| Japanese |
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| Title | 荷重逆投影法によるシングルフォトンECT画像の雑音特性 |
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| Subtitle | 原著 |
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| Authors | 村山秀雄*, 田中栄一*, 外山比南子** |
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| Organization | *放射線医学総合研究所物理研究部, **東京都養育院附属病院核医学放射線部 |
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| Journal | 核医学 |
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| Volume | 22 |
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| Number | 3 |
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| Page | 307-319 |
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| Year/Month | 1985/3 |
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| Article | 原著 |
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| Publisher | 日本核医学会 |
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| Abstract | 「要旨」荷重逆投影法によるシングルフォトンECT画像の統計的雑音を評価するための計算式を求めた. 単純な線源分布を仮定した数学的ファントムに対してこの計算式を適用し, 再構成画像の雑音特性を分析した. 統計的雑音の性質が, ガンマ線の減弱係数, 被検体の大きさ, 線源分布および再構成指数に依存し, また, 座標原点の位置により雑音特性が変化することを2次元雑音分布像で示した. 計算機シミュレーションによってポアッソン雑音を含む投影データを作成し, 荷重逆投影法および他のいくつかの吸収補正法に対する再構成画像と, その2次元雑音分布像をそれぞれ鳥かん図で表示し, それらの画像の比較を行った. その結果, 荷重逆投影法が再構成画像の歪みおよび雑音の小さい吸収補正法であることが明らかとなった. |
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| Practice | 臨床医学：一般 |
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| Keywords | Single photon emission computed tomography, Attenuation correction, Statistical noise in SPECT images, Computer simulation, Weighted backprojection |
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| English |
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| Title | Statistical Noise with the Weighted Backprojection Method for Single Photon Emission Computed Tomography |
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| Subtitle | Original Articles |
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| Authors | Hideo MURAYAMA*, Eiichi TANAKA*, Hinako TOYAMA** |
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| Organization | *Division of Physics, National Institute of Radiological Sciences, **Tokyo Metropolitan Geriatric Hospital |
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| Journal | The Japanese Journal of nuclear medicine |
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| Volume | 22 |
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| Number | 3 |
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| Page | 307-319 |
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| Year/Month | 1985/3 |
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| Article | Original article |
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| Publisher | THE JAPANESE SOCIETY OF NUCLEAR MEDICINE |
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| Abstract | [Summary] The weighted backprojection (WBP) method and the radial post-correction (RPC) method were compared with other several attenuation correction methods for single photon emission computed tomography by computer simulation. These methods are the pre-correction method with arithmetic means of opposing projections, the post-correction method with a correction matrix, and the inverse attenuated Randon transform method. Statistical mean square noise in a reconstructed image was formulated, and was displayed two-dimensionally for typical simulated phantoms. The noise image for the WBP method was dependent on several parameters, namely, size of an attenuating object, distribution of activity, the attenuation coefficient, and choise of the reconstruction index, k and position of the reconstruction origin. The noise image for the WBP method with k=0 was almost the same for the RPC method. It has been shown that position of the reconstruction origin has to be chosen appropriately in order to improve the noise properties of the reconstructed image for the WBP method as well as the RPC method. Comparision of the different attenuation correction methods accomplished by using both the reconstructed images and the statistical noise images with the same mathematical phantom and convolving function concluded that the WBP method and the RPC method were more amenable to any radioisotope distributions than the other methods, and had the advantage of flexibility to improve image noise of any local positions. |
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| Practice | Clinical medicine |
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| Keywords | Single photon emission computed tomography, Attenuation correction, Statistical noise in SPECT images, Computer simulation, Weighted backprojection |
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