X-ray radiographic apparatus - Patent Review 5539798

What we claim is:

1. An X-ray radiographic apparatus for radiographing an X-ray image of an object, comprising:

an X-ray tube having an X-ray focal point for radiating X-ray beams toward the object;

an X-ray beam limiting device incorporating a limiting member making an adjustable aperture in size limiting the X-ray beams passing therethrough, the limiting member being positioned between the X-ray tube and the object;

means for obtaining a surface image of the object viewing through the aperture, the surface image obtaining means having an optical mirror passing the X-ray beams and being arranged between the X-ray tube and the limiting member on the way of an X-ray beam path formed by the X-ray beams, and an optical imaging element producing the surface image responsively to light rays received through the aperture by optical reflection at the mirror;

means for forming a frame image representing a target size of the aperture in accordance with a given size information; and

means for displaying the surface image on which the frame image is superposed.

2. An X-ray radiographic aperture according to claim 1, further comprising:

a specifying means for specifying a desired size of the frame image by giving the size information to the frame image forming means.

3. An X-ray radiographic apparatus according to claim 2, further comprising:

means for driving the limiting member so as to control an actual size of the aperture into a predetermined full open until the target size of the aperture is determined.

4. An X-ray radiographic apparatus according to claim 3, further comprising:

another means for driving the limiting member so as to control the actual size of the aperture into the desired size of the frame image specified by being determinedly displayed on the surface image displaying means after the target size of the aperture is determined.

5. An X-ray radiographic apparatus according to claim 1, wherein the optical imaging element is an optical camera means for photographing the surface image, the camera means being incorporated in the X-ray beam limiting device.

6. An X-ray radiographic apparatus according to claim 5, wherein the optical mirror is disposed so as to reflect the light rays received through the aperture from the object into a side direction to the X-ray beam path and make the light rays converge at an optically conjugate position to a position of the X-ray focal point, the optically conjugate position lying within the X-ray beam limiting device.

7. An X-ray radiographic apparatus according to claim 6, wherein the camera means is disposed at the optically conjugate position.

8. An X-ray radiographic apparatus according to claim 7, wherein the camera means is an infrared TV camera.

9. An X-ray radiographic apparatus according to claim 4, wherein the X-ray focal point is one in number.

10. An X-ray radiographic apparatus according to claim 4, wherein the surface image displaying means comprises a monitor having a screen for displaying the surface image superposed by the frame image and the frame image specifying means has a touch panel attached on a front surface of the screen of the monitor, the touch panel being used by hand for producing the size information in accordance with a given specification mode of the size information.

11. An X-ray radiographic apparatus according to claim 10, further comprising a selecting means for selecting by hand one of a plurality of specification modes prepared as the specification mode.

12. An X-ray radiographic apparatus according to claim 11, wherein the frame image is a square frame image and the specification modes include a first mode specifying separately positions of four segments of the square frame image, a second mode specifying positions of two adjacent segment of the square frame image, and a third mode specifying a position of one corner point of the square frame image.

13. An X-ray radiographic apparatus according to claim 7, wherein the camera means is a TV camera.

14. An X-ray radiographic apparatus for radiographing an X-ray image of an object, comprising:

an X-ray tube having two X-ray focal points for each radiating X-ray beams toward the object;

an X-ray beam limiting device incorporating two limiting members each making an adjustable aperture in size for limiting the X-ray beams passing therethrough, each of the two limiting members being positioned between the X-ray tube and the object;

means for obtaining two surface images of the object viewing through each of the two apertures, the surface image obtaining means having two optical mirrors passing the X-ray beams and each being arranged between the X-ray tube and each of the two limiting members on the way of an X-ray beam path formed by each of the two X-ray beams, and an optical imaging element producing the two surface images responsively to light rays of the object received through each of the two apertures by optical reflection at each of the two mirrors; and

means for displaying the surface images.

15. An X-ray radiographic apparatus according to claim 13, wherein the optical imaging element consists of two optical camera means for each photographing the surface image, the camera means being incorporated in the X-ray beam limiting device.

16. An X-ray radiographic apparatus according to claim 15, wherein each of the two optical mirrors is disposed so as to reflect the light rays received through the aperture from the object into a side direction to the X-ray beam path and make the light rays converge at an optically conjugate position to a position of the X-ray focal point, the optically conjugate position lying within the X-ray beam limiting device.

17. An X-ray radiographic apparatus according to claim 16, wherein the two camera means are each disposed at the two optically conjugate positions.

