EP0692708A2 — Imaging method for spatial distributions of absor…

Claim 1

Independent Claim 198 words

An imaging method for spatial distributions of concentrations of absorbers distributed in an object comprising: a radiation step of applying pulsating or continuous lights radiated from predetermined incident positions with predetermined wavelengths to said object comprising a scattering medium containing said absorbers; and a detection step of detecting intensities of lights passing through said object at predetermined detection positions, said imaging method further comprising the steps of: assuming an imaginary object having a shape identical with or similar to that of said object and containing no absorbers and, for each of a plurality of pairs of incident and detection positions set on said imaginary object, finding a plurality of photon paths starting at said incident position and ending at said detection position; finding averaged photon-path lengths of said photon paths starting at said incident positions and ending at said detection positions in said imaginary object; finding spatial distributions of absorber concentrations from said averaged photon-path lengths, radiated intensities of said radiated lights applied to said object, detected intensities of lights detected at said detection positions and optical constants of said absorbers for said radiated lights applied to said object; and displaying said spatial distributions of said absorber concentrations.

Claim 2

Dependent Claim 79 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 1 comprising the steps of: creating a measurement matrix representing a ratio of said radiated intensity to said detected intensity for one of said pairs; creating a matrix expressing a spatial distribution of averaged photon-path lengths representing said averaged photon-path length for one of said pairs; and finding said absorber concentrations from said measurement matrix and said matrix expressing a spatial distribution of averaged photon-path lengths.

Claim 3

Dependent Claim 86 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 1 wherein said object has a predetermined shape and a predetermined scattering coefficient, said imaging method comprising the steps of: creating a matrix expressing a spatial distribution of averaged photon-path lengths representing said averaged photon-path length for one of said pairs; and storing said matrix expressing a spatial distribution of averaged photon-path lengths created at the step of creating said matrix expressing a spatial distribution of averaged photon-path lengths in a storage means.

Claim 4

Dependent Claim 76 words

An imaging method for spatial distributions of absorber concentrations according to Claim 3 wherein said object has a predetermined shape and a predetermined scattering coefficient, said imaging method comprising the steps of: creating a measurement matrix representing a ratio of said radiated intensity to said detected intensity for one of said pairs; and finding absorber concentrations from said measurement matrix and said matrix expressing a spatial distribution of averaged photon-path lengths stored in said storage means.

Claim 5

Dependent Claim 94 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 1 wherein said object has a predetermined shape and a predetermined scattering coefficient, said imaging method comprising the steps of: creating a measurement matrix representing a ratio of said radiated intensity to said detected intensity for one of said pairs; creating a matrix expressing a spatial distribution of averaged photon-path lengths representing said averaged photon-path length for one of said pairs; and finding said absorber concentrations from said measurement matrix and said matrix expressing a spatial distribution of averaged photon-path lengths.

Claim 6

Dependent Claim 87 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 1 having the step of carrying out coordinate transformation for finding data of said photon paths for a pair (j - i) from data of said photon paths for a pair (i - j) where said pair (i - j) comprises said incident position (i) and said detection position (j) and said pair (j - i) is obtained by swapping locations of said incident position (i) and said detection position (j) for each other.

Claim 7

Dependent Claim 122 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 1 comprising the step of simulating said step of finding a plurality of photon paths by means of a Monte Carlo method using a random number and a function expressing scattering-angle dependence relating a spatial coordinate position of a current scattering point to that of a next scattering point among a plurality of points scattering a photon from a point to another and wherein said Monte Carlo method is used for simulating a photon path traced by said photon originating from a point in an imaginary scattering medium having virtually the same scattering coefficient as that of said object and a size large enough to contain said imaginary object.

Claim 8

Dependent Claim 139 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 1 comprising the steps of: simulating said step of finding a plurality of photon paths by means of a Monte Carlo method using a random number and a function expressing scattering-angle dependence relating a spatial coordinate position of a current scattering point to that of a next scattering point among a plurality of points scattering a photon from one point to another wherein said Monte Carlo method is used for simulating a photon path traced by said photon originating from a point in an imaginary scattering medium having virtually the same scattering coefficient as that of said object and a size large enough to contain said imaginary object; and storing spatial coordinate positions of said scattering points in memory which scattering points express said photon paths.

Claim 9

Dependent Claim 53 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 1 wherein lights radiated to said object at said radiation step have a plurality of wavelengths ranging from 400 nm to 2,000 nm and differences in value between any two of said wavelengths are all made smaller than 100 nm.

