管电压对射线数字成像检测成像质量的影响

Influence of X-ray voltage on image quality of digital radiography

射线数字成像(DDA+CR)检测中,X射线管电压是最重要的工艺参数之一。目前,考虑到管电压过高会降低射线检测的主因对比度,国内外相关标准均对射线数字成像检测管电压的选用给出了相应的推荐值。试验对比DDA和CR检测时,缺陷试板在不同管电压下的数字图像质量和缺陷识别度,分析产生差别的原因,提出在合理范围内选用高于推荐值的管电压,配合相应的图像处理技术,可以提高数字图像信噪比,补偿由于管电压提高引起的图像对比灵敏度损失,最终提高缺陷识别度。试验结果表明:基于传统胶片照相工艺经验而来的管电压推荐值并不适用于射线数字成像检测,需根据特定的检测系统开展相关工艺试验确定X射线管电压上限值,且此上限值远高于相关标准的推荐值。

X-ray voltage is one of the most important process parameters in digital radiography(DDA+CR).At present,domestic and foreign standards have given corresponding recommended values for the selection of the voltage during digital radiography,mainly considering that the higher tube voltage will reduce the primary contrast of the radiation detection.Comparison was made for the image quality and rate of defect recognition on changing Xray voltage in DDA and CR,and then the reasons of the differences were analyzed.It was proposed that a higher Xray voltage within reasonable limits and corresponding image processing technology could improve the signal-tonoise ratio of the digital image,and this would compensate for image sensitivity loss due to voltage increase,and ultimately improve the rate of defect recognition.The recommended value of the tube voltage based on the experience of the traditional film photographic process is not suitable for digital radiography.It is necessary to carry out relevant tests according to the specific detection system to determine the upper limit of the X-ray tube voltage,and the upper limit is much higher than recommended value by relevant standard.