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Types of Radiation Therapy
There are several different types of radiation therapy. The type that may be recommended for you depends on a variety of factors, such as your cancer, its stage, and your treatment goals.
Radiation therapy is a type of cancer treatment. It uses high doses of radiation to:
kill cancer cells
slow the growth of cancer cells
ease cancer symptoms like bone pain
Researchers estimate that over 30% of people with cancer in the United States receive radiation therapy as a part of their first-line cancer treatment. One-half of people with cancer have radiation therapy at some point in their treatment journey.
This article examines the different types of radiation therapy, how they work, and what they're typically used to treat.
What is external beam radiation therapy?
External beam radiation therapy (EBRT) is the most common type of radiation therapy. It can be used to treat a vast variety of cancers.
In EBRT, a specialized machine is used to aim high-energy particles directly at the cancer.
The machines used to deliver EBRT can resemble a larger version of an X-ray machine or a CT scanner. The most common kind of machine used for EBRT is a linear accelerator.
EBRT is a local treatment, which means it only affects the part of your body affected by cancer. For example, if you're being treated for breast cancer, EBRT will only be focused on the tumor in your breast and not your entire body.
EBRT often involves daily radiation therapy 5 days a week for several weeks. The exact number of weeks you have EBRT can depend on factors like the type of cancer you have, your treatment goals, and the radiation dose used.
You typically have EBRT as an outpatient, meaning that you can return home after your treatment sessions.
Types of particles used for EBRT
Currently, there are several different types of particles used for EBRT, these include:
protons
photons
electrons
Photons
Most EBRT machines use photons, which can reach cancers deep within your body. Photons are the same type of particle used in X-rays. However, the dose of photons received during EBRT is much stronger.
There are several subtypes of photon-based EBRT to be aware of.
Three-dimensional conformal radiation therapy (3D-CRT)
3D-CRT delivers radiation from several different directions and uses imaging like CT scans MRI scans, or PET scans to accurately pinpoint the cancer. A computer program uses the imaging information to develop a treatment plan specific to your tumor.
Intensity-modulated radiation therapy (IMRT)
IMRT is similar to 3D-CRT. However, it uses more numerous, smaller radiation beams. The intensity of these can also be adjusted so that some areas of a tumor get higher doses of radiation than others.
Volumetric modulated arc therapy (VMAT) is a newer way of giving IMRT. In VMAT, the radiation machine moves around you and can adjust the radiation beam during your treatment.
Image-guided radiation therapy (IGRT)
In IGRT, imaging is used to plan treatment, as well as to direct the radiation during a treatment session.
Stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT)
SRS directs a very focused beam containing a high dose of radiation at a tumor and can be used if conventional surgery isn't an option. It's often used for tumors in the brain and other areas inside the skull.
SBRT is essentially the same as SRS, but is given outside of the brain. As such, it may be used for tumors affecting tissues, including but not limited to the lungs, liver, and prostate.
Intraoperative radiation therapy (IORT)
IORT is when you receive radiation during a surgical procedure to treat your cancer. It can be used if a surgeon cannot completely remove a tumor or if the cancer has a high risk of coming back.
Protons
Protons are positively charged particles that can also reach cancers deep in the body. Compared to photons, protons are less likely to scatter within the body, which means healthy tissue is less likely to be exposed to radiation.
Proton-based EBRT can be used to treat cancers affecting the:
eyes
prostate
liver
lung
brain and spinal cord
skull base
head and neck
Electrons
Electrons are negatively charged particles. Compared to photons and protons, they cannot travel that far in the body. Because of this, electrons are typically used for cancers close to the surface of the body, such as those on the skin.
What is internal radiation therapy?
Internal radiation therapy (brachytherapy) is when a radiation source is placed inside your body. This is in contrast to EBRT, where the radiation source is located outside of your body.
However, like EBRT, internal radiation therapy is a type of local treatment, allowing radiation to be inside or near your cancer without affecting other areas of the body.
There are several types of cancer for which internal radiation therapy may be used. Some of the most common include:
It's also possible that internal radiation therapy may be recommended for certain types of:
penile cancer
urethral cancer
head and neck cancer
eye cancer
sarcoma
Radiation sources for internal radiation therapy are implanted during a procedure that uses a catheter or applicator and may involve either general or local anesthesia. Implants can come in a variety of forms, including:
seeds, pellets, or capsules
discs or plaques
tubes or wires
There are three general types of internal radiation therapy.
Low dose internal radiation therapy
A low dose internal radiation therapy implant can typically stay in place from 1 to 7 days, after which it's removed.
High dose internal radiation therapy
In high dose internal radiation therapy, an implant is only left in place for 10 to 20 minutes before being removed. You may have this type of internal radiation therapy twice daily for up to five days or once weekly for up to five weeks.
Permanent internal radiation therapy
A permanent internal radiation therapy implant remains in your body for the rest of your life. The level of radiation from the implant decreases gradually over time.
What is systemic radiation therapy?
In contrast to EBRT and internal radiation therapy, systemic radiation therapy is when the radiation travels throughout your body.
This type of radiation therapy uses drugs to deliver the radiation to the cancer. These can be given by mouth or into your bloodstream via an IV.
There are two types of systemic radiation therapy.
Radioimmunotherapy
Radioimmunotherapy uses radioactive material attached to a monoclonal antibody that's specific to certain types of cancer cells. When the antibody binds to the cancer cell, it delivers the radiation.
This type of systemic radiation therapy can be used for neuroendocrine tumors, prostate cancer, and some kinds of lymphoma.
Peptide receptor radionucleotide therapy (PRRT)
PRRT utilizes radioactive material that's attached to a short protein (peptide). It targets cancer cells with receptors for this peptide. The peptide delivers the radiation when it binds to its receptor on the cancer cell.
PRRT is used for neuroendocrine tumors.
Takeaway
There are several types of radiation therapy. Additionally, each type of radiation therapy has different subtypes.
The type of radiation therapy that's recommended for you can depend on factors like the type of cancer you have, the stage of your cancer, your treatment goals, and your age and overall health.
If radiation therapy is part of your cancer treatment plan, be sure to speak to your doctor about your specific treatment. They can give you more information on things like the procedures involved, how long your treatment will last, and what types of side effects to expect.
