Radiation Oncology – A Guide for Patients

Radiation therapy uses high-energy radiation beams to treat cancer. About half of people with cancer will receive radiation as part of their treatment. Radiation is used by itself or with chemotherapy. In some cases, radiation may be used to shrink cancer cells before a patient has surgery or to reduce recurrence after surgery.

Our radiation oncology clinic offers the most up-to-date technology available. Equally important, our team is dedicated to your comfort and to clear communication, every step of the way. Please feel free to call us any time – before, during or after your radiation therapy.

Scheduling and treatment

To schedule an appointment with your radiation oncologist, you'll need a referral from your primary care physician or from a medical specialist, such as a urologist, surgeon or medical oncologist.

When you call to schedule your appointment, please be ready to provide the name of your referring physician, your insurance information, your diagnosis and the name of the physician with whom you'd like to meet.

To schedule your appointment, please call Clackamas Radiation Oncology Center: (503) 513-3300.


At your first appointment, you'll discuss your particular treatment options with your radiation oncologist. This is called a consultation. If you're considering radiation therapy, you must first meet with a radiation oncologist to see if radiation therapy is right for you. During your first visit, this doctor will evaluate your need for radiation therapy and the likely results of this treatment. The consultation includes reviewing your:

  • Current diagnosis
  • Personal and family medical history
  • Medications
  • Allergies
  • Lifestyle

The doctor will also perform a physical exam.

If it's decided that radiation therapy should be included in your treatment plan, the next step will be a treatment planning session called a simulation.

Simulation and treatment plan

Radiation therapy must be aimed precisely at the same target or targets each and every time you receive treatment. Your radiation oncologist will ensure this happens by performing a simulation before you start treatment. This is essentially a run-through that allows your radiation oncologist to map out the exact areas to be treated.

First, you will be placed on the simulation table in the exact position you will be in during your daily treatments. Next, a radiation therapist, under your doctor's supervision, will construct an immobilization device (a mold, cast or headrest) that will help you stay in the same position at each treatment. Marks will be placed on your skin or the immobilization device to help in the setup for each treatment.

Your radiation oncologist also may request that special blocks or shields be made for you. These can shape the radiation to conform to your tumor and to keep the rays from hitting normal tissue.

External beam therapy

The most commonly used type of radiation therapy is called external beam therapy. This process directs radiation at your tumor from a machine located away from your body, as with a diagnostic X-ray machine. Because radiation usually is given as a series of outpatient treatments, you may be able to keep up with your normal daily activities during the course of your therapy.

At the beginning of each therapy session, the radiation therapist will help place you in the right position, guided by the marks on your skin or on your immobilization device(s). This typically takes from five to 15 minutes. The therapist will then go to a control area next door to closely monitor you on a television screen while giving you the radiation. He or she may move the treatment machine during your session to target the radiation beam to the exact area of the tumor. You'll be able to talk with the therapist throughout your session. Time spent in the treatment room generally ranges from 10 to 40 minutes.

Your radiation therapy will be precisely mapped to reduce the dose to the normal tissue surrounding the tumor. Still, radiation will affect some healthy cells. Time between daily treatments allows your healthy cells to repair much of the radiation effect, while cancer cells are not as likely to survive the changes. If you develop significant side effects, you may need a break from treatment for a day or more. These missed treatments may be made up with the addition of treatments at the end of therapy.

Treatments are usually scheduled five days a week, Monday through Friday, and they normally continue for one to 10 weeks. The number of radiation treatments you'll need depends on your particular diagnosis, your treatment goals and your general health.


Brachytherapy is a type of radiation therapy that involves placing radioactive sources inside your body, usually in or just next to a tumor. Special catheters or applicators are used to position the sources accurately. Depending on your cancer, the radioactive sources will be placed either temporarily or permanently.

There are two main types of brachytherapy: intracavitary treatment and interstitial treatment. With intracavitary treatment, the radioactive sources are placed in a space next to where the tumor is located, such as the cervix, the vagina or the windpipe. With interstitial treatment, the radioactive sources are inserted directly into the tissues, such as the prostate.

Weekly status check

During radiation therapy, your radiation oncologist and nurse or medical assistant will see you regularly to follow your progress, assess your condition for any side effects, recommend ways to manage these side effects (such as medication), and address any concerns you may have. As treatment progresses, your doctor may make changes in the schedule or treatment plan, depending on your response or reaction to the therapy.

Your radiation therapy team will meet regularly with other health care professionals to review your case and to make sure your treatment is going as planned.

Regular verification of treatment field

During the course of your treatment, your care team will check daily or weekly to make sure your radiation treatment beams are positioned exactly right. To do this, they will take X-ray-type images using the treatment beam itself, or they may do a cone-beam CT (computed tomography) scan, in which the treatment machine moves around you to take a scan. The images, called portal verifications, are an important quality assurance check, but they don't evaluate the tumor itself.


After you complete your radiation treatment, you will have follow-up appointments with your radiation oncologist to make sure you're recovering normally and to check up on your health. Your radiation oncologist may also order additional diagnostic tests. He or she will send reports on your progress to the other doctors helping treat your cancer.

As time goes by, you won't need to see your radiation oncologist as often. However, your radiation oncology team will always be available to talk with you about questions or concerns.

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