Poly(N-isopropylacrylamide) Microgel-Based Sensor for Clinical-Level X-ray Dose Measurements

Hydrogel sensors that can accurately determine X-ray doses are crucial in the clinic. In this article, we reported radiofluorogenic poly(N-isopropylacrylamide) (pNIPAm)-based microgels for X-ray dose measurements. PNIPAm-based microgels were injected with two fluorescent moieties: hydroxyphenyl fluorescein, which is a radiofluorogenic molecule, and CdSe quantum dots, which were relatively unaffected by X-ray irradiation. Using single-wavelength excitation, our microgels showed a linear change in ratiometric fluorescent signals as a function of increasing the X-ray dose from 0 to 15 Gy. Furthermore, our microgel sensors had good temperature stability (25 to 65 degrees C) and postirradiation stability within 4 days. Importantly, we harnessed our sensors to determine X-ray doses in soft tissues and B16-F10 cells, to monitor absorbed doses by eye lenses using dedicated accessories for radiation safety glasses, and to verify intestine doses in the 3D-printed abdominal phantom under different radiation energies (160 keV, 225 keV, and 6 MV)/dose rates (1.225, 4, and 4.487 Gy/min). In each case, the doses determined by our sensors are comparable to the results of commercial ionization chambers, thermoluminescent dosimeters, and clinical treatment planning systems. Therefore, we believe our microgel sensors provide a method for clinical-level X-ray dose measurements.