Stereoscopic X-ray imaging apparatus

1. Field of the Invention

The present invention relates to a stereoscopic X-ray imaging apparatus.

2. Description of the Related Art

A stereoscopic X-ray imaging apparatus has an advantage of being capable of recognizing an anteroposterior relationship of a plurality of blood vessels. The stereoscopic X-ray imaging apparatus is configured to avoid unnecessary radiation exposure for an object (subject). Japanese Patent Application Laid-Open No. 2011-72369 discloses a configuration in which a three-dimensional position of a biopsy region is calculated based on two X-ray images obtained by stereoscopic imaging. Based on the calculated three-dimensional position of the biopsy region and a stereoscopic angle of a radiation source, a new X-ray radiation field is calculated. Japanese Patent Application Laid-Open No. 2010-233875 discloses a configuration in which an X-ray radiation field is controlled by a collimator to stay within a predetermined range. Japanese Patent Application Laid-Open No. 2010-115270 discloses a configuration in which a plurality of slits, through which an X-ray passes, is two-dimensionally formed in a collimator, and a size and a position of the plurality of slits are controlled.

In the X-ray imaging apparatus according to the related art having a stationary X-ray source (X-ray focus) and a stationary X-ray sensor, a position of each of the right and left X-ray sources for stereoscopic imaging is clear. Therefore, it is not necessary to distinguish between the radiation fields of the right and left X-ray sources. However, in an X-ray imaging apparatus having an X-ray source movable relative to an X-ray sensor, a three-dimensional positional relationship between the X-ray source and the X-ray sensor may not always be clear. For this reason, especially in stereoscopic X-ray imaging, it is necessary to set an appropriate angle of convergence and avoid the unnecessary radiation exposure due to a difference between the right and left X-ray radiation fields. Thus, a unit for appropriately and conveniently adjusting the positional relationship between the right and left X-ray sources is necessary for performing the effective stereoscopic X-ray imaging.

An exemplary object of the present invention for solving the above problem is to provide a stereoscopic X-ray imaging apparatus capable of appropriately and conveniently adjusting a positional relationship between right and left X-ray sources in stereoscopic X-ray imaging.

To solve the above problem, the present invention includes: a plurality of X-ray sources; a diaphragm unit in which a plurality of openings is formed, X-rays radiated by the plurality of X-ray sources passing through the plurality of openings, respectively; an X-ray sensor on which the X-ray radiated by each of the plurality of X-ray sources is projected; a controller configured to control positions and sizes of the plurality of openings; and a plurality of visible light sources configured to radiate a visible light to the X-ray sensor in the same area as each of the plurality of X-ray sources through each of the plurality of openings. Spectra of the visible light emitted by the plurality of visible light sources are different from each other.

Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).

FIG. 1 is a schematic external view of a configuration of a stereoscopic X-ray imaging apparatus according to a first embodiment of the present invention;

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

FIG. 3 is a schematic cross-sectional view of a configuration of a stereoscopic X-ray generating unit;

FIGS. 4A to 4C are schematic cross-sectional views illustrating a relationship between a distance (imaging distance) from right and left X-ray tubes to a surface of an X-ray sensor, and a position and a size of a visible light projection field (X-ray radiation field);

FIG. 5 is a schematic block diagram illustrating a configuration of a stereoscopic X-ray imaging apparatus according to a second embodiment;

FIG. 6A is a schematic view illustrating a condition in which an “appropriate stereoscopic diaphragm distance” is smaller than an actual imaging distance, and an exemplary visible light image imaged by a visible light imaging unit in such a condition;

FIG. 6B is a schematic view illustrating a condition in which an “appropriate stereoscopic diaphragm distance” is larger than an actual imaging distance, and an exemplary visible light image imaged by the visible light imaging unit in such a condition; and

FIG. 7 is a block diagram of a stereoscopic X-ray imaging apparatus according to a third embodiment.

First Embodiment

First, a configuration of a stereoscopic X-ray imaging apparatus 100 a according to a first embodiment of the present invention is described herein with reference to FIGS. 1 and 2 . FIG. 1 is a schematic external view of the configuration of the stereoscopic X-ray imaging apparatus 100 a according to the first embodiment of the present invention. FIG. 2 is a block diagram of the stereoscopic X-ray imaging apparatus 100 a according to the first embodiment of the present invention. As in FIGS. 1 and 2 , the stereoscopic X-ray imaging apparatus 100 a includes an operating unit 11 , a controller 10 , a stereoscopic X-ray generating unit 12 , an X-ray sensor 14 , and a stereoscopic displaying unit 15 .

