Answer to Question #3575 Submitted to "Ask the Experts"

When x rays or photons pass through the body, either they are absorbed, scattered, or pass through the body unaffected. If scattered x rays or photons reach the x-ray film, they fog the film, which decreases the quality of the image and provides no useful information in the picture. A grid is a device containing lead strips that is placed between the patient and the x-ray film to absorb scattered x-ray photons before they reach the x-ray film. A Bucky is a device that moves the grid while the x ray is being taken. The motion keeps the lead strips from being seen on the x-ray picture. Since the thickness and density of the head is the same no matter what the position of the patient, standing or lying on the table does not make any difference in the amount of x-ray exposure required to make a good-quality x-ray picture of the head.

Radiation in high doses to the lens of the eye can cause the formation of cataracts, which is the clouding of the lens of the eye. However, it would require roughly 1,000 x rays of the skull in order to reach the level of radiation dose that could cause cataracts.

Kenneth L. Miller, CHP, CMHP

Editor's Note: A grid and Bucky device are usually found in all table- and wall-mounted x-ray film holders. To see the effect of the Bucky-moving grid, hold your hand in front of your face at about one foot or 30 cm, and spread your fingers. Look at an object in the distance while holding your hand still and while shaking your hand.