Claim 10

Dependent Claim 46 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 1 wherein the number of lights radiated to said object at said radiation step is greater by unity than the number of absorbers and said radiated lights have wavelengths different from each other.

Claim 11

Dependent Claim 36 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 1 wherein said optical constants are absorption coefficients of said absorbers for wavelengths of lights radiated to said object at said radiation step.

Claim 12

Dependent Claim 244 words

An imaging method for spatial distributions of concentrations of absorbers distributed in an object comprising: a radiation step of applying pulsating or continuous lights radiated from predetermined incident positions with predetermined wavelengths to said object comprising a scattering medium containing said absorbers; and a detection step of detecting intensities of lights passing through said object at predetermined detection positions; said imaging method further comprising the steps of: assuming an imaginary object having a shape identical with or similar to that of said object and containing no absorbers and, for each of a plurality of pairs of incident and detection positions set on said imaginary object, finding a plurality of photon paths starting at said incident position and ending at said detection position; finding averaged photon-path lengths of said photon paths starting at said incident positions and ending at said detection positions in said imaginary object; finding spatial distributions of absorber concentrations from said averaged photon-path lengths, radiated intensities of said radiated lights applied to said object, detected intensities of lights detected at said detection positions and optical constants of said absorbers for said radiated lights applied to said object; and displaying said spatial distributions of said absorber concentrations, wherein at said step of finding said photon paths, each of said photon paths traced by a photon emitted from a predetermined point in an imaginary scattering medium having virtually the same scattering coefficient as that of said object is simulated by a Monte Carlo method.

Claim 13

Dependent Claim 33 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 12 whereby spatial distributions of concentrations of said absorbers each emitting a single photon from said predetermined point are found.

Claim 14

Dependent Claim 66 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 12 wherein said imaginary scattering medium is a sphere having a radius equal to or greater than a maximum distance from any arbitrary point to another arbitrary one in said imaginary object and said predetermined point is set at the center of said sphere, from which point a plurality of photons are emitted.

Claim 15

Dependent Claim 96 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 12 wherein: said incident position in said object is made coincide with a point in said imaginary scattering medium; transformation is carried out on either spatial coordinates of said scattering points representing said photon paths or spatial coordinates expressing the shape of said imaginary object in such a way that said detection position in said imaginary object is crossed; and photon paths starting from said incident positions in said imaginary object and ending at said detection positions in said imaginary object are found.

Claim 16

Dependent Claim 258 words

An imaging method for spatial distributions of concentrations of absorbers distributed in an object comprising: a radiation step of applying pulsating or continuous lights radiated from predetermined incident positions with predetermined wavelengths to said object comprising a scattering medium containing said absorbers; and a detection step of detecting intensities of lights passing through said object at predetermined detection positions; said imaging method further comprising the steps of: assuming an imaginary object having a shape identical with or similar to that of said object and containing no absorbers and, for each of a plurality of pairs of incident and detection positions set on said imaginary object, finding a plurality of photon paths traced by photons starting at said incident position and ending at said detection position; finding averaged photon-path lengths of said photon paths starting at said incident positions and ending at said detection positions in said imaginary object; finding spatial distributions of absorber concentrations from said averaged photon-path lengths, radiated intensities of said radiated lights applied to said object, detected intensities of lights detected at said detection positions and optical constants of said absorbers for said radiated lights applied to said object; and displaying said spatial distributions of said concentrations of said absorbers, wherein a space expressing the shape of said object is divided into a plurality of volume elements, in each of which, said averaged photon-path length is found and, by assuming that concentrations of said absorbers in each of said volume elements are uniform, concentrations of said absorbers in each of said volume elements are found.

Claim 17

Dependent Claim 37 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 16 wherein the number of pairs of said incident positions and said detection positions is greater than the total number of said volume elements.

Claim 18

Dependent Claim 127 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 16 wherein a space expressing the shape of said imaginary object is divided into a plurality of volume elements in the same way as said space expressing the shape of said object is divided into a plurality of volume elements and said imaging method further comprises the step of finding said photon paths in said imaginary object between said volume elements having said incident positions set therein and said volume elements having said detection positions set therein by means of a Monte Carlo method using a scattering coefficient of said object and parameters representing scattering-angle dependence of photon scattering in said object for each of said various pairs of said incident and detection positions.

