U.S. patent application number 16/084276 was filed with the patent office on 2019-03-14 for radiation tomography apparatus.
This patent application is currently assigned to Shimadzu Corporation. The applicant listed for this patent is Shimadzu Corporation. Invention is credited to Junichi OHI.
Application Number | 20190079203 16/084276 |
Document ID | / |
Family ID | 60326498 |
Filed Date | 2019-03-14 |
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United States Patent
Application |
20190079203 |
Kind Code |
A1 |
OHI; Junichi |
March 14, 2019 |
RADIATION TOMOGRAPHY APPARATUS
Abstract
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.
Inventors: |
OHI; Junichi; (Kyoto,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shimadzu Corporation |
Kyoto |
|
JP |
|
|
Assignee: |
Shimadzu Corporation
Kyoto
JP
|
Family ID: |
60326498 |
Appl. No.: |
16/084276 |
Filed: |
January 16, 2017 |
PCT Filed: |
January 16, 2017 |
PCT NO: |
PCT/JP2017/001221 |
371 Date: |
September 12, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 6/4441 20130101;
G01T 1/202 20130101; A61B 6/4266 20130101; G01T 1/164 20130101;
G01T 1/2985 20130101; G01T 1/161 20130101; A61B 6/4405 20130101;
A61B 6/4258 20130101; A61B 6/032 20130101; A61B 6/037 20130101;
A61B 6/4429 20130101; G01T 1/1612 20130101 |
International
Class: |
G01T 1/29 20060101
G01T001/29; A61B 6/03 20060101 A61B006/03; G01T 1/164 20060101
G01T001/164; A61B 6/00 20060101 A61B006/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 19, 2016 |
JP |
2016-100338 |
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.
Description
TECHNICAL FIELD
[0001] 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 ART
[0002] Radiation 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.
[0003] FIG. 17 illustrates a typical PET apparatus. The PET
apparatus is of the stationary type fixed to a floor of a
inspection room, and a patient is introduced from an opening
provided in the PET apparatus. An image obtained by this PET
apparatus means the distribution of the radioactive agent within
the patient. Consequently, the distribution of a
highly-concentrated radioactive agent on this image would not
always definitely indicate which organ of the patient.
[0004] Given these circumstances, as illustrated in FIG. 17, an
image imaging apparatus including both the PET apparatus and a CT
apparatus has been devised and widely used. The CT apparatus of
this imaging apparatus gives a morphological image showing the
internal structure of the patient, whereas the PET apparatus gives
a functional image showing the distribution of the radioactive
agent. When morphological image and the functional image are
displayed in a superimposed manner, a viewer of the images can tell
which part of the patient the radioactive agent has been
distributed.
[0005] 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 FIG. 17, allows the CT and
PET apparatuses to finish imaging while the patient maintains the
same posture, such that the obtained morphological image and
functional image can be precisely superimposed on one another.
[0006] 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 FIG. 17 is replaced
with an MRI apparatus, and a completely integral type PET/MRI
apparatus in which detectors of a PET apparatus are contained
within an imaging field of view of an MRI apparatus. However, the
PET/MRI apparatus is large-scale in configuration, and the price of
the apparatus itself tends to be extraordinarily high. Some medical
institutions already having an MRI apparatus may desire a PET
apparatus that can be placed by the side of the MRI apparatus. In
view of such a need, a mobile type PET apparatus as illustrated in
FIG. 18 has been devised in recent years. In this mobile type PET
apparatus, when a patient is placed on a patient couch included in
the MRI apparatus, a functional image can be taken without moving
the patient from this patient couch (see NON-PATENT DOCUMENT 1, for
example).
[0007] 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 FIG. 18. When imaging is
performed with the PET apparatus, the patient and the patient couch
are required to be introduced inside the detector ring. In a
conventional configuration, for the purpose of introducing the
detector ring from the body side direction of the patient, the
detector ring is provided with a clearance A. This clearance A
makes the detector ring form into a C shape.