18. An X-ray radiographic apparatus according to claim 17, wherein the surface image displaying means comprises two monitors for each displaying the surface images obtained by each of the two camera means.

19. An X-ray radiographic apparatus according to claim 17, wherein the surface image displaying means comprises one monitor for displaying the two surface images obtained by the two camera means and a switch means for selectively exchanging signals of the two surface images supplied from the two camera means to the one monitor.

20. An X-ray radiographic apparatus according to claim 14, wherein the optical imaging element consists of one optical camera means for photographing the two surface images, the camera means being incorporated in the X-ray beam limiting device and being an optical camera disposed at an optically conjugate position to positions of the two X-ray focal points, and the apparatus further comprises means for selectively exchanging to the optical camera two optical paths traveling from the object to the optical camera through the two apertures.

21. An X-ray radiographic apparatus according to claim 20, wherein the optical path exchanging means comprises two optical systems for guiding the reflected light-rays from the object to the camera along the two optical paths, two shutter means for optically opening and closing the two optical paths, and a control means for selectively driving the two shutter means into states of opening and closing of the two shutter means.

22. An X-ray radiographic apparatus according to claim 21, wherein each of the two shutter means is a shutter formed by a liquid crystal.

23. An X-ray radiographic apparatus according to claim 22, wherein the surface image displaying means has one monitor alternately displaying the two surface images.

24. An X-ray radiographic apparatus according to claim 22, wherein the surface image displaying means has one monitor for displaying the two surface images and the apparatus further comprises means for supplying R(right) and L(left) images, corresponding to the two X-ray focal points, to the monitor.

25. An X-ray radiographic apparatus according to claim 24, wherein the image supplying means includes a memory means for storing data of the R- and L-images, the memory means having a memory of a double buffer structure.

26. An X-ray radiographic apparatus according to claim 22, wherein the surface image displaying means has two monitors for displaying the two surface images and the apparatus further comprises means for distributing R(right) and L(left)images corresponding to the two X-ray focal points, to the two monitors.

27. An X-ray radiographic apparatus according to claim 26, wherein the image distributing means includes a memory means for storing data of the R- and L-images, the memory means having a memory of a double buffer structure.

28. An X-ray radiographic apparatus comprising:

an X-ray tube having an X-ray focal point for radiating X-ray beams toward an object being examined;

an X-ray beam limiting device incorporating a limiting member making an aperture for limiting the X-ray beams passing therethrough, the limiting member being positioned between the X-ray tube and the object;

means for radiographing an X-ray image based on the X-ray beams transmitted through the object;

means for obtaining a surface image of the object viewing through the aperture, the surface image obtaining means having an optical mirror passing the X-ray beams and being arranged between the X-ray tube and the limiting member on the way of an X-ray beam path formed by the X-ray beams, and an optical imaging element producing the surface image responsively to light rays received through the aperture by optical reflection at the mirror;

means for obtaining a reference image of the object for positioning to the object, the reference image being made from image data of the same object acquired in the past; and

means for combinedly displaying the surface image currently obtained and the reference image obtained in the past.

29. An X-ray radiographic apparatus according to claim 28, wherein the optical imaging element is an optical camera means for photographing the surface image, the camera means being incorporated in the X-ray beam limiting device.

30. An X-ray radiographic apparatus according to claim 29, wherein the optical mirror is disposed so as to reflect the light rays received through the aperture from the object into a side direction to the X-ray beam path and make the light rays converge at an optically conjugate position to a position of the X-ray focal point, the optically conjugate position lying within the X-ray beam limiting device.

31. An X-ray radiographic apparatus according to claim 30, wherein the camera means is disposed at the optically conjugate position.

32. An X-ray radiographic apparatus according to claim 28, wherein the camera means is a TV camera.

33. An X-ray radiographic apparatus according to claim 28, wherein the reference image obtaining means includes at least one of two memory means each storing x-ray image data acquired in the past by the X-ray image radiographing means and storing surface image data acquired in the past by the surface image obtaining means, and means for forming the reference image on the basis of at least one of the past X-ray radiographic image data and the past surface image data.

34. An X-ray radiographic apparatus according to claim 28, wherein the displaying means is a means that displays a divided image of the past reference image and the current surface image.

35. An X-ray radiographic apparatus according to claim 28, further comprising means for extracting data of a marker image from data of the surface image obtained by the surface image obtaining means on condition that a marker means transmitting the X-ray beams therethrough is set on a diagnostic portion of the object, thereby the data of surface image containing data of the mark image, and means for forming the reference image by superposing the data of the marker image on the data of the X-ray image.

