Imaging apparatus and methods

Claim 2

A method according to Claim 1 wherein the interpolating step includes interpolating with a cubic weighting function (66).

Claim 3

A method according to Claim 1 wherein the interpolating step includes interpolating with an n-lobe helical weighting function (70), where n is greater than or equal to 3.

Claim 4

A method according to Claim 3 wherein views taken at more than four longitudinal positions are interpolated with the n-lobe helical weighting function (70).

Claim 12

A method according to Claim 11 wherein each view represents a plurality of rays of radiation extending in a fan-shaped pattern from an apex (28), each ray being identifiable by an angular position (φ, ϑ) of the view around the spiral and by an angle of the ray (β,α) within the view; and, wherein the interpolating step includes interpolating the rays within each view with an interpolating function (82, 84, 86, 88) selected in accordance with both the view angular position (φ, ϑ) and the ray angle (β,α).

Claim 13

A method according to Claim 11 or 12 wherein adjacent groups of views are generated with different energy radiation.

Claim 14

A method according to Claim 11, 12 or 13 further including: monitoring cyclic movement of regions of the subject; and, synchronizing relative rotational movement between the regions of the subject and the radiation source (12) with the cyclic movement of said regions.

Claim 15

A method according to Claim 11, 12, 13 or 14 wherein the interpolation function has a higher band width at selected view angular positions and a smaller band width at other selected view angular positions.

Claim 16

A method according to Claim 11, 12, 13, 14 or 15 further including the step of moving the subject and radiation source (12) to irradiate the subject along a second spiral path different from the first but covering the same volume.

Claim 17

A method according to Claim 11, 12, 13, 14, 15 or 16 wherein the view collecting step includes collecting radiation from the source (12) which has traversed the sample with at least two arcs of radiation detectors (24), which arcs are displaced longitudinally.

Claim 19

A method according to Claim 18 wherein the reconstructing step includes reconstructing groups of views which span about 180° of each planar image representation.

Claim 21

A method of imaging as claimed in Claim 20 comprising: causing relative rotational and longitudinal movement between said subject and said source of radiation (12) such that the subject is irradiated along a generally spiral path.

Claim 22

A method according to Claim 20 or 21 further including operating on a plurality of views, each with a corresponding view angular position (φ, ϑ) with an interpolation function to create an interpolated view, and wherein the reconstructing step is performed on the interpolated views.

Claim 23

A method according to Claim 20, 21, 22 or 23 further including varying an energy output of the source of radiation (12) between at least two levels.

Claim 24

A method according to Claim 21 wherein the reconstructing step includes reconstructing a plurality of views collected over other than two revolutions around the spiral.

Claim 27

A method according to Claim 26 wherein each data view is defined by a plurality of rays in a fan shaped array and wherein in the filtering step, a filtering function (82, 84, 86, 88, 116, 118) is weighted in accordance with an angle of the view (φ, ϑ) around the subject and an angle of the ray (β,α) within each view.

Claim 28

A method according to Claim 26 or 27 wherein in the irradiating step, the energy of the radiation source beam is varied between at least two energy levels.

Claim 30

A method according to claim 29 further including means (32) for advancing the subject through the examination region (14) with a substantially constant velocity.

Claim 31

A method according to claim 29 or 30 further including varying the filter function (62, 66, 68, 70, 82, 84, 86, 88, 94, 98, 116, 118) in accordance with at least one of the view angle (φ, ϑ) and the ray angle (β,α).

Claim 32

A method according to claim 29, 30 or 31 wherein in the radiation detecting step, views of data are collected which lie along at least two spiral paths around a common imaged volume of the subject.

Claim 33

A method according to claim 30, 31 or 32 wherein the reconstructing step includes reconstructing a plurality of views which span less than 360° around the spiral.

Claim 34

A method according to claim 29, 30, 31, 32 or 33 further including monitoring an angular position (φ) of the radiation source (12) around the examination region and wherein the energy of the radiation source (12) is varied in accordance with the monitored angular position (φ) of the radiation source (12).

Claim 36

An imaging apparatus including: means (20, 32) for moving a radiation source (12) and a subject relative to each other so as to irradiate the subject along a generally spiral path; and an arc of radiation detectors (24) for receiving radiation which has traversed the subject; characterised in that it further includes means (44) for assembling radiation detected by the radiation detectors (24) into a plurality of views, each view being identifiable by an angular position (φ, ϑ) around the subject and an axial position R along a spiral path; interpolating means (46) for interpolating angularly corresponding views collected over more than two revolutions around the generally spiral paths; reconstructing means (54) for reconstructing the interpolated views into a plurality of image representations; and memory means (56) for storing the plurality of image representations.

Claim 37

An imaging apparatus including: means (20, 32) for moving a subject and a radiation source (12) such that the subject is irradiated along a generally spiral path; and at least one arc of radiation detectors (24) for detecting radiation from the source (12) which has traversed the subject; characterised in that it further includes means (44) for assembling detected radiation into a plurality of views, each view having data generated from radiation that traversed the subject along a plurality of rays, each ray having an identifiable angular position (β,α) within a view and each view being identifiable by an angular position (φ, ϑ) around a spiral path and a longitudinal position R along the spiral path; filtering means (46) for filtering views identified by the same angular position (β,α) with a filter function (82, 84, 86, 88, 116, 118); reconstrucing means (54) for reconstructing groups of views, which nominally span 180°, into a plurality of image representations; and memory means (56) for storing the plurality of image representations.

