Scanning method

Patent metadata

Field	Value
Publication number	US-9869647-B2
Application number	US-201415103009-A
Country	US
Kind code	B2
Filing date	Dec 18, 2014
Priority date	Dec 23, 2013
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

A scanning method which is a method of identifying a change in the density of an object includes arranging a source of ionizing radiation and an array of radiation detectors Dn, where n is an integer from 1 to N, capable of detecting the radiation in such a way that radiation counts are counted by the detectors as the source and detectors are rotated around the object and normalized counts values are collated in a matrix such that a pattern may be detected within the matrix from which the presence of a change in the density of the object at a location lying on at least one of the radiation paths may be inferred.

First claim

The invention claimed is:

1. A scanning method which is a method of identifying a change in the density of a pipeline located underwater, said change representing a difference between the density of said pipeline at a first location and the density of said pipeline at a second location adjacent said first location, the method comprising the steps of:
a. arranging a source of ionizing radiation and an array of N radiation detectors Dn,
where n is an integer from 1 to N, capable of detecting said radiation in such a way
that
i. radiation is emitted from the source in the direction of the array of radiation detectors,
ii. radiation is emitted from the source towards any one of said radiation detectors along a radiation path, said radiation path being defined at each end by the source and the area of each detector facing said source;
iii. up to N of said radiation paths may pass through said pipeline; and
iv. said source and said detector array are located in fixed positions relative to one another and movable along an arcuate scanning path around said pipeline;

b. positioning the source and detector array at a known, position p0 on said scanning path;
c. acquiring count data Cnx from each detector Dn, for n=1 to N, for a predetermined period of time, said count data being related to the number of photons of radiation emitted by the source which have been detected by said detector during the predetermined period of time;
d. repeating steps b and c at a plurality of different positions px on the scanning path, where x is an integer from 1 to X;
e. optionally adjusting each Cnx according to a calibration;
f. optionally converting each Cnx by means of a fan to parallel beam conversion algorithm to a converted Cnx;
g. for each detector Dn, calculating normalised Cnx values for each Cnx for n=1 to N and for x=1 to X,
h. collating each normalised Cnx value in a matrix with rows and columns corresponding to n and x;
i. analyzing the matrix to detect a pattern within the matrix of normalised Cnx values which are higher or lower than the mean counts value; and
inferring from said pattern the presence of a change in the density of said pipeline at a location lying on at least one of said radiation paths.

2. A scanning method according to claim 1 , wherein said matrix of normalised count data is displayed to an operator.

3. A scanning method according to claim 2 , wherein the normalised count data is represented in the matrix in the form of symbols.

4. A scanning method according to claim 3 , wherein the symbols take the form of coloured dots, pixels or blocks where each colour represents a selected range of normalised count data.

5. A scanning method according to claim 1 , wherein the matrix of count data is analysed by pattern recognition algorithms using data processing software.

6. A scanning method according to claim 1 , wherein a tomographic image is constructed from the count data obtained from the detectors.

7. A scanning method according to claim 1 , wherein the detection of a pattern in the matrix causes additional count data to be acquired.

8. A scanning method according to claim 1 , wherein the pipeline, or a portion thereof, lies wholly within the scanning path.

9. A scanning method according to claim 1 , wherein positions x are equally angularly spaced.

10. A scanning method according to claim 1 , wherein X lies between 180 and 1450.

11. A scanning method according to claim 1 , wherein data is acquired from the detectors as the source and detector move along the scanning path.

12. A scanning method according to claim 1 , wherein data is acquired from the detectors continually and recorded together with a record of the position at which the data was acquired.

13. A scanning method according to claim 11 , wherein the positions of data collection are banded into a series of angular intervals related to the start position p0.

14. A scanning apparatus for identifying a change in the density of a pipeline located underwater, the scanning apparatus comprising a source of ionizing radiation, an array of N radiation detectors Dn, where n is an integer from 1 to N, capable of detecting said radiation, said source and detector array being arranged in such a way that
i. radiation is emitted from the source in the direction of the array of radiation detectors,
ii. radiation is emitted from the source towards any one of said radiation detectors along a radiation path, said radiation path being defined at each end by the source and the area of each detector facing said source;
iii. up to N of said radiation paths may pass through pipeline which is to be scanned; and
iv. said source and said detector array are located in fixed positions relative to one another and movable along an arcuate scanning path around said pipeline;
means to position the source and detector array at a number of known, positions on said scanning path; data processing means which is programmed to
a. acquire count data Cnx from each detector Dn, for n=1 to N, for a predetermined period of time, said count data being related to the number of

photons of radiation emitted by the source which have been detected by said detector during the predetermined period of time at a plurality of different positions px on the scanning path, where x is an integer from 1 to X;
b. optionally adjust each Cnx according to a calibration;
c. optionally convert each Cnx by means of a fan to parallel beam conversion algorithm to a converted Cnx;
for each detector Dn,
d. calculate normalised Cnx values for each Cnx for n=1 to N and for x=1 to X;
e. collate each normalised Cnx value in a matrix with rows and columns corresponding to n and x; and
analyze the matrix to detect a pattern within the matrix of normalized Cnx values which are higher or lower than a mean counts value.

Assignees

• Johnson Matthey Plc

Inventors

• Featonby Paul David
• Ronchi Emanuele

Classifications

• G01N2223/419

  computed tomograph · CPC title

• G01N2223/202

  isotopes · CPC title

• G01N2223/1013

  gamma · CPC title

• G01N2223/501

  array · CPC title

• G01N2223/628

  tubes, pipes · CPC title