Radiation therapy uses strong X-rays or other types of radiation to kill cancer cells or stop them from growing. There are different types of radiation therapy. For non-Hodgkin lymphoma, radiation is most often directed at the cancer from a machine outside of your body. This is called external radiation therapy.

Your doctor may advise external radiation in these cases:

• As the main treatment if you have a type of lymphoma that is only in one place in your body

• As the main treatment if you have a type of lymphoma that is in a few places that are close to each other

• As part of the treatment for other types of non-Hodgkin lymphoma, especially if you have a large or bulky tumor

• To help relieve symptoms such as pain, by shrinking lymphoma tumors

• As part of your treatment if you are getting a stem cell transplant. In this case, radiation is given to most of your body over a short period of time. This is known as total body irradiation.

Some people with lymphoma only in the skin might have electron beam radiation therapy. This treatment only affects your skin. It doesn’t go deeper into your body. This helps limit the side effects.

For this treatment, a doctor called a radiation oncologist creates your treatment plan. The plan shows what kind of radiation you’ll have and how long the treatment will last. This doctor can also prepare you for how you may feel during and after the treatment.

Radiation treatment is often done as an outpatient in a hospital or a clinic. That means you don't need to stay overnight in the hospital.

To prepare for your treatment, you will have a session called a simulation. This session helps decide which position you'll need to be in for your radiation treatments. Your doctor will want to make sure that the radiation is directed at the exact same spot each time. The appointment may take up to 2 hours. Here's what you can expect during this process:

• You may have imaging scans, such as CT scans. These scans let your doctor see inside your body. They help show the exact location of the lymphoma. Your doctor then knows exactly where to aim the radiation.

• You'll lie still on a table. A radiation therapist will use a machine to define your treatment field. That field is the exact spot on your body where the radiation will be aimed. You may have more than one treatment field if you have lymphoma in more than one place. You will get into a comfortable position. Then the radiation therapist will mark the area of your body where the radiation will go. This will be marked with an ink dot, or a tattoo. This won't wash off right away in the shower.

• If you're having total body irradiation, you may have to stand in a special machine. Or you may lie down on your stomach or your back.

• You may have special protective shields put over organs such as your lungs, heart, and kidneys. This helps to protect them from the radiation.

• You may also have body molds made. These are to help keep you comfortably in place during the treatment.

The treatment is a lot like getting an X-ray. You stay in the radiation room for about 20 to 30 minutes. The radiation will probably take just a few minutes.

You’ll lie on a table while the machine is placed over you. The radiation therapist will line up the machine exactly with your marked treatment fields. The radiation therapist will leave the room to turn on the machine. You will be able to talk to each other over an intercom. You may hear whirring or clicking noises.

You may have radiation treatments every day for 5 days in a row for several weeks. You will not be radioactive during this time.

Radiation therapy affects normal cells as well as cancer cells. This can lead to side effects. The side effects of radiation depend on the part of your body being treated and other factors. You may feel better during your radiation treatment if you get plenty of rest and eat well. Most side effects get better over time once treatment is over.

Common side effects include:

• Skin in the treated area that’s dry, irritated, and sensitive

• Short-term hair loss in the area being treated

• Tiredness

• Feeling weak

• Worsening of chemotherapy side effects

Radiation to your chest or neck can cause:

• Dry mouth, caused by damage to your salivary glands

• Painful swallowing or burning in your throat, caused by irritation of the esophagus. This is called esophagitis.

Radiation of your stomach can cause:

• Nausea and vomiting

• Loose stool, or diarrhea

Total body radiation can cause:

• Short-term side effects that are more severe

• An increased risk for infection, from low white blood cell counts and from damaged skin and mucous membranes

Call your healthcare provider if you have signs of infection, such as fever or pain. Ask what other symptoms you should call your healthcare provider about.

Radiation can also sometimes cause damage that may not show up until months or years after treatment. Depending on where the radiation was aimed, this can include:

• Lung or heart damage, from radiation to your chest

• Damage to the thyroid gland, from radiation that reaches your neck

• Headaches or memory loss, from radiation to your head

• An increased risk for another cancer in the area that was treated