Reconstruction stabilizer and active vision
A method for stabilizing the reconstruction of an imaged volume is presented. The method includes the steps of performing an analysis of the reliability of reconstruction of a radioactive-emission density distribution of the volume from radiation detected over a specified set of views, and defining modifications to the reconstruction process and/or data collection process to improve the reliability of reconstruction, in accordance with the analysis.
1. A method of radioactive-emission measurements of a body structure, comprising:
performing radioactive-emission measurements of the body structure, at a predetermined set of views taken from different directions;
analyzing the radioactive-emission measurements from the different view directions including extracting a detected photon count; and
dynamically defining at least one view parameter for further radioactive measurements based on said photon count detected from the different view directions from at least a target region, and
matching said dynamically defined at least one view parameter to one or more particular views and view directions.
2. The method of claim 1 , wherein said performing is in vivo.
3. The method of claim 1 , comprising reconstructing a 3D non-coincidence image from said measurements.
4. The method of claim 1 , wherein said performing is for diagnostic purposes.
5. The method of claim 1 , wherein said performing is as part of a pre-scan.
6. The method of claim 1 , wherein said at least one acquisition parameters comprises a view selection of a plurality of views.
7. The method of claim 6 , further comprising performing radioactive-emission measurements of the body structure, at said plurality of views.
8. The method of claim 6 , wherein each of said views is associated with viewing parameters selected from the group consisting of: detector unit location, detector unit orientation and collection angle.
9. The method of claim 6 , wherein each of said views is associated with a measurement duration.
10. The method of claim 1 , wherein dynamically defining comprises defining at least one view measurement duration to achieve a desired photon count.
11. The method of claim 1 , wherein dynamically defining comprises defining at least one view measurement duration to achieve a desired total photon count from at least a region of interest.
12. A method according to claim 1 , wherein said analyzing comprises estimating a measurement error provided by a photon count at a given view.
13. A method according to claim 12 , wherein said defining comprises extending a duration of a view to obtain a required error value or better.
14. A method according to claim 12 , wherein said defining comprises adding views to obtain a required error value or better.
15. A method according to claim 1 , wherein said analyzing comprises determining that a photon collection rate at a given view is within a specified range.
16. A method according to claim 1 , wherein said defining comprises selecting views to reduce acquisition time from regions of low interest.
17. A method according to claim 1 , wherein said defining comprises selecting views to increase acquisition time viewing regions of high interest.
18. A method according to claim 1 , wherein said analyzing comprises identifying detector saturation at a given view.
19. A method according to claim 18 , wherein said defining comprises selecting views to reinforce views that have saturated.
20. A method according to claim 1 , wherein said analyzing comprises forming a reconstruction of a radioactive-emission density distribution of said body structure.
21. A method according to claim 20 , wherein said analyzing comprises identifying edges within said a volume reconstructed by said reconstructing.
22. A method according to claim 21 , wherein said defining comprises selecting views at an angle to said edges.
23. A method according to claim 22 , wherein said angle is a substantially sharp angle.
24. A method according to claim 20 , wherein said analyzing comprises identifying volumetric boundaries within said reconstruction.
25. A method according to claim 24 , wherein said defining comprises selecting views at an angle to said volumetric boundaries.
26. A method according to claim 25 , wherein said angle is substantially sharp angle.
27. A method according to claim 20 , wherein said defining comprises selecting views covering regions in close proximity to a suspected target organ target.
28. The method of claim 1 , wherein said method is performed iteratively.
29. The method of claim 20 , wherein said method is performed iteratively.
30. A method according to claim 29 , wherein said analyzing comprises determining a variance of a plurality of reconstructions.
31. A method according to claim 30 , wherein said defining comprises selecting views to reduce the variance between iterations of reconstruction of a region of high interest to a required level.
32. A method according to claim 20 , wherein said analyzing comprises determining an accuracy of said reconstruction.
33. A method according to claim 20 , wherein said analyzing comprises determining a resolution of said reconstruction.
34. A method according to claim 1 , wherein said dynamically defining comprises:
providing a quality function for rating a quality of information obtainable from said measurements by said quality function; and
selecting a set of views to maximize said quality function.
35. A method according to claim 34 , wherein the quality function is based on an information theoretic measure of separability.
36. A method according to claim 34 , wherein the quality function is based on the reliability of reconstruction of a radioactive-emission density distribution.
37. A method according to claim 34 , wherein the quality function is based on an information-theoretic Fisher information measure.
38. A method according to claim 37 , wherein the Fisher information measure is a non-scalar measure.
39. A method according to claim 34 , further comprising increasing said selected set of views by at least one randomly selected view.
