The present invention is directed towards spectral imaging, wherein a dedicated spectral imaging phantom is scanned with a spectral x-ray device to obtain spectral imaging data of the spectral imaging phantom. Said imaging data of the spectral imaging phantom is used as input for obtaining improved further imaging data of a subject of which a spectral scan is performed subsequent to or simultaneous with the spectral scan of the spectral imaging phantom. Improved further imaging data may be obtained by using the spectral phantom imaging data as input for imaging data correction, for providing a recommendation and/or for further data processing.