Claim 38

An imaging apparatus including: a source of radiation (12); means (20) for rotating the source of radiation (12) around a subject; and at least one arc of radiation detectors (24) for converting radiation from the source (12) which has traversed the subject into a plurality of views, each view including data converted from a fan shaped array of radiation rays with an apex (28) of each fan shaped array disposed at an identifiable angular position (φ, ϑ) around the subject; characterised in that it further includes subject monitoring means (90) for monitoring a preselected cyclic movement of said subject; controlling means (92) operatively connected to the radiation source rotating means (20) and the monitoring means (90) for controlling relative rotation of the source (12) in accordance with the monitored cyclic movement; reconstructing means (54) for reconstructing the views into at least one image representation; and memory means (56) for storing the at least one image representation.

Claim 39

An imaging apparatus including: subject supporting means (30) for supporting a subject in an examination region (14); a radiation source (12) for irradiating a portion of the subject in the examination region (14) with penetrating radiation; means (20) for rotating the radiation source (12) around the examination region (14); means (32) for longitudinally advancing the patient supporting means (30) through the examination region (14) at a generally constant velocity; means (24) for detecting said radiation; means (44) for assembling the detected radiation into a plurality of views; filtering means (46) for filtering the views; reconstructing means (54) for reconstructing the filtered views into a plurality of image representations; and memory means (56) for storing the image representations; characterised in that said means (24) for detecting said radiation comprises at least two parallel arcs of radiation detectors (24) disposed generally parallel to a path of radiation from said source (12) for concurrently detecting radiation which has traversed the subject along at least two longitudinally spaced arcs; and each view is identifiable by an angular position (φ, ϑ) relative to the subject and a longitudinal position R along at least two interleaved spiral paths around the subject.

Claim 40

An imaging appaaratus including: a source of radiation (12); means (20) for rotating the source of radiation (12) around an examination region (14); radiation source energy control means (104) for controlling an energy output of the radiation source (12); at least one arc of radiation detectors (24) for detecting rays of radiation which have traversed the subject; means (44) for assembling detected radiation into a plurality of views, each view representing rays meeting at an apex (28) at an identifiable angle (φ, ϑ) within the examination region (14, 214); reconstruction means (54) for reconstructing the views into an image representation; characterised in that the radiation source energy controlling means (104) causes the radiation source energy to vary between at least two energy levels.

Claim 41

An imaging apparatus including: a source of radiation (12); radiation source energy control means (104) for controlling an energy of radiation generated by the radiation source (12); means (16, 20) for rotating the radiation source (12) around an examination region (14); means (32) for advancing a patient supporting means (30) longitudinally through the examination region; at least one arc of radiation detectors (24) for detecting rays of radiation from the source (12) which has traversed the examination region (14); characterised in that it further includes means for organizing radiation (44) detected by the radiation detectors (24) into a plurality of views, each view representing a fan shaped array of radiation rays with an apex (28) of the array disposed at an identifiable angular position (φ, ϑ) within the examination region (14); filtering means (46) for filtering the views with a filter function (66, 68, 70, 82, 84, 86, 88, 94, 98, 116, 118); monitoring means (22, 34, 104) for monitoring at least one of a speed of radiation source rotation, a speed of patient supporting means (30) longitudinal advancement, and an energy of the radiation source; means (50, 92) operatively connected with the monitoring means (22, 34, 104) for controlling at least one of the speed of rotation of the radiation source (12), the speed of longitudinal advancement of the patient supporting means (30), the energy of the radiation source (12), and/or selecting the filter function (66, 68, 70, 82, 84, 86, 88, 94, 98, 116, 118); reconstructing means (54) for reconstructing the views into image representations; and memory means (56) for storing the image representations.

Claim 42

An imaging apparatus including: a source of radiation (12); means (16, 20) for rotating the source of radiation (12) around an examination region (14); means for determining an angular position (φ, ϑ) of the source of radiation (12) around the examination region (14); at least one arc of radiation detectors (24) for detecting radiation from the radiation source (12) that has traversed the examination region (14); means (44) for assembling the detected radiation into a plurality of views; filtering means (52) for filtering each view with a filter function (62, 66, 68, 70, 82, 84, 86, 88, 94, 98, 116, 118); reconstructing means (54) for reconstructing the views into at least one image representation; memory means (56) for storing the at least one image representation; characterised in that each view is identifiable by an angular position (φ, ϑ) within the examination region (14) and in that said apparatus comprises filter function selecting means (48) for selecting a filter function corresponding to the angular position (φ, ϑ) of each view.

Claim 43

An imaging apparatus including: a source of penetrating radiation (12); means (16, 20) for rotating a source of radiation (12) around an examination region (14); means (32) for advancing a subject through the examination region (14); means (32) for advancing a subject through the examination region; at least one arc of radiation detectors (24) for detecting radiation from the radiation source (12) that has traversed the examination region (14); means (44) for organizing the collected radiation into a plurality of views of data; filtering means (46) for filtering data representing each ray of each view with a filter function; reconstructing means (54) for reconstructing the image representations from the views; and memory means (56) for storing the image representations, characterised in that each view represents a plurality of rays of radiation extending in a fan shaped array from an apex at an identifiable angle (φ, ϑ) around the examination region (14); and in that said filter function is selected in accordance with the identifiable angle (φ, ϑ) of the view within the examination region and an angle (β,α) of each ray within the corresponding view.