Tissue oxygenation has a significant impact upon the effectiveness of radiotherapy, with radiation-induced reactive oxygen species the dominant mediator of tissue damage. The ability to quantify the tissue partial pressure of oxygen (pO2) in tumours could thus be of great benefit for treatment planning and monitoring. Unfortunately, current methods for measuring tissue oxygen have limitations, either relying on invasive needle-type oxygen electrodes or, for non-invasive approaches, restricted by the limited penetration depth of excitation light.

A research team headed up at Dartmouth (Hanover NH) [including engineering professor Brian Pogue] is developing a new method for quantitative imaging of tissue pO2 during external-beam radiotherapy (EBRT). The technique – called Cerenkov excited phosphorescence oxygen (CEPhOx) imaging – is based on phosphorescence lifetime imaging of oxygen-sensitive probes (Phys. Med. Biol. 59 5317).