Cherenkov Light: The Invisible Glow That Makes Radiation Visible

Radiation is invisible. During treatment, clinicians rely on the treatment plan, imaging, and machine parameters to ensure radiation is being delivered as intended, but they cannot actually see the radiation beam itself.

BeamSite changes that.

BeamSite uses a natural phenomenon called Cherenkov light to provide a real-time visual representation of radiation as it is delivered. While the light is far too faint for the human eye to detect, BeamSite's specialized cameras capture it and display it instantly, giving the treatment team a new layer of visual information during radiation delivery.

So, what is Cherenkov light?

A helpful way to think about Cherenkov light is the sonic boom of light.

When an airplane travels faster than the speed of sound, it creates a sonic boom. Similarly, when high-energy radiation passes through tissue, it causes charged particles (primarily electrons) to move faster than light can travel through that tissue. This produces an extremely faint flash of blue light known as Cherenkov light.

This light is generated naturally during radiation therapy, but it is approximately 1,000 times dimmer than normal room lighting, making it impossible to see with the naked eye.

How does BeamSite capture something so faint?

BeamSite cameras are designed specifically to detect this nearly invisible light.

BeamSite is synced with the linear accelerator, capturing images only during the brief moments when the radiation beam is actually on. By ignoring ambient room light between treatment pulses, BeamSite dramatically improves the signal-to-noise ratio, allowing the faint Cherenkov emission to stand out.

BeamSite makes the invisible,visible.

Seeing radiation during treatment provides information that conventional treatment systems cannot.

By visualizing Cherenkov light in real time, clinicians can confirm where radiation is being delivered, identify unexpected radiation outside the intended treatment area, verify positioning and treatment techniques, and document what occurred during each fraction. Rather than replacing existing quality assurance tools, BeamSite complements them by adding direct visual feedback during treatment delivery.

For the first time, clinicians can see the radiation beam.