RADIATION TOMOGRAPHY APPARATUS
A detector ring has a first unit and a second unit that are rotatably movable and an auxiliary unit movable in a central axis direction. The auxiliary unit is moved in the central axis direction relative to the units. The detector ring forms into a C shape to form a clearance. Subsequently, the first unit and the second unit are rotatably moved to move the clearance of the detector ring to a position distant from a support member. A patient can be introduced from the clearance. The detector ring is returned to an annular shape in the reverse sequence of the above one with the patient introduced. A annihilation radiation pairs can be detected from all directions to take a tomographic image, and a functional image with higher image quality than that of a conventional configuration can be obtained.
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The present invention relates to a radiation tomography apparatus that detects annihilation radiation pairs emitted from a patient to image radioactive agent distribution within the patient and, in particular, to a radiation tomography apparatus used in combination with another imaging apparatus.
BACKGROUND ARTRadiation tomography apparatuses that image the distribution of a radioactive agent are deployed in medical institutions. The following describes a specific configuration of such a radiation tomography apparatus. A conventional radiation tomography apparatus includes a detector ring including radiation detectors annularly arranged and detecting radiations. This detector ring detects a pair of radiations that are emitted from a radioactive agent within a patient and are opposite in direction to each other (an annihilation radiation pair). Such an apparatus is called a positron emission tomography (PET) apparatus.
Given these circumstances, as illustrated in
The following describes the reason why the PET apparatus and the CT apparatus are arranged close to each other. Suppose that the PET apparatus and the CT apparatus are prepared in different inspection rooms, for example. In such a configuration, a morphological image is first taken with the CT apparatus, then the patient is moved to another room, and a functional image is taken with the PET apparatus. In such as a configuration, the morphological image and the functional image cannot be precisely superimposed on one another. This is because the postures of the patient when imaged by the respective apparatuses are different from each other. To reduce such image discrepancy, the PET apparatus and the CT apparatus are provided close to each other. By doing so, once the patient is placed on a patient couchpatient couch, there is no need to take down the patient from the patient couchpatient couch until capture of the morphological image and the functional image ends. The apparatus in
However, imaging with the CT apparatus creates a large amount of exposure dose and is not suitable for pregnant women, children, and the like, who have high radiosensitivity. Hence, apparatuses gradually in common in recent years are a PET/MRI apparatus whose CT apparatus illustrated in
The patient couch included in the MRI apparatus has a long, narrow shape to fit the patient. The patient couch is movable in a longitudinal direction (the body axis direction of the patient placed on the patient couch). This is because the patient is required to be introduced into a gantry of the MRI apparatus. The mobile type PET apparatus is brought close to and separated from the patient couch in the lateral direction of the patient couch (the body side direction of the patient placed on the patient couch) as indicated by the arrow in
Essentially, the detector ring is desirably annularly shaped. If it is not so shaped, annihilation radiation pairs are unevenly detected, making it difficult for a clear functional image to be taken. However, the clearance A has to be provided to the mobile type PET apparatus because a path is required to introduce the patient through the path. Consequently, in the conventional configuration, after the patient is introduced, the detector ring is transformed to divide the clearance A, whereby the influence of the clearance A appearing in the functional image is ingeniously reduced to a minimum.
CITATION LIST Non-Patent Document
- NON-PATENT DOCUMENT 1: Y. Yoshiyuki, et al., “Development of a dual-head mobile DOI-TOF PET system having multi-modality compatibility,” in Conf. Rec. IEEE NSS/MIC, 2014, M11-69.
The conventional configuration has the following problem.
In other words, the conventional configuration does not completely reduce image degradation caused by providing the clearance in the detector ring.
Although the conventional configuration reduces image degradation caused by the provided clearance A, image degradation cannot yet be completely prevented. To achieve clearer image quality, PET imaging is desirably performed using an annularly shaped detector ring.
However, the mobile type PET apparatus requires the clearance A to introduce the patient. Consequently, it is also difficult not to provide the clearance A.
The present invention has been made in view of such circumstances, and an object thereof is to provide a radiation tomography apparatus that can generate a functional image with good image quality by providing a detector ring that is annularly shaped and can introduce the patient from a direction orthogonal to a central axis.
Solution to the ProblemTo solve the problems described above, the present invention has the following configuration.
