A comparison study of dosimetry response of nano-crystalline hydroxyapatite via the EPR technique: Effect of fabrication process

•Dosimetry using HAP is important due to its similarity with bones and teeth.•Particle size, carbon impurity, and fabrication method are important in the EPR.•EPR signal intensities of the two samples are much higher than bone and alanine.•One sample can be used for calibration of bone powder in EPR retrospective dosimetry.•Synthesized HAP samples can be used in the range up to 10 kGy. In this experimental work, the EPR signal intensity of hydroxyapatite (HAP) samples were studied from a dosimetric standpoint. HAP samples have been prepared in a variety of ways for this purpose. Under the 60Co-source radiation, the synthesized samples were irradiated at various absorbed doses ranging from 0.1 to 45 kGy. The EPR signal intensity of the HAP samples in air was tested at room temperature. The peak-to-peak signal amplitude was then obtained from the difference in the EPR signal intensities. All samples show a linear EPR signal intensity with dose up to ∼10 kGy, so can be used as passive dosimeters in this range. The findings present the role of fabrication procedure and subsequently particle size, carbon impurity and morphology in determining the EPR signal intensity. Among the synthesized samples, the sample with a grain size of approximately 30 nm and a carbon impurity of 0.47 % exhibited the maximum EPR signal intensity with dose.