In a world first, the new method could provide a non-invasive way to temporarily open the brain's borders to allow tumour-fighting medication to target the cancer.... The brain is shielded by a layer of specialized cells called the blood-brain barrier.... It allows needed substances like oxygen and sugar in while keeping out toxic substances. But now, scientists have been able to use an advanced ultrasound technique to non-invasively, and temporarily, open the blood-brain barrier in patients w