DANB Radiation Health and Safety (RHS) Practice Exam

Which factor must be altered to maintain optimum film density when the tungsten target film distance is increased?

1. exposure time

2. developing time

3. fixing time

4. none of the above

The correct answer is: exposure time

To maintain optimum film density when the tungsten target film distance is increased, it is necessary to alter the exposure time. Increasing the distance between the tungsten target and the film results in a decrease in the intensity of the x-ray beam that reaches the film due to the inverse square law, which states that the intensity of radiation is inversely proportional to the square of the distance from the source. To compensate for this reduction in intensity, the exposure time must be increased to ensure that enough radiation reaches the film to produce a diagnostic image with the desired density. Adjusting the developing or fixing time would not address the primary issue of reduced exposure from an increased distance; these processes occur after the film has been exposed and do not affect the initial density recorded on the film during exposure. Therefore, altering the exposure time is the correct response to maintain optimum film density.