Radiologic Technology Supervisor and Operator Practice Exam

Exposure rate from an X-ray source follows the inverse square relationship: it is proportional to 1 over the distance squared. If you double the distance, the exposure rate becomes (1/(2d)^2) = 1/4 of the original. So the exposure rate is reduced to one quarter of its initial value. In practice, increasing distance greatly reduces exposure at a point, and to maintain the same receptor exposure you would need to increase tube current or exposure time accordingly.