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Radiation Therapy | 810-985-1484

Linear Accelerator
St. Joseph Mercy Cancer Center's Radiation Therapy Linear Accelerator

Frequently Asked Questions

How does radiation therapy work?

Cancer cells grow and divide more rapidly than many of the normal cells around them. High doses of radiation can kill cells or keep them from growing and dividing, and it has proven to be particularly effective in killing cancer cells and shrinking tumors. Although some normal cells are affected by radiation, most normal cells recover more fully from the effects of radiation than do 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 as therapy for cancer. It is a form of radiation therapy that uses computer-generated images to plan and then deliver tightly focused radiation beams to cancerous tumors than is possible with conventional radiotherapy. With this capability, clinicians can deliver a precise radiation dose that conforms to the shape of the tumor, while significantly reducing the amount of radiation to surrounding healthy tissues. Consequently, the technique can increase the rate of tumor control while significantly reducing adverse side effects.

Why would I want to be treated with IMRT?

St. Joseph Mercy Cancer Center's linear accelerator is use to generate high does of radiation to kill cancer cells. With SmartBeam IMRT, clinicians can deliver more tightly focused beams to the cancerous tumors.

IMRT is one of the most precise forms of radiation therapy available. It allows physicians to escalate the radiation dose to cancer cells, and in some cases, even more precisely to specific metabolically active regions within a tumor, while keeping the dose to surrounding tissues as low as possible.

What forms of cancer are frequently treated with IMRT?
IMRT is most successful in the treatment of some forms of prostate, esophageal and head and neck cancers. It is not generally used, nor recommended in the radiation therapy treatment of all forms of cancer. Traditional forms of radiation therapy, utilizing St. Joseph Mercy Cancer Center's advanced linear accelerator, successfully provide results for those cancers that do not qualify for IMRT use. Your Radiation Oncologist will provide you with the most beneficial treatment option.

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. The idea is to deliver the lowest dose possible to the surrounding tissue, reducing the chance of causing a radiation side effect, while still delivering the maximum dose to the tumor.

Does radiation therapy expose people to radioactive substances?

Many people, when they hear the word "radiation," think immediately of radioactive substances. 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 - none is "stored" or "transported."

With SmartBeam IMRT, the tumor can be precisely targeted for higher doses of radiation, sparing healthy tissue unnecessary exposure.

What happens when a person is treated with SmartBeam IMRT?

SmartBeam IMRT treatment involves three basic steps: diagnosis, treatment planning and delivery. As part of diagnosis, physicians generate three-dimensional diagnostic images (usually CT or MRI) of the patient's anatomy and uses these to specify the dose of radiation each area will receive. Treatment planning includes a simulation session to further localize the cancer and finalize the radiation treatment plan.

Patients receive the SmartBeam IMRT treatment according to various schedules, usually five days a week for six or seven weeks. Each treatment takes ten to fifteen minutes.

What is the IMRT process like?

The IMRT process is similar to a typical radiation treatment. Typically, after conducting a physical exam and a medical history review, the radiation oncologist determines an individualized course of treatment for each patient.

Treatment Preparation
Most cases require a treatment preparation session, which is called a simulation. Special molded devices that help the patient maintain the same position every day are sometimes developed at this point. Marks are placed on the patient's skin, to assist in aligning the radiation equipment with the target area. The treatment preparation session takes from thirty minutes to an hour and involves a CT scan.

Following the CT scan, the IMRT planning process usually takes several days. When the plan is complete, the patient is given an appointment to begin radiation treatments.

St. Joseph Mercy Cancer Center's linear accelerator utilize a multileaf collimator to shape the radiation beam in accordance with the best treatment planning.

Treatment Delivery
The first IMRT treatment session is sometimes longer than subsequent ones so that additional X-ray films and checks can be done. A typical IMRT treatment session lasts about 15 minutes.

In the treatment room, the radiation therapists use 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 therapists leave the treatment room before the machine is turned on. The machine is controlled from a nearby area. The patient can be seen on a television screen in the control room. The therapists can talk with the patient through an intercom. Patients do not see or hear the radiation and do not feel anything. If a patient becomes uncomfortable, however, the machine can be stopped at any time.

Who gives the treatment?

A doctor who has had special training in using radiation to treat disease - a radiation oncologist - prescribes the type and amount of treatment that best suits a particular patient's needs. The radiation oncologist works closely with other doctors and also heads a highly trained health care team. This team 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 how to manage any side effects, and 4) radiation therapists set the patient up for treatment and run the equipment that delivers the radiation.

How Long Is a Course of IMRT Treatment?

Radiation therapy usually is given five days a week for six or seven weeks. For each radiation therapy session, the patient is in the treatment room for about 10 to 20 minutes. These types of schedules, which use 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. Patients need not 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 of radiation therapy most often are related to the area that is being treated. Most side effects that occur during radiation therapy, 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, as of January 1, 2001, Medicare will provide 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 the hospital business office about your policy and how expected costs will be paid.

To find out more, talk to your doctor about a referral to the St. Joseph Mercy Hospital Radiation Therapy service, brought to you by the St. Joseph Mercy Cancer Center.

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St. Joseph Mercy Port Huron | 2601 Electric Avenue, Port Huron, Michigan 48060 | 810-985-1500