Doctors at Massachusetts General Hospital (MGH) are pioneering an exciting new approach to proton therapy. This short film introduces the pencil-beam scanner, a way of firing protons at tumours with impressive precision. The pencil beam allows more precise shaping of the beam's range, as doctors can adjust the beam throughout the duration of the therapy as if they were painting the tumour.

If you enjoyed this video, then you may want to watch this film about the history of the MGH and its approach to cancer therapy.