JP4640589B2 - X-ray equipment - Google Patents

Description

Relates the X-ray imaging apparatus of the present invention for industrial, in particular, to referred X-ray imaging apparatus with a so-called X-ray CT apparatus or the like for obtaining a tomographic image of the Utsushitai.

As a method for observing various industrial products and the like under non-destructive methods, a method using an X-ray imaging apparatus such as an X-ray fluoroscope or an X-ray CT apparatus has been conventionally known. In the X-ray fluoroscopic apparatus, as schematically shown in FIG. 5 , an X-ray source 71 and an X-ray detector 72 are arranged to face each other, and a holding unit 73 such as a table for holding the subject W is provided therebetween. The arrangement | positioning structure is taken (for example, refer patent document 1). In the X-ray CT apparatus, as schematically shown in FIG. 6 , the X-ray source 81 and the X-ray detector 82 are similarly arranged opposite to each other, and the subject W is held therebetween, and the X-ray optical axis L A configuration is adopted in which a rotary table 83 for giving rotation about a rotation axis R perpendicular to the axis is arranged (see, for example, Patent Document 2).

  In these apparatuses, X-rays generated from an X-ray source are transmitted through a subject W and then incident on an X-ray detector, and X-ray transmission data that is an output of each pixel of the X-ray detector, that is, each pixel's output. Import grayscale information. In the X-ray fluoroscopic apparatus, the density information of each pixel of the X-ray detector 72 is made to correspond to the position of each pixel, and the density of the display pixel of the display is determined and displayed on the display, so that the X-ray of the subject is displayed. Construct a perspective image.

  On the other hand, in the X-ray CT apparatus, by rotating the rotation table 83, the subject W is rotated about the rotation axis R, and X-ray transmission data from the X-ray detector 82 is taken in every minute rotation angle. Usually, a tomographic image in which a subject is sliced on a plane orthogonal to the rotation axis R is constructed by reconstructing X-ray transmission data for 360 °.

The imaging magnification in these apparatuses, that is, the enlargement ratio, is determined by the ratio of the distance (SOD) between the X-ray source (focus) and the subject W and the distance (SID) between the X-ray source (focus) and the X-ray detector. . In these apparatuses, the holding unit 73 or the rotary table 83 is usually moved in the direction along the X-ray optical axis L, or the X-ray detectors 72 or 82 so that such an imaging magnification can be freely selected. Are moved in the same direction, and further a drive mechanism for moving the X-ray source 71 or 81 in the same direction is provided. In addition, in the X-ray fluoroscopic apparatus, by providing a moving mechanism that moves the holding unit 73 on a plane orthogonal to the X-ray optical axis L, the observation target portion (attention site) of the subject W is centered on the fluoroscopic image. Ru Tei can now be located. In the X-ray CT apparatus, a moving table that holds or mounts the subject W and moves along a plane orthogonal to the X-ray optical axis L is disposed on the rotary table 83, and the moving table is driven. By moving the subject W with respect to the rotation axis R in many cases, it is often configured to obtain a tomographic image centered on the region of interest of the subject W.
JP 2004-170226 A JP 2004-184122 A

By the way, there are various types of X-ray detectors, all of which have a fixed visual field and the number of pixels, and the output finally becomes digital data which is the density value of each pixel. This field of view and the number of pixels are uniquely determined by the X-ray detector used, and a high-resolution X-ray fluoroscopic image or X-ray tomographic image can be obtained by using a detector with a large number of pixels in a fixed field of view. However, there is a problem that the cost increases. In addition, if the detectors have the same size, it is inevitable that the sensitivity decreases due to an increase in the number of pixels.

An object of the present invention is to provide an X-ray imaging apparatus capable of obtaining a high-resolution X- ray tomographic image with almost no increase in cost and without reducing sensitivity.

In order to solve the above-described problems, in the X-ray imaging apparatus of the present invention, a holding unit that holds a subject is disposed between an X-ray source and an X-ray detector that are arranged to face each other, and the holding unit. A rotation driving means for rotating the subject held by the X-ray source around a rotation axis perpendicular to the X-ray optical axis, and the subject held by the holding portion while irradiating the subject with X-rays An image forming means for reconstructing X-ray transmission data obtained by an imaging operation for capturing the output of the X-ray detector for each minute rotation angle and constructing a tomographic image of a subject orthogonal to the rotation axis In the X-ray imaging apparatus provided,
A holding unit moving mechanism capable of moving the holding unit on a plane orthogonal to the X-ray optical axis from the X-ray source at an integer pitch of the pixel pitch of the X-ray detector; the X-ray imaging means, the X-ray transmission data taken each at a plurality of positions shifting the holding portion by its holding portion moving mechanism in one pitch of the integral fraction, X-rays obtained by one shooting operation Characterized by constructing a tomographic image of a subject treated as transmission data.

