@article{oai:iuhw.repo.nii.ac.jp:00000190,
 journal = {国際医療福祉大学紀要, Bulletin of International University of Health and Welfare},
 month = {Aug},
 note = {SPECTの画質を改善するため、視野中央部の感度を高くした中央部重点方式のSPECT装置を提案し、20cm直径の円柱線源に対する3検出器型SPECTの画質をシュミレーションにより評価した。3検出器型SPECTとして、3検出器とも平行多孔コリメータを装着した通常のシステム、3検出器とも同じ焦点距離のファンビームコリメータを装着したシステム、および互いに異なる焦点処理のファンビームコメリータを装着した中央部重点方式のシステムを考察した。その結果、各システムの視野中央で統計雑音は相対値でそれぞれ100、80、57となり、また、視野の広い範囲にわたり画質の均一化が図られ、画質改善に対する中央部重点方式の有効性が示された。, Single photon emission computed tomography (SPECT) systems are widely used as useful diagnositic instruments in nuclear medicine. Most of them are composed of a single or a couple of rotating gamma cameras each equiped with a parallel hole collimator. Diagnosistic images obtained with such system are in general of poor statistics due to the limitation of the number of detected photons, especially in the vicinity of the object center because of strong attenuation of photons, in the body. Quality of such images can be improved by modifying collimator systems. A fan-beam collimator provides an increased sensitivity to a certain extent with reduction of field-of-view, compared with a parallel hole collimator. Therefore, one of approaches for the improvement is the use of a combination of more than two fan-beam collimators whose focal lengths are different from one another. A proper selection for focal lengths produces higher sensitivities at the central region than the peripheral in the field-of-view. Evaluation of statistical noises in reconstructed images was made by computer simulations for three types of triple gamma camera SPECT systems, and the noise in terms of standard deviation at the center of the image obtained with the proposed system was successfully reduced to 57% of that with the conventional system.},
 pages = {23--28},
 title = {中央部重点方式による3検出器SPECTの画質改善},
 volume = {1},
 year = {1996}
}