JPH064068B2 - Tomography equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a parallel imaging method for photographing a subject existing on a predetermined cutting plane in each of the standing, tilted, horizontal and reverse tilted positions of a subject. The present invention relates to a tomographic X-ray imaging apparatus using a plane movement method.

[Conventional technology]

The tomographic X-ray imaging apparatus includes a parallel plane moving method in which the X-ray tube and the film move along straight lines parallel to each other, and an arc moving method in which the both move along an arc.

FIG. 4 is a schematic view showing a typical mechanism of the parallel plane moving system, which is a column (3) holding the X-ray tube (1) and diaphragm (2) at the upper end.
0) is its base, and the cut surface X along with the film holding portion (10).
-Move along the guide rail (9) parallel to X,
The X-ray tube (1) is connected to the X-ray tube device (1) (2) and the film holding unit (10) via a connecting rod (oscillating rod) (31).
The focal point (F) and the film center (f) are arranged so as to sandwich the cutting center (0) and make linear motions parallel to the cutting plane (XX), respectively, and the cutting center (0) is connected to the connecting rod. It coincides with the swing center of (31).

In this parallel plane moving system, the X-ray tube focus
(F) Since the distance between the films can be made large and the distance between the top plate (8) surface and the film can be made small on the contrary, a tomographic image with less geometric blur caused by the size of the focus can be obtained. However, there are the following issues as problems.

That is, as the tomographic angle (2α) increases, the traverse distance of the support column (30) increases. Therefore, when the front size of the device is limited, the tomographic imaging range cannot be large, and the top plate (8) ), A subject having a predetermined cutting plane in each body position of the subject is imaged in an image in a position other than the horizontal position of the subject.
A connecting rod (3) connecting (1) and (2) to the film holding portion (10).
In (1), the moment due to its own weight or a part thereof is generated at its swing center (0) from the X-ray tube devices (1), (2) and the film holding part (10), and this is canceled. Therefore, if the balance weight is incorporated, the mechanism becomes complicated.

FIG. 5 is a schematic explanatory view showing a mechanism of an arc moving method, but since the distance between the X-ray tube focus (F) and the film is kept constant during the movement of both, the subject is placed on the film surface. Although the image can be taken at a constant density and the mechanism is simpler than that of the apparatus of the parallel plane moving system, there is a problem that blurring increases as the tomographic angle (2α) increases.

[Problems to be Solved by the Invention] The present invention has a problem in the conventional parallel plane moving type tomographic X-ray imaging apparatus, that is, when the front size of the apparatus is limited, the tomographic imaging range is set large. It is difficult to balance the weight around the swing center of the connecting rod that connects the X-ray tube device and the film holding unit in the tomographic imaging of the subject and the subject other than the horizontal position. The present invention was made in order to solve a certain point, and a substantially parallel plane moving method is adopted while adopting a simple structure by adopting a structure similar to an arc moving method for a holding mechanism of an X-ray tube device. It is an object of the present invention to provide a tomographic X-ray imaging apparatus which operates as described above and solves the above problems.

[Means for solving problems]

According to the present invention, a tomographic X-ray apparatus is configured as follows as a technical means for solving the above-mentioned problems. That is, an X-ray tube device including an X-ray tube (1) and a diaphragm (2)
(1), (2) and the X-ray tube device (1), (2) support arm (3)
Upper stanchion (4) to hold it through the base and the base fixed to the floor
(5) and a turntable plate rotatably supported on the base (5)
(6) and the frame (7) fixed to the rotating base plate (6)
And the top plate (8) engaged with the frame (7) so as to be able to move up and down
A guide rail (9) fixed to the top plate (8) on the frame (7), a film holding portion (10) which is linearly moved by being guided by the guide rail (9), and a film holding portion. The lower strut (11) holding the portion (10) at the lower end, and the upper strut (4) and the lower strut (11) are slidably engaged with each other with their longitudinal axes aligned. A tomographic X-ray apparatus comprising a hollow column (12) swingably engaged with the frame (7), wherein the upper column (4)
A rack (13) diagonally across the swing center (0) of the hollow support column (12) and parallel to the longitudinal direction of the support columns (4) and (11) in each of the lower support column (11) and the lower support column (11). , (14) are fixed, and the gears (1) that engage with these racks (13), (14) respectively.
5), (16), the upper part of the hollow column (12), fixed to the rotating shaft (20), (21) rotatably attached to the lower part, respectively,
The mutual tooth ratio of these gears (15) and (16) is adjusted so that the focal point (F) of the X-ray tube devices (1) and (2) at the neutral position of the X-ray imaging system.
And the line segment connecting the film center (f) of the film holder (10)
Internal division ratio where (▲ ▼) is internally divided by the swing center (0)
Is equal to (▲ / ▼), and the rotation axis (20), (2
1) is connected to each other via a rotation transmission member so as to rotate by the same rotation angle.