  In the present invention, the object holding unit is placed on the X-ray source and the X-ray detector at a pitch that is an integral number of the pixel pitch of the X-ray detector on a plane orthogonal to the X-ray optical axis from the X-ray source. The present invention intends to solve the problem by handling X-ray transmission data captured at a plurality of positions shifted relative to each other as X-ray transmission data obtained by one imaging operation.

That is, the object holding unit is set in two directions orthogonal to the X-ray source and the X-ray detector on a plane orthogonal to the X-ray optical axis at a pitch of 1/2 of the pixel pitch of the X-ray detector, for example. When X-ray transmission data captured at a total of four positions are handled as X-ray transmission data obtained by one imaging and X- ray tomograms are constructed, the spatial resolution of these images is originally determined by the X-ray detector. The spatial resolution is four times higher than that of the spatial resolution, and the sensitivity is the same as that inherent in the X-ray detector.

According to the present invention, same with the X-ray detector, as compared with the conventional X-ray imaging apparatus can obtain a higher have X-ray tomographic image resolution, moreover, no reduction in sensitivity, further The holder moving mechanism that many X-ray imaging apparatuses have for moving the perspective field of view can be used as it is. Thus, high-resolution X-ray fluoroscopic equipment is obtained at low cost.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an embodiment of the present invention , and is a diagram showing a schematic diagram showing a mechanical configuration and a block diagram showing a system configuration . FIG. 2 is a schematic plan view of the mechanical configuration. Indicates.

X-ray source generator 2 1 outputs a cone-shaped X-ray from the focal point 2 1a. Opposed to the X-ray detector having a two-dimensional detection plane 2 2 is disposed in the X-ray generator 2 1. The X-ray detector 2 2 is FPD. Between these X-ray generator 2 1 and the X-ray detector 2 2, the turntable 2 3 are arranged as a rotary drive means for imparting rotation to the object holder and object W to hold the object W .

The rotation axis R of the turntable 23 is along the z-axis direction orthogonal to the X-ray optical axis L (x-axis direction) from the X-ray generator 21. The rotary table 23 can be moved by the table moving mechanism 24 in the x-axis direction that is the X-ray optical axis direction and in the y and z-axis directions orthogonal to the x-axis.

On the rotary table 23, y orthogonal mounted hold the object W in X-ray optical axis L, the subject fine movement mechanism 25 for finely moving in the z-axis direction is disposed. The subject fine movement mechanism 25 can finely move the subject W in the y-axis direction and the z-axis direction at a pitch that is an integral number of the pixel pitch a of the X-ray detector 22, for example, 1/2.

  The rotary table 23 is rotated by a drive signal from the rotary table drive circuit 31, and the table moving mechanism 24 and the subject fine movement mechanism 25 are driven and controlled by signals from the table movement mechanism drive circuit 32 and the subject fine movement mechanism drive circuit 33, respectively. Is done. The rotary table drive circuit 31, the table moving mechanism drive circuit 32, and the subject fine movement mechanism drive circuit 33 are placed under the control of the personal computer 34. The personal computer 34 is connected with a tomogram reconstruction calculation device 35 and is also connected with an operation unit 36 such as a mouse, a keyboard, or a joystick, and a display 37 for displaying a tomogram or the like. .

  At the time of CT imaging, the subject W is rotated around the rotation axis R by a minute angle while irradiating the subject W placed on the subject fine movement mechanism 25 on the rotary table 23 with each rotation. X-ray transmission data, which is each pixel output of the X-ray detector 2, is taken into the tomographic image reconstruction calculation device 35 for each angle. In this tomographic image reconstruction calculation device 35, the acquired X-ray transmission data is reconstructed as will be described later, whereby a slice plane set through the operation unit 36 (xy plane at an arbitrary position in the z-axis direction). A tomographic image of the subject W along the line is constructed and displayed on the display 37.

  Prior to CT imaging, the table moving mechanism 34 is moved by operating the operation unit 36 to set the imaging magnification by setting the SOD, or to move the attention area of the subject W to the center of the visual field, and the like. The normal mode and the high resolution mode can be selected as the CT imaging mode by the operation of 36.

  When the normal mode is selected, the tomogram reconstruction calculation device 35 rotates the subject W over 360 ° while irradiating X-rays as described above, as in the conventional X-ray CT device. For each rotation angle, each pixel output from the X-ray detector 2 is captured and stored, and a tomographic image of the subject W is constructed by reconstruction calculation using them.

