Collimator for detector and application thereof
A collimator for a detector is disclosed. The collimator comprises: a bottom plate provided with imaging through holes distributed in an array, each of the imaging through holes comprising a first hole segment and a second hole segment, the transverse size of the first hole segment gradually decreasing in a direction from a free end to the second hole segment, and the transverse size of the second hole segment gradually decreasing in a direction from the free end to the first hole segment; a shielding case formed on the bottom plate; and a top plate disposed in the shielding case and closing at least a part of an opening of the shielding case, the top plate being provided with shielding through holes distributed in an array, and the imaging through holes being in one-to-one correspondence with the shielding through holes.
1. A collimator for a detector, comprising:
a bottom plate provided with imaging through holes distributed in an array, wherein the imaging through hole comprises a first hole segment and a second hole segment, wherein a transverse size of the first hole segment gradually decreases from a free end to the second hole segment, and a transverse size of the second hole segment gradually decreases from a free end to the first hole segment;
a shielding case formed on the bottom plate and blocking light from entering the collimator from the external environment;
a top plate arranged in the shielding case and closing at least a part of an opening of the shielding case, wherein the top plate is provided with shielding through holes distributed in an array, and the imaging through holes and the shielding through holes are arranged in one-to-one correspondence; and
a supporting member arranged between the top plate and the bottom plate and configured to support and fix the top plate and the bottom plate,
wherein the shielding case surrounds the bottom plate and the top plate, and a periphery of the top plate is within the shielding case.
2. The collimator according to claim 1 , wherein the first hole segment and the second hole segment are symmetrically arranged in an up-down direction.
3. The collimator according to claim 1 , wherein the first hole segment and the second hole segment are independently configured into a truncated cone or a truncated polygonal pyramid.
4. The collimator according to claim 1 , wherein the shielding through hole is a straight hole or an oblique hole.
5. The collimator according to claim 1 , wherein a lower edge of the shielding through hole coincides with an intersection line between an extension surface of a peripheral surface where an inner wall of the first hole segment is located and a lower surface of the top plate.
6. The collimator according to claim 1 , wherein the collimator has a light-shielding rate of less than 10%, wherein the light-shielding rate is determined by the formula:
Light
‐
shielding
rate
=
S
1
S
2
=
(
H
tan
α
2
+
HD
T
-
D
2
H
tan
α
2
+
D
2
)
2
-
1
in which:
S 1 represents a projected area of a penumbra region of the collimator;
S 2 represents a projected area of an umbra region of the collimator;
H represents a distance from a center of the imaging through hole to a surface of the detector;
α represents an included angle from a midpoint of a connecting surface of the first hole segment and the second hole segment to the free end of the first hole segment;
D represents a maximum diameter of the imaging through hole;
T represents a distance from a bottom surface of the bottom plate to a top surface of the top plate.
7. The collimator according to claim 1 , wherein a thickness of the top plate and a thickness of the bottom plate are not less than 3.5 mm.
8. The collimator according to claim 1 , wherein a thickness of the bottom plate is 10 mm to 14 mm, and a thickness of the top plate is 2 mm to 6 mm.
9. The collimator according to claim 1 , wherein a diameter of the shielding through hole is 3 mm to 6 mm.
10. The collimator according to claim 1 , wherein a diameter of the shielding through hole is 4.5 mm.
11. A detector, comprising a collimator, wherein the collimator comprises:
a bottom plate provided with imaging through holes distributed in an array, wherein the imaging through hole comprises a first hole segment and a second hole segment, wherein a transverse size of the first hole segment gradually decreases from a free end to the second hole segment, and a transverse size of the second hole segment gradually decreases from a free end to the first hole segment;
a shielding case formed on the bottom plate and blocking light from entering the collimator from the external environment;
a top plate arranged in the shielding case and closing at least a part of an opening of the shielding case, wherein the top plate is provided with shielding through holes distributed in an array, and the imaging through holes and the shielding through holes are arranged in one-to-one correspondence; and
a supporting member arranged between the top plate and the bottom plate and configured to support and fix the top plate and the bottom plate,
wherein the shielding case surrounds the bottom plate and the top plate, and a periphery of the top plate is within the shielding case.
12. The detector according to claim 11 , wherein the detector is a variable-angle dual-detector single photon emission computed tomography imaging device.
13. The detector according to claim 11 , wherein orientations of different imaging through holes point to different directions and converge in a center of an imaging field of view.
14. The detector according to claim 11 , wherein the first hole segment and the second hole segment are symmetrically arranged in an up-down direction.
15. The detector according to claim 11 , wherein the first hole segment and the second hole segment are independently configured into a truncated cone or a truncated polygonal pyramid.
16. The detector according to claim 11 , wherein the shielding through hole is a straight hole or an oblique hole.
17. The detector according to claim 11 , wherein a lower edge of the shielding through hole coincides with an intersection line between an extension surface of a peripheral surface where an inner wall of the first hole segment is located and a lower surface of the top plate.
18. The detector according to claim 11 , wherein the collimator has a light-shielding rate of less than 10%, wherein the light-shielding rate is determined by the formula:
Light
‐
shielding
rate
=
S
1
S
2
=
(
H
tan
α
2
+
HD
T
-
D
2
H
tan
α
2
+
D
2
)
2
-
1
in which:
S 1 represents a projected area of a penumbra region of the collimator;
S 2 represents a projected area of an umbra region of the collimator;
H represents a distance from a center of the imaging through hole to a surface of the detector;
α represents an included angle from a midpoint of a connecting surface of the first hole segment and the second hole segment to the free end of the first hole segment;
D represents a maximum diameter of the imaging through hole;
T represents a distance from a bottom surface of the bottom plate to a top surface of the top plate.
19. The detector according to claim 11 , wherein the bottom plate, the top plate, the shielding case, and the supporting member may be made of at least one of gold, tantalum, platinum, tungsten, and lead.