CAMRT Radiography Practice Exam

What is the primary cause of what is referred to as a "gassy" x-ray tube?

1. Disconnected filament

2. Filament vaporization

3. Overheating of the rotor

4. Excessive kVp settings

The correct answer is: Filament vaporization

The primary cause of a "gassy" x-ray tube is filament vaporization. This phenomenon occurs when the filament in the x-ray tube heats up to a point where the material starts to evaporate and deposits itself on the glass envelope of the tube. As the filament continues to vaporize, it can create a gas layer inside the tube, which can lead to a reduction in the efficiency of x-ray production and could potentially cause tube failure. In the context of the other choices, while a disconnected filament would prevent the tube from functioning at all, it does not lead to the accumulation of gas. Overheating of the rotor may result in mechanical failure but does not contribute to a "gassy" condition. Similarly, excessive kilovolt peak (kVp) settings might lead to different issues like image quality concerns or tube damage but are not directly related to the production of gas within the tube. Thus, filament vaporization is the primary concern when discussing the “gassy” state of an x-ray tube.