JPS62172288A - Scanning apparatus for positron emission ct - Google Patents

Abstract

PURPOSE:To smoothly and parallelly move a scanning apparatus with high stop position accuracy, by a simple constitution such that a ring detector support is moved in a linear motion converted from rotary motion through a linear guide mechanism and the stop of rotary motion is controlled through a cam. CONSTITUTION:When the shaft member 6 supported by a support leg 4 is revolved by an electromotor 9 with a speed reducer, rotary motion is converted to linear motion by a member 5 relatively moving to an up-and-down direction along with a ring detector support by a linear motion guide 3 coupled with the member 6 by a crank and the linear motion guide 2. A plurality of ring detectors 23 and the support equipped with a collimator between said detectors are moved to the axial direction of the detectors and stopped at a required scanning end position through a cam 11 integrally revolving along with the shaft member 6 and a switch 12. By this method, a CT scanning apparatus is smoothly moved parallelly without moving a patient by a simple constitution and stop-position accuracy can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to a scanning device for positron emission CT.

[Background of the invention]

Many conventional positron emission CT systems use multiple ring detectors (
At the same time as using a radiation detector ring), in order to prevent interference between each ring detector,
A metal with a high linear absorption coefficient is used as a collimator, and this collimator is placed between each ring detector, which is the radiation introduction path, to measure multiple tomographic planes. However, in this case, since the collimator is thick, even if simultaneous measurements are made with the opposing detectors of each of the 6 ring detectors, 11 and even if simultaneous measurements are made with the adjacent ring detectors,
1/ of this distance from the center of the distance between each ring detector
Area 4 can hardly be measured. Conventionally, the method of measuring this area by moving the subject was generally used, but this method uses positron emission CT to induce mental agitation in the subject and to observe physiological changes within the subject. However, there was a drawback in that the effect appeared on the measurement data and hindered accurate diagnosis.

Therefore, in order to improve this drawback, instead of moving the subject, multiple ring detectors and collimators are moved in the direction of their central axis, and the distance between each ring detector is equal to 1.
A method of measuring by moving parallel to /4 is used,
Mechanically, it is quite difficult to move the entire scanning device, which has a considerable weight, with high stopping position accuracy.

[Purpose of the invention]

An object of the present invention is to provide a positron emission CT system in which a plurality of collimators and a plurality of ring detectors can be moved in parallel in the direction of their respective central axes using a simple mechanism and with high stopping position accuracy. The present invention provides a scanning device.

[Summary of the invention]

A feature of the present invention is that when a plurality of ring detectors and collimators are moved in parallel in the direction of their central axes, this movement supports the plurality of ring detectors and collimators movably with respect to the support legs, and this drive is This can be easily achieved with a mechanism that converts the rotational motion of the drive source into linear motion using an eccentric cam whose rotational diameter is equal to the parallel movement plane and two linear guide grooves.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 2 is a schematic diagram showing a partial cross section of a plurality of ring detectors 23 and a collimator 22 arranged on a concentric axis of the Bontron emission CT apparatus in this embodiment. Each ring detector 23 is composed of a circular arrangement of detectors for detecting gamma rays, and each of these detectors is configured by pairing, for example, a photomultiplier tube 20 and a solid scintillator 21, and They are arranged in a ring shape in one plane, facing the center of the circle. Further, each collimator 22 is made of a material having a high absorption coefficient of gamma rays, such as lead or tungsten, and is arranged between each ring detector 23 so as to prevent interference between adjacent ring detectors 23.

FIG. 1 is a perspective view of the scanning device for positron emission CT in this embodiment, with only the right side shown for the sake of simplicity. Although only one ring detector is depicted in FIG. 1, a plurality of ring detectors 23 and collimators 22 arranged in parallel are provided as in FIG. 2.

