Main Parts of an X-Ray Machine and How They Work Together

The X-ray tube

The tube is a vacuum glass or metal envelope containing a cathode filament and an anode. Heating the filament releases electrons, and a high voltage between cathode and anode accelerates them onto the anode, where a small fraction of the energy becomes X-rays and the rest becomes heat. Most diagnostic tubes use a rotating anode so the heat is spread over a ring rather than a single spot.

The size of the focal spot affects sharpness, and the tube heat capacity limits how many exposures can be made in a row. The tube sits in a housing with oil, shielding and a window, and is the part most subject to wear.

Generator and control console

The generator converts mains power to the high voltage (kV) and tube current (mA) set by the operator, and controls exposure time. Modern high-frequency generators produce a stable output and have power ratings expressed in kW; the topic is discussed further in X-ray generator power.

The console is where the radiographer selects the technique or anatomical programme. In Villa's Moviplan iC bucky room, an 8 inch touchscreen controls SID, tube angle and collimation and integrates the generator settings, and movements of the floating table are released by a photocell system instead of footswitches.

Automatic exposure control (AEC) uses measuring chambers or the detector signal to end the exposure when the right level is reached, and when properly calibrated it reduces retakes.

Collimator and beam shaping

The collimator sits below the tube and uses movable lead shutters to limit the beam to the area of interest, with a light field showing the position. Collimation reduces both the dose to the patient and the scatter reaching the receptor, and a good collimator also holds added filters that remove low-energy photons.

Automatic collimation, which follows the detector size, and virtual collimation on the screen are available on many modern systems. Collimation errors are among the most common reasons for poor technique.

Grid, detector, table and tube support

The anti-scatter grid is a set of thin lead strips that absorbs scattered radiation before it reaches the receptor. It improves contrast but requires more exposure, so it may be removed for small patients. See our article on the anti-scatter grid and bucky for details. The image receptor, now usually a flat-panel detector, converts the X-ray pattern into the image; the technologies are described in flat panel detector types.

The table or wall stand holds the patient and the bucky, and the tube support, whether a floor column or a ceiling tubestand, positions the tube relative to them. In mobile units these parts are combined on a motorised cart with a battery.

Safety, interlocks and common faults

Safety features include exposure switches that require continuous pressure, door interlocks and warning lights where installed, emergency stops, cable strain reliefs and tube thermal protection. Regular quality assurance checks the output, collimator alignment and image quality.

It helps to follow the signal path when teaching: the console sets the parameters, the generator supplies the tube, the collimator shapes the beam, the detector records and the workstation processes. When an image is poor, search along this chain, starting with the simplest causes such as positioning and collimation.

Typical faults relate to the tube and its cables, the high-voltage connectors, collimator lamps and the detector. Preventive maintenance reduces unplanned downtime. For help with a specification or service plan, contact Beckfinity.