JP3310080B2 - Emission CT device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emission CT apparatus for creating an RI distribution image (RI distribution tomographic image) on a slice plane in a subject.

[0002]

2. Description of the Related Art An emission CT apparatus (hereinafter, referred to as ECT) rotates a detector for detecting radiation (γ-rays) around a subject (hereinafter, also referred to as a SPECT rotation) while moving the detector inside the subject. Radiation emitted from the administered RI (radio isotope) is detected by the detector, and a tomographic image (also referred to as an ECT image) is reconstructed based on the obtained radiation data.

[0003] In ECT, a light projector for projecting linear light, which is a reference line for imaging, onto the object is used for positioning the object at the time of imaging. Conventionally, this projector includes (1) a device that adjusts the median line of the subject to the rotation center of the detector and the effective field of view of the detector (median beam projector);
(2) In some cases, the body axis of the subject is adjusted to the center of rotation of the detector when the bed on which the subject is placed is moved up and down (side projector). The midline projector and side projector are used for positioning the subject before imaging, and project a horizontal or vertical light beam (hereinafter, referred to as a line) or a cross-shaped line combining the both onto the subject. Is what you do.

On the other hand, as the performance of the apparatus has been improved in recent years, the number of cases in which a tomographic image of a head is photographed for the purpose of, for example, examining a cerebrovascular disorder is increasing. At this time, it is necessary to refer to a line (hereinafter, referred to as an OM line) connecting the eye and the ear canal of the human body.

Conventionally, a tomographic image along the OM line is:
It was obtained by changing the body position of the subject. But,
In recent years, to ensure ease of tomographic image reconstruction and quantitativeness,
The actual position of the OM line of the subject is detected by the rotary projector.

[0006] The rotary OM projector emits, for example, a horizontal line parallel to the detector rotation axis, a vertical line orthogonal to the horizontal line, an intersection of the horizontal line and the vertical line, and along a horizontal line with respect to the vertical line. Angle (hereinafter O
An OM setting line having a variable M tilt angle is projected onto the subject. It also has the function of reading the OM tilt angle.

[0007] This rotary OM projector is used as follows. That is, when the subject lies in a normal supine position, the OM line is normally inclined in the body axis direction with respect to the detector rotation axis. Match to OM line. Then, the angle (position data of the OM line) of the OM setting line with respect to the vertical line is read and used at the time of tomographic image reconstruction to obtain a tomographic image of the subject along the OM line.

[0008] By the way, such floodlights such as the midline floodlight, the side floodlight, and the rotary floodlight have conventionally been all fixedly mounted on a non-rotating portion of a gantry, a wall or a ceiling of an inspection room. For example, ECT using a side projector is shown in FIG.
In this ECT, an arm 31 supporting a detector 30 is arranged as shown in FIG.
By rotating around the y-axis in 2, the detector rotates SPECT around an object (not shown) whose body axis is aligned with the y-axis. At this time, the side projector 32 is provided with a gantry 33 that rotatably supports the arm 31.
Is fixed at a required position near the opening 33a along the x-axis.

[0009]

SUMMARY OF THE INVENTION A rotary OM projector is
Since the OM setting line is fixed to the non-rotating part of the gantry, the wall of the inspection room, the ceiling, or the like, the rotation direction of the OM setting line is limited in advance. That is, the position of the OM setting line can be adjusted only with respect to the OM line that is inclined in the body axis direction with respect to the detector rotation axis.

Therefore, if the subject has a disease in, for example, the spine or neck, and the head is rotated around the body axis by, for example, α °, the OM line is shifted as shown in FIG. Therefore, the OM line could not be matched.

In addition, even when the rotary OM projector is not used, it may be impossible to take a posture in which the head of the subject is orthogonal to the rotation center axis. Difficult cases occurred.

When the OM lines cannot be aligned as described above, it is difficult to obtain a tomographic image along the OM lines, and this has been a major problem from the viewpoint of securing quantitativeness of the diagnostic results.

