Single atom imaging

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For an ageing population, medical imaging is increasingly important in diagnosing serious conditions such as cancer. Two important techniques make heavy reliance on radioactive tracers introduced into the body. These are positron emission tomography (PET) and single-photon emission computed tomography (SPECT). The former relates to the introduction of beta-decaying isotopes like F-18 into the body which are selectively taken up by specific organs and cancers. In the decay of this isotope, two gamma rays are emitted near back to back. The location of the source is then established from the interception of a very large ensemble of these tracks. We have come up with a new concept for medical imaging, building on the PET imaging concept, but which has the potential to locate a single radioactive atom. This is because the isotope suggested, Tc-92, decays by successive time-ordered gamma rays. We can determine the direction of these emitted gamma rays and hence determine the point of emission. This is very different to standard PET imaging as we locate one atom and not a very large ensemble via a statistical approach. This could offer unprecedented sensitivity and/or ability to use very low doses of radioactive tracer with strong benefits to the patient. This new technique could also have important applications to industrial flow processes. We intend to carry out a feasibility study by performing simulations. This will specify the best geometry for a novel scanner and determine the sensitivity achievable.