Each tracer has its own affinity for tissues. For example some are more likely to attach to areas of bone and can be used to look at the spine. Any increased area of cell growth or tissue repair will usually mean increased concentration of the tracer.

Fractures or other injuries to the bone show up as a hot-spot seen easily on the image. This represents a place where there is an increase or build-up of the dye.

Nuclear scanning is non-invasive, but it does involve exposure to ionizing radiation. And exposure to radiation does have the potential to cause problems. Damage to the DNA and the possibility of cancer are the major concerns.

However, based on studies to date, the radiation doses delivered to a patient in this type of imaging have a very small chance of causing cancer. The total dose of radiation is small -- more than a chest x-ray but less than a CT scan of the chest. The difference is that the dose using nuclear imaging with a PET scan is delivered internally rather than externally from the X-ray.