[0008] FIG. 19 illustrates how the patient is actually introduced
inside the detector ring. The detector ring is provided with the
clearance A, whereby the patient and the patient couch are
introduced into the center of the detector ring without being
interfered with the detector ring.
[0009] FIG. 20 illustrates the transformation of the detector ring
performed before starting PET imaging. In other words, the detector
ring immediately after the introduction of the patient illustrated
on the left side in FIG. 20 is transformed so that the transformed
detector ring vertically sandwiches a patient M therebetween as
illustrated on the right side in FIG. 20. The detector ring of the
mobile type PET apparatus forms a C shape by combining two arc
members with each other. These members can rotate and move about
the central point of the detector ring. With this movement, the
clearance A appearing on the right side of the detector ring is
divided into right and left.
[0010] 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
[0011] 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.
SUMMARY OF THE INVENTION
Technical Problem
[0012] The conventional configuration has the following
problem.
[0013] In other words, the conventional configuration does not
completely reduce image degradation caused by providing the
clearance in the detector ring.
[0014] 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.
[0015] 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.
[0016] 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 Problem
[0017] To solve the problems described above, the present invention
has the following configuration.
[0018] 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.
Advantages
[0019] 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 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] 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.
Advantages
[0024] The configuration described above can reliably achieve the
configuration of the present invention.
[0025] 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.
Advantages
[0026] The configuration described above can provide an apparatus
that can reliably rotate the units.
[0027] 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.
Advantages
[0028] The configuration described above can make the configuration
of the apparatus simpler than the configuration including the first
guide and the second guide.
[0029] 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 Effect
[0030] The 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.
[0031] 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.
Advantages
[0032] The 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.
[0033] The radiation tomography apparatus described above may
desirably be arranged in an MRI apparatus.
[0034] The radiation tomography apparatus described above may
desirably be arranged in a CT apparatus.
Advantages
[0035] The present invention can be used in combination with the
MRI apparatus or the CT apparatus.
Advantages of the Invention
[0036] 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, 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a functional block diagram illustrating an entire
configuration of a radiation tomography apparatus according to
Example 1.
[0038] FIG. 2 is a schematic diagram illustrating a detector ring
according to Example 1.
[0039] FIG. 3 is a perspective view illustrating a detector
according to Example 1.
[0040] FIG. 4 is a schematic diagram illustrating a support member
elevation mechanism according to Example 1.
[0041] FIG. 5 is an exploded perspective view illustrating units
included in the detector ring according to Example 1.
[0042] FIG. 6 is a perspective view illustrating the units included
in the detector ring according to Example 1.
[0043] FIG. 7 is a schematic diagram illustrating the movement of
an auxiliary unit according to Example 1.
[0044] FIG. 8 is a schematic diagram illustrating a unit slide
mechanism according to Example 1.
[0045] FIG. 9 is a schematic diagram illustrating unit rotational
motion according to Example 1.
[0046] FIG. 10 is a schematic diagram illustrating an operation to
introduce a patient according to Example 1.
[0047] FIG. 11 is a schematic diagram illustrating the operation to
introduce the patient according to Example 1.
[0048] FIG. 12 is a schematic diagram illustrating the operation to
introduce the patient according to Example 1.
[0049] FIG. 13 is a schematic diagram illustrating an operation to
transform the detector ring according to Example 1.
[0050] FIG. 14 is a schematic diagram illustrating the operation to
transform the detector ring according to Example 1.
[0051] FIG. 15 is a schematic diagram illustrating the operation to
transform the detector ring according to Example 1.
[0052] FIG. 16 is a schematic diagram illustrating a modification
according to the present invention.
[0053] FIG. 17 is a schematic diagram illustratinclearanceET
apparatus of a conventional configuration.
[0054] FIG. 18 is a schematic diagram illustrating a mobile type
PET apparatus of a conventional configuration.
[0055] FIG. 19 is a schematic diagram illustrating a method for
introducing a patient of a conventional configuration.
[0056] FIG. 20 is a schematic diagram illustrating a method of
imaging of a conventional configuration.
