Acquisition Phase

Phase Included

Scan Delay

Respiration Phase

Anatomical Coverage

Non Contrast

Yes

N/A

N/A

Base of skull through apex

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: The F/U shunt protocol is performed using a low dose sequential scan to limit patient exposure. Isocentering and properly positioning the patient within the gantry is key to image quality and limiting the radiation dose. If the patient is unable to hold still for the duration of the exam a low dose spiral study can be performed instead to decrease the scan time. All scans are performed using the ALARA principle.

 

Technical Parameters

Parameters

kVp

120

Effective mAs

See chart

Care Dose Reference mAs

N/A

Time (Rotation)

1.0 sec (full)  3.5sec cycle time

Average Acquisition Time

29 sec

Collimation

1 x 5.0mm

Table Feed

14.0 mm

Scan Direction

Caudocranial

Comments: The effective mAs is adjusted using guidelines based upon the patient’s age. The F/U shunt protocol is performed using a low dose sequential scan to limit patient exposure.

 

Reconstruction Parameters

Soft Tissue

Bone

Thin

Slice Thickness

4.8mm

4.8mm

N/A

Reconstruction Spacing

4.8mm

4.8mm

N/A

Reconstruction Algorithm

H30s

H60s

N/A

Window Width and Level

100 / 30

2500/500

N/A

Reconstruction Comments: Proper patient positioning is key to avoid unnecessary exposure to the patient’s eyes.

 

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 necessary for this exam.

 

The effective mAs for a pediatric shunt F/U CT is calculated using the following chart.

Age (years)

Effective mAs

 

  60 mAs

 6 months – 3 yrs

  100 mAs

 3 – 6 yrs

  150 mAs

 >6 yrs

  175 mAs