Proton beam therapy for eye tumours

Dr Andrzej Kacperek making adjustments to the proton beam equipment used for the treatment of tumours within the eye at the Clatterbridge Centre for Oncology, Wirral, UK. The semi-rigid masks (white) worn by patients during the treatment are made especially to fit each specific patient as the beam of low-energy protons has to be accurately targeted to avoid damage to healthy eye tissue. The mask, together with a mouthpiece, clamps the patient's head in the correct alignment for the best treatment. The protons are emitted from the brass collimator at centre right, which is precisely machined to the profile of a specific patient's tumour, and the dose is calculated to damage the DNA (deoxyribonucleic acid) of the tumour. Cancerous cells, because of their high rate of division and their reduced ability to repair damaged DNA, are particularly vulnerable to this attack., by JAMES KING-HOLMES/SCIENCE PHOTO LIBRARY