CAMRT Radiography Practice Exam

When using the Inverse square law, what variable changes when the distance from a radiation source is altered?

1. Intensity of exposure

2. Type of radiation

3. Quality of the beam

4. Duration of the exposure

The correct answer is: Intensity of exposure

When applying the Inverse Square Law, the variable that changes when the distance from a radiation source is altered is the intensity of exposure. The law explains how the intensity of radiation decreases as the distance from the source increases, illustrating that the intensity is inversely proportional to the square of the distance. This means that if you double the distance from the radiation source, the intensity of exposure decreases to one-fourth of its original value. This relationship is fundamental in radiography, as it helps professionals understand how to manage radiation doses effectively based on the proximity to the source. In contrast, the type of radiation remains constant regardless of distance; it does not change regardless of how far one is from the source. Similarly, the quality of the beam, which refers to the penetrating power of the radiation, does not inherently alter with distance; it is primarily influenced by other factors such as filtration. Lastly, the duration of exposure refers to the time the patient or equipment is exposed to radiation, which is a separate consideration and does not directly correlate with the change in distance concerning the intensity of exposure.