Briefly define nanotechnology and its use with imaging techniques

What will be an ideal response?

Nanotechnology works with matter on an almost molecular or cellular scale. Nanoparticles can be used as contrast agents. They can help detect cellular processes. As of 2011, nanoparticles called quantum dots or qdots were under development. They are nanocrystals of 1 to 10 nanometers. When light is focused on a qdot, it emits its own light; different size qdots emit different light. They are also brighter than other dyes.
The qdots can attach themselves to some cancer cells. "[I]njected into animal models, qdots produce high-resolution multicolored molecules" in the animals' cells. This makes it possible to track them over time. Eventually, they may be used to "generate a kind of optical barcode reflecting the levels of various tumor markers…indicat[ing] tumor type and stage."
Different kinds of nanoparticles are used with different imaging techniques. Suffice it to say that nanoparticles of different kinds can be used as contrast agents in MRIs, PET scans, and CT scans.