Procedures in which nuclear medicine is used

Radioimmunotherapy RIT combines nuclear medicine radiation therapy with immunotherapy. Immunotherapy is a treatment that mimics cellular activity in the body.

Combining the two types of treatment means the nuclear medicine can be targeted more directly to the cells that need it. Various radionuclides are used. The most common one is I, or radioactive iodine therapy RAI. Other options include 90Y-ibritumomab tiuxetan, or Zevalin, which is used to treat different types of lymphoma. Experts in nanotechnology, advanced polymer chemistry, molecular biology, and biomedical engineering are investigating ways to deliver the drugs to the correct site without affecting surrounding tissues.

Theranostics is an approach that integrates nuclear medicine techniques for diagnosis and imaging with those for treatment. By combining molecular targeting vectors, such as peptides, with radionuclides, it can direct the radioactive substance to the target area to diagnose and deliver treatment at the same time. A person who is going for diagnosis or treatment with nuclear medicine should be sure to inform the health professional if they are pregnant or breastfeeding, or if they may be pregnant.

The patient may have to wear a gown, or they may be able to wear their own clothes, but they will have to remove jewelry and other metal-base accessories.

The patient should not eat or drink after midnight on the day of the treatment. If the treatment is for a thyroid problem, the doctor will normally advise them to stop taking their regular thyroid medication between 3 and 7 days before the treatment. The patient may be able to return home after the dose, or they may have to stay overnight in the hospital. However, because the body will not absorb all the radioactive iodine, it will continue to leave the body over the next 2 to 5 days.

The individual should avoid contact with other people as far as possible, and especially with infants and pregnant women. This may mean taking time off work. They should also prepare their own food, avoid sleeping with another person, flush the lavatory twice after use, and wash their clothes and laundry separately. Most of the iodine will leave the body through the urine, but it is also excreted through tears, sweat, saliva, vaginal discharge, and feces.

Anyone who plans to travel immediately after treatment should get a letter from the doctor, as radioactivity may show up on scanning machines at airports. However, when used for diagnosis, the level of radiation exposure is around the same as a person receives during a routine chest x-ray or a CT scan. As a result, nuclear medicine and imaging procedures are considered non-invasive and relatively safe.

Their effectiveness in diagnosing disease means that the benefits normally outweigh the risks. For example, a nuclear medicine lung scan would expose a person to 2 millisieverts mSv of radioactivity, while cancer treatment would expose a tumor to 50, mSv.

However, since the treatment often targets potentially fatal diseases, the benefits tend to outweigh the risks. As technology advances, scientists hope that treatments will be more directed toward the tumor or disease, and less likely to affect the person as a whole. The cameras are mounted on a rotating gantry that allows the detectors to be moved in a tight circle around a patient who is lying motionless on a pallet.

PET scans also use radiopharmaceuticals to create three-dimensional images. A positron is a particle with roughly the same mass as an electron but oppositely charged. These react with electrons in the body and when these two particles combine they annihilate each other. This annihilation produces a small amount of energy in the form of two photons that shoot off in opposite directions. The detectors in the PET scanner measure these photons and use this information to create images of internal organs.

Click here to watch a short video about how PET scans work. SPECT scans are primarily used to diagnose and track the progression of heart disease, such as blocked coronary arteries. There are also radiotracers to detect disorders in bone, gall bladder disease and intestinal bleeding.

SPECT agents have recently become available for aiding in the diagnosis of Parkinson's disease in the brain, and distinguishing this malady from other anatomically-related movement disorders and dementias. The major purpose of PET scans is to detect cancer and monitor its progression, response to treatment, and to detect metastases. Glucose utilization depends on the intensity of cellular and tissue activity so it is greatly increased in rapidly dividing cancer cells. In fact, the degree of aggressiveness for most cancers is roughly paralleled by their rate of glucose utilization.

In the last 15 years, slightly modified radiolabeled glucose molecules F labeled deoxyglucose or FDG have been shown to be the best available tracer for detecting cancer and its metastatic spread in the body. Recently, a PET probe was approved by the FDA to aid in the accurate diagnosis of Alzheimer's disease, which previously could be diagnosed with accuracy only after a patient's death.

In the absence of this PET imaging test, Alzheimer's disease can be difficult to distinguish from vascular dementia or other forms of dementia that affect older people. Doctors use nuclear medicine to diagnose, evaluate, and treat various diseases.

These include cancer, heart disease, gastrointestinal, endocrine, or neurological disorders, and other conditions. Nuclear medicine exams pinpoint molecular activity. This gives them the potential to find disease in its earliest stages.

