To enable rapid radionuclide identification in nuclear emergency scenarios, we propose a lightweight residual convolutional neural network (CNN) tailored for portable γ-ray spectrometers. A high-fidelity Geant4 model of a LaBr3:Ce detector is constructed, and γ-ray energy spectra are simulated for six single nuclides (22Na, 60Co, 133Ba, 137Cs, 152Eu, 226Ra), which are further extended to dual- and triple-nuclide mixtures to match typical nuclear emergency conditions. One-dimensional spectra are reshaped into 64 × 64 matrices through serpentine mapping and then fed into a lightweight residual CNN with an embedded channel attention mechanism to enhance the extraction of key spectral features. The proposed model achieves perfect performance for single-nuclide identification (Precision = Recall = F1 = 100.00

Accurate neutron dose assessment in humans is critical for radiation protection and nuclear emergency medical rescue. This study aims to establish a reliable method for evaluating neutron doses using a newly developed voxel physical phantom and to determine the lower detection limit of neutron absorbed dose via 24 Na activity measurement. A voxel physical phantom, based on the ICRP 110 male adult reference computational phantom, was constructed using tissue-equivalent materials and sodium carbonate solutions to simulate sodium content in various organs. The phantom was irradiated with 252 Cf neutrons, and the induced 24 Na activity was measured using a 3-inch NaI(Tl) detector. Monte Carlo simulations were employed to validate the neutron fluence and dose distribution within the phantom. The results showed that the whole-body neutron absorbed dose in the voxel physical phantom differed by less than 3.1% compared with the ICRP 110 male adult reference computational phantom, with induced 24 Na activity deviations of less than 3.0% for the whole body and 20.0% for major tissues and organs. When using a 3-inch NaI(Tl) detector to evaluate the neutron absorbed dose of the ICRP 110 male adult reference computational phantom irradiated with 252 Cf neutrons instantaneously by measuring the induced 24 Na activity, the lower limit of neutron absorbed dose detection was ≤ 31 mGy. This demonstrates the accuracy of neutron dose assessment using computational phantoms, providing a practical and cost-effective alternative to conventional approaches.

Hexavalent chromium (Cr(VI)) is a widely present carcinogenic environmental pollutant, has demonstrated well-documented neurotoxic and enterotoxic effects in aquatic organisms, yet limited research exists on mitigating its toxicity through brain-gut-microbiota axis regulation. Vitamin C (VC), a potent antioxidant and immunomodulator, has shown potential in mitigating heavy metal toxicity. Nevertheless, how VC regulates Cr(VI) toxicity via the brain-gut-microbiota axis remains unclear. To investigate VC’s potential protective role, adult zebrafish were divided into three groups: control, 2 mg/L Cr(VI), 2 mg/L Cr(VI) + 2 mg/L VC groups, with a 60-day exposure period. Histopathological changes, 16S rRNA, intestinal, and brain RNA-sequencing were examined. The results showed that VC modulated neuropathological lesions and intestinal goblet cell vacuolization caused by Cr(VI). 16S rRNA further confirmed VC partially modulated microbiota homeostasis. Transcriptomic analysis identified 78 differentially expressed genes (DEGs) in the brain; KEGG enrichment analysis showed these DEGs are associated with neurological function and gastrointestinal carcinogenesis pathways. Concurrently, 52 DEGs in intestinal were linked to viral infection and neural signaling pathways. Correlation analyses demonstrated pathogenic Aeromonas was positively correlated with ace, enpep, prss1, asah2, and cd36 in the brain, those are downregulated DEGs, whereas beneficial Pseudomonas was positively correlated with c6ast4 and nfe211b in intestinal, they are upregulated DEGs. This indicates Aeromonas and Pseudomonas could act as key mediators through which VC reduces Cr(VI)-induced neuro- and immunotoxicity. Collectively, these findings provide mechanistic insights into VC’s protective role against parallel disruptions along the microbiota-gut-brain axis, suggesting its potential as a waterborne supplement for reducing Cr(VI) toxicity in aquaculture system. • VC modulated Cr(VI) induced brain and intestinal histopathological damage • VC partial modulated Cr(VI) induced microbial homeostasis • VC modulated Cr(VI)-induced neurotoxicity by transcriptomic analysis • VC modulated Cr(VI)-induced enterotoxicity by transcriptomic analysis • Microbial community shifts are correlated with gene expression patterns

