Overview of Radiation Therapy | Purpose | Oncology

Radiation Therapy

What is radiation therapy?

Radiation therapy is a type of cancer treatment that uses beams of penetrating energy to kill cancer cells. It usually uses X-rays, but protons or other types of energy can also be used. The term “radiation therapy” most often mentions external beam radiation therapy. During this type of radiation, the high-energy rays come from a machine outside your body that directs the rays to a precise point on your body. Throughout a different type of radiation treatment called brachytherapy (brak-e-THER-uh-pee), radiation is placed inside your body.

Radiation therapy compensations cells by destroying the genetic material that controls how cells grow and divide. Although radiation therapy damages both healthy and cancer cells, the goal of radiation therapy is to destroy as few normal, healthy cells as possible. Normal cells can often overhaul much of the damage caused by radiation.

Purpose of radiation therapy

More than half of all persons with cancer receive radiation therapy as part of their cancer treatment. Doctors use radiation therapy to treat almost all types of cancer. Radiation therapy is also helpful in treating some non-cancerous (benign) tumors.

How radiation therapy is cast-off in people with cancer

Your doctor may propose radiation therapy as an option at different times during your cancer treatment and for different reasons, including:

  • As the only (primary) treatment for cancer
  • Before surgery, to shrink a tumorous tumor (neoadjuvant therapy)
  • After surgery, to rest the growth of any remaining cancer cells (adjuvant therapy)
  • In combination with other treatments, such as chemotherapy, to kill cancer cells.
  • In advanced cancer to relieve symptoms caused by cancer

Types of radiation therapy

There are two main types of radiation therapy, exterior, and internal beam. The type of radiation therapy you can receive depends on many factors, including:

  • The type of cancer
  • The size of the tumor
  • The position of the tumor in the body
  • How nearby the tumor is to normal tissues that are sensitive to radiation
  • Your medical and general health history
  • If you will have other types of cancer treatment
  • Other influences, such as your age and other medical conditions

External beam radiation therapy

External beam radiation therapy comes from a machine that directs radiation at your cancer. The machine is large and can be noisy. You don’t touch it, but it can move around you, sending radiation to a part of your body from many directions.

External beam radiation therapy is a native treatment, which means it treats a specific part of your body. For example, if you have lung cancer, you will receive radiation only to the chest, not to the whole body.

Internal radiation therapy

Internal radiation therapy is a treatment in which a source of radiation is placed inside your body. The source of radiation can be solid or liquid. Internal radiation therapy with a hard source is called brachytherapy. In this type of treatment, seeds, tapes, or capsules containing a radiation source are placed in your body, in or near the tumor. Like external beam radiation therapy, brachytherapy is a local treatment and luxuries only a specific part of your body.

With brachytherapy, the radiation source in your body will emit radiation for a time.

What to expect?

Your doctor will discuss and other options and help weigh the pros and cons. Before treatment begins, they will determine the correct type and dose of radiation.

A person receiving external beam radiation may have a CT scan or MRI before treatment. This is to identify the exact location and size of the tumor. A doctor can make a small but permanent mark on the skin to make sure the radiation therapist is aiming the beam correctly.

A person may need to wear a cast or use a headrest or other device to ensure that they remain still during treatment. The first session can be a simulation, in which the team performs the procedure.

Many people have five meetings per week for 3-9 weeks, but this depends on specific factors. Each session lasts about 15 minutes. It is painless, but the surrounding tissue will be damaged. That is why the treatment occurs only 5 days a week. The 2-day break allows for healing.

A person receiving internal radiation therapy may need an anesthetic before the doctor can implant the radioactive substance. In general, several sessions and sometimes in the hospital may be necessary. The details of the process depend on the type of radiation therapy and the type and location of cancer.


After receiving external treatment, a person can go home and continue with their daily routine. However, they may experience:

  • Fatigue
  • Tenderness around the treatment site
  • Emotional stress

To help manage these effects, it is important to:

  • Rest a lot
  • Eat Healthily
  • Talking to friends and family about any side effects

Follow the instructions, which may involve skincare, of the treatment team. Avoid spending time in the sun, due to the risk of photosensitivity. Also, monitor for adverse effects and inform your doctor if they occur. Your doctor may recommend additional treatments aimed at alleviating them. People may need to talk to their employers about adjusting work hours or taking medical leave.

Side effects of radiation therapy

Radiation can affect both healthy cells and cancer cells. When this happens, a person experiences side effects. Specific side effects depend on factors such as:

  • The area receiving treatment
  • The general health of the person
  • The type and dose of radiation

Short term side effects

Short-term side effects vary, depending on the part of the body that receives the radiation. They may include:

  • Fatigue
  • Hair loss
  • Diarrhea
  • Skin changes
  • Nausea and vomiting

A 2018 study published in the BMJ open recommends screening for anxiety and depression in people undergoing radiation therapy and offering counseling services to those who may benefit from them.

Long-term side effects

Long-term side effects also depend on the treatment site. They include:

  • Heart or lung problems, if radiation affects the chest
  • Thyroid problems, which cause hormonal changes, if radiation affects the neck area
  • Lymphedema, which involves the accumulation of lymphatic fluid and causes pain
  • Hormonal changes, including the possibility of early menopause, due to radiation to the pelvic area
  • There is a small chance that high doses of radiation in certain areas may increase the risk of another form of cancer developing. A doctor will provide more specific information and help you weigh the risks and benefits.

Not all people who receive radiation therapy experience long-term side effects. The risk depends on the doses, the treatment area, and other individual factors.

What happens after radiation therapy treatment ends?

