Iguchi Harumi, Kida Tetsuo, Noma Kazuo, Yoshimura Masahiro, Hamazu Masanari, Masuda Kazutaka
Department of Radiology, Shiga University of Medical Science.
Nihon Hoshasen Gijutsu Gakkai Zasshi. 2006 Jun 20;62(6):840-7. doi: 10.6009/jjrt.62.840.
Attenuation correction is necessary for the reconstruction of SPECT images. One report has mentioned that attenuation correction by X-ray computed tomography (CT) is effective for a non-uniform attenuation body. We examined the effect of attenuation correction on SPECT images by changing the scanning conditions of CT, and evaluated the possibility of attenuation correction by low-dose CT. The phantom was scanned under several X-ray tube conditions varying from 80 kV to 135 kV and from 7.5 mAs to 200 mAs. We obtained equations of attenuation correction based on the Hounsfield Unit (HU) units of each pixel and compared the effects of attenuation correction. The results showed that the equation for attenuation correction under each condition did not vary significantly, and the effects of attenuation correction by the equations did not vary significantly between CT of low dose and that of clinical dose. This result suggest that the attenuation correction obtained by low-dose CT was equal to that obtained by the clinical dose. In conclusion, it seemed that the equation and map of attenuation correction matched with each radionuclide yielded more adequate attenuation correction than conventional methods.
衰减校正是单光子发射计算机断层扫描（SPECT）图像重建所必需的。一份报告提到，通过X射线计算机断层扫描（CT）进行衰减校正对于非均匀衰减体是有效的。我们通过改变CT的扫描条件来研究衰减校正对SPECT图像的影响，并评估低剂量CT进行衰减校正的可能性。在几种X射线管条件下对体模进行扫描，管电压范围为80 kV至135 kV，管电流时间积范围为7.5 mAs至200 mAs。我们基于每个像素的亨氏单位（HU）获得了衰减校正方程，并比较了衰减校正的效果。结果表明，每种条件下的衰减校正方程没有显著差异，低剂量CT和临床剂量CT通过这些方程进行衰减校正的效果也没有显著差异。这一结果表明，低剂量CT获得的衰减校正与临床剂量获得的衰减校正相当。总之，与传统方法相比，似乎与每种放射性核素匹配的衰减校正方程和图谱能产生更合适的衰减校正。