Neutron dose assessment in radiation accidents relies on measuring induced 2 ⁴Na activity via the 23 Na(n, γ ) 2 ⁴Na reaction. However, the effect of body size on neutron moderation, gamma self-absorption, and organ distribution—remains poorly quantified, with conflicting literature reports. To systematically evaluate the body size effect on neutron absorbed dose and 2 ⁴Na yield, four human voxel phantoms of different body sizes (5-, 10-, 15-, and 38 year-old individuals) were irradiated in MCNP simulations with 2 ⁵ 2 Cf and 28 monoenergetic neutron sources (10 −9 –20 MeV) under six geometries. The neutron absorbed dose, induced 2 ⁴Na activity per unit mass, and the conversion coefficients between 24 Na activity per unit mass and neutron absorbed dose were calculated. The results show that body size significantly affects the neutron dose. When the human body is irradiated with 2 ⁵ 2 Cf neutrons under different irradiation geometries, the conversion coefficients between 2 ⁴Na activity per unit mass and neutron absorbed dose are at least 48.3% larger in adults than in 5 year-old children. When the human body is irradiated with monoenergetic neutrons under isotropic irradiation geometry, these conversion coefficients decrease with increasing body size for neutron energies <0.1 MeV, and increase with increasing body size for neutron energies >0.1 MeV. For 10 −9 MeV neutron irradiation, the coefficient for adults is 26.5% smaller than that of 5 year-old children. Conversely, for 20 MeV neutron irradiation, the coefficient for adults is 114.2% larger than that for 5 year-old children.

The analysis of thermoluminescence (TL) glow curve is an important way to investigate the trap structure of the materials as well as the kinetics of the charge carrier transfer. Most currently used methods rely on the existence of an explicit expression of the theoretical glow curve. However, since the set of kinetic equations describing the TL process does not have analytical solutions, the derivation of an explicit expression always involves some sort of assumptions and approximations, which can compromise the universality and accuracy of the method. This paper proposes a new algorithm that focuses on the original kinetic equations and does not necessitate an explicit expression to analyze the TL glow curve. This algorithm establishes an objective function to evaluate the fitness of a selected combination of kinetic parameters, and then using the genetic algorithm (GA) to search for the optimal parameters. Various occasions were numerically simulated, demonstrating the algorithm's capability to handle kinetics of different order, multiple interactive peaks, deep trap, non-linear heating, and temperature dependent parameter cases. An actual glow curve of the LiF:Mg,Cu,P chip was also analyzed using this algorithm, and the corresponding kinetic parameters were identified. This algorithm provides a more universal and valid method for TL glow curve analysis.

The in-vivo electron paramagnetic resonance (EPR) method can be used for on-site, rapid, and non-invasive detection of radiation dose to casualties after nuclear and radiation emergencies. For in-vivo EPR spectrum analysis, manual labeling of peaks and calculation of signal intensity are often used, which have problems such as large workload and interference by subjective factors. In this study, a method for automatic classification and identification of in-vivo EPR spectra was established using support vector machine (SVM) technology, which can in-batch and automatically identify and screen out invalid spectra due to vibration and dental surface water interference during in-vivo EPR measurements. In this study, a spectrum analysis method based on genetic algorithm optimization neural network (GA-BPNN) was established, which can automatically identify the radiation-induced signals in in-vivo EPR spectra and predict the radiation doses received by the injured. The experimental results showed that the SVM and GA-BPNN spectrum processing methods established in this study could effectively accomplish the automatic spectra classification and radiation dose prediction, and could meet the needs of dose assessment in nuclear emergency. This study explored the application of machine learning methods in EPR spectrum processing, improved the intelligence level of EPR spectrum processing, and would help to enhance the efficiency of mass EPR spectra processing.

