Towards improved, cost-effective medical imaging
Positron emission tomography (PET) is a medical imaging tool for acquiring structural and functional images of the body in a non-invasive manner. It works by detecting the positron emission decay of a radioisotope injected in the body and converting it into light through scintillators. PET scanners use large numbers of crystalline materials as scintillators, making PET a rather expensive method. As a result, research into new inexpensive materials is necessary for PET to be more broadly used. Furthermore, radiation dose is a major concern necessitating high detection efficiency of the scintillation layer. The EU-funded ‘Structured scintillators for medical imaging’ (String) project aimed to increase the performance and decrease the cost of PET scanners by developing ceramic scintillators. Project partners looked into materials with emission times less than 20 ns which, however, emit light in the UV range thus making them unsuitable for the photon detectors used. To overcome this limitation, researchers used organic wavelength shifters coupled to interference filters to prevent the undesirable UV light from reaching the photo detectors The String project also proposed a novel stacking structure consisting of a ceramic scintillator with a wavelength shifter between two interference filters. This stack showed a slightly reduced light output and thus project partners concentrated their efforts on modelling the emission signal as a function of the decay time of the scintillator. PET is an important method for accurately diagnosing cancer and neurological conditions such as Alzheimer’s disease. Application of cost-effective scintillator materials will reduce the price of PET machines and enhance the level of medical diagnostics at reduced costs.