Which technique change would most directly reduce patient dose without sacrificing image quality?

• A. Increase exposure time
• B. Decrease field size via collimation
• C. Increase mA
• D. Decrease kVp while maintaining density

Answer: (B)

Limiting the beam to only the area of interest directly reduces the amount of tissue that is irradiated, which lowers the patient’s radiation dose. Collimation achieves this by narrowing the field, and it also reduces scatter reaching the detector. Less scatter improves image contrast, so image quality isn’t sacrificed and can even improve with proper collimation.

Increasing exposure time or increasing the current (mA) would raise the dose. Lowering peak voltage while keeping density would typically require compensating increases in exposure (mA or time) to maintain receptor exposure, which would also raise dose. Therefore, tightening the field with collimation is the most direct way to cut patient dose without hurting image quality.