Advanced controls for X-ray units: do they really help?

摘要

Generally, X-ray equipment comprises three parts: the tube (or tubehead), the generator and the control circuit. There have been technological inputs into all three of these components to a varying degree in the century that has gone by since the discovery of X-rays. The simplest self-rectified units were called the 'tank-type' units where the step-up transformer was housed in the tube-head itself, thereby eliminating the need for heavy, high-voltage cables. These diode-type tubes did not need forced cooling either; hence the units were essentially portable. In a significant development, the half-wave output was changed to nearly constant output in the new 'Constant Potential' or CP units. The main advantage of this type was that it delivered a higher dose rate. Provision of a dual focus, metal-ceramic tube and beryllium windows were other incremental changes in the tube. Another important advancement on the tube side, so far, has been the advent of microfocal tube design.