Pitch (CT)
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In helical CT, pitch (P) is has two terminologies depending on whether single slice or multislice CT scanners are used 1-3.
Single slice CT (SSCT)
The term detector pitch is used and is defined as table distance traveled in one 360° gantry rotation divided by beam collimation 2.
For example, if the table travelled 50mm5mm in one rotation and the beam collimation was 5mm then pitch equals 50mm5mm / 5m5mm = 1.0.
Choice of pitch affects both image quality and patient dose 2:
- P = 1.0 - x-ray beams are contiguous for adjacent rotations
- P > 1.0 - x-ray beams are not contiguous for adjacent rotations, i.e. there are gaps in between the x-ray beams and tissue is not irradiated
- P < 1.0 - there is x-ray beam overlap; i.e. a volume of tissue is irradiated more than once per scan
Thus a pitch > 1.0 results in decreased patient dose but also decreased image quality (through less projections obtained resulting in lower SNR). A pitch of < 1.0 results in better image quality but at higher patient dose.
Multislice CT (MSCT)
Multislice CT (MSCT) - "beam pitch" is defined as table distance traveled in one 360 degree gantry rotation divided by total thickness of all simultaneously acquired slices 3.
-<p>In helical CT, <strong>pitch (P)</strong> is has two terminologies depending on whether single slice or multislice CT scanners are used <sup>1-3</sup>.</p><h5>Single slice CT (SSCT)</h5><p>The term <strong>detector pitch</strong> is used and is defined as table distance traveled in one 360° gantry rotation divided by beam collimation <sup>2</sup>.</p><p>For example, if the table travelled 50mm in one rotation and the beam collimation was 5mm then pitch equals 50mm / 5m = 1.0. </p><p>Choice of pitch affects both image quality and patient dose <sup>2</sup>:</p><ul>- +<p>In helical CT, <strong>pitch (P)</strong> is has two terminologies depending on whether single slice or multislice CT scanners are used <sup>1-3</sup>.</p><h5>Single slice CT (SSCT)</h5><p>The term <strong>detector pitch</strong> is used and is defined as table distance traveled in one 360° gantry rotation divided by beam collimation <sup>2</sup>.</p><p>For example, if the table travelled 5mm in one rotation and the beam collimation was 5mm then pitch equals 5mm / 5mm = 1.0. </p><p>Choice of pitch affects both image quality and patient dose <sup>2</sup>:</p><ul>
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