Further, the swinging center (0) of the hollow column (12) is located between the focal point (F) of the X-ray tube (1) and the film center (f) of the film holding unit (10) at the neutral position of the X-ray imaging system. Connect the line segment (▲ ▼)
The X-ray tube devices (1) and (2) and the film holding unit (10) are internally divided by their weights (W ₁ ) and (W ₂ ), respectively.

[Work]

Since the tomographic X-ray apparatus according to the present invention is configured as described above, it operates as follows.

Assuming that the hollow strut (12) is moved with respect to the frame (7) from its neutral position to the swing position with a deflection angle of, for example, 20 °, the film holding unit (10) is moved during this period.
Is moved along the guide rail (9),
(f) and the focus (F) of the X-ray tube (1) are (f '),
Move to (F '). As shown in FIG. 3, when ▲ ▼ = m, ▲ ▼ '= m', and the lower support column (11) is m '.
-M = Δm is pulled out from the hollow column (12). Since this pull-out length is the same as the movement amount of the rack (14), the rotation transmission to the rotation shaft (22) is performed as it is as the rotation angle (β) of the gear (16) that meshes with the rack (14), that is, the rotation shaft (21). It is transmitted through the member. Therefore, the gear (15) has a rotation angle (β)
Only by rotating it, the rack (13) that engages with it is moved upward, and the upper support column (4) is pushed out from the hollow support column by a little length accordingly. Now if ▲ ▼ = 1,
Since the swing center (0) is a fixed point, l / m = c
(Constant). The gear ratio of gears (15) and (16) is 1 / m.
= C is set, so the above upper support
The extrusion of (4) is Δl = m · c. By the way, F'O =
If l ′, then l ′ / m ′ = (l + Δm · c) / (m + Δm)
= C (m + Δm) / (m + Δm) = c, and it is clear that the focal point (F) of the X-ray tube (1) operates according to the parallel plane moving method.

Further, the swing center (0) is the line segment (Ff)
(1), (2) own weight (W ₁ ), film holding part (10) own weight (W ₂ )
If it is set to a point that is internally divided in inverse proportion to, by rotating the rotation base plate (6), the subject placed on the top plate (8) is allowed to stand. When performing the tomography, the weights (W ₁ ) and (W ₂ ) of the X-ray tube devices (1) and (2) and the film holding unit (10) with respect to the swing center (0), respectively. The moments W ₁ · 1, W ₂ · m acting from are the same in magnitude,
Since the directions are opposite, the weight balance around the cutting center (0) is automatically taken. This is the same when photographing in other postures.

〔Example〕

An apparatus according to an embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an external front view of the apparatus of this embodiment, and FIG. 2 is an external side view thereof.

An X-ray tube device including an X-ray tube (1) and a diaphragm (2) is held by a support arm (3) on an upper column (4) having a rectangular cross section.

On a base (5) fixed to the floor surface, a top plate (8) on which a subject is placed is attached via a lifting mechanism (not shown).
A rotating base plate (6), which is held in a cantilevered manner, has a frame (7) having an L-shaped side surface, which is held so as to be always parallel to the longitudinal direction thereof, is rotatably engaged.

