# Brachytherapy (internal radiotherapy)

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

## TL;DR

Radiotherapy from the inside: radioactive seeds or a temporary source are placed in or next to the tumour, so the dose falls off steeply and nearby organs are spared.

## Summary

Low-dose-rate seeds (iodine-125) permanently implanted in the prostate cure low-risk disease as well as surgery; high-dose-rate brachytherapy boosts external beam in intermediate- and high-risk prostate cancer (ASCENDE-RT) and is essential for cervical cancer, where image-guided brachytherapy to ≥85 Gy EQD2 drives cure (EMBRACE). Also used for oesophageal palliation, skin, breast (partial-breast) and eye (plaque for uveal melanoma). It needs skilled operators and access has declined in some countries as external-beam options improved.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: brachytherapy boost; HDR brachytherapy; LDR brachytherapy; seed implant; interstitial brachytherapy; intracavitary

## Sources

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

## Connected records

- terms: [Gray unit (Gy)](https://onco.cc/terms/gray-unit/), [Hypofractionation (fewer, larger radiotherapy doses)](https://onco.cc/terms/hypofractionation/), [IMRT / IGRT / VMAT (modern external beam radiotherapy)](https://onco.cc/terms/imrt-term/), [Re-irradiation](https://onco.cc/terms/re-irradiation/)
- cancers: [Cervical cancer](https://onco.cc/cancers/cervical/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- fronts: [Radiation Therapy](https://onco.cc/fronts/radiation/)
- technologies: [Brachytherapy](https://onco.cc/technologies/brachytherapy/), [High-dose-rate brachytherapy](https://onco.cc/technologies/hdr-brachytherapy/), [Low-dose-rate seed brachytherapy](https://onco.cc/technologies/ldr-seed-brachytherapy/), [Remote afterloaders for HDR brachytherapy](https://onco.cc/technologies/brachytherapy-afterloaders/)
- trials: [ASCENDE-RT](https://onco.cc/trials/ascende-rt/)

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