36. An X-ray radiographic apparatus according to claim 35, wherein the marker means is a color tape.

37. An X-ray radiographic apparatus according to claim 28, further comprising:

means for detecting a rotation angle of the X-ray tube when the X-ray tube is rotated for radiography;

means for calculating a correction angle to make a direction of the reference image coincide with a direction of the surface image obtained from the surface image obtaining means; and

means for rotating the reference image on the basis the calculated correction angle.

38. An X-ray radiographic apparatus according to claim 37, wherein the X-ray tube is rotatable in a plane containing three ways in regard to a fixed point of the X-ray tube, the three ways being a downward position and right- and leftward side positions.

39. An X-ray radiographic apparatus according to claim 33, wherein the X-ray image radiographic means has an image intensifier receiving the X-ray beams transmitted through the object.

40. An X-ray radiographic apparatus according to claim 35, further comprising means for specifying one display mode of the reference image from a plurality of display modes prepared.

41. An X-ray radiographic apparatus according to claim 40, wherein the plurality of display modes are at least two of a first display mode specifying only a past X-ray image, a second display mode specifying only the past surface image, and a third display mode specifying a superposed image of the past X-ray image and the past surface image.

42. An X-ray radiographic apparatus for radiographing an X-ray image of an object, comprising:

an X-ray tube having an X-ray focal point for radiating X-ray beams toward the object;

an X-ray beam limiting device incorporating a limiting member making an aperture for limiting the X-ray beams passing therethrough;

means having a receiving element for receiving the X-ray beams pixel by pixel transmitted through the object;

means for obtaining a surface image of the object viewing through the aperture;

means for extracting a contour image of the object from the surface image;

means for setting a light pickup area on the extracted contour image, the light pickup area being changeable in size and location in accordance with a size and location of the contour image; and

means for controlling an X-ray beam output of the X-ray tube on the basis of an amount of the X-ray beams received through the light pickup area assigned on the receiving element.

43. An X-ray radiographic apparatus according to claim 42, wherein the light pickup area setting means is a means designating a common pixel area forming the light pickup area of the contour image and a predetermined initial light pickup area image automatically set.

44. An X-ray radiographic apparatus according to claim 43, wherein the X-ray exposure controlling means is a means for controlling the X-ray beam output of the X-ray tube on the basis of an integral X-ray amount received through the light pickup area assigned on the receiving element.

45. An X-ray radiographic apparatus according to claim 42, wherein the surface image obtaining means comprises an optical camera means for photographing the surface image, the camera means being incorporated in the X-ray beam limiting device.

46. An X-ray radiographic apparatus according to claim 45, wherein an optical mirror is disposed so as to reflect the light rays received through the aperture from the object into a side direction to the X-ray beam path and make the light rays converge at an optically conjugate position to a position of the X-ray focal point, the optically conjugate position lying within the X-ray beam limiting device.

47. An X-ray radiographic apparatus according to claim 46, wherein the camera means is disposed at the optically conjugate position.

48. An X-ray radiographic apparatus according to claim 47, wherein the camera means is a TV camera.

49. An X-ray radiographic apparatus according to claim 42, wherein the limiting member is placed between the X-ray tube and the object and the surface image obtaining means has an optical mirror passing the X-ray beams and being arranged between the X-ray tube and the limiting member on the way of an X-ray beam path formed by the X-ray beams, and an optical imaging element producing the surface image responsively to light rays received through the aperture by optical reflection at the mirror.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

The present invention relates to an X-ray radiographic apparatus, in particular, to the X-ray radiographic apparatus incorporating an optical camera for obtaining a surface image of an object being imaged, the optical camera being arranged in an X-ray beam limiting device for limiting X-ray beams radiating from an X-ray tube toward the object.

In X-ray radiography, there are two radiographic methods; one is a direct radiographic method by which an X-ray image can be obtained by exposing transmitted X-rays through an object body onto an X-ray film, while the other is an indirect radiographic method by which transmitted X-rays are converted by an image intensifier (I.I.) into visible light rays received by a TV camera to obtain an X-ray image. An X-ray radiographic apparatus employing such methods has been widely used in examinations of digestive tracts and bronchial tubes using contrast medium and other examinations.

