Okay, concerning carbon 14, I think that's what you're refering to - it only works with dead material. The theory is, that a living being ingests carbon as long as it is alive. The amount of carbon 14 (carbon with 14 neutrons) doesn't change as long as you eat and drink. When a living being dies, the amount of carbon 14 reduces according to its half-life . It's great to find out the age of something actually old, but it doesn't help much when you want to now if something's been dead for 100 or 50 years.
Other procedures...
Well there's PET (Positron Emission Tomography) used as an imaging procedure. You get FDG, which is Glucose ( a special type of sugar) with a F-atom (Fluor (?))instead of an Oxygen-atom. I'm not sure how long it's half-life is. Long enough for the imaging procedure, but it will wear off pretty quickly.
Another imaging procedure is bone- szinthigraphy, usually done with Technetium. It's used to find places of high metabolism (such as inflammation or tumor). The half-life of Technetium is about 8 hours, I believe.
An imaging procedure using radioactivity deals with substances that have a rather short half-time. Substances with long half time are used to cure people with tumors.
Dating a fracture will be difficult when it's healed. As long as the fracture is still relatively fresh that could be done rather accurately, I think.
Dating a bug bite - huh, I guess that depends on the grade of healing the wound shows. It would be difficult.
