Table 4.

A list of the predictors used in mixed effects model B and their origins.

Variable	Description	Source
Categorical predictors
T-shirt size	Estimated t-shirt size of the patient	Calculated
Scanner model	Model of scanner	DICOM header
Patient sex	Gender	DICOM header
Scan protocol	Matched protocol of the series	Calculated
Kernel	Reconstruction kernel	DICOM header
Bowtie filter	Bowtie filter type	DICOM header
Intercept (facility)	Facility that performed the exam	Assigned
Continuous predictors
kVp	Kilo-voltage potential of the x-ray tube	DICOM header
Reconstruction diameter	Diameter of the reconstructed image	DICOM header
Slice thickness	Thickness of reconstructed slice	DICOM header
mAs	Average milli-ampere seconds of the x-ray tube	DICOM header
CTDI*	Radiation output of x-ray tube (*included only in “noise” and “resolution” models)	DICOM Structured Dose Report, or optical recognition of the Dose Report Screen
DLP	Dose-by-scan-length product	DICOM Structured Dose Report, or optical recognition of the Dose Report Screen
Effective size	Effective size of the patient	Calculated
Effective dose	Effective dose to the patient	Calculated
Rotation time	Amount of time of a single revolution of the CT gantry	DICOM header
Max slice thickness	Max thickness of reconstructed slice in acquisition	DICOM header
Total collimation width	The width of the total beam collimation (in mm) over the area of active x-ray detection	DICOM header
Pitch	Pitch of the CT scan	DICOM header
SSDE	Size-specific dose estimate	Calculated
Lateral mis-centering	Offset from isocenter in lateral direction	Calculated
AP mis-centering	Offset from isocenter in anterior-posterior direction	Calculated