Final answer:
Internal radiation therapy, known as brachytherapy, is a cancer treatment where radioactive substances are introduced into the body to concentrate in a specific organ or tissue, thereby killing cancer cells or preventing them from dividing. It can involve permanent or temporary implants of ionizing pellets or rods to deliver localized internal radiation.
Step-by-step explanation:
Internal radiation therapy, also known as brachytherapy, is a form of treatment where radiation from a radioactive substance is introduced into the body to kill cancer cells. This method is used when a radioisotope can selectively concentrate in the targeted organ or tissue. For instance, iodine-131, which is a beta and gamma emitter, is used to treat hyperthyroidism by being absorbed by the thyroid gland. Similarly, actinium-225, an alpha emitter with a half-life of 10 days, can be bonded to a monoclonal antibody that targets prostate-specific antigens to treat prostate tumors.
Brachytherapy involves inserting ionizing pellets or rods directly into the tumor area. These implants can either stay permanently or be placed temporarily to deliver localized radiation inside the body. When using pellets, patients remain radioactive for as long as the pellets are inside, whereas temporary rods emit radiation immediately without leaving residual radioactivity.
As a form of radiation therapy, brachytherapy aims to damage the DNA of cancer cells, causing cell death or preventing cell division. This type of therapy can be an alternative to external beam radiation therapy, which is delivered by a machine from outside the body. The therapeutic use of radioisotopes in higher doses is a crucial component of treating various types of cancers.