This chapter summarizes the more important practical aspects of dental X-ray generating equipment. There are several different units available from various manufacturers. They vary in appearance, complexity and cost, but all conventional units consist of three main components:

These dental units can either be fixed (wall, floor or ceiling mounted) or mobile (attached to a sturdy frame on wheels) as shown in Figs 3.1A and B. A recent development has been the production of hand-held dental units, as shown in Fig. 3.1C, particularly useful for domiciliary and forensic radiology.

Main components of the tubehead

A diagram of a typical tubehead is shown in Fig. 3.2. The main components include:

• The glass X-ray tube, including the filament, copper block and the target (see Ch. 2)

• The step-up transformer required to step-up the mains voltage of 240 volts to the high voltage (kV) required across the X-ray tube

• The step-down transformer required to step-down the mains voltage of 240 volts to the low voltage current required to heat the filament

• A surrounding lead shield to minimize leakage

• Surrounding oil to facilitate heat removal

• Aluminium filtration to remove harmful low-energy (soft) X-rays (see Fig. 3.3)

• The collimator – a metal disc or cylinder with central aperture designed to shape and limit the beam size to a rectangle (the same size as intraoral film) or round with a maximum diameter of 6 cm (see Figs 3.3 and 3.4)

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Related

Related posts:

1. 19: Introduction to radiological interpretation
2. 12: Oblique lateral radiography
3. 23: Implant assessment
4. 26: Differential diagnosis of radiolucent lesions of the jaws
5. 22: The periodontal tissues and periodontal disease
6. 31: The maxillary antra

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