A surgical apparatus, the apparatus comprising: (a) a cutting tool comprising an axial member with a proximal end and a distal end, the axial member characterized by at least two adjacent axial sections, wherein differences between each of the sections are visually discernible when viewed in a projection x-ray image; and (b) a hollow tube adapted for parallel alignment with the cutting tool and selectively axially positionable to be adjacent at least a selective one of said axial sections and block x-ray radiation from at least one of passing through or passing adjacent said selected section so that said projection indicates a relative axial position of said hollow tube and said cutting tool.
1. A surgical apparatus, the apparatus comprising:
(a) a cutting tool comprising an axial member with a proximal end and a distal end, the axial member characterized by at least two adjacent axial sections which do not form a part of a cutting tip of said tool, wherein differences between each of the sections are visually discernible when viewed in a projection x-ray image, wherein said visually discernible difference results from an outer radial section of reduced radio-opacity; and
(b) a hollow tube adapted for parallel alignment with the cutting tool and selectively axially positionable to be adjacent at least a selective one of said axial sections and block x-ray radiation from at least one of passing through or passing adjacent said selected section so that said projection image indicates a relative axial position of said hollow tube and said cutting tool.
2. Apparatus according to claim 1 , wherein the cutting tool is adapted for bone access.
3. Apparatus according to claim 2 , wherein the cutting tool is adapted for vertebral access.
4. Apparatus according to claim 1 , wherein said hollow tube comprises a sleeve adapted to contain at least an axial portion of the cutting tool.
5. Apparatus according to claim 4 , wherein said sleeve has an inner diameter which is adapted to ensure substantial contact with said cutting tool.
6. Apparatus according to claim 1 , wherein said hollow tube comprises a partial sleeve which does not circumferentially surround the cutting tool adjacent said sections.
7. Apparatus according to claim 1 , wherein said hollow tube blocks said radiation from at least part of said selected section.
8. Apparatus according to claim 1 , wherein said hollow tube blocks said radiation from an area adjacent said selective section.
9. Apparatus according to claim 1 , wherein said outer radial section comprises a filled-in groove.
10. Apparatus according to claim 1 , wherein said cutting tool comprises at least one radially distal hollow.
11. Apparatus according to claim 10 , wherein said radially distal hollow does not reach a distal end of said cutting tool.
12. Apparatus according to claim 1 , wherein said visually discernible differences are rotationally symmetric, with respect to rotation of said cutting tool and said hollow tube with respect to said x-ray radiation.
13. Apparatus according to claim 1 , wherein said visually discernible differences are each axially uniform.
14. Apparatus according to claim 1 , wherein at least one of the axial sections comprises an axially varying profile.
15. Apparatus according to claim 14 , wherein the axially varying profile comprises a series of axially separated decreased radio-opaque diameter portions.
16. Apparatus according to claim 1 , wherein at least one of said axial sections comprises an axially extending spiral of at least partly radio-opaque material.
17. Apparatus according to claim 1 , wherein the cutting tool comprises an inner lumen.
18. Apparatus according to claim 17 , comprising a guide element adapted for insertion through the inner lumen.
19. Apparatus according to claim 1 , wherein said cutting tool comprises a bone penetrating element and said hollow tube comprises a bone cannula.
20. Apparatus according to claim 19 , wherein said bone cannula has a wall thickness of 0.4 mm or less.
21. Apparatus according to claim 20 , wherein said bone cannula has a wall thickness of 0.3 mm or less.