Nuclear Medicine Therapy

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Nuclear Medicine Therapy

Definition

Nuclear medicine therapy involves the administration of a radioactive material to treat disease or other medical conditions.

Purpose

Nuclear medicine therapy may be used to treat the following diseases and conditions:

thyroid cancer
thyrotoxicosis
Grave's disease and hyperthyroidism
polycythemia vera
malignant peritoneal or pleural effusion
non-Hodgkin's lymphoma
rheumatoid arthritis
osteosarcoma
brain tumors
cancer-related bone pain

Radiopharmaceuticals are injected into or ingested by the patient to weaken or destroy malignant cells or tissue, thereby providing either a cure or palliative relief. Even though nuclear medicine therapy cannot cure certain conditions, it may relieve pain or other symptoms, and thereby improve the patient's quality of life.

Preparation

Because nuclear medicine therapy involves the use of radioactive substances, care must be taken to avoid radiation exposure that extends outside of the patient's room. Therapy should be performed in a properly shielded room and under supervision of a radiation or medical physicist. Some procedures may require that the patient be isolated from staff, other patients, and visitors for several hours or days. Many radiopharmaceuticals are excreted via the patient's urine, perspiration, and saliva. Therefore, private rooms and private restrooms are usually required. Patient linens, food, personal items, and waste must be disposed of properly because of potential radiation contamination. When therapy or isolation are in progress, nursing and housekeeping staff must be informed that no items may be removed from the patient's room without first being cleared by radiation safety staff. Radiation-contaminated items that must be reused are generally measured for radioactivity levels with a radiation survey meter. If these items prove to be contaminated above what is considered normal background radiation levels, the items must be isolated and allowed to "decay" to safe levels. For some items, this may take up to 90 days.

Surveys of the patient's room and surrounding areas must be conducted at regular intervals to determine whether any radioactivity is present. Staff members must also be monitored for radiation exposure. The U.S. Nuclear Regulatory Commission regulates safety protocols for handling patients treated with radioactive materials and all facilities should be familiar with these regulations.

For patients treated in an outpatient setting, they and their family members and caregivers should be educated regarding radiation contamination and exposure in the home environment following the therapeutic procedure.

Description

Nuclear medicine is a medical subspecialty that uses radioactive compounds called radionuclides or radiopharmaceuticals to diagnose or treat metabolic, physiologic, and pathologic conditions. In nuclear medicine therapy, a radiopharmaceutical is injected into or ingested by a patient to treat a specific medical condition. In contrast, diagnostic nuclear medicine uses radionuclides or radioisotopes combined with a medical imaging system to assist in diagnosing a particular medical condition.

Nuclear medicine produces radiation within the body. The radiation emitted by the administered radiopharmaceutical is toxic to cancer cells or tissue. The most commonly used radioactive element in nuclear medicine therapy is iodine-131, which is used to treat thyroid cancer and other thyroid conditions. Phosphorus-32 is used to treat polycythemia vera and malignant peritoneal/pleural effusion. For palliative treatment of cancer-related bone pain, rhenium-186, strontium-89, and samarium-153 are used. Samarium-153 is also being used to treat joint pain associated with rheumatoid arthritis. Yttrium-90 or iodine-131 may be used in combination with a monoclonal antibody to treat non-Hodgkin's lymphoma.

Each radioactive element used for therapy has a different half-life—the amount of time necessary for it to decay to half the initial radiation dose or for half the initial dose to be metabolized. Patient doses are based upon the half-life of the radiopharmaceutical used.

Preparation

All personnel who care for patients receiving nuclear medicine therapy must receive special training in the handling of radioactive materials. Patients themselves must also receive education regarding nuclear medicine therapy so they can minimize contamination of their surroundings or other individuals.

Depending on the type of procedure, form of the radiopharmaceutical (e.g., liquid, capsule, injection), and level of radiation dose, patient rooms may require special preparation, including laying of plastic mattress or absorbent floor coverings and posting of radioactive hazard signs. The health status of the patient should be assessed prior to administration of the radiopharmaceutical. Patients with coughing or sneezing may be more likely to contaminate their surroundings and other individuals. Incontinent patients must be catheterized to prevent radiation contamination through uncontrollable urination. Women of childbearing age should be tested for pregnancy.

