JPS6323057Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a light beam device for a CT scanner, and more specifically, to a light beam device for a CT scanner whose gantry can be tilted.

[Conventional technology]

CT scanners with a tiltable gantry are equipped with a light beam device to set the slice plane.

The light beam device includes a light projector that emits a light beam associated with Fanbeam X-rays. The projector is attached to a base that supports the gantry so as to be rotatable about an axis parallel to the gantry's tilt axis, and by rotating in synchronization with the rotation of the gantry, the projector emits light from the projector to the subject. The light stripe formed by the light is rotated by an angle corresponding to the tilt angle of the gantry.

[Problem that the invention attempts to solve]

In recent years, in CT imaging, imaging of slice planes parallel to the body surface, that is, coronal scan, has been widely used, but determining the slice plane takes a lot of time. For normal imaging, the slice plane can be set by aligning the light beam from the projector with the OM line and then rotating the gantry until the light beam is positioned at the desired slice plane. However, in the coronal scan, OM
The angle between the line and the slice plane becomes extremely large, and the gantry cannot be tilted beyond this angle, so the subject's posture is changed and the gantry is tilted again, sometimes repeating this process many times. At present, it is necessary to determine the slice plane depending on the situation.

This invention has a tiltable angle of the gantry.
To provide a light beam device for a CT scanner that can easily and quickly set a slice plane even if the angle is smaller than the angle between the OM line and the slice position.

[Means for solving problems]

The light beam device for CT scanner of this invention is
a first rotatable member, a first rotatable member, and a first rotatable member disposed coaxially with the first rotatable member; a second rotating member, a stationary member coaxially arranged with these rotating members, means for causing the gantry to rotate by a difference between a rotation angle of the first rotation member and a rotation angle of the gantry; means for rotating the projector in accordance with the rotation of the rotating member; the first rotating member has a rotational position at an angle of 0°, and angle scales are provided in both rotational directions with the rotational position as the center, and the second rotating member is an indicator. The stationary member is characterized in that each stationary member is provided with an angular scale from 0° to the maximum tilt angle of the gantry.

[Effect]

The light beam device of the present invention rotates the first rotating member and aligns the light beam from the projector with the reference position.
When aligned with the line, the angle corresponding to the index on the second rotating member on the angle scale of the first rotating member represents the angle from the vertical line to the OM line, and the angle on the angle scale on the stationary member of the first rotating member represents the angle from the vertical line to the OM line. The angle corresponding to the maximum value represents the angular range in which the gantry can be rotated, that is, the angular position of the slice plane that can be selected, so the gantry tilt angle is OM
Even if the angle between the line and the slice position is smaller, the position of the slice plane that can be imaged relative to the OM line can be immediately known from these rotating and stationary members.

Embodiments of the light beam device of the present invention will be described below with reference to the accompanying drawings.

〔Example〕

In FIG. 1, reference numeral 4 indicates a gantry;
Each indicates the base that supports the gantry.

The gantry 4 includes a rotary plate 3 inside a casing shown in the drawings. The rotary plate 3 has the form of a disc with a through hole in the center, and is arranged so that the through hole coincides with the opening in the casing, and its peripheral surface is connected to the main body which is also housed in the gantry 4. It is supported by rollers located at The X-ray source 1 is equipped with an X-ray tube and an X-ray flux constrictor and is capable of emitting fan beam X-rays. The X-ray detector 2 is of a so-called multi-channel type having a large number of detection elements arranged along the direction of spread of the fan beam X-ray. These are disposed on the rotary plate 3 facing each other with the central axis of rotation sandwiched therebetween.

A shaft 6 extending from the main body of the gantry 4 is held by a bearing on a base 5, so that the gantry 4 can be tilted, for example, at an angle of ±20° with respect to a vertical line. The mechanism for tilting is a well-known mechanism, for example, a chain is arranged along the rotation direction on the bottom of the gantry, both ends of the chain are fixed to the gantry, and a sprocket wheel is engaged with the chain. This is done by rotating a sprocket wheel using an electric motor on a base to move the chain.

In the light beam device, a projector is housed inside an arm 7 extending from a base 5, and is capable of projecting a light beam 8 having a spread related to the fan beam X-rays emitted from the X-ray source 1. I am forced to.

