Table 1.

Patient characteristics and CT scanning parameters

	Standard-dose	Ultralow-dose
Boys/Girls	6/4	10/0
Mean age (years)	13.3 (10–18)	14.5 (12–18)
Mean body surface area (m2)	1.40 (1.07–1.9)	1.56 (1.29–1.94)
Detector configuration (rows × mm)	64 × 0.625	64 × 0.625
Tube potential (kVp)	100	80
Bow tie filter	Body (medium)	Body (medium)
Tube current (mA)	150–200	20
Tube current modulation	Smart mA (x-y-z modulation)	Off
Noise index	13–22	N/A
Gantry rotation time (s)	0.5	0.5
Acquisition mode	Helical	Helical
Helical Pitch	1.375:1	1.375:1
Display field of view (mm)	300	300
Axial image thickness (mm)	3	3
Breath Hold	Inspiration	Expiration
Reconstruction method (% blend)	ASIR (30%)	ASIR (30%) and MBIR (N/A)

ASIR = Adaptive Statistical Iterative Reconstruction, MBIR = Model Based Iterative Reconstruction.