Methods to Reduce CT Dose in Pediatric Imaging

Methods to Reduce CT Dose in Pediatric Imaging

Strategies to minimize CT radiation dose in children include judicious use of CT, adjusting scan parameters based on child size, region scanned, and indication. For starters, use two arms of attack.

First, CT should be used judiciously. CT imaging in all patients has increased by 600% over a recent 10-year period. Further, as many as 40% of those pediatric studies are not clearly indicated. To determine the true need for CT examinations, good communication must exist between imagers and those providing pediatric care.

Often, ultrasound or MR can provide the needed diagnostic information while sparring the patient ionizing radiation. Additionally, indicated exams should be carefully protocoled.

Thus, scans should be targeted to the area of concern. This means using a focused renal exam in place of the traditional abdominal pelvis CT when a kidney abnormality is in question.

The second arm of dose reduction lies in modifying CT scan parameters. The routine use of multiple sequences and scans is discouraged. As many as 31% of CT exams are multiphase, and the need for multiphase studies, such as pre- and post-contrast exams, should be determined by the radiologist.

Then specific factors of scan length, slice thickness, and tube current should be adjusted to minimize additional dose delivery.
Other points to consider to reduce CT Dose in pediatric imaging include:

• Tube current and gantry rotation time, as well as detector configuration and kVp, have the most influence on radiation dose.
• Size specific guidelines, usually based on patient height, are available to individualize tube current for various body sites in pediatric patients.
• High contrast regions allow lower tube current.
• As pitch increases, dose decreases. Pitch is determined by table speed, collimation and gantry cycle time in single detector helical CT. Pitches between 1.5 and 2 are appropriate.

Estimates of radiation dose provided by the CT dose index or dose length product are available and some equipment displays the estimates before scanning. Obviously this is beneficial. If adjustments are made to scan parameters, the effect on dose can be identified before the scan is performed and additional requirements made pre-scan.

Long-term strategies to diminish the dose include educating the health care team on the relationship of CT radiation dose, CT parameters, and cancer risk.