The present invention has been made in view of the above-mentioned circumstances, and a reference line setting means is provided at a position which does not hinder the detection of radiation, and an imaging reference line by the reference line setting means is provided around the body axis. By having a means to rotate to
It is an object of the present invention to provide an emission CT apparatus capable of aligning an OM line rotated around a body axis and easily obtaining a tomographic image along the OM line.

[0014]

To achieve the above object, an emission CT apparatus according to the first aspect of the present invention includes a detector for detecting radiation emitted from a subject into which RI has been injected, and a detector for detecting the radiation. A reference line setting unit that is provided at a position avoiding a detection path of radiation detected by a detector, and sets a reference line for imaging on the subject, and sets the reference line around a body axis of the subject. Reference line rotating means for rotating the reference line, rotation angle detecting means for detecting the rotation angle of the reference line rotated by the reference line rotating means, radiation data detected by the detector and the rotation angle detecting means An image reconstruction device that reconstructs a tomographic image of the subject corresponding to the reference line based on the detected rotation angle.

According to a second aspect of the present invention, there is provided an emission CT apparatus, comprising: a detector for detecting radiation radiated from a subject into which RI is injected; and a detector for detecting radiation around the body axis of the subject. A detector rotation device that rotates the detector rotation device, and a reference line that is attached to a position avoiding a detection path of radiation detected by the detector in the detector rotation device, and that sets a reference line for imaging on the subject. Setting means, reference line rotating means for rotating the reference line around the body axis of the subject, rotation angle detecting means for detecting the rotation angle of the reference line rotated by the reference line rotating means,
An image reconstruction device configured to reconstruct a tomographic image of the subject corresponding to the reference line based on radiation data detected by the detector and a rotation angle detected by the rotation angle detection unit. .

Further, the emission CT apparatus according to the third and fourth aspects of the present invention is a detector for detecting radiation emitted from a subject into which RI has been injected, and a reference line for imaging on the subject. Reference line setting means for setting the reference line, first reference line rotating means for rotating the reference line around the body axis of the subject, and rotating the reference line along a plane parallel to the body axis of the subject Second reference line rotating means for causing, a first rotation angle detecting means for detecting a rotation angle of the first reference line rotating means accompanying rotation of the reference line around the body axis, and The second with rotation along a plane parallel to the body axis
Second rotation angle detection means for detecting the rotation angle of the reference line rotation means, data of radiation detected by the detector, and respective rotation angles detected by the first and second rotation angle detection means. And an image reconstruction device for reconstructing a tomographic image of the subject corresponding to the reference line based on

In particular, an emission CT apparatus according to a fourth aspect of the present invention includes a detector rotating device for rotating the detector around a body axis of the subject, and the first reference line rotating means includes: , Attached to the detector rotating device.

[0018]

According to the emission CT apparatus of the first and second aspects of the present invention, an image is taken by a reference line setting means, for example, a projector for projecting linear light onto the object. (Hereinafter simply referred to as a photographing reference line), and the photographing position is determined. The detector is rotated around the body axis of the subject by the detector rotating device, and radiation from the subject is detected. In this detection, the reference line setting means such as a light projector does not interfere. At the time of positioning, if the subject has been rotated around the body axis, for example, α °,
The photographing reference line is rotated by α ° in the same direction by the reference line rotating means so as to cancel the rotation. Then, the rotation angle of the rotated imaging reference line is detected by the rotation angle detection means. Therefore, the image reconstruction device can reconstruct a slice image corresponding to the imaging reference line rotated by α ° from the rotation angle and the radiation data detected by the detector.

In particular, according to the emission CT apparatus of the second aspect of the present invention, by mounting the projector as the reference line setting means at a required position of the detector rotating apparatus, the detector rotating apparatus can connect the reference line rotating means. It becomes the structure which also serves. Thus, when the operator rotates the detector rotation device by α °, the light emitter also automatically rotates by the same angle, and the photographing reference line can be rotated by α °.

When the imaging reference line is aligned with the OM line of the subject, the OM line is not orthogonal to the rotation axis of the detector but slightly inclined along the sagittal plane, and the inclination angle is β), and The subject is often rotated around the body axis by, for example, α °.