DESCRIPTION OF EMBODIMENTS
[0057] 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 1
[0058] FIG. 1 illustrates units included in the radiation
tomography apparatus according to the present invention. The
radiation tomography apparatus according to the present invention
includes a vehicle 10 having wheels and a detector ring 12
installed on the vehicle 10. As illustrated in FIG. 2, the detector
ring 12 includes radiation detectors 1 detecting radiations
arranged in an arc. A support member 15 supports one end of the
detector ring 12 to support the entire detector ring 12.
Specifically, the support member 15 supports each of a first guide
13a, a second guide 13b, and an auxiliary guide 13c described below
to support the detector ring 12. All loads of the detector ring 12
and the guides 13a, 13b, and 13c are supported on the single
support member 15. The vehicle 10 moves the detector ring 12 in a
direction orthogonal to a central axis c.
[0059] FIG. 3 illustrates a configuration of the radiation detector
1. The radiation detector 1 includes a scintillator 2 including
scintillator crystals that convert radiations (gamma rays) into
fluorescence arranged in a three-dimensional manner in three, or
longitudinal, lateral, and height, directions. The scintillator 2
is optically coupled to a light guide 4 that passes the
fluorescence, and the light guide 4 is optically coupled to an
optical detector 3 detecting fluorescence. Consequently, the light
guide 4 is arranged at a position interposed between the
scintillator 2 and the optical detector 3. When the fluorescence is
generated in the scintillator 2, the optical detector 3 can
determine which scintillator crystal generates the
fluorescence.
[0060] To a coincidence counter 21 (see FIG. 1), a detection signal
output from the detector ring 12 is sent. Two gamma rays that have
coincidentally entered the detector ring 12 are a radiation pair
caused by a radioactive agent within the patient. The coincidence
counter 21 counts how many radiation pairs have been detected for
each combination of two scintillator crystals among the
scintillator crystals included in the detector ring 12. For the
determination of the coincidence of the detection signal by the
coincidence counter 21, time information imparted to the detection
signal by a clock is used. The detection signal sent to the
coincidence counter 21 indicates a result of detecting radiations
caused by the radioactive agent administered to a patient M. The
detection signal output by the coincidence counter 21 is a result
of detecting the radiation pair emitted from any given part of the
imaging field of view of the detector ring 12 and is a result of
measuring the radiation pair throughout the entire detector ring
12.
[0061] 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.
[0062] <Configuration of Support Member Elevation Mechanism
31>
[0063] 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 FIG.
4, the detector ring 12, the guides 13a, 13b, and 13c, and a
rotation base 14 and a slide rail 16 described below follow the
support member 15 to be raised and lowered with their mutual
positional relationship maintained. The support member elevation
mechanism 31 raises and lowers the support member 15 to raise and
lower the detector ring 12. The support member elevation mechanism
31 corresponds to a support member elevator of the present
invention.
[0064] <Division of Detector Ring 12>
[0065] 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.
[0066] <Relationship Between Units and Guides>
[0067] 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. FIG. 5 is an exploded perspective view of the
detector ring 12 and illustrates the respective guides similarly.
The first arc guide 13a is fixed to the first unit 12a. The first
guide 13a is offset toward a central axis c of the detector ring 12
relative to the first unit 12a. In FIG. 5, the first guide 13a is
offset upward relative to the first unit 12a.
[0068] 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 FIG. 5, the
second guide 13b is offset downward relative to the second unit
12b.
[0069] 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.
[0070] 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.
[0071] FIG. 5, because of being an exploded perspective view,
illustrates the units 12a, 12b, and 12c so that the units 12a, 12b,
and 12c are in a different position in the central axis c
direction. However, the units 12a, 12b, and 12c are actually in the
same position relative to the central axis c direction and form one
detector ring 12 as illustrated in FIG. 6. In FIG. 6, the guides
13a, 13b, and 13c are omitted.
