中国物理B ›› 2014, Vol. 23 ›› Issue (2): 27802-027802.doi: 10.1088/1674-1056/23/2/027802

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

A generalized method of converting CT image to PET linear attenuation coefficient distribution in PET/CT imaging

王璐a b, 武丽伟a b, 魏乐a b, 高娟a c, 孙翠丽a c, 柴培a c, 李道武a c   

  1. a Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China;
    b University of Chinese Academy of Sciences, Beijing 100049, China;
    c Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing 100049, China
  • 收稿日期:2013-04-19 修回日期:2013-05-24 出版日期:2013-12-12 发布日期:2013-12-12
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 81101070 and 81101175).

A generalized method of converting CT image to PET linear attenuation coefficient distribution in PET/CT imaging

Wang Lu (王璐)a b, Wu Li-Wei (武丽伟)a b, Wei Le (魏乐)a b, Gao Juan (高娟)a c, Sun Cui-Li (孙翠丽)a c, Chai Pei (柴培)a c, Li Dao-Wu (李道武)a c   

  1. a Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China;
    b University of Chinese Academy of Sciences, Beijing 100049, China;
    c Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing 100049, China
  • Received:2013-04-19 Revised:2013-05-24 Online:2013-12-12 Published:2013-12-12
  • Contact: Chai Pei E-mail:chaipei@ihep.ac.cn
  • About author:78.70.-g; 87.57.uk; 87.59.Q-; 87.57.C-
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 81101070 and 81101175).

摘要: The accuracy of attenuation correction in positron emission tomography scanners depends mainly on deriving the reliable 511-keV linear attenuation coefficient distribution in the scanned objects. In the PET/CT system, the linear attenuation distribution is usually obtained from the intensities of the CT image. However, the intensities of the CT image relate to the attenuation of photons in an energy range of 40 keV–140 keV. Before implementing PET attenuation correction, the intensities of CT images must be transformed into the PET 511-keV linear attenuation coefficients. However, the CT scan parameters can affect the effective energy of CT X-ray photons and thus affect the intensities of the CT image. Therefore, for PET/CT attenuation correction, it is crucial to determine the conversion curve with a given set of CT scan parameters and convert the CT image into a PET linear attenuation coefficient distribution. A generalized method is proposed for converting a CT image into a PET linear attenuation coefficient distribution. Instead of some parameter-dependent phantom calibration experiments, the conversion curve is calculated directly by employing the consistency conditions to yield the most consistent attenuation map with the measured PET data. The method is evaluated with phantom experiments and small animal experiments. In phantom studies, the estimated conversion curve fits the true attenuation coefficients accurately, and accurate PET attenuation maps are obtained by the estimated conversion curves and provide nearly the same correction results as the true attenuation map. In small animal studies, a more complicated attenuation distribution of the mouse is obtained successfully to remove the attenuation artifact and improve the PET image contrast efficiently.

关键词: linear attenuation coefficient, PET/CT, attenuation correction, consistency conditions

Abstract: The accuracy of attenuation correction in positron emission tomography scanners depends mainly on deriving the reliable 511-keV linear attenuation coefficient distribution in the scanned objects. In the PET/CT system, the linear attenuation distribution is usually obtained from the intensities of the CT image. However, the intensities of the CT image relate to the attenuation of photons in an energy range of 40 keV–140 keV. Before implementing PET attenuation correction, the intensities of CT images must be transformed into the PET 511-keV linear attenuation coefficients. However, the CT scan parameters can affect the effective energy of CT X-ray photons and thus affect the intensities of the CT image. Therefore, for PET/CT attenuation correction, it is crucial to determine the conversion curve with a given set of CT scan parameters and convert the CT image into a PET linear attenuation coefficient distribution. A generalized method is proposed for converting a CT image into a PET linear attenuation coefficient distribution. Instead of some parameter-dependent phantom calibration experiments, the conversion curve is calculated directly by employing the consistency conditions to yield the most consistent attenuation map with the measured PET data. The method is evaluated with phantom experiments and small animal experiments. In phantom studies, the estimated conversion curve fits the true attenuation coefficients accurately, and accurate PET attenuation maps are obtained by the estimated conversion curves and provide nearly the same correction results as the true attenuation map. In small animal studies, a more complicated attenuation distribution of the mouse is obtained successfully to remove the attenuation artifact and improve the PET image contrast efficiently.

Key words: linear attenuation coefficient, PET/CT, attenuation correction, consistency conditions

中图分类号:  (Interactions of particles and radiation with matter)

  • 78.70.-g
87.57.uk (Positron emission tomography (PET)) 87.57.C- (Image quality)