High-sensitivity fiber-optic X-ray detectors employing gadolinium oxysulfide composites

Radiation detection technologies have been applied in broad fields such as security inspection, medical diagnosis, environment monitoring and scientific analysis. Fiber-optic radiation detectors exhibit unique advantages including miniaturization, resistance to water, remote monitoring, and distributable detection. However, the low sensitivity and the high limit-of-detection limit its practical applications. Herein we demonstrated high-performance fiber-optic X-ray detectors with scintillating composites consisting of UV glue and uniformly distributed gadolinium oxysulfide (GADOX) powders. The impacts of the length, thickness and GADOX weight ratio of the composite coating upon the detector performance, were systematically investigated in terms of the generation and the coupling efficiency of radio-luminescence. Besides the high-performance scintillator, the scattering loss and the geometric factor greatly affected the detector performance. A higher sensitivity and lower limit-of-detection could be achieved by increasing the GADOX weight ratio and decreasing the thickness simultaneously. The optimal detector with the highest GADOX weight ratio (70%), exhibited a linear sensitivity to the X-ray dose rate within 31-1575 µGy_air/s, and a low limit-of-detection of ∼0.26 µGy_air/s at a tube voltage of 120 kV. The mechanism discussed here will provide insightful guidance for further development of fiber-optic radiation detectors and these promising results demonstrate the potential applications of fiber-optic detectors.