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Title: 超高エネルギー用高空間分解能・高感度コリメータの設計について
Other Titles: Design of ultra-high-energy, high-resolution and high-sensitivity collimators for gamma cameras.
Authors: 久保, 直樹1 Browse this author →KAKEN DB
Authors(alt): Kubo, Naoki1
Keywords: ultra-high-energy imaging
converging collimator
pinhole collimator
Issue Date: Jul-2004
Publisher: 日本放射線技術学会 北海道部会
Journal Title: 北海道放射線技術雑誌
Volume: 64
Start Page: 45
End Page: 51
Abstract: 小型被写体用超高エネルギー用コリメータの設計と作製を行った.作製したピンホールコリメータは,径0.6 mmで許容角度は13°であった.このピンホールから被写体までの距離と幾何学的感度,および距離と視野サイズの関係を計算した.次にガンマカメラに装着して18Fにおける総合空間分解能と総合感度を測定した.また超高エネルギー用コンバージングコリメータも設計した.ピンホールコリメータの計算結果は,距離を近づけると幾何学的感度は高くなったが,視野は狭まった. 測定した結果においてFWHMは2.4 mm,FWTMは9.5 mm,総合感度は6.8 counts sec –1 MBq–1であった.一方,コンバージングコリメータは視野の大きさの制限,視野周辺部の感度低下を受けないことが示唆された.このようにピンホールコリメータで超高エネルギーの高空間分解能撮像に成功した.またコンバージングコリメータの方は,臨床機への応用も可能と考えられた.
Recently, small object imaging using positron emitters, such as fluorine-18-2-deoxyglucose, has focused on basic nuclear medicine techniques. We have designed and developed ultra-high-energy high-resolution collimators for small object imaging. Firstly, we produced an ultra-high-energy pinhole collimator. The thickness of the lead shielding was 30 mm. The pinhole diameter of knife-edge aperture was 0.6 mm. The acceptance angle was 13°. This cylinder was equipped with a non-collimator gamma camera at a distance of 30.5 cm. The radius of rotation was 6 cm and the magnification was 5.1 times. In simulation calculations, as the pinhole-object distance decreased, geometric sensitivity increased geometrically. However, as the pinhole-object-distance decreased, field-of-view (FOV) decreased linearly. Spatial resolution was measured using a line source of 18F and was 2.4 mm at full-width-at-half-maximum and 9.5 mm at full-width-at-tenth-maximum. The sensitivity of the system was 6.8 counts sec–1 MBq–1 using a point source of 18F. In addition, sensitivity at the rim of FOV was lower than that at the center. Next, we designed an ultra-high-energy converging collimator. It was found that the converging collimator had uniform sensitivity over the FOV. Also, the FOV at smaller collimator-object distances was not as restricted as the ultra-high-energy pinhole collimator. Thus, we demonstrated that high-resolution images for ultra-high-energy imaging could be acquired using the pinhole collimator. Moreover, we believe that the ultra-high-energy converging collimator could be available for a clinical study.
Type: article (author version)
Appears in Collections:医学院・医学研究院 (Graduate School of Medicine / Faculty of Medicine) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 久保 直樹

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