← CT subtopic / Sim: Pitch & Dose

Pitch & Dose Explorer

Tune kVp, mAs, pitch, and scan length. See CTDIvol, DLP, effective dose, and image noise respond. Toggle automatic exposure control to see how the scanner compensates.

kVp 120 Effective mAs 150 Pitch 1.00 Scan length (cm) 30 Region 0.015

Automatic exposure control (AEC):

CTDIvol

—

mGy

DLP

—

mGy·cm

Effective dose

—

mSv

Relative noise

—

SD (arb)

Teaching notes

CTDIvol is scaled here as mAs × (kVp/120)² ÷ pitch — a reasonable first-order model. With AEC off, raising pitch reduces dose and raises noise proportionally. With AEC on, the scanner raises effective mAs to compensate, erasing most of the noise change at the cost of dose savings. DLP = CTDIvol × scan length; effective dose = DLP × k-factor. Noise scales with 1/√(mAs × pitch).