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瀬川 麻里子; 甲斐 哲也; 大井 元貴; 高峰 潤; 呉田 昌俊
Proceedings of 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference (2011 NSS/MIC) (DVD-ROM), p.385 - 392, 2011/00
In the present study, we aimed to develop a neutron imaging system which allows us to visualize transient phenomena with high spatial resolution and real-time. Therefore, a camera (CMOS, 48 frame/sec) system which could obtain one TOF image resolved into narrow energy ranges with an each single pulsed neutron consecutively in the energy region from 0.01 to a few keV was constructed. Qualities of the images obtained with the system, such as spatial resolution, neutron energy selectivity of the system, and capability for visualization of transient phenomena, were examined experimentally. The results figured out that the spatial resolution defined by modulation transfer function was 1.8 at En 
0.01 eV. And the energy selectivity was confirmed by the scanning of the sample made by Au, which had a large resonance at En = 4.9 eV. Finally, the system could visualize the transient phenomena to fall the Fe powder on a sandglass. The experiments showed that the system can visualize the real-time neutron energy resolved images with a good spatial resolution even at transient phenomena.
藤 健太郎; 中村 龍也; 坂佐井 馨; 曽山 和彦
Proceedings of 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference (2011 NSS/MIC) (DVD-ROM), p.347 - 349, 2011/00
低線量率
線照射下での利用研究のため、ポリメタクリル酸メチル・プラスチック光ファイバ(PMMA POF)に対する線照射試験を行った。紫外線及び近赤外線領域に照射による透過光量の損傷ピーク、及び全波長領域に透過光量の改善を確認することができた。また、吸収線量の増加とともに照射損傷は増大し、ある線量に達すると飽和することを確認した。ここで、飽和する吸収線量は線の吸収線量率によって変化することがわかった。よってPMMA POFを低線線量率下で使用する際には、その線量率を考慮に入れる必要がある。透過光量の改善も同様に吸収線量率によって変化し、善良率が低いほど改善量が大きいことが確認できた。
中村 龍也; 安田 良; 片桐 政樹*; 藤 健太郎; 坂佐井 馨; 美留町 厚; 海老根 守澄; 曽山 和彦
Proceedings of 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2011), Vol.1, p.382 - 384, 2011/00
シンチレータと波長シフトファイバ読み出しによる高位置分解能型中性子イメージ検出器を開発している。本検出器ではテーパー付きファイバ光学素子(FOT)をシンチレータと波長シフトファイバの間に組み込むことで中性子による発光を光学的に拡大し高位置分解能を実現しようとするものである。今回、検出視野の拡大を目指し従来の小視野FOT(2.6
2.6mm、角型)から直径20mm(円形)の大面積品に改良を行いその特性試験を実施した。その結果、大型FOTでは従来品よりも光透過率が20
低減するものの位置分解能は従来と同様の0.26
0.07mmを保持することがわかり、有効面積314mm
、有効ピクセルサイズ0.170.17mmである高分解能型検出器となることが確認できた。
河地 有木; 山口 充孝; 長尾 悠人; 鈴井 伸郎; 藤巻 秀; 神谷 富裕; 小高 裕和*; 国分 紀秀*; 武田 伸一郎*; 石川 真之介*; et al.
no journal, ,
In order to extend the application of Compton imaging to the fields of medicine and biology, the imaging quality and quantitatively of Compton camera systems must be improved by correcting and normalizing spatial distortions. Several techniques have been developed for correcting the imaging errors in radionuclide-based imaging systems used to quantitatively analyze target physiological functions. Spatial distortion can be corrected by integrating individually reconstructed peaks of imaging data obtained by a Compton camera with the peaks of point sources. To improve the efficiency distortion, the individual detector efficiencies are normalized by flat panel phantoms, which is equivalent to the image of efficiency map of the camera geometry. Currently, we are constructing a Si/CdTe Compton imaging system. The imaging system has high spatial and energy resolutions and a wide energy range. We performed imaging experiments by placing point sources of 
Ba (364 keV) and 
Na (511 keV) in a reticular pattern at intervals of 20 mm within an FOV in front of the camera. As a result, an intensity distribution map of each source and distorted images point source showing the forms of elliptical object around the corner of the FOV were obtained. Such a distortion is a marked characteristic of Compton imaging at near-field area of camera head for medicine and biology.
