Medical image processing apparatus, x-ray diagnostic apparatus, phantom, and medical image processing method

1. A medical image processing apparatus comprising:

a computer configured to:

obtain X-ray image data of an object including not less than three phantoms whose X-ray absorption factors are different from each other and whose forms are spherical, the phantoms simulating different concentrations of a contrast agent, the phantoms being used for a calibration of pixel values; and

generate corrected X-ray image data of the object by correcting the obtained X-ray image data, the obtained X-ray image data being corrected using a nonlinear function obtained based on pixel values of the obtained X-ray image data, the pixel values of the obtained X-ray image data corresponding to the phantoms,

wherein said computer is configured to obtain a nonlinear function whose influence of an error in at least one of the X-ray absorption factors of the phantoms has been corrected, based on information indicating a relation between previously obtained concentrations of a contrast agent and pixel values of X-ray image data.

2. A medical image processing apparatus of claim 1 ,

wherein said computer is configured to:

obtain first X-ray image data of the object including the phantoms and second X-ray image data of the object without the phantoms; and

generate the corrected X-ray image data of the object by correcting the second X-ray image data using the nonlinear function.

3. A medical image processing apparatus of claim 1 ,

wherein said computer is configured to obtain the nonlinear function based on pixel values corresponding to X-ray absorption factors distributing at unequal intervals.

4. A medical image processing apparatus of claim 1 ,

wherein said computer is configured to obtain a cubic equation, a quartic equation or a quintic equation as the nonlinear function.

5. A medical image processing apparatus of claim 1 ,

wherein said computer is configured to obtain nonlinear functions corresponding to regions different from each other and correct the different regions respectively using the nonlinear functions, the nonlinear functions being obtained based on frames of X-ray image data obtained in states where a phantom set consisting of the phantoms has been arranged in the different regions.

6. A medical image processing apparatus of claim 1 ,

wherein said computer is configured to obtain nonlinear functions corresponding to regions different from each other and correct the different regions respectively using the nonlinear functions, the nonlinear functions being obtained based on one frame of X-ray image data obtained in a state where a phantom set consisting of the phantoms has been arranged in each of the different regions.

7. A medical image processing apparatus of claim 2 ,

wherein said computer is configured to obtain the second X-ray image data at a same imaging position as an imaging position of the first X-ray image data.

8. An X-ray diagnostic apparatus comprising:

an X-ray tube and an X-ray detector configured to acquire X-ray image data of an object including not less than three phantoms whose X-ray absorption factors are different from each other and whose forms are spherical, the phantoms simulating different concentrations of a contrast agent, the phantoms being used for a calibration of pixel values; and

a computer configured to generate corrected X-ray image data of the object by correcting the acquired X-ray image data, the acquired X-ray image data being corrected using a nonlinear function obtained based on pixel values of the acquired X-ray image data, the pixel values of the acquired X-ray image data corresponding to the phantoms,

wherein said computer is configured to obtain a nonlinear function whose influence of an error in at least one of the X-ray absorption factors of the phantoms has been corrected, based on information indicating a relation between previously obtained concentrations of a contrast agent and pixel values of X-ray image data.

9. A medical image processing method comprising:

obtaining X-ray image data of an object including not less than three phantoms whose X-ray absorption factors are different from each other and whose forms are spherical, the phantoms simulating different concentrations of a contrast agent, the phantoms being used for a calibration of pixel values;

generating corrected X-ray image data of the object by correcting the obtained X-ray image data, the obtained X-ray image data being corrected using a nonlinear function obtained based on pixel values of the obtained X-ray image data, the pixel values of the obtained X-ray image data corresponding to the phantoms; and

obtaining a nonlinear function whose influence of an error in at least one of the X-ray absorption factors of the phantoms has been corrected, based on information indicating a relation between previously obtained concentrations of a contrast agent and pixel values of X-ray image data.

10. A medical image processing apparatus of claim 1 ,

wherein said computer is configured to obtain the nonlinear function based on pixel values corresponding to center portions of the phantoms.

11. A medical image processing apparatus of claim 10 ,

wherein the phantoms are automatically recognized by pattern matching, and

pixel values at center portions of the recognized phantoms are measured.

12. A medical image processing apparatus of claim 10 ,

wherein the pixel values corresponding to the center portions of the phantoms are obtained by measuring a maximum value of pixel values corresponding to each of the phantoms.