The film holding part (10) is engaged with a guide rail (9) arranged in the frame (7) in parallel with the longitudinal direction of the top plate (8) and has a cross-sectional shape of an upper strut ( It is held at the lower end of a lower column (11) of the same shape as 4) via a support arm (10 ') rotatably engaged with it. The upper strut (4) and the lower strut (11) are slidably engaged with the rectangular hollow strut (12) through a plurality of pairs of guide rollers so that their longitudinal axes coincide with each other. The square hollow column (12) has a support shaft (12 ') fixed to it.
It is rotatably supported by the frame (7) via the. This support shaft (12 ') swings the connecting rod (31) in the conventional device (for example, the one shown in FIG. 4) for connecting the X-ray tube devices (1) and (2) and the film holding part (10). Corresponding to the moving shaft, supporting shaft (1
The axis (Y-Y) of 2 ') connects the focal point (F) of the X-ray tube (1) and the film center (f) of the film holding unit (10) (▲
() Is always crossed at point (0).

The neutral position of this X-ray imaging system, that is, the line segment (▲
In the state shown in FIG. 1 in which ▼) is orthogonal to the celestial body (8), ▲ ▼: ▲ ▼ = the weight of the film holding part (10) (W
₂ ): X-ray tube device (1), (2) own weight (W ₁ ) ...... (a) is almost established, that is, the (0) point, that is, the center of the cutting plane (XX) is at a fixed position. It is set. Therefore, the top plate (8) in FIG.
(8) The predetermined cut surface of the subject placed on the
After matching the cutting plane (XX) passing through (0), turn base plate
When rotating (6) counterclockwise by 90 ° and performing tomography in the standing position of the subject, the X-ray tube devices (1), (2) are set with respect to the swing center (0). The moments acting from the own weight of the film and the film holding part (10) are W ₁・ ▲ ▼, W ₂・ ▲
However, both of these moments can be regarded as having the same magnitude by the formula (a), and the directions are opposite, so that the weight balance around the cutting center (0) is automatically taken. It is supposed to be.

The hollow pillar (12) has a fan gear (25) fixed to the back of the hollow pillar (12) so that the center of the support shaft (12 ') is aligned with the center of the support shaft. Sometimes hollow stanchions
Pinion (26) to swing (12) around swing center (0)
A drive motor (M) fixed to the output shaft is installed inside the frame (7).

Furthermore, the upper strut (4) and the lower strut (11) are substantially diagonally across the axis (Y-Y) passing through the cutting center (0), and the longitudinal direction of the respective strut (4), (11). Racks (13) and (14) having the same module are fixed in parallel with.
In these racks (13) and (14), the rotating shafts (2
Gears (15) and (16) fixed to (0) and (21) are meshed with each other. If the numbers of teeth of the gears (15) and (16) are Z ₁ and Z ₂ , respectively, this tooth number ratio (Z ₁ / Z ₂ ) is the internal division ratio (▲ ▼ / It is set to be almost equal to (▲ ▼). Also the rotary shaft (20),
Pulleys (18) and (19) with equal pitch diameters are fixed to the outer ends of (21).
An endless timing belt (17) is stretched between (18) and (19).

Next, the operation of this device will be described.

In this device, the structure of the holding mechanism consisting of the upper support column (4) of the X-ray tube device (1) and (2), the hollow support column (12), the support shaft (12 '), etc. seems to be a conventional arc moving type. It is one of the characteristic points that it seems to be similar to the one in the above, but is configured to perform the operation substantially in accordance with the parallel movement system. About this operation, the operation process of FIG. 3 is performed. The operation will be described together with the operation explanatory diagram shown.

The X-ray imaging system is moved from the neutral position shown in FIG. 1 to the swinging position where the deflection angle θ is shown in FIG. 3 at the swing position by driving the pinion (26) by the drive motor (M), and the fan gear (25 ) Is rotated by rotating it counterclockwise. During this time, the film holding part (10) is moved along the guide rail (9), the film center (f) moves to (f '), and the focus (F) of the X-ray tube (1) becomes (F'). ).

