CT scanner comprising a spatially encoded detector array arrangement and method

• US 6,188,745 B1
• Filed: 09/23/1998
• Issued: 02/13/2001
• Est. Priority Date: 09/23/1998
• Status: Expired due to Fees

• Current Assignee: Analogic Corporation
• Original Assignee: Analogic Corporation
• Inventors: Gordon, Bernard M.
• Primary Examiner(s): Porta, David P.
• Application Number:
  US09/159,067
• Time in Patent Office: 874 Days
• Field of Search: 378/4, 378/19, 378/15, 378/147, 378/150
• US Class Current: 378/19
• CPC Class Codes: A61B 6/027 characterised by the use of a particular data acquisition trajectory, e.g. helical or spiral
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4085 Cone-beams
• CPC Class Codes: A61B 6/5205 involving processing of raw data to produce diagnostic data
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]

Abstract

A CT scanner comprising a spatially encoded detector arrangement for providing data values representing variable thickness slices, and a method of efficiently detecting X-rays for variable thickness slices of a CT scanner are disclosed. The spatially encoded detector arrangement includes a plurality of columns of detector elements, with the detector elements of each column being distributed and arranged so that the lengths of at least some of the detector elements of each of the columns vary in accordance with a predetermined sequence code that represents all of the whole integer values in equal increments from 1 to N, wherein N is a whole integer greater than 1, and preferably greater than 3. Preferably, the sequence code is a biquinary code of 5, 2, 2, 1 so that N is at least 10. The detector arrangement is preferably a 2D array having rows of two or more lengths so that beams of various thicknesses each can be projected onto a row or rows of detector elements having a detection area substantially matched to the corresponding beam. The spatial encoding using the sequence code preferably also allows for one or more sets of multiple slices of equal thickness to be simultaneously generated. By spatially encoding the array with the sequence code, the number of detector elements can be reduced from an array made of detector elements of equal length, i.e., the number of detector elements of each column representing the code is less than N, and more efficient X-ray conversion achieved.

Claims

1. A CT scanner system comprising:

a source of X-rays mounted for rotation about a Z-axis; and

a plurality of detector elements arranged in a plurality of columns and positioned relative to the source and one another so that data values representative of CT slices of different thicknesses can be generated in response to X-rays being projected by the source onto corresponding select ones of the detector elements as the source rotates about the Z-axis wherein the detector elements are sized and arranged so that at least some of the detector elements provided in each of the columns have lengths that vary in the Z-axis direction in accordance with a predetermined sequence code that includes the sequence of 5, 2, 2, 1, 1, 2, 2, 5 and represents all of the whole integers in equal incremental values from 1 to at least 10; and

an apertured device for defining a beam of X-rays emanating from the source and directed onto select ones of the detector elements, the apertured device being adjustable in the Z-axis direction so that the thickness of the beam can be controlled so as to generate X-rays from the source only toward the select ones of the detector elements having detection areas substantially matched to the thickness of the corresponding beam.

2. A CT scanner system according to claim 1, wherein the detector elements of each column required to represent the sequence code is less than 10.

3. A CT scanner system according to claim 1, wherein the lengths of the detector elements are sized and arranged in accordance with the predetermined sequence code so that data values representative of at least one set of a plurality of CT slices of equal thicknesses can be simultaneously generated.

4. A CT scanner system according to claim 1, wherein the lengths of the detector elements are sized and arranged in accordance with the predetermined sequence code so that data values representative of any one of a plurality of sets of CT slices can be simultaneously generated, wherein the CT slices within each set are of equal thickness and different from the thickness of the slices within each other set.

5. A CT scanner system according to claim 1, wherein each of the detector elements provides an output as a function of X-rays detected by said detector element, and only the outputs of the corresponding select ones of the detector elements are processed for generating each slice of selected thickness.

6. A CT scanner system according to claim 1, wherein the detector elements are arranged in a 2D array of rows and columns.

7. A method of spatially encoding the detector elements of and using the detector elements in a CT scanner detector arrangement having a plurality of columns of the detector elements oriented in the Z-axis, each column arranged in a predetermined direction and the detector elements being sized and arranged so that data values representative of CT slices of different thicknesses can be generated between a minimum value and a maximum value, comprising:

distributing the detector elements of each column so that the lengths of at least some of the detector elements of each of the columns vary in accordance with a predetermined sequence code that includes 5, 2, 2, 1, 1, 2, 2, 5 and represents all of the whole integer values in equal increments from 1 to at least 10;

adjusting an apertured device for defining a beam of X-rays emanating from the source that are directed to select ones of the detector elements, the apertured device being adjustable in the Z-axis direction so that the thickness of the beam can be controlled so as to generate X-rays from the source only toward the select ones of the detector elements having detection areas substantially matched to the thickness of the corresponding beam.

8. A method according to claim 7, wherein the step of distributing the detector elements includes:

varying the lengths of at least some of the detector elements so that one or more adjacent detectors of each column can be combined to provide the appropriate detection area for the corresponding CT slices of different thicknesses.

9. A method according to claim 7, wherein the step of distributing the defector elements includes:

varying the lengths of at least some of the detector elements so that one or more adjacent detector of each column can be combined to the appropriate detection area for at least a set of adjacent multiple slices of equal thicknesses simultaneously created by projecting a beam onto the detection elements.

10. A method according to claim 7, wherein the step of distributing the detector elements includes:

varying the lengths of at least some of the detector elements so that one or more adjacent detector of each column can be combined to the appropriate detection area for any one of a plurality of sets of adjacent multiple slices simultaneously created by projecting a beam onto the elements, wherein the slices within each set are of equal thickness, and the thickness of the slices of one set differ from the slices of the other sets.