【摘要】 目的:研究一种有效面积为1cm×1cm的半导体探测器对钼靶X射线的响应情况、探测器的输出与胶片达到质控密度时所需曝光量的函数关系,以期将此探测器实际应用于高频乳腺X线摄影AEC控制系统中。方法:将探测器置于暗盒下部,焦片距63cm,利用高频乳腺X线机分别在28kV和35kV管电压情况下对不同厚度组体模照射,测量探测器输出,分析探测器对经体模衰减后的软X射线响应情况;对不同厚度组体模阶梯状排列以不同摄影条件拍摄胶片、测量各阶梯对应密度值,分析在胶片密度为1.0和1.25时,体模厚度与所需曝光量的函数关系,再进一步分析设定密度时探测器输出值与所需曝光量的函数关系。结果:探测器输出与体模厚度之间符合V=V0e-cx函数关系;设定胶片密度时,探测器输出值与所需曝光量之间符合J=J0(V0)k/cV-k/c函数关系。结论:进行相应的电路和控制程序设计,可将此探测器应用于实际的高频乳腺X线摄影自动曝光控制系统中,实现管电压和mAs的自动控制。更多还原

【Abstract】 Objective:The response characteristic of semiconductor with effective area 1 cm × 1 cm to soft X ray was studied;and the function relation between the output of detector and necessary mAs with optimal film density was discussed in order to use this kind of semiconductor in mammography AEC.Method:The detector was placed under the cassette when the distance is 63 cm.The phantoms of different thickness were imaged when tube volt is set as 28 kV and 35 kV.The output were measured and the response characteristic were analyzed.And then the phantom of different thickness were placed in ladder shape and imaged.The density was calculated and the relationship between the phantom thickness and necessary mAs with film density 1.0 and 1.25.At last the the functon between output of detector and necessary mAs was determined.Result:The relationship between output of detector and thickness of phantom meet the function V = V0e-cx.When the film density was determined,the output of detector and mAs meet the function J = J0(V0)k/cV-k/c.Conclusion:After the design of circuit and programming,this detector can be used in mammography AEC in order to attain the AEC tube volt and mAs.更多还原