Many of you will know that I mostly write about physics. My knowledge of human biology is limited to being reasonably certain that I have a body. At one point, some of my research could have had a medical application, but it involved diseases, which was knowledge I didn’t have. A recent paper on using quantum effects to improve medical diagnosis has given me flashbacks to those halcyon days, even though I still don't understand diseases.
One thing I am aware of is that it is usually preferable to be diagnosed for a disease early. It might be the difference between taking a pill and having your liver decorate a surgeon’s instruments. That means your doctor needs a cheap and effective way to see whether you have the disease. This is where, hopefully, physicists—and maybe even some physics—can come into play.
Most diseases release proteins or other molecules that signal the problem. If you have sensitive enough detectors, then you can pick up these signals and identify potential problems early. The challenge is that almost all tests of this sort are concentration sensitive: that is, if there aren’t many molecules, the signal will be weak and the test will return a false negative.