Question

Which of the following is TRUE regarding the slice thickness of an image reconstructed from a helical scan

a. on a multi-row detector scanner the thickness is equal to the beam collimation
b. on a single-row detector scanner, the thickness is equal to the beam collimation
c. on a multi-row detector scanner the thickness is always equal to the detector size

Answer 1

In a helical CT scan, the slice thickness can vary for multi-row detector scanners and is not always equal to the collimation or detector size, whereas for single-row detector scanners, the slice thickness is typically equal to the beam collimation.

Step-by-step explanation:

The student's question pertains to the relationship between slice thickness in a helical CT scan and beam collimation or detector size. For multi-row detector scanners, the answer to the question is that the slice thickness can be less than, equal to, or greater than the collimation thickness and is not necessarily equal to the size of one detector row. The collimation defines the width of the x-ray beam and thus the thickness of tissue volume sampled by one rotation of the scanner. On the other hand, single-row detector scanners typically have a slice thickness equal to the beam collimation, because there is only one row of detectors.