The operating unit 11 is a unit to be used by an operator for operating the stereoscopic X-ray imaging apparatus 100 a . The operating unit 11 includes an operating member (e.g., operation panel) to be operated by the operator, and a displaying unit (e.g., display panel) for displaying an operation menu. The operating unit 11 further includes a function of a stereoscopic distance displaying unit 111 for displaying an “appropriate stereoscopic diaphragm distance D j ”. Details of the “appropriate stereoscopic diaphragm distance D j ” will be described later.

The controller 10 , in response to an operation of the operating unit 11 by the operator, controls the stereoscopic X-ray imaging apparatus 100 a (the stereoscopic X-ray generating unit 12 , the X-ray sensor 14 , and the stereoscopic displaying unit 15 ). The controller 10 is a computer having a CPU for performing predetermined arithmetic processing, and a storage device for storing a program and various data. The CPU of the controller 10 executes control of the stereoscopic X-ray imaging apparatus 100 a by reading and executing the program from the storage device.

The stereoscopic X-ray generating unit 12 generates a stereoscopic X-ray, and radiates the generated stereoscopic X-ray to an object P and a surface of the X-ray sensor 14 . Details of the stereoscopic X-ray generating unit 12 will be described later.

The X-ray sensor 14 receives the X-ray (X-ray that has passed through the object P) radiated by the stereoscopic X-ray generating unit 12 , and converts the received X-ray into an image signal (electric signal). The image signal converted by the X-ray sensor 14 is sent to the controller 10 , and predetermined image processing is performed thereon in the controller 10 . The image signal, on which the predetermined image processing has been performed, is further sent to the stereoscopic displaying unit 15 .

The stereoscopic displaying unit 15 stereoscopically displays the image signal sent from the controller 10 . The stereoscopic displaying unit 15 includes the display panel, which can display an image.

Next, a configuration of the stereoscopic X-ray generating unit 12 is described with reference to FIG. 3 . FIG. 3 is a schematic cross-sectional view illustrating the configuration of the stereoscopic X-ray generating unit 12 . As in FIG. 3 , the stereoscopic X-ray generating unit 12 includes: (a plurality of) right and left X-ray tubes 121 R and 121 L, (a plurality of) right and left visible light sources 127 R and 127 L, (a plurality of) right and left X-ray transmissive mirrors 128 R and 128 L, and a diaphragm unit 122 (collimator). Each of the (plurality of) right and left X-ray tubes 121 R and 121 L is an X-ray source (X-ray focus), which alternately radiates the X-ray. Each of the (plurality of) right and left visible light sources 127 R and 127 L emits a visible light. The (plurality of) right and left X-ray transmissive mirrors 128 R and 128 L are disposed on paths of the X-rays radiated by the right and left X-ray tubes 121 R and 121 L, respectively. Then, the right and left X-ray transmissive mirrors 128 R and 128 L transmit the X-rays radiated by the right and left X-ray tubes 121 R and 121 L, and reflect the visible light emitted by the right and left visible light sources 127 R and 127 L, respectively. Note that the right and left visible light sources 127 R and 127 L are disposed at conjugate positions relative to the right and left X-ray tubes 121 R and 121 L, respectively.

The diaphragm unit 122 (collimator) defines a range of the X-ray radiated by each of the right and left X-ray tubes 121 R and 121 L. In the diaphragm unit 122 , right and left inner blades 123 R and 123 L and right and left outer blades 124 R and 124 L are movably provided for blocking the X-ray. A right opening 125 R is formed between the right inner blade 123 R and the right outer blade 124 R. A left opening 125 L is formed between the left inner blade 123 L and the left outer blade 124 L. The X-ray and the visible light can pass through the right and left openings 125 R and 125 L. Positions and sizes of right and left X-ray radiation fields G R and G L (areas irradiated with X-ray radiation) and positions and sizes of right and left visible light projection fields F R and F L (areas irradiated with visible light radiation) are determined by positions and sizes of the right and left openings 125 R and 125 L. The operator can change the positions and the sizes of the right and left openings 125 R and 125 L by moving and positioning the right and left inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L. Accordingly, the operator can adjust positions and ranges of the right and left X-ray radiation fields G R and G L , and positions and ranges of the visible light projection fields F R and F L .

