# Fiducial markers

Source: https://onco.cc/terms/fiducial-markers/  
OnCo record `fiducial-markers` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Tiny gold seeds or electromagnetic beacons placed in or near a tumour so the treatment machine can see exactly where it is each day.

## Summary

Soft-tissue tumours in the prostate, liver, pancreas and lung are hard to see on the X-ray images used for daily setup. Fiducial markers implanted under ultrasound or endoscopic guidance show up clearly and let the couch be shifted to the tumour's true position; electromagnetic transponders report position continuously during the beam. Fiducials make stereotactic treatment of moving targets possible and are being joined by markerless tracking on MRI and with AI.

## Fields

- Kind: Term
- Last checked: 2026-09-16
- Tags: radiation-wave1

## Sources

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

## Connected records

- cancers: [Hepatocellular carcinoma](https://onco.cc/cancers/hcc/), [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- technologies: [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/), [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/)

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JSON: https://onco.cc/api/v1/entities/fiducial-markers.json