In other words, the radiation tomography apparatus according to the present invention includes: a detector ring including (i) a first unit including radiation detectors arranged in an arc and detecting radiations, (ii) a second unit including the radiation detectors arranged in an arc, and (iii) an auxiliary unit including the radiation detectors arranged in an arc, such that the radiation detectors included in the first unit, the second unit, and the auxiliary unit are arranged annularly; a support member that supports the detector ring and is provided close to the auxiliary unit among the units; an auxiliary unit mover that moves the auxiliary unit in a central axis direction of the detector ring relative to the first unit and the second unit; a first unit rotator that rotatably moves the first unit about the central axis; and a second unit rotator that rotatably moves the second unit about the central axis.
AdvantagesThe present invention can provide a radiation tomography apparatus that can generate a functional image with good image quality. In other words, in the configuration of the present invention, the annular-shaped detector ring has the first unit and the second unit that are rotatably movable and the auxiliary unit movable in the central axis direction. The auxiliary unit is moved in the central axis direction relative to the units, whereby the detector ring forms into a C shape to form a clearance.
However, the support member supporting the auxiliary unit is positioned near this clearance. Hence, in the present invention, the first unit and the second unit are rotatably moved additionally to move the clearance of the detector ring to a position distant from the support member. By doing so, a patient can be introduced from a direction orthogonal to the central axis of the detector ring without interference from the support member. The detector ring is restored to the annular shape in the reverse sequence of the above one with the patient introduced, whereby annihilation radiation pairs can be detected from all directions to take a tomographic image, and a functional image with higher image quality than that of a conventional configuration can be obtained.
In the present invention, all the members included in the detector ring are supported on the single support member. With this configuration, the positional relationship among the units included in the detector ring can be reliably maintained constant. In this regard, in a configuration in which the units are supported on separate support members, when the positional relationship among the support members changes, the shape of the detector ring also changes. The present invention is free from such an inconvenience.
In the radiation tomography apparatus described above, the first unit rotator may rotate the first unit and the second unit rotator may rotate the second unit to bring the first unit and the second unit close to the support member, so that end parts of the first unit and the second unit, adjacent to each other before the rotations, may be separated from each other, and a clearance may be generated between the first unit and the second unit such that, through the clearance, a patient may be introduced inside the detector ring from a direction orthogonal to the central axis.
In the radiation tomography apparatus described above, the first unit rotator may rotate the first unit and the second unit rotator may rotate the second unit to separate the first unit and the second unit from the support member, so that end parts of the first unit and the second unit, adjacent to each other before the rotations, may be separated from each other, and a clearance may be generated between the first unit and the second unit such that, through the clearance, the auxiliary unit may be introduced from a direction in which the central axis extends.
AdvantagesThe configuration described above can reliably achieve the configuration of the present invention.
The radiation tomography apparatus described above may desirably include a first arc guide fixing the first unit and a second arc guide fixing the second unit, in which the first unit rotator rotates the first guide to perform rotational movement of the first unit, and the second unit rotator rotates the second guide to perform rotational movement of the second unit.
AdvantagesThe configuration described above can provide an apparatus that can reliably rotate the units.
The radiation tomography apparatus described above may desirably include an arc guide supporting the first unit and the second unit, in which the first unit rotator moves the first unit relative to the guide to perform rotational movement of the first unit, and the second unit rotator moves the second unit relative to the guide to perform rotational movement of the second unit.
AdvantagesThe configuration described above can make the configuration of the apparatus simpler than the configuration including the first guide and the second guide.
The radiation tomography apparatus described above may desirably include a vehicle moving the detector ring in a direction orthogonal to the central axis.
Action and EffectThe configuration described above allows the entire apparatus to be moved close to the patient mounted on a patient couch from the body side direction of the patient.
The radiation tomography apparatus described above may desirably include a support member elevator that raises and lowers the support member to raise and lower the detector ring.
AdvantagesThe configuration described above can align the patient and the detector ring with each other with the positional relationship reliably maintained among the members included in the detector ring.
The radiation tomography apparatus described above may desirably be arranged in an MRI apparatus.
The radiation tomography apparatus described above may desirably be arranged in a CT apparatus.
AdvantagesThe present invention can be used in combination with the MRI apparatus or the CT apparatus.
