Radiation is used in nuclear medicine and radiology. In nuclear medicine, radioactive materials known as radioisotopes, or radiopharmaceuticals, are introduced into the body. In radiology, X-rays enter the body from outside.
According to the Center for Nuclear Science and Technology Information, about one-third of all procedures used in modern hospitals involve radiation or radioactivity. The procedures offered are effective, safe, and painless and they do not need anesthesia.
Nuclear medicine is used to diagnose a wide range of conditions.
The patient will inhale, swallow, or be injected with a radiopharmaceutical. This is a radioactive material. After taking the substance, the patient will normally lie down on a table, while a camera takes pictures.
The camera will focus on the area where the radioactive material is concentrated, and this will show the doctor what kind of a problem there is, and where it is.
Types of imaging techniques include positon emission tomography (PET) and single-photon emission computed tomography (SPECT).
PET and SPECT scans can provide detailed information about how a body organ is functioning.
This type of imaging is particularly helpful for diagnosing thyroid disease, gall bladder disease, heart conditions, and cancer. It can also help diagnose Alzheimer's disease and other types of dementia and brain conditions.
In the past, diagnosing internal problems often needed surgery, but nuclear medicine makes this unnecessary.
After diagnosis, and when treatment starts, PET and SPECT can show how well the treatment is working.
Other types of imaging involved in nuclear medicine include targeted molecular ultrasound, which is useful in detecting different kinds of cancer and highlighting blood flow; and magnetic resonance sonography, which has a role in diagnosing cancer and metabolic disorders.
Radioactive techniques are also used in treatment. The same agents that are used in nuclear imaging can be used to deliver treatment. The radiopharmaceutical can be swallowed, injected, or inhaled.
One example is radioactive iodine (I-131). It has been used for over 50 years to treat thyroid cancer and hyperthyroidism, or an overactive thyroid. Now, it is also used to treat non-Hodgkin lymphoma and bone pain from some kinds of cancer.
Iodine-131 (I-131) targeted radionuclide therapy (TRT) introduces radioactive iodine into the body. As the thyroid cells or cancer cells absorb this substance, it kills them. I-131 can be given as capsules or in liquid form.
In the future, it may be possible to embed chemotherapy into medication imaging agents that will attach only to cancer cells. In this way, the chemotherapy would kill only the target cells and not the nearby healthy tissue. This would reduce some of the adverse effects of chemotherapy.
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-131, or radioactive iodine therapy (RAI). Other options include 90Y-ibritumomab tiuxetan, or Zevalin, which is used to treat different types of lymphoma. 131-I-tositumomab, or Bexxar, is used to treat lymphoma and multiple myeloma.
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.
When a patient has treatment for the thyroid with I-131, no special equipment is used.
A single, prepared dose will be taken by mouth. This is a one-time treatment.
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.
Women are advised to avoid becoming pregnant for 6 to 12 months following treatment.
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.
Too much radiation can potentially damage organs or tissues or increase the risk of cancer.
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.
Treatment with nuclear medicine involves larger doses of radioactive material.
This additional dose may affect the patient, and side effects are possible.
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 Nuclear Regulatory Commission (NRC) and the U.S. Food and Drug Administration (FDA) closely regulate the use of radioactive materials for nuclear medicine to ensure the safety of patients.