FIG. 5 shows details of the light beam device. The main shaft 21 is arranged between two support plates fixed to the arm 7, and both ends are held by bearings on the support plates. Rotating members 11, 1 are attached to the main shaft.
2 and a stationary member 13 are attached. The rotating member 11 is attached to the main shaft 21 so as to be able to rotate freely, and the rotating member 12 is attached to the main shaft 21 so as to be able to rotate freely.
The stationary member 13 is fixed to the main shaft 21, but is coupled to the arm 7 and prevented from rotating.

The projector 20 includes a light source 26, lenses 27 and 30, and slit plates 28 and 29, and the light beam from the light source 26 is directed through the slit 2 by the lens 27.
8 and 29, and can be projected as a light beam 8 by a lens 30. This projector is arranged on the arm 7 parallel to the tilt center axis of the gantry 4, and when the light beam 8 is projected onto the subject, it emits a narrow and elongated band of light.
In other words, it is possible to project light stripes.

Among the elements constituting the projector, the light source 26, lens 27, and slit plate 28 are attached to one casing, and the slit plate 29 and lens 30 are attached to one casing.
is fixed to arm 7. The casing is rotatably held on the arm 7 by rollers or the like. A gear 25 is provided on the casing, and a gear 22 that meshes with this gear is provided at one end of the main shaft 21, so that the casing can be rotated by rotating the main shaft 21.

A potentiometer 31 is located at the opposite end of the main shaft 21.
is located. This potentiometer is adapted to connect the rotor to the main shaft 21 and to generate an electrical signal related to the rotation angle of the main shaft 21. The potentiometer 31 and another potentiometer 32 are electrically connected to a comparator circuit 33, and the comparator circuit is electrically connected to a drive circuit 34 of a motor 35 that causes the gantry 4 to rotate. Note that the rotor of the potentiometer 32 is connected to the rotation center shaft 6 of the gantry 4, and is capable of generating a signal related to the tilt angle of the gantry 4.

In this light beam device, when the rotating member 11 is rotated, the casing gear 22 and the gear 25
The light source 26, the condensing lens 27, and the slit plate 28 are rotated, and the light stripe on the subject can be rotated by an angle related to the rotation angle of the main axis 21. Further, when the rotating member 12 is rotated, the potentiometer 31 is rotated, and the potentiometer 31 is rotated by the rotating member 1.
This output signal is inputted to a comparator circuit 33 together with the signal voltage of the potentiometer 32, and the comparator circuit 33 compares the current tilt angle of the gantry 4 with the set angle of the member 12. A signal related to these differences is output to the drive circuit 34, and the drive circuit 34 operates the motor 35 that rotates the gantry 11, causing the gantry 4 to rotate by an angle related to the rotation angle of the rotating member 12. can be made to

FIG. 2 shows rotating members 11, 12 and stationary member 1.
3 details are shown. These members are composed of disks having the same radius, and are arranged so that a portion thereof protrudes from the opening of the operation panel 9 on the circumferential surface. An angle scale 14 is provided on the circumferential surface of the rotating member 11 in positive and negative directions with one rotational direction as a positive direction and the opposite rotational direction as a negative direction, with an angle of 0° as the center. Further, an index 15 is provided on the circumferential surface of the rotating member 12.
An angle scale 16 is also provided on the circumferential surface of the stationary member 13 in the plus and minus directions with an angle of 0° as the center. There is.

In this light beam device, the subject is placed on the top plate of the bed device so that the body axis coincides with the central axis of rotation of the rotary plate 3, and the projector 20 is moved by the movement of the top plate.
, the light beam 8 can project a light stripe onto the subject. This light stripe is in a vertical position when the zero value on the angular scale 14 of the rotating member 11 corresponds to the zero value on the angular scale 16 on the stationary member 13, and the gantry 4 is in a vertical position when the index 15 of the rotating member 12 is stationary. When the angle scale 16 of the member 13 corresponds to the value zero, it is in the vertical state. In this state, when the rotating member 11 is rotated, the projector 20
When the rotation member 12 is rotated, the light stripe can be rotated, and the rotation member 12 is rotated.
The gantry 4 is tilted, the floodlight 20 is rotated at the same time, and the light stripe can also be rotated.

