Radiation therapy (also called radiotherapy) is a cancer treatment that uses high doses of radiation to kill cancer cells and shrink tumors. At low doses, radiation is used in x-rays to see inside your body, as with x-rays of your teeth or broken bones.


At high doses, radiation therapy kills cancer cells or slows their growth by damaging their DNA. Cancer cells whose DNA is damaged beyond repair stop dividing or die. When the damaged cells die, they are broken down and removed by the body.

Radiation therapy does not kill cancer cells right away. It takes days or weeks of treatment before DNA is damaged enough for cancer cells to die. Then, cancer cells keep dying for weeks or months after radiation therapy ends.


There are two main types of radiation therapy, external beam and internal.

The type of radiation therapy that you may have depends on many factors, including:

  1. The type of cancer
  2. The size of the tumor
  3. The tumor’s location in the body
  4. How close the tumor is to normal tissues that are sensitive to radiation
  5. Your general health and medical history
  6. Whether you will have other types of cancer treatment
  7. Other factors, such as your age and other medical conditions
  8. External Beam Radiation Therapy

“External beam radiation therapy comes from a machine that aims radiation at your cancer. The machine is large and may be noisy. It does not touch you, but can move around you, sending radiation to a part of your body from many directions.

External beam radiation therapy

 is a local treatment, which means it treats a specific part of your body. For example, if you have cancer in your lung, you will have radiation only to your chest, not to your whole body.”

Internal Radiation Therapy

Internal radiation therapy is a treatment in which a source of radiation is put inside your body. The radiation source can be solid or liquid.

Internal radiation therapy with a solid source is called brachytherapy. In this type of treatment, seeds, ribbons, or capsules that contain a radiation source are placed in your body, in or near the tumour. Like external beam radiation therapy, brachytherapy is a local treatment and treats only a specific part of your body.


With brachytherapy, the radiation source in your body will give off radiation for a while.

Internal radiation therapy with a liquid source is called systemic therapy. Systemic means that the treatment travels in the blood to tissues throughout your body, seeking out and killing cancer cells. You receive systemic radiation therapy by swallowing, through a vein via an IV line, or through an injection.

With systemic radiation, your body fluids, such as urine, sweat, and saliva, will give off radiation.


“Radiation therapy is used to treat cancer and ease cancer symptoms.

When used to treat cancer, radiation therapy can cure cancer, prevent it from returning, or stop or slow its growth.

When treatments are used to ease symptoms, they are known as palliative treatments. External beam radiation may shrink tumors to treat pain and other problems caused by the tumor, such as trouble breathing or loss of bowel and bladder control. Pain from cancer that has spread to the bone can be treated with systemic radiation therapy drugs called radiopharmaceuticals.


For some people, radiation may be the only treatment you need. But, most often, you will have radiation therapy with other cancer treatments, such as surgery, chemotherapy, and immunotherapy. Radiation therapy may be given before, during, or after these other treatments to improve the chances that treatment will work. The timing of when radiation therapy is given depends on the type of cancer being treated and whether the goal of radiation therapy is to treat the cancer or ease symptoms.”

When radiation is combined with surgery, it can be given:

Before surgery,

to shrink the size of the cancer so it can be removed by surgery and be less likely to return.

During surgery,

so that it goes straight to the cancer without passing through the skin. Radiation therapy used this way is called intraoperative radiation. With this technique, doctors can more easily protect nearby normal tissues from radiation.

After surgery

to kill any cancer cells that remain.

Lifetime Dose Limits

There is a limit to the amount of radiation an area of your body can safely receive over the course of your lifetime. Depending on how much radiation an area has already been treated with, you may not be able to have radiation therapy to that area a second time. But, if one area of the body has already received the safe lifetime dose of radiation, another area might still be treated if the distance between the two areas is large enough.

Radiation Therapy Can Cause Side Effects

Radiation not only kills or slows the growth of cancer cells, it can also affect nearby healthy cells. Damage to healthy cells can cause side effects.


