Radiation therapy is the use of X-rays to treat tumors.
Doctors first figure out the precise location of the tumor using computed tomography (CT) and magnetic resonance imaging (MRI) scans. Then they use special machines to aim X-ray beams at that site from several angles.
The beams can travel through outer structures, such as skin and bones, to reach the depth of the tumor and kill the tumor cells there.
The technology for this type of treatment has changed remarkably in recent years, even in just the past five years.
Now, doctors are able to target tumors better and to spare healthy areas or limit damage to them. This means fewer side effects for children in the short term and the long term.
Some children with neuroblastoma may be able to have a newer type of radiation therapy called I-131-MIBG therapy. This is a way to get radiation inside your child’s body and into their cancer cells via the bloodstream.
Types of Treatment
Some types of radiation machines may emit beams wider than the place where your child needs treatment. So doctors use blocks inside the machine to stop segments of the beam that would otherwise hit healthy tissue.
Other types of machines emit more focused beams and may be right for certain types of tumors or tumor sites.
We offer four main types of radiation therapy:
Three-dimensional conformal radiotherapy
This was the standard for many years and is still useful in many situations. It focuses two or three X-ray beams on the tumor site.
This is becoming more common. It allows doctors to use more beams and to focus them in a more precise way to confine the radiation to the tumor.
Fractionated stereotactic radiotherapy
This can be focused even more precisely and is good for certain types of tumors, such as craniopharyngiomas, pituitary adenomas, retinoblastomas and other small brain tumors. It helps spare normal brain tissues.
Gamma knife therapy
Also called radiosurgery and stereotactic radiosurgery, this type delivers a single high-dose beam very precisely. It is used for some brain tumors and problems with blood vessels to the brain.
If your child needs radiation therapy, her health care team will talk with you about which type is the best choice and why, and how long the treatment will last.
Most children who get radiation come for treatment each day Monday through Friday for several weeks. The treatment itself takes about 30 to 40 minutes per session.
Where Treatment Happens
Our young patients get their radiation treatment in the Cancer Center at University of Washington Medical Center, which has a pediatric radiation therapy service. Gamma knife therapy is performed at Harborview Medical Center.
To keep the beams aimed at the right spot, children must be very still during treatment. Most children younger than 5 years of age get anesthesia before each radiation treatment.
For children who need this, a pediatric anesthesiologist from Seattle Children’s goes to the UW Medical Center or Harborview.
Finding Out What Your Child Needs
Each week our doctors from various specialties, such as medicine, surgery and radiation, meet at our General Tumor Board and our Brain Tumor Board.
These meetings provide a time when our team can talk as a group about each patient and develop treatment plans. Your child's doctors will discuss whether radiation is a good treatment choice for your child. Then they will let you know what they suggest.
Dr. Ralph Ermoian, a radiation oncologist, attends both boards to help the teams assess whether radiation may be helpful.
Here are the steps you can expect if your child needs radiation:
- If we think your child needs radiation therapy, we will ask you to come see us to talk about the reasons, the benefits and the possible side effects.
- If you agree that radiation is a good treatment for your child, we will have a second meeting for detailed treatment planning. We will do a CT scan of the tumor site to tell right where the tumor is, and we will figure out just how we want to carry out the sessions. This is called a simulation.
- Next, we will take one to two weeks for technical work to figure out the best angles for treatment and to set up the equipment.
- If your child needs anesthesia before treatment, the next step is to have her come in for the first radiation treatment. First, we will give your child anesthesia. Then we will do a “dry run” with your child to make sure everything is set properly. Once we confirm all settings are correct, and while she is under anesthesia, we will give your child the first dose of radiation.
- If your child does not need anesthesia, we will still do the “dry run.” Then we will have your child come back for the first treatment a day or two later.
What's Special About the Radiation Therapy Service at Children’s?
Children’s provides multidisciplinary care. We bring together teams of experts from many fields to decide the best treatment plan for each child. This includes our use of radiation.
Dr. Ermoian is the only radiation oncologist dedicated to pediatric care in Washington, Alaska, Montana and Idaho. He has a unique depth of knowledge about cancer care and about the experiences of children with cancer and their families.
He is one of many team members who work to make sure our radiation therapy service focuses on the special needs of children.
We also have a full-time nurse dedicated to caring for our patients who come for radiation therapy. We have a pediatric recovery room, too, which is also staffed by a nurse.
Who Needs Radiation Therapy?
About 50% to 60% of our young cancer patients get radiation. Most get it along with surgery and chemotherapy. Our service is an active one. About 130 of our patients had radiation therapy in 2005.
Some types of tumors respond well to radiation, and others do not. So it is not the right choice for all our young patients.
We use radiation most often to treat brain tumors and sarcomas and we use it to prepare patients for a hematopoietic cell transplant.
We also use radiation for children with Wilms tumors, a type of kidney tumor; neuroblastoma; some cases of leukemia; and some other forms of cancer.