T is the nominal width of a section and D(z) is the dose at point z parallel to the z-axis

CTDI measured >100 mm

N is the number of acquired sections per scan, T is the nominal width of each acquired section, and D(z) is the dose at point z parallel to the z-axis

Weighted CTDI

CTDI_{100,center} is the CTDI_{100} measured at the center of the standard CTDI phantom and CTDI_{100,periphery} is the CTDI_{100} measured at the periphery of the phantom

CTDIvol

Pitch is table travel distance per rotation divided by nominal beam width