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.

目的 解决LiF:Mg,Cu,P热释光剂量计20～50 keV区域能量响应过高问题,改善热释光剂量计的能量响应,提高其测量精度.方法 通过在热释光片前设置补偿滤片,减少20～50 keV X/γ射线在热释光片的能量沉积,降低该能量区域的能量响应.结合实验测量现有BIRM?1000型LiF:Mg,Cu,P热释光剂量计性能参数,使用蒙特卡罗方法模拟计算改进后的热释光剂量计能量响应.结果 在热释光片前加装厚度0.6 mm带孔304不锈钢片,光片后加装厚度10 mm金属铍片,可降低热释光剂量计在20～50 keV区域能量响应,此时的热释光剂量计的探测阈值≤1.31×10?4 mGy,方向性差异<7％.结论 在热释光片前加装0.6 mm带孔304不锈钢片,可有效改善LiF:Mg,Cu,P热释光剂量计能量响应曲线,提高其测量精度.

The dose caused by external exposure to neutrons can be evaluated by measuring the induced 24Na activity due to interaction of 23Na in human body with neutrons. To investigate the difference between male and female in the 24Na activity, the MCNP code is used to simulate the ICRP 110 adult male and female reference computa-tional phantoms irradiated by 252Cf neutrons. The results show that the average absorbed dose of whole body caused by per unit neutron fluence for the female phantom is (5.22 +/- 0.06)% -(6.84 +/- 0.05)% higher than that for the male phantom. The 24Na specific activity of male tissues/organs is higher than that of female, except muscle tissues, bone, colon, kidney, red marrow, spleen, gallbladder, rectum and gonads. The highest intensity of 24Na characteristic gamma rays on the body surface occurred at Z = 125 cm on the back for the male phantom, while the highest gamma ray fluence for the female phantom is at Z = 116 cm, both of which are aligned with liver. When 1 Gy of 252Cf neutrons irradiate the ICRP110 phantoms, (1.51-2.44) x 105 and (3.70-5.97) x 104 24Na characteristic gamma rays can be recorded in 10 min by 3-inch NaI(Tl) detector and cb 5 x 3 cm3 HPGe detector, respectively.

The neutron dose resulting from external irradiation can be evaluated by measuring the counts of characteristicγrays produced by24Na in the human body. The detection geometry with the highest detection efficiency for measuring the whole-body24Na activity has not been studied. In this work, the MCNP code is used to calculate the spatial distribution of24Na in the human body irradiated by neutrons with different energies in different irradiation geometries. The fluence distribution of24Na characteristicγrays on the body surface is calculated. The counts of24Na characteristicγrays induced by monochromatic neutron irradiation are simulated to fit the scenarios of neutron irradiation by a continuous energy spectrum neutron. When the spontaneous neutrons from252Cf with 1Gy dose irradiate the human body, (3.63-4.35) × 1010 24Na atoms are produced. The lower detection limit for the neutron absorption dose is reduced from ∼100 to less than 1 mGy when the radiation detector is placed over the back of the human body close to the liver. The relative error between the measured counts of24Na characteristic γ rays caused by252Cf neutron irradiation and the counts fitted by monochromatic neutron irradiation data is less than 5.7%. The neutron dose received from a continuous energy spectrum neutron can be acquired quickly and accurately by weighted summing of the data for monochromatic neutron irradiations calculated in this paper, which is more convenient and practical than the previous method.

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.

