Radiation therapy is the use of high-energy x-rays or other particles such as photons to destroy cancer cells. Radiation therapy is administered by a radiation oncologist, who is a doctor who specialises in giving radiation therapy to treat cancer.

Possible side-effects from radiation therapy may include mild nausea, skin reactions, fatigue, and loose bowel movements, depending on which part of the body is receiving radiation. Most side-effects disappear again soon after treatment is finished.

What is Radiation?

Radiation describes the way energy moves from one place to another; this can either be  in the form of particles such as protons or in the form of waves like x-rays or visible light.

The various types of radiation are grouped according to how much energy they contain:

  • Low Energy Radiation like radio waves and heat, is known as non-ionising radiation.
  • High Energy Radiation like ultraviolet (UV) light from the sun and x-rays, is known as ionising radiation because it has enough energy to break chemical bonds and knock electrons (negatively charged particles) out of atoms. When these changes take place in cells, it can sometimes cause enough damage to kill the cells. As a result, such high-energy x-rays or other particles can be used to destroy cancer cells in a treatment called radiation therapy.

Radiation as Therapy

Radiation oncologists oversee radiation therapy, which generally consists of a specific number of treatments administered over a set period of time. The goal of radiation therapy is to destroy cancer cells without harming nearby healthy tissue.

Radiation therapy can be used as the main treatment or as an adjuvant therapy (treatment that is administered after the main treatment to target any potential remaining cancer cells).

Radiation therapy can also be used to shrink tumours and reduce pressure, pain, and other symptoms of cancer (palliative radiation therapy) when it is not possible to completely eliminate the disease.

More than half of all individuals with cancer will receive some type of radiation therapy. In some cases, radiation therapy on its own is an effective treatment, but other types of cancer respond best to combination treatment approaches that may include radiation plus surgery, chemotherapy, or immunotherapy.

Types of Radiation Therapy

The most common type of radiation treatment is called external-beam radiation therapy, which is radiation given from a machine outside the body.

When radiation treatment is given using implants, it is called internal radiation therapy or Brachytherapy. A radiation therapy regimen usually consists of a specific number of treatments given over a set period of time.

External-Beam Radiation Therapy

External-Beam Radiation Therapy is the most common type of radiation treatment used; it is possible to treat large areas of the body with this type of radiation if necessary.

The machine used to create the radiation beam is called a linear accelerator or linac. Computers with special software are used to adjust the size and shape of the beam and to direct it to target the tumour while avoiding healthy tissue surrounding the cancer cells. External-beam radiation therapy does not make one radioactive.

Types of external-beam radiation therapy include:

  • Three-Dimensional Conformal RadiationTherapy (3D-CRT): Special computers create detailed three-dimensional pictures of the cancer, which allows the treatment team to aim the radiation more precisely; higher doses of radiation can bu used while the risk of damaging healthy tissue is reduced. Studies have shown that 3D-CRT can lower the risk of complications and side effects, such as damage to the salivary glands of individuals with head and neck cancer who are treated with radiation therapy.
  • Intensity Modulated Radiation Therapy (IMRT): IMRT is able to better direct the radiation dose at the tumour by precisely varying the intensity of the beam under strict computer guidance; this means IMRT protects healthy tissues from radiation better than 3D-CRT does.
  • Proton Beam Therapy: Proton Beam Therapy uses protons rather than x-rays to treat certain cancers. Protons are parts of atoms that can destroy cancer cells at high energy . According to research, directing protons at a tumour decreases the amount of radiation delivered to the surrounding healthy tissue, which greatly reduces the damage to that tissue. Proton Beam Therapy is relatively new and requires highly specialised equipment, so is not available at every medical center.
  • Stereotactic Radiation Therapy: Stereotactic Radiation Therapy delivers a large, precise radiation dose to a small tumour area; this precision requires that the patient remain extremely still. Head frames or individual body moulds are sometimes used to limit movement, especially in children. Stereotactic radiation therapy is generally administered as a single treatment, but some patients may need up to five treatments.

Internal Radiation Therapy (Brachytherapy)

Internal Radiation Therapy is also known as Brachytherapy, and involves placing radioactive material into the cancer itself or into the tissue surrounding it. These radioactive implants may be permanent or temporary and may require a hospital stay.

  • Permanent implants are tiny steel capsules approximately the size of a grain of rice that contain radioactive material; they are placed inside the body at the tumour site. These capsules deliver most of the radiation around the area of the implant; some radiation may be released from the patient’s body however, which means that the patient must take special precautions to protect others from radiation exposure while the capsules are still active. The implant loses its radioactivity over time, but the inactive seeds remain in the body.
  • Temporary implants are where the radiation is delivered via needles, catheters or specialised applicators that kept in the body for a specific amount of time; this ranges between a few minutes and a few days. Most temporary implant procedures deliver radiation for just a few minutes; if it is any longer, the patient will remain in a private room while the implants are in place to limit others’ exposure to the radiation.

Both temporary and permanent placement of radioactive sources in the body may require anaesthesia (medication to block the awareness of pain) and a brief hospital stay. These treatments may be repeated across a number of days or weeks. Most patients feel little to no discomfort during the treatment, but some may experience weakness or nausea from the anaesthesia.

Radiation Therapy Side-Effects

Those undergoing Radiation Therapy may sometimes experience some Side-Effects.

Relieving side-effects, also known as palliative caresupportive care, or symptom management, is an important part of total cancer care and treatment, which is why you should discuss any symptoms your child is experiencing, new symptoms and changes in symptoms with their Oncology Team so that they can work out a regimen of palliative or supportive care for them.


Please note that the Little Fighters Cancer Trust shares information regarding various types of cancer treatments on this blog merely for informational use. LFCT does not endorse or promote any specific cancer treatments – we believe that the public should be informed but that the option is theirs to take as to what treatments are to be used.

Always consult your medical practitioner prior to taking any other medication, natural or otherwise.