CAMRT Radiography Practice Exam

What is the effect on image quality as the pitch of the CT scan increases?

1. Image quality improves

2. Image quality remains unchanged

3. Image quality decreases

4. Image quality depends on the type of tissue scanned

The correct answer is: Image quality decreases

As the pitch of a CT scan increases, the image quality generally decreases. This is primarily due to the way pitch affects the amount of data collected during the scan. Pitch is defined as the table movement per rotation of the x-ray tube divided by the total width of the x-ray beam. When the pitch increases, it indicates that the table is moving faster relative to the width of the beam. Higher pitch values lead to more gaps between adjacent slices of data, resulting in less overlap and fewer data points for image reconstruction. This can cause a loss of detail and may create artifacts in the images, leading to a reduction in diagnostic accuracy. Consequently, the lower effective resolution and increased chances for motion artifacts contribute to the overall decrease in image quality when the pitch is higher. In certain cases, such as high-speed imaging or specific diagnostic requirements, a higher pitch can be beneficial; however, for general image quality assessment, an increase in pitch is linked to a decline in clarity and detail. This is particularly important in diagnostic imaging where maintaining high image quality is crucial for accurate interpretations.