The CyberKnife system is exceptionally accurate because of two key advancements:
1.) A robotic arm which can point the radiation treatment at the patientís tumor from a wide variety of angles. In fact, the CyberKnife can irradiate the tumor from over 1200 angles. The tumor is hit from multiple angles many times, so that the cumulative radiation dose is much more intense than standard radiation therapy.
2.) Multiple x-ray and stereoscopic video cameras which when combined with powerful tracking software are able to localize the tumors position. The cameras obtain frequent pictures of the patient during treatment, and use this information to target the radiation beam emitted by the linear accelerator. This enables CyberKnife to precisely treat tumors that move with respiration, such as lung cancers.
Radiation therapy, also called radiotherapy or irradiation, is the use of a certain type of energy (called ionizing radiation) to kill cancer cells and shrink tumors. Radiation therapy selectively injures or destroys tumor cells in the area being treated, by damaging their genetic material, making it impossible for these cells to continue to grow and divide. Although radiation damages both cancer cells and normal cells, most normal cells can recover from the effects of radiation and function properly.
In some cases, the goal of radiation treatment is the complete destruction of an entire tumor. In other cases, the aim is to shrink a tumor and relieve symptoms. In either case, doctors plan treatment to spare as much healthy tissue as possible.
There are different types of radiation and different ways to deliver the radiation.
What is the difference between external radiation therapy, internal radiation therapy (brachytherapy), and systemic radiation therapy? When are these types used?
Radiation may come from a machine outside the body (external radiation), may be placed inside the body (internal radiation), or may use unsealed radioactive materials that go throughout the body (systemic radiation therapy). The type of radiation to be given depends on the type of cancer, its location, how far into the body the radiation will need to go, the patient's general health and medical history, whether the patient will have other types of cancer treatment, and other factors.
In conjunction with the Cancer Center of Acadiana, Lafayette General Radiation Oncology offers:
External radiation therapy utilizing intensity modulated radiation therapy (IMRT). Two photon linear accelerators are equipped with 120 individual 'leaves' that can conform the shape of the radiation beam to the shape of a tumor from any angle. In fact, IMRT can deliver beams the size of a pencil tip, sparing normal tissue and resulting in fewer side effects.
Internal radiation therapy (also called brachytherapy) uses radiation that is placed very close to or inside the tumor. The radiation source is usually sealed in a small holder called an implant. Implants may be in the form of thin wires, plastic tubes called catheters, ribbons, capsules, or seeds. Three examples include:
High dose seeds implanted in the prostate gland, to treat prostate cancer
Mammosite, which places a seed within a balloon into the site of the lumpectomy for five days of targeted radiation.
HDR treatment to gynecologic malignancies including cervical and uterine cancer.
Systemic radiation therapy uses radioactive materials such as iodine 131 and strontium 89. The materials may be taken by mouth or injected into the body. Systemic radiation therapy is sometimes used to treat cancer of the thyroid, hormone refractory metastatic prostate cancer and adult non-Hodgkin lymphoma. Researchers are investigating agents to treat other types of cancer.
What are stereotactic radiosurgery and stereotactic radiotherapy?
Stereotactic (or stereotaxic) radiosurgery uses a single large dose of radiation to destroy tumors in the brain or the body. The procedure does not involve actual surgery. The dose and area receiving the radiation are delivered with extremely high precision. Most nearby tissues are not damaged by this procedure.
Stereotactic radiotherapy uses essentially the same approach as stereotactic radiosurgery to deliver radiation to the target tissue. However, stereotactic radiotherapy uses multiple radiation treatments between 2 to 5 daily treatments. Giving multiple smaller doses may improve outcomes and minimize side effects.
Stereotactic radiotherapy is used to treat tumors in the brain as well as other parts of the body.
General information courtesy of: The Web site of the National Cancer Institute (http://www.cancer.gov)