Advantages of the InventionThe present invention can provide a radiation tomography apparatus that can generate a functional image with good image quality. In other words, in the configuration of the present invention, an annular-shaped detector ring has a first unit and a second unit that are rotatably movable and an auxiliary unit movable in a central axis direction. The auxiliary unit is moved in the central axis direction of the detector ring relative to the units, whereby the detector ring forms into a C shape to form a clearance. Subsequently, the first unit and the second unit are rotatably moved to move a clearance of the detector ring to a position distant from a support member, whereby a patient can be introduced from the clearance. The detector ring is restored to an annular shape in the reverse sequence of the above one with the patient introduced, whereby annihilation radiation pairs can be detected from all directions to take a tomographic image, and a functional image with higher image quality than that of a conventional configuration can be obtained.
The following describes embodiments of the present invention with reference to an example. A radiation tomography apparatus according to the present invention is a PET apparatus that injects a compound labeled with a positron emission type radioactive isotope into a patient and detects annihilation radiation pairs to image the distribution of the compound within the body of the patient. The following example describes a PET apparatus used in combination with an MRI apparatus.
Example 1To a coincidence counter 21 (see
The coincidence counter 21 sends data indicating the result of counting to an image generation unit 22. Based on the sent data, the image generation unit 22 images the distribution of the radioactive agent in the imaging fields of view positioned inside the detector ring 12, and generates a tomographic image.
<Configuration of Support Member Elevation Mechanism 31>
A support member elevation mechanism 31 is provided in the vehicle 10 and raises and lowers the support member 15 relative to the vehicle 10. When the support member 15 is raised and lowered by the support member elevation mechanism 31, as illustrated in
<Division of Detector Ring 12>
The detector ring 12 of the present invention includes three members annularly arranged and capable of mutually changing their positional relationship. In other words, the detector ring 12 includes a first unit 12a, a second unit 12b, and an auxiliary unit 12c formed in an arc and arranged to form a circle. The auxiliary unit 12c among them is positioned closest to the support member 15. The first unit 12a, the second unit 12b, and the auxiliary unit 12c include radiation detectors 1 arranged in an arc and detecting radiations. The first unit 12a, the second unit 12b, and the auxiliary unit 12c are arranged in an arc to form the detector ring 12 in which the radiation detectors 1 are annularly arranged. The support member 15 supports the detector ring 12 and is provided adjacent to the auxiliary unit 12c among the units 12a, 12b, and 12c.
<Relationship Between Units and Guides>
The units 12a, 12b, and 12c included in the detector ring 12 are supported on the respective guides 13a, 13b, and 13c in order to move the respective units. The following describes this configuration.
The second arc guide 13b is fixed to the second unit 12b. The second guide 13b is offset toward the central axis c of the detector ring 12 relative to the second unit 12b. In
The first guide 13a and the second guide 13b thus are offset from each other in different directions relative to the detector ring 12. Being thus configured, the first guide 13a and the second guide 13b do not interfere with each other. In other words, the guides 13a and 13b are in a different position form each other in the central axis c direction, and even when the first guide 13a and the second guide 13b are rotated about the central axis c, the guides 13a and 13b do not collide with each other.
The auxiliary unit 12c is provided with an arc auxiliary guide 13c. It should be noted that this auxiliary guide 13c is not fixed to the auxiliary unit 12c. The slide rail 16 extending parallel to the central axis is fixed to the auxiliary unit 12c. The auxiliary guide 13c supports this slide rail 16 in a movable manner in the central axis direction.
<About Unit Slide Mechanism 32>
<Unit Rotation Mechanisms 33a and 33b>
When the auxiliary unit 12c forms the detector ring 12 as in
The left side in
In other words, after having moved relative to the units 12a and 12b, the unit rotation mechanism 33a rotatably moves the first unit 12a about the central axis, whereas after having moved relative to the units 12a and 12b, a unit rotation mechanism 33b rotatably moves the second unit 12b about the central axis. The unit rotation mechanisms 33b corresponds to a second unit rotator of the present invention.
