CAMRT Radiography Practice Exam

Which method can help reduce off-focus radiation?

1. Increasing the target angle

2. Using a fixed diaphragm

3. Adding more kVp

4. Using a larger focal spot

The correct answer is: Using a fixed diaphragm

Using a fixed diaphragm is an effective method for reducing off-focus radiation, as it serves to limit the primary x-ray beam to a specific area of interest. Off-focus radiation occurs when x-rays are produced outside of the desired focal spot, leading to scatter that can affect image quality and increase patient dose. A fixed diaphragm, or collimator, helps to focus the beam more precisely onto the region being examined and minimizes the amount of radiation that is scattered and contributes to unwanted exposure. By restricting the beam and reducing the area irradiated, the overall effect is a decrease in off-focus radiation, enhancing the quality of the diagnostic image and ensuring that the patient receives a lower radiation dose. While increasing the target angle, adding more kVp, or using a larger focal spot can influence factors such as beam quality and intensity, they do not specifically address the issue of off-focus radiation in the same way that a fixed diaphragm does. Therefore, the use of a fixed diaphragm remains the most direct and effective approach to mitigate off-focus radiation in radiographic imaging.