title: Preliminary report on virtual monochromatic spectral imaging with fast kVp switching dual energy head CT: comparable image quality to that of 120-kVp CT without increasing the radiation dose.
abstract: OBJECTIVE
  This study aimed to evaluate whether the image quality of virtual monochromatic spectral imaging with fast kVp switching dual-energy CT (DECT) can be comparable to that of 120-kVp single-energy CT (SECT) without increasing the radiation dose.
  
  
  METHODS
  We retrospectively identified 15 postoperative patients who had undergone both DECT and 120-kVp SECT within a short period of time for follow-up after brain surgery. Simulated 65 keV monochromatic images were reconstructed from DECT data. Subjective image noise, gray-white matter contrast, and overall image quality were rated using a four-point scale. Quantitative measurement of noise, contrast-to-noise ratio (CNR), and posterior fossa beam-hardening artifact were also performed. The figure of merit (FOM), calculated as CNR(2)/CTDIvol, was used to quantify image quality improvement per exposure risk.
  
  
  RESULTS
  The mean CTDIvol was 70.2 ± 0.3 mGy for DECT, which was 11 % lower than SECT (78.9 ± 2.1 mGy). All images were graded above clinically acceptable. Quantitative and qualitative measures for simulated 65-keV images were comparable with SECT images, except for increase in subjective noise. FOM was significantly greater for simulated 65-keV images (P = .03).
  
  
  CONCLUSIONS
  Our results indicate that virtual monochromatic imaging possibly provides comparable image quality to that afforded by 120-kVp SECT without increasing the dose in routine head CT.
authors: Department of Radiology, National Center Hospital of Neurology and Psychiatry, Kodaira, Tokyo, 187-8551, Japan. kkamiya-tky@umin.ac.jp
authors: Kouhei
authors: K
authors: Kamiya
authors: Akira
authors: A
authors: Kunimatsu
authors: Harushi
authors: H
authors: Mori
authors: Jiro
authors: J
authors: Sato
authors: Masaaki
authors: M
authors: Akahane
authors: Takana
authors: T
authors: Yamakawa
authors: Kuni
authors: K
authors: Ohtomo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014584:User-Computer Interface