Human skeletal dosimetry has experienced great developments in radiation protection in recent years by using the heterogeneous skeletal model. While for the rats experimentally used in radiation medicine, the investigation on skeletal dosimetry were mainly based on the homogeneous skeletal model, leading to inaccurate assessments of dose to radiosensitive tissues of red bone marrow (RBM) and bone surface. The purpose of this study is to develop a rat model with heterogeneous skeletal system and to investigate the dose difference in bone tissues for external photon irradiation. The high resolution of microCT images of a rat weighing 335 g were segmented into bone cortical, bone trabecular, bone marrow as well as other organs to construct the rat model. The absorbed dose to bone cortical, bone trabecular and bone marrow were calculated respectively by using Monte Carlo simulation for 22 external monoenergetic photon beams between 10 keV and 10 MeV under four different irradiation geometries conditions (left lateral [LL], right lateral [RL], dorsal-ventral [DV], ventral-dorsal [VD]). The calculated absorbed dose data were expressed as dose conversion coefficients and presented in this article, and the effect of irradiation conditions, photon energies and bone tissues density on the skeletal dose was discussed. The results showed that the dose conversion coefficients varying the photon energy for bone cortical, bone trabecular and bone marrow exhibit different trends and have the same sensitivity to irradiation conditions. The dose difference in bone tissues indicated that bone cortical and bone trabecular have significant attenuation effect on the energy deposition in bone marrow and bone surface for photon energies below 0.2 MeV. The set of dose conversion coefficients in this work can be used to determine the absorbed dose to skeletal system for external photon irradiation and to supplement the rat skeletal dosimetry.

Appropriate training of the related personnel is one of the most important aspects in nuclear and radiological emergency preparedness and response. The use of simulation training could provide the trainees learning experience of a lifelike, hands-on scenario without associated radiation safety restrictions. In this study, we established a radiation field simulation system that includes two separate parts. For small-area radiation field simulation, a set of simulation sources and detectors was designed based on ultra wide band distance measurement technology. For large-area field simulation, a Gaussian plume model was used to simulate the dispersion of released radioactive aerosols and calculate the consequent radiation field. Also, a Global Position System positioning and wireless transmission technique was used for simulation instruments' data acquisition. This system could create a verisimilar but also safe and radiation-free environment and can be used in the training of nuclear emergency first responders, rescue teams or radiation protection personnel.

In case of a nuclear or radiological emergency, there may be a very large population of individuals being affected by radiation exposure. Rapid and on-site examinations of possible internal radioactive contaminations are required for early dose assessment and large-scale screening. With the appropriate methodology, early dose information of internal exposure can be instantly obtained by a handheld spectrometer only. In this study, we extended the use of a handheld LaBr3 spectrometer to rough internal dose assessment. A family of real source BOMAB phantoms was applied for efficiency calibration of different detecting geometries. Detecting limits of several nuclides of major concern was also investigated. The result of this study can be used for initial dose assessment and medical triage during the first response of nuclear and radiological emergencies.

When responding to nuclear and radiological emergencies, rapid and on-site detections of possible internal radioactive contaminants are required for early dose estimation and medical triage. Nasal swab analysis is an effective method to provide valuable information for early and fast estimates of alpha radionuclide inhalation intakes and resultant doses. In this study, to improve the quality of nasal swab measurements, a specialised double-detector alpha counter was designed. Various parameters including swab materials, sample pre-preparation, angle-dependence and vacuum dependence were investigated to optimise the reliability and convenience of the nasal swab method. An improved procedure of direct nasal swab measurement was eventually established, which could be used to obtain early data for initial dose assessment during the first response of nuclear and radiological emergencies.