Calculation device for determining ventilation defects
The present invention relates to a calculation device ( 10 ) for comparing dark-field X-ray images. The calculation device in ( 10 ) is configured for receiving a first dark-field X-ray image ( 11 ) describing first dark-field X-ray signals of a patient at an expiration state and for receiving a second dark-field X-ray image ( 12 ) describing second dark-field X-ray signals of the patient at an inspiration state. The calculation device is further ( 10 ) configured for normalizing the first dark-field X-ray signals of the first dark-field X-ray tin image ( 11 ) with a lung thickness value describing the lung thickness at the expiration state and for normalizing the second dark-field X-ray signals of the second dark-field X-ray image ( 12 ) with a lung thickness value describing the lung thickness at the inspiration state. Further, the calculation device ( 10 ) is configured for comparing the normalized first dark-field X-ray signals with the normalized second dark-field X-ray signals, thereby determining a comparison result ( 13 ) and for determining whether at least one area of the patient's lung with a ventilation defect exists based on the comparison result ( 13 ).
1. A calculation device for comparing dark-field X-ray images, comprising:
a storage memory configured to store instructions; and
processing circuitry for executing the instructions to:
receive a first dark-field X-ray image describing first dark-field X-ray signals of a patient at an expiration state;
receive a second dark-field X-ray image describing second dark-field X-ray signals of the patient at an inspiration state;
normalize the first dark-field X-ray signals of the first dark-field X-ray image with a lung thickness value describing the lung thickness at the expiration state;
normalize the second dark-field X-ray signals of the second dark-field X-ray image with a lung thickness value describing the lung thickness at the inspiration state;
compare the normalized first dark-field X-ray signals with the normalized second dark-field X-ray signals, thereby determining a comparison result; and
determine whether at least one area of the patient's lung with a ventilation defect exists based on the comparison result.
2. The calculation device according to claim 1 , further configured to identify at least one area of the patient's lung with the ventilation defect based on the comparison result.
3. The calculation device according to claim 1 , further configured to perform a registration of the normalized first and second dark-field X-ray images.
4. The calculation device according to claim 1 , further configured to smooth the normalized first dark-field X-ray signals and the normalized second dark-field X-ray signals.
5. The calculation device according to claim 1 , further configured to calculate a ratio between the normalized first dark-field X-ray signals and the normalized second dark-field X-ray signals for comparing the normalized first dark-field X-ray signals with the normalized second dark-field X-ray signals, and to determine whether the at least one area of the patient's lung with the ventilation defect exists, if the calculated ratio is close to 1.
6. The calculation device according to claim 1 , further configured to calculate a difference between the normalized first dark-field X-ray signals and the normalized second dark-field X-ray signals for comparing the normalized first dark-field X-ray signals with the normalized second dark-field X-ray signals, and to determine whether the at least one area of the patient's lung with the ventilation defect exists, if a mathematical norm of the calculated difference exceeds or goes below a predefined threshold.
7. The calculation device according to claim 6 , wherein the predefined threshold is based on the ratio between the lung volume at inspiration and the lung volume at expiration.
8. The calculation device according to claim 7 , wherein the output signal comprises a marked area, which corresponds to the at least one area of the patient's lung with the ventilation defect.
9. The calculation device according to claim 1 , further configured to determine a value, which corresponds with the ventilation of the patient's lung based on the comparison result.
10. The calculation device according to claim 1 , further configured to determine a lung volume V e at expiration and a lung volume V i at inspiration, to determine an expected mean signal change of the normalized first dark-field X-ray signals at expiration and the normalized second dark-field X-ray signals at inspiration by using the determined lung volumes V e and V i , to determine whether the at least one area of the patient's lung with the ventilation defect exists based on the determined expected mean signal change and a comparison with the normalized first dark-field X-ray signals and the normalized second dark-field X-ray signals.
11. The calculation device according to claim 10 , wherein the expected mean signal change is derived from:
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with D e and D i as normalized dark-field X-ray signals for the expiration and inspiration state, l e and l i as lung thicknesses for the expiration and inspiration state, and V e and V i as lung volumes for the expiration and inspiration state.
12. The calculation device according to claim 1 , further configured to generate an output signal describing the comparison result to a display for graphically displaying the comparison result and determining whether the at least one area of the patient's lung with the ventilation defect exists.
13. A dark-field X-ray imaging device, comprising a calculation device according to claim 1 , wherein the dark-field X-ray imaging device is configured to generate the first dark-field X-ray image and the second dark-field X-ray image and provide the images to the calculation device.
14. A method for determining whether at least one area of a patient's lung with a ventilation defect exists by using dark-field X-ray imaging data, comprising:
providing a first dark-field X-ray image describing first dark-field X-ray signals of a patient at an expiration state;
providing a second dark-field X-ray image describing second dark-field X-ray signals of the patient at an inspiration state;
normalizing the first dark-field X-ray signals of the first dark-field X-ray image with a lung thickness value describing the lung thickness at the expiration state;
normalizing the second dark-field X-ray signals of the second dark-field X-ray image with a lung thickness value describing the lung thickness at the inspiration state;
comparing the normalized first dark-field X-ray signals with the normalized second dark-field X-ray signals and determining a comparison result; and
determining whether at least one area of the patient's lung with the ventilation defect exists based on the comparison result.
15. A non-transitory computer-readable medium for storing executable instructions, when executed by processing circuitry, cause the processing circuitry to perform a method for determining whether at least one area of a patient's lung with a ventilation defect exists by using dark-field X-ray imaging data, the method comprising:
providing a first dark-field X-ray image describing first dark-field X-ray signals of a patient at an expiration state;
providing a second dark-field X-ray image describing second dark-field X-ray signals of the patient at an inspiration state;
normalizing the first dark-field X-ray signals of the first dark-field X-ray image with a lung thickness value describing the lung thickness at the expiration state;
normalizing the second dark-field X-ray signals of the second dark-field X-ray image with a lung thickness value describing the lung thickness at the inspiration state;
comparing the normalized first dark-field X-ray signals with the normalized second dark-field X-ray signals and determining a comparison result; and
determining whether at least one area of the patient's lung with the ventilation defect exists based on the comparison result.