磷屏成像的计量性能测试及其在大面积平面源均匀性评价中的应用

针对磷屏成像技术在放射性活度计量领域的应用需求,开展了磷屏成像响应的重复性、一致性、时间线性与活度线性研究。结果表明:成像灰度值重复性为8.6%(k=2),190mm×200mm的磷屏成像区域对于点状源的响应一致;磷屏成像的灰度值与照射的时间成正比,相同照射时间所产生的灰度值与源的发射率也成正比。以这些计量性能结果为基础,严格按照ISO 8769∶2010的均匀性评价规则对150mm×100mm的大面积源进行了均匀性测量,建立了定量和直观表达平面源均匀性的方法,从而为改善平面源的制备工艺,建立符合国际标准的大面积源计量器具提供了参考评估方法。

Metrology Performance Test of Phosphor Screen Imaging and Its Application on Uniformity Evaluating of Large-Area Sources

According to the application requirement of the phosphor screen imaging technology in the field of radioactivity measurement,tests of the repeatability,consistency and linearity with time and radioactivity involving the imaging of phosphor screen are carried out under laboratory conditions.The results show that the repeatability of imaging gray value is 8.6％ (k=2),the response of a phosphor screen imaging to point source in the sensitive area of 190 mm×200 mm is equivalent,the gray value of imaging phosphor screen becomes proportional with the exposure time,and the gray value created by the equal exposure time is proportional to the emission rate of the source.Based on these performance as well as strictly respecting to the uniformity evaluation rules of ISO 8769 ∶ 2010,the uniformity measurement to a large area source of 150 mm× 100 mm is executed,the quantitative and intuitive expression method to the uniformity of a plane source is established,so as to develop a reference method of improving the preparation process to pIane source in accordance with the ISO 8769 ∶ 2010 international standard.