The nuclear medicine speciality may be a non-invasive technique for learning interrupted by the use of nuclear imaging techniques. Departments typically performed these tests while the person was undergoing training. Nuclear medicine is a technique that uses small amounts of radioactive substances called radiotracers, which are usually injected, aspirated, or embedded in the blood. Angiography can even be a medical imaging technique for determining the lumen of blood vessels and organs of the body, paying close attention to arteries, veins and thus the intestine. This can be done by inoculating the blood vessel with a radiopaque contrast agent and imaging it with an X-ray-based technique such as radiography.