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Stereotactic Ablative Radiotherapy (SABR)

Stereotactic radiotherapy is a highly focused and accurate treatment which involves precisely targeting multiple X-rays at a small well defined area. The aim is to destroy the cancer cells within the targeted region.

Some patients may benefit from having a specialised type of radiotherapy called stereotactic ablative radiotherapy (SABR). If only one treatment is given, it is often called stereotactic radiosurgery (SRS).

What is Stereotactic Radiotherapy?

Standard external beam radiotherapy delivers several beams of radiation to the treatment area and is usually given in daily treatment sessions over a period of weeks. SABR uses many smaller, focused beams of radiation. These beams are directed from different angles that meet at the tumour. This means that the tumour gets a high dose of radiation, while surrounding healthy tissues get a much lower dose. This lowers the risk of damage to normal cells. As a higher dose of radiation is given per session, fewer treatment sessions are required. The number of treatments can vary between one to eight treatments over a period of two weeks.

Stereotactic radiotherapy is best suited for patients with small, well-defined tumours. It is not suitable for all patients.

Conventional radiotherapy is the typical alternative treatment to SABR which can consist of 20 daily treatments over four weeks.

In Birmingham, stereotactic radiotherapy can be given on a linear accelerator (Linac), or a special robotic machine called cyberknife. Patients will be told which machine they will have their treatment on.

SABR treatment on a linear accelerator is used to treat metastatic disease including adrenal, liver and pelvic lymph nodes. CyberKnife treatment is not suitable for these areas.

When is Stereotactic Radiosurgery or Stereotactic Radiotherapy given?

  • Stereotactic radiosurgery is given in a single treatment on a weekday
  • Stereotactic ablative radiotherapy is given in three to eight treatments often on alternate days over a two week period

What needs to happen before I start Stereotactic Radiotherapy?

All patients having radiotherapy treatment need to attend a planning appointment before they start treatment.

Stereotactic planning visits are usually much longer than conventional radiotherapy planning visits, and vary from 45 minutes to several hours as planning is much more complex. 

Patients will be given an information leaflet specific to the area being treated when seen by a consultant in clinic and consenting to treatment. The leaflet will explain about the planning appointment, treatment, and any expected side effects for the area being treated.

A therapeutic radiographer will explain the procedure on arrival to the CT scanner.

Stereotactic Radiotherapy treatment

Treatment is given on a weekday, and is often given on alternate days over a two week period. Each treatment visit typically takes over 60 minutes.

Other sites of metastatic disease including adrenal, liver and pelvic lymph nodes are treated with SABR on other treatment machines such as linear accelerators, but they are not suitable for treatment on cyberknife.

SABR and cyberknife treatment is similar to standard radiotherapy:

  • treatment is painless and patients may hear the machine moving when it is switched on
  • therapy radiographers cannot stay in the room when the machine is switched on
  • patients need to keep still
  • CCTV is used to monitor patients during treatment
  • it is extremely important that patients are not pregnant, nor become pregnant during treatment
  • treatment does not make patients radioactive
  • conventional radiotherapy is the typical alternative treatment to SABR which can consist of 20 daily treatments over 4 weeks, compared to one to eight SABR treatments

Last reviewed: 05 March 2024