The patient’s head is positioned in the head holder for most protocols of the head.
When the head holder is not used, a molded sponge is placed directly on the scan table and the patient’s head is positioned within the sponge
The slice angle is determined by the position of the patient’s head (i.e., moving the chin up or down) and the angle of the gantry.
using the supraorbital meatal line (also called the glabellomeatal line) to reduce radiation exposure to the lens of the eye
axial (step and-shoot) techniques are often used for routine brain imaging
the helical CT mode is used mainly for the purpose of generating three- dimensional reformations or to minimize motion-related artifacts.
For most applications concerning structural imaging of the brain and skull base, nonenhanced CT is usually adequate.
Routine scanning of the neck is typically performed with the patient supine and the neck slightly extended. It is most often performed in the helical mode.
The split bolus injection technique is also frequently used for maxillofacial studies in which contrast media is indicated
In neck protocols, the total contrast dose is often split in half
CT angiography has the advantages of being noninvasive and widely available
CT examinations of the spine produce images with inherently high soft tissue contrast. T
Proper localization is essential in scanning the spine.
Thoracic spine DFOV
~16cm
IV contrast for CTA Spine
120 mL at 6mL/s. Scan delay= tracking bolus
Window settings for CTA- COW Carotid
90ww/ 35wl (vertex)
140 ww/ 40 wl (posterior fossa)
250 ww/ 30wl (foramen magnum)
Window settings for CTV, Neck, cervical, thoracic, lumbar spine, and CTA spine
350ww/ 50wl
IV contrast for orbits
100 mL at 1.0 mL/s. Split bolus - Two 50mL injection. 2 min. delay
IV contrast for sella
150 mL at 1.0 mL/s. Scan delay: 75s
IV CONTRAST FOR CTA-COW
60 ml at 4.0 mL/s; 20 ml at 4.0 ml/s. Scan delay= from timing bolus (use carotid artery at ~ level of c4 for ROI
IV contrast for Neck
125 mL at 1.5 mL/s: Split bolus 1st inject 50 mL, 2 minute delay, 75 ml for 2nd; 25s scan initiated
DFOV for Trauma facial bones
18 cm
DFOV for neck
18 cm
DFOV for brain perfusion
25 cm
DFOV for cervical spine
~13
DFOV for CTA spine
20
DFOV for Thoracic spine
~16
DFOV for lumbar spine
14-16
IV contrast for brain perfusion
50 mL (370 concentration) at 4.0 mL; 20 saline flush mL at 4.0 mL/s- 5s delay
IV contrast for CTA-Carotid
80 ml at 4.0ml/s ;40 at 4.0ml/s=scan delay= from timing bolus