Acquisition Phase

Phase Included

Scan Delay

Respiration Phase

Anatomical Coverage

Non Contrast

Yes

N/A

N/A

to include mastoid cells through petrous ridges

Arterial Phase

N/A

N/A

N/A

N/A

Venous Phase

N/A

N/A

N/A

N/A

Delayed Phase

N/A

N/A

N/A

N/A

Scan Comments: Careful positioning is important to avoid unnecessary exposure to the eyes. All scans are performed using the ALARA principle

 

Technical Parameters

Parameters

kVp

120

Effective mAs

See chart

Time (Rotation)

1.0 sec

Average Acquisition Time

12-15 sec

Collimation

12 x 0.3mm

Pitch Value

0.6

Scan Direction

caudocranial

Comments: Decreasing the display field of view for both the right and the left temporal bones will increase spatial resolution. Scans times are significantly longer then routine scans do to a small collimator size coupled with a low pitch value to increase resolution.

 

Reconstruction Parameters

Soft Tissue

Thin Data

Bone

Slice Thickness

2mm

0.6mm

0.6mm

Reconstruction Spacing

2mm

0.4mm

0.4mm

Reconstruction Algorithm

U30u

U70u

U70u

Window Width and Level

350 / 50

3500 / 500

3500 / 500

Reconstruction Comments:  Reconstructions are done both bilaterally and coned down for each temporal bone. Coronal and sagittal recons are also performed.

 

Contrast Parameters

Parameters

Contrast Type

N/A

Contrast Volume

N/A

Saline Flush

N/A

Injection Rate

N/A

Oral Contrast

N/A

Contrast Volume

N/A

Comments: IV contrast is not routinely necessary.

 

Other Comments: The effective mAs for a pediatric temporal bone CT is calculated using the following chart.

Age

Effective mAs

 CareDose

 

 120 mAs

 

 6mo – 3yrs

 170 mAs

 

 3yrs – 6yrs

260 mAs

 

> 6yrs

 300-350  mAs