Oxygen plays an important role in life on earth. The air that we breathe provides cells with the oxygen required for energy production. This need for oxygen increases for cells that rapidly multiply such as those associated with cancer; however, the supply is limited. As a tumour increases in size not all parts will be located near to vessels carrying oxygen rich blood. This results in a reduction in the oxygen levels in cells located furthest away from the blood vessel. It has been shown that these cells with low levels of oxygen (termed hypoxic) are more resistant to damage from radiation than those that are well oxygenated. This is also known to be the case for irradiation with protons. In proton therapy, a beam of protons is fired at the tumour in order to destroy the DNA in the cancerous cells, thus killing the tumour. The amount of energy and number of protons required to achieve this is determined by the tumour volume. Currently in proton therapy the tumour is irradiated such that the whole tumour volume receives the same dose (energy deposited per unit mass). If, however, parts of the irradiated tumour are more resistant to the radiation than others this technique of delivering a uniform dose across the tumour volume is not optimal. The research planned in this project aims to address this through the use of computer modelling and imaging to produce a method of increasing the dose to those low-oxygen radiation-resistant parts of the tumour whilst delivering an appropriately lower dose to the well oxygenated regions. This advancement will improve proton beam therapy and benefit any patient undergoing this form of cancer treatment. The benefits will include increased chance of survival and fewer side effects associated with the treatment