Measurement X-ray CT apparatus
A measurement X-ray CT apparatus calibrates a geometrical positional relationship between a focus of an X-ray source, an X-ray detector, and a rotation center of a rotating table in advance. The measurement X-ray CT apparatus then obtains projection images by irradiating the object to be measured with X-rays to perform a CT scan, and generates a three-dimensional image of the object to be measured by CT reconstruction of the projection images. The measurement X-ray CT apparatus further includes a reference frame that is made of a material and has a structure less susceptible to environmental changes, and sensors that are located on the reference frame and intended to successively obtain calibration values of the geometrical positional relationship between the focus of the X-ray source and the X-ray detector during the CT scan. The calibration values are used as parameters of the CT reconstruction.
1. A measurement X-ray CT apparatus comprising:
a rotating table configured to rotate about an axis and to accept an object to be measured to be placed thereon, and a scanning mechanism configured to move the rotating table to a given position in a measurement space region, the rotating table and the scanning mechanism being located between an X-ray source and an X-ray detector,
the measurement X-ray CT apparatus being configured to calibrate a geometrical positional relationship between a focus of the X-ray source, the X-ray detector, and a rotation center of the rotating table in advance, obtain projection images by irradiating the object to be measured with X-rays to perform a CT scan, and generate a three-dimensional image of the object to be measured by CT reconstruction of the projection images,
the measurement X-ray CT apparatus further comprising:
a reference frame that is made of a material and has a structure less susceptible to an environmental change; and
a sensor that is located on the reference frame and intended to successively obtain calibration values of the geometrical positional relationship between the focus of the X-ray source and the X-ray detector during the CT scan,
wherein the calibration values are used as parameters of the CT reconstruction.
2. The measurement X-ray CT apparatus according to claim 1 , wherein the reference frame is disposed at positions of the X-ray source and the X-ray detector with the rotating table interposed therebetween.
3. The measurement X-ray CT apparatus according to claim 2 , wherein the reference frame is a metrology frame of rectangular solid shape.
4. The measurement X-ray CT apparatus according to claim 1 , wherein the reference frame is disposed at positions of the rotating table and the X-ray source, and a marker disposed on the X-ray detector is detected by a camera disposed on the reference frame.
5. The measurement X-ray CT apparatus according to claim 4 , wherein the reference frame is a metrology frame of cubic shape.
6. The measurement X-ray CT apparatus according to claim 5 , wherein the marker is a light-emitting diode.
7. The measurement X-ray CT apparatus according to claim 1 , wherein the reference frame is disposed at a position of the X-ray source, and a corner cube disposed on the X-ray detector is detected by a laser interferometer disposed on the reference frame.
8. The measurement X-ray CT apparatus according to claim 1 , further comprising:
an eccentricity measuring device disposed on the rotating table; and
a sensor configured to detect a position of the eccentricity measuring device, the sensor being disposed on the reference frame.
9. The measurement X-ray CT apparatus according to claim 8 , wherein a reference surface for eccentricity measurement is formed on an outer periphery of the rotating table.
10. The measurement X-ray CT apparatus according to claim 1 , further comprising a sensor configured to detect a position of the rotating table, the sensor being located on the reference frame.
11. The measurement X-ray CT apparatus according to claim 10 , wherein the sensor is a laser tracker configured to detect a cat eye reflector disposed on a measurement object fixing jig on the rotating table.