An X-ray radiographic apparatus comprises an X-ray tube radiating X-ray beams and an X-ray beam limiting device limiting the X-ray beams from the X-ray tube for avoiding excess X-ray exposure. The X-ray beam limiting device incorporates a set of limiting blades forming an aperture for X-ray beams. Thus, adjusting the size of the aperture permits an X-ray radiation field to be specified into a desired size on the object.

FIG. 1 shows a conventionally used X-ray radiographic apparatus 1 having an X-ray tube 2 and an X-ray beam limiting device 3. In the limiting device 3, a lamp 4 is disposed at a position that is conjugate to an X-ray focal point FP of the X-ray tube 2. As shown in the figure, X-ray beams radiated from the focal point FP of the X-ray tube 2 reaches a patient P lain on a tabletop 5 of a patient couch.

Lighting up the lamp 4 allows its light rays to reflect on a mirror 6 and then to radiate onto the object P, so that a light radiation field from the lamp 4 is coincident with an X-ray radiation field.

Accordingly, prior to X-ray exposure in X-ray examination, the X-ray radiation field is known to an operator by lighting up the lamp 4. Therefore, in normal conditions, the operator has used the light radiation field to adjust the aperture of a limiting member 3a incorporated in the X-ray beam limiting device 3 and to adjust relative positional relation among the X-ray tube 2, the patient P, and X-ray beam receiving devices such as an X-ray film 7 (or cassette or image intensifier).

However, when the above X-ray radiographic apparatus is used, it is required that the radiographic room be rather dark to confirm the light radiation field (i.e., X-ray radiation field) of the lamp. The darker room requires not only much operation time for the above-mentioned various adjustments but skilled operation techniques. These drawbacks are enhanced in mass screening, thereby causing a longer examination time in mass screening.

In case that the head portion of a patient is examined, dazzling light beams fall into the patient's eyes, imposing considerable endurance on the patient.

Further, when considering the longevity of the lamp, it is preferred to avoid lighting up the lamp for a longer period of time at one time. However, a shorter operation time sometimes causes an operator to be inconvenient for obtaining a highly accurate aperture of the X-ray limiting member.

Still further, fluoroscopy using a small quantity of X-ray may be carried out in the above-mentioned indirect radiography employing an image intensifier. In such a case, the aperture of an X-ray limiting device is sometimes adjusted with a fluoroscopy image. This results in an excessive X-ray exposure to a patient.

On the other hand, the above-mentioned drawbacks are also true in stereoradiography that uses an X-ray tube having a pair of X-ray focal points therein.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to provide an X-ray radiographic apparatus that is able to improve maneuverability for specifying a desired X-ray radiation field to shorten an X-ray examination time.

Further, it is another object to provide an X-ray radiographic apparatus that is favorable to mass screening in particular.

Still further, it is another object to provide an X-ray radiographic apparatus by which an operator can readily recognize the position of a portion being diagnosed in a procedure of positioning.

Still further, it is another object to provide an X-ray radiographic apparatus by which an excessive X-ray exposure is avoidable when specifying an X-ray radiation field and radiography conditions.

These and other objects can be achieved according to the present invention, in one aspect by providing an X-ray radiographic apparatus comprising an X-ray tube having an X-ray focal point for radiating X-ray beams toward an object being examined, an X-ray beam limiting device incorporating a limiting member making an aperture for limiting the X-ray beams passing therethrough, the aperture being adjustable in size, an element for obtaining a surface image of the object through the aperture, an element for forming a frame image representing the aperture in accordance with a given size information, and an element for displaying the surface image on which the frame image is superposed.

It is preferred that the X-ray radiographic apparatus further comprises a specifying element for being able to specify by hand a size of the frame image by giving the size information to the frame image forming element. It is also preferred that the X-ray radiographic apparatus further comprises an element for driving the limiting member so that the size of the aperture is brought into a size specified by the aperture displayed on the surface image displaying element.

In another aspect according to the present invention, there is also provided an X-ray radiographic apparatus comprising an X-ray tube having two X-ray focal points for each radiating X-ray beams toward an object being examined, an X-ray beam limiting device incorporating two limiting members each making apertures for limiting the X-ray beams passing therethrough, the apertures being adjustable in size, an element for obtaining surface images of the object through each of the apertures, and an element for displaying each of the surface images.

