Imaging target for testing quality of multiple-magnification focus and image co-registration

1. An imaging target for use in a multimodal imaging system, the target comprising:

an optically clear, X-ray transparent substrate; and

at least one pattern formed on the substrate for testing at least one of:

the quality of image focus of one or more modalities of operation of the imaging system for a range of magnifications and illumination wavelengths, and

the quality of image co-registration of one or more modalities of operation of the imaging system for a range of magnifications and illumination wavelengths,

wherein the at least one pattern is formed from material which is:

X-ray opaque, and

optically reflective or optically absorptive, or both.

2. The imaging target according to claim 1 , wherein the at least one pattern comprises:

at least one layer of the material, the material forming a pattern which provides imaging contrast for one or more of the modalities of operation of an imaging system, with respect to the areas where the patterned material is absent; the pattern comprising features used for testing at least one of the quality of image focus or the quality of image co-registration.

3. The imaging target according to claim 2 , further comprising:

at least one alignment feature positioned corresponding to the at least one pattern for registering the imaging target to a feature of the imaging system to locate the at least one pattern in a field of view of the imaging system; and

at least one identification mark corresponding to the at least one pattern for providing information regarding the identity of the pattern.

4. The imaging target according to claim 3 wherein the at least one pattern includes:

a pattern of a recursively nested geometric shapes, the center of the pattern being suited to be aligned to a center of the field of view of the imaging system by the registration of the at least one alignment feature to a feature of the imaging system, and

the pattern of geometric shapes having a nesting pitch graded to lower pitch toward the center of the pattern to provide sufficient pattern content to test quality of focus for multiple magnifications of the imaging system.

5. The imaging target according to claim 4 , wherein the geometric shape is rectangular.

6. The imaging target according to claim 3 wherein the at least one pattern includes:

a pattern of an array of a geometric shape, the center of the pattern of an array being suited to be aligned to a center of the field of view of the imaging system by the registration of at least one alignment feature to a feature of the imaging system, and

the array pitch of the geometric shape being graded to lower pitch toward the center of the pattern to provide sufficient pattern content to test imaging system co-registration quality for multiple magnifications of the imaging system.

7. The imaging target according to claim 6 , wherein the geometric shape is circular.

8. The imaging target according to claim 1 wherein the modalities of operation of the imaging system include bright-field optical imaging at various wavelengths, fluorescence optical imaging at various wavelengths, and radiographic imaging at various energies.

9. The imaging target according to claim 1 wherein the at least one pattern is formed from a copper film.

10. The imaging target according to claim 1 wherein the at least one pattern is formed from silver ink.

11. The imaging target according to claim 1 wherein the substrate is optically clear polyester.

12. The imaging target according to claim 1 , wherein the at least one pattern is formed on a first side of the substrate, further comprising an optically white, X-ray transparent coating formed on a second side of the substrate opposite to the at least one pattern.

13. A method for testing the quality of image focus of an imaging system, the method comprising:

positioning an imaging target in the multimodal imaging system, the target comprising:

an optically clear, X-ray transparent substrate; and

at least one pattern formed on the substrate for testing the quality of image focus of one or more modalities of operation of the imaging system for a range of magnifications,

wherein the at least one pattern is formed from material which is: (a) X-ray opaque, and (b) optically reflective or optically absorptive, or both;

selecting a magnification of interest of the multimodal imaging system;

selecting a modality from the group comprising: optical modality and x-ray modality;

acquiring one or more images of the target at the selected magnification and selected modality;

evaluating the acquired images for a focus quality; and

adjusting the imaging system in response to the focus quality.

14. The method of claim 13 wherein the imaging target comprises two patterns.

15. A method for testing the quality of image focus of an imaging system, the method comprising:

positioning an imaging target in the multimodal imaging system, the target comprising:

an optically clear, X-ray transparent substrate; and

at least one pattern formed on the substrate for testing the quality of image co-registration of two modalities of operation of the imaging system for a range of magnifications,

wherein the at least one pattern is formed from material which is: (a) X-ray opaque, and (b) optically reflective or optically absorptive, or both;

selecting a field of view of the multimodal imaging system;

selecting a first modality from the group comprising: optical modality and x-ray modality;

acquiring one or more images of the target at the selected magnification and first modality;

selecting a second modality different from the first modality;

acquiring one or more images of the target at the selected magnification and second modality;

evaluating the acquired images for a focus quality; and

adjusting the imaging system in response to the focus quality.

16. The method of claim 15 wherein the imaging target comprises two patterns.

17. A method for testing the quality of image co-registration of an imaging system, the method comprising:

placing an imaging target in the multimodal imaging system, the target comprising:

an optically clear, X-ray transparent substrate; and

at least one pattern formed on the substrate for testing the quality of image co-registration of one or more modalities of operation of the imaging system for a range of magnifications and illumination wavelengths,

wherein the at least one pattern is formed from material which is: (a) X-ray opaque, and (b) optically reflective or optically absorptive, or both;

selecting a magnification of interest of the multimodal imaging system;

selecting the illumination wavelength or energy for the modality of interest;

acquiring two or more images of the target;

evaluating the co-registration quality of the acquired images; and

adjusting the imaging system in response to the co-registration quality.

18. The method of claim 17 wherein the imaging target comprises two patterns.