# Modernised cobalt-60 machines as a deliberate bridge where linacs cannot be kept running

Source: https://onco.cc/ideas/idea-acc-modern-cobalt-bridge/  
OnCo record `idea-acc-modern-cobalt-bridge` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

In places where sophisticated machines break down, a modern version of the older cobalt radiotherapy unit, upgraded with image guidance, could treat more people reliably while infrastructure catches up.

## Summary

Cobalt-60 teletherapy units are mechanically simple, tolerate power instability, and need far less maintenance than linacs, but were abandoned in rich countries because of inferior beam characteristics and source-security concerns. A modernised unit with a multileaf collimator and cone-beam image guidance, with secure source logistics through the IAEA, might deliver adequate conformal treatment for common indications. This is controversial and must be tested rather than assumed.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: For cervical, breast, and palliative indications, plans from a modernised cobalt unit will meet contemporary dose-constraint standards in at least 90% of cases, and unit uptime will exceed 95% in settings where linac uptime is under 70%.
- Rationale: Appropriate technology beats the best technology if the best is switched off. The dosimetric gap between cobalt and 6 MV photons is modest for many pelvic and breast targets, and the maintenance gap is large.
- Proposed test: A planning study comparing cobalt-MLC and linac plans on 200 anonymised LMIC treatment scans against agreed constraints, followed by a two-site operational pilot measuring uptime and treatment completion.
- Maturity: speculative
- Actor: engineering

## Sources

- Bottleneck evidence (Most of the world has almost no cancer care): WHO fact sheet, Cancer: https://www.who.int/news-room/fact-sheets/detail/cancer

## Connected records

- cancers: [Cervical cancer](https://onco.cc/cancers/cervical/)
- fronts: [Radiation Therapy](https://onco.cc/fronts/radiation/)
- bottlenecks: [Most of the world has almost no cancer care](https://onco.cc/bottlenecks/b-global-access/), [Surgery and radiotherapy cure most, get least](https://onco.cc/bottlenecks/b-surgery-radiation-innovation/)

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