In another aspect according to the present invention, there is also provided an X-ray radiographic apparatus comprising an X-ray radiographic apparatus comprising an X-ray tube having an X-ray focal point for radiating X-ray beams toward an object being examined, an X-ray beam limiting device incorporating a limiting member making an aperture for limiting the X-ray beams passing therethrough, an element for obtaining a surface image of the object through the aperture, an element for obtaining a reference image for positioning of X-ray radiography, and an element for displaying the surface image and reference image simultaneously.

In another aspect according to the present invention, there is also provided an X-ray radiographic apparatus comprising an X-ray tube having an X-ray focal point for radiating X-ray beams toward an object being examined, an X-ray beam limiting device incorporating a limiting member making an aperture for limiting the X-ray beams passing therethrough, an element for receiving the X-ray beams transmitted through the object, an element for obtaining a surface image of the object through the aperture, an element for extracting a contour image of the object from the surface image, an element for setting a light pickup area image on the extracted contour image; and an element for controlling exposure of the X-ray tube on the basis of an amount of the received X-ray beams on the set light pickup area,

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention; in which:

FIG. 1 is a block diagram showing a prior art;

FIG. 2 is a block diagram of an X-ray radiographic apparatus according to a first embodiment of the present invention;

FIG. 3 shows an example of a monitor image of the first embodiment;

FIG. 4 is a block diagram of an X-ray radiographic apparatus according to a second embodiment of the present invention;

FIGS. 5A to 5C each shows examples of methods of specifying a limiting frame image;

FIG. 6 is an example of a limiting frame;

FIG. 7 is a block diagram of an X-ray radiographic apparatus according to a third embodiment of the present invention;

FIG. 8 exemplify monitor images in the third embodiment;

FIG. 9 is a block diagram of an X-ray radiographic apparatus according to a variation of the third embodiment of the present invention;

FIG. 10A is a front view of an X-ray radiographic apparatus according to a fourth embodiment of the present invention;

FIG. 10B is a side view of the apparatus shown in FIG. 10A;

FIG. 10C is a plan view of the apparatus shown in FIG. 10A;

FIG. 11 represents a detailed block diagram for exchanging R- and L-images;

FIG. 12 is a block diagram partly showing an X-ray radiographic apparatus of a fifth embodiment according to the present invention;

FIG. 13 is a timing chart explaining operation of the fifth embodiment;

FIG. 14 is a block diagram partly showing an X-ray radiographic apparatus of a sixth embodiment according to the present invention;

FIG. 15 is a timing chart explaining operation of the sixth embodiment;

FIG. 16 is a block diagram of an X-ray radiographic apparatus of a seventh embodiment according to the present invention;

FIGS. 17A to 17C exemplify each monitor screens showing combined images of a reference image and a positioning image;

FIG. 18 is a block diagram of an X-ray radiographic apparatus of an eighth embodiment according to the present invention;

FIGS. 19A to 19C are images explaining superposition of a mark;

FIG. 20 is an example of a monitor screen displayed in the eighth embodiment;

FIG. 21 is a block diagram of an X-ray radiographic apparatus of a ninth embodiment according to the present invention;

FIG. 22 is a pictorial explanation of rotation of an X-ray tube;

FIG. 23A exemplifies a monitor image explaining a drawback for rotation of an X-ray tube;

FIG. 23B exemplifies a monitor image obtained in the ninth embodiment;

FIG. 24 is a block diagram of an X-ray radiographic apparatus of a tenth embodiment according to the present invention;

FIG. 25 is an explanation for extracting a contour;

FIG. 26 is an explanation for specifying a light pickup area; and

FIG. 27 is an example of a light pickup area.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the present invention will now be described with reference FIGS. 2 and 3.

FIG. 2 shows a construction of an X-ray radiographic apparatus according to this embodiment. The X-ray radiographic apparatus shown therein comprises an X-ray tube 11 having a single X-ray focal point FP. The X-ray tube 11 radiates X-ray beams from its focal point FP toward a patient P as an object to be examined lain on a tabletop 12 of a patient couch (not shown). At the X-ray radiation side of the X-ray tube 11, an X-ray beam limiting device 13 is attached for limiting X-ray beams radiated from the X-ray tube 11 into a desired size of an X-ray radiation field on the surface of the patient P.

The limiting device 13 incorporates a set of lead-made blades forming a limiting member 13a. The limiting member 13a has a square aperture whose size is adjustable by a limiting member driving device 14 including driving means such as electric motors. Although not shown in the figure, the driving device 14 is partly arranged in the limiting device 13.

