title: Effective doses in subjects undergoing computed tomography cardiac imaging with the 256-multislice CT scanner.
abstract: BACKGROUND
  The 256-multislice CT (256MSCT) obtains volumetric data with 128-mm coverage in a single rotation. This coverage allows satisfactory visualization of the whole heart, allowing the 256MSCT to visualize the cardiac chambers and coronary arteries by cine scan without ECG gating. These characteristics provide a solution to the problems of MSCT. Although a wider beam width provides more efficient imaging over a wider coverage area, patient doses with the 256MSCT are of considerable concern.
  
  
  OBJECTIVE
  We assessed potential radiation exposure with the 256MSCT in a cardiac CT protocol and compared the results to those with 16- and 64MSCT (collimated 64x0.5mm using 256MSCT).
  
  
  METHODS
  Organ or tissue doses were measured in an anthropomorphic phantom under a coronary artery imaging protocol with the 256MSCT in cine scan mode without ECG gating, and with the 16- and 64MSCT in helical scan mode with ECG gating.
  
  
  RESULTS
  Average effective doses were 22.8mSv for the 16MSCT, 27.8mSv for the 64MSCT and 14.1mSv for the 256MSCT. The 16- and 64MSCT doses were thus approximately 1.6- and 2.0-fold higher than those of the 256MSCT.
  
  
  CONCLUSIONS
  Use of the 256MSCT in cardiac volumetric cine imaging offers lower radiation exposure than 16- and 64MSCT, and suggests the potential of this equipment in single-beat cardiac imaging without ECG gating. This effective dose is acceptable for routine cardiac imaging.
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Mori
authors.forename: Kanae
authors.initials: K
authors.lastname: Nishizawa
authors.forename: Chisato
authors.initials: C
authors.lastname: Kondo
authors.forename: Mari
authors.initials: M
authors.lastname: Ohno
authors.forename: Keiichi
authors.initials: K
authors.lastname: Akahane
authors.forename: Masahiro
authors.initials: M
authors.lastname: Endo
mesh_terms: D017023:Coronary Angiography / Q000379:methods*; D006801:Humans; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*