Introduction to 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 that support its use in the treatment of breast, brain, head and neck cancer, sarcoma, and other conditions.

Example Applications of SGRT with AlignRT

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 complications. 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, there are more than 10 publications that demonstrate the accuracy of the technique.

Brain

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

Two studies suggest AlignRT can deliver the same clinical outcomes as more invasive procedures, with increased patient comfort and fast treatment times.

Pediatric Patients

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

1. Darby et al. Risk of Ischemic Heart Disease in Women after Radiotherapy for Breast Cancer. N Engl J Med 2013; 368:987-998

2. Gierga 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

3. Zagar 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

4. Marks, 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)

5. Pan et al. Frameless, real-time, surface imaging-guided radiosurgery: clinical outcomes for brain metastases. Neurosurgery. 2012 Oct;71(4):844-51.

6. Pham 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.