Pet device

• US 20030189174A1
• Filed: 02/27/2003
• Published: 10/09/2003
• Est. Priority Date: 08/30/2000
• Status: Active Grant

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Okada, Hiroyuki, Tanaka, Eiichi, Yamashita, Takaji
• Granted Patent: US 7,038,210 B2
• Time in Patent Office: Days
• US Class Current: 250/363.03
• CPC Class Codes: G21K 1/025 using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation

Abstract

A rotating ceptor 20 provided inside a detector portion 10 includes nine shield plates S₁ to S₉ disposed in parallel to each other in between adjacent detector rings R, acts as a collimator, and allows only those photon pairs that have traveled approximately parallel to a slice plane to be made incident upon photon detectors D located behind the rotating ceptor 20. Each of the shield plates S is not formed annularly, and provided near the measurement field of view 1 of part of N photon detectors D that constitute each of the detector rings R. The rotating ceptor 20 is rotatable about its center axis. Each of the shield plates S is provided with bar-shaped radiation source insertion holes 20a and 20b for allowing a bar-shaped positron emission radiation source 3 to be inserted therein and supported thereby.

Claims

1. A PET device comprising

a detector portion having multiple detector rings on which multiple photon detectors each for detecting photons traveling from a measurement field of view containing a center axis are disposed on said slice plane perpendicular to said center axis, said multiple detector rings being stacked in layers in a direction parallel to said center axis,

a rotating ceptor disposed rotatably about said center axis near said measurement field of view of part of said multiple photon detectors which constitute each of said multiple sets of detector rings, said rotating ceptor including multiple shield plates for collimating and passing therethrough only those photons that have traveled approximately parallel to said slice plane,

radiation source support means for detachably supporting a calibration positron emission radiation source at a position at which photons produced by positrons emitted from the positron emission radiation source are collimated by said rotating ceptor in all directions parallel to said slice plane,

rotating ceptor position determination means for determining whether said rotating ceptor is present near said measurement field of view of at least one of a pair of photon detectors when the pair of photon detectors of the photon detectors included in said detector portion simultaneously counts photon pairs,

two-dimensional projection data accumulating means for accumulating simultaneous count information on photon pairs detected by said pair of photon detectors when said rotating ceptor position determination means has determined that said rotating ceptor is present near said measurement field of view of at least one of said pair of photon detectors,

three-dimensional projection data accumulating means for accumulating simultaneous count information on photon pairs detected by said pair of photon detectors when said rotating ceptor position determination means has determined that said rotating ceptor is not present near any one of said measurement fields of view of said pair of photon detectors, and

image reconstruction means for reconstructing an image representing a spatial distribution of frequencies of occurrence of photon pairs in said measurement field of view in accordance with the two-dimensional projection data produced by accumulating simultaneous count information by means of said two-dimensional projection data accumulating means and the three-dimensional projection data produced by accumulating simultaneous count information by means of said three-dimensional projection data accumulating means.

2. The PET device according to claim 1, wherein

a blocking plate for blocking photons produced by positrons emitted from a positron emission radiation source supported by said radiation source support means is provided on a side of said rotating ceptor.

3. The PET device according to claim 1, further comprising

rotating ceptor retract means for disposing said rotating ceptor in said measurement field of view and

for retracting said rotating ceptor from said measurement field of view.