X-ray imaging data processing device and method

1. A medical device for processing data in X-ray images to reduce vibration artifacts in differential phase contrast imaging, comprising:

a processor configured to provide a proportionality factor between an object induced phase shift for a first x-ray energy bin and an object induced phase shift for a second x-ray energy bin, and

determine at least one of a dark field signal and an object induced phase shift from a detected intensity value of a pixel for the first energy bin and a detected intensity value of the pixel for the second energy bin using the proportionality factor.

2. The medical device according to claim 1 , wherein the proportionality factor is dependent on a first attenuation value for the first energy bin and a second attenuation value for the second energy bin.

3. The medical device according to claim 2 , further comprising a look-up table that includes the first and second attenuation values and the proportionality factor.

4. The medical device according to claim 1 , wherein first attenuation value for the first energy bin, a second attenuation value for the second energy bin, a first dark field signal for the first energy bin, a second dark field signal for the second energy bin, an object induced phase shift and a disturbance induced phase shift are determined based on measured data of the first and second energy bins in such way that a likelihood obtaining the measured data is maximized.

5. The medical device according to claim 1 , wherein the processor is configured to use a least square minimization equation.

6. The medical device according to claim 1 , wherein the dark field and phase shift determining unit is arranged to include, in the determination, a further limitation as to favor small differences between disturbance induced phase shifts of neighboring pixels.

7. The medical device according to claim 1 , wherein the processor is further configured to:

using the first energy bin to calculate a first phase shift for the first energy bin from a phase image obtained by differential phase contrast x-ray imaging a phantom that has a predetermined shape;

using the second energy bin to calculate a second phase shift for the second energy bin from the phase image obtained by differential phase contrast x-ray imaging the phantom; and

obtain the proportionality factor from the first phase shift and the second phase shift.

8. The medical device according to claim 7 , wherein the phantom includes a plurality of portions, each portion having a height changing in a direction transverse to a beam direction of an X-ray, and wherein different portions of the phantom have different average heights.

9. A differential phase contrast x-ray imaging system, comprising:

a differential phase contrast imaging unit;

an x-ray source arranged to provide x-rays of a first and a second energy bin; and

a medical device for processing data in X-ray images to reduce vibration artifacts in differential phase contrast imaging, comprising:

a processor configured to provide a proportionality factor between an object induced phase shift for a first x-ray energy bin and an object induced phase shift for a second x-ray energy bin, and determine at least one of a dark field signal and an object induced phase shift from a detected intensity value of a pixel for the first energy bin and a detected intensity value of the pixel for the second energy bin using the proportionality factor.

10. A method for processing data in X-ray images of a medical device to reduce vibration artifacts in differential phase contrast imaging, comprising:

providing a proportionality factor between an object induced phase shift for a first x-ray energy bin and an object induced phase shift for a second x-ray energy bin; and

determining at least one of a dark field signal and an object induced phase shift from a detected intensity value of a pixel for the first energy bin and a detected intensity value of the pixel for the second energy bin using the proportionality factor.

11. The method of claim 10 , further comprising:

using the first energy bin to calculate a first phase shift for the first energy bin from a phase image obtained by differential phase contrast x-ray imaging a phantom having a predetermined shape;

using the second energy bin to calculate a second phase shift for the second energy bin from a phase image obtained by differential phase contrast x-ray imaging the phantom; and

obtaining the proportionality factor from the first phase shift and the second phase shift.