[0072] <About Unit Slide Mechanism 32>
[0073] FIG. 7 illustrates how the auxiliary unit 12c moves in the
central axis direction relative to the auxiliary guide 13c. With
this motion, as illustrated in FIG. 8, the auxiliary unit 12c can
move in the central axis c direction relative to the units 12a and
12b. With this movement, the detector ring 12 changes from the
annular shape formed with the units 12a, 12b, and 12c to a C shape
formed with the units 12a and 12b because the auxiliary unit 12c
moves in the central axis c direction. This motion of the auxiliary
unit 12c is performed by a unit slide mechanism 32. In other words,
the auxiliary guide 13c is fixed to the support member 15, and the
auxiliary unit 12c moves relative to the auxiliary guide 13c and
thereby moves relative to the support member 15 and the units 12a
and 12b supported thereby. The auxiliary guide 13c and the slide
rail 16 are included in the members included in the unit slide
mechanism 32. The unit slide mechanism 32. moves the auxiliary unit
12c in the central axis c direction of the detector ring 12 and
moves the auxiliary unit 12c relative to the units 12a and 12b. The
unit slide mechanism 32 corresponds to an auxiliary unit mover of
the present invention.
[0074] <Unit Rotation Mechanisms 33a and 33b>
[0075] When the auxiliary unit 12c forms the detector ring 12 as in
FIG. 6, the units 12a and 12b cannot be rotated about the central
axis c. However, when the auxiliary unit 12c moves relative to the
units 12a and 12b to form a broken ring in which part of the
detector ring 12 is broken as in FIG. 8, the units 12a and 12b can
rotate. In fact, the apparatus according to the present invention
can rotate the units 12a and 12b. The following describes this
point. A unit rotation mechanism 33a corresponds to a first unit
rotator of the present invention.
[0076] The left side in FIG. 9 illustrates a state in which the
auxiliary unit 12c has moved relative to the units 12a and 12b. At
this moment, it is shown that a clearance has been produced on the
left side of the units 12a and 12b. The units 12a and 12b can
rotate about the central axis c while following the locus of an
arc. With this rotation, the units 12a and 12b are positioned on a
certain circle even when they are rotated. The center in FIG. 9
illustrates a result obtained by synchronously rotating the units
12a and 12b. The first unit 12a at this moment is positioned in an
upper part of the detector ring 12, whereas the second unit 12b is
positioned in a lower part of the detector ring 12. The right side
in FIG. 9 illustrates a state in which the units 12a and 12b have
been moved to the left side of the detector ring 12. In this state,
the units 12a and 12b are in contact with each other on the left
side, producing a clearance on the right side of the units 12a and
12b.
[0077] 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.
[0078] 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.
[0079] 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.
[0080] 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.
[0081] 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.
[0082] <Introduction of Patient M>
[0083] The following describes a method for introducing the patient
M into the apparatus according to Example 1. FIG. 10 again
illustrates the detector ring 12 illustrated on the right side in
FIG. 9 including the entire apparatus. In the detector ring 12 in
this state, the auxiliary unit 12c has moved relative to the units
12a and 12b and is hidden in back of the detector ring 12 in FIG.
10. The first unit 12a and the second unit 12b are adjacent to each
other while being close to the support member 15 on the left side
of the detector ring 12 and form one C-shaped detector ring 12. On
the right side of the detector ring 12 (the side opposite the
support member 15), a clearance is produced between the first unit
12a and the second unit 12b. This clearance is not covered with the
first guide 13a and the second guide 13b. Consequently, the central
axis c of the detector ring 12 is exposed out of this clearance to
the outside of the apparatus when viewed from the right side in
FIG. 10.
[0084] 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 FIG. 10, a patient couch
42 and a base 41 supporting it are drawn. This patient couch 42 is
formed in a long, narrow shape extending in a direction passing
through the drawing, on which the patient M can be placed. The body
axis direction of the patient M on this patient couch 42 overlaps
with the direction passing through the drawing. Consequently, the
right-and-left direction of FIG. 10 corresponds to the body side
direction of the patient M. Although not illustrated in FIG. 10,
the patient couch 42 and the base 41 are included in the MRI
apparatus. The positional relationship among the MRI apparatus, the
patient couch 42, and the radiation tomography apparatus according
to the present invention is the same as that in FIG. 18. In other
words, the central axis c of the detector ring 12 in FIG. 10
extends in the body axis direction of the patient M.
