# Surface-guided radiotherapy (SGRT)

Source: https://onco.cc/technologies/surface-guided-radiotherapy/  
OnCo record `surface-guided-radiotherapy` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Cameras track the patient's skin surface in three dimensions during treatment, replacing tattoos and pausing the beam if the patient moves.

## Summary

Optical surface tracking systems project structured light onto the patient and compare the reconstructed surface with the planned one many times a second. They set up the patient without permanent skin tattoos, monitor motion throughout the beam and gate delivery during breath-hold. Surface guidance is now routine in breast radiotherapy, where deep-inspiration breath-hold moves the heart out of the field, and in radiosurgery with open face masks.

## Fields

- Kind: Technology
- Status: established
- Last checked: 2026-09-16
- Tags: radiation-wave1
- Principle: Real-time comparison of the patient's 3D surface with a reference surface drives setup corrections and beam gating.
- Since: 2010
- Strengths: No tattoos or extra radiation; Continuous motion monitoring; Enables breath-hold treatment
- Limitations: Surface does not always track internal anatomy; Struggles with large body habitus changes; Extra hardware and commissioning

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Image-guided_radiation_therapy

## Connected records

- cancers: [HER2-positive breast cancer](https://onco.cc/cancers/breast-her2-positive/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- fronts: [Radiation Therapy](https://onco.cc/fronts/radiation/)
- technologies: [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/)
- terms: [Deep inspiration breath-hold (DIBH)](https://onco.cc/terms/deep-inspiration-breath-hold/)

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