LINAC and Proton Therapy Shield Design

Radiotherapy treats tumours by targeting and killing cancerous cells using radiation. As well as an effective means of treatment, it is also a fast-growing area of research that has produced new forms of radiotherapy such as proton therapy and ion therapy. All these forms of radiotherapy make use of a particle accelerator to accurately aim beams of ionising radiation into the patient.

What is THE LINAC and Proton Therapy Shield Design?

Radiotherapy makes use of particle accelerators in order to accurately deliver sufficiently high doses of radiation to kill cancerous cells but localised to sufficiently small areas to minimise damage to healthy cells.

Because of the energy and intensity of the particle beam in conventional medical electron linear accelerators (LINACs), the radiation emitted when the electrons ‘slow down’ within the patient; whilst significantly less intense than that delivered to a tumour, is still significant. As such, radiation shielding is required to ensure that hospital personnel do not receive a chronic radiation dose as a result of performing many such procedures. This normally consists of a concrete bunker with either a labyrinth entrance or power assisted shield door.

The more recent developments of proton therapy and ion therapy allow more precise depth placement of radiation dose within a patient, but because of the larger energies required to deliver these particles to the required depths, they require larger LINACs. The larger LINACs require a more complex shielding arrangement and the higher energies mean higher potential radiation dose, as well as a greater neutron component of the radiation dose. This therefore has an impact on the shielding design.

Why is LINAC and Proton Therapy Shield Design Important?

Radiotherapy suites are becoming more affordable and therefore more and more hospitals are being equipped with them. It is also likely that proton and ion therapy suites will follow the same trend in decades to come.

Most countries have strict regulations regarding the amount of radiation dose people can legally be exposed to. For non-radiation workers, i.e. hospital personnel and members of the public, these limits are low. A hospital has a duty of care to its personnel, patients and visitors and part of demonstrating this duty of care is demonstrating to the relevant government health and safety board that its radiation shielding provisions are adequate.

By demonstrating that the radiotherapy suites can operate safely by implementing radiation shielding calculations and radiation protection measures at the design phase, the risk of additional cost and time lost due to disruptive corrective construction measures can be significantly reduced, or eliminated.

TÜV SÜD's Services

The TÜV SÜD radiation physics team can offer a range of services to support LINAC and proton therapy shield design, including:

• Radiation shielding design – TÜV SÜD’s radiation physics team can implement radiation protection principles from concept design, including working with the hospital Radiation Protection Advisor to establish design criteria. Calculations can then be performed to provide required materials and thicknesses. Assessment of shielding weaknesses (e.g. door gaps and services penetrations) can also be performed.