Energy calibration by simultaneous model-fitting to threshold scans for several kVp
2016 (English)Article in journal (Other academic) Submitted
Accurate calibration of the energy thresholds on spectral x-ray detectors used for computed tomography is essential for avoiding ring artifacts and bias when using basis material decomposition. Previously, it has been proposed to calibrate the energy thresholds by fitting simulated data to a threshold scan of a polychromatic spectrum from a medical x-ray tube. Here, we suggest that the energy calibration is performed by fitting simulated data to threshold scans acquired at several different kVp settings simultaneously. The method is evaluated experimentally by its capacity to correctly position the noise floor and the k-edge of tungsten. It is shown that using several kVp settings largely improves the accuracy of the energy calibration, particularly in the low energy range. Since the method only relies on the spectra from the x-ray tube (without any specific filtration), it is ideal for the use in a clinical computed tomography system. It is also shown that the method can operate with a fairly low number of detected photons, whichis promising in terms of calibration time.
Place, publisher, year, edition, pages
Accelerator Physics and Instrumentation
Research subject Medical Technology
IdentifiersURN: urn:nbn:se:kth:diva-195017OAI: oai:DiVA.org:kth-195017DiVA: diva2:1043880
QCR 201611032016-11-012016-11-012016-11-22Bibliographically approved