Radionuclide (Isotope) Scan

A radionuclide scan is a way of imaging bones, organs and other body parts of the body by using a small dose of a radioactive chemical. There are different types of radionuclide chemical. The one used depends on which organ or part of the body is to be scanned. The arrangements, and the way tests are performed, may vary between different hospitals.

A radionuclide is a chemical which emits a type of radioactivity called gamma rays. A tiny amount of radionuclide is put into the body, usually by an injection into a vein. 

There are different types of radionuclides. Different ones tend to collect or concentrate in organs or tissues.

Cells which are the most active in the target issue tissue or organ will take up more of the radionuclide. So, active parts of the tissue will emit more gamma rays than less active or inactive parts.

Gamma raysare similar to x-rays and are detected by a device called a gamma camera. The gamma rays which are emitted from inside the body are detected by the gamma camera, are converted into an electircal signal, and sent to a computer. The computer builds a picture by converting the differing intensities or radioactivity emitted into different shades of grey.

A bone scan: A radionuclide is used which collects in areas where there is alot of bone activity (cells are breaking down or making repairs to bone). So a bone scan is used to detect areas of bone where there is a cancer, infection, or damage.

Kidney scan: assess how well a kidney is working. So, scan can detect scars on the kidney, and how well uring drains from the kidney to the bladder. Lung perfusion scan can detect blood clots in the lungs.

Heart scan: can assess blood flow to the heart muscle. Areas of poor blood flow to the heart muscle do not take up the radionuclide very well and this will be shown in the picture.

Thyroid scan: assess cases of overactive thyroid.

Depending on the type of scan you have you can either swallow some radionuclide or it's injected into a vein in the arm. It takes some time (several hours) to travel to the target organ or tissue, and to be taken to the active cells. 

When you have the scan, you lie on a couch while the gamma camera detects the gamma rays coming from your body. The computer turns this information into an image.You need to lie as still as possible. Some pictures can take 20 minutes or more to expose.

The number of pictures being taken varies depending on what is being scanned. Some scans such as bone or heart scans may need two or more pictures. Each picture may be taken hours apart, so the process can take several hours.

They do not leave any after-effects. Though natural processes the radionuclide will decay, the radionuclide in your body will slowly lose it's radioactivity over time. It may also pass through your body quickly in the urine or stool. 

The radioactive chemicals used in radionuclide scans are considered to be safe, and they leave the body quickly in the urine. The dose you recieve is very small - in most cases its the same amount of radiation as you recieve in an x-ray.

Stay away from pregnant women.