Such motions of the units 12a and 12b are performed by the respective guides 13a and 13b. In other words, the guides 13a and 13b are supported on the arc rotation base 14. The rotation base 14 is a guide when the first guide 13a rotatably moves, and the first guide 13a follows the locus of an arc in accordance with the shape of the rotation base 14. The center of this rotation overlaps with the central axis c of the detector ring 12. In other words, the first guide 13a is supported on the rotation base 14 in a movable manner. The first unit 12a follows this first guide 13a to rotatably move.
These circumstances hold true for the second guide 13b. In other words, the rotation base 14 is a guide when the second guide 13b rotatably moves, and the second guide 13b follows the locus of an arc in accordance with the shape of the rotation base 14. The center of this rotation overlaps with the central axis c of the detector ring 12. In other words, the second guide 13b is supported on the rotation base 14 in a movable manner. The second unit 12b follows this second guide 13b to rotatably move.
In other words, the apparatus according to the present invention includes the first arc guide 13a fixing the first unit 12a and the second arc guide 13b fixing the second unit 12b. The unit rotation mechanism 33a rotates the first guide 13a to perform rotational movement of the first unit 12a, whereas the unit rotation mechanism 33b rotates the second guide 13b to perform rotational movement of the second unit 12b.
The rotation base 14 is fixed to the support member 15. Consequently, even when the units 12a and 12b rotate, the rotation base 14 does not move relative to the support member 15.
<Introduction of Patient M>
The following describes a method for introducing the patient M into the apparatus according to Example 1.
The patient M can be introduced into the detector ring 12 from this clearance produced in the detector ring 12. The following describes this point. On the right side in
The radiation tomography apparatus includes the vehicle 10, and the entire apparatus can be moved in the body side direction of the patient M (the right-and-left direction in
In the apparatus according to the present invention, the unit rotation mechanism 33a and the unit rotation mechanism 33b cooperatively work upon the detector ring 12, in which the auxiliary unit 12c has moved relative to the units 12a and 12b, to rotate the units 12a and 12b to the left side (to bring the units 12a and 12b close to the support member 15) (see
<Most Characteristic Feature of the Present Invention: Transformation of Detector Ring 12>
The following describes the most characteristic feature of the present invention. In other word, the detector ring 12 according to the present invention can transform from a C shape into an annular shape with the patient M introduced. To perform this transformation, first, the units 12a and 12b are rotatably moved. In other words, operation in the reverse sequence of the illustration in
Thus, in the present invention, the unit rotation mechanism 33a and the unit rotation mechanism 33b rotate the respective units 12a and 12b to separate that the respective units 12a and 12b from the support member 15, so that the end parts of the respective units 12a and 12b, adjacent to each other before the rotations, are separated from each other, and a clearance is generated between the units 12a and 12b such that, through the clearance, the auxiliary guide 13c is introduced from a direction in which the central axis c extends.
As described above, the present invention can provide a radiation tomography apparatus that can generate a functional image with good image quality. In other words, in the configuration of the present invention, the annular-shaped detector ring 12 has the first unit 12a and the second unit 12b that are rotatably movable and the auxiliary unit 12c movable in the central axis direction. The auxiliary unit 12c is moved in the central axis direction relative to the units 12a and 12b, whereby the detector ring 12 forms into a C shape to form a clearance.
However, the support member 15 supporting the auxiliary unit 12c is positioned near this clearance. Hence, in the present invention, the first unit 12a and the second unit 12b are rotatably moved additionally to move the clearance of the detector ring 12 to a position distant from the support member 15. By doing so, the patient M can be introduced from a direction orthogonal to the central axis c of the detector ring 12 without interference from the support member 15. The detector ring 12 is restored to the annular shape in the reverse sequence of the above one with the patient M introduced, whereby annihilation radiation pairs can be detected from all directions to take a tomographic image, and a functional image with higher image quality than that of a conventional configuration can be obtained.
In the present invention, all the members included in the detector ring 12 are supported on the single support member 15. With this configuration, the positional relation among the units 12a, 12b, and 12c included in the detector ring 12 can be reliably fixed. In this regard, in a configuration in which the units 12a, 12b, and 12c are supported on separate support members 15, when the positional relation among the support members 15 changes, the shape of the detector ring 12 also changes. The present invention is free from such an inconvenience.
The present invention is not limited to the configuration described above and can be performed in a modified manner as follows.
