RADIATION DETECTION TECHNOLOGIES, INC. — Department of Health and Human Services SBIR Phase II: NIBIB

Description

1 The high spatial-resolution and energy-resolution of cadmium zinc telluride (CZT) and cadmium telluride2 (CdTe), compared to that of scintillators, offers superior image quality in Nuclear medicine and X-ray3 imaging applications, i.e. SPECT, PET, CT, Bone Densitometry, Oncology, Dental imaging, Airport4 security, etc. CZT and CdTe remain the desired choice for room-temperature radiation detection, but it is5 limited by high-cost and availability resulting from low yield and long production times associated with6 commercial growth techniques, i.e. the Traveling Heater Method (THM). However, the application of the7 Accelerated Crucible Rotation Technique (ACRT) growth method developed at WSU has proven to8 produce industrial quality, high-performance CdTe/CZT. This recently developed growth method not only9 allows CdTe/CZT to be grown with the same quality as material grown by THM, but also at growth rates 10 approximately 10-20 times faster than THM. Specifically, CdTe/CZT is grown by THM at a rate of 11 approximately 1-3 mm per day, whereas CdTe/CZT growth by ACRT can be accomplished at much faster 12 rates of approximately 1-3 mm per hour. THM-grown CdTe/CZT requires a lower growth temperature for 13 high-quality devices, which results in highly off-stoichiometric melts, thereby inducing the need for 14 postprocessing. These major challenges associated with the crystal growth of CdTe/CZT have been 15 overcome using ACRT. It is proposed here to further develop the ACRT growth process by introducing 16 crystal seeding in the ACRT system for CdTe and scale this process to commercial-grade levels while 17 continuing to improve the CdTe device properties for high-flux SPECT/CT applications. Chlorine doping 18 will be further explored and optimized to achieve high resistivity and high mobility-lifetime CdTe devices. 19 Numerous CdTe:Cl ingots will be grown, and devices will be produced from these ingots (cross strip and 20 commercial pixel patterns). Devices will be sent to commercial partners and customers for validation in 21 effort to integrate into commercial imaging systems. A prototype SPECT/CT system will be designed, built, 22 and images will be collected. The medical/diagnostic imaging market is projected to cross $55.7 billion by 23 2025. Stakeholders in the medical imaging market need CdTe/CZT devices now. The fruition of this project 24 will be a significant reduction (rt3x) of industrial-grade material costs by increasing the yield, reducing the 25 growth time, and eliminating post-growth anneal treatments currently used by industry. With the fast- 26 production time and high-performance of the CdTe/CZT produced in this effort, (1) the medical imaging 27 market will finally have a fast turnaround time and consistent high-performance material that can easily be 28 obtained, (2) a rt3x price reduction is projected for CdTe/CZT, and (3) Stakeholders will have access to an 29 affordable, high-performance CdTe/CZT material that can be obtained for imaging instrumentation and 30 other radiation detection applications.