Direct radiographic magnification: evaluation of three microfocus x-ray tubes

Three microfocus x-ray tubes (RSI, Siemens, and Eimac) were evaluated for their focal and imaging characteristics. The RSI and Siemens focal spots had similar homogeneous radiation intensity distributions. The Eimac tube had an asymmetric intensity distribution. Because of their focal spot characteristics, the RSI and Siemens tubes provided superior magnification radiographs for small objects. The Siemens and Eimac tubes were preferable for magnification of thick objects because their larger object-film air gap reduced scattered radiation reaching the film.