JPS6327700Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a linear motion X-ray tomography apparatus in which an X-ray tube and a film are relatively moved in parallel to photograph a subject.

The linear motion type is the most common and basic type of X-ray tomography equipment, and it allows for a large distance between the X-ray tube focal point and the film, and a small distance between the top plate surface and the film, resulting in less blur. It has the advantage of providing tomographic images. Furthermore, the moving distance of the focal point is shorter than that of other circular or elliptical motion systems, and the imaging time can be reduced to about 1 second, thereby reducing the exposure dose. However, due to its operating principle, the distance between the focal point and the film changes during parallel movement, and as the swing angle of the swinging rod that engages the two with respect to the vertical line increases, the amount of X-rays that reach the film decreases. There is a problem. To prevent this, conventional devices rotate a drive lever of length r, which is engaged via a sliding member with a vertical guide fixed to the X-ray tube via a holding mechanism, at a constant angular velocity ω. It is configured to do so. Therefore, the horizontal movement speed v of the X-ray tube becomes v=rωsinθ,
Here, θ is the angle that the drive lever makes with the vertical line of the swing rod. This adjusts the X-ray dose when the deflection angle is large, that is, when the X-rays are obliquely incident, and also performs soft start and soft stop of the X-ray tube. However, with this drive method, the preliminary running range for the X-ray tube to reach a predetermined speed is long, and the X-ray tube running guide rail is long.
There are drawbacks that the device becomes large and the drive mechanism described above is complicated. This tomographic X-ray imaging device was devised to simplify this and make the device more compact, and the patent application was filed on May 10, 1980. This device, as shown in FIG. X-ray tube 5 engaged with
and the swing center shaft 3 are engaged with each other via a sliding member 6. In the diagram, 7 is X
The ray tube traveling _{guide rail} , ₍ X ₁ + The distance between the drive lever rotation center axis position 4 and the swing rod rotation center axis 3, l is the distance between the guide rail 7 and the swing rod rotation center axis 3, 8 is the top plate, and h is the swing distance from the top plate. The distance from the moving rod rotation center axis position 3 becomes the aiming cross-sectional height of the subject (not shown), and is adjustable within a certain range. 9 is a film butt travel guide, 10 is a film butt, 11 is a support shaft that slidably engages the above-mentioned 10 and the swinging rod 3, and two-dot chain lines 2' and 2'' are swings at the start and end of X-ray exposure. Moving rod 2
, the dashed line 2 is the position of the swinging rod 2 when the X-ray tube 5 is at the stop position, and the angle R between the swinging rod 2 and the drive lever 1 is 90° (radian angle | π/2|). Angle α formed by 2′ and 2″ above
is the photographing angle when the cross-sectional height is h. With the above configuration, if the drive lever 1 rotates, for example, clockwise at a constant angle ω, the guide 7 of the X-ray tube 5
The horizontal movement speed V at the top is V=
r・ω・l(r+asinθ)/(a+fsinθ) ² ,
Here, θ is the rotation angle of the drive lever 1. Figure 2 is a graph showing sinusoidal changes in V, and the horizontal axis is X in Figure 1.
The moving ranges of the wire tubes X ₀₁ , X ₁ , X ₂ , X ₀₂ and the angle R between the drive lever 1 and the swinging rod 2 are shown in radians,
The vertical axis indicates the horizontal movement speed V of the X-ray tube 5. V ₀₁
indicates when the speed V=0 at the start in Figure 1
V ₁ is the velocity V at the start of X-ray exposure, which is 58.6% of the maximum velocity V _nax (approximately
60%). V ₂ is the velocity at the end of X-ray exposure and is also about 60% of V _nax . V ₀₂ has two swinging rods.
In other words, when the position is (R=+π/2) radian angle, the X-ray tube is stopped. As this graph shows, it can be seen that the rate of rise and fall of the speed V in the preliminary travel range of X ₀₁ and X ₀₂ is extremely steep compared to that during X-ray irradiation. The device that drives the horizontal movement of the X-ray tube using the swinging rod 2 shown in Figure 1 as a slide link has a simple structure and has the advantage that the traveling distance of the X-ray tube is shorter than that of the conventional device. However, if the cross-sectional height of h is changed by changing the subject or by changing the aiming cross-section even for the same subject, it will start during the steep speed change in the preliminary travel range of X ₀₁ and X ₀₂ mentioned above, and There is a problem with stopping. FIG. 3 is a diagram for explaining this, and the explanations of the same symbols as in FIG. 1 will be omitted. Now h is
h', the orthogonal intersection _C1 of the drive lever 1 and the swinging rod 2 changes to _C'1 , the starting position 5S of the X-ray tube 5 also changes to 5S', and the rotation of the drive lever 1 changes. The angle θ also increases as θ', and therefore the stop position 5P of the X-ray tube also changes to 5P'. That is, the traveling distance of the X-ray tube (X ₀₁ +X ₁ +X ₂ +X ₀₂ ) also changes as (X ₀₁ ′+X′ ₁ +X′ ₂ −X ₀₂ ′). As the swing center 3 of the swing rod 2 changes in this way, various specifications of the device change, so for example, a limit switch for the rotational drive motor of the drive lever 1 may be provided in the travel guide of the X-ray tube 5. Can not.
The only option is to either stop the drive lever 1 and the swinging rod 2 at right angles so that they come to a natural stop, or adjust the timer each time to stop the drive motor. In any case, due to the mechanical friction of each part of the device, it does not necessarily stop in the perpendicular state of (R = ±π/2), and if R at the time of stopping is (+π/2)
If it were to stop at a smaller angle R', then the X-ray tube 5 and the film buttsky, which have a high velocity of V', for example V'≈0.2V _nax , would suddenly stop at P' of the curve in Figure 2. , a shock is applied. Also, when the drive lever 1 is rotated counterclockwise from R', when the switch is turned on, it starts from V' and gives a shock to the X-ray tube, etc., just like when it is stopped. If this happens repeatedly, it may cause damage to the X-ray tube or shorten its lifespan.

