What is radiation therapy?

Radiation therapy uses high-energy beams and particles to kill cancer cells and reduce the size of tumors. Many tumors are more sensitive to radiation compared to healthy tissue.

  • Children often receive a type of radiation called photons. A machine outside the body delivers strong beams of X-rays into the body.
  • Proton therapy is like regular X-ray radiation, except that the beams stop once they reach their target.
  • Sometimes doctors put a small device inside a child’s body that gives off radiation close to the tumor. The device is temporary. This is used for some types of cancer of the bones and muscles.
  • A way to get radiation into cancer cells via the bloodstream is called I-131-MIBG therapy. It is an option for some children with neuroblastoma.

What’s special about radiation therapy at Seattle Children's?

We bring together a team of experts from many fields. We work with you to decide the best treatment plan for your child, including use of radiation.

    • Dr. Ralph Ermoian is the only radiation oncologist dedicated to pediatric care in our region (Washington, Wyoming, Alaska, Montana and Idaho). Radiation can harm healthy cells and damage a child’s developing nervous system. A radiation oncologist who is experienced working with children knows best whether — and how — to use radiation therapy for your child.
    • If your child needs it, a pediatric anesthesiologist who is specially trained in children’s sedation will give them medicine to relax. That way, your child stays still during radiation treatment.
    • Our patients have access to proton therapy through our partnership in the Seattle Cancer Care Alliance (SCCA). SCCA Proton Therapy is the only center to offer this type of radiation treatment in the Northwest.
    • Radiation therapists who have years of training and experience will deliver your child’s treatment, under the guidance of the radiation oncologist.
    • Physicists specializing in radiation treatment will make sure the radiation plan is checked and rechecked and that therapy is delivered as intended.

    • Each week our doctors from radiation oncology and other specialties, such as chemotherapy, surgery, pathology and radiology, meet at our General Tumor Board, our Brain Tumor Board and our Bone Tumor Clinic. Other experts such as neurologists, social workers, eye surgeons and child life specialists may also join the meetings.
    • Dr. Ermoian helps the teams decide if radiation may be helpful and what type of radiation to use.
    • We talk about each child’s case in great detail. By combining our different skills, we can offer your child the safest and most effective treatment plan. This team approach is called multidisciplinary care.
    • Experts at our Cancer and Blood Disorders Center take care of your whole child. We don’t just treat their cancer. We care for your child’s medical, physical, nutritional, hormonal, learning, emotional and comfort needs.

    • We treat more than 100 children using radiation every year. This means everyone on the team has the experience to make a real difference for your child.
    • Our patients range in age from young children to young adults. We work hard to reduce any long-term impact to your child from cancer or its treatment.
    • We know teens and young adults with cancer have different challenges than children and older adults. Our Adolescent and Young Adult Cancer Program (AYA) focuses on their needs.
    • We work with teens and young adults to help preserve their fertility if treatment might harm their ability to become parents.

Types of Radiation Therapy

Radiation technology has changed a great deal in recent years. Now, doctors can target tumors better and avoid healthy areas or limit damage to them. This means fewer side effects for your child, both now and in the future.

We offer these types of radiation therapy:

  • This method focuses a few X-ray beams on the tumor site. It was the standard for many years and is still useful in many situations.

  • With intensity-modulated radiotherapy (IMRT), doctors use more X-ray beams and focus them in a more precise way. That helps confine the radiation to the tumor.

  • This type of radiation is used for tumors that are not as sensitive to normal (X-ray) radiation. These include some types of tumors affecting the salivary glands or bones. This form of radiation may also be used to treat symptoms of disease.

    Our partner, UW Medicine, is the only medical center in North America with a fast neutron treatment system.

  • This type of radiation therapy focuses the X-rays precisely to treat very small areas. This helps avoid harm to normal tissue. Despite the “knife” in the name, there is no cutting. It is good for certain types of tumors in the head and to treat some problems with the blood vessels.

  • This treatment is like gamma knife, but is used for tumors in locations outside the head.

    It is particularly useful for treating some tumors in the lung or spine.

  • Seattle Children’s and SCCA are world leaders in stem cell transplants to treat young people with certain cancers. For some patients, X-ray radiation to the whole body is the best way to prepare their body for the new cells.

