Question

For a given distance for coverage, which of the following is TRUE?

1) as reconstruction FOV increases, patient dose increases
2) as pitch increases, patient dose decreases
3) as slice thickness increases, patient dose decreases

Answer 1

In CT imaging, an increased FOV does not affect patient dose, higher pitch results in decreased patient dose, and increased slice thickness can lead to a decreased patient dose.

Step-by-step explanation:

The question deals with the factors affecting patient dose in computed tomography (CT) imaging, and the relationships between field of view (FOV), pitch, and slice thickness when a certain distance of coverage is needed. First, it is not true that as the reconstruction FOV increases, the patient dose increases; the patient dose is primarily affected by the amount of radiation used during the scan, not the FOV.

Second, as the pitch increases, the patient dose typically decreases, because pitch is defined as the table movement per rotation divided by the beam width. A higher pitch means the table moves faster, and thus, the patient is exposed to radiation for a shorter duration. Lastly, as the slice thickness increases, the patient dose can also decrease since a thicker slice can be obtained with a single rotation of the x-ray source, meaning less overall radiation is needed to cover the same volume.