If the source-object distance is reduced from 16 inches to 8 inches, what must be done to compensate?

When the source-object distance is reduced, it affects the intensity of the radiation reaching the object due to the inverse square law, which states that intensity is inversely proportional to the square of the distance from the source. Reducing the distance from 16 inches to 8 inches results in a fourfold increase in intensity (since (16/8)^2 = 4).

To maintain consistent image quality and exposure to radiation, a change in technique is necessary. This can be achieved by using a different radiographic technique, such as switching from the paralleling technique to the bisecting angle technique. The bisecting angle technique allows for a closer placement of the film or sensor relative to the object being radiographed, which can help adjust for the increased intensity resulting from the decreased distance.

While increasing exposure time might seem like a compensatory action, in this scenario, it is more efficient to alter the technique to achieve optimal results with the new source-object distance. Thus, changing the method used for obtaining the radiograph is an appropriate compensation in response to the increased radiation intensity due to the proximity of the source.