Radiation Therapy Overview:
Radiation therapy is an effective cancer treatment because it works by damaging cells – normal cells are able to repair themselves, but cancer cells can’t repair the damage and die. Many types of cancer can be treated with radiation therapy. Corpus Christi Cancer Center uses a state of the art Varian linear accelerator, which allows us to more precisely target tumors while sparing healthy tissue. Our radiation oncology services include:
- Intensity modulated radiation therapy (IMRT)
- Low Dose Brachytherapy (permanent implantation of low-dose radioactive materials within the body)
Radiation therapy effectively treats many types of cancer, some of which include breast, colorectal, head and neck, prostate and gynecologic. In addition, radiation therapy may also be used to shrink tumors to reduce pain in patients with advanced cancers.
Radiation therapy can be useful in the treatment of cancer in several ways:
- Sometimes, radiation therapy is the only treatment that is needed. For example, many prostate cancer patients are treated with radiation therapy alone.
- Radiation therapy can also be used in conjunction with other treatments, either before or after. For example, radiation may be used before surgery to shrink the tumor so the surgery will be less extensive, but radiation therapy can also be used after surgery to destroy any cancer cells that may have remained.
- For advanced cancer, radiation therapy can be used to slow tumor growth or shrink tumors that interfere with body functions or cause pain (for example, a lung tumor that is making it difficult for a patient to breathe). This type of treatment will not cure the cancer, but may help improve the patient’s quality of life.
Types of treatment:
The ultimate goal of radiation therapy is to use enough radiation to kill the cancer cells while minimizing damage to healthy tissue. Radiation therapy can be delivered either internally or externally. Depending on the location of your cancer, its size and type, you may receive either or both methods of treatment. If external beam radiation therapy is used, a machine will direct radiation at the cancer – much like a routine x-ray. Internal radiation, or brachytherapy, on the other hand, inserts radioactive materials, such as seeds, into your body.
External Beam Radiation Therapy
When you are given external beam radiation therapy, the radiation beam is focused on the part of the body where the cancer is to destroy the main tumor and any nearby cancer cells. To minimize side effects, treatments are usually given five days a week, Monday through Friday, for up to seven or eight weeks. This schedule allows enough radiation to get into your body to kill the cancer while giving your healthy cells time to recover.
Our radiation beam is generated by a machine called a linear accelerator. The linear accelerator, or linac, produces high-energy X-rays and electrons to treat your cancer. Your treatment team uses complex treatment planning software to pinpoint the treatment site and plan the size, shape and direction of the beam to best treat your cancer while protecting the surrounding normal tissue.
Several special types of external beam therapy are discussed in the next sections. These are used for specific types of cancer, and your radiation oncologist will recommend one of these treatments if he or she believes it will help you.
Three-Dimensional Conformal Radiation Therapy (3D-CRT)
Tumors come in different shapes and sizes. Three-dimensional conformal radiation therapy, or 3D-CRT, uses computers and special imaging to help pinpoint the size, shape and location of the tumor. Using computer assisted tomography (CT scans), magnetic resonance imaging (MRI scans) and/or positron emission tomography (PET scans), the Dosimetrist creates a treatment plan from detailed, three-dimensional representations of the tumor and surrounding organs. Your Radiation Oncologist then precisely tailors the radiation beams to your tumor with custom fabricated field shaping blocks. Because the radiation beams are so precisely directed, nearby normal tissue receives less radiation and is able to heal quickly.
Intensity Modulated Radiation Therapy (IMRT)
Intensity modulated radiation therapy, or IMRT, is a more advanced form of 3D-CRT that allows the radiation beams to be more precisely shaped to fit the tumor. With IMRT, the beam can be broken into many smaller beams and the intensity of each smaller beam can be adjusted individually. IMRT may help to further limit the radiation that affects healthy tissue near the tumor. In some cases, this may also permit higher doses of radiation to be delivered to the tumor, potentially increasing the chance for a cure.
Brachytherapy Treatments
Brachytherapy is internal radiation therapy, placing radioactive materials in or next to the tumor. In this type of treatment, the radioactive materials may be left in place permanently or temporarily, depending upon your cancer.
There are two main types of brachytherapy — intracavitary treatments and interstitial treatments. In intracavitary treatment, the radioactive materials are put into a space near where the tumor is located, such as the cervix or the windpipe. In interstitial treatment, the radioactive materials are put directly into the tissues, such as the prostate.
Depending on the kind of brachytherapy treatment you were given, you may need to take some precautions for a short period of time after your treatment, especially if you might be around small children or pregnant women. Ask your treatment team if these precautions apply to you.