In this case, according to the third and fourth aspects of the present invention, the operator rotates the photographing reference line by α ° by the first reference line rotating means, and further performs the photographing by the second reference line rotating means. The reference line is rotated by a tilt angle β ° in a direction along the sagittal plane. As a result, the shooting reference line
It is aligned with the M line. In this manner, the positioning is reliably performed in response to the rotation of the OM line around the body axis direction and the rotation in the plane direction along the body axis direction.

In this state, the rotation angle α of the photographing reference line rotated by the first reference line rotating means is detected by the first rotation angle detecting means, and the rotation angle α of the photographing reference line rotated by the second reference line rotating means is detected. The rotation angle β is detected by the second rotation angle detection means. For this reason, the image reconstruction device generates a slice image corresponding to the imaging reference line rotated by α ° and β °, that is, the slice image corresponding to the OM line, from the detected rotation angles (α, β) and the radiation data detected by the detector. Can be reconfigured.

In particular, by mounting the projector as the reference line setting means at a required position of the detector rotating device, the first reference line rotating means also serves as the detector rotating device. Thus, for example, when the operator rotates the detector rotation device by α °, the light projector automatically rotates by the same angle, and the photographing reference line can be rotated by α °.

[0024]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a side view of an ECT (also referred to as a scintillation camera) according to the present embodiment, and FIG. 2 is a front view of the ECT.

The ECT 1 includes a gantry 3 having a detector 2 for detecting γ-rays, and a bed 4 which is a support device for placing the subject H thereon.

The gantry 3 includes an arm 5 for supporting the detector 2.
And an arm supporting portion 6 for supporting the arm 5. The arm support 6 is rotatably attached to the gantry 3. In addition, the gantry 3 includes a rotation driving unit 7 that rotates the arm support unit 6 around the body axis of the subject H, and an angle sensor 8 that detects a rotation angle of the arm support unit 6.

Further, the gantry 3 is provided with a projector 9a for projecting an imaging reference line toward the subject H placed on the table 4a of the bed 4. The light projector 9a is provided near the detector 2 of the arm 5, and as shown in FIG. 3, a horizontal light beam e-e ', a vertical light beam g-g', and O
An M-line input setting line ff ′ is projected. Of these projection lines, the OM line input setting line ff ′ is moved along the sagittal surface of the subject (θ in FIG. 2) by operating the projector rotation tool 9b provided in connection with the projector 9a.
Direction). The light projector 4a
Are provided on the arm 5 supporting the detector 2 so as not to hinder the radiation detection of the detector 2 as clearly shown in FIG. Such a set of the projector 9a and the projector rotating tool 9b can be provided on the opposite side of the subject H as shown by reference numerals 9c and 9d as necessary. Further, the arm 5 is provided with an encoder 10 for detecting a rotation angle θ of the OM line input setting line ff ′ with respect to the vertical projection light gg ′.

Further, the gantry 3 is provided with a traveling drive unit 11 for traveling the gantry body 3 in the body axis direction of the subject. Further, a position sensor 12 for detecting a position of the gantry 3 with respect to the bed 4 (top plate 4a) (hereinafter referred to as a running position) is provided.

On the other hand, the bed 4 has a bed operating section 4 of the bed 4.
A bed driving unit 13 is provided that slides the top plate 4a on the bed 4 in the body axis direction or moves up and down by operating the b.

Next, FIG. 4 shows a schematic system configuration diagram of the ECT 1 according to the present embodiment.

The ECT 1 includes a gantry control unit 14 for controlling the entire gantry 3 and an gantry control unit 1 operated by an operator.
An input unit 15 having, for example, a keyboard for sending various commands to the input unit 4, and an image reconstruction device 17 for performing necessary calculations based on radiation data sent from the detector 2 to reconstruct a tomographic image And a memory 16 for storing the results of calculations performed by the image reconstruction device 17 and the like. The console 18 is composed of the gantry controller 14, the input unit 15, the image reconstruction device 17, and the memory 16.

The gantry control section 14 sends drive signals to the rotation drive section 7 and the travel drive section 11 and sends the drive signals to the arm support section 6 of the gantry 3.
Is rotated around the body axis. In addition, a drive signal is sent to the traveling drive unit 11 to cause the gantry 3 to travel along the body axis direction.