Note that the diaphragm unit 122 is provided with a driving mechanism for driving the right and left inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L. This driving mechanism is controlled by the controller 10 . Therefore, the operator can adjust the positions and the ranges of the right and left X-ray radiation fields G R and G L by operating the operating unit 11 . In addition, it is also possible to configure the right and left inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L to be manually operated by the operator in the moving and positioning thereof.

The X-rays radiated by the right and left X-ray tubes 121 R and 121 L transmit the right and left X-ray transmissive mirrors 128 R and 128 L, respectively. The X-ray is shaped by the diaphragm unit 122 , and reaches the surface of the X-ray sensor 14 . The visible light emitted by the right and left visible light sources 127 R and 127 L is reflected by the right and left X-ray transmissive mirrors 128 R and 128 L, respectively. The visible light is shaped by the diaphragm unit 122 , and reaches the X-ray sensor 14 . As described above, the right and left X-ray tubes 121 R and 121 L, and the right and left visible light sources 127 R and 127 L are disposed at the conjugate positions. Therefore, the X-ray radiation fields G R and G L correspond with the visible light projection fields F R and F L . Thus, by visually recognizing the positions and the ranges of the right and left visible light projection fields F R and F L , the operator can check the positions and the ranges of the right and left X-ray radiation fields G R and G L . Then, the operator adjusts positions of the right and left inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L so that the right and left visible light projection fields F R and F L overlap (correspond) with each other on the surface of the X-ray sensor 14 .

A spectrum of the visible light emitted by each of the right and left visible light sources 127 R and 127 L is different from each other. According to such a configuration, the operator can easily distinguish between the visible light projection fields F R and F L of the right and left visible light sources 127 R and 127 L. Thus, it becomes easier to adjust the positions and the sizes of the right and left X-ray radiation fields G R and G L . In addition, a configuration is also possible in which a filter is disposed on a path of the visible light in or near the diaphragm unit 122 . Each filter transmits the visible light having a spectrum different from each other. Such a configuration also enables the operator to easily distinguish between the visible light projection fields F R and F L of the right and left visible light sources 127 R and 127 L.

Note that in the case of using an anti-scatter grid having a specified grid distance, the operator moves the right and left inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L so that the “appropriate stereoscopic diaphragm distance D j ” equals the grid distance. At this time, the operator moves the right and left inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L while checking the “appropriate stereoscopic diaphragm distance D j ” displayed on the stereoscopic distance displaying unit 111 . In this way, the positions and the sizes of the right and left visible light projection fields F R and F L can be adjusted to overlap (correspond) with each other on the surface of the X-ray sensor 14 .

As in FIG. 3 , the right and left openings 125 R and 125 L are symmetrically configured about a center line C, which runs in the middle of the right and left X-ray tubes 121 R and 121 L (right and left X-ray foci). In other words, the openings 125 R and 125 L of the same size are formed at positions symmetrical about the center line C. In order to realize such a configuration, the inner blades 123 R and 123 L are disposed at the positions symmetrical about the center line C, and move the same distance in opposite directions simultaneously or in a linked manner. Likewise, the right and left outer blades 124 R and 124 L are also disposed at the positions symmetrical about the center line C, and move the same distance in opposite directions simultaneously or in a linked manner. Note, however, that the moving distance of the inner blades 123 R and 123 L is different from the moving distance of the outer blades 124 R and 124 L. In a configuration in which the controller 10 controls the diaphragm unit 122 , the controller 10 drives the right and left inner blades 123 R and 123 L to move them over the same distance in the opposite directions from each other, and also drives the right and left outer blades 124 R and 124 L to move them over the same distance in the opposite directions from each other. Furthermore, in a configuration in which the operator manually adjusts the diaphragm unit 122 , a configuration may be applied in which the right and left inner blades 123 R and 123 L are linked by a linkage mechanism, and the right and left outer blades 124 R and 124 L are also linked by the linkage mechanism. Then, when the operator manually moves either one of the right and left inner blades 123 R and 123 L, the other of the right and left inner blades 123 R and 123 L moves the same distance in the opposite direction by the linkage mechanism. Likewise, when the operator manually moves either one of the right and left outer blades 124 R and 124 L, the other of the right and left outer blades 124 R and 124 L moves the same distance in the opposite direction by the linkage mechanism. With such a configuration, the right and left openings 125 R and 125 L have the same size, and are formed at positions symmetrical about the center line C.

