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CancerQuest > Introduction to Patient Information > An Introduction to Cancer Treatments > Introduction to Radiation Therapy > Types of Radiation Therapy

Types of Radiation Therapy

Radiation can harm both cancerous and normal tissues, the treatment is based on the fact that fast growing cells, such as those found in tumors, are more sensitive to radiation damage. The radiotherapy technique used depends on the type, extent and location of the cancer, and the goal of treatment.

Internal radiation called brachytherapy is the process of implanting radioactive material onto or near the tumor or placing radioactive sources into the body. It can be temporary or permanent. Depending on the location of the implant the treatment may be handled as either an in- or out-patient procedure. ⁽¹⁾

External radiation therapy utilizes a machine to deliver radiation to the tumor. This therapy is primarily an outpatient treatment. Most protocols last approximately 4-7 weeks with treatments given 5 days per week. ⁽¹⁾

Both internal and external therapies act to destroy the ability of the cancer cells to reproduce. There are several different types of radiation that may be utilized:

Photon radiation uses high energy rays composed of particles of energy called photons. Photon radiation acts by disrupting the molecules of the target cells, which interferes with normal cell functions. There are several types of photon radiation:

• Gamma rays: produced by the breakdown of radioactive isotopes of elements such as Cobalt-60 and radium
• X-rays: originate from machines that excite electrons using cathode ray tubes or linear accelerators. ⁽²⁾

Particle radiation uses subatomic particles, particles that make up an atom, to disrupt cells. There has been limited use of particle radiotherapy, such as proton therapy, in clinical practice due to the complex and costly equipment needed for its production, but there are some advantages for using this method. It can deliver higher dose of radiation to the target volumes with less damage to the surrounding tissue. This should allow for treatment with fewer margins, more effective treatments and reduced side effects.⁽²⁾

References for this page:

1. Emory Radiation Oncology [http://www.emoryradiationoncology.org]
2. Radiation Therapy. Lica, Lorraine. (April 2002).