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The treatment room

Introducing the treatment room

In this video, Claire is using a piece of technology called VERT or Virtual Environment of a Radiotherapy Treatment Room, to show what a treatment room looks like.

This technology is often used to educate radiation therapy students here in Trinity College.

Some of the terms used in the video include:

Linear accelerator

  • Radiation therapy is generated by a large machine called a linear accelerator which delivers high energy x-rays or electron beams to a patient’s tumour.

Treatment couch

  • All patients being treated with radiation therapy must lie on a narrow bed which is known as the treatment couch. Most modern treatment couches are made from a carbon material which allows photon energies to travel through the bed and treat the patient i.e. they have a low attenuation of the beam.


  • The gantry is the main body of the linear accelerator. It can move 360 degrees around the treatment couch and is noisy when moving. The radiation therapists can move the gantry when they are both in the treatment room and also outside the treatment room. In order to facilitate the movement of the gantry, the treatment couch is deliberately quite narrow.


  • The circular part of the linear accelerator at the head of the gantry is called the collimator. This too can move 360 degrees.

Light field size

  • The light field shows the radiation therapists (RTTs) the size, shape and orientation of the treatment beam.

Optical Distance Indicator (ODI)

  • This a measurement tool that can be used daily to take various measurements. These measurements are compared to your personalised treatment plan to ensure that the treatment is correctly delivered.
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An Introduction to Radiation Oncology: From Diagnosis to Survivorship

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