# Breathing motion in lung and upper abdominal radiotherapy: 4D CT, gating, breath-hold and compression

Source: https://onco.cc/protocols/respiratory-motion-management-4d-ct-and-gating/  
OnCo record `respiratory-motion-management-4d-ct-and-gating` (Protocol). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Tumours in the lung, liver and upper abdomen move as you breathe. At the planning scan the team usually records the whole breathing cycle (4D CT) to see how far the tumour moves. They then plan to cover that movement, or reduce it by asking you to hold your breath, pressing gently on your tummy, or switching the beam on only at one point in each breath. They practise the breathing with you first.

## Summary

AAPM Task Group 76 (Report 91, 2006) recommends measuring three-dimensional tumour motion for each patient where breathing motion may matter, over several breathing cycles; if motion cannot be measured, the prudent course is to assume it is significant and use motion management. Motion management is recommended for consideration when the range of motion exceeds 5 mm in any direction, or when it gives significant normal tissue sparing; the 5 mm threshold may be lower for SBRT. A measured motion should be built into the margin: the whole range if no device is used (an internal target volume), only the residual motion if one is. The patient is coached at simulation and on the first treatment day; a back-up CT without breathing requirements is taken in case the patient cannot comply. TG-76 recommends a qualified physicist at simulation sessions using motion devices and at least the first treatment, the most accurate dose calculation available in lung, written QA for every step, and frequent verification images of the diaphragm or tumour (daily for the first few treatments, then at least weekly). MPPG 9.b (2025) requires 4D CT for thoracic and abdominal SBRT and end-to-end testing with a moving phantom. In the TG-324 survey of AAPM members (2020), 95% used motion management for thoracic and abdominal sites, 60% the internal target volume method, 25% breath-hold or compression and 13% gating or tracking. TG-76 is 20 years old and predates routine cone-beam CT and surface guidance; no newer AAPM report replaces it.

## Fields

- Kind: Protocol
- Last checked: 2026-11-11
- Also known as: respiratory motion management; 4D CT; 4DCT; four-dimensional CT; respiratory gating; abdominal compression; internal target volume; ITV; tumour tracking; TG-76; breath-hold for lung

## Connected records

- protocols: [Deep inspiration breath-hold for left-sided breast radiotherapy](https://onco.cc/protocols/breath-hold-left-breast-radiotherapy/), [Radiotherapy planning scan (CT simulation): positioning, skin marks and what the patient does](https://onco.cc/protocols/radiotherapy-planning-ct-simulation/), [Stereotactic radiosurgery and SBRT: planning and delivery safeguards](https://onco.cc/protocols/stereotactic-radiosurgery-and-sbrt-delivery-safeguards/)
- cancers: [Hepatocellular carcinoma](https://onco.cc/cancers/hcc/), [Lung cancer (all types)](https://onco.cc/cancers/lung-cancer/), [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/)
- technologies: [CT (computed tomography)](https://onco.cc/technologies/ct/), [CyberKnife robotic radiosurgery](https://onco.cc/technologies/cyberknife/), [In-room imaging for radiotherapy (cone-beam CT, ExacTrac, CT-on-rails, HyperSight)](https://onco.cc/technologies/in-room-imaging-systems/), [Respiratory gating and tumour tracking systems (RPM, ABC, Calypso, Synchrony)](https://onco.cc/technologies/respiratory-gating-tumour-tracking-systems/), [Respiratory motion management (4D-CT, gating, breath-hold, tracking)](https://onco.cc/technologies/respiratory-motion-management/), [SBRT / SABR (stereotactic radiotherapy)](https://onco.cc/technologies/sbrt/), [Surface-guided radiotherapy (SGRT)](https://onco.cc/technologies/surface-guided-radiotherapy/)
- terms: [Fiducial markers](https://onco.cc/terms/fiducial-markers/), [GTV, CTV and PTV (target volumes)](https://onco.cc/terms/planning-target-volume/), [Radiotherapy](https://onco.cc/terms/radiotherapy/)

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