Tungsten alloy is more and more widely used for radiation protection to shield people or objects from radiation. For example, it is promising in applications of converging collimator - an important part of human brain SPECT, which is known to increase the photon detection efficiency compared to conventional parallel-hole collimator in SPECT imaging. That is because tungsten alloy is poison-free with better radiation shielding ability than lead (poisonous).
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It has been reported that a converging half-cone-beam collimator is especially suitable for human brain SPECT, allowing close positioning of the detector to the patient’s head, while avoiding truncation of the caudal portions of the brain. Some researchers have simulated and assessed modified half-cone-beam collimators for further gain in photon detection efficiency with the same spatial resolution. Using Monte Carlo simulation, they modeled an astigmatic half-cone-beam collimator with axial and transaxial convergence in two orthogonal focal lines. This kind of astigmatic collimation allows utilization of the whole detector field of view, thus increasing the efficiency of the collimator.
