# FLASH radiotherapy

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

## TL;DR

Delivering an entire dose in under a second, which in animals spares healthy tissue while still killing the tumour.

## Summary

FLASH radiotherapy delivers the entire dose in milliseconds rather than minutes, at ultra-high dose rates above 40 Gy/s, and in preclinical models this spares normal tissue while killing the tumour equally well. First-in-human trials (FAST-01/02 with protons, Varian; electron trials in Lausanne) show feasibility. The mechanism, proposed as oxygen depletion or radical recombination, is debated, and the clinical effect is unproven. If real, the effect could widen the therapeutic window dramatically, but hardware constraints make it hard to reach deep tumours with current machines. The simple version is that giving radiation in a fraction of a second may protect healthy tissue, and human trials are only now testing whether that holds.

## Fields

- Kind: Technology
- Status: phase-1
- Last checked: 2026-09-04
- Tags: frontier
- Principle: Dose delivered in milliseconds rather than minutes; differential normal-tissue sparing.
- Strengths: Potential to widen therapeutic window dramatically
- Limitations: Unproven in humans; Hardware constraints for deep tumours

## Sources

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

## Connected records

- fronts: [Radiation Therapy](https://onco.cc/fronts/radiation/)
- companies: [Empyrean Medical Systems](https://onco.cc/companies/empyrean-medical-systems/), [IntraOp Medical](https://onco.cc/companies/intraop-medical/), [THERYQ](https://onco.cc/companies/theryq/), [Varian (Siemens Healthineers)](https://onco.cc/companies/varian/)
- trials: [Flash Radiotherapy for Skin Cancer](https://onco.cc/trials/nct07455331/)
- technologies: [FLASH research accelerators (Oriatron, Mobetron FLASH, ProBeam FLASH)](https://onco.cc/technologies/flash-research-accelerators/), [Intraoperative radiotherapy (IORT)](https://onco.cc/technologies/intraoperative-radiotherapy/), [Pencil-beam scanning and intensity-modulated proton therapy](https://onco.cc/technologies/intensity-modulated-proton-therapy/), [Proton therapy machines: cyclotrons, synchrotrons and single-room systems](https://onco.cc/technologies/proton-therapy-systems/), [Radiotherapy QA phantoms and dosimeters (Sun Nuclear, IBA Dosimetry, PTW)](https://onco.cc/technologies/radiotherapy-qa-phantoms-dosimeters/), [Very-high-energy electron therapy](https://onco.cc/technologies/vhee-radiotherapy/)
- people: [Jean Bourhis](https://onco.cc/people/jean-bourhis/), [Marie-Catherine Vozenin](https://onco.cc/people/marie-catherine-vozenin/)
- bottlenecks: [Surgery and radiotherapy cure most, get least](https://onco.cc/bottlenecks/b-surgery-radiation-innovation/)
- ideas: [A coordinated FLASH radiotherapy evidence programme with shared dose-rate standards](https://onco.cc/ideas/idea-fund-flash-evidence-programme/), [A regulatory pathway for new radiotherapy techniques modelled on drug development](https://onco.cc/ideas/idea-fund-radiotherapy-innovation-pathway/), [A translation fund for academic surgical devices and radiotherapy technology](https://onco.cc/ideas/idea-fund-device-and-technique-translation-fund/), [Compact FLASH and proton systems at the price of a conventional linac](https://onco.cc/ideas/idea-moon-compact-flash-proton/), [Pick the radiation dose that switches the immune alarm on, not off](https://onco.cc/ideas/idea-bio2-radiotherapy-sting-fractionation/)
- journals: [Radiotherapy and Oncology](https://onco.cc/journals/radiotherapy-and-oncology/)
- terms: [Radiotherapy](https://onco.cc/terms/radiotherapy/)
- institutions: [American Society for Radiation Oncology](https://onco.cc/institutions/astro/), [NCT/UCC Dresden, University Hospital Carl Gustav Carus](https://onco.cc/institutions/nct-dresden/)
- roadmaps: [Radiotherapy roadmap: X-rays → shaped beams → fewer fractions, particles and FLASH](https://onco.cc/roadmaps/radiation-roadmap/)

---
JSON: https://onco.cc/api/v1/entities/flash-rt.json