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Table 3 Comparison of key protocol settings contributing to dose differences between maximum and minimum DLP75kg systems

From: A Nordic survey of CT doses in hybrid PET/CT and SPECT/CT examinations

ExaminationClinical purpose of CTMax/min DLP75kgMax or min DLP75kg protocolScan length (cm)Summary of main protocol differences contributing to variation in DLP75kg
PET/CT brainLocalisation/characterisation16.8Max18Exceptionally high effective mAs for localisation/characterisation (images originally intended for diagnostic use)
Min23 
PET/CT and SPECT/CT cardiacAC only19.6Max29High effective mAs for AC only; long scan length
Min16Attempted to optimise for AC only with low effective mAs (low mA, high pitch) and low kV; use of IR
SPECT/CT lungAC only27.4Max32High kV; high effective mAs for AC only
Min36Attempted to optimise for AC only with low effective mAs (low mA, high pitch); use of IR
Localisation/characterisation4.2Max32Higher kV and effective mAs than minimum DLP75kg protocol
Min33Low kV and effective mAs
SPECT/CT boneLocalisation/characterisation10.0Max106Three times greater scan length, higher kV and effective mAs than minimum DLP75kg protocol
Min37Use of IR
SPECT/CT parathyroidLocalisation/characterisation7.8Max28Much higher effective mAs (but lower kV) than minimum DLP75kg protocol
Min24