Types of Radiation Therapy
Radiation therapy can be delivered in two ways, externally or internally. During external beam radiation, the radiation oncology team uses a machine called a linear accelerator to direct high energy X-rays at the cancer. Internal radiation or brachytherapy involves placing the radiation sources (for example, radioactive seeds) inside the tumor.
External Beam Radiation Therapy:
Linear Accelerator Therapy
The Radiation Oncology Department provides two high energy linear accelerators which allow the production of high energy X-rays as well as electron beam radiation. By having two machines, this allows for convenient scheduling of our patients. Both machines offer the capabilities of intensity modulated radiation which is an extremely precise means of delivering radiation.
Intensity Modulated Radiation Therapy (IMRT)
IMRT allows the delivery of extremely precise doses of radiation that can destroy the cancer cells while allowing better sparing of the surrounding normal and healthy tissues. This involves a very special type of radiation treatment planning to calculate the doses of radiation.
Brachytherapy:
High Dose Rate Brachytherapy (HDR)
HDR uses a small radioactive iridium source on the end of a computer controlled flexible wire. The radiation is delivered through narrow tubes, called catheters, into the tumor. The tubes remain in place for only a very short time and then are removed. Once the treatment is complete, the patient is discharged the same day. After this type of radiation, no special precautions regarding radiation exposure to others are necessary. This form of therapy is used in the treatment of certain cases of lung, breast and cervix cancer.
Mammosite Radiation Therapy
This form of therapy uses the High Dose Rate (HDR) form of radiation to treat breast cancer after the primary tumor has been removed. A flexible plastic tube called a Mammosite catheter or balloon is inserted into the cavity where the original cancer was removed. Treatment is given twice a day for five days. The Mammosite catheter is connected to the HDR machine which then uses a special computer to direct the small radioactive source into the catheter. This remains in place for only a few minutes and is then removed. After the end of five days of treatment the catheter is removed.
Gliasite Radiation Therapy
This form of brachytherapy uses a special inflatable catheter or balloon which is placed into the cavity where the original primary or metastatic brain tumor was removed. A portion of the catheter is placed directly beneath the skin. Using a small needle inserted through the skin into the catheter, a liquid form of radioactive iodine is then injected into the catheter. This remains in place for four to five days and is then removed.
Prostate Seed Implant
This form of therapy uses special radioactive pellets or seeds of radioactive material which are placed into the prostate under anesthesia. The seeds are temporarily radioactive and deliver the radiation to the prostate cancer over several months. After losing their radioactivity, the seeds remain in the prostate and are harmless.
CT Simulation and Computerized Treatment Planning
To be most effective, radiation must be aimed precisely at the target each and every time treatment is given. The process of measuring your body and marking your skin to help your treatment team direct the beams of radiation safely and exactly to the intended locations is called simulation. At the Trinity Radiation Oncology department, a special CT scan is performed to precisely determine the position and extent of the cancer and the other normal and healthy tissues. This is used with a sophisticated treatment planning computer to calculate the doses of radiation to produce the best possible treatment plan. |