The nuclides inhaled during nuclear accidents usually cause internal contamination of the lungs with low activity. Although a parallel-hole imaging system, which is widely used in medical gamma cameras, has a high resolution and good image quality, owing to its extremely low detection efficiency, it remains difficult to obtain images of inhaled lung contamination. In this study, the Monte Carlo method was used to study the internal lung contamination imaging using the MPA-MURA coded-aperture collimator. The imaging system consisted of an adult male lung model, with a mosaicked, pattern-centered, and anti-symmetric MURA coded-aperture collimator model and a CsI (Tl) detector model. The MLEM decoding algorithm was used to reconstruct the internal contamination image, and the complementary imaging method was used to reduce the number of artifacts. The full width at half maximum of the I-131 point source image reconstructed by the MPA-MURA coded-aperture imaging reached 2.51 mm, and the signal-to-noise ratio of the simplified respiratory tract source (I-131) image reconstructed through MPA-MURA coded-aperture imaging was 3.98 dB. Although the spatial resolution of MPA-MURA coded-aperture imaging is not as good as that of parallel-hole imaging, the detection efficiency of PMA-MURA coded-aperture imaging is two orders of magnitude higher than that of parallel-hole collimator imaging. Considering the low activity level of internal lung contamination caused by nuclear accidents, PMA-MURA coded-aperture imaging has significant potential for the development of lung contamination imaging.

Real-time measurement of temperature in living cells exposed to microwaves is challenging because of the low spatial resolution of conventional temperature probes. Here, we established a noninvasive method by using a temperature-dependent fluorescent dye, Rhodamine B (Rho-B) to stain living cells that were exposed to a customized microwave exposure device. The relationship between Rho-B fluorescence and the temperature of living cells, and between Fluo4/AM and the inward inflow of Ca2+ were established. The results showed that the fluorescence intensity changed by 7.9%/degrees C as the temperature rose from 25 degrees C to 37 degrees C. The spatial resolution and temporal resolution of this method were 225 x 225 mu m 2 and 1.5 s, respectively. In conclusion, the real-time temperature measurement technique is simple to use and requires no specialized equipment beyond a LSCM. This method can provide real-time information of the temperature changes in cells simultaneously with the investigation of calcium concentration.

获得外照射条件下的大鼠器官剂量,对于放射医学剂量-效应关系研究具有重要意义.本文基于大鼠微型CT图像建立大鼠体素模型,并研究光子外照射情况下大鼠器官剂量.大鼠体素模型质量323.7 g,单个体素尺寸为0.16 mm×0.16 mm×2 mm,包含大鼠大部分关键器官和组织.利用蒙特卡罗模拟程序MCNP计算获得了4种照射几何条件、21个单能(10 keV～10 MeV)平行光子束外照射情况下的器官剂量转换系数,最后对器官剂量随光子能量的变化进行了分析与讨论.

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.

The development of new dosimeters with good dosimetric properties is important for quality control in radiation applications. A new practical electron spin resonance (ESR) dosimeter based on carbonated hydroxyapatite that simulated the composition and structure of tooth enamel was specially synthesized. The synthesized material was investigated by transmission electron microscope, X-ray diffraction, fourier transform infrared spectroscopy and X-ray photo electron spectroscopy to confirm to the main composition of carbonated hydroxyapatite with CO32- successfully doped into the crystal lattice through optimizing the synthesis process of C/P molar ratio, pH value dynamical adjustment, annealing temperature and time. The dosimetric properties were systematically investigated by ESR spectroscopy. The results indicated that the radiation induced signal had a good dose response within a relatively wide dose range. The dose response was linear in the dose range of 0-400 Gy with a correlation coefficient of 0.9999 and had dose accumulative effect in the experimental dose range of 0-100 Gy. In a wider dose range up to 30 kGy, the dose response also presented linear feature in double-logarithmic coordinate system with a correlation coefficient of 0.9970. The dose detection limit was about 0.34Gy with a given probability of 95% confidence level depending upon a rigid calculation algorithm. The signal was extremely stable in the observation time of 360 days with a variation coefficient of 3.8%. The radiation sensitivity of the material showed no remarkable variation against photon energy from 662 KeV to 1.25 MeV and dose rate from 0.86 Gy/min to 12.17 Gy/min. The material showed more sensitive in lower photon energy range below 662 keV, which hint additional calibration may need when using in special photon energy condition. The preliminary results suggested that this newly developed dosimeter was potential to become a practical dosimeter that would expand the application fields of ESR dosimetry.