“Radiation therapy can be expensive. It uses complex machines and involves the services of many health care providers. The exact cost of your radiation therapy depends on the cost of health care where you live, what type of radiation therapy you get, and how many treatments you need.”


“Talk with your health insurance company about what services it will pay for. Most insurance plans pay for radiation therapy. To learn more, talk with the business office at the clinic or hospital where you go for treatment. If you need financial assistance, there are organizations that may be able to help. To find such organizations, go to the National Cancer Institute database, Organizations that Offer Support Services and search for “financial assistance.” Or call toll-free 1-800-4-CANCER (1-800-422-6237) to ask for information on organizations that may help.”

You can expect these steps before beginning treatment:

Meeting with your radiation oncologist.

 The doctor will review your medical records, perform a physical exam, and recommend tests. You will also learn about the potential risks and benefits of radiation therapy. This is your opportunity to ask questions.

Giving permission for radiation therapy.

 If you choose to receive radiation therapy, your health care team will ask you to sign an informed consent form.

Signing the document means:

Your team gave you information about your treatment options.

You choose to have radiation therapy.

You give permission for caregivers to deliver the treatment.

You understand the treatment is not guaranteed to give the intended results.

Simulating and planning treatment.

 The first radiation therapy session is a simulation. This is a practice run without giving radiation therapy. Your team will use imaging scans to identify the tumor location. These may include:

A computed tomography (CT) scan

Magnetic resonance imaging (MRI)

An x-ray

Depending on the area being treated, you may receive a small mark on your skin. This will help your team aim the radiation beam at the tumor.

You may also be fitted for an immobilization device. This could include using:


Foam sponges



Plaster casts


These items help you stay in the same position throughout treatment.

For radiation therapy to the head or neck, you may receive a thermoplastic mask. This is a mesh mask that is molded to your face and secured to the table. It gently holds your head in place.

Your radiation oncology team cares about your comfort. Talk with the team to find a comfortable and reproducible position for treatment. And tell them if you experience anxiety lying still in an immobilization device. Your doctor can prescribe medication to help you relax.


After the simulation, your team will review your information and design a treatment plan. Computer software helps the team develop the plan.

Each session is quick and painless, lasting about 15 minutes. Typically, people have treatment sessions 5 times per week, Monday through Friday. This schedule continues for 3 to 9 weeks.

This type of radiation therapy targets only the tumor. But it will affect some healthy tissue surrounding the tumor. The 2-day pause in treatment each week allows your body to repair this damage.

Internal radiation therapy

Internal radiation therapy is also called brachytherapy. This includes both temporary and permanent placement of radioactive sources in the tumor site.

Typically, you will have repeated treatments across a number of days and weeks. These treatments may require a brief hospital stay.

You may need anesthesia to block the awareness of pain while the radioactive sources are placed in the body.


Most people feel little to no discomfort during treatment. But some may experience weakness or nausea from the anesthesia.

You will need to take precautions to protect others from radiation exposure. The need for such precautions ends when:

  • The permanent implant loses it radioactivity
  • The temporary implant is removed

Weekly reports

During treatment, your radiation oncologist will check how well it is working. Typically, this will happen at least once a week. If needed, he or she may adjust your treatment plan.

Personal care

Many people experience the following during treatment:

  • Fatigue
  • Sensitive skin at the site of radiation exposure
  • Emotional distress
  • Consider these ways to care for yourself:
  • Plan for extra rest.
  • Eat a healthy diet.
  • Seek emotional support.
  • Treat skin with lotions approved by your health care team.
  • Minimize exposure to the sun.
  • Learn more about coping during treatment.
  • After treatment
  • Once treatment ends, you will have follow-up appointments with the radiation oncologist. This involves:
  • Checking on your recovery
  • Watching for treatment side effects, which may not happen right away
  • As your body heals, you will need fewer follow-up visits.
  • Ask your doctor for a written record of your treatment.

Comment (1)

Leave a Reply

Your email address will not be published. Required fields are marked *