The X-ray source has a pointed tubular extension down which the beam is directed. The exit point of the extension is fitted with a lead bead which is used to direct the beam onto the centre of the film as well as enabling the operator to accurately focus the beam for different subject distances and settings. The system dispenses with markings on the equipment and is simple and efficient to use. The lead bead is small in size so that it does not blank out significant areas of the X-ray photograph, but it is sufficiently large for its shadow to be seen without difficulty.
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