# Respiratory motion management (4D-CT, gating, breath-hold, tracking)

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

## TL;DR

Ways of dealing with tumours that move as the patient breathes: image the motion, treat only in part of the breathing cycle, hold the breath, or chase the tumour with the beam.

## Summary

Lung, liver, pancreas and breast targets move by a centimetre or more with breathing. Four-dimensional CT captures the motion so the target volume can include it or be defined at one phase; respiratory gating switches the beam on only during that phase; deep-inspiration breath-hold freezes the anatomy and, in left breast treatment, moves the heart away from the beam; and real-time tracking with fiducial markers or MRI moves the beam or couch with the tumour. Motion management is what makes stereotactic body radiotherapy safe for small mobile targets.

## Fields

- Kind: Technology
- Status: established
- Last checked: 2026-09-16
- Tags: radiation-wave1
- Principle: Measure or constrain respiratory motion so the planned dose lands on the target rather than on the tissue it moves through.
- Since: 2000
- Strengths: Smaller margins and less normal tissue dose; Enables stereotactic treatment of moving targets; Reduces heart dose in breast radiotherapy
- Limitations: Longer sessions; Some patients cannot hold their breath; Fiducial placement is invasive

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Respiratory_gating

## Connected records

- cancers: [Hepatocellular carcinoma](https://onco.cc/cancers/hcc/), [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/), [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/)
- fronts: [Radiation Therapy](https://onco.cc/fronts/radiation/)
- technologies: [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/), [MR-guided adaptive radiotherapy](https://onco.cc/technologies/mr-linac/), [SBRT / SABR (stereotactic radiotherapy)](https://onco.cc/technologies/sbrt/)
- terms: [Deep inspiration breath-hold (DIBH)](https://onco.cc/terms/deep-inspiration-breath-hold/), [Fiducial markers](https://onco.cc/terms/fiducial-markers/)
- trials: [CHISEL (TROG 09.02)](https://onco.cc/trials/chisel/)

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JSON: https://onco.cc/api/v1/entities/respiratory-motion-management.json