title: Variation in tube voltage for adult neck MDCT: effect on radiation dose and image quality.
abstract: OBJECTIVE
  The purpose of this study was to assess the effect of peak kilovoltage on radiation dose and image quality in adult neck MDCT.
  
  
  METHODS
  An anthropomorphic phantom with metal oxide semiconductor field effect transistor detectors was imaged with a 64-MDCT scanner. The reference CT protocol called for 120 kVp, and images obtained with that protocol were compared with CT images obtained with protocols entailing 80, 100, and 140 kVp. All imaging was performed with automatic tube current modulation. Organ dose and effective dose were determined for each protocol and compared with those obtained with the 120-kVp protocol. Image noise was evaluated objectively and subjectively for each protocol.
  
  
  RESULTS
  The highest organ doses for all protocols were to the thyroid, ocular lens, skin, and mandible. The greatest reductions in organ dose were for the bone marrow of the cervical spine and mandible: 43% and 35% with the 100-kVp protocol and 63% and 53% with the 80-kVp protocol. Effective dose decreased as much as 9% with the 100-kVp protocol and 12% with the 80-kVp protocol. Use of the 140-kVp protocol was associated with an increase in organ dose as high as 64% for bone marrow in the cervical spine and a 19% increase in effective dose. Image noise increased with lower peak kilovoltage. The measured noise difference was greatest at 80 kVp, absolute increases were less than 2.5 HU. There was no difference in subjective image quality among protocols.
  
  
  CONCLUSIONS
  Reducing the voltage from 120 to 80 kVp for neck CT can result in greater than 50% reduction in the absorbed organ dose to the bone marrow of the cervical spine and mandible without impairment in subjective image quality.
authors.affiliation: Department of Radiology, Duke University Medical Center, Box 3808, Erwin Rd, Durham, NC 27710, USA. jennykh@gmail.com
authors.forename: Jenny K
authors.initials: JK
authors.lastname: Hoang
authors.forename: Terry T
authors.initials: TT
authors.lastname: Yoshizumi
authors.forename: Giao
authors.initials: G
authors.lastname: Nguyen
authors.forename: Greta
authors.initials: G
authors.lastname: Toncheva
authors.forename: Kingshuk Roy
authors.initials: KR
authors.lastname: Choudhury
authors.forename: Andreia R
authors.initials: AR
authors.lastname: Gafton
authors.forename: James D
authors.initials: JD
authors.lastname: Eastwood
authors.forename: Carolyn
authors.initials: C
authors.lastname: Lowry
authors.forename: Lynne M
authors.initials: LM
authors.lastname: Hurwitz
mesh_terms: D000328:Adult; D006801:Humans; D009333:Neck / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011835:Radiation Protection; D011857:Radiographic Image Interpretation, Computer-Assisted; D012016:Reference Values; D036542:Tomography, Spiral Computed / Q000379:methods*