Is the CT beam well collimated?

• A. Yes
• B. No
• C. Sometimes
• D. Depends on model

Answer: (A)

Collimation shapes the x-ray beam to a defined width that matches the detector array, setting the slice thickness and helping keep exposure within the target region. In CT, pre-patient collimators trim the beam so only the intended portion of the anatomy is irradiated, which reduces scatter and dose and supports consistent, high-quality image data as the tube rotates. Modern scanners also use beam-shaping filters, like bow-tie filters, to further balance intensity across the field, but the essential point is that the beam is kept tightly controlled to the imaging region. Because of these design features, the CT beam is well collimated in typical practice, making “Yes” the best answer.