40. The method of claim 34 , wherein said dynamically defining comprises:
providing a collection of views of said body structure;
establishing said predetermined set of views as a current set of views; and
iteratively expanding said current set until a predefined number of further views are obtained, wherein a set expansion iteration comprises:
forming a respective expanded set for said collection of views and not in said current set, wherein an expanded set comprises said current set and a respective view;
calculating a respective score for each of said expanded sets using said quality function;
selecting said respective view of a highest-scoring expanded set as a further view; and
equating said current set to said highest-scoring expanded set.
41. The method of claim 1 , wherein dynamically defining comprises selecting a set of views, selected by a method of:
providing a model of a volume;
providing a collection of views of said volume;
providing a scoring function, by which any set of at least one view from said collection is scorable with a score that rates information obtained from said volume by said set;
forming sets of views and scoring them, by said scoring function; and
selecting a set of views from said sets, based on said scoring function.
42. The method of claim 41 , wherein each of said views is associated with viewing parameters comprising a detector location and orientation.
43. The method of claim 41 , wherein each of said views is associated with viewing parameters selected from the group consisting: of measurement duration, time elapsed from the administration of the pharmaceutical to the measurement, radiopharmaceutical half life, radioactive emission type, and radioactive emission energy.
44. The method of claim 41 , wherein said selecting is to obtain a minimal-size set which attains a predefined score.
45. The method of claim 41 , wherein providing a model comprises providing at least one emittance model, wherein an emittance model comprises a representation of a radioactive-emission density distribution of said volume.
46. The method of claim 45 , wherein said providing at least one emittance model includes modeling a radioactive-emission density distribution to form at least one modeled organ target.
47. The method of claim 45 , wherein:
said providing at least one emittance model comprises providing a plurality of emittance models of substantially identical volumes, but different modeled organ targets;
the forming sets of views from the collection of views and scoring them, comprises forming substantially identical sets of views for all the models and scoring the sets with respect to each model, based on the information theoretic measure of reliability; and
the selecting a sets of views, based on its score, comprises selecting based on the average score for the plurality of models.
48. The method of claim 45 , wherein:
said providing at least one emittance model comprises providing a pair of models of substantially identical volumes, but different modeled organ targets, wherein the difference between the modeled organ targets is defined by at least one delta;
the scoring function is based on an information theoretic measure of separability;
the forming the sets of views from the collection of views and scoring them, comprises forming substantially identical sets of views for the pair of models and scoring the sets with respect to the pair; and
the selecting a sets of views, based on its score, comprises selecting based on the score for the pair.
49. The method of claim 45 , wherein:
said providing at least one emittance model comprises providing a plurality of pairs of models of substantially identical volumes, but different modeled organ targets, wherein the difference between the modeled organ targets for each pair is defined by at least one delta;
the scoring function is based on an information theoretic measure of separability;
the forming the sets of views from the collection of views and scoring them, comprises forming substantially identical sets of views for the plurality of pairs of models and scoring the sets with respect to each of the pairs; and
the selecting a sets of views, based on its score, comprises selecting based on an average score for the plurality of pairs.
50. The method of claim 45 , wherein:
the modeling the body-structure comprises providing at least one model of no radiation emission density distribution and at least two models of different radiation emission density distributions, so as to form different modeled organ targets for those two models; and
the providing the scoring function comprises providing a scoring function as a combination of uniformity, separability and reliability.
51. The method of claim 45 , wherein said scoring function comprises a worst-case effectiveness for said given view over said set of emittance models.
52. The method of claim 45 , wherein said scoring function comprises an average effectiveness for said given view over said set of emittance models.
53. The method of claim 45 , wherein said set of emittance models comprises a single emittance model.
54. The method of claim 45 , wherein said at least one emittance model corresponds to said body structure.
55. The method of claim 54 , wherein said body structure comprises one of a group of body structures comprising: a prostate, a heart, a brain, a breast, a uterus, an ovary, a liver, a kidney, a stomach, a colon, a small intestine, an oral cavity, a throat, a gland, a lymph node, the skin, another body organ, a limb, a bone, another part of the body, and a whole body.
56. A method of radioactive-emission measurements of a body structure, comprising:
performing radioactive-emission measurements of the body structure, at a predetermined set of views;
analyzing the radioactive-emission measurements including extracting a detected photon count; and
dynamically defining at least one view parameter for further radioactive measurements based on said photon count detected from at least a target region,
wherein said at least one view parameter is one or more of a detector position, a detector angular orientation, and the duration of particular views.