| Japanese |
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| Title | 投影データのパワースペクトルから設計したSPECT画像復元フィルタについて |
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| Subtitle | 原著 |
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| Authors | 久保直樹* |
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| Organization | *北海道大学医療技術短期大学部診療放射線技術学科 |
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| Journal | 核医学 |
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| Volume | 32 |
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| Number | 4 |
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| Page | 395-403 |
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| Year/Month | 1995/4 |
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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」SPECT画像を改善するため新しい復元フィルタの設計方法を開発した. この方法は最小2乗フィルタの理論を応用し, そこで用いる信号スペクトル強度および雑音スペクトル強度を, 投影データから作成したパワースペクトルの高周波部分を指数関数の多項式で近似することで推定した. このフィルタをバターワースフィルタ (0.15 cycles/pixelの遮断周波数) およびウィナーフィルタ (信号/雑音スペクトル強度比が定数) と比較した. 99mTcを封入した円筒内に2本の線源を並べたファントムを用いて評価した. Normalized mean-squared errorを求めるとバターワースフィルタは0.77, ウィナーフィルタは0.83, パワースペクトルから設計したフィルタは0.76であった. 脳血流SPECTに応用した場合, コントラストが改善した. このように本設計法によるフィルタは臨床的に有効であろうと考えられる. |
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| Practice | 臨床医学：一般 |
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| Keywords | SPECT, Restoration filter, Wiener filter, Butterworth filter, Power spectrum |
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| English |
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| Title | Restoration Filtering Based on Projection Power Spectrum for Single-Photon Emission Computed Tomography |
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| Subtitle | |
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| Authors | Naoki KUBO |
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| Authors(kana) | |
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| Organization | Department of Radiological Technology, College of Medical Technology, Hokkaido University |
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| Journal | The Japanese Journal of nuclear medicine |
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| Volume | 32 |
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| Number | 4 |
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| Page | 395-403 |
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| Year/Month | 1995/4 |
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| Article | Original article |
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| Publisher | THE JAPANESE SOCIETY OF NUCLEAR MEDICINE |
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| Abstract | [Summary] To improve the quality of single-photon emission computed tomographic (SPECT) images, a restoration filter has been developed. This filter was designed according to practical "least squares filter" theory. It is necessary to know the object power spectrum and the noise power spectrum. The power spectrum is estimated from the power spectrum of a projection, when the high-frequency power spectrum of a projection is adequately approximated as a polynomial exponential expression. A study of the restoration with the filter based on a projection power spectrum was conducted, and compared with that of the "Butterworth" filtering method (cut-off frequency of 0.15 cycles/pixel), and "Wiener" filtering (signal-to-noise power spectrum ratio was a constant). Normalized mean-squared errors (NMSE) of the phantom, two line sources located in a 99mTc filled cylinder, were used. NMSE of the "Butterworth" filter, "Wiener" filter, and filtering based on a power spectrum were 0.77, 0.83, and 0.76 respectively. Clinically, brain SPECT images utilizing this new restoration filter improved the contrast. Thus, this filter may be useful in diagnosis of SPECT images. |
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| Practice | Clinical medicine |
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| Keywords | SPECT, Restoration filter, Wiener filter, Butterworth filter, Power spectrum |
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