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Radiation Therapy for Childhood Cancer

Radiation therapy is a treatment used for many forms of childhood cancer.

This therapy uses beams of radiation, either X-rays or protons, to shrink tumors and kill cancer cells. Radiation works by damaging the DNA inside cancer cells.

The radiation oncologist is the doctor in charge of radiation therapy. The radiation oncologist works with the radiation therapy team to develop a treatment plan for each child’s case.

Sometimes radiation may be the only treatment. Or the treatment plan may combine radiation therapy with other treatments, such as surgery and chemotherapy.

Radiation targets cancer but may damage nearby healthy tissue. This damage can cause side effects. Some side effects can affect the growth and development of children and adolescents. The medical team designs treatments to protect as much healthy tissue as possible.

Receiving Radiation Therapy


The patient and family will meet members of the treatment team. The team will explain the treatment process and answer questions. Families should write down questions before this appointment and should feel comfortable asking the treatment team if something is not clear. Sometimes it’s helpful to bring a family member or friend along to help take notes. If families think of more questions after the appointment is over, they should contact the team for answers.

The doctor may talk to parents about whether patients should receive sedation. Doctors may recommend sedation for young children and other patients who have trouble staying still.

The treatment team will talk to parents about the goal of radiation treatment and side effects. This process is called informed consent. It is where a patient and the family gives permission before treatment can start.

Radiation therapist prepares the computer for a pediatric cancer radiation treatment with another radiation therapist and a patient in the background.

Much preparation and planning goes into designing treatments that will most effectively destroy cancer, limit damage to healthy cells, and lessen late effects.


Simulation is the first step in planning the patient’s radiation treatment. The patient will have a CT scan and sometimes an MRI to show exactly where the tumor is (or was if surgery was performed).

Before the simulation, patients will have a customized mask or body mold made that will help them lie in the proper position for treatment.

Contrast for CT or MRI

In most cases, patients will receive a contrast agent for either CT or MRI simulation. The patient’s schedule will contain directions about not eating or drinking before receiving the contrast. It is very important to follow the guidelines exactly. Notify the therapy team of any history of allergies to contrast.

If contrast is used the patient will need an IV. If the patient does not have a port, central line, or other IV device, a nurse will need to start an IV.

The CT scan is an X-ray study that is needed to help calculate the radiation treatment plan. The patient lies in their mask or body mold on a flat table (called a couch) and the table automatically slides (or moves) through the scanner that looks like a large ring or donut. This process is how the images are made. It takes about an hour.

When an MRI is used to help with radiation treatment planning the patient lies in their mask or body mold and the area to be imaged is placed inside the magnet (inside the round opening in the MRI device). The MRI device makes loud noises, so either ear plugs or headphones are used to protect the ears. The MRI usually takes 30 minutes to an hour.

The patient should wear loose, comfortable clothing that does not contain metal such as snaps, buttons, and zippers. The best clothing choices may include T-shirts with sweat pants, pajama bottoms, or other elastic waist pants. The treatment team will often have the patient wear a hospital gown.

During the simulation several steps will be followed to make sure the radiation is delivered in the precise treatment location each time.

Measuring/ marking

  • A radiation therapist or nurse may place a small tattoo (freckle size) on the patient’s skin using a very small, sterilized needle. Only the tip of the needle is used. Some pediatric centers may use a permanent marker or paint pen instead. 
  • This mark helps radiation to be directed safely and precisely to the treatment area.
The radiation oncologist will work with dosimetrists and physicists to plan the amount and frequency of radiation and map the radiation beams.

The radiation oncologist will work with dosimetrists and physicists to plan the amount and frequency of radiation and map the radiation beams.

Treatment Planning

After the simulation, the radiation oncologist will work with dosimetrists and physicists to develop a treatment plan.

The team will plan the amount and frequency of radiation and map the radiation beams.

The radiation oncologist will write a prescription that outlines exactly how much radiation is to be given, how often, and where. Not all cancers are treated with the same amount of radiation. The treatment plan depends on many factors, including the type of tumor and the age of the child.

Before the first treatment begins, the radiation therapy team will take X-ray images on the treatment machine of the patient and check that all of the treatment machine settings are correct. These images confirm the area being treated is the precise location the doctor planned. The doctor will approve the images before the first radiation treatment begins.