The X-ray tube 11 is suspended from, for example, the ceiling by a support device 15 that is constructed to be able to move the tube 11 up and down, move it horizontally and rotate it around its lateral axis, as shown by arrows in the figure. Further, in the X-ray beam limiting device 13, a mirror 16 is disposed on the way of the X-ray beam path, being able to pass radiated X-ray beams therethrough, but being able to reflect light beams thereby.

There is further provided an optical TV camera 17 at an optically conjugate position to the X-ray focal point FP within the limiting device 13. The conjugate position is the same as a position where a conventionally-used lamp has been disposed. In consequence, the TV camera 17 is able to obtain a partial surface image of the patient P through a field depending on a size of the adjustable aperture of the limiting member 13a; in other words, the size of the partial surface image obtained by the TV camera 17 exactly represents the size of an X-ray radiation field determining an X-ray radiographic region.

Below the tabletop 12, there is an X-ray film cassette 18 containing X-ray films, which will receive transmitted X-ray beams through a patient p.

The X-ray radiographic apparatus further comprises, as shown in FIG. 2, an operating device 20, a graphic data former 21, an image data composing unit 22 and a TV monitor 23 as well as an X-ray controller 24.

The operating device 20 is used by hand for adjusting the aperture size of the limiting member 13a of the limiting device 13. This operating device 20 has not only a CPU system including a memory therein but a knob 20a for use by an operator. Operating the knob 20a permits the operating device 20 to provide the graphic data former 21 a signal representing data of a desired aperture size given through the knob 20a. Further, the operating device 20 is capable of temporarily memorizing in its memory a target value of a desired aperture size finally determined by the operator.

In response to a signal representing an aperture size (i.e., the size of gradation field) from the operating device 20, the limiting member driving device 14 is able to adjust its aperture size. This driving device 14 is also communicable with the X-ray controller 24.

The graphic data former 21 is to form in real time graphic data representing a frame of the aperture of the limiting member 13a (hereinafter, referred to as limiting frame), in response to the aperture data supplied from the operating device 20

The image data comprising unit 22 is connected at its two inputs to the TV camera 17 and graphic data former 21 to receive the data of a surface image and graphic data of aperture frame, respectively. The image data composing unit 22 composes, into one frame data, image data through selecting, pixel by pixel, either one data between positionally corresponding two pixels of the frame data of and the surface image data supplied and send the composed image data in real time frame by frame to the TV monitor 23 to show the image data thereon.

On one hand, the X-ray controller 24 is able to communicate with the limiting member driving device 14 and to control the operation of the X-ray tube 11 in accordance with a given procedure.

The overall operation of the present embodiment will now be explained.

When the X-ray radiographic apparatus initiates its operation, the limiting member driving device 14 moves the limiting member 13a of the beam limiting device 13 to a position of a full aperture size as an initial state, thus its aperture is full open. In such a state, a partial surface image of a patient P is taken by the TV camera 17 through the limiting member 13 in full open. The image data thus-obtained is then sent to the image data composing unit 22.

The knob 20a of the operating device 20 is then adjusted by hand with the TV monitor 24 observed, so that a corresponding aperture size signal to an adjusted position of the knob 20a is sent to the graphic data former 21. In this former 21, a graphic data representing a frame specified by the aperture size signal is generated in real time and then supplied to the image data composing unit 22.

Therefore, the surface image data and frame graphic data are synthesized into a one frame data in real time in the composing unit 22. The composed image data are sent to the TV monitor 23 to display them thereon. Thus the TV monitor 23 displays an image shown in FIG. 3, for example, in which a limiting frame image FI represented by a square line is superimposed on a partial surface image SI of the patient P. Since the TV camera 17 is disposed at an optically conjugate position to the X-ray focal point FP, the size of frame image can be regarded as an X-ray radiation field for radiography which will be carried, based on an instruction from the X-ray controller 24.

In this situation, if the operator is unsatisfied with the size of the frame image now displayed on the TV monitor 23, he or she operates the knob 20a to readjust the size of the limiting frame image FI, corresponding to the aperture of the limiting member 13a. Readjusting the knob 20a permits the graphic data former 21 and image data composing unit 22 to display, in real time, an updated image on the TV monitor 23, in which a readjusted limiting frame image FI is superimposed on the partial surface image SI.

Accordingly, such readjustment will be repeated until a desired size of the limiting frame image FI appears on the TV monitor 23. In parallel with such adjustment, positioning of the X-ray tube 11 and patient P will be carried out so that a desired diagnostic portion of the patient P falls within the desired limiting frame image FI.

