What is Radiation Therapy?
Radiation therapy uses a stream of high-energy particles or waves, such as x-rays, gamma rays, electrons, or protons to destroy or damage cancer cells.
Radiation therapy is one of the most common treatments for cancer and is used in more than half of all cancer cases. It is often part of the main treatment for some types of cancer, such as cancers of the head and neck, bladder, lung and Hodgkin’s disease. Many other cancers are also treated with radiation therapy. Thousands of people become free of cancer after receiving radiation treatments alone or in combination with surgery, chemotherapy, or immunotherapy (biologic therapy).
How does it work?
All cells, cancerous and healthy, grow and divide. But cancer cells grow and divide more rapidly than many of the normal cells around them. Radiation therapy uses special equipment to deliver high doses of radiation to cancerous tumors, killing or damaging them so they cannot grow, multiply, or spread. It works by breaking a strand of the DNA molecule inside the cancer cell, which prevents the cell from growing and dividing. Although some normal cells may be affected by radiation, most recover fully from the effects of the treatment.
What is IMRT?
IMRT (intensity modulated radiation therapy) is a relatively new technique to improve external delivery of radiation therapy by a linear accelerator. Intensity modulated radiation therapy (IMRT) is a method that allows the strength of the beam to be changed to lessen damage to normal body tissues. This technique allows for the doctor to change the intensity of the radiation within each beam to safely increase the amount of radiation delivered to the prostate. This technique can be further enhanced by adding visualization of the prostate anatomy before each daily treatment, called Image Guided Raditaion Therapy or IGRT.
Unlike chemotherapy, which exposes the entire body to cancer-fighting chemicals, IMRT/IGRT is a state-of-the-art local treatment that only affects the part of the body being treated.
How does IMRT work?
Instead of maintaining a uniform radiation beam as used in conventional or 3-dimensional radiation therapy, IMRT uses devices within the linear accelerator to divide the radiation beam into multiple smaller beams called beamlets that can have different intensities (modulated) within the area being treated. This allows more precise delivery of radiation doses to the tissues within the target area, allowing increased doses to the prostate while relatively sparing the surrounding bladder and rectum. This is important as several recent medical studies have suggested that higher prostate doses are associated with increased curability. IMRT is delivered or given by a machine called a linear accelerator. The machine directs high-energy x-rays at the cancer and some normal surrounding tissue from outside the body. Patients receive IMRT during outpatient visits to a hospital or treatment center. IMRT involves a series of daily treatments to target and accurately deliver radiation to the prostate.
Frequently Asked Questions
IMRT (Intensity Modulated Radiation Therapy) How does it work?
What is IGRT?
IGRT is the process of imaging the location of the patient’s organ/tumor on a daily basis and comparing the tumor’s current location to the location the organ/tumor was on the day the CT for the radiation treatment plan was completed. IGRT requires your urologist to place 2 fiduciary markers in the prostatic area which are visualized and tracked daily.
Example: The prostate often will move in excess of 1 cm in any direction based on the content of the patient’s bladder and bowels. With IGRT, we track the exact location of the markers within the prostate and compensate for the change in position on a daily basis.
IGRT is very important when using IMRT because this technology allows us to decrease the margin we treat around the tumor to 5mm or less. This precision of the exact position of the organ/tumor allows the application of IMRT to be even more effective. Image Guided Radiation Therapy (IGRT) in combination with Intensity Modulated Radiation Therapy (IMRT) is the most advanced treatment delivery technique today. On a daily basis, IGRT identifies the prostatic area and the normal structures in the area of treatment. A CT scan of the prostatic area is obtained daily to overlap and match the fiducial markers for positioning and treatment.