What technical factor controls the temperature of the cathode filament within the x-ray tube?

The temperature of the cathode filament within the x-ray tube is primarily controlled by milliamperage (mA). When the filament is heated by an electrical current, it produces electrons through a process known as thermionic emission. The higher the mA setting, the more current flows through the filament, leading to a higher temperature and, consequently, a greater number of electrons being emitted. This is crucial for generating x-rays, as the quantity of electrons available influences the intensity of the resulting x-ray beam.

In contrast, voltage (kV) affects the energy of the x-rays produced rather than the temperature of the cathode filament. Exposure time (s) determines how long the x-ray tube is active and impacting the total number of x-rays produced, but does not directly influence cathode temperature. Frequency (Hz) relates to the alternating current supply and is not relevant to the temperature control of the filament. Thus, milliamperage is the key technical factor that governs the cathode filament's temperature in an x-ray tube.