After treatment is finished, you will have follow-up appointments with your radiation oncologist. It is important to continue your follow-up care, including:

  • Checking your recovery
  • Be on the lookout for treatment side effects, which may not happen right away

As your body recovers, you will need fewer follow-up visits. Ask your doctor for a written record of your treatment. This is a helpful resource for managing your long-term health care.

What happens before radiation treatment?

Each treatment plan is created to meet the individual needs of a patient, but there are some general steps. You can wait for these steps before starting treatment:

Meeting with your radiation oncologist. The physician will review your medical records, perform a physical exam, and mention tests. You will also learn about the possible risks and benefits of radiation therapy. This is a good time to ask questions or share concerns you may have.

Permit radiation therapy. If you choose to have radiation therapy, your healthcare team will ask you to sign an “informed consent” form. Signing the document means:

  • Your team provided you with information about your treatment options
  • Choose to receive radiation therapy
  • You permit healthcare professionals to administer the treatment
  • You understand that treatment is not guaranteed to work as expected

Simulation and treatment planning. Your first radiation therapy session is a simulation. This means that it is a practice without administering radiation therapy. Your team will use imaging scans to identify the location of the tumor. These may include:

  • A computed tomography (CT) scan
  • Magnetic resonance imaging (MRI)
  • An X-ray

Provisional on the area being treated, you may receive a small mark on your skin. This will help your team direct the radiation beam at the tumor. You may also have an immobilization device. This could include the use of:

  • Headband
  • Foam sponges
  • Headrest
  • Molds
  • Plasters

These items help you stay in the same position throughout the treatment. For radiation therapy to the skull or neck, you may obtain a thermoplastic mask. This is a mesh mask that is molded to your face and attached to the table. Gently holds your head in place.

Your body must be in the same position for each treatment. Your radiation oncology team cares about your comfort. Talk with the team to find a comfortable position you can be in each time you come in for radiation therapy. Tell them if you experience anxiety while still in an immobilization device. Your doctor can prescribe medicine to help you relax.

After the simulation in your first session, your radiation therapy team will review your information and design a treatment plan. Computer software helps the team develop the plan.

Who receives radiation therapy?

More than half of persons with cancer receive radiation therapy. This is sometimes the only cancer treatment needed, and sometimes it is used with other types of treatment. The decision to use radiation therapy depends on the type and stage of cancer and other health problems the patient may have.

What are the goals of radiation therapy?

Most types of radiation therapy do not reach all parts of the body, which means that they do not help treat cancer that has spread to many parts of the body. Still, radiation therapy can be used to treat many types of cancer, also alone or in combination with other treatments. While it is important to remember that every cancer and every person is different, radiation is often the treatment of choice for the following purposes.

To cure or reduce early-stage cancer

Some cancers are very sensitive to radiation. Radiation can be used alone in these cases to make cancer shrink or go away completely. In some cases, chemotherapy or other anticancer drugs may be given first. For other cancers, radiation may be used before surgery to shrink the tumor (this is called preoperative therapy or neoadjuvant therapy), or after surgery to help keep cancer from coming back (called adjuvant therapy). For certain cancers that can be cured by radiation or surgery, radiation may be the preferred treatment. This is because radiation can cause less damage and the affected body part is more likely to function as it should after treatment.

For approximate types of cancer, radiation and chemotherapy or other types of anticancer drugs can be used composed. Sure drugs (called radiosensitizers) help the radiation work better by making cancer cells more sensitive to radiation. Exploration has shown that when anticancer drugs and radiation are given together for sure types of cancer, they can help each other work even better than if they were given alone. However, one drawback is that side effects are often worse when taken together.


The first step in radiation treatment is to determine if it is the right form of treatment for you. Your doctor will also determine the dose amounts and the frequency of radiation that is best suited to your type and stage of cancer. Sometimes your doctor may decide that radiation therapy is more appropriate for use at a later stage, so you may receive other cancer treatments first. It usually includes the steps shown below.

  • Radiation simulation
  • You will lie on the same type of table that will be used for your treatment
  • Standing still at the proper angle is very important to successful treatment, so your healthcare team can use cushions and restraints to position you at the best angle for treatment.
  • Then you will have CT scans or X-rays to determine the full extent of your cancer and where the radiation should be focused.
  • After determining the best location for radiation treatment, your treatment team will mark the area with a very small tattoo. This tattoo is usually the size of a freckle. In certain cases, a permanent tattoo is not necessary.
  • You are now prepared to begin radiation therapy

Radiation therapy techniques

Radiation can damage normal cells. The radiation must be directed at cancer. An advanced form of three-dimensional (3-D) conformal radiation, called intensity-modulated radiation therapy, or IMRT, more precisely matches the dose to tumors, allowing safer delivery of higher doses of radiation.

Other techniques that allow ultra-precise doses of radiation to tumors include stereotactic radiosurgery, which uses 3-D imaging to determine the exact coordinates of a tumor. Gamma rays or highly focused X-rays then converge on the tumor to treat it. The Gamma KnifeĀ® is a treatment option that uses radioactive azure sources to focus numerous beams of radiation on a small area. Linear accelerators can also be used to carry stereotactic radiation therapy to the brain. Other parts of the body can be treated with stereotaxic body radiation therapy (SBRT). Emerging areas for SBRT use include lung, liver, and bone.

Image-guided radiation therapy (IGRT) is often used in conjunction with IMRT to ensure that radiation is delivered to the planned area. IGRT involves performing a CT scan at the time of radiation treatment to ensure that the target is aligned in the correct location. IGRT can countenance adjustments during treatment in areas of the body that are prone to drive, such as the lungs and tumors located near critical organs and tissues.

Radiation can also be used to cut off blood flow to a tumor in vascular organs such as the liver. For example, radioembolization uses microspheres filled with radioactive isotopes to block a tumor’s blood supply and deprive it of blood.

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