Careful Preparation Goes Into Planning Radiation Therapy
- A radiation simulation maps out the treatment area using an imaging scan
- The skin is marked with ink to guide the radiation oncologist to the right spot
- You may learn how to hold your breath to protect your heart and lungs from radiation
“Your radiation oncologist needs about a week to design the radiation plan,” Dr. Chelsea Pinnix, radiation oncologist at MD Anderson Cancer Center, tells SurvivorNet. “Sometimes it can be more than that before your radiation treatment actually begins.”
Read MoreRadiation Simulation
Before you have your first radiation treatment, you’ll go through a simulation to help your radiation oncologist plan out your treatment. During the simulation, the technician will map out the area that will get radiation, create a mask to keep your head in place, and teach you how to hold your breath. To start, you’ll have a computed tomography (CT) scan — an imaging test that uses x-rays to take detailed pictures from inside your body. The scan will outline your tumor to make it easier to see against the surrounding healthy tissues.The therapist will create a device to hold you in the proper position each time you’re treated. This is to ensure that radiation is delivered to the same spot each time. If you’re getting radiation close to your head, you may have a customized mask created from a mold of your head.
The therapist will mark your skin over the tumor with small dots of ink, so that your radiation oncologist can easily find the right spot during each treatment. These dots may be permanent tattoos, to ensure that they stay in place throughout the entire course of your radiation treatment. The technician might also create a special mold that goes behind your head and neck to hold your body still during treatment.
The whole planning session will last between 30 and 90 minutes. You’ll need to keep still throughout the scan, but your therapist will do everything possible to keep you comfortable the entire time.
Learning How to Hold Your Breath
During the planning session, you may also learn a technique called deep inspiration breath hold (DBH), if you’re going to be getting radiation to your chest. In DBH, you take a deep breath and hold it for up to 20 seconds while the radiation is delivered.
Holding your breath has several purposes. For one thing, it reduces radiation exposure to both your lungs and heart. When you take a deep breath and your lungs fill with air, your diaphragm pulls your heart away from your chest. This reduces the amount of radiation delivered to your heart. By increasing the volume of your lungs, you’ll also reduce the amount of radiation exposure to them, Dr. Pinnix says.
Breath-holding has another important purpose: it helps you keep still so your radiation oncologist can deliver the treatment more precisely. Whenever you breathe, your chest expands and contracts. “It takes the motion out of the picture so that we can make our fields that much smaller,” Dr. Pinnix adds.
A Phantom Patient
A number of steps go into planning your radiation. Once the process is finished, most centers will verify that the plan is accurate by testing it out on a “phantom” patient. They’ll place a mannequin into the radiation machine, often at night when the machine isn’t being used, and then administer your radiation plan to it.
Your radiation oncologist will check the doses on that mannequin to make sure that the plan they’ve approved will really work on you, Dr. Pinnix says.
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