Image acquisition devices with contrast and spatial resolution enhanced back-scatter shielding

1. An image acquisition device, comprising:

a conversion layer adapted to produce visible light photons or electrical charges in response to radiation at Megavolt energy levels;

a detector array adapted to detect the produced visible light photons or electrical charges, said detector array comprising a substrate and a plurality of detector elements over the substrate; and

a layer of a low-Z material behind the substrate to scatter back radiation that passes through the detector array.

2. The image acquisition device of claim 1 wherein the low-Z material comprises an element that has an atomic number equal to or smaller than 30.

3. The image acquisition device of claim 1 wherein the low Z-material is selected from the group consisting of silicon, carbon, beryllium, and titanium.

4. The image acquisition device of claim 1 wherein the detector array comprises a plurality of detector elements defining an active detection area, and the layer of the low-Z material extends an area that is at least equal to or greater than the active detection area.

5. The image acquisition device of claim 1 further comprising a layer of a high-Z material behind the layer of the low-Z material.

6. The image acquisition device of claim 5 wherein the detector array comprises a plurality of detector elements defining an active detection area, and the layer of the high-Z material extends an area that is at least equal to or greater than the active detection area.

7. The image acquisition device of claim 5 wherein the detector array comprises a plurality of detector elements defining an active detection area, and the layer of the high-Z material extends an area that is smaller than the active detection area.

8. The image acquisition device of claim 5 wherein the detector array comprises a plurality of detector elements defining an active detection area, and at least the layer of the low-Z material extends an area that is at least equal to or greater than the active detection area respectively.

9. The image acquisition device of claim 5 wherein the high-Z material comprises an element that has an atomic number equal to or greater than 50.

10. The image acquisition device of claim 1 wherein the conversion layer comprises scintillators adapted to produce visible light photons in response to X-ray radiation.

11. The image acquisition device of claim 1 wherein the low-Z material comprises aluminum.

12. The image acquisition device of claim 1 wherein the low Z-material has a thickness ranging from about 0.5 mm to about 3 mm.

13. An image acquisition device comprising:

a conversion layer comprising photoconductors configured to produce electron-hole charges in response to X-ray radiation;

a detector array configured to detect the produced electron-hole charges; and

a layer of a low-Z material configured to scatter back radiation that passes through the detector array.

14. The image acquisition device of claim 13 wherein the low Z-material is selected from the group consisting of aluminum, silicon, carbon, beryllium, and titanium.

15. A radiation apparatus, comprising:

a radiation source operable to produce radiation at Megavolt energy levels;

an image acquisition device; and

a support structure adapted to position the image acquisition device relative to the radiation source;

wherein the image acquisition device comprises a radiation conversion layer to produce visible light photons or electrical charges in response to radiation at Megavolt energy levels, a detector array to detect the produced visible light photons or electrical charges, and a layer of a low-Z material behind the detector array to scatter back radiation that passes through the detector array.

16. The radiation apparatus of claim 15 wherein the low-Z material comprises an element that has an atomic number equal to or smaller than 30.

17. The radiation apparatus of claim 15 wherein the low Z-material is selected from the group consisting of aluminum, silicon, carbon, beryllium, and titanium.

18. The radiation apparatus of claim 15 wherein the detector array comprises a plurality of detector elements defining an active detection area, and the layer of the low-Z material extends an area that is at least equal to or greater than the active detection area.

19. The radiation apparatus of claim 18 wherein the high-Z material comprises an element that has an atomic number equal to or greater than 50.

20. The radiation apparatus of claim 15 further comprising a layer of a high-Z material between the layer of the low-Z material and the support structure.

21. The image acquisition device of claim 20 wherein the detector array comprises a plurality of detector elements defining an active detection area, and at least the layer of the low-Z material extends an area that is at least equal to or greater than the active detection area respectively.

22. The radiation apparatus of claim 15 , wherein the detector array comprises a substrate and a plurality of detector elements over the substrate, and the layer of the low-Z material is disposed behind the substrate.

23. An imaging method, comprising the steps of:

passing x-ray radiation at Megavolt energy levels through a conversion layer comprising a scintillator, thereby a minor portion of the x-ray radiation is converted into visible light and a major portion of the x-ray radiation passes through the conversion layer;

scattering the major portion of the x-ray radiation that passes through the conversion layer using a layer of a low Z-material, thereby additional visible light is generated by x-ray radiation scattered back into the conversion layer;

detecting the visible light and the additional visible light using a detector array.

24. The imaging method of claim 23 wherein the low-Z material is selected from the group consisting of aluminum, silicon, carbon, beryllium, and titanium.