These ring detector 23 and collimator 22 are
In order to smooth the counting frequency and increase the density at the position of the coincidence line of the r-ray pair, the S/G detector 2
3″f: Supported by a ring detector support mechanism and a moving mechanism (not shown) that perform rocking motion within the plane (FIG. 1 X-Y plane view).Furthermore, these ring detector support mechanisms and The moving mechanism is parallel to the central axis of the ring detector 23 and has a set of parallel side edges la.
It is built into the ring detector support 1 which has a In addition, these ring detector 23 and collimator 22
A linear motion guide 2 is provided on each side edge 1a so that the S/G detector support 1 can freely move linearly in order to move parallel to its central axis direction, that is, in the Z-axis direction in FIG. , the ring detector support 1 is attached to the support leg 4 via this linear movement guide 2.

Further, this ring detector support 1 is provided with a member 5 via a linear movement guide 3 so as to be linearly movable in a direction perpendicular to the direction of movement relative to the support legs 4, that is, in the Y-axis direction. That is, the member 5 is supported so as to be freely movable within one plane with respect to the support leg 4. Also,
A shaft member 6, which is eccentric between the member 5 and the support leg 4, is attached to the member 5 and the support leg 4 so as to be freely rotatable via a bracket 7 and a bearing 8. The member 6 is connected to an electric motor 9 with a reduction gear.

Further, a cam 11, for example, is attached to this shaft member 6 so as to be rotated by an electric motor 9 with a reduction gear, and a switch 12 is activated as the cam turns 1/2, and a control device (not shown) is activated. Electric motor with reducer 9
The rotation start and stop are controlled in 1/2 rotation increments. In the scanning device of the positron emission CT apparatus described above, the left part (not shown) is equipped with the same mechanism as the right part.

In the scanning device of the positron emission CT apparatus having the above mechanism, the shaft member 6 is
When the shaft member 6 is rotated, since the tip of the shaft member 6 is eccentric, it traces a circular locus with the radius of this eccentricity. As a result, the member 5 moves while drawing this circular locus with respect to the support leg 4, so that the ring detector support 1
moves linearly in the Z-axis direction with respect to the support leg 4 at a distance twice the eccentricity of the shaft member 6 and with a speed varying sinusoidally. Therefore, if twice the amount of eccentricity of the shaft member 6 is set as 1/4 of the distance between each ring detector, and the shaft member 6i is rotated by 1/2, linear movement will be made at 1/4 the distance between each ring detector. In other words, by placing a switch activated by a cam at an appropriate position and controlling the electric motor 9 with a reduction gear so that the shaft member 6 rotates 1/2, the fault plane that could not be measured by the collimator can be covered. Measurements can be made by moving the device without moving the sample. Furthermore, since the moving speed of the ring detector support 1 changes sinusoidally, vibrations due to the inertia of the device that occur when starting and stopping linear motion can be suppressed. In this embodiment, the left part (not shown) is also provided with the same mechanism as the right part, and the electric motor with a reduction gear on the left part is driven simultaneously with the electric motor with a reduction gear 9 on the right part, and the above-mentioned Although the movement of the ring detector support 1 is performed, a one-sided drive system may be used as long as a precise guide mechanism with no play is used.

〔Effect of the invention〕

According to the present invention, the collimator and ring detector can be moved smoothly and with high stopping accuracy, and even tomographic planes that could not be measured can be measured without causing mental agitation to the patient, making it possible to obtain accurate and large amounts of image information. This allows for more accurate diagnosis during clinical testing.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a scanning device for positron emission CT according to an embodiment of the present invention, and FIG. 2 is a partial cross-sectional schematic diagram showing a plurality of ring detectors and collimators in the embodiment. DESCRIPTION OF SYMBOLS 1... Ring detector support body, 2... Linear motion guide, 3... Linear motion guide, 4... Support leg, 5...
... member, 6... shaft member, 7... bearing, 8... bearing, 9... electric motor with reduction gear, 22... collimator,
23...Ring detector.

Claims (1)

[Claims] 1. A scanning device for positron emission CT, which has a ring detector formed by arranging detectors arranged in an annular shape in parallel in one plane, and a collimator arranged between each ring detector. , a support body that supports the ring detector and the collimator, support legs that support the support body via a guide mechanism on both sides thereof, and reciprocating movement of the support body a predetermined distance in the direction of the center axis of the ring detector. What is claimed is: 1. A scanning device for positron emission CT, comprising: a driving source for moving the object; and a moving mechanism comprising an eccentric cam attached to the driving source.