Strontium-iodide (SrI2(Eu2$+))$ scintillator detector crystals in dual energy x-ray absorptiometry (DEXA) for bone densitometry imaging.

Dual-energy x-ray absorptiometry (DEXA) is a biomedical imaging tool designed to measure soft tissue and bone mineral in patients. The system is comprised of an x-ray source used to radiate over the area of interest, and a scintillator detector that measures the attenuated ray path in the patient at two different energy magnitudes. The low-dose x-rays facilitate the measurement of body composition: one mainly absorbed by bone, and the other by soft tissue. Scintillators are crystals that exhibit luminescence when struck by incoming light, and as a result can be used as radiation sensors in DEXA imaging systems. While there exists a myriad of crystals for use as scintillators, europium-doped strontium-iodide (SrI2(Eu2$+))$ are one of the most promising, low-cost, high-resolution ($\Delta $E$=$ 3.0 {\%}), high light-yield (120,000 photons/MeV), and high effective atomic number (Z$=$ 48) materials. SrI2(Eu2$+)$ is coupled with a pixelated silicon photomultiplier (SiPM) array photosensor, that which generates an electrical signal proportional to the magnitude of the incoming attenuated radiation. A 2D-array can resolve the signals spatially and generate a ``pixel representation'' image of the reference anatomy observed. A limited pixel array system can be used to generate an image of a complex mixture bone sample to prove the concept of operation, and warrant large-scale implementation with multi-pixel detectors for human-scale bone densitometry scanning.