Working with the patient family

The radiation oncologist will explain the patient’s treatment plan to the family before treatment sessions begin. This is an excellent time for families to ask questions. A child life therapist may work with the patients to explain the treatment process using child-friendly language and medical play.

The radiation oncologist will explain:

  • About how long each radiation treatment session will take.
  • The total number of treatments (a common schedule is 5 days a week for anywhere from 1 to 7 weeks.)
  • How many “rest” days there will be between the patient’s treatments. This time off gives the radiation time to kill cancer cells and helps healthy cells recover. Typically the patient won’t have treatments on weekends.
  • The radiation oncologist will also talk to patients and families about the importance of the patient remaining still during treatment sessions. Child life specialists can work with patients on relaxation techniques.
  • If patients aren’t able to stay still, sedation may be used, so an anesthesiologist may also be part of the patient’s treatment team.
Radiation therapist positioning a patient on a body mold, also called a bean bag, with another radiation therapist in the background.

Radiation therapy patients will be fitted for a device to ensure they stay in the same position during each treatment. These devices may be a mask or body mold, also called a bean bag.

A typical radiation therapy appointment

Most patients receive radiation treatment as an outpatient. The scheduler will work with families to make radiation appointments. If the patient is receiving sedation, there will be a separate appointment for this procedure.

Patients and families should always follow the registration procedure of their pediatric center.

Typically the schedule will be similar to the following:

  • Before each visit, patients and parents check in at the registration desk. Then they go to the radiation oncology waiting area. Pediatric waiting rooms will usually have a play area.
  • When it is time for treatment, someone from the care team, usually the radiation therapist or radiation oncology nurse, will escort the patient and perhaps a parent to the treatment area.
  • If sedation is required, a member of the anesthesia team will meet the patient and parent. At some treatment centers, a parent can stay with the patient until it is time for the radiation treatment to begin. Some centers will ask parents to remain in the waiting area.
  • In the treatment room, the radiation therapist or nurse will position the patient on the radiation table using the patient’s mask or body mold. The team will make the patient as comfortable as possible, perhaps with a blanket or a special cushion placed under the patient’s legs. (Sometimes positioning takes longer than the actual radiation session.)
  • The radiation therapist will go to an adjoining or nearby room to begin the radiation treatment. The patient will be alone in the radiation treatment room. But the therapist can see, hear, and talk to the patient at all times.
  • The machine will align to target the radiation to the precise treatment location sometimes by taking an X-ray image of the patient. The patient will see laser beams used for positioning the radiation but will not feel them.
  • The patient cannot feel or see the radiation treatment as it is delivered, but the machine will make noise.
  • After the treatment session, the care team will help the patient off the bed. If sedation was not used, patients can usually return to normal activities. If a sedative was given, the patient must recover from its effects before leaving the radiation oncology area.

Follow-up visits

The patient will have regular follow-up visits with the radiation oncologist. During follow-up visits, patients will have diagnostic imaging tests, usually CT, PET or MRI scans to monitor how well the cancer is responding to treatment.

Helpful Tips

  • Arrive on time for radiation therapy appointments, even a few minutes early to allow time for check-in. When patients are late, it can complicate the radiation oncology schedule for other patients. Patients who are late may have to wait until other patients receive their treatment.
  • If a mask is used during radiation treatment, the patient’s hairstyle needs to be the same as it was when the mask was made. This may mean getting a haircut before simulation if it is expected that the patient may lose their hair.
  • It is best to wear loose, comfortable clothing such as T-shirts with sweat pants, pajama bottoms, or other elastic waist pants.
  • Pediatric centers have different policies concerning parents observing therapy sessions. Some will allow one or both parents to observe. Others will ask parents to remain in the waiting area. Siblings will most likely not be allowed to observe sessions and will have to stay in the waiting area under the supervision of an adult. Families should plan accordingly, so an adult is there to watch siblings at all times.
Two radiation therapists preparing a pediatric cancer patient for a radiation treatment.

Radiation therapy usually treats a small, localized area of the body such as a portion of the brain, spine, soft tissue, or bone. 

Reviewed: June 2018