Y. Wang

At present most radiation dose meters have serious problems on aspects of energy response and angular response. In order to improve the accuracy of dose measurements, a method of average angular response has been proposed. The method can not only correct the energy response, but also the angular response. This method has been verified on NaI(Tl)(50 mm× 50 mm) scintillation detectors, but has not been proved on other types and sizes of detectors, In this paper the method is also verified for LaBr3(Ce) scintillation detectors and HPGe detector To apply the method, first of all, five detectors are simulated by Geant4 and average angular response values are calculated. Then experiments are performed to get the count rates of full energy peak by standard point source of 137Cs, 60Co and 152Eu. After that the dose values of five detectors are calculated with the method of average angular response. Finally experimental results are got. These results are divided into two groups to analyze the impact of detectors of various types and sizes. The result of the first group shows that the method is appropriate for different types of detector to measure dose, with deviations of less than 5% compared with theoretical values. Moreover, when the detector's energy resolution is better and the count rate of the full energy peak is calculated more precisely, the measured dose can be obtained more precisely. At the same time, the result of the second group illustrates that the method is also suited for different sizes of detectors, with deviations of less than 8% compared with theoretical values.

INTRODUCTION: Mild cognitive impairment (MCI) is a transitional stage to dementia, with cerebral small vessel disease (SVD) as a key contributor. Since retinal microvascular changes may mirror cerebral pathology, we investigated the associations between retinal microvasculature, neuroimaging, and plasma biomarkers in individuals with MCI. METHODS: 61 MCI patients and 57 controls (CU) underwent retinal imaging, Neuroimaging (peak width of skeletonized diffusivity [PSMD], white matter hyperintensities [WMH]), plasma biomarker analysis, and cognitive assessment. Partial correlations and mediation analyses were adjusted for confounders. RESULTS: MCI exhibited greater retinal tortuosity (p < 0.05) and sparser vasculature (p < 0.001), correlating with higher PSMD, WMH volumes, and adverse plasma biomarkers (all p < 0.05). Mediation analysis revealed PSMD and WMH volumes partially mediated retinal-cognitive associations (p for all mediation < 0.05). DISCUSSION: Retinal microvascular dysfunction in MCI reflects concurrent cerebral SVD and neurodegeneration, supporting its potential as a non-invasive biomarker for early cognitive decline.