Claim 19

Dependent Claim 150 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 16 wherein a space expressing the shape of said imaginary object is divided into a plurality of volume elements in the same way as said space expressing the shape of said object is divided into a plurality of volume elements and said imaging method further comprises the steps of: finding said photon paths in said imaginary object between said volume elements having said incident positions set therein and said volume elements having said detection positions set therein by means of a Monte Carlo method using a scattering coefficient of said object and parameters representing scattering-angle dependence of photon scattering in said object for each of said various pairs of said incident and detection positions; and finding an averaged photon-path length for each of said volume elements by averaging lengths of photon paths in each of said pairs.

Claim 20

Dependent Claim 175 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 16 wherein a space expressing the shape of said imaginary object is divided into a plurality of volume elements in the same way as said space expressing the shape of said object is divided into a plurality of volume elements and said imaging method further comprises: a step of finding said photon paths in said imaginary object between said volume elements having said incident positions set therein and said volume elements having said detection positions set therein by means of a Monte Carlo method using a scattering coefficient of said object and parameters representing scattering-angle dependence of photon scattering in said object for each of said various pairs of said incident and detection positions; and a shape measuring step of measuring the external shape of said object to give measurement data used as a base for providing coordinate data representing a space of the shape of said imaginary object or coordinate data representing a space of a shape resembling said imaginary object.

Claim 21

Dependent Claim 189 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 16 wherein a space expressing the shape of said imaginary object is divided into a plurality of volume elements in the same way as said space expressing the shape of said object is divided into a plurality of volume elements and said imaging method further comprises the steps of: creating a measurement matrix each representing a ratio of said radiated intensity to said detected intensity; finding said photon paths in said imaginary object between said volume elements having said incident positions set therein and said volume elements having said detection positions set therein by means of a Monte Carlo method using a scattering coefficient of said object and parameters representing scattering-angle dependence of photon scattering in said object for each of said various pairs of said incident and detection positions; and creating a matrix expressing a spatial distribution of averaged photon-path lengths representing said averaged photon path lengths for said pairs found from said photon paths, wherein absorber concentrations are found from said measurement matrix and said matrix expressing a spatial distribution of averaged photon-path lengths.

Claim 22

Dependent Claim 34 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 21 further comprising the step of storing said matrix expressing a spatial distribution of averaged photon-path lengths in a storage means.

Claim 23

Dependent Claim 145 words

An imaging method for spatial distributions of concentrations of absorbers according to Claim 16 further comprising the steps of: creating a measurement matrix each representing a ratio of said radiated intensity to an integrated detected intensity for one of said pairs wherein said integrated detected intensity is obtained by measuring the intensity of a light passing through said object by using a time-resolving technique at said detection step and integrating results of measuring the intensity of said light by using said time-resolving technique over a predetermined period of time; creating a matrix expressing a spatial distribution of averaged photon-path lengths representing said averaged photon path lengths for said pairs found from photon paths for said photons arriving at said detection positions from said incident positions, wherein absorber concentrations are found from said measurement matrix and said matrix expressing a spatial distribution of averaged photon-path lengths.

Claim 24

Dependent Claim 204 words

An imaging method for spatial distributions of concentrations of absorbers comprising: a radiation step of applying pulsating or continuous lights radiated from predetermined incident positions to an object; a detection step of detecting intensities of lights passing through said object at predetermined detection positions; and a step of calculating concentrations of said absorbers distributed in said object from said intensities detected at said detection step, said imaging method further comprising the steps of: setting an imaginary scattering medium having a size containing said object and virtually the same scattering coefficient as that of said object and containing no absorbers and finding first photon paths traced by photons originating from a predetermined position in said imaginary scattering medium by simulation using a Monte Carlo method; and finding second photon paths passing through said incident positions and said detection positions from data for said first photon paths, wherein spatial distributions of concentrations of said absorbers are found from data for said second photon paths passing through said incident positions and said detection positions, radiated intensities of said radiated lights applied to said object, detected intensities of lights detected at said detection positions and spectral constants of said absorbers for said radiated lights applied to said object.

Claim 25

Dependent Claim 208 words

An imaging method for spatial distributions of concentrations of absorbers comprising: a radiation step of applying pulsating or continuous lights radiated from predetermined incident positions to an object; a detection step of detecting intensities of lights passing through said object at predetermined detection positions; and a step of calculating concentrations of said absorbers distributed in said object from said intensities detected at said detection step, said imaging method further comprising the step of setting an imaginary scattering medium having a size containing said object and virtually the same scattering coefficient as that of said object and containing no absorbers, finding first photon paths traced by photons originating from a predetermined position in said imaginary scattering medium by simulation using a Monte Carlo method in advance to be stored as photon-path data, and finding second photon paths passing through said incident positions and said detection positions from said photon-path data, wherein spatial distributions of concentrations of said absorbers are found from data for said second photon paths passing through said incident positions and said detection positions, radiated intensities of said radiated lights applied to said object, detected intensities of lights detected at said detection positions and spectral constants of said absorbers for said radiated lights applied to said object.

