More than half of all cancer patients will have some type of radiation therapy as part of their cancer care.
Radiation therapy, also called radiotherapy, uses beams of intense energy to destroy cancer cells by damaging their DNA. Because radiation can also harm healthy cells, treatment must be carefully planned and precisely conducted to target the cancer and minimize the effect on healthy cells.
Radiation therapy may be given before, during, or after other cancer therapies in your treatment plan, and for various reasons. It may be used alone or with other treatments to:
- Eliminate tumors
- Reduce risk for cancer recurrence after undergoing surgery or chemotherapy
- Shrink a tumor before surgery
- Relieve pain, breathing difficulty or other symptoms by reducing the size of a tumor
- Treat cancer in a bone
The Radiation Medicine team plans your treatment carefully choosing:
- The type of radiation therapy
- The dose of energy to be delivered (how much, over how many treatments)
- The area to be radiated
Types of radiation therapy
Radiation therapy may be delivered from outside or inside your body. External radiation uses a large machine outside the body to generate the radiation and direct it toward the site of the cancer. Internal radiation places the radiation inside your body in or near the cancer. Some patients may have both types of radiation therapy.
External beam radiation therapy types
The most common type of radiation therapy for cancer — external beam radiation therapy — uses a machine called a linear accelerator (or linac) to generate the high-energy radiation beams that are directed to your cancer to destroy the tumor and nearby cancer cells. Roswell Park uses several types of external beam radiation therapy:
Using the latest technologies available in linear accelerators with sophisticated computer software systems, 3D-CRT delivers accurate radiation to very precisely-shaped target areas. 3D-CRT has become the new standard in radiation therapy, combining modern imaging such as computer tomography (CT) and magnetic resonance imaging (MRI) with the planning software.
Intensity modulated radiation therapy (IMRT) delivers a single dose of radiation with the aid of hundreds of tiny beam shaping devices (called collimators. The treatment team can move the collimators to sculpt the radiation beams to the shape of the tumor and treat the tumor from various angles. As the collimators move and shape the beam, radiation intensity can vary or modulate, allowing different areas of the tumor or nearby tissues to receive different doses of radiation.
This type of radiation therapy uses repeating imaging scans (CT, MRI, or PET) taken during treatment to identify changes in the tumor’s size or location during treatment. Patient position and/or radiation dose can be recalculated as needed during treatment.
Gamma Knife radiosurgery isn’t a knife at all, but a type of extremely precise and sharply focused type of advanced radiation therapy that treats brain tumors, lesions and other brain disorders. The precision of the radiation is “surgical” but there’s no cutting, no incisions and no need for anesthesia. A pioneer in Gamma Knife radiosurgery, Roswell Park is the only facility in the region with the expertise and experience to offer this advanced treatment.
This type of radiation therapy uses special equipment to position the patient and deliver a very high dose of radiation to tumors in the body (except the brain) over 1 to 3 treatment sessions. The equipment helps account for tumor movement with body movement, such as breathing. Also called stereotactic ablative radiotherapy (SBAT) or stereotactic body radiation therapy (SBRT) the treatment may be used for some lung and liver tumors, even in patients who cannot undergo surgery.
Total body irradiation (TBI) is a technique used to deliver irradiation to the entire body. TBI is part of a complex treatment program for certain conditions and can be combined with high-dose chemotherapy in preparation for stem cell transplantation.
Volumetric modulated arc therapy (VMAT) is a more precise form of external radiation than 3D-CRT, in that the radiation dose and the field shape is changed or modulated as the treatment machine moves or arcs around the patient. This treatment helps spare more normal tissue.
Internal radiation therapies
Radiation that’s given inside your body uses small implants, such as seeds, beads, pellets, other substances that contain radioactive material. The implants are placed within or near the tumor and emit radiation to the surrounding tissue. Internal radiation types include:
Brachytherapy uses radioactive isotopes sealed into tiny seeds or pellets and placed within the tumor tissue (also called interstitial brachytherapy). This treatment is often used for prostate cancer, or in a body cavity or surgical cavity near the tumor (called intracavity brachytherapy). The radioactive implant may be temporary or permanent (radiation eventually wears off) and brachytherapy treatment may be either:
- High-dose rate brachytherapy - uses one very small high radiation implant that is inserted temporarily, from minutes to hours. Treatments are given in separate sessions about six hours apart.
- Low-dose rate brachytherapy - allows continuous low-dose radiation to a treatment area over a period of several days
With selective internal radiation therapy, a catheter is inserted into the artery leading to the tumor. Radioactive microbeads are released through the catheter directly to the tumor where they collect and deliver a radiation dose to the tumor, with little radiation reaching adjacent tissues. This approach delivers higher radiation doses to a tumor and results in fewer side effects to nearby tissues and organs than is possible with external beam radiation therapy.
With systemic radiation therapy, the radiation goes through your whole-body system. For this type of therapy, you would swallow, or receive an injection of a radioactive substance. One type of this therapy uses radioactive iodine for the treatment of thyroid cancer. Thyroid cells naturally take up the iodine, concentrating the radiation in the thyroid gland. Other forms bind the radioactive substance to a targeted therapy drug to seek out and attach to specific cancer cell types, such as B-cell non-Hodgkin lymphoma (NHL).
A type of systemic radiation therapy — called Theranostics — is a rapidly growing front in the fight against cancer as recent breakthroughs have led to new drugs to selectively target cancer cells and carry radioactive particles to the cells. Roswell Park’s new Theranostics Center significantly expanded the number of patients we can serve with these innovative treatments.