What is the approximate difference in intensity of exposure between the two edges of a 14*17 film as a result of the so-called "heel effect"?

The heel effect refers to the phenomenon where the intensity of radiation is greater on the side of the X-ray tube that is closest to the radiation source, while the intensity diminishes on the opposite side. This effect occurs due to the geometry of the X-ray tube and the inherent absorption characteristics of the tube's materials.

In the case of a 14x17 film, the difference in radiation exposure can be significant, with studies and practical applications indicating that the intensity difference can be around 30% between the thicker and thinner edges of the film. This means that the side of the film closest to the tube receives a higher radiation dose than the side furthest away.

This understanding is critical for radiographers when positioning patients and X-ray film to ensure that the area of interest receives adequate exposure. If not accounted for, the heel effect can lead to inconsistencies in image quality, especially in images requiring precise diagnostic clarity. Thus, recognizing that the approximate difference in exposure intensity due to the heel effect can reach around 30% is essential in radiographic practices.