On the other hand, the detection results from the angle sensor 8 and the position sensor 12 are sent to the image reconstruction device 17 via the gantry controller 14.

The image reconstruction device 17 determines the position of the tomographic plane to be reconstructed based on the data sent from the angle sensor 8, the encoder 10, and the position sensor 12.

The arm 5, the support arm 6, and the rotation drive unit 7 form the detector rotation device and the reference line rotation unit (first reference line rotation unit) of the present invention. Further, the light projectors 9a and 9c for projecting linear light respectively form a reference line setting means of the present invention.

Further, the rotating tools 9b and 9d correspond to the second embodiment of the present invention.
Is formed. The rotation angle detector 8 forms the first rotation angle detection means of the present invention, and the encoder 1
0 forms the second rotation angle detecting means of the present invention.

Next, the overall operation will be described.

FIG. 5 is a flowchart showing a procedure from setting an imaging reference line (for example, an OM line) to a patient and executing imaging.

First, a patient (subject) H into which RI has been injected.
Is placed on the top plate 4 a of the bed 4. Then, the bed operating unit 4
By operating b, the bed driving unit 13 is driven to adjust the height of the top board 4a to an optimum state, so that the head of the subject H is at the optimum position with respect to the projector 9a (step 101).

In this state, the operator turns on the light projector 9a and turns on various projection lines as shown in FIG. 3, that is, a horizontal projection light beam ee ', a vertical projection light beam gg', and an OM line input setting line. ff ′ is projected.

At this time, if the subject H is rotated by α ° around the body axis as shown in FIG. 6 due to, for example, a disease in the spine, neck, or the like, the OM line of the subject becomes x (The x-side OM line r _x , y
Side OM line r _y ). Since accurate reconfiguration is not possible with either one of the OM lines, the operator operates the input unit 15 again and sends the arm support unit 6 (that is, the rotating portion of the gantry 3) to the gantry control unit 14. A command to rotate the body axis by α ° in the same direction as the rotating direction is input.

The gantry control section 14 sends a drive signal to the rotation drive section 7 based on this command. As a result, the arm support 6 rotates by α ° in the same direction as the direction in which the body axis rotates. Since the projector 9a is provided on the arm 5 supported by the arm support 6, the projector 9a rotates together with the arm support 6 to be in a state shown in FIG. In other words, the various projection lines (horizontal projection light beam e-e ', vertical projection light beam g-g', and OM line input setting line ff ') are each rotated by?. FIG. 8 shows the positional relationship between the original projection line and the projection line rotated by α ° at this time. FIG. 8 is an enlarged view of the ear canal portion of the subject. As shown in FIG.
e ′, a vertical projection light g−g ′, and an OM line input setting line ff ′ (for convenience, the OM line input setting line ff ′) are newly set as horizontal projection lines e. _1-
e ₁ ′, vertical projection rays g ₁ -g ₁ ′, and OM line input setting lines f ₁ -f ₁ ′.

Next, the operator operates the projector turning tool 9d to set the OM line input setting lines f1-f.
1 ′ is rotated until it coincides with the line connecting the ear hole O and the eye of the subject H, that is, the OM line (the rotation angle is shown as θ in FIG. 3). Thus, the setting of the OM line of the subject H is completed (step 102). The rotation angle θ is detected by the encoder 10,
It is sent to the image reconstruction device 16. The rotation angle α of the subject H around the body axis is detected by the angle sensor 8 as the rotation angle α of the arm support unit 6 and sent to the image reconstruction device 10 via the gantry control unit 14.

After setting the OM line as described above, in order to collect projection data for the head of the subject H, the operator operates the input unit 15 to send the gantry 3 to the gantry control unit 14 and the gantry A in FIG. A command to move from position (broken line position) to position B (solid line position) by distance L is input.

The gantry control section 14 sends a drive signal to the traveling drive section 11 based on this command. As a result, the gantry 3
It moves from position A to position B in FIG. 1 by L (step 103). Note that the movement amount L is detected by the position sensor 12 and is transmitted via the gantry control unit 14 to the image reconstruction apparatus 1.
7

Next, imaging is performed in this state, and the detector 2 collects radiation data.

