Frequently Asked Questions
For specific questions you may have about the equipment or about Radiation Therapy, contact your doctor or our Radiation Oncology department. However, below are the answers to some of the questions several people have about IMRT/IGRT.
How does radiation therapy work?
Cancer cells grow and divide faster than normal cells around them. High doses of radiation can kill cells or keep them from growing and dividing. Radiation is particularly effective in killing cancer cells and shrinking tumors. Although some normal cells are affected by radiation, most normal cells recover more fully from radiation than cancer cells.
What is IMRT (Intensity Modulated Radiation Therapy)?
SmartBeam IMRT involves varying (or modulating) the intensity of the radiation (in this case, X-rays), being used on tumors. It uses computer-generated images to plan, and then deliver, radiation beams that are more tightly focused. This allows a dose that actually conforms to the shape of the tumor and significantly reduces the amount of radiation to surrounding healthy tissue. That, in turn, reduces many side effects. In some cases IMRT treatment can be a non-invasive alternative to surgery.
For example, in the case of head and neck tumors, IMRT can minimize exposure of the spinal cord, optic nerve, salivary glands, and other important structures.
How is SmartBeam IMRT different?
The main advantages are precision and speed.
This system achieves a very high resolution, which maximizes the sparing of surrounding tissue. A computerized tool called a multileaf collimator (MLC) shapes the beam in accordance with the optimized treatment plan.
In addition, the SmartBeam IMRT is fast. The patient is only positioned once per session, rather than multiple times. The multileaf collimator eliminates the need for clinicians to keep going in and out of the treatment room to insert and remove lead blocks that shape the beam.
Why would I want to be treated with IMRT?
IMRT is the most precise form of radiation therapy available. It allows physicians to increase the radiation dose to cancer cells, and in some cases, even deliver it to specific active regions within a tumor, while keeping the dose to surrounding tissues low. Think of it as painting with a paintbrush, versus using an airbrush and masking tape to protect outlying areas. The airbrush allows you to use variable amounts of paint in a highly controlled fashion. IMRT does something similar with radiation.
What kind of radiation is used in IMRT?
Currently, photons (X-rays) are used to deliver IMRT. The radiation is generated by a machine called a medical linear accelerator. This machine stands approximately nine feet tall, is nearly 15 feet long and can be rotated around the patient with great precision. Operationally, microwave energy, similar to that used in satellite television transmission, is used to accelerate electrons to nearly the speed of light. As they reach maximum speed they collide with a tungsten target, which in turn releases photons, or X-rays.
Very small beams with varying intensities can be aimed at a tumor from various angles to attack the target in a complete three-dimensional manner. In fact, SmartBeam IMRT can be delivered with beams the size of 2.5 x 5-millimeter pixels—the size of a pencil tip—each with varying intensity. The idea is to deliver the lowest dose possible to the surrounding tissue, reducing side effects, while still delivering the maximum dose to the tumor.
Does radiation therapy expose you to radioactive substances?
When many people hear the word “radiation” they immediately think of radioactivity. However, no radioactive substances are involved in the creation of X-rays or electrons by a medical linear accelerator. When a linear accelerator is switched on, radiation is produced and aimed directly at cancer cells. Then, like a flashlight, when the machine is switched off, there is no more radiation.
What happens when a person is treated with IMRT?
SmartBeam IMRT treatment involves three steps: diagnosis, treatment planning, and delivery. As part of diagnosis, physicians generate three-dimensional diagnostic images (usually CT or MRI) and use them to specify the dose of radiation each area will receive. Patients receive the treatment according to their particular schedule, usually five days a week for six or seven weeks. Each treatment takes 10 to 15 minutes.
Treatment Preparation
Most cases require a treatment preparation session. Special molded devices that help the patient maintain the same position every day are sometimes developed. Colored, semi-permanent ink is often used to mark the patient’s skin, to help align the radiation equipment with the target area. X-rays may be taken to help prepare for a CT scan that will be used in planning the treatment. The treatment preparation session might take from 30 minutes to an hour and the CT scan may take an additional 15-30 minutes. Then it takes a few days for the doctor to create the treatment plan. When the plan is finished, an appointment is made for the patient to begin treatments.
Treatment Delivery
The first IMRT treatment session is sometimes longer than other ones so additional X-ray films and checks can be done. But a typical IMRT treatment session lasts about 15 minutes.
In the treatment room, the radiation therapist uses the marks on the patient’s skin to locate the treatment area. The patient is positioned on a treatment table. Sometimes special molded devices are used to help with positioning. Receiving external radiation treatments is painless, just like having an X-ray taken.
The radiation therapist leaves the treatment room before the machine is turned on and goes to the control room. From there, the patient can be seen on a television screen or through a window and can talk with the therapist over an intercom. Patients do not see or hear the radiation and usually do not feel anything. If a patient becomes uncomfortable, however, the machine can be stopped at any time.
Who gives the treatment?
A doctor with special training in the use of radiation to treat disease -- a radiation oncologist -- prescribes the type and amount of treatment that best suits a particular patient. The radiation oncologist works closely with other doctors and also heads team that often includes:
1) a radiation physicist, who participates in the planning process and ensures that the machines deliver the right dose of radiation,
2) a dosimetrist, who plans the treatment with the oncologist and the physicist,
3) a radiation therapy nurse, who provides nursing care and helps patients learn about treatment and managing any side effects, and
4) a radiation therapist, who sets the patient up for treatment and runs the equipment that delivers the radiation.
How Long Is a Course of IMRT Treatment?
Radiation therapy is usually given five days a week for six or seven weeks. When radiation is used for palliative care, treatment that eases symptoms, the treatment lasts two to three weeks. During each session, the patient is in the treatment room around 15 to 30 minutes. These schedules, which dispense small amounts of daily radiation rather than a few large doses, help protect normal body tissues in the treatment area. Weekend rest breaks allow normal cells to recover. The total dose of radiation and the number of treatments a patient needs depend on the size and location of the cancer, the type of tumor, the patient’s general health, and other factors.
What Are the Effects of Treatment?
External radiation therapy does not cause a patient’s body to become radioactive. Don’t avoid being with other people because of treatment. Even hugging, kissing, or having sexual relations with others poses no risk to them of radiation exposure.
Side effects most often are related to the area being treated. Most side effects that occur, although unpleasant, are not serious and can be controlled with medication or diet. They usually go away within a few weeks after treatment ends. With SmartBeam IMRT, some patients have no side effects at all.
Is IMRT Expensive?
Treatment of cancer with radiation can be costly. It requires very complex equipment and the services of many health care professionals. The exact cost of your radiation therapy will depend on the type and number of treatments you need.
Fortunately, Medicare provides additional reimbursement for IMRT treatments given by a hospital outpatient department. Many health insurance policies cover charges for radiation therapy. It's a good idea to talk with your insurer, your doctor's office staff, or our business office.