CAMRT Radiography Practice Exam

What is the purpose of the Exposure Maintenance formula mAs1 / mAs2 = D1^2 / D2^2?

1. To calculate radiation dose

2. To maintain receptor exposure

3. To determine film type

4. To enhance image quality

The correct answer is: To maintain receptor exposure

The purpose of the Exposure Maintenance formula, represented as mAs1 / mAs2 = D1^2 / D2^2, is primarily to maintain receptor exposure during radiographic imaging. This formula allows radiographers to adjust the milliampere-seconds (mAs) when there are changes in the distance between the radiation source and the image receptor. When the distance (D) changes, the intensity of radiation reaching the image receptor also changes according to the inverse square law. Thus, if the distance increases, the amount of radiation reaching the receptor decreases and vice versa. The formula provides a method to calculate the necessary adjustment in mAs to ensure that the receptor receives a consistent level of exposure, which is vital for producing high-quality images without overexposing or underexposing the film or digital receptor. Maintaining proper receptor exposure is crucial for generating diagnostic images while reducing the patient's exposure to unnecessary radiation. Other options like calculating radiation dose or determining film type do not directly relate to this specific formula’s purpose in adjusting exposure based on distance. Similarly, while enhancing image quality can be an end result of proper exposure levels, it is not the primary focus of the exposure maintenance formula itself.