Tracers – Nuclear Medicine?
October 11, 2009 by
Filed under nuclear medicine camera
is this information correct (concerning tracers in nuclear medicine)
- a radioactive substance is inject into shoulder [or body], or swallowed through mouth
- radioactive substances are generally gamma emitters
- We use a gamma camera to detect the tracer
- We use gamma rays for tracing as they can easily pass through the body without damaging it. Secondly we use a substance with a relativity short half-life (a few hours), long enough to take measurements but short enough not to cause damage.
- Tracers are used to create a picture of an organ or an organ system by detecting where the strongest readings are coming from
- Along with the tracer, a radionuclide is injected, to guide the tracer to a certain part of the body
The most important part of this thing is the last bullet point (Is that correct?)
I don’t think so, John. The tracer is the radionuclide. What you would tend to do is use a radionuclide of a chemical which is either taken up or processed by the organ you’re looking for – e.g. Iodine in the thyroid. I think.
The majority of radiopharmaceuticals are injected intravenously (IV), and not just into the tissue.
These are some, but not all, that are injected IV: Cardiolite (sestamibi), Myoview (tetrofosmin), Choletec (mebrofenin), MDP, HDP, MAA, MAG-3.
These (some not all) are usually given orally: I-123 capsule, I-131 capsule (for therapy), and sulfur colloid (for gastric emptying, etc.) Xe-133 gas (lung ventilation).
The majority of the radiopharmaceuticals used are tagged with Technetium-99m and are gamma emitters.
Gamma cameras are used to detect the tracers.
“We use gamma rays for tracing as they can easily pass through the body without damaging it. Secondly we use a substance with a relativity short half-life (a few hours), long enough to take measurements but short enough not to cause damage.”- I agree with that, however some of the tracers used will have a longer half life.
The radionuclide is the radioactive part which is tagged with the specific compound for that specific drug. Together they form the radiotracer or radiopharmaceutical.
After we inject (times vary depending on scan) we wait and then image. We are usually taking pictures of how well an organ or an organ system is functioning. The keyword is functioning.
You give the appropriate drug for the appropriate organ system and then you position the patient’s body accordingly. The drugs won’t go to one place only… sometimes they will highlight several organs and not just the intended one.