On having completed the above-mentioned positioning of the X-ray tube and patient and adjustment of the aperture size, a finally determined size of the aperture (i.e., a desired limiting frame image size, or a desired X-ray radiation field) is temporarily stored, as a target aperture size, in the memory of the limiting member driving device 14. In this stage, the actual aperture size of the limiting member 13a has been still fully open.

Then, an X-ray exposure switch (not shown) is pushed to give an instruction of exposure to the X-ray controller 24. In response to the exposure instruction, an aperture specifying signal SI is sent to the limiting member driving device 14, which reads out the target aperture size stores so far and control the actual aperture size of the limiting member 13a into the target value. After completing this actual control of the aperture size, the limiting member driving device 14 send a completion signal S2 back to the X-ray controller 24.

When receiving the completion signal S2, the X-ray controller 24 drives the X-ray tube 11, in the same fashion as conventional one, by giving it an X-ray exposure signal S3, thus causing the X-ray tube 11 to radiate X-ray beams toward the patient through the aperture of the limiting member 13a, whose aperture size has already been set into the target value.

In this way, while the actual aperture size is kept fully open, a desired target aperture size is adjusted and specified with a supposed image of a limiting frame superimposed on a partial surface image of a patient. Then, at the exposure stage of X-ray beams, the actual size is carried into the target value.

As a result, it is possible for an operator to observe the entire surface image FI taken by the TV camera 17 as well as the inside of the X-ray radiation field during the positioning and adjustment of the aperture. This means that, during the positioning and aperture adjustment, an operator can easily observe both of an exposed region and a non-exposed region at the same time and recognize the boundary between them. In consequence, an operator can more easily, efficiently and accurately carry out the positioning among the X-ray tube, patient and X-ray film and the adjustment of the aperture size of the X-ray beam limiting device, thereby offering remarkably improved efficiency of operation in preparation prior to X-ray exposure.

The improved operation will lead to a shortened examination time, which is, in particular, advantageous in mass screening.

Further, the amount of exposed X-ray beams can be kept to a minimum, as the area of an X-ray radiation field can be reduced down to its absolutely necessary region for examination.

In addition, even if the examination room is light, observing the TV monitor permits an operator to carry out the positioning and aperture adjustment as stated above. There is also no need to arrange the TV monitor alone in another dark room.

Further, because a lamp seen in the prior art is not used (i.e. lighting-up time is not concerned), there is no limitation in terms of times of positioning and aperture adjustment. This allows more precise positioning and aperture adjustment.

Still further, because light beams are not used, a patient does not receive dazzling light, the patient is relieved of this burden.

A second embodiment will now be explained with reference to FIGS. 4 to 6.

In this embodiment, the same reference numerals will be used to the same components as the first embodiment to simplify explanation. This simplified explanation manner will also be applied to all of the embodiments following after the second embodiment.

The X-ray radiographic apparatus shown in FIG. 4 comprises a monitor 40 having a touch panel 40a therein, an input device 41 such as a key board, a graphic data former 42, and a position calculator 43, instead of the operating device 20 and graphic data former 21 described before.

An operator is to select one arbitrary method of specifying an aperture limiting frame among several methods prepared beforehand, using the input device 41. In the present embodiment, there are provided three methods: the first method of specifying separately the positions of four segments composing a square limiting frame (refer to FIG. 5A), the second method of specifying the positions of arbitrary adjacent two segments of a square limiting frame (refer to FIG. 5B), and a third method of specifying the position of an arbitrary one corner point of a square limiting frame (refer to FIG. 5C). In case that the first method is selected from the input device 41, an operator is to specify four points by hand on the touch panel 40a, as shown in FIG. 5A. In case of the second method, an operator is to specify two points, as shown in FIG. 5B. In case of the third method, an operator is to specify one point, as shown in FIG. 5C. The touch panel 40A of the monitor 40 functions as a coordinate input means.

The graphic data former 42 receives a signal representing the specifying method of an aperture limiting frame from the input device 41 and a positional signal from the touch panel 40a. The graphic data former 42 forms and generates graphic data of an limiting aperture frame according to the received signals. When the second specifying method has been selected, the remaining segments, which are face-to -face to the two adjacent segments manually given, is automatically specified at symmetrical positions to the segments according to the manually-specified points. Further, when the third specifying method has been selected, the remaining three corner points are automatically determined at the symmetrical positions to the manually specified corner point. The graphic data thus-formed are sent to both of the position calculator 43 and the image data composing unit 22.

