Dental X-ray cylinders, or tubeheads, produce X-ray beams to take radiographs.
A dental X-ray cylinder, also called an X-ray tubehead, is a tightly sealed, heavy metal housing that contains the radiograph tube used for taking X-rays of patients' teeth, according to "Torres and Ehrlich Modern Dental Assisting." The X-ray tubehead produces the beam that passes through the dental patient and reaches the dental film in his or her mouth to create an image. Dental X-rays are important because they allow the dentist to see conditions that aren't clinically visible in the patient's mouth. The X-ray tubehead is one of the primary components of a dental X-ray machine, which also features an extension arm and control panel, according to "Dental Radiography."
General Components
Inside a dental X-ray tubehead is an aluminum or leaded-glass covering called the tubehead seal that allows X-rays to exit from the tubehead. It serves as a filter to the X-ray beam. The tubehead also contains the heart of the X-ray generating system--the X-ray tube. Also in the tubehead is the transformer, a device that alters the voltage of incoming electricity, as well as aluminum disks that filter out nonpenetrating, longer wavelength X-rays. These aluminum disks are about 0.5 mm thick. In addition, a lead collimator--or lead plate with a central hole--fits directly over the opening of the metal housing where the X-rays leave. It restricts the size of the X-ray beam.
Oils
The dental X-ray tubehead additionally contains insulating oils that surround the X-ray tube and transformers inside the tubehead. These oils prevent overheating by absorbing the heat created when X-rays are produced. The oil actually absorbs about 99 percent of the X-rays generated in the X-ray tube, with the remaining 1 percent exiting the tubehead as a beam toward the dental patient.
Lead
A leaded-glass housing is part of the X-ray tube, which is a glass vacuum tube from which all air has been removed. This dental tube is about 6 inches long and 1 inch in diameter. The leaded-glass housing keeps X-rays from escaping in all directions. One part of the leaded-glass tube directs the X-ray beam toward the aluminum disks, lead collimator and another part of the tubehead called the positioning-indicating device (PID). The PID is a lead-lined cylinder that extends from the opening of the tubehead's metal body and aims/shapes the X-ray beam.
Cathode
The cathode, or negative electrode, in the X-ray tube includes a tungsten wire filament in a cup-shaped holder. The cathode basically supplies the electrons needed to generate the X-rays. The electrons produced in the cathode are accelerated toward the positive anode when a dental radiographer pushes the exposure button on the dental X-ray unit.
Anode
The anode, or positive electrode, in the X-ray tube has a wafer-thin tungsten plate embedded in a solid copper rod. The anode's responsibility is to convert the electrons from the cathode into X-ray photons. The copper rod dissipates the heat away from the tungsten plate/target, thus preventing wear on this target. At this point is when the X-rays travel through an unleaded glass window, the tubehead seal, the aluminum disks and the lead collimator before entering the tube through the PID.
Tags: X-ray tube, X-ray tubehead, aluminum disks, X-ray beam, dental X-ray, aluminum disks lead
