CAMRT Radiography Practice Exam

What method helps reduce patient dose during a CT without changing technical factors?

1. Lowering kV

2. Increasing pitch

3. Using a larger field of view

4. Reducing scan time

The correct answer is: Increasing pitch

Increasing pitch in a CT scan allows for a faster scan time relative to the table movement, which means the irradiated volume is covered more quickly. Higher pitch results in a decreased radiation dose for the patient because the system can produce images while exposing the patient for a shorter period. This is beneficial as it does not require any changes to technical factors like the kV or mAs, thus optimizing patient safety while maintaining image quality. In contrast, lowering kV can affect image quality and contrast by reducing the energy of the x-rays produced, which might be counterproductive depending on the type of scan. Using a larger field of view might not necessarily reduce dose effectively, as it could lead to more tissue being irradiated. Reducing scan time can potentially increase pixel noise in the resulting images, which may require higher radiation to maintain quality. Hence, increasing pitch is a favored method for dose reduction without compromising technical parameters significantly.