Next, control of the right and left openings 125 R and 125 L is described with reference to FIGS. 4A to 4C . FIGS. 4A to 4C are schematic cross-sectional views illustrating a relationship between a distance (imaging distance) from the right and left X-ray tubes 121 R and 121 L to the surface of the X-ray sensor 14 , and the positions and the sizes of the visible light projection fields F R and F L (X-ray radiation fields G R and G L ).

The operator adjusts the positions and the sizes of the right and left X-ray radiation fields G R and G L by changing the positions and the sizes of the right and left openings 125 R and 125 L. Note that the right and left X-ray tubes 121 R and 121 L are not used for adjusting the positions and the sizes of the right and left X-ray radiation fields G R and G L , but the right and left visible light sources 127 R and 127 L are used. As described above, the positions and the sizes of the right and left visible light projection fields F R and F L and the positions and the sizes of the right and left X-ray radiation fields G R and G L are the same. Therefore, the positions and the sizes of the right and left X-ray radiation fields G R and G L are adjusted by adjusting the positions and the sizes of the right and left visible light projection fields F R and F L .

FIG. 4A is a schematic view illustrating a condition in which the imaging distance (SDD: Source Detector Distance) is D 1 and the “appropriate stereoscopic diaphragm distance D j ” is adjusted to D 1 . Here, the “appropriate stereoscopic diaphragm distance D j ” refers to an imaging distance in which the right and left X-ray radiation fields G R and G L overlap (correspond) with each other on the surface of the X-ray sensor 14 . The “appropriate stereoscopic diaphragm distance D j ” changes with the positions and the sizes of the openings 125 R and 125 L in the diaphragm unit 122 . Thus, the operator can change the “appropriate stereoscopic diaphragm distance D j ” by changing the positions and the sizes of the openings 125 R and 125 L in the diaphragm unit 122 (by moving the inner blades 123 R and 123 L and the outer blades 124 R and 124 L). The operator changes the “appropriate stereoscopic diaphragm distance D j ” to correspond with the actual imaging distance. Accordingly, the stereoscopic X-ray imaging can be performed in an appropriate condition.

In a condition illustrated in FIG. 4A , the right and left visible light projection fields F R and F L (right and left X-ray radiation fields G R and G L ) overlap with each other on the surface of the X-ray sensor 14 . Furthermore, in this condition, the visible light radiated by the right and left visible light sources 127 R and 127 L irradiates the object P entirely. In such a condition, the stereoscopic distance displaying unit 111 displays D 1 as the “appropriate stereoscopic diaphragm distance D j ”. Note that the relationship between the positions and the sizes of the right and left openings 125 R and 125 L (positions of the inner blades 123 R and 123 L and the outer blades 124 R and 124 L) and the “appropriate stereoscopic diaphragm distance D j ” is stored in the controller 10 . Then, when the diaphragm unit 122 is operated by the operator, the controller 10 detects (or calculates, based on the amount of movement) the positions and the sizes of the openings 125 R and 125 L. Then, the controller 10 reads the “appropriate stereoscopic diaphragm distance D j ” corresponding to the detected (or calculated) positions and sizes, and displays the distance on the stereoscopic distance displaying unit 111 .

FIG. 4B is a schematic view illustrating a condition in which the imaging distance is changed to a distance D 2 (D 2 <D 1 ), which is smaller than the “appropriate stereoscopic diaphragm distance D j ”, when the “appropriate stereoscopic diaphragm distance D j ” is adjusted to D 1 . As in FIG. 4B , when the imaging distance becomes smaller than the “appropriate stereoscopic diaphragm distance D j ”, the right and left visible light projection fields F R and F L (right and left X-ray radiation fields G R and G L ) are shifted either to the right or left on the surface of the X-ray sensor 14 . Furthermore, on the object P, there is an area on which only the visible light from either one of the right and left visible light sources 127 R and 127 L is radiated, and not the visible light from the other (hatched areas in FIG. 4B ). It is not possible to stereoscopically view this area. In this way, unnecessary radiation exposure (exposure not contributing to a stereoscopic view) occurs on the object P.