▲ ▼ = m, ▲ ▼ '= m' = msec θ> m
Therefore, the lower support column (11) is pulled out from the hollow support column (12) by a length of m′−m = Δm. And the pull-out length of this lower column (11) does not exceed the amount of downward movement of the rack (14), so the gear (1
6), that is, detected as the clockwise rotation angle (β) of the rotation axis (21). Then, the clockwise rotation angle (β) of the rotating shaft (21) is directly transmitted to the gear (15) via the pulley (19), the timing belt (17), the pulley (18) and the rotating shaft (20). It In this way, the gear (15) rotates clockwise
By rotating by (β), the rack (13) meshing with the gear (15) is moved upward, and the upper column (4) is pushed out from the hollow column (12) accordingly. Assuming that ▲ ▼ = 1, the swing center (0) is a fixed point as described above, and 1 / m = c (constant). Further, the gear (15) has the number of teeth Z ₁ , the gear (16) has the number of teeth Z ₂ , and the tooth number ratio of the _two is set to Z ₁ / Z ₂ = l / m = C. 13) The amount of upward movement, that is, the upper strut (4)
If the extrusion length of is Δl, then Δl = Δm · c.

By the way, if ▲ '▼ = l', then l '= l + Δl =
l + Δm. c and m ′ = m + Δm. Therefore, l '/ m' = (l + Δm · c) / (m + Δm) = c (m +
Δm) / (m + Δm) = c.

This means that in this device, the focus (F) of the X-ray tube (1)
Means that the operation substantially in accordance with the parallel plane moving method is performed.

In order to perform a tomographic image on a subject in a horizontal position in this apparatus, the top plate (8) is raised by the above-described lifting mechanism, and a predetermined cut surface of the subject is converted into a (XX) cut surface. After matching, the drive motor (M) is driven, and the fan gear (25) is rotated by the pinion (26) so that the deflection angle of the hollow support column (12) with respect to the vertical line is about 25 ° when viewed from the front. Drive motor (M) is stopped. Then, the drive motor (M) is driven again in the opposite direction to the above direction, and when the deflection angle of the hollow support column (12) with respect to the vertical line becomes, for example, about 20 °, the X-ray tube (1) stops the aperture (2). ) Is started to irradiate the subject with X-rays, and when the deflection angle on the side opposite to the above reaches about 20 ° after passing through the vertical line of the hollow column (12), X-ray irradiation is performed. And then the drive motor (M) is stopped. During this time, the focal point (F) of the X-ray tube (1) and the film center (f) of the film holder (10) are horizontally moved in parallel, and tomography according to the parallel plane moving method is performed.

Regarding tomography of the standing subject, as described above, the X-axis is set around the swing center, that is, the cutting center (0).
Since the moments acting from the respective weights of the wire tube devices (1) and (2) and the film holding device (10) are balanced, the shooting can be smoothly performed even if the drive motor (M) does not have a margin. . The weight (W ₁ ) of the X-ray tube devices (1) and (2) is, for example, 90 kg, and the weight (W ₂ ) of the film holder (10) is, for example, 24.
Assuming 0 kg, the above-mentioned l / m = W ₂ / W ₁ = 240
Kg / 90Kg≈2.67, that is, the point where the line segment (▲ ▼) is internally divided by 2.67: may be set as the swing center (0).

Further, the rotary shaft (18) provided on the upper part of the hollow strut (12) is connected to the output shaft of the motor mounted via the bracket fixed to the hollow strut (12) through the shaft coupling, and the pulley (18 )
Is attached to the rotary shaft (20) via a clutch, the rotary shaft (20) that has been connected to the pulley (18) by the clutch is driven by the motor, and the gear (15) drives the rack ( 1
The focus of the X-ray tube (1) is moved by moving (3) upwards or downwards and pushing or pulling only the upper support (4) with respect to the hollow support (12) accordingly.
By changing the position of (F) and making the distance between the focus (F) and the film center (f) so-called FFD variable, the optimum FFD can be set for the subject in normal X-ray photography.
After performing such photographing, the upper column (4) must be returned to the original position and the pulley (18) should be connected to the rotary shaft (20) by the clutch.