PURPOSE:Intracellular electroporation occurs when the cells are exposed to nanosecond pulsed electric field (nsPEF). It is believed the electroporation (formation and extension of pores on the membrane induced by external electric field) is affected significantly by the transmembrane potential. This paper analyzed transmembrane potential induced by nsPEF in the term of pulse frequency spectrum, aiming to provide a theoretical explanation to intracellular bio-effects.METHODS:Based on the double-shelled spherical cell model, the frequency dependence of transmembrane potential was obtained by solving Laplace's equation, while the time course of transmembrane potential was obtained by a method combined with discrete Fourier transform and Laplace transform. First-order Debye equation was used to describe the dielectric relaxation of the cell medium.RESULTS:Frequency-domain analysis showed that when the electric field frequency was higher than 105 Hz, the transmembrane potential on the organelle membrane (ΔΦo) was increasing to exceed the transmembrane potential on the cellular membrane (ΔΦc). In the time-domain analysis, transmembrane potentials induced by four nsPEF (short trapezoid, long trapezoid, bipolar and sine shapes) with the same field strength were compared with each other. It showed that ΔΦo is obviously larger than ΔΦc if the curve of the normalized frequency spectrum of the pulse is more similar with the curve of normalized ΔΦo in frequency domain. Pulses with major frequency components higher than 108 Hz lead to both small ΔΦo and ΔΦc. This may explain why high power pulsed microwave lead to unobvious bio-effects of cells than nsPEF with trapezoid form.CONCLUSION:Through the pulse frequency spectrum it is clearer to understand the relationship between nsPEF and the transmembrane potential.

Nasal swab analysis is an effective method to provide valuable information for early and fast estimates of alpha radionuclide intakes and resultant doses. In this study, an inhalation environment was built by use of lead nitrate aerosol to simulate alpha radioactive aerosol inhalation. The result of exposure and swabbing experiments with guinea pigs shows that the lead smeared on nasal swabs represents ∼13 % of intake if samples are acquired within 90 min after exposure and declines over time with a half-time of 1.4 h. The results also indicate a decreasing swabbing efficiency with post-exposure time. This study could provide useful information for the method of nasal swab used in nuclear and radiological emergencies.

We developed a high-performance ELISA assay and measured serum BHMT levels in healthy individuals and patients with acute liver injury (ALI). The detection range of this ELISA assay was from 1.56 to 100 ng/ml. BHMT levels are significantly higher in ALI groups. In the healthy group (n = 244), the median value (interquartile range, IQR 0-56.40) was 1.83 ng/ml. In the ALI group (n = 42), the median value of BHMT was 748.48 ng/ml (IQR, 0-51095.92). ROC curve analysis demonstrated good sensitivity (0.86) and specificity (0.98). In addition, in five ALI cases with time course samples available, BHMT and ALT both followed the "rise and fall'' temporal pattern with the disease progression. However, the slopes of BHMT curves were steeper than ALT curves. And in three out of the five cases, BHMT levels peaked 1 day earlier than ALT levels be a sensitive marker with good prognostic value.

The power absorbed by the human brain has possible implications in the study of the central nervous system-related biological effects of electromagnetic fields. In order to determine the specific absorption rate (SAR) of radio frequency (RF) waves in the human brain, and to investigate the effects of geometry and polarisation on SAR value, the finite-difference time-domain method was applied for the SAR computation. An anatomically realistic model scaled to a height of 1.70 m and a mass of 63 kg was selected, which included 14 million voxels segmented into 39 tissue types. The results suggested that high SAR values were found in the brain, i.e. ∼250 MHz for vertical polarisation and 900-1200 MHz both for vertical and horizontal polarisation, which may be the result of head resonance at these frequencies.