Lu-Free Scintillators for PET

DESCRIPTION provided by applicant Positron Emission Tomography PET is a functional imaging technique with the potential to quantify the rates of biological processes in vivo PET imaging can provide diagnosis for symptoms of diseases such as cancer Alzheimerandapos s disease head trauma and stroke However to allow exploitation of the full potential of PET there is urgent need for both improvement in the performance of PET systems and reduction in their cost Both of these factors are strongly influenced by the available detector technology Scintillation crystals are currently used as detectors in PET Requirements for the scintillation crystals used in PET include fast response high sensitivity high light output high energy and timing resolution and low cost At present most PET systems use crystals of Lu SiO Ce LSO or its derivative LYSO which satisfy most of the requirements listed above Nevertheless issues remain with the cost and availability of lutetium that must be considered with respect to the future production of scintillators for PET and when developing potential new scintillators There are several diverse factors that influence the cost and availability of the lutetium oxide material used in LSO LYSO crystal growth for PET but perhaps the most fundamental is geological The main mineral sources for lutetium are xenotime LuPO and ion adsorption clays both of which are predominately found in China There is very little production of lutetium from any other country It is difficult to make long term predictions of Chinaandapos s strategy with respect to rare earth exports but recent years have seen ever increasing production controls and higher tariffs on exported rare earth materials in general On the other hand gadolinium also an attractive rare earth element for scintillators can be found in several different minerals including monazite which exist in various parts of the world thus making itandapos s availability less dependent on the economy and politics of a single nation Gadolinium offers some additional advantages compared to lutetium Its natural abundance in the earthandapos s crust is an order of magnitude greater than lutetium and its larger ionic size makes it considerably easier to separate and purify relative to the smaller rare earth ions such as lutetium These two fundamental factors combine to offer the potential of significantly lower cost for the same level of purity by a factor of The larger ionic size also means that it provides a substitutional site for cerium that is better matched to the relatively large size of the cerium ion Finally unlke lutetium gadolinium has no natural radioactivity an additional benefit In view of the serious concerns about availability and cost of Lu the goal of the proposed project is to investigate novel Lu free scintillators for PET imaging The idea is to achieve reduction in cost maintain a predictable supply of raw materials and exceed the performance of LSO In view of the advantages cited above we plan to design the new scintillator based on Gd as the rare earth ion and incorporating it into a cubic garnet matrix PUBLIC HEALTH RELEVANCE The proposed research will investigate a promising detector technology which will have a major impact in health care particularly in the development of low cost and high performance detectors for in vivo medical imaging Other areas to which this research will be of benefit are physics research materials studies oil exploration homeland defense and non destructive testing