1. Components of CT‐protocols in the 64 included studies.

CT‐protocol components	Number of studies
Slice thickness (mm) 0.6‐2.9 3.0‐4.9 5.0‐6.9 7.0‐10.0 not stated	6 9 36 4 9
Slice interval (mm) 0.6‐2.9 3.0‐4.9 5.0 10.0 not stated	6 5 16 1 36
Voltage (kV) 120 140 200 not stated	21 4 1 38
mAs product (mAs) 30‐100 100‐199 200‐299 ≥ 300 not stated	4 5 5 4 46

CT: computed tomography.
 Atema 2015 was a multi‐centre study including six centres.
 The most commonly used CT‐protocol specified the following: slice thickness 3 mm; voltage 120 kV; and mAs product 165 mAs.
 These values are used in the table.