Final answer:
Brachytherapy is the process of implanting radioactive pellets or seeds directly into a tumor to provide internal radiation treatment, commonly used for cancer treatment like prostate cancer.
Step-by-step explanation:
The implantation of radioactive pellets directly into a tumor is known as brachytherapy, which is a form of internal radiation therapy. During brachytherapy, ionizing pellets (also referred to as seeds) or rods are placed directly at the site of the tumor. These pellets produce photons in the form of x-rays or gamma rays internally, thus localizing the radiation to the tumor. The radioactive seeds, which are surgically implanted, can come in the form of titanium capsules and contain isotopes like iodine-125, palladium-103, or cesium-131 with short half-lives. This method delivers a high dosage of radiation to the tumor over a short period and is a common treatment for conditions such as prostate cancer, with seeds approximately the size of a grain of rice. Figure 8.6.7 illustrates the small size of these seeds compared to an American penny and their application in prostate cancer treatment.