[0085] 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 FIG. 10
perpendicular to the central axis c of the detector ring 12 and the
vertical direction). When the apparatus is moved close to the
patient M, the patient couch 42 and the patient M positioned
outside the apparatus approach the detector ring 12 from the body
side direction, pass through the clearance of the detector ring 12,
and are introduced inside the detector ring 12. Although the base
41 is drawn as if it collided with the detector ring 12 in FIG. 10,
the actual base 41 is positioned on the near side of the detector
ring 12, and such a collision will not occur.
[0086] FIG. 11 illustrates a state in which the patient M has been
introduced inside the detector ring 12. At this moment, the central
axis c of the detector ring 12 is positioned inside the patient M.
Immediately after the patient M has been introduced, the detector
ring 12 forms a C shape, which resembles the conventional
configuration illustrated in FIG. 18 at first glance. In FIG. 11,
the units 12a and 12b included in the detector ring 12 are drawn
with emphasis by shading. FIG. 12 illustrates the apparatus in the
state in FIG. 11 from a different viewpoint. FIG. 12 shows that the
patient M is stationary inside the C-shaped detector ring 12.
[0087] 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 FIG. 9). With this
rotation, 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 so that,
through the clearance, the patient M is introduced inside the
detector ring 12.
[0088] <Most Characteristic Feature of the Present Invention:
Transformation of Detector Ring 12>
[0089] 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 FIG. 9 is performed, whereby the units 12a and 12b
are rotated so as to be moved to the right side (separated from the
support member 15). Then the clearance positioned on the right side
of the detector ring 12 is moved to the left side. FIG. 13
illustrates the detector ring 12 when this rotational motion ends.
Such rotational motion is performed by the unit rotation mechanisms
33a and 33b. The clearance that has moved to the left side of the
detector ring 12 ensures space just required for the auxiliary unit
12c to enter.
[0090] 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.
[0091] FIG. 14 illustrates a state in which the auxiliary unit 12c
has been moved to the position of the detector ring 12 after the
end of the rotational motion illustrated in FIG. 13. The movement
of the auxiliary unit 12c at this moment is performed by the unit
slide mechanism 32 as illustrated in FIG. 8. Thus, the auxiliary
unit 12c becomes a member included in the detector ring 12, and the
C-shaped detector ring 12 changes to an annular shape. FIG. 15
illustrates the apparatus in the state in FIG. 14 from a different
viewpoint. FIG. 15 reveals that the patient M is stationary inside
the annular-shaped detector ring 12.
[0092] 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.
[0093] 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.
[0094] 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.
[0095] The present invention is not limited to the configuration
described above and can be performed in a modified manner as
follows.
[0096] (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 FIG. 16, the units 12a and 12b themselves can also
rotatably move. In this configuration, a C-shaped guide 13 is
included, and the units 12a and 12b travel along this guide 13,
whereby rotational movement of the units 12a and 12b is performed.
The guide 13 is fixed to the support member 15. Consequently, even
when the units 12a and 12b rotate, the guide 13 does not move
relative to the support member 15.
[0097] 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.
[0098] The present modification can make the apparatus
configuration simpler.
[0099] (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.
[0100] (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.
[0101] (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
[0102] 1 Radiation Detector [0103] 12a First Unit [0104] 12b Second
Unit [0105] 12c Auxiliary Unit [0106] 12 Detector Ring [0107] 15
Support Member [0108] 32 Unit Slide Mechanism (Auxiliary Unit
Mover) [0109] 33a Unit Rotation Mechanism (First Unit Rotator)
[0110] 33b Unit Rotation Mechanism (Second Unit Rotator)
* * * * *