subjects are 14 patients with chronic aortic dissection (DeBakey-3 and postoperative state of DeBakey-1). Cine phase-contrast(PC) MR imaging was performed at the mid-thoracic axial section using 1.5 T system. Blood flow volume was measured for non-dissecting or repaired ascending aorta, and true and false channels of thoracic descending aorta with applying 3 baseline compensation methods for the false channels; 1) end-diastolic velocity in false channel is zero, 2) end-diastolic velocity in true channel is zero, 3) velocity of stationary background is zero. Then volume and pattern of blood flow in the false channels was analyzed in correlation with expanding tendency of the aorta. As the results, flow volumes with method 3) showed reasonable value; ascending 4.15±1.35 L/min, true 2.01±1.00 L/min, false 1.15±0.52 L/min, and reasonable proportion of descending (true + false) to ascending flow; 73±14 %. False-to-true flow ratio was well correlated linearly with section area ratio of the both channels (r=0.76, p<0.001). Follow-up CT/MR imaging for the patients revealed that the false channels having large flow volume or remarkable vortex flow showed higher expanding tendency. Cine PC imaging was proved to be utilizable for prognostic evaluation of patients with chronic aortic dissection. |
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76. 高速三次元拡散強調ＭＲＩの開発と生体計測への応用 "Development of a Fast Three Dimensional Diffusion Weighted MRI" 沼野智一、西村克之、本間一弘1) 茨城医療大、産業技術総合研究所1) The diffusion phenomena of water molecule can be detected with diffusion weighted imaging method has been proved to be useful for medical diagnosis of cerebral disease and physiological studies of neural activity. Every molecule in biological tissues may diffuse and move randomly in three dimensions. Therefore, a new MRI technique for three-dimensional diffusion imaging is strongly required for clinical diagnosis. In this study a pulse sequence for a three-dimensional MRI for molecular diffusion enhancement is proposed. In this method, the nuclear magnetic moment is kept under SSFP (Steady State Free Precession). In the proposed method FA (Flip Angle) can be made large, and the signal strength depending on the length of FA. As a result, S/N ratio increased. The acquisition time is almost 5.21 minutes for the image of 256x256x64 voxles with effective TR of 2500msec and effective TE of 120msec, respectively. Images are enhanced depending on the relaxation time and diffusion coefficient of biological tissues, and the intensity of acquired signal reflects the molecular concentration. MRI echos in some tissues with large relaxation time such as CSF is strongly enhanced. Feasibility study was performed using the phantom and human head images. |
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受付開始 ９：００〜 |
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青少年のための講演会「医療における放射線―放射線は人類の敵か味方か 座長 内藤博昭、稲邑清也 |
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77. 最近の癌の治療の先端技術 -その1- 重粒子線治療 遠藤真広(放医研) 10:00-10:30 |
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78. 最近の癌の治療の先端技術 -その2- IMRT，3次元的治療，トモセラピー 伊藤 彬 (癌研) 10:35-11:05 |
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79. あなたの治療の最適治療はどのようにみつけるか ―コンピュータとデータベースの役割― 稲邑清也(大阪大学医学部医用工学講座) 11:10-11:40 |
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質疑応答 11:40-12:00 |
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80. 癌の診断の最新情報：マルチスライスCT，MRI，超音波，核医学，コンビームCT 山口道弘(羽曳野病院) 13:00-13:30 |
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81. 射線被曝についての正しい知識と的確な処置方法 森川 薫(広島国際大学) 13:35-14:05 |
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82. 放射線分野で働く科学者と技術者の活躍 丸橋 晃(筑波大) 14:10-14:40 |
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83. 宇宙旅行と放射線 池永満生(前 京都大学放射線生物研究センターセンター長) 14:50-15:20 |
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質問と討論 15:30-16:00 |
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※ 発 表 1. 一般口演の時間は１題につき口演9分、討論3分を基準とします。 2. 各会 場にスライドプロジェクター35 mm１台、ＰＣプロジェクター１台を用意します。OHP の用意はありません。スライドの枚数は任意とします。 ＊スライドは容易に判別でき るもののみを御使用下さい。 3. 演者は発表１時間前までにスライド受付にお越し下さ い。 ※ スライドはプラスチックマウントのみをご使用下さい。 ※ ＰＣプロジェクタ ーのご利用は原則として、スライド受付でフラッシュメモリへ発表ファイルをコピー します。コピー用のフラッシュメモリ、同各種アダプター（ＴＹＰＥII）はスライド 受付で用意します。お手持ちのノートＰＣカードスロット（ＴＹＰＥII）が装備され ていない場合にはフラッシュメモリやＭＯディスク等では発表ファイルをご持参下さ い。なお本年７月発売のOffice XP versionのPower pointを特に御使用予定の方は９ 月14日迄に下記に御連絡下さい。 ※ 第82回 日本医学物理学会学術大会に関する問い 合わせ先 〒565-0871 大阪府吹田市山田丘 1-7 大阪大学医学部保健学科医用工学 講座 稲邑研究室内 JSMP2001事務局 TEL&FAX 06-6879-2570 E-ma il: jsmp2001@sahs.med.osaka-u.ac.jp |