Scanning method
AssigneeJohnson Matthey Public Limited Company
InventorsPaul David Featonby, Emanuele Ronchi
Life of this patent
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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.
Claims14
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.
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.
Dependencies are inferred from the claim text.