They can also show whether you are responding to treatment. Nuclear medicine is noninvasive. Except for intravenous injections, it is usually painless. These tests use radioactive materials called radiopharmaceuticals or radiotracers to help diagnose and assess medical conditions. Radiotracers are molecules linked to, or "labeled" with, a small amount of radioactive material.

They accumulate in tumors or regions of inflammation. They can also bind to specific proteins in the body. The most common radiotracer is F fluorodeoxyglucose FDG , a molecule similar to glucose.

Cancer cells are more metabolically active and may absorb glucose at a higher rate. This higher rate can be seen on PET scans. This allows your doctor to detect disease before it may be seen on other imaging tests.

FDG is just one of many radiotracers in use or in development. You will usually receive the radiotracer in an injection. Or you may swallow it or inhale it as a gas, depending on the exam. It accumulates in the area under examination. A special camera detects gamma ray emissions from the radiotracer. The camera and a computer produce pictures and supply molecular information.

Many imaging centers combine nuclear medicine images with computed tomography CT or magnetic resonance imaging MRI to produce special views. Doctors call this image fusion or co-registration. Image fusion allows the doctor to connect and interpret information from two different exams on one image.

This leads to more precise information and a more exact diagnosis. It is not currently available everywhere. Therapy Nuclear medicine also offers therapeutic procedures, such as radioactive iodine I therapy that use small amounts of radioactive material to treat cancer and other medical conditions affecting the thyroid gland, as well as treatments for other cancers and medical conditions.

Non-Hodgkin's lymphoma patients who do not respond to chemotherapy may undergo radioimmunotherapy RIT. Radioimmunotherapy RIT is a personalized cancer treatment that combines radiation therapy with the targeting ability of immunotherapy , a treatment that mimics cellular activity in the body's immune system.

See the Radioimmunotherapy RIT page for more information. Physicians use nuclear medicine imaging procedures to visualize the structure and function of an organ, tissue, bone or system within the body. Women should always tell their doctor and technologist if they are pregnant or breastfeeding. See the Safety in X-ray, Interventional Radiology and Nuclear Medicine Procedures page for more information about pregnancy and breastfeeding related to nuclear medicine imaging.

Tell the doctor and your exam technologist about any medications you are taking, including vitamins and herbal supplements. List any allergies, recent illnesses, and other medical conditions. Leave jewelry and accessories at home or remove them prior to the exam.

These objects may interfere with the procedure. In some instances, certain medications or procedures may interfere with the examination ordered. See the Radioactive Iodine I Therapy page for instructions on how to prepare for the procedure.

Nuclear medicine uses a special gamma camera and single-photon emission-computed tomography SPECT imaging techniques. The gamma camera records the energy emissions from the radiotracer in your body and converts it into an image. The gamma camera itself does not emit any radiation. It has radiation detectors called gamma camera heads. These are encased in metal and plastic, often shaped like a box, and attached to a round, donut-shaped gantry.

The patient lies on an exam table that slides in between two parallel gamma camera heads, above and beneath the patient. Sometimes, the doctor will orient the gamma camera heads at a degree angle over the patient's body.

In SPECT, the gamma camera heads rotate around the patient's body to produce detailed, three-dimensional images.

A PET scanner is a large machine with a round, donut-shaped hole in the middle. Multiple rings of detectors inside the machine record the energy emissions from the radiotracer in your body. A probe is a small hand-held device resembling a microphone. It measures the amount of radiotracer in an area of your body. There is no specialized equipment used during radioactive iodine therapy, but the technologist or other personnel administering the treatment may cover your clothing and use lead containers to shield the radioactive material you will be receiving.

Ordinary x-ray exams pass x-rays through the body to create an image. Nuclear medicine uses radioactive materials called radiopharmaceuticals or radiotracers. Your doctor typically injects this material into your bloodstream. Or you may swallow it or inhale it as a gas.

The material accumulates in the area under examination, where it gives off gamma rays. Special cameras detect this energy and, with the help of a computer, create pictures that detail how your organs and tissues look and function.

Unlike other imaging techniques, nuclear medicine focuses on processes within the body. These include rates of metabolism or levels of various other chemical activities. In radioactive iodine I therapy for thyroid disease, radioactive iodine I is swallowed, absorbed into the bloodstream in the gastrointestinal GI tract and absorbed from the blood by the thyroid gland where it destroys cells within that organ. Radioimmunotherapy RIT is a combination of radiation therapy and immunotherapy.

In immunotherapy, a laboratory-produced molecule called a monoclonal antibody is engineered to recognize and bind to the surface of cancer cells. Monoclonal antibodies mimic the antibodies naturally produced by the body's immune system that attack invading foreign substances, such as bacteria and viruses.