Therefore, as in FIG. 4C , the controller 10 or the operator adjusts the “appropriate stereoscopic diaphragm distance D j ” to be equal to the actual imaging distance. FIG. 4C illustrates a condition in which the “appropriate stereoscopic diaphragm distance D j ” is adjusted to D 2 when the imaging distance is D 2 . As in FIG. 4C , when the “appropriate stereoscopic diaphragm distance D j ” and the actual imaging distance are the same, the X-ray is radiated on the object P entirely from both of the right and left X-ray tubes 121 R and 121 L. Therefore, it is possible to stereoscopically view the entire object P. Furthermore, no unnecessary radiation exposure occurs on the object P.

Second Embodiment

Next, a second embodiment of the present invention is described. The first embodiment is a configuration in which an operator adjusts positions and ranges of the visible light projection fields F R and F L on the surface of the X-ray sensor 14 . On the other hand, the second embodiment is a configuration in which a stereoscopic X-ray imaging apparatus 100 b automatically performs an adjustment. FIG. 5 is a schematic block diagram of the configuration of the stereoscopic X-ray imaging apparatus 100 b according to the second embodiment. Note that any part of the configuration common with the first embodiment is denoted with the same reference numeral and the description thereof is omitted (see FIG. 2 ). As in FIG. 5 , the stereoscopic X-ray imaging apparatus 100 b includes a visible light imaging unit 16 (visible light image capturing unit). The visible light imaging unit 16 (visible light image capturing unit) is capable of imaging a visible light image (a composition image of the right and left visible light projection fields F R and F L ) projected onto a surface of the X-ray sensor 14 . Various cameras with sensitivity to a visible light range are applicable as the visible light imaging unit 16 (visible light image capturing unit). Note that the visible light imaging unit is disposed, for example, in the stereoscopic X-ray generating unit 12 so as to image the visible light image projected onto the surface of the X-ray sensor 14 . Note, however, that a specific position to dispose the visible light imaging unit 16 is not limited as long as it is capable of imaging the visible light image projected onto the surface of the X-ray sensor 14 .

FIG. 6A is a schematic view illustrating a condition in which the “appropriate stereoscopic diaphragm distance D j ” is smaller than an actual imaging distance D L , and an exemplary visible light image I L imaged by the visible light imaging unit 16 in such a condition. FIG. 6B is a schematic view illustrating the condition in which the “appropriate stereoscopic diaphragm distance D j ” is larger than an actual imaging distance D s , and an exemplary visible light image I s imaged by the visible light imaging unit 16 in such a condition.

A method of adjusting positions of the right and left X-ray radiation fields G R and G L in the stereoscopic X-ray imaging apparatus 100 b according to the second embodiment is as follows.

First, by an operation of an operating unit by an operator, a controller 10 turns on the right and left visible light sources 127 R and 127 L. Accordingly, a visible light is radiated on the surface of the X-ray sensor 14 , and a visible light image is formed thereon (right and left visible light projection fields F R and F L are combined). Then, the visible light imaging unit 16 images the visible light image formed on the surface of the X-ray sensor 14 , and sends the imaged visible light image to the controller 10 . The controller 10 determines a condition of overlapping between the right and left visible light projection fields F R and F L in the visible light image. Then, based on the determination result of the condition of overlapping, the controller 10 drives the diaphragm unit 122 to adjust the “appropriate stereoscopic diaphragm distance D j ”.

Specifically, as in FIG. 6A , in a case where a side-to-side positional relationship of the right and left visible light sources 127 R and 127 L and the side-to-side positions of the right and left visible light projection fields F R and F L in the visible light image are reversed, the “appropriate stereoscopic diaphragm distance D j ” is smaller than the actual imaging distance. Therefore, in this case, the controller 10 drives the right and left inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L to increase the “appropriate stereoscopic diaphragm distance D j ”. On the other hand, as in FIG. 6B , in a case where the positions of the right and left visible light sources 127 R and 127 L and the right and left positions of the right and left visible light projection fields F R and F L in the visible light image are not reversed, the “appropriate stereoscopic diaphragm distance D j ” is larger than the actual imaging distance. Therefore, in this case, the controller 10 drives the right and left inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L to decrease the “appropriate stereoscopic diaphragm distance D j ”.