The position calculator 43 calculates the positions blades of the limiting member 13a correspondingly to the graphic data representing an aperture limiting frame specified by hand. The newest calculated position data is stored as its target value in a memory of the calculator 43.

Accordingly, in the same manner as the first embodiment, the limiting member 13a is fully opened at first by the limiting member driving device 14. The TV camera 17 photographs a partial surface portion of a patient P and its surface image SI is displayed on the monitor 41, as shown in FIG. 6.

Then, an operator selects one of the specifying methods of the limiting frame through the input device 41 and, according to the selected method, gives positional information to the touch panel 40a. In consequence, graphic data of a desired limiting frame are formed in the graphic data former 42, the formed graphic data of the limiting frame being sent via the composing unit 22 to the monitor 40. As a result, the Limiting frame image FI is displayed superimposedly on the surface image SI, as represented in FIG. 6, which exemplify a case of the third specifying method.

The size of the limiting frame displayed on the monitor 41 can be changed in real time in response to specification on the touch panel 40a. Therefore, the operator can place a limiting frame image FI of an arbitrary size on the screen of the monitor 41.

Since the area of a limiting frame image FI shows an X-ray radiation field, positioning of the X-ray tube 11 and patient P is performed in such a manner that a desired diagnostic region is put within a finally-specified limiting frame image FI. At this time, the position data of the blades of the limiting member 13a, which corresponds to the finally-specified limiting frame, has been calculated and stored as a target value in the position calculator 43. The procedure of the aperture adjustment and positioning can be repeated, if required, and their performance orders can be opposite.

Further, in response to a start of X-ray exposure, an aperture specifying signal S1 is sent from the X-ray controller 24 to the limiting member driving device 14, thereby all of the blades of the limiting member 13a is adjusted to its desired position providing a desired aperture size, according to the read-out target value from the position calculator 43. On a completion signal S2 being returned to the X-ray controller 24, X-ray exposure begins by sending an X-ray exposure signal S3 to the X-ray tube 11, as explained in the first embodiment.

As apparent from the above, the second embodiment uses the touch panel to directly specify a region corresponding to a desired X-ray radiation field on a monitor. The size of the region can be changed directly on a monitor. Further, according to an operator's will, the most convenient method of specifying a limiting frame image on a monitor may be selected.

Therefore, the second embodiment offer not only the equivalent advantages to the first embodiment but remarkably improved operation for specifying the size of an aperture.

In this embodiment, although a square aperture has been explained, if an aperture is circular, there can be provided another variations; for example, three point data to pass a circle are given on a monitor or a combined data of a central point and a radius for determining a circle is given on a monitor.

By the way, although the above embodiments have been applied to the X-ray radiographic apparatus having an X-ray tube of one focal point, the present invention is also applicable to stereoradiography using an X-ray tube of two X-ray focal points. Such embodiments will be followed.

A third embodiment of the present invention will now be described with reference to FIGS. 7 and 8.

An X-ray radiographic apparatus shown in FIG. 7 comprises an X-ray tube 50 having two focal points FPl and FPr each radiating X-ray beams toward a patient P and an X-ray beam limiting device 51 incorporating a pair of limiting member 51l and 51r limiting the X-ray beams radiated from the two X-ray focal points FPl and FPr. Each of the limiting members 51l and 51r forms an aperture adjustable. At optically conjugate positions to the X-ray focal points FPl and FPr in the X-ray limiting device 51, there are two TV cameras 52l and 52r for each photographing partial surface images of the patient P through the apertures made by the limiting member 51l and 51r. Mirrors 53l and 53r are each disposed on the way of the X-ray beam paths to penetrate the X-ray beams and reflect light beams from the patient P to the TV cameras 52l and 52r through the apertures of the limiting members 52l and 51r, respectively. The TV cameras 52l and 52r are each connected to monitors 54l and 54r placed in a console, for instance.

In this embodiment, light beams reflected on the patient P travel via the apertures of the limiting members 51l and 51r to the mirrors 53l and 53r, respectively. The light beams reflect at the mirrors 53l and 53r and are admitted to the TV cameras 52l and 52r, respectively. Thus, the regions of partial images displayed by the monitors 54l and 54r equal to X-ray radiation fields in such a case that X-ray beams are radiated from the focal points FPl and FPr.

Therefore, while observing surface images on the screen of the monitors 54l and 54r (refer