Here, steps performed by the image reconstruction device 17 until an RI distribution image on the OM line is created based on the collected radiation data will be described with reference to FIG.

In the image reconstruction device 17, the encoder 10
, The rotation angle α detected by the angle sensor 8 and the movement amount L detected by the position sensor 12 are read and temporarily stored in the internal memory 16 (step 201). Then, the actual position of the OM line is calculated based on the rotation angle θ, the rotation angle α, and the movement amount L (step 202).

Here, the processing in step 202 will be described with reference to FIG. FIG. 10 shows the support arm 6,
That is, the relative positional relationship between the projection image P collected when the detector 2 is rotated by α ° and the setting line f ₁ -f ₁ ′ set on the OM line, taking into account the movement amount L of the gantry 3 is shown. I have. In FIG. 10, a line f rotated by θ from the perpendicular g ₁ -g ₁ ′ about the center a of the image in the x direction and the position [(x, y) = (a, L)] of L in the y direction is the center. _1-
f ₁ ′ is the actual position of the OM line.

Thereafter, the projection data sent from the detector 2 is read (step 202), and then the internal memory 17 is read.
, An ECT image when the detector 2 is rotated by α ° is reconstructed (step 203). Shows this ECT image _{I 1} by a solid line in FIG. 11.

[0052] Based on the ECT images I ₁ obtained, the OM line to convert the cross sectional image I2 inclined by an angle θ which forms with these images (shown in phantom). These images become a tomographic image group including the RI tomographic image on the OM line to be finally obtained (step 204).

For example, by adding distance information from the OM line to each inclined tomographic image to the photographing result obtained in this manner, comparison with an X-ray CT apparatus or the like can be performed more easily. Become.

In this embodiment, the light projector 9a is provided on the arm 5. However, the present invention is not limited to this. For example, at a required position of the arm support 6, that is, at a portion that rotates together with the detector 2. Any position may be used as long as it can emit various projection lines to the subject H. Further, separately from the gantry 3, a single rotation mechanism for rotating only the projector 9 a around the body axis of the subject H may be provided.

[0055] Also, projector 9a is, OM line input for setting line _{f-f '(f 1 -f} 1') is rotated along the sagittal plane, while using a so-called rotary-type projector, the present invention is to It is not limited and can be used for a non-rotating floodlight such as a midline floodlight or a side floodlight,
The influence of the displacement due to the rotation of the subject H around the body axis can be eliminated.

Further, the present invention is not limited to the above-described embodiment, and the design can be changed as appropriate without changing the gist of the present invention. For example, in the above embodiment, as shown in FIG. 3, the OM line setting line ff ′
And 'While the intersection O between are shown for the case to match the human ear canal, the invention is not necessarily need to be the case, for example, f 1 _-f' other projection line e-e line This applies to any position of the OM line. In an apparatus such as an MRI apparatus that can acquire a tomographic image in an arbitrary direction without performing cross-sectional conversion, for example, an OM line setting line ff ′ shown in FIG. 2 and its rotation angle θ [FIG. , L), the tomographic plane parallel to the OM line can be easily created.

[0057]

As described above, according to the emission CT apparatus of the present invention, even when the subject is rotated around the body axis by, for example, α °, the imaging reference line (imaging reference line) is similarly set to α. Because it can be rotated by an angle of °, the imaging reference line can be easily adjusted to a required position such as the OM line of the subject. In addition, the reference line setting means does not disturb the radiation detection of the detector.

In particular, for example, a reference line setting means such as a light projector is attached to the detector rotating device, and this detector rotating device is attached to the α °
By rotating, the photographing reference line can be similarly rotated by α °, so that the photographing reference line can be adjusted to a required position such as an OM line with fewer components.

Further, the rotation angle of the reference line rotation means is detected,
Based on the rotation angle and the radiation data detected by the detector, a slice image corresponding to the imaging reference line can be reconstructed, so that the slice image is accurate and can be rotated around the body axis of the subject. Can be created independently.

