Thallium bromide for x- and gamma-ray detection

Thallium bromide (TlBr) is a semiconductor material with high atomic numbers (35, and 81) and density (7.6 g/cm3) that lead to high detection efficiency of x- and gamma-ray photons. As TlBr devices are operated as direct detectors, they also yield excellent energy and spatial resolutions. Moreover, the constituents of TlBr are inexpensive and its growth process is simpler compared to other high-z semiconductor materials, such as cadmium zinc telluride (CZT), which significantly lowers the overall production cost.

Two TlBr devices with approximate dimensions of 4x4x5 mm3 and electrodes pixelated with 1.7 mm pixel pitch.

We are working on the development and testing of TlBr devices in collaboration with Radiation Monitoring Devices, Inc (RMD, Watertown, MA, USA). Our aim is to study the feasibility of using TlBr detectors for energy resolved photon-counting for x-ray imaging, for gamma spectroscopic applications such as single photon emission computed tomography (SPECT), and for time-resolved gamma detection, such as TOF-PET or prompt gamma imaging (PGI) for proton range verification in proton therapy.

Together with RMD, we have developed the novel Cerenkov Charge Induction (CCI) TlBr detectors, which make use of the high transparency of TlBr to detect Cerenkov light and add TOF timing performance to the already excellent energy and spatial resolutions of TlBr. The simultaneous outstanding performance of CCI TlBr devices in timing, energy, and spatial resolution added to its high detection efficiency (greater than that of BGO) put them in a unique position to be used in TOF-PET and PGI.


Ariño-Estrada G, et al., 2019, First Cerenkov Charge Induction (CCI) TlBr Detector for TOF-PET and Proton Range Verification, Phys. Med. Biol.In press.


NIH-NCI R01 CA193994, TlBr Detectors for High Resolution PET Imaging

NIH-NIBIB R03 EB025533, Potential of Cerenkov Radiation for Fast Timing of TlBr Semiconductor Detectors for PET

UC Davis Academic Federation Innovative Developmental Award, Energy-resolved photon-counting TlBr detectors for X-ray medical imaging


Gerard Ariño-Estrada (

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