[Effect]

The tomographic X-ray apparatus according to the present invention has the following effects.

(i) Since the X-ray tube device is designed to operate in a substantially parallel plane movement system without a guide rail for guiding it, even when the front size of the device is limited, the conventional parallel plane movement is performed. The tomographic image capturing range can be made larger than that of the apparatus of the system, and the blurring does not increase even when the tomographic angle is large as in the apparatus of the arc moving system.

(ii) Even though the mechanism is simple, the X-ray tube apparatus is designed so that the weight balance around the cutting center can be taken without using the balance weight in tomography in a position other than the horizontal position of the subject. The speed control can be smoothly performed, and the tomographic accuracy can be improved.

[Brief description of drawings]

FIG. 1 is an external front view of a tomographic X-ray apparatus which is an embodiment of the present invention, FIG. 2 is an external side view of the same, and FIG. 3 is an operation explanatory view showing an operating process of the apparatus of this embodiment. FIG. 4 is a schematic view of a mechanism according to a conventional parallel plane moving method, and FIG. 5 is a schematic view of a mechanism according to a conventional arc moving method. (1) ... X-ray tube, (2) ... Aperture, (3) ... Support arm, (4) ... Upper column, (5) ... Base, (6) ... Rotating base plate, (7) ... Frame, (8) ... Top plate, (9) ... Guide rail, (10) ... Film holding part, (11) ... Lower support, (12) ... Hollow support, (12 ') ... Support shaft, (13), (14) ) ... Rack, (15), (16) ... Gear, (17) ... Endless timing belt, (18), (19) ... Wheel (pulley), (F) ... Focus of X-ray tube, (f) ... Film Center, (0) ... swing center (cutting center), (XX) ... cut surface, (YY) ... swing axis.

Claims (2)

[Claims] 1. An X-ray tube device (1), (2) and this X-ray tube device.
Upper strut (4) that holds (1) and (2) via support arm (3)
A base (5) fixed to the floor, a rotary base plate (6) rotatably supported by the base (5), and a frame fixed to the rotary base plate (6) (7), a top plate (8) engaged with the frame (7) in a vertically movable manner, and a top plate (8) attached to the frame (7)
A guide rail (9) fixed parallel to the guide rail (9), a film holding portion (10) which is linearly moved by being guided by the guide rail (9), and a lower portion which holds the film holding portion (10) at a lower end portion. A pillar (11), the upper pillar (4) and the lower pillar (11)
Tomographic X-ray radiographing apparatus comprising hollow columns (12) slidably engaged with the respective frames with their longitudinal axes aligned and slidably engaged with the frame (7) In the above, in each of the upper strut (4) and the lower strut (11), the swing center (0) of the hollow strut (12) is sandwiched diagonally and the length of the strut (4), (11) is increased. Rack parallel to the direction (1
3) and (14) are fixed and these racks (13) and (14)
The gears (15) and (16) meshing with the hollow support (1
Rotating shafts rotatably attached to the upper and lower parts of 2)
(20) and (21) are fixed to each other, and the gear ratios of these gears (15) and (16) are set to the above X at the neutral position of the X-ray imaging system.
X-ray tube focus (F) and film holder of the X-ray tube devices (1) and (2)
The internal division ratio (▲ ▼ / ▲) where the line segment (▲ ▼) connecting the film center (f) of (10) is internally divided by the swing center (0).
)), And the rotation shafts (20), (21) are connected to each other via a rotation transmission member so as to rotate by the same rotation angle, a tomographic X-ray apparatus. 2. The swing center (0) of the hollow column (12) is located between the focal point (F) of the X-ray tube and the film center (f) of the film holding section (10) at the neutral position of the X-ray imaging system. Connect the line segment (▲ ▼)
The fault according to claim 1, wherein the X-ray tube devices (1) and (2) and the film holder (10) are internally divided in inverse proportion to their own weights (W ₁ ) and (W ₂ ), respectively. X-ray equipment.