In recent years,the problem of population aging in China has been continuously intensifying.The mechanism of aging and its prevention and treatment have gradually become research hotspots.The successful establishment of aging animal models is an important part of aging-related research,and behavioral experiments can effectively evaluate these models.This article reviews the methods of constructing aging animal models from different aspects,analyzes the advantages and disadvantages of various behavioral evaluation experiments and their comparisons,with the aim of providing theoretical references for aging-related research.

In recent years,the problem of population aging in China has been continuously intensifying.The mechanism of aging and its prevention and treatment have gradually become research hotspots.The successful establishment of aging animal models is an important part of aging-related research,and behavioral experiments can effectively evaluate these models.This article reviews the methods of constructing aging animal models from different aspects,analyzes the advantages and disadvantages of various behavioral evaluation experiments and their comparisons,with the aim of providing theoretical references for aging-related research.

Objective To study the relationship between the selection of tube tension in digitalchest radiograph and image quality.Methods When tube current was fixed at 4 mAs, the choice of X-ray tube voltage changed from 60 to 120 kV.CDRAD2.0 contrast details phantom and normal human chest were exposed by X-ray system with 7 kinds of tube voltage (the difference between tube voltage was 10 kV) ,and the X-ray incidental dose of phantom surface was measured.Five radiologists with 3 years working experience evaluated the image quality on monitor and calculated the image quality factor (IQF) and image reading score.Statistics analysis was then performed by using ANOVA test and t test.According to the results, the optimum tube voltage range was determined.Results (1) The incidental dose of phantom surface increased with the higher tube voltage.(2)When the tube voltage was changed from 60 kV to 120 kV, the IQF value observed in CDRAD2.0 phantom image on monitor was 75.0±10.4,57.1±6.4,52.7±2.5,47.9±4.5, 46.0±3.8,46.0±2.8,45.2±3.5 ,there was significant statistical differences between groups(F=19.10, P<0.01).(3)The integrated score of the chest image quality in the tube voltage 90 kV and 120 kV were 12.4±0.9 and 13.0±0.7, respectively, and there was no statistical difference between two groups(t= 1.500,P>0.05).Conclusions (1)With the increase of tube tension,the display capacity of display device gradually strengthened.When the tube tension exceeded 90 kV, the increase of image quality on monitor was not evident.(2) With proper radiation dose, the value of tube tension in digital X-ray chest photograph was about 90 kV.

Objective To explore the relationship between image quality and different exposure intensity of digital radiography(DR).Methods Using a contrast-detail phantom Cdrad 2.0,observers evaluated images on the monitots when exposure parameters were 90 kV and mAs ranged from 0.5 to 16.0 mAs.Then calculate image quality figure(IQF),and ANOVA was used to analyze the difference of IQF under different radiation dose in 8 subjects.Results (1)When exposure parameters were 90 kV and mAs altered from 0.5 to 8.0 mAs.the IQF observed on the monitor was reduced,and the minimal value was 38.54±2.82.When mAs changing from 8.0 to 16.0 mAs.IQF observed on the monitor was increased,and the maximum was 44.33±2.35.(2)Under the different exposure condition,the difference of IQF values were statistically significant(F=60.35,P＜0.01).Conclusions With the increased exposure intensity,the image quality on monitor increased.When mAs was 8.0 mAs,image quality was the optimum When mAs was more than 8.0 mAs,the image quality on monitor reduced.

This paper introduces the digital stopwatch designed by our lab for teaching and experiment of medical imaging specialty.Its design idea,principle and configuration are discussed in detail.

The Koch's triangle of 110 human hearts (adults 70, children 40) has been dissected. The morphology, relationship and landmark of the atrioventricular node were observed and measured. Muscle bundles from the interatrial septum and coronary sinus orifice above and below are connected with the node. In the children the tendon of Todaro is usually tendinous, but in the adults, its posterior part is usually muscular. Deep in the triangle, there is a pyramidal space bounded by the left and right atrial walls and the top of the interventricular septum, in which there are vessels and nerves leading to the atrioventricular nodal area. According to their construction, the Koch's triangle is divided into five parts. The functional and surgical significance of these structures has been discussed.