(1) Although the guides 13a and 13b supporting the respective units 12a and 12b rotatably move to rotate the respective units 12a and 12b in the configuration described above, the present invention is not limited to this configuration. As illustrated in
In other words, the apparatus according to the present modification includes the arc guide 13 supporting the first unit 12a and the second unit 12b. The unit rotation mechanism 33a moves the first unit 12a relative to the guide 13 to perform rotational movement of the first unit 12a, whereas the unit rotation mechanisms 33b moves the second unit 12b relative to the guide 13 to perform rotational movement of the second unit 12b.
The present modification can make the apparatus configuration simpler.
(2) Although the configuration described above divides the detector ring 12 into three, each of which is moved, the present invention is not limited to this configuration; the detector ring 12 may be divided into four or more.
(3) Although the configuration described above is used in combination with the MRI apparatus, the present invention is not limited to this configuration. The present invention can also be used in combination with another apparatus such as a CT apparatus.
(4) Although the mechanisms 31, 32, 33a, and 33b of the present invention are manually operated, the mechanism can also be automatically moved in place of this configuration. In this modification, a controller that controls the mechanisms is provided.
DESCRIPTION OF REFERENCE CHARACTERS
- 1 Radiation Detector
- 12a First Unit
- 12b Second Unit
- 12c Auxiliary Unit
- 12 Detector Ring
- 15 Support Member
- 32 Unit Slide Mechanism (Auxiliary Unit Mover)
- 33a Unit Rotation Mechanism (First Unit Rotator)
- 33b Unit Rotation Mechanism (Second Unit Rotator)
Claims
1-9. (canceled)
10. A radiation tomography apparatus comprising:
- a detector ring including a first unit including radiation detectors arranged in an arc and detecting radiations, a second unit including the radiation detectors arranged in an arc, and an auxiliary unit including the radiation detectors arranged in an arc, such that the radiation detectors included in the first unit, the second unit, and the auxiliary unit are arranged annularly;
- a support member that supports the detector ring and is provided close to the auxiliary unit among the respective units;
- an auxiliary unit mover that moves the auxiliary unit in a central axis direction of the detector ring relative to the first unit and the second unit;
- a first unit rotator that rotatably moves the first unit about the central axis; and
- a second unit rotator that rotatably moves the second unit about the central axis.
11. The radiation tomography apparatus of claim 10, wherein
- the first unit rotator rotates the first unit and the second unit rotator rotates the second unit to bring the first unit and the second unit close to the support member, so that end parts of the first unit and the second unit, adjacent to each other before the rotations, are separated from each other, and a clearance is generated between the first unit and the second unit such that, through the clearance, a patient is introduced inside the detector ring from a direction orthogonal to the central axis.
12. The radiation tomography apparatus of claim 10, wherein the first unit rotator rotates the first unit and the second unit rotator rotates the second unit to separate the first unit and the second unit from the support member, so that end parts of the first unit and the second unit, adjacent to each other before the rotations, are separated from each other, and a clearance is generated between the first unit and the second unit such that, through the clearance, the auxiliary unit is introduced from a direction in which the central axis extends.
13. The radiation tomography apparatus of claim 10, further comprising:
- a first arc guide fixing the first unit; and
- a second arc guide fixing the second unit, wherein
- the first unit rotator rotates the first guide to perform rotational movement of the first unit, and
- the second unit rotator rotates the second guide to perform rotational movement of the second unit.
14. The radiation tomography apparatus of claim 10, further comprising:
- an arc guide supporting the first unit and the second unit, wherein
- the first unit rotator moves the first unit relative to the guide to perform rotational movement of the first unit, and
- the second unit rotator moves the second unit relative to the guide to perform rotational movement of the second unit.
15. The radiation tomography apparatus of claim 10, further comprising:
- a vehicle moving the detector ring in a direction orthogonal to the central axis.
16. The radiation tomography apparatus of claim 10, further comprising:
- a support member elevator that raises and lowers the support member to raise and lower the detector ring.
17. The radiation tomography apparatus of claim 10 arranged in an MRI apparatus.
18. The radiation tomography apparatus of claim 10 arranged in a CT apparatus.
Type: Application
Filed: Jan 16, 2017
Publication Date: Mar 14, 2019
Applicant: Shimadzu Corporation (Kyoto)
Inventor: Junichi OHI (Kyoto)
Application Number: 16/084,276