心臓専用半導体SPECT装置における外部CTを用いた減弱補正法の効果

摘要

従来のアンガー型single photonemission computed tomography(SPECT)装置は，ヨウ化ナトリウム(sodiumiodide:NaI)シンチレータに入射したγ線を光子に変換し，光電子増倍管で増幅した後に電気信号として得られたデータを計算処理することで画像を作る(NaI-SPECT).一方，半導体SPECT装置はγ線をテルル化亜鉛カドミウム(cadmium zinc telluride:CdZnTe)の半導体検出器で直接電気信号に変換して画像を作る(CdZnTe-SPECT).そのため，CdZnTe-SPECTはNaI-SPECTと比較して著しく感度が増加し，空間分解能も向上でき，短時間収集でも同等の診断能が得られるとの報告がある.%The discovery of NM530c with a cadmium-zinc-telluride detector (CdZnTe-SPECT) is superior to the conventional Anger-type SPECT with a sodium-iodide detector (NaI-SPECT) in terms of sensitivity and spatial resolution. However, in the clinical example, even in CdZnTe-SPECT, a count decrease in myocardium due to the attenuation of the gamma ray is an issue. This study was conducted to evaluate the effect of computed tomography attenuation correction (CTAC) in CdZnTe-SPECT with the help of external CT. We evaluated the revision effect of uniformity, influence by the difference in attenuation distance, contrast ratio, an uptake rate using the heart phantom. As a result of the phantom studies, a good revision effect was obtained. In the clinical study, there was a statistical significant difference between the contrast ratio before and after CTAC in the inferior wall. In addition, the contrast ratio before and after CTAC in CdZnTe-SPECT image was equal to those of Nal-SPECT image. It was suggested that CTAC using external CT in CdZnTe-SPECT was clinically useful for inferior wall.