  • Unlike X-rays, proton beams stop once they reach their target.

    With protons, the tumor gets the intended high dose of radiation. The healthy tissue beyond the tumor receives even less radiation than with targeted X-ray beams.

    Seattle Children’s offers proton therapy at SCCA Proton Therapy. It is the only proton therapy center in the Northwest. Read more.

  • Seattle Children’s doctors are using a new way to get radiation inside your child's body and into cancer cells via the bloodstream. This type of radiation is called I-131-MIBG therapy.

    Radioactive iodine is attached to a chemical called MIBG that targets neuroblastoma cells. Your child receives this infusion through a vein. We are the only hospital in the Pacific Northwest and 1 of only about 12 centers in the country offering I-131-MIBG therapy for children.

  • To treat some tumors of the bone and connective tissue (such as muscles), doctors place a small device inside your child’s body near the tumor.

    The device gives off radiation. After a short treatment period, doctors remove it.

Who needs radiation therapy?

About 50% to 60% of the children and teens we treat for cancer get radiation. Usually their treatment also includes surgery and chemotherapy.

Some types of tumors respond well to radiation. Others do not. So it is not the right choice for everyone.

We use radiation to treat:

Radiation also may be used to prepare children for a stem cell transplant.

What to Expect

If we think your child needs radiation therapy, we will talk with you about the reasons, the benefits and the possible side effects. If you agree that radiation is a good option for your child, we will plan and prepare the best treatment.

    • Your child will have a CT (computed tomography) scan of the tumor site. This tells us the exact location of the tumor.
    • Depending on how complex treatment will be, it takes several hours to a couple of weeks to figure out the best angles for treatment and to set up the equipment.
    • To make sure everything is set correctly before treatment, your child comes to the treatment room for a “dry run” but does not get any radiation therapy in that first session.
    • If your child needs medicine (sedation) to make them relax so they stay still during radiation treatment, the “dry run” and first treatment happen on the same day. Most children younger than age 7 need sedation.
    • A pediatric anesthesiologist gives your child the medicine. Once we confirm all settings are correct, and while your child is under sedation, we will give the first dose of radiation.
    • The treatment will take place in a large room where the patient is alone but watched continuously with cameras. The team treating your child can talk to your child and your child can talk to them
    • Usually, your child can listen to music or stories during treatment.

  • For external radiation with X-rays or proton beams:

    • Most children come for treatment each day, Monday through Friday, for several weeks.
    • Total time at the center is usually 30 to 60 minutes for each treatment.
    • If your child needs anesthesia, it will take extra time to help them go to sleep and wake up.
    • Most of the time is spent preparing for the treatment and making sure everything is just right.
    • The treatment itself takes about 5 to 10 minutes per session.

    See details on the schedule for I-131-MIBG therapy for neuroblastoma. If your child needs other internal radiation treatment, your doctor will talk with you about timing.

  • Side effects depend on the type of radiation, part of the body and how long treatment lasts. Some children have:

    • Tiredness
    • Sensitive skin or other skin changes
    • Sore mouth or throat
    • Nausea, vomiting or diarrhea
    • Low levels of some types of blood cells

    Your team can help your child manage side effects. Most go away after treatment is finished.

    Sometimes radiation causes long-term problems. It can:

    • Affect the way a child develops
    • Cause infertility
    • Cause tumors later in life

    Our doctors and scientists are working to prevent those problems. They are looking for ways to:

    • Give radiation in smaller doses
    • Expose smaller areas to radiation
    • Get radiation inside the body in new ways

    We work with teens and young adults to help preserve their fertility if treatment might harm their ability to become parents.

    If your child gets an implanted device or I-131-MIBG therapy, their body fluids (like pee and sweat) will give off radiation for several days. We take special steps to make sure your child gets the care they need while containing the radiation. To learn more, see:

Contact Us

Contact the Cancer and Blood Disorders Center at 206-987-2106 for an appointment, a second opinion or more information.

To make an appointment, you can call us directly or get a referral from your child’s primary care provider. We encourage you to coordinate with your pediatrician or family doctor when coming to Seattle Children’s.

Providers, see how to refer a patient (PDF) .