On the other hand, when the high resolution mode is selected, CT imaging is performed according to the following procedure. That is, assuming that the pixel pitch of the X-ray detector 22 is a in the x and y axis directions as shown in FIG. 3A, first, the tomographic image reconstruction calculation device 35 has an initial position (initial position). ) in store captures X-ray transmission data from the same manner as described above each pixel of the X-ray detector 2 2 P (1 st CT imaging), then, under the control signal supplied from the personal computer 34 Then, the subject fine movement mechanism 25 is driven to automatically move the subject W in the y-axis direction by ½ of the pixel pitch a of the X-ray detector 2, and similarly from each pixel of the X-ray detector 2. X-ray transmission data is captured and stored (second CT imaging), and the subject W is automatically moved by a / 2 in the z-axis direction by driving the subject fine movement mechanism 25, and then the X-rays from each pixel are captured. Capture and store the line transmission data (3rd CT scan In addition, the subject W is automatically moved by a / 2 in the direction opposite to the above in the y-axis direction by driving the subject fine movement mechanism 25, and then X-ray transmission data from each pixel is taken in and stored. (4th CT scan).

3 (B) is more than a diagram showing the spatial distribution of X-ray transmission data obtained by the photographing operation, the X-ray transmission data obtained by the photographing of 1-4 th schematically represented by T1~T4 Show. As shown in this figure, the total spatial resolution of X-ray transmission data obtained by a total of four imagings is equivalent to the spatial resolution of data obtained by an X-ray detector with a pixel pitch of a / 2.

In the cross-sectional layer image reconstruction calculation unit 35, handling all the X-ray transmission data obtained by the total of four CT imaging as an integral, i.e. as a substantially X-ray transmission data obtained by one of CT imaging Handling and reconstructing a tomographic image of the subject W. Therefore, the obtained tomographic image is obtained by a conventional X-ray CT apparatus using an X-ray detector having the same spatial resolution as that of the X-ray detector 22, in other words, a tomographic image obtained by CT imaging in the normal mode. Spatial resolution is improved by a factor of 4 compared to the tomographic image.

When the subject W is finely moved as described above, as shown schematically in FIG. 4 , data obtained by seeing through the same position Wp of the subject W from different directions can be obtained by photographing before and after the fine movement. Although some distortion will occur in the front and back images, if the position (coordinates) of the subject W is known in advance, this distortion can be corrected by calculation using a known method, and there is a z-axis direction. An image without distortion can be created in the xy plane passing through the coordinates. Further, when the X-ray irradiation angle is narrow, this distortion can be ignored.

  In each of the above-described examples, the FPD is used as the X-ray detector, but an X-ray detector combining an image intensifier and a CCD may be used.

In block diagram of the implementation of the embodiment of the present invention, it is a view showing shown together with a block diagram showing the schematic system configuration representing the mechanical structure. FIG. 2 is a schematic plan view of a mechanical configuration in FIG. 1 . In illustration of X-ray transmission data obtained by the photographing operation according to an embodiment of the present invention, (A) is an explanatory view of the arrangement example of the pixel X-ray detector 2, (B) fine movement of an object fine movement mechanism It is explanatory drawing of the spatial distribution of the X-ray-transmission data obtained by letting it image | photograph 4 times. In the present invention, it is an explanatory view of the position of the X-ray detector X-rays transmitted through the same position Wp of the object W by the imaging before and after the fine movement of the object scene object is incident. It is a schematic diagram which shows the example of a fundamental structure of the conventional X-ray fluoroscope. It is a schematic diagram which shows the example of a fundamental structure of the conventional X-ray CT apparatus.

21 X-ray generator 21a Focus (X-ray source)
22 X-ray detector 23 Rotary table 24 Table moving mechanism 25 Subject fine movement mechanism 31 Rotary table drive circuit 32 Table movement mechanism drive circuit 33 Subject fine movement mechanism drive circuit 34 Personal computer 35 Tomographic image reconstruction calculation device 36 Operation unit 37 Display unit L X-ray optical axis R Rotation axis W Subject

Claims (1)

Between the X-ray source and the X-ray detector arranged opposite to each other, a holding unit that holds the subject is arranged, and the subject held by the holding unit is placed on the X-ray optical axis from the X-ray source. Rotation driving means for giving rotation about an orthogonal rotation axis, and rotating the subject while irradiating the subject held by the holding portion with X-rays, and outputting the X-ray detector for each minute rotation angle In an X-ray imaging apparatus provided with image forming means for reconstructing X-ray transmission data obtained by an imaging operation for capturing image and constructing a tomographic image of a subject orthogonal to the rotation axis ,
A holding unit moving mechanism capable of moving the holding unit on a plane orthogonal to the X-ray optical axis from the X-ray source at an integer pitch of the pixel pitch of the X-ray detector; the X-ray imaging means, the X-ray transmission data taken each at a plurality of positions shifting the holding portion by its holding portion moving mechanism in one pitch of the integral fraction, X-rays obtained by one shooting operation An X-ray imaging apparatus characterized by constructing a tomographic image of a subject by handling as transmission data.

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