Which statement about CT dose optimization is true?

• A. Lowering mA alone is sufficient to optimize dose.
• B. Increasing the scan length reduces dose.
• C. Limiting scan length and using dose modulation are common optimization strategies.
• D. Shielding is never used in CT.

Answer: (C)

CT dose optimization means delivering the smallest radiation dose that still yields acceptable diagnostic images. The best-supported strategies are limiting the scan length and using dose modulation. Limiting scan length reduces the volume exposed, so less radiation reaches the patient overall. Dose modulation Tailors the tube current to the anatomy as the scan progresses, providing higher current where the body attenuates more and lowering it where it attenuates less, which maintains image quality while reducing dose. Simply lowering mA without regard to image quality or anatomy can compromise diagnostic usefulness, and increasing the scan length would increase, not decrease, dose. Shielding isn’t a universal solution in CT, and relying on it alone isn’t part of standard dose optimization. So, limiting the scan length and employing dose modulation are the practical, commonly used optimization strategies.