Which of the following is not a typical feature of CT dose optimization?

• A. Lower mA
• B. Automatic exposure control
• C. Limiting scan length
• D. Increasing the radiation field to capture more anatomy

Answer: (D)

In CT dose optimization, the goal is to minimize patient exposure while preserving diagnostic image quality. Lowering the tube current reduces the radiation delivered, and automatic exposure control adjusts the current in real-time based on the body part and patient size to avoid unnecessary dose. Limiting scan length confines exposure to only the area of clinical interest, which directly lowers the total dose.

Increasing the radiation field to capture more anatomy would expose more tissue and raise the overall dose. This goes against the aim of optimization, since expanding coverage generally increases dose unless there's a specific diagnostic reason to do so. So, expanding the field is not a typical feature of CT dose optimization.