Iridium seeds
Iridium seeds, also known as Iridium-192, are a form of high-dose-rate (HDR) brachytherapy used in cancer treatment. These seeds are temporarily placed directly into or near tumor sites to target and kill cancer cells while minimizing damage to surrounding healthy tissue. They are utilized for various types of cancer, including breast, prostate, cervical, endometrial, gynecologic, skin, head and neck, esophageal, lung, and rectal cancers. The procedure is designed to provide effective local treatment, often allowing patients to receive care on an outpatient basis with shorter treatment times and fewer side effects compared to traditional radiation methods.
Before treatment, patients undergo imaging studies to determine the optimal placement of the seeds, and may have additional tests such as blood work. The procedure typically involves numbing the area or using general anesthesia, followed by the insertion of a catheter through which the seeds are delivered using a specialized machine. After the treatment, the catheters are removed, and patients typically do not retain radiation, allowing them to safely be around others. While the side effects can vary depending on the treatment area, they are generally manageable, and studies indicate that iridium seeds are as effective as other prostate cancer treatments, with promising results for other cancers as well.
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Iridium seeds
ALSO KNOWN AS: Iridium 192, high-dose-rate (HDR) or temporary brachytherapy
DEFINITION: Iridium seeds are high-dose radiation sources temporarily placed into a tumor site to stop the growth of cancer cells or to relieve symptoms without damaging normal tissue.
Cancers treated: Breast, prostate, cervical, endometrial, gynecologic, skin, head and neck, esophageal, lung, rectal, and other cancers
Why performed: Internal radiation used to kill cancer cells at the site of a tumor provides effective local cell death and discourages regrowth. Using iridium seeds delivers a higher dose of radiation directly to the tumor, protects normal tissue, and allows outpatient care with shorter, more comfortable treatments and fewer side effects.
Patient preparation: Before the procedure, patients will have imaging studies such as X-rays, a computed tomography (CT) scan, ultrasound, or magnetic resonance imaging (MRI) to decide where the iridium seeds should be placed to work best. Patients may have other tests such as blood work or electrocardiography (EKG). If seeds are to be placed in the prostate, then an enema and bowel cleansing routine is used. Some sites require only local anesthesia, while others may require general anesthesia and surgery. Patients should receive clear directions from a doctor or nurse based on the site of treatment before the procedure.
Steps of the procedure: A treatment plan is developed by the doctor and the radiation therapy staff. A needle, catheter, or balloon catheter is placed in the site when patients are either asleep or the area has been numbed to ensure that there is no pain. An iridium seed is sent through the catheter by a computerized machine called a high-dose remote afterloader; it is left in the tumor for a few minutes and then removed. Treatments can be once or twice a day, and the number varies by site.
After the procedure: Once all treatments are complete, the catheters will be removed gently, usually without difficulty or discomfort. It is safe for patients to be around others, including children and pregnant women, because no radiation remains in the body.
Risks: The side effects depend on the site treated but may include urinary symptoms, rectal symptoms, fatigue, eating problems, shortness of breath, pain, redness, and swelling.
Results: Iridium seeds for high-dose brachytherapy appear to be as effective as other methods of prostate cancer treatment. They are often used to treat cervical and endometrial cancers. Their use in the treatment of breast cancer began in the 1990s and is effective in treating stages 1 and 2 of the disease. Other diseases report equally effective results with good local control as compared to other treatments.
Bibliography
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“Definition of Iridium Ir 192 - NCI Drug Dictionary.” National Cancer Institute, www.cancer.gov/publications/dictionaries/cancer-drug/def/iridium-ir-192. Accessed 16 June 2024.
Herndon, Jaime R. “Brachytherapy for Early-Stage Breast Cancer.” Verywell Health, 24 May 2022, www.verywellhealth.com/brachytherapy-430387. Accessed 16 June 2024.
“High Dose Rate (HDR) Brachytherapy.” Brigham and Women's Hospital, www.brighamandwomens.org/radiation-oncology/brachytherapy. Accessed 16 June 2024.
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Odunsi, Kunie, and Tanja Pejovic. Gynecologic Cancers: A Multidisciplinary Approach to Diagnosis and Management. New York: Demos Medical, 2013.
Venselaar, Jack. Comprehensive Brachytherapy: Physical and Clinical Aspects. Boca Raton: CRC, 2013.