title: [Investigation on the 3 D geometric accuracy and on the image quality (MTF, SNR and NPS) of volume tomography units (CT, CBCT and DVT)].
abstract: OBJECTIVE
  The study aims at investigating how far image quality (MTF and NPS) differs in between CT, CBCT and DVT units and how far the geometrical 3 D accuracy and the HU calibration differ in respect to surgical or radio therapeutic planning.
  
  
  METHODS
  X ray image stacks have been made using a new designed test device which contains structures for measuring MTF, NPS, the 3 D accuracy and the Hounsfield calibration (jaw or skull program). The image stacks of the transversal images were analyzed with a dedicated computer program.
  
  
  RESULTS
  The MTF values are correlated with the physical resolution (CT and DVT) and are influenced by the used Kernel (CT). The NPS values are limited to an intra system comparison due to the insufficient HU accuracy. The 3 D accuracy is comparable in between the system types.
  
  
  CONCLUSIONS
  The values of image quality are not yet correlated with dose values: NPS. Investigations to an appropriate dosimetry are ongoing to establish the ratio between dose and image quality (ALARA principle). No fundamental difference between the systems can be stated in respect radio therapeutic planning: improper HU calibration accuracy in CBCT and DVT units. The geometric 3 D accuracy of high performance DVT systems is greater than that of CT Systems.
authors.affiliation: Institute for Media and Imaging Technology, Cologne University pf Applied Sciences. christian.blendl@fh-koeln.de
authors.forename: C
authors.initials: C
authors.lastname: Blendl
authors.forename: M
authors.initials: M
authors.lastname: Fiebich
authors.forename: J M
authors.initials: JM
authors.lastname: Voigt
authors.forename: M
authors.initials: M
authors.lastname: Selbach
authors.forename: C
authors.initials: C
authors.lastname: Uphoff
mesh_terms: D016477:Artifacts; D002138:Calibration; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation / Q000592:standards*; D005583:Fourier Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation / Q000592:standards*; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000592:standards*; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000592:standards*; D019047:Phantoms, Imaging; D011785:Quality Assurance, Health Care / Q000592:standards*; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000592:standards; D011881:Radiotherapy, Computer-Assisted / Q000295:instrumentation / Q000592:standards; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000592:standards; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000592:standards*