External Beam Radiation Therapy (EBRT) is a common form of radiation treatment in which a machine outside the body directs high-energy radiation towards a tumour or a defined treatment area. It is non-invasive and does not require radioactive material to be placed inside the body.
EBRT is most commonly delivered using a linear accelerator, which produces high-energy X-rays, also called photons. Electron beams may be used for selected tumours close to the body’s surface. Treatment is carefully planned to deliver the prescribed dose to the cancer while limiting radiation exposure to nearby healthy tissue.
EBRT may be used to cure or control cancer, reduce the risk of cancer returning after surgery, shrink a tumour before surgery or relieve symptoms such as pain, bleeding or pressure. It may be given alone or combined with surgery, chemotherapy, immunotherapy or other cancer treatments.
- Tumours that can be treated effectively with radiation as the main treatment
- Cancer remaining after surgery or when there is a risk of microscopic cancer cells being left behind
- Tumours that need to be reduced in size before surgery
- Cancers being treated with radiation and chemotherapy together
- Patients who are not suitable for surgery because of the tumour’s location, other medical conditions or overall health
- Locally advanced cancers that require treatment to the tumour and nearby lymph nodes
- Cancer that has returned in or near a previously treated area, where further radiation is considered safe
- Cancer that has spread to the bones, brain or other organs
- Tumours causing pain, bleeding, obstruction, pressure or other symptoms
- Selected non-cancerous conditions for which radiation therapy is clinically appropriate
How EBRT Is Performed
Before Treatment
The radiation oncologist reviews the diagnosis, biopsy findings, imaging, previous treatments and general health.
The treatment plan may be discussed with surgeons, medical oncologists and other specialists.
A planning or simulation CT scan is performed with the patient in the treatment position.
MRI, PET-CT or other imaging may be combined with the planning scan to define the tumour and nearby organs.
A customised mask, mould, cushion or other immobilisation device may be prepared to help maintain the same position during every session.
Small reference marks may be placed on the skin or immobilisation device to guide positioning.
Additional preparation, such as maintaining a full bladder, emptying the bowel or controlling breathing, may be required depending on the treatment area.
The radiation oncologist defines the treatment area and prescribed dose, while the medical physicist and planning team calculate the safest beam arrangement.
The plan undergoes safety and quality checks before treatment begins.
During Treatment
The patient is positioned on the treatment table using the customised supports and reference marks.
Imaging may be performed before or during treatment to confirm that the patient and treatment area are correctly positioned.
The treatment machine moves around the patient and directs radiation towards the planned area from one or more angles.
The machine may come close to the patient but does not touch them.
The patient must remain still but can breathe normally unless specific breathing instructions are given.
The radiation cannot be seen or felt, and the treatment itself is painless.
The treatment team monitors the patient from a nearby control room and can communicate with them throughout the session.
Most appointments take approximately 15 to 30 minutes, although the actual radiation delivery usually lasts only a few minutes.
Treatment may be delivered in a single session or over several sessions. Many treatment courses are given five days a week over a few days or several weeks.
After Treatment
Most patients can return home immediately after each session.
The patient is not radioactive and can safely be around family members, children and pregnant women.
Many patients can continue routine activities, work or light exercise, depending on the treatment area and how they feel.
Side effects may develop gradually as treatment progresses and may continue temporarily after treatment ends.
Medicines, skin care, nutritional support or rehabilitation may be recommended to manage treatment-related effects.
The treatment team reviews the patient regularly during the course and adjusts supportive care when required.
Follow-up appointments are planned to monitor recovery and evaluate the treatment response.
Imaging or other tests may be performed after an appropriate interval, as the effects of radiation continue after the final session.
Potential Benefits of EBRT
- Treatment of many different cancer types and body areas
- Non-invasive treatment without a surgical incision
- Precisely planned delivery of radiation to the tumour or treatment area
- The ability to treat the tumour and nearby areas at risk of containing microscopic cancer cells
- Use as the main treatment for selected cancers
- Reduction of the risk of cancer returning after surgery
- Shrinkage of certain tumours before surgery
- The ability to combine radiation with chemotherapy or other cancer treatments
- Preservation of an organ or its function in selected patients
- Relief of symptoms such as pain, bleeding, pressure or obstruction
- Outpatient treatment for most patients
Side Effects of Proton Therapy
- Tiredness or fatigue
- Redness, dryness, itching, tenderness or darkening of the skin over the treated area
- Temporary hair loss limited to the area receiving radiation
- Reduced appetite
- Nausea or digestive discomfort when the abdomen or pelvis is treated
- Mouth soreness, dry mouth, taste changes or difficulty swallowing during treatment to the head and neck
- Headache, nausea or swelling-related symptoms during treatment to the brain
- Cough, breathlessness or discomfort when the chest is treated
- Changes in bowel or bladder habits during treatment to the abdomen or pelvis
- Temporary changes in blood cell counts when larger areas containing bone marrow are treated
- Delayed effects involving the tissues or organs near the treated area, which will be discussed according to the individual treatment plan
- A small long-term risk of developing another cancer related to radiation exposure
