Question

Which of the following reduced patient dose at the expense of increasing the apparent noise in the image?

1) kVp
2) pitch
3) table increment
4) mAs

Answer 1

Reducing the milliampere-seconds (mAs) decreases patient radiation dose but increases the apparent noise in the CT image, making mAs the correct answer.

Step-by-step explanation:

In medical imaging, especially in the context of computed tomography (CT) scans, reducing the milliampere-seconds (mAs) of the X-ray source will decrease the patient radiation dose. However, this reduction in dose comes at the expense of increased apparent noise in the resulting image. The noise in an image refers to random variations in pixel intensity, which result in a grainy appearance. To counterbalance noise, sometimes other parameters such as kilovoltage peak (kVp), pitch, or table increment are adjusted. Among these parameters, mAs is directly related to the patient dose and image noise--decreasing mAs reduces the dose but increases noise, while increasing mAs does the opposite. Conversely, changes in kVp affect image contrast as well as patient dose, but not noise in the same direct way that changes in mAs do. Adjusting the pitch, which is the distance the table moves during a single rotation of the X-ray tube, or adjusting the table increment, can affect image quality and coverage speed, but do not have as direct a relationship with noise and dose as mAs does.