title: The feasibility of low-dose CT protocols for coronary artery calcium scoring and PET attenuation correction in cardiac PET/CT.
abstract: BACKGROUND
  The purpose of this study was to investigate the feasibility of using low-dose computed tomography (CT) in coronary artery calcium scoring and PET attenuation correction for patients in different weight categories undergoing cardiac PET/CT examinations.
  
  
  METHODS
  Calcium scoring computed tomography (CSCT) scans and PET scans of anthropomorphic cardiac phantoms simulating normal-weight, mildly obese, and severely obese patients were acquired with a hybrid PET/CT scanner. CSCT images were acquired at 120 kVp, with tube current ranging from 10 to 550 mA. PET scans were performed in three-dimensional mode, with acquisition time of 3 min/bed position. The image quality of cardiac PET/CT was evaluated by assessing the signal-to-noise ratio. CT-based coronary artery calcium quantification was performed using the Agatston scoring system.
  
  
  RESULTS
  On the basis of our results, the CSCT protocols using tube currents of 50 and 150 mA should be able to achieve the lowest possible radiation dose while maintaining the desired image quality for normal-weight and mildly obese patients undergoing cardiac PET/CT examinations, respectively. When the proposed low-dose CSCT protocols were performed, radiation dose could be reduced by 83.34 and 50% compared with those from CSCT scans acquired with standard tube current settings for normal-weight and mildly obese patients, respectively. In the scanning of severely obese patients, an increase in tube voltage or current would help improve the reliability of image information provided by cardiac PET/CT.
  
  
  CONCLUSIONS
  Our study demonstrated the feasibility of low-dose CT protocols for coronary artery calcium scoring and PET attenuation correction in cardiac PET/CT to examine patients in different weight categories. The calculations performed in this work should be able to provide practical information to achieve necessary diagnostic information while keeping radiation dose as low as reasonably achievable.
authors.affiliation: aDepartment of Biomedical Imaging and Radiological Sciences, National Yang Ming University bDepartment of Radiology, Shin Kong Wu Ho-Su Memorial Hospital cDepartment of Nuclear Medicine, Taipei Veterans General Hospital, Taipei dDepartment of Medical Imaging and Radiological Sciences, Tzu-Chi College of Technology, Hualien, Taiwan, ROC eBiomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau, China.
authors.forename: Tung-Hsin
authors.initials: TH
authors.lastname: Wu
authors.forename: Kun-Mu
authors.initials: KM
authors.lastname: Lu
authors.forename: Nien-Yun
authors.initials: NY
authors.lastname: Wu
authors.forename: Shyh-Jen
authors.initials: SJ
authors.lastname: Wang
authors.forename: Greta S P
authors.initials: GS
authors.lastname: Mok
authors.forename: Bang-Hung
authors.initials: BH
authors.lastname: Yang
authors.forename: Ching-Ching
authors.initials: CC
authors.lastname: Yang
mesh_terms: D002118:Calcium / Q000378:metabolism*; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000378:metabolism*; D005240:Feasibility Studies; D019788:Fluorodeoxyglucose F18; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D064847:Multimodal Imaging; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18; D002118:Calcium