Linear Accelerator

Additional Information

More than half of U.S. cancer patients receive radiation therapy ― and many of these treatments wouldn’t be possible without a machine called a linear accelerator (LINAC). Mercy uses many of the latest-generation LINACs to provide highly targeted and effective cancer treatment.

What Is a Linear Accelerator?

A linear accelerator, also referred to as LINAC, is a machine that aims radiation at cancer tumors with pinpoint accuracy, sparing nearby healthy tissue. It’s used to deliver several types of external beam radiation therapy, including:

LINACs help Mercy cancer specialists treat cancers of the brain, spine, head and neck, lung, breast, esophagus, stomach, rectum, uterus, prostate, bladder, liver and bones.

How Does a Linear Accelerator Work?

LINACs send radiation, such as x-rays or electron beams, through the body and into cancer tumors. Today’s LINACs are equipped with 3D image guidance like CT scanning to accurately target tumors. Special software then matches radiation beams to unique tumor sizes and shapes. This customized approach makes external beam radiation therapy safe and precise for cancer treatment.

What to Expect From Radiation Therapy Using a LINAC


Your treatment plan is tailored to your cancer type and unique needs. Your Mercy cancer care team explains your plan and provides a treatment schedule.


You’ll undergo a simulation, which is a CT scan performed in the treatment position. Some simulations also include an MRI or PET scan. You may need tiny markers (or fiducials) placed in your body or small tattoos inked on your skin. This helps your care team quickly locate your tumor and ensures your body is correctly positioned for treatment. You may also need to use a positioning device to help you remain still during treatment, such as a body mold, face mask or head frame.

Your radiation therapist will go into a control room to start treatment but will continue monitoring you. You can still communicate with the team if needed, so let them know if you feel uncomfortable.


After treatment, your Mercy cancer specialist may order imaging, bloodwork or other tests to check your progress and modify treatment if needed.

Side Effects from Radiation Therapy Using a LINAC

Temporary side effects may include fatigue or skin changes like redness, itching or peeling. Depending on the area of the body treated, other side effects may include headache, trouble swallowing, digestion problems or bladder changes.

Side effects usually go away a few months after treatment, but it’s possible they’ll become severe or won’t improve. Late side effects can appear months or years after treatment and vary by the area treated and radiation dose. Talk with your care team about potential side effects and ways to manage them.

Questions or concerns about external beam radiation or the LINAC machine? Talk with your Mercy cancer care team. We’re here with the expertise, advanced technologies and compassionate care you need to fight cancer.

Coordinated Radiation Oncology Care

At Mercy, your oncologist plans, prescribes and supervises your care. They’re supported by a team that includes physician assistants, registered radiation therapists, nurses, medical physicists, dosimetrists and other support personnel. Our team approach helps us provide you with complete care and services on your cancer journey.

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