Claim 26

Dependent Claim 277 words

An imaging method for spatial distributions of concentrations of absorbers distributed in an object comprising: a radiation step of applying pulsating or continuous lights radiated from predetermined incident positions with predetermined wavelengths to said object comprising a scattering medium containing said absorbers; and a detection step of detecting intensities of lights passing through said object at predetermined detection positions; said imaging method further comprising the steps of: dividing a space expressing the shape of said object into a plurality of first volume elements, assuming an imaginary object having a shape identical with or similar to that of said object and containing no absorbers, dividing a space expressing the shape of said imaginary object into a plurality of second volume elements in the same way as said space expressing the shape of said object is divided into said first volume elements and, for each of a plurality of pairs of incident and detection positions set on said imaginary object, finding a plurality of photon paths traced by photons starting at said incident position and ending at said detection position by simulation using the Monte Carlo method; finding averaged photon-path lengths of said photon paths starting at said incident positions and ending at said detection positions for each of said second volume elements in said imaginary object; finding spatial distributions of absorber concentrations for each of said second volume elements from said averaged photon-path lengths, radiated intensities of said radiated lights applied to said object, detected intensities of lights detected at said detection positions and optical constants of said absorbers for said radiated lights applied to said object; and displaying said spatial distributions of said concentrations of said absorbers.

Claim 27

Dependent Claim 290 words

An imaging method for spatial distributions of concentrations of absorbers distributed in an object comprising: a radiation step of applying pulsating or continuous lights radiated from predetermined incident positions with predetermined wavelengths to said object comprising a scattering medium containing absorbers; and a detection step of detecting intensities of lights passing through said object at predetermined detection positions; said imaging method further comprising the steps of: dividing a space expressing the shape of said object into a plurality of first volume elements, assuming an imaginary object having a shape identical with or similar to that of said object and containing no absorbers, dividing a space expressing the shape of said imaginary object into a plurality of second volume elements in the same as said space expressing the shape of said object is divided into said first volume elements and, for each of a plurality of pairs of incident and detection positions set on said imaginary object, finding a plurality of photon paths traced by photons starting at said incident position and ending at said detection position by simulation using the Monte Carlo method in advance to be stored in memory as photon-path data, and finding averaged photon-path lengths of said photon paths starting at said incident positions and ending at said detection positions for each of said second volume elements in said imaginary object from said photon-path data; finding spatial distributions of absorber concentrations for each of said second volume elements from said averaged photon-path lengths, radiated intensities of said radiated lights applied to said object, detected intensities of lights detected at said detection positions and optical constants of said absorbers for said radiated lights applied to said object; and displaying said spatial distributions of said concentrations of said absorbers.

Claim 28

Dependent Claim 134 words

An imaging method for spatial distributions of concentrations of absorbers comprising: a radiation step of applying pulsating or continuous lights radiated from predetermined incident positions to an object; a detection step of detecting intensities of lights passing through said object at predetermined detection positions; and a step of calculating concentrations of said absorbers distributed in said object from said intensities detected at said detection step, said imaging method further comprising the steps of: finding photon-path data representing photon paths passing through said incident positions and said detection positions; and finding spatial distributions of concentrations of said absorbers from said photon-path data, radiated intensities of said radiated lights applied to said object, detected intensities of lights detected at said detection positions and spectral constants of said absorbers for said radiated lights applied to said object.

Claim 29

Dependent Claim 143 words

An imaging method for spatial distributions of concentrations of absorbers distributed in an object comprising: a radiation step of applying pulsating or continuous lights radiated from predetermined incident positions at predetermined wavelengths to said object comprising a light scattering medium containing said absorbers; and a detection step of detecting intensities of lights passing through said object at predetermined detection positions, said imaging method further comprising the steps of: finding a plurality photon paths starting at said incident positions and ending at said detection positions; finding averaged photon-path lengths from said photon paths; and finding spatial distributions of concentrations of said absorbers for each volume element from said averaged photon-path lengths, radiated intensities of said radiated lights applied to said object, detected intensities of lights detected at said detection positions and optical constants of said absorbers for said radiated lights applied to said object.

Imaging method for spatial distributions of absorber concentrations

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