Further, for example, the imaging reference line is set to the OM of the subject.
When the subject is rotated by α ° around the body axis when aligning with the line (which is not perpendicular to the rotation axis of the detector but inclined along the sagittal plane), the imaging reference line is To α
By rotating the imaging reference line with the OM line by rotating the imaging reference line by β ° along the sagittal plane passing through the body axis of the subject, the rotation angle (α, β ) And the radiation data detected by the detector, a slice image corresponding to the imaging reference line can be reconstructed. Therefore, the slice image can be created accurately and irrespective of the position and rotation of the subject about the body axis.

[Brief description of the drawings]

FIG. 1 is a side view showing an ECT in the present embodiment.

FIG. 2 is a front view of the ECT in the embodiment.

FIG. 3 is a view showing various projection lines in the embodiment.

FIG. 4 is a system configuration diagram of an ECT in the embodiment.

FIG. 5 is a schematic flowchart showing an example of an operation procedure of an operator in the embodiment.

FIG. 6 is a diagram showing a shift of an OM line in the embodiment.

FIG. 7 is a diagram showing a state where the detector is rotated by α.

FIG. 8 is a view for explaining movement of various projection lines due to rotation of the detector by α.

FIG. 9 is a schematic flowchart illustrating an example of a process performed by the image reconstruction device.

FIG. 10 is a view for explaining the steps in the flowchart shown in FIG. 8;

FIG. 11 is a view for explaining the steps in the flowchart shown in FIG. 8;

FIG. 12 is a configuration diagram showing an example of a conventional ECT.

FIG. 13 is a diagram showing a deviation of an OM line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ECT 2 Detector 3 Cradle 4 Bed 4a Top plate 4b Bed operation part 5 Arm 6 Arm support part 7 Rotation drive part 8 Angle sensor 9a Projector 9b Projector rotator 9c Projector 9d Projector rotator 10 Encoder 11 Position drive part 13 Sleeper drive unit 18 Console

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01T 1/161

Claims (4)

(57) [Claims] 1. A detector for detecting radiation emitted from a subject into which RI has been injected, and a detector provided at a position avoiding a detection path of the radiation detected by the detector, and imaging on the subject. Reference line setting means for setting a reference line for use; reference line rotating means for rotating the reference line around the body axis of the subject; and a rotation angle of the reference line rotated by the reference line rotating means. A rotation angle detecting means for detecting, and a tomographic image of the subject corresponding to the reference line is reconstructed based on data of the radiation detected by the detector and the rotation angle detected by the rotation angle detecting means. An emission CT apparatus comprising an image reconstruction device. 2. A detector for detecting radiation emitted from a subject into which RI has been injected, a detector rotating device for rotating the detector around a body axis of the subject, and the detector rotating device. A reference line setting means attached to a position avoiding a detection path of radiation detected by the detector, and setting a reference line for imaging on the subject; and setting the reference line to a body axis of the subject. Reference line rotating means for rotating around the reference line, rotation angle detecting means for detecting the rotation angle of the reference line rotated by the reference line rotating means, radiation data detected by the detector and the rotation angle detection An image reconstruction apparatus configured to reconstruct a tomographic image of the subject corresponding to the reference line based on the rotation angle detected by the means. 3. A detector for detecting radiation emitted from a subject into which RI has been injected, reference line setting means for setting a reference line for imaging on the subject, and setting the reference line to the subject. First reference line rotating means for rotating about the body axis of the subject; second reference line rotating means for rotating the reference line along a plane parallel to the body axis of the subject; and the body of the reference line First rotation angle detection means for detecting a rotation angle of the first reference line rotation means with rotation about an axis; and the second rotation angle detection means with rotation of the reference line along a plane parallel to the body axis. Second rotation angle detection means for detecting a rotation angle of a reference line rotation means; data of radiation detected by the detector;
And an image reconstruction device for reconstructing a tomographic image of the subject corresponding to the reference line based on the rotation angles detected by the second rotation angle detection means. 4. The apparatus according to claim 3, further comprising a detector rotating device for rotating the detector around a body axis of the subject, wherein the first reference line rotating means is attached to the detector rotating device. Emission CT device.