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
Examination | Clinical purpose of CT | Max/min DLP75kg | Max or min DLP75kg protocol | Scan length (cm) | Summary of main protocol differences contributing to variation in DLP75kg |
|---|---|---|---|---|---|
PET/CT brain | Localisation/characterisation | 16.8 | Max | 18 | Exceptionally high effective mAs for localisation/characterisation (images originally intended for diagnostic use) |
Min | 23 | Â | |||
PET/CT and SPECT/CT cardiac | AC only | 19.6 | Max | 29 | High effective mAs for AC only; long scan length |
Min | 16 | Attempted to optimise for AC only with low effective mAs (low mA, high pitch) and low kV; use of IR | |||
SPECT/CT lung | AC only | 27.4 | Max | 32 | High kV; high effective mAs for AC only |
Min | 36 | Attempted to optimise for AC only with low effective mAs (low mA, high pitch); use of IR | |||
Localisation/characterisation | 4.2 | Max | 32 | Higher kV and effective mAs than minimum DLP75kg protocol | |
Min | 33 | Low kV and effective mAs | |||
SPECT/CT bone | Localisation/characterisation | 10.0 | Max | 106 | Three times greater scan length, higher kV and effective mAs than minimum DLP75kg protocol |
Min | 37 | Use of IR | |||
SPECT/CT parathyroid | Localisation/characterisation | 7.8 | Max | 28 | Much higher effective mAs (but lower kV) than minimum DLP75kg protocol |
Min | 24 | Â |