Single photon emission computed tomograph using focused modular collimators

• US 4,748,328 A
• Filed: 07/10/1986
• Issued: 05/31/1988
• Est. Priority Date: 07/10/1986
• Status: Expired due to Term

• Current Assignee: University of Iowa Research Foundation
• Original Assignee: University of Iowa Research Foundation
• Inventors: Rezai, Karim, Chang, Wei, Kirchner, Peter
• Primary Examiner(s): Fields, Carolyn E.
• Application Number:
  US06/884,080
• Time in Patent Office: 691 Days
• Field of Search: 250/505.1, 250/363 SB, 250/363 SC, 250/363 SG, 250/363 SH, 378/10
• US Class Current: 250/363.04
• CPC Class Codes: A61B 6/037 Emission tomography
• CPC Class Codes: G01T 1/2985 In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis); using external radiation sources A61B6/02
• CPC Class Codes: G21K 1/025 using multiple collimators, e.g. Bucky screens; other devices for eliminating undesired or dispersed radiation

Abstract

A single photon emission computed tomograph comprising a detector ring and a rotatable collimator assembly disposed within the detector ring. The rotatable collimator assembly comprises four collimator quadrants, and each of the four collimator quadrants comprises a plurality of collimator modules with their axes assembled in parallel. Each of the modules contains a plurality of inwardly directed channels focused to a single point on its own axis with a long focal length. The focal length of each of the collimator modules is individually and flexibly chosen to suit a particular imaging task. The four collimator quadrants are installed in the rotatable collimator assembly at a slightly different angular offset so as to achieve fine data sampling.

Claims

1. A single photon emission computed tomograph comprising:

(a) a detector ring and

(b) a rotatable collimator assembly disposed within said detector ring, said rotatable collimator assembly comprising four collimator quadrants, each of said four collimator quadrants comprising a plurality of collimator modules with their axes assembled in parallel, each of said modules containing a plurality of inwardly directed channels focused to a single point on its own axis, the focal length of each of said collimator modules being individually chosen to suit a particular imaging task,

(c) wherein each of said four collimator quardants is installed in said rotatable collimator assembly at a slightly different first angular offset to achieve fine data sampling, the first angular offsets being in the range of just greater than 0°

to the angle subtended by each discrete crystal in said detector ring.

2. A single photon emission computed tomograph as recited in claim 1 wherein said first angular offset of each of said four quadrant ring collimators is in the range of 1.0°

to 2.0°

.

3. A single photon emission computed tomograph as recited in claim 1 wherein each of said four collimator quadrants is installed at a second angular offset on the order of 1/4 of said first angular offset to achieve quarter ray offset in data sampling.

4. A single photon emission computed tomograph as recited in claim 1 and further comprising a lead wedge disposed between each two adjacent ones of said collimator quadrants.