External Beam Radiotherapy (EBRT)

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External Beam Radiotherapy (EBRT)

External Beam Radiotherapy (EBRT) refers to radiation directed at you from outside the body. This can be delivered in a number of different ways, including via a Linear Accelerator (Linac), Cobalt or Orthovoltage units.

Treatment is painless and non-invasive and is similar to having an x-ray taken. The patient must remain as still as possible during treatment. The treatment time for each patient differs depending on the dose of radiation prescribed, it can take up to twenty minutes to deliver the treatment. The radiation therapists bring the patient into the treatment room and set the patient up they leave the room and go to the control area to switch on the beam. During the treatment the patient is alone in the treatment room but the radiation therapists constantly monitor them via cameras in the treatment rooms.

Depending on the area to be targeted, different methods of delivering treatment are chosen and your team will discuss your case with you in detail before starting treatment.

There are five different forms of external beam radiotherapy;

Intensity-Modulated Radiotherapy (IMRT)

Intensity-Modulated Radiotherapy (IMRT) is a form of external beam radiotherapy that uses linear accelerators to deliver multiple small radiation beams to a tumour.

It allows shaping of the radiation dose to improve the targeting of the tumour and minimise the radiation dose to the surrounding normal organs.

This therapy is mainly used where a tumour is situated close to normal tissues that have a high risk of damage from radiation.

IMRT is available - where necessary - in all St Luke's Radiation Oncology Network (S.L.R.O.N.) centres.

Volumetric-Modulated Arc Therapy (VMAT) / RapidArcTM

Volumetric-Modulated Arc Therapy (VMAT) is a newer form of IMRT that delivers external beam radiotherapy through a continually rotating radiation source that encircles the patient.

It makes changes in the speed of rotation, the shape of the radiation field and the strength of radiation. This results in the faster delivery of precisely targeted radiation doses.

VMAT - in the form of RapidArcTM - is currently available in the St. James' and Beaumont centres.

Image-Guided Radiotherapy (IGRT)

Image-Guided Radiotherapy (IGRT) uses imaging with x-ray or CT during a course of radiation.

This continually reassesses the movement of the patient and of the organs within the body to allow more precise targeting of the tumour.

IGRT is available in all centres in the St. Luke's Network.

Stereotactic Radiosurgery (SRS)

Stereotactic radiosurgery (SRS) is used in the treatment of tumours in the head (intracranial).

It uses multiple small beams to precisely target the region to be treated. The head is very carefully immobilised using an individualised frame that fits around the head and minimises movement during treatment.

Like brachytherapy, it may be used alone or in combination with surgery or external beam radiotherapy.

There are many ways of delivering SRS, including with Gamma KnifeTM, CyberKnifeTM and linear accelerators.

In the St. Luke's Network, all stereotactic radiosurgery is currently delivered in the Rathgar centre using linear accelerators.

Stereotactic Body Radiotherapy (SBRT)

Stereotactic body radiotherapy is a specialised type of external beam radiotherapy that allows the delivery of high doses of radiation to small tumours, while minimising the dose received by the surrounding normal tissues. It is used most frequently to treat early lung cancers.

Treatment times are generally longer than with standard EBRT and imaging with CT is required prior to each treatment session.

SBRT will shortly be available in the St. Luke's Network. Until it is, all patients requiring this type of treatment are referred to a local centre where specialised facilities are available.