| Japanese |
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| Title | 回転スリットを用いたコーデット・アパーチャ・イメージング |
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| Subtitle | 原著 |
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| Authors | 田中栄一*, 飯沼武**, 松本徹**, 有水昇*** |
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| Organization | *放射線医学総合研究所 物理研究部, **臨床研究部, ***千葉大学医学部放射線科 |
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| Journal | 核医学 |
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| Volume | 13 |
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| Number | 2 |
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| Page | 103-110 |
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| Year/Month | 1976/4 |
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| Article | 原著 |
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| Publisher | 日本核医学会 |
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| Abstract | 「1. 緒言」最近, コーデット・アパーチャ・イメージングと称する方法によって, RIシンチグラフィにおける画質, 信号対雑音比(S/N比)等を向上しようとする試みに大きな関心がもたれ, 活発な研究が行なわれている. 一般化されたコーデット・アパーチャ・イメージングにおけるデコーディング法, S/N比および雑音の性質等については別に報告した. その結果によると, 十分高感度の検出器(たとえばアンガー型シンチカメラ)を用いて計数の統計変動がイメージの主要な雑音となる場合, 少なくとも十分大きい一様線源にたいしてはいかなるコーデット・アパーチャを用いても同じ解像力を得るように最適設計されたピンホールに比してS/N比を改善することはできない. しかし, 1つのシンチグラムについて画像処理系を変化することによって種々の解像力で観察する場合を考慮すると, 解像力のある範囲にわたってS/N比を高く保つことが望ましいと考えられる. 適当なコーデット・アパーチャを用いると, このような特性をもったシンチグラムが得られる可能性があることはすでに上記報告に指摘した. |
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| Practice | 臨床医学：一般 |
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| English |
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| Title | Coded Aperture Imaging Using a Rotating Slit |
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| Subtitle | Original Articles |
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| Authors | Eiichi TANAKA, Takeshi IINUMA, Toru MATSUMOTO, Noboru ARIMIZU* |
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| Organization | National Institute of Radiological Sciences, *Department of Radiology, Chiba University School of Medicine |
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| Journal | The Japanese Journal of nuclear medicine |
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| Volume | 13 |
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| Number | 2 |
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| Page | 103-110 |
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| Year/Month | 1976/4 |
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| Article | Original article |
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| Publisher | THE JAPANESE SOCIETY OF NUCLEAR MEDICINE |
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| Abstract | [Summary] Following the previous work, the coded aperture imaging using a rotating slit is investigated. In this method, the conventional pinhole is replaced by a slit aperture which is rotated continuously or stepwise around the center of the aperture. The decoding process is as follows : (1) images for various slit directions are accumulated separately in a digital computer ; (2) each of the images is spread (or smoothed) in the respective slit direction over a distance equal to the projected length of the slit on to the object plane ; (3) these images for all the directions are superimposed ; and (4) the obtained image is processed by a correction function so as to yield a Gaussian point spread function. A theoretical analysis for signal to noise ratio for an extended source shows that the gain in the figure of merit as compared to the equivalent pinhole is equal to 1.11√(2.35σ)/W, where 2.35σ is the resolution distance, W the slit width or the pinhole diameter scaled at the object plane, and the slit length is assumed to be sufficiently long. Images of the Picker thyroid phantom and of a patient thyroid were obtained with 99mTc using an Anger camera equipped with apertures of rotating slits and pinholes. The rotating slits employed are 2×10mm, and 2×15mm, while the pinholes are 2mmφ and 3mmφ. All images were processed to yield various resolutions and intercompared. The results show that the rotating slit gives the similar signal to noise ratio when the images are processed rather sharply and is a little better when processed broadly, as compared with the 2mmφ pinhole. It is also shown that the noise characteristics of the rotating slits are apparently different from those of the pinholes, but a further study on the effect of noise characteristics on the human recognition is needed before making a firm conclusion on the usefulness of the rotating slit. |
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| Practice | Clinical medicine |
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