Surface Guided Radiation Therapy

What is Surface Guided Radiation Therapy (SGRT)?

Surface Guided Radiation Therapy (SGRT) is a rapidly growing technique which uses stereo vision technology to track patients’ surface in 3D, for both setup and motion management during radiotherapy. SGRT can be used for many types of radiation therapy. There are numerous publications which support its use in the treatment of breast, brain, head and neck cancer, sarcoma, and other conditions.

The benefits of SGRT

SGRT can help in the following ways, which lead to many application-specific benefits.

  • Setup: SGRT helps speed up and improve the accuracy of setup.
  • Treatment: SGRT can reduce the need for immobilisation while helping to ensure the patient is in the correct position for treatment in all 6 degrees of freedom.
  • 4D CT: SGRT enables contactless, non-invasive reconstruction of 4D CT data.

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Applications of SGRT

Left Breast cancer and accurate breath hold treatment

Radiation therapy has been shown to be a highly effective treatment for breast cancer. But the proximity of the left breast to the heart leaves the heart vulnerable to radiation exposure. This has been shown to lead to serious long-term cardiac complications1. In one study of patients treated for left breast cancer, 27% exhibited cardiac perfusion defects within six months¹.

Many centers are beginning to have patients use a Deep Inspiration Breath Hold (DIBH) to move the heart away from the breast during therapy. However, achieving this can be challenging². Patients breathe in different ways at different times, and may arch their back to simulate a deep breath in. These different movements can appear similar to a patient’s true breath hold, but do not necessarily separate the heart from the breast.

A recent study³ showed that AlignRT + DIBH effectively prevented radiation-induced abnormalities in blood flow to the heart. Of the breast cancer patients treated, 0% showed these abnormalities after six months. This compares to a previous study without AlignRT or DIBH, where 27% of patients showed new abnormalities in blood flow to the heart 6 months after radiation therapy⁴. Additionally, 10 publications demonstrate the accuracy of the technique.


Data⁵,⁶ suggests that SGRT in SRS gives similar patient outcomes, with better patient comfort and fast treatment times, compared to other commonly-used, more invasive technologies.

Head and Neck

In head and neck cancer, data⁷,⁸ suggests SGRT can enhance setup and positional accuracy during treatment.

Pediatric patients

SGRT offers many benefits in paediatrics, including enhancing setup, avoiding tattoos and reducing the need for general anaesthetic in children.


The SGRT Community

Click here to visit and learn about the SGRT Community, aiming to spread clinical awareness and share best practices for SGRT. (Link opens in new tab)

¹Darby et al. Risk of Ischemic Heart Disease in Women after Radiotherapy for Breast Cancer. N Engl J Med 2013; 368:987-998
²Gierga et al. A Voluntary Breath-Hold Treatment Technique for the Left Breast With Unfavorable Cardiac Anatomy Using Surface Imaging. Int J Radiat Oncol Biol Phys. 2012 Dec 1;84(5):e663-8
³Zagar et al. Prospective Assessment of Deep Inspiration Breath Hold to Prevent Radiation Associated Cardiac Perfusion Defects in Patients With Left-Sided Breast Cancer J Appl Clin Med Phys. 2015 ;93:3S 2027
⁴Marks, L. B. et al. The incidence and functional consequences of RT‑associated cardiac perfusion defects. Int. J. Radiat. Oncol. Biol. Phys. 63, 214–223 (2005)
⁵Pan et al. Frameless, real-time, surface imaging-guided radiosurgery: clinical outcomes for brain metastases. Neurosurgery. 2012 Oct;71(4):844-51.
⁶Pham et al. Frameless, real-time, surface imaging-guided radiosurgery: update on clinical outcomes for brain metastases. Trans. Cancer Res, 3, 4, 351-357, August, 2014.
⁷Zhao et al. Feasibility of Open Mask Immobilization with Optical Imaging Guidance (OIG) for H&N Radiotherapy. AAPM Abstract SU-F-J-18 2016
⁸Gopan O, Wu Q. Evaluation of the accuracy of a 3D surface imaging system for patient setup in head and neck cancer radiotherapy. Int J Radiat Oncol Biol Phys. 2012 Oct 1;84(2):547-52

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Join a community of like-minded radiation oncology professionals, working together to adopt and advance the use of non-ionizing surface guided imaging. Click ‘join now’ to be visit and learn more about the SGRT Community.

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