title: A positron emission tomography/computed tomography (PET/CT) acquisition protocol for CT radiation dose optimization.
abstract: BACKGROUND
  In current combined positron emission tomography/computed tomography (PET/CT) systems, high-quality CT images not only increase diagnostic value by providing anatomic delineation of hyper- and hypometabolic tissues, but also shorten the acquisition time for attenuation correction compared with standard PET imaging. However, this technique potentially introduces more radiation burden to patients as a result of the higher radiation exposure from CT.
  
  
  METHODS
  In this study, the radiation doses delivered from typical germanium-based and CT-based transmission scans were measured and compared using an anthropomorphic Rando Alderson phantom with insertions of thermoluminescent dosimeters. Image geometric distortion and quantified uptake values in PET images with different manipulating CT acquisition protocols for attenuation correction were also evaluated.
  
  
  RESULTS
  It was found that radiation doses during germanium-based transmission scans were almost negligible, while doses from CT-based transmission scans were significantly higher. Using a lower radiation dose, the CT acquisition protocol did not significantly affect attenuation correction and anatomic delineation in PET.
  
  
  CONCLUSIONS
  This study revealed the relation between image information and dose. The current PET/CT imaging acquisition protocol was improved by decreasing the radiation risks without sacrificing the diagnostic values.
authors.affiliation: Institute of Radiological Sciences, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Tung-Hsin
authors.initials: TH
authors.lastname: Wu
authors.forename: Tieh-Chi
authors.initials: TC
authors.lastname: Chu
authors.forename: Yung-Hui
authors.initials: YH
authors.lastname: Huang
authors.forename: Liang-Kung
authors.initials: LK
authors.lastname: Chen
authors.forename: Seng-Peng
authors.initials: SP
authors.lastname: Mok
authors.forename: Jong-Kang
authors.initials: JK
authors.lastname: Lee
authors.forename: Tyan
authors.initials: T
authors.lastname: Yeu-Sheng
authors.forename: Jason J S
authors.initials: JJ
authors.lastname: Lee
mesh_terms: D001822:Body Burden; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D012062:Relative Biological Effectiveness; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*