This idea was created in view of the current situation described above, and it simplifies the swinging rod drive mechanism of conventional linear motion X-ray tomography equipment and eliminates the drawbacks of improved equipment that shortens the traveling distance of the X-ray tube. It is. The goal is to eliminate shocks when starting and stopping the X-ray tube, prevent damage to it, and increase its running speed to shorten imaging time, obtain high-quality images, and reduce radiation exposure. This is what we are trying to achieve. That is, the sliding member at the intersection or engagement portion with the swinging rod of the drive lever is set as the rotation center of the axis of a bearing, for example, and is slidably engaged with the swinging rod. A rotary member that rotates according to the cross-section angle is provided at the tip of the drive lever, and a detector is provided to detect the cross-section angle that the rotary member forms with respect to the drive lever. detecting at least a radian angle (±π/2) between the swinging rod and the drive lever without being affected by a change in the vertical line of the rotation center of the swinging rod due to a change in the height of the swinging rod; This invention relates to an X-ray tomography apparatus characterized in that a swinging rod is stopped and started.

Embodiments of this invention will be described below with reference to the drawings. FIG. 4 is a front view showing the configuration of the intersecting and engaging portion of the swinging rod and the drive lever of an embodiment of the device of this invention.
FIG. 5 is a side sectional view thereof, and FIG. 6 is a plan view thereof viewed from the X-ray tube engaging portion. 1T is the tip of the drive lever, 2T is the tip of the swinging rod, and the dashed line 5 is X.
This is the ray tube holding part, and the figure shows the position when the X-ray tube 5 is on the vertical line Y shown in FIG. 1, that is, when the drive lever 1
This shows a state in which the swinging rod 2 and the swinging rod 2 are aligned in a straight line. C is fixed to the drive lever at the axis of the cross-engaging portion between the drive lever 1 and the swinging rod 2. Reference numeral 21 is a bearing that is rotatably supported by the above-mentioned axis C, and slides by fitting into the groove 22 of the swinging rod 2. Reference numeral 23 is a rotary cam plate formed in a fan shape and rotatably supported on the axis C. 24 is a bearing provided at the tip of a bearing shaft 25 installed in the center of the rotating cam plate 23, and like the bearing 21 above, it fits into the concave groove 22 of the swinging rod 2 and can freely slide therewith. engaged. Reference numerals 26 and 27 are micro switches fixed to the drive lever 1T, and when the rotary cam plate comes to the position indicated by the one-dot chain line 23', the operation roller 26S of the micro switch 26 moves to the right edge 23R' of the cam plate. Twisted and pressed micro switch 26
is configured so that it is turned on. This state is the X-ray tube start position shown in FIG. 1, and indicates that the angle (R=-π/2) between the drive lever 1 and the swinging rod 2 has been detected. The ON/OFF operation of this micro switch 26 or the micro switch 27 that detects the angle (R=+π/2) at the time of stop is not shown, but the operation of the drive lever 1 is controlled by a sequence control circuit composed of relays, timers, etc. It controls the reversible rotation of the motor that drives rotation. With this configuration, the intersection angle R between the swinging rod 2 and the drive lever 1 always stops at (±π/2) radian angle no matter how the cross-sectional height h of the aiming cross is changed, and starts at that angle. I will do it. This is because soft start and soft stop are always performed at the zero speed position at V ₀₁ and V ₀₂ shown in Figure 2.
It does not give a shock to wire tubes, etc.

