Scintillation is the process by which a material converts radiation into light. The use of scintillation in inorganic salts to detect radiation dates back over a century when it was first used in the discovery and calibration of radioactivity. Today, scintillation detectors are used in a variety of remote sensing and non-invasive applications such as medical imaging, security screening for nuclear materials, astrophysical exploration, and geophysical exploration in the pursuit of new energy reserves. At the heart of such detectors is a high-purity material that scintillates in response to ionizing radiation. The key factors for a good scintillation material include high light output (brightness), high gamma ray stopping efficiency, fast response, low cost, and minimum after glow.
High performance scintillation crystals are developed principally for OEM manufacturers of PET and PET-CT scanners. Other applications are in micro-PET detectors used in drug research and gamma cameras used for specific applications, such as breast and prostate examinations. Additional non-medical applications for scintillation-detector devices include gamma ray detector systems for homeland security, geological surveying, materials analysis, high energy physics, and nuclear stockpile monitoring. Typically up to one third of the cost of a PET machine is the cost of the crystal material and another third in the photo-detectors.
Novel scintillation crystals have provided the greatest source of performance and cost improvement for PET scanners in recent years. In addition to image quality improvements, resolution and sensitivity gains, improved crystals offer faster imaging times, allowing users to achieve more scans per day and hence increased ROI.
The scientific team at ZMS has accumulated decades of experience in the field of crystal optical materials. The company’s scientists have introduced many well-known crystals to the industry and continue on its comprehensive research program focused on laser media and scintillation materials.
ZMS has recently and successfully developed LFS, a new high-performance scintillation material specifically aimed at medical imaging systems and other industrial applications. The mass production and marketing of the LFS has been licensed to Northrop Grumman under a long term contract, and Zecotek has now initiated the development of a next-generation, green-sensitive scintillation material which, combined with next generation photo-detectors, should provide the foundation of a new generation of PET, PET-CT, and PET-MRI scanners.
To bring production of the new material to a commercial level ZMSS is setting up a research lab and crystal growth unit in its Singapore facilities. This will be equipped with dedicated Czochralski crystal pulling furnaces as well as with the necessary equipment and machinery to cut and polish the grown material.
PET (Positron Emission Tomography) is based on the detection of the gamma radiation emanating from a patient’s body when produced clinically with radioactive trace elements associated to specific metabolic functions. In practice, a patient is given a dose of an unstable isotope linked with a compound such as a sugar, and which decays during metabolism releasing a positron. The emitted positron annihilates with an electron producing a pair of photons which are detected and amplified and the resulting signal processed into an image. Because the signals are generated in areas of metabolic events PET produces images of biological and functional activity rather than images of structure, such as those produced by conventional X-ray or CT (Computed Tomography). While it is useful, for example, to diagnose the presence of a cancer, which PET can accomplish, it is vastly more useful to visually locate the cancer within the bodily structure where it resides. This simultaneous imaging of both structure and function was first made possible with the relatively recent marriage of PET and CT. The PET-CT combination has thus given considerable improvement to medical imaging diagnostics and, in the process, created a new, billion-dollar industry.
MRI (Magnetic Resonance Imaging) tomography is an anatomical imaging technology based on intense magnetic fields and used to produce images, like CT, of bodily structures. With its relatively high resolution and ability to take in vivo images, MRI offers distinct advantages over conventional CT and with improved diagnostic capabilities and patient outcomes has become an invaluable tool in the diagnosis of oncological conditions, neurological disorders, and other diseases.
While an MRI offers relatively high resolution and the ability to take in vivo images, a combined PET-MRI scanner promises a range of clinical applications otherwise inaccessible to separate systems. The key impediment to date to realizing a PET-MRI combination has been the intense magnetic environment of the MRI which precludes the use of conventional photo-multiplying tube photo detectors and which Zecotek’s MAPD photo detectors now make feasible.
Zecotek has entered a joint effort with Prof. Thomas Lewellan and the University of Washington to develop a PET/MRI solution. This collaboration combines the outstanding expertise of the University’s Imaging Research Laboratory in the design of small-animal PET devices together with Zecotek technologies; specifically, new scintillation materials and what has been described as ‘breakthrough technologies’ in the field of high-sensitivity silicon photo-detectors (MAPDs) which are, importantly, insensitive to magnetic fields. The unique combination of these technologies in a PET/MRI, with the additional features of improved performance characteristics offered by the individual components, will constitute a completely new level of medical imaging.
The system under development is being designed as either a stand-alone or for integration into any commercial MRI scanner. Our approach is to a compact and cost-competitive solution which, in addition to enabling PET inserts into conventional MRI, will open new markets for purpose-designed devices specific to mammography, brain scan, limbs, hands, feet, etc.
