| Japanese |
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| Title | 頭部SPECT定量測定におけるコンプトン散乱線の影響 |
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| Subtitle | 原著 |
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| Authors | 飯田秀博*, 高橋正昭**, 本村信篤***, 蜂谷武憲*, 中川原譲二**** |
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| Authors(kana) | |
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| Organization | *秋田県立脳血管研究センター放射線医学研究部, **中村記念病院放射線科, ***東芝医用機器技術研究所, ****中村記念病院脳神経外科 |
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| Journal | 核医学 |
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| Volume | 33 |
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| Number | 2 |
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| Page | 143-151 |
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| Year/Month | 1996/2 |
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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」Single-photon emission computed tomographyを用いた定量測定におけるコンプトン散乱線の影響を評価した. 5種類のファントムおよび123I-IMPを用いた局所脳血流量の定量測定において, Ichihara-Ogawaらにより報告されたtriple-energy window法をゴールドスタンダードとして散乱線補正を行い, 局所放射能濃度の定量値の, 補正の有無による変化を計測した. 散乱線補正を行うと, 理論値の吸収減弱計数(μ値)(0.146cm-1)を用いた吸収補正により, 一様被写体の再構成画像は一様であり, また被写体の大きさを変化させても一定な定量値が得られた. また内部構造を持つ被写体についても, ほほ原放射能濃度分布どおりの定量画像を得ることができた. 一方, 散乱線補正を行わないで吸収補正のみを行うと, 一様であるべき被写体の内部が盛り上がり, また定量値は被写体の大きさおよび形状に依存した. この非一様性および大きさ依存性は, μ値を経験的に最適化(μ=0.07cm-1)することで押さえることができた. ただしその時, 内部構造のある被写体ではコントラストが低下し, したがって低カウント領域で過大評価, 高カウント領域では過小評価が認められた. 3Dホフマン脳ファントムおよび123I-IMPを用いた臨床検査では, 白質領域の過大評価は約20%程度, 灰白質の過小評価は局所脳血流量に依存し, 20-30%であった. この変化は散乱線含有量に依存し, したがって被写体の大きさ, 形, 放射能濃度の分布に依存すると考えられた. 今後さらに検討を行う必要があると考えられた. |
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| Practice | 臨床医学：一般 |
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| Keywords | Single-photon emission computed tomography, Quantification, Compton scatter, Cerebral blood flow. |
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| English |
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| Title | Effects of Compton Scatter in Quantitative Brain SPECT |
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| Subtitle | Original Articles |
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| Authors | Hidehiro IIDA*, Masaaki TAKAHASHI**, Nobuatsu MOTOMURA***, Takenori HACHIYA*, Jyoji NAKAGAWARA**** |
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| Authors(kana) | |
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| Organization | *Department of Radiology and Nuclear Medicine, Akita Research Institute for Brain and Blood Vessels, **Department of Radiology, Nakamura Memorial Hospital, ***Toshiba Medical Engineering Laboratory, Medical Equipment Division, ****Department of Neurosurgery, Nakamura Memorial Hospital |
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| Journal | The Japanese Journal of nuclear medicine |
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| Volume | 33 |
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| Number | 2 |
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| Page | 143-151 |
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| Year/Month | 1996/2 |
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| Article | Original article |
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| Publisher | THE JAPANESE SOCIETY OF NUCLEAR MEDICINE |
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| Abstract | [Summary]Effects of Compton scatter has been investigated for quantitative single-photon emission computed tomography. Using a technique proposed by Ichihara and Ogawa(triple-energy window method)as a gold standard, effects of correcting the scatter has been evaluated for 5 different phantom configurations, as well as a clinical cerebral blood flow study with use of 123I-IMP. Without the scatter correction but with a correction for attenuation, a conventional reconstruction provided a non-uniform distribution for uniform phantom configurations, and the quantitative pixel counts being highly dependent on size and shape of the objects. On the other hand, a uniform distribution and quantitative pixel counts that were independent of size or shape of the object were obtained by applying the scatter correction using a conventional attenuation correction technique with use of a theoretical μ value of 0.146 cm-1, thus suggesting importance of the scatter correction. Similar results were observed without the scatter correction, if an empirical value of μ of 0.07 cm-1 was used in the attenuation correction. However, this procedure was found to decrease the image contrast between the high count and low count regions. Significant underestimation of 20-30% was caused in cortical gray matter regions, and overestimation of 20% in the white matter regions. In practical clinical studies, magnitude of the error is still unknown, and is probably dependent on shape, size and radioactivity distribution of the object. A further systematic study is required in order to investigate significance of the scatter correction in real clinical studies. |
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| Practice | Clinical medicine |
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| Keywords | Single-photon emission computed tomography, Quantification, Compton scatter, Cerebral blood flow. |
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