Aftercare

Most aftercare involves monitoring the patient for side effects from the radiation dose and monitoring patient surroundings for potential radiation contamination so as to reduce the likelihood of staff and visitor exposure. For patients receiving therapy in the outpatient setting, family members and patients may receive wearable radiation monitoring devices to determine if they have been exposed to radiation following the procedure. Because some radiopharmaceuticals cause bone marrow or blood cell toxicity, patients may require regular blood tests for a specified time following the procedure.

Complications

Most nuclear medicine therapy procedures themselves are simple, involving an intravenous injection/ infusion or ingestion of a capsule. Complications related to the actual procedure are minimal. However, significant complications can result from improper dosing, radioactive spills, or other radioactive con-tamination from the radiopharmaceutical administration. Radioactivity may adversely affect healthy tissue in addition to tumors, and bone marrow toxicity, hair loss, gastrointestinal upset, dry mouth, and flu-like symptoms can result. However, side effects are generally not as severe as those associated with whole-body radiation therapy or chemotherapy.

Results

Successful nuclear medicine therapy can result in a permanent cure for the disease or condition. When used as palliative therapy, such as for cancer-related bone pain, nuclear medicine therapy will relieve pain and help improve the patient's quality of life.

Health care team roles

Nuclear medicine therapy involves many different health care team members, including the physician, nurse, nuclear medicine technologist, medical physicist, radiation safety personnel, and nuclear pharmacist. Depending on the condition being treated, endocrinologists, rheumatologists, and oncologists may all participate in the patient's care. Radiopharmaceuticals are prepared in the nuclear pharmacy by a pharmacist trained in handling of radioactive materials. A medical physicist and radiation safety personnel assist in establishing protocols for safe handling, administration, and clean-up of radioactive materials in accordance with federal guidelines. The medical physicist may also be present during the therapeutic procedure to ensure radiation safety. Nurses involved with patients receiving nuclear medicine therapy must be trained in radiation safety and how to minimize radiation contamination during patient care. While nuclear medicine technologists are primarily involved in diagnostic procedures, they may also be involved in patient care, quality control, and administration of therapeutic radiopharmaceuticals.

KEY TERMS

Monoclonal antibody— Laboratory-produced antibodies manufactured from a single clone of cells, which makes them pure and homogeneous. Used for targeted cancer therapy and other immunologic applications.

Palliative— Intended to control pain and make the patient more comfortable when a cure is not possible.

Polycythemia vera— A disease in which an excess of red blood cells is produced in the bone marrow

Radiopharmaceutical— A radioactive element, often combined with biologic components, that is used for a therapeutic application.

Resources

BOOKS

Kuni, Christopher C., and René P. duCret. Manual of Nuclear Medicine Imaging. New York: Thieme Medical Publishers, Inc., 1997.

PERIODICALS

Damerla, V., S. Packianathan, P. S. Boerner, et al. "Recent Developments in Nuclear Medicine in the Management of Bone Metastases: A Review and Perspective." American Journal of Clinical Oncology 28 (October 2005): 513-520.

Panzegrau, Beata, Leonie Gordon, and Glen H. Goudy, "Outpatient Therapeutic ¹³¹I for Thyroid Cancer." Journal of Nuclear Medicine Technology 33 (March 2005): 28-30.

Rutar, Frank J., Samuel C. Augustine, David Colcher, et al. "Outpatient Treatment with ¹³¹I-anti-B1 Antibody: Radiation Exposure to Family Members." Journal of Nuclear Medicine 42 (June 2001): 907-915.

Thompson, Michael A. "Radiation Safety Precautions in the Management of the Hospitalized ¹³¹I Therapy Patient." Journal of Nuclear Medicine Technology 29 (June 2001): 61-66.

Wahl, Richard L. "Tositumomab and ¹³¹I Therapy in Non-Hodkin's Lymphoma." Journal of Nuclear Medicine Technology 46 (January 2005 supplement): 128S-140S.