Ultrasound diagnostic apparatus and ultrasound three-dimensional image creation method

1. An ultrasound diagnostic apparatus to display a three-dimensional image of an object based on luminance volume data, the ultrasound diagnostic apparatus comprising:

a light source information setting unit configured to set light source data indicating a property of a light source that is set in a three-dimensional space;

an optical property setting unit configured to set a first weight coefficient indicating an optical property of the luminance volume data with respect to the light source;

an illuminance calculation unit configured to calculate an illuminance at a position corresponding to a coordinate of the luminance volume data, based on the light source data and the first weight coefficient, and to create illuminance volume data based on the calculated illuminance; and

a volume rendering unit configured to create the three-dimensional image from the luminance volume data and the illuminance volume data,

wherein the optical property setting unit sets the first weight coefficient depending on a luminance of the luminance volume data and a distance from a surface of the object.

2. The ultrasound diagnostic apparatus according to claim 1 , wherein the illuminance calculation unit comprises:

a two-dimensional convolution processing unit configured to conduct two-dimensional convolution of the light source data to generate two-dimensional convolution data; and

a first weighted addition unit configured to conduct weighted addition of the light source data and the two-dimensional convolution data based on the first weight coefficient to create the illuminance volume data.

3. The ultrasound diagnostic apparatus according to claim 2 , wherein

the illuminance calculation unit

comprises a light source data holding unit configured to hold an initial value of the light source data and a result of the weighted addition by the first weighted addition unit, as input light source data,

generates two-dimensional convolution data, by conducting two-dimensional convolution of the input light source data while switching a voxel luminance from an illuminance calculation starting position to an illuminance calculation ending position in the luminance volume data, and

creates the illuminance volume data, by conducting weighted addition of the input light source data and the two-dimensional convolution data based on the first weight coefficient.

4. The ultrasound diagnostic apparatus according to claim 1 , wherein

the volume rendering unit creates the three-dimensional image, based on an opacity to be referred to by an illuminance of the illuminance volume data and a luminance of the luminance volume data.

5. The ultrasound diagnostic apparatus according to claim 1 , wherein

the first weight coefficient is specified by a two-dimensional weight coefficient table whose indexes are a luminance of the luminance volume data and a distance from a surface of the object.

6. The ultrasound diagnostic apparatus according to claim 1 , wherein

the light source information setting unit sets the light source data by adjusting at least one of an intensity of the light source, a position of the light source in the three-dimensional space, a direction of the light source, a color tone of the light source, and a shape of the light source.

7. The ultrasound diagnostic apparatus according to claim 1 , wherein

the light source information setting unit sets the light source data corresponding to a plurality of wavelengths of the light source,

the optical property setting unit sets the first weight coefficient for each of the plurality of wavelengths, and

the illuminance calculation unit creates the illuminance volume data for each of the plurality of wavelengths.

8. The ultrasound diagnostic apparatus according to claim 1 , comprising:

a corrected light source information setting unit configured to set an opposite direction to a visual line direction in the three-dimensional space, as a corrected light source direction, and to set corrected light source data indicating a property of a corrected light source that emits light in the corrected light source direction;

a corrected optical property setting unit configured to set a second weight coefficient indicating an optical property of the luminance volume data with respect to the corrected light source; and

an illuminance correction unit configured to calculate an illuminance at a position corresponding to a coordinate of the luminance volume data, based on the corrected light source data and the second weight coefficient, and to create corrected illuminance volume data based on the calculated corrected illuminance, wherein

the corrected optical property setting unit sets the second weight coefficient depending on a luminance of the luminance volume data and a distance from a surface of the object, and

the volume rendering unit creates the three-dimensional image from the luminance volume data and the corrected illuminance volume data.

9. The ultrasound diagnostic apparatus according to claim 8 , wherein

the illuminance correction unit comprises:

an addition unit configured to add the corrected light source data and the illuminance volume data;

a two-dimensional convolution processing unit configured to generate two-dimensional convolution data, by conducting two-dimensional convolution of an added value of the corrected light source data and the illuminance volume data; and

a second weighted addition unit configured to create the corrected illuminance volume data, by conducting weighted addition of the corrected light source data and the two-dimensional convolution data based on the second weight coefficient.

10. The ultrasound diagnostic apparatus according to claim 1 , comprising

a display unit configured to display a color map whose indexes are a luminance of the luminance volume data and a distance from a surface of the object, the color map corresponding to a two-dimensional weight coefficient table that specifies the first weight coefficient.

11. The ultrasound diagnostic apparatus according to claim 10 , wherein

the display unit selectively displays a plurality of the color maps corresponding to a plurality of two-dimensional weight coefficient tables each of which specifies the first weight coefficient corresponding to a tissue of the object.

12. The ultrasound diagnostic apparatus according to claim 2 , wherein

the two-dimensional convolution processing unit generates a plurality of two-dimensional convolution data, by conducting a plurality of two-dimensional convolution for the light source data.

13. An ultrasound three-dimensional image creation method of displaying a three-dimensional image of an object based on luminance volume data, the ultrasound three-dimensional image creation method comprising:

setting light source data indicating a property of a light source that is set in a three-dimensional space;

setting a weight coefficient indicating an optical property of the luminance volume data with respect to the light source, depending on a luminance of the luminance volume data and a distance from a surface of the object;

calculating an illuminance at a position corresponding to a coordinate of the luminance volume data, based on the optical data and the weight coefficient, and creating illuminance volume data based on the calculated illuminance; and

creating the three-dimensional image from the luminance volume data and the illuminance volume data.