title: Comparison of five methods for the derivation of spectra for a constant potential dental X-ray unit.
abstract: OBJECTIVE
  To compare the diagnostic X-ray spectra derived by different methods for a constant potential dental X-ray unit.
  
  
  METHODS
  Five methods of deriving X-ray spectra for a constant potential dental X-ray unit were compared: measurement by spectrometer using cadmium-zinc-telluride (CZT) detector, calculation by Monte Carlo simulation, calculation by two different, semi-empirical methods and estimation from transmission data. The dental X-ray set was a Heliodent MD unit (Sirona, Charlotte, NC, USA) operable at 60 or 70 kV. A semiconductor detector was used in the spectrometer measurements and an ionization chamber dosimeter in the transmission measurements. From the five methods, photon-fluence spectra were derived. Based on the photon-fluence spectra, average energies and transmission curves in aluminum were calculated.
  
  
  RESULTS
  For all five methods, the average energies were within 2.4% of one another. Comparison of the transmission curves showed an average difference in the range of 1 to 6%.
  
  
  CONCLUSIONS
  All of the five methods of deriving spectra are in extremely good agreement with each other.
authors.affiliation: University of Texas Health Science Center, San Antonio, Texas 78284-7919, USA.
authors.forename: B R
authors.initials: BR
authors.lastname: Lankipalli
authors.forename: W D
authors.initials: WD
authors.lastname: McDavid
authors.forename: S B
authors.initials: SB
authors.lastname: Dove
authors.forename: E
authors.initials: E
authors.lastname: Wieckowska
authors.forename: R G
authors.initials: RG
authors.lastname: Waggener
authors.forename: J R
authors.initials: JR
authors.lastname: Mercier
mesh_terms: D000465:Algorithms; D000535:Aluminum; D002104:Cadmium; D002138:Calibration; D006801:Humans; D009010:Monte Carlo Method; D017785:Photons; D011829:Radiation Dosage; D011861:Radiography, Dental / Q000295:instrumentation* / Q000592:standards; D011874:Radiometry; D012666:Semiconductors; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods; D013691:Tellurium; D014965:X-Rays; D015032:Zinc
chemical_list: D002104:Cadmium; D000535:Aluminum; D015032:Zinc; D013691:Tellurium