The above is an explanation of the embodiment of the device of this invention.
This invention is not limited to the illustrations and explanations; for example, the positions of the rotating cam plate and the detector in FIG. 4 may be reversed, and the shapes and types of the rotating cam plate and the detector are also limited to those shown in the illustration. In addition to mechanical microswitches, there are many other possible detectors, such as magnetic proximity switches or optical elements. It is sufficient if the rotation can be detected and the drive source can be accurately controlled. Furthermore, if a plurality of angle detectors or a continuous angle detector such as a potentiometer is attached to a rotating member, it is not enough to simply detect an orthogonal angle of (π/2), as shown in FIG. The rotational speed of the drive motor in driving range X ₀₂ can be freely controlled. The solid line curve V _t in FIG. 7 is a change characteristic of the horizontal movement speed V of the X-ray tube 5 due to the constant angular velocity ω of the drive lever 1 explained in FIG. On the other hand, 1
The dashed dotted line V _t ' increases the preliminary traveling speed by continuously changing the angular velocity ω of the drive lever 1 using a detector such as the potentiometer, and the stopping point, that is, the intersection of (+π/2) The speed is gradually converged as the angle approaches, and the speed is stably and accurately stopped at the orthogonal angle.

This idea is structured as above, so
This eliminates the drawbacks and problems of conventional horizontal motion X-ray tomography devices. In other words, even though the center of oscillation of the oscillation rod that horizontally moves the X-ray tube and the film stick relative to each other changes depending on the arbitrary setting of the aiming cross-sectional height of the object, it is possible to start and stop the oscillation. This can always be done without impact. With this function, the horizontal movement of the X-ray tube can be made faster and imaging can be performed in a shorter period of time.
Furthermore, in the case of chest tomography, for example, several photographs can be taken during one breath, thereby providing a convenient device that can improve diagnostic performance.

[Brief explanation of the drawing]

Figure 1 is a diagram illustrating the operating principle of a device (apparatus to which this invention is applied) devised in which a swinging rod is used as a slide link in a horizontal motion X-ray tomography device and is swung by a drive lever. is a graph showing the horizontal movement speed characteristic curve of the X-ray tube of the above device; FIG. 3 is a diagram illustrating the operating state of each mechanism as the aiming cross-sectional height changes in the device of FIG. 1;
Fig. 4 is a front view of the intersection angle detection mechanism of the swinging rod and drive lever as an embodiment of this invention, Fig. 5 is a side sectional view taken along the line -' in Fig. 4 above, and Fig. 6 is the same. FIG. 7 is a plan view of the above-mentioned mechanism as seen from the X-ray tube side, and is a characteristic diagram of the X-ray tube moving speed when the angular velocity of the drive lever is controlled as another embodiment of this invention. 1... Drive lever, 2... Rocking rod, 3... Rotation center of the above 3 (corresponding to one point on the aiming cross section of the subject), 4... Rotation center (axis) of the drive lever of the above 1 , 5... X-ray tube, 6... Sliding member that engages the swinging rod 2 and the drive lever 1 and slides on the swinging rod 2, 7... Horizontal movement guide rail for the X-ray tube,
8...Top plate on which the subject is placed, h...Height of cross section from top plate 8, 10...Film storage section, ω...
...Rotational angular velocity of the drive lever 1, C...Axis of the intersection or engagement portion between the drive lever 1 and the swinging rod 2, 21...Sliding member (bearing) of the intersection or engagement portion, 22...
...concave groove in the axial direction of the swinging rod, 23...rotating member (rotary cam plate) that rotates at the intersection angle of the swinging rod 2 and drive lever 1, 24... provided on the rotating member 23 and swinging A bearing that slides in the concave groove of the rod 2, 26,
27... Detector for detecting the crossing angle formed with the drive lever of the rotating member, R... Rocking rod 2
and drive lever 1 at starting and stopping angles (±π/2 radian angle).

Claims (1)

[Scope of utility model registration request] An X-ray tube 5 and a film 10 are engaged at both ends thereof, and a sliding member 6 or 21 is connected between the X-ray tube and the film of the swinging rod 2 whose rotation center is a point 3 on the aiming cross section of the object. A drive lever 1 is provided with a drive lever 1 that is cross-engaged through the drive lever and has a rotation center 4 vertically above the axis of rotation of the swing rod, and the swing rod is swung by rotation of the drive lever; In the apparatus for photographing a subject while relatively moving the X-ray tube and the film in parallel, the axis C of the sliding member 21 at the cross-engaging portion of the drive lever with the swinging rod is the center of rotation, and The swinging rod and member 24
A rotating member 2 that is slidably engaged with the swinging rod and rotates according to the intersection angle R between the swinging rod and the drive lever.
3 is provided at the tip of the drive lever, and detectors 26 and 27 are provided for detecting the intersecting angle formed by this rotating member with respect to the drive lever, and the height of the cross-section of the object to be photographed above the top plate is provided. At least a radian angle (±π/2) between the swinging rod and the drive lever is detected regardless of a change in the rotation center of the swinging rod on the vertical line due to a change in h, and the swinging rod is rotated at this angle. An X-ray tomography apparatus characterized in that the swinging stops and starts.