Question: My mom was recently diagnosed with lung cancer, and her healthcare team recommended radiation as part of her treatment. We don’t know much about radiation yet. What are the different types of radiation therapy, and how are they given? Is it difficult to deliver radiation to a tumor in the chest since the person will be breathing?

(Answered by Dr. Megan E. Daly from UC Davis Comprehensive Cancer Center during her appearance on the Lung Cancer Living Room. It has been edited slightly for this use.)

Answer: Radiation therapy uses intersecting beams of photons to kill a tumor. We use a machine called the linear accelerator, which is just a big machine that puts out high-energy streams of photons. At the very simplest, that can mean just a single beam coming out. But often, we want to be more precise, so we have several beams coming from different angles that intersect on a tumor to limit any spill-off radiation to any of the surrounding organs like the lungs or the heart.

Types of radiation

There are some acronyms that you may hear from your doctor or see written in your chart to describe these types of radiation.

3D Conformal Radiation Therapy (3D CRT)

This type of radiation is several beams from different angles, all coming together and targeting a tumor based on a CT scan.

Intensity Modulated Radiation Therapy (IMRT)

This type of radiation allows you to sculpt the radiation dose around the structure. For example, if you have a tumor in the middle of the chest, and you want to treat that tumor but not give a lot of radiation to somebody’s esophagus, heart, and airways that are all nearby, you want that radiation to wrap around certain structures and make a complicated shape by having lots of beams coming from different directions.

Saber (SBRT)

This type of radiation is very similar to IMRT, except it gives big doses of radiation over a small number of treatments – usually between one and five. It also requires making sure somebody is immobilized really well so that they’re not moving to make sure you have really good imaging, and you can line the tumor up well.

Respiratory motion and moving tumors

Radiation oncologists do have to take into account respiratory motion and moving tumors, and there are a few ways we can do this.

Four-dimensional CT scan

Most of the time, when we’re going to be treating a moving tumor in the chest, we start with doing something called a four-dimensional CT scan. Instead of doing a normal CT scan, we’re doing a CT scan that’s almost a video of your chest while you’re breathing so we can see how the tumor moves. Sometimes, if the tumor doesn’t move much, we can just treat the entire area. This is the simplest way of dealing with motion.

Breath hold

We can also do what is called a “breath hold,” which is what it sounds like. We have our patients hold their breath, turn the beam on, and then about 15 seconds later, we let them breathe again. We turn the beam on multiple times and only treat the tumor while they’re holding their breath. That’s a pretty effective way and works well.

Abdominal compression

We can also use something called abdominal compression. The goal is getting somebody to breathe less deeply so their tumor doesn’t move up and down quite as much. Putting a belt over somebody’s abdomen works well. They’ll take shallower breaths, and you can usually decrease the amount that the tumor is moving.

Linear acceleration

The fancier way of accounting for movement is the linear accelerator machine that can turn off and on while somebody is breathing, so it can track the tumor and only turn on when it’s in a certain space.

To learn more about radiation and other lung cancer treatments, contact our treatment and trial navigators at 800-298-2436, email support@go2.org, or use the “Lung Cancer Questions?” tab on the right.

Please note that the information included in any published answer is for educational pursuit only and is not intended or implied to be a substitute for professional medical advice. The reader should always consult their healthcare provider to determine the appropriateness of the information for their own situation. Nothing from GO2 for Lung Cancer should be construed as an attempt to offer or render a medical opinion.