Then, the controller 10 repeatedly executes determination of the condition of overlapping between the visible light projection field F R and F L in the visible light image, and a change of the “appropriate stereoscopic diaphragm distance D j ”. Accordingly, the controller 10 can converge the “appropriate stereoscopic diaphragm distance D j ” to the actual imaging distance.

Note that the controller 10 may also be configured to adjust the imaging distance to converge into the “appropriate stereoscopic diaphragm distance D j ” by driving and moving the stereoscopic X-ray generating unit 12 or the X-ray sensor 14 .

Third Embodiment

Next, a third embodiment of the present invention is described. The first and second embodiments assume a case where an imaging distance is not clear. On the other hand, in the third embodiment, a stereoscopic X-ray imaging apparatus 100 c includes a distance detecting unit 130 for measuring the imaging distance.

FIG. 7 is a block diagram of the stereoscopic X-ray imaging apparatus 100 c according to the third embodiment. Note that any part of the configuration common with the first embodiment is denoted with the same reference numeral and the description thereof is omitted. As in FIG. 7 , a stereoscopic X-ray generating unit 12 includes the distance detecting unit 130 and an attitude detecting unit 131 . The distance detecting unit 130 detects the actual imaging distance, and sends the detected result to a controller 10 . Various publicly-known non-contact range finders, for example, are applicable as the distance detecting unit 130 . The attitude detecting unit 131 detects an attitude of the stereoscopic X-ray generating unit 12 , and sends the detected result to the controller 10 . Various publicly-known gyro sensors are applicable as the attitude detecting unit 131 . Based on the detected result of the attitude by the attitude detecting unit 131 , the controller 10 corrects the imaging distance detected by the distance detecting unit 130 .

Then, the controller 10 compares the imaging distance detected by the distance detecting unit 130 (may be a corrected imaging distance) and a currently-set “appropriate stereoscopic diaphragm distance D j ”. Then, the controller 10 drives the diaphragm unit 122 in order to adjust the “appropriate stereoscopic diaphragm distance D j ” to be equal to the imaging distance detected by the distance detecting unit 130 .

Fourth Embodiment

Next, a fourth embodiment of the present invention is described with reference to FIG. 3 . The first to third embodiments are configured to change the stereoscopic diaphragm distance. On the other hand, the fourth embodiment is configured to adjust positions and the sizes of right and left X-ray radiation fields G R and G L by changing an angle of convergence θ of an X-ray radiated by right and left X-ray tubes 121 R and 121 L. The configuration of the stereoscopic X-ray imaging apparatus according to the fourth embodiment is different from the configuration according to the first embodiment in that the stereoscopic distance displaying unit 111 is replaced by a convergence angle displaying unit. The convergence angle displaying unit displays the appropriate angle of convergence. The appropriate angle of convergence means an angle of convergence in which the X-ray can be radiated so that the right and left X-ray radiation fields G R and G L overlap (correspond) with each other, and no unnecessary radiation exposure occurs. Note that any other configuration is common with the first embodiment.

As in FIG. 3 , a controller 10 can change the angle of convergence θ by controlling the right and left inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L. In the controller 10 , a relationship between the angle of convergence θ and positions of the right and left inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L is stored. An operator specifies the angle of convergence θ by operating an operating unit 11 . By doing so, the controller 10 reads the positions of the inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L corresponding to the angle of convergence θ specified by the operator, and moves the inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L to the positions that have been read. In this way, the controller 10 adjusts the angle of convergence θ by driving the inner blades 123 R and 123 L and the right and left outer blades 124 R and 124 L. In such a configuration, the positions and the sizes of the right and left X-ray radiation fields G R and G L can be adjusted. Note that, as in FIG. 3 , a distance between the right and left X-ray tubes 121 R and 121 L does not change. Therefore, the controller 10 changing the angle of convergence of the X-ray radiated by the right and left X-ray tubes 121 R and 121 L and the controller 10 changing the imaging distance have the same meaning.

Other Embodiments

Embodiments of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions recorded on a storage medium (e.g., non-transitory computer-readable storage medium) to perform the functions of one or more of the above-described embodiment(s) of the present invention, and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more of a central processing unit (CPU), micro processing unit (MPU), or other circuitry, and may include a network of separate computers or separate computer processors. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2012-124101, filed May 31, 2012, which is hereby incorporated by reference herein in its entirety.