A radiographer receives 400 mR/hr standing 1 foot from a C-arm fluoroscopy unit.What is the exposure rate if the radiographer moves to a distance of 3 feet?

Question

Quizplus · Accepted Answer

According to the inverse square law, the exposure rate decreases as the distance from the source increases. The equation for this law is I1/I2 = (D2/D1)^2, where I1 is the initial exposure rate (400 mR/hr), I2 is the exposure rate at the new distance, D1 is the initial distance (1 foot), and D2 is the new distance (3 feet). Solving for I2, we get I2 = I1 * (D1/D2)^2 = 400 * (1/3)^2 = 44.44 mR/hr, which is within the range of 25 to 50 mR/hr given in choice C. Therefore, the correct answer is C.

A Radiographer Receives 400 MR/hr Standing 1 Foot from a C-Arm