X-ray CT device

1. An X-ray CT device that generates a CT image of an object, comprising:

an X-ray tube;

an X-ray detector that detects an X-ray image irradiated from the X-ray tube;

a rotating plate that rotates the X-ray tube and the X-ray detector around an axis of rotation; and

a DAS (Data Acquisition System) chip that reads out a signal detected by the X-ray detector at a predetermined image scanning timing and a signal processor that processes a signal that has been output from the DAS chip to generate the CT image of the object,

wherein the DAS chip adds and outputs signals detected by Nx detection pixels that are adjacent in an X direction and/or Nz detection pixels that are adjacent in a z direction in a plurality of detection pixels configured in a matrix on an X-ray input plane of the X-ray detector, and performs changing of an addition position of the detection pixel where an addition is performed in synchronization with the image scanning timing, wherein the X-ray detector is provided with a plurality of small regions that have been set in advance in a detection region and arranged in an X direction,

wherein values of the Nx and Nz can be individually set for the plurality of small regions in accordance with a purpose of imaging scanning,

wherein the Nx and Nz are integers of 1 or more and either one of the Nx and Nz is 2 or more,

wherein the signal processor performs a correction operation for reducing a reduction in spatial resolution caused by crosstalk, by using an amount of the crosstalk between an added pixel concerned and an added pixel that is adjacent to the added pixel concerned for all added pixels that are formed in a frame cycle of changing of the addition position, wherein a large pixel unit formed by adding the detection pixels is referred to as the added pixel,

wherein the signal processor performs a back projection operation to produce interpolation data by executing interpolation using data obtained in a plurality of different adding positions to reduce a sampling interval and to improve a Nyquist frequency, the produced interpolation data including a smaller sampling interval than adding position, and

wherein the signal processor generates the CT image, by using calibration data needed when generating the CT image for all added pixels formed in a frame cycle of changing of the addition position.

2. The X-ray CT device according to claim 1 , wherein the DAS chip cyclically changes the addition position of the detection pixel where the addition is performed.

3. The X-ray CT device according to claim 1 , further comprising:

a setting screen that designates the Nx and Nz.

4. The X-ray CT device according to claim 1 , further comprising:

a display that is to be connected to the signal processor,

wherein the setting screen is configured by a display screen of the display.

5. The X-ray CT device according to claim 1 , wherein the plurality of small regions are a detector central area, and two detector peripheral areas interposing the detector central area.

6. The X-ray CT device according to claim 1 , wherein the DAS chip includes a pixel addition circuit that adds an output signal from the X-ray detector, a signal detected by the detection pixels, a sample hold circuit that samples the signal detected by the detection pixel at a predetermined timing, and an ADC circuit that converts the signal detected by the detection pixel into a digital signal.

7. The X-ray CT device according to claim 6 , wherein the image scanning timing is the predetermined timing of the sample hold circuit.

8. The X-ray CT device according to claim 7 , wherein the pixel addition circuit is disposed at a front stage of the sample hold circuit, at a rear stage of the sample hold circuit, or at a rear stage of the ADC circuit.

9. The X-ray CT device according to claim 1 , wherein the DAS chip sets minimum units of position change amounts in the x direction and the z direction in which the addition position is changed respectively as Mx and Mz, wherein, Mx is an integer of 0≦Mx<Nx, and Mz is an integer of 0≦Mz<Nz,

sets either one of the Mx and Mz to 2 or more, or

value(s) of the Mx and/or Mz can be designated from within 2 or more kinds of different choices.

10. The X-ray CT device according to claim 9 ,

wherein the X-ray detector is configured by arraying a plurality of small X-ray detectors, Kx is a number of the detection pixels in the x direction, and Lx is a maximum value of a number of signals outputted in the X direction,

wherein the DAS chip parallel-processes Lx ones to allocate in the respective x directions of the small X-ray detectors by one of:

in a case that Nx is 2 or more and Mx is 1 or more, Kx=Nx×Jx+Ix, Ix is an integer that meets 0≦Ix<Nx, Lx=Jx+1 in a case where Ix=0, or Ix=1, or Ix=Mx and Nx is a multiple of Mx, or

in a case other than the above Lx=Jx+2.

11. The X-ray CT device according to claim 9 ,

wherein the X-ray detector is configured by arraying a plurality of small X-ray detectors, Kz is a number of the detection pixels in the z direction, and Lz is a maximum value of a number of signals outputted in the z direction,

wherein the DAS chip parallel-processes Lz ones to allocate in the respective z directions of the small X-ray detectors by one of:

in a case that Nz is 2 or more and Mz is 1 or more, Kz=Nz×Jz+Iz, Iz is an integer that meets 0≦Iz<Nz, Lz=Jz+1 in a case where Iz=0, or Iz=1, or Iz=Mz and Nz is a multiple of Mz, or

in a case other than the above, Lz=Jz+2.

12. The X-ray CT device according to claim 1 , further comprising:

a memory that stores the crosstalk amount that has been calculated in advance.

13. The X-ray CT device according to claim 1 , further comprising: a memory that stores the calibration data that has been calculated in advance.