Radiation Therapy
Radiation therapy uses high doses of ionizing radiation to kill cancer cells or slow their growth by damaging their DNA. Cells whose DNA is damaged beyond repair stop dividing or die, so the effect builds up gradually over days to weeks of treatment rather than immediately. Depending on the clinical situation, radiation can be delivered from outside the body (external beam therapy), from sealed sources placed in or next to the tumor (brachytherapy), or as radioactive drugs that travel through the bloodstream (radiopharmaceuticals). It may be given with the aim of curing cancer, lowering the risk of recurrence, or relieving symptoms such as pain. Because radiation also affects nearby healthy cells, treatment is carefully planned to spare them, and each area of the body has a lifetime limit on the dose it can safely receive.
External Beam Radiation Therapy (EBRT)
External beam radiation therapy delivers precisely aimed radiation to the tumor from a machine outside the body and is the most widely used form of radiation treatment. Modern techniques such as IMRT shape the dose to th…
Brachytherapy (Internal Radiation Therapy)
Brachytherapy places a sealed radiation source — seeds, ribbons, or capsules — directly in or next to the tumor, so a high dose is delivered exactly where it is needed while the intensity falls off quickly in surrounding…
Proton Therapy
Proton therapy is a form of external beam radiation that uses accelerated protons instead of x-rays; protons release most of their energy at a set depth and then stop, so tissue beyond the tumor receives very little dose…
Radiopharmaceuticals (Radionuclide Therapy)
Radiopharmaceuticals are radioactive drugs given by mouth or into a vein that travel through the bloodstream and deliver radiation directly to cancer cells throughout the body. The oldest example is radioactive iodine (I…