| Zugriffsnummer | 37841 |
| Dokumenttyp | Konferenzartikel in Zeitschrift |
| Peer Review | mit Peer Review |
| Sprache | Englisch |
| Titel | X-ray spectrum dependence of the magnification of cone-beam CT |
| Autor(in); Institution |
Illemann, Jens; 5.3, Koordinatenmesstechnik, PTB-Braunschweig
Bartscher, Markus; 5.3, Koordinatenmesstechnik, PTB-Braunschweig
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| Quelle/Jahr | 7th Conference on Industrial Computed Tomography (iCT) 2017: proceedings. Journal of Nondestructive Testing and Ultrasonics:(2017), 1 - 12 |
| Availability | [online only] |
| ISSN | 1435-4934 |
| URL | |
| Verlag | Bad Breisig: NDT |
| Konferenzangaben | 7th Conference on Industrial Computed Tomography (iCT 2017), Leuven, 07-09, February, 2017, Belgium |
| Freie Schlagworte | cone-beam CT ; scintillator ; magnification ; geometrical model ; material dependence |
| Zusammenfassung | Modern industrial computed tomography (CT) scanners mainly use flat-panel detectors (FPD) in cone-beam geometry. All CT length measurements rely on knowledge of geometrical magnification. To date, it is been assumed that this is invariant, and that a calibration measurement therefore can be applied to determine the voxel size. The magnification is determined by the ratio of the effective distance of the source to the object and that of the source to the detector. The scintillator of FPDs is frequently made of structured CsI with a thickness of about 600 μm. For photon energies varying from 20 keV to 80 keV, the photon’s mean penetration depth varies from 80 νm to 600 μm. The magnification can thus change relatively - depending on the voltage, filter and object material - by some 10-4. Additional effects of this size arise from the X-ray spectrum’s change over the source’s spot area. This paper presents experimental data for the X-ray-spectrum-dependent effective magnification of a cone-beam CT system and demonstrates the relevance of the effects as one limit for dimensional CT. |
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