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These protocols are based on a 128 slice dual source Siemens CT. Some factors may need to be adjusted for a different CT.

Guideline identity image

CT - PTBs (petrous temporal bones)

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Saphire 2 on all adult reconstructions
Ensure the FoV is the same size on Right and Left axial and coronal reconstructions.
Reconstruct bilateral axial PTBs 0.4mm MPR after scan and send to PACS.
Using the 0.4 mm R and L fine cuts load into 3D and reconstruct a small range of 1x1mm MPR parallel and perpendicular to superior semicircular canals. Send to PACS.

Indication - loss of hearing
- otitis media
- chronic ear infection
- mastoiditis
- osteochondroma
- evaluate
- congenital anomaly
- trauma
Patient Preparation Nil by mouth 4 hours prior if iv contrast or sedation required
Patient Position Head first
PTB Scan
OM line perpendicular
Scan Area From the base of the skull to the top of the mastoid air cells.
Care kV/
Quality ref mAs/
Time per rotation
Care dose 4D on
Care kV on child and semi adult
120 380 1.0
Detector Collimation 0.3
Slice Thickness 0.4  Pitch 0.7
IV Contrast 1 mL Omnipaque 300 per kg if required, maximum 50mls
Scan Delay 2 - 3 minutes
Reconstructions 0.4mm U75u Inner Ear
4mm    U30u Base Orbita
0.4        U75u Inner Ear (Right Ear)
0.4        U75u Inner Ear (Left Ear)
Post Processing Axial        MPR Right PTB 1x1 mm
Coronal   MPR Right PTB 1x1 mm
Axial        MPR Left PTB   1x1 mm
Coronal   MPR Left PTB   1x1 mm
Axial        MPR Bilateral PTBs   0.4  mm

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  • Date last published: 14 December 2017
  • Document type: Imaging Protocol
  • Services responsible: Paediatric Radiology

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