Which of the following are the two main types of x-ray tubes used in radiography?

The two main types of x-ray tubes used in radiography are stationary and rotating anode tubes. Stationary anode tubes consist of a fixed target where the electron beam is directed, producing x-rays at a specified point. This type of tube is typically used for lower power applications and is simpler in design. On the other hand, rotating anode tubes employ a spinning disk made of tungsten that allows for a larger surface area to be used for x-ray production. This rotation helps dissipate the heat generated during the process and increases the tube's efficiency and exposure capabilities, making it more suitable for higher voltage and power applications.

Choosing stationary and rotating anode tubes encompasses the fundamental designs critical for various applications in medical imaging. The other options focus on different characteristics or configurations that do not represent the primary classifications of x-ray tube types in radiography. For instance, linear and circular anode tubes are not standard classifications, and fixed versus movable configurations do not accurately represent the crucial differences that impact performance and application in imaging. High contrast and low contrast tubes refer to the quality of the images produced rather than the design of the tubes themselves. This distinction is essential in understanding how x-ray tubes function in practical radiographic settings.