The slice position is set by first rotating the rotating member 11 and aligning the light stripe with the OM line connecting the eyes and ears. At this time, the angle that coincides with the index 15 of the rotating member 12 on the scale 14 of the rotating member 11 is OM from the vertical line.
The angle corresponding to the maximum tilt angle of the angle scale 16 on the stationary member 16 of the rotating member 11 represents the angular range in which the gantry 4 can be rotated. To explain specifically, for example, as shown in Figure 2,
Assuming that the light stripe coincides with the OM line when the rotating member 11 is rotated by an angle of −10°, the angle with respect to the maximum tilt angle of the stationary member 13 at the angle scale 14 of the rotating member 11, that is, the angle +10~ The range of 30 degrees represents the angle that can be projected by tilting the gantry 4. Once the position of the slice plane with respect to the OM line is determined from the angle scales 14 and 16, the rotating member 12 is rotated to align the index 15 with the angle corresponding to the angle of the selected slice plane on the angle scale 14 of the rotating member 11. Therefore, the gantry 4 can be tilted to a desired slicing position.

FIG. 3 shows these angular relationships. Angle θa is the maximum tilt angle of the gantry, θb is the angle from the OM line to the slice plane S to be photographed, and it is determined whether the slice plane S is within the maximum tilt angle θa of the gantry 4.
The angle scale 14 of the rotating member 11, the indicator 15 of the rotating member 12, and the angle scale 1 of the stationary member 13
6, and if this is within the maximum tilt angle of the gantry, the angle corresponding to the index 15 of the rotating member 12 on the angle scale 14 of the rotating member 11 is the angle between the selected slice plane S and the vertical line. Therefore, the gantry 4 can be tilted to the required angle by rotating the rotary member 12 until the index 15 indicates an angle of −10° on the angle scale 15 of the stationary member 13.

Fig. 4 shows the selection state of slice planes in coronal scan, and the slice plane S to be photographed is away from the OM line by an angle θb.
The angle of the OM line with respect to the vertical line varies from patient to patient and depending on the patient's setting.
Since the gantry 4 can only tilt by an angle θa, when the slice plane S is not within the maximum tilt angle of the gantry 4, it is necessary to change the setting for the subject. However, in this light beam device, the rotating member 11 is rotated,
When the light stripe is aligned with the OM line,
The maximum angle scale of the stationary member 13, that is, the value on the angle scale 14 of the rotating member 11 corresponding to the maximum inclination angle θa of the gantry 4 represents the angular range in which the slice plane can be set. It is possible to know from the rotating members 11 and 13 whether the rotation can be made with the rotating member set to represents the angle between the selected slice plane S and the vertical line, so by rotating the rotating member 12 until the index 15 coincides with the same angle on the angle scale of the rotating member 13, the gantry 4 is rotated. It can be tilted to the desired angle. Further, when the slice plane to be photographed exceeds the angle scales 14 and 16, the setting of the subject is changed by the difference between the angle of the slice plane to be photographed and the maximum tilt angle on the angle scale 16, By rotating the rotating member 12 until the index 15 coincides with the same angle on the angle scale of the rotating member 13, the determined slice plane can be photographed.

[Effect of idea]

As described above, the light beam device of the present invention can immediately determine the position of the slice surface that can be imaged from the rotating and stationary members, so the tilt angle of the gantry can be adjusted to match the OM line, as in coronal scanning. Even if the angle is smaller than the angle formed with the slicing surface, the slicing surface can be set quickly and easily.

[Brief explanation of drawings]

The drawings show an embodiment of the light beam device of the present invention, and FIG. 1 is a perspective view of a CT scanner incorporating this light beam device, and FIG.
3 and 4 are explanatory diagrams showing the state of use, and FIG. 5 is a perspective view showing the configuration of the entire device. 4... Gantry, 6... Gantry rotation axis, 8... Light beam, 11... First rotating member,
12... Second rotating member, 13... Stationary member, 1
4...Angle scale of the first rotating member, 15...Indicator, 16...Angle scale of the second rotating member, 20...
...Light projector, 21, 22, 25...Means for rotating the projector, 31-35...Control means.

Claims (1)

[Scope of utility model registration request] A light beam device for a CT scanner capable of tilting a gantry, the emitter being rotatable about an axis parallel to a central tilt axis of the gantry and emitting a light beam associated with a Fan beam X-ray; a second rotating member coaxially arranged with the first rotating member; a stationary member coaxially arranged with these rotating members; a rotation angle of the first rotating member; and a rotation angle of the gantry. and control means for rotating the projector in accordance with the rotation of the second rotating member, with the rotation position of the first rotating member being set at an angle of 0°, and the center of the rotation position being set at an angle of 0°. A CT scanner characterized in that the second rotating member is provided with an angle scale in both rotational directions, the second rotating member is provided with an index, and the stationary member is provided with an angle scale from an angle of 0° to the maximum tilt angle of the gantry. Light beam device for use.