Table 2.

Variables associated with radiation exposure

Variable	Measures to minimize radiation
Number of CT scans	Alternative diagnostic modality
	Avoid repeat scans
	Justification of CT scan (avoid young age)
Tube current (mA)	Optimize settings according to patient BMI
Tube voltage (kV)
Pitch	Adjust to patient's heart rate
Tube current modulation
ECG-controlled	Adjust data acquisition to optimal cardiac phase (ECG pulsing window)
Angular-longitudinal	Adjust to patient attenuation profile
Scan length	Minimize
Scan mode
Prospective gating axial (PGA)	Only X-ray switched on during optimal cardiac phase
Retrospective gating helical (RGH)	Optimize tube current modulation