Low Dose Head Computed Tomography Protocol for Evaluation of

Non-traumatic Emergencies in Children

Rishi Mhapsekar, MDMarilyn J. Siegel, MD

Robert McKinstry MD, PhD

Poster # EP-142

Disclosures

• Rishi Mhapsekar: Nothing to disclose

• Marilyn Siegel: Speaker for Siemens Healthcare

• Robert McKinstry: Nothing to disclose

Purpose

• The purpose of our study was to evaluate if an unenhanced low-dose head CT could consistently provide acceptable image quality and diagnostic information

Materials and Methods

• 584 pediatric head CT scans performed

between January 2014 and December 2014

were retrospectively reviewed

• 365 CT scans were performed using a full dose

protocol to assess for traumatic emergencies

and 219 head CT scans were performed using

low dose protocols to evaluate for non-

traumatic emergencies

Materials and Methods

• CT examinations were performed on a 64-slice SOMATOM Definition AS scanner (Siemens Healthcare, Forchheim, Germany) equipped with automated tube-current modulation (CARE Dose4D)

• Full dose scans used quality references of 330 mAs and fixed 120 kV

• Low dose scans used references of 150 mAs and fixed 100 kV

Analysis

• All CT scans were reviewed for patient age, CT Dose

Index Volume (CTDIvol) in mGy, Dose Length

Product (DLP) in mGy.cm, milliamperage (mAs) and

kilovoltage (kVp)

• Data was recorded from the patient dose record

shown at the CT console

• Results of full and low dose scans were analyzed using

Shapiro-Wilk W test and Wilcoxon rank sums test

Qualitative Analysis

• One reader graded image quality

• Diagnostic image quality was graded on a 3 point scale (1, poor and unacceptable; 2, good; 3, excellent)

• Diagnostic acceptability was based on visualization of the sharpness of ventricular outlines, tissue contrast, and shunts (when present)

• Diagnostic noise was graded on a 3 point scale (1, unacceptable; 2, present, but not affecting diagnosis; 3) absent)

Results

• Median patient ages for full and low dose head CT protocols were 8.0 and 6.0 years respectively (p > 0.05)

• Median CTDIvol for full and low dose CT protocols were 28.7 and 8.8 mGy respectively (p < 0.001) (69% difference)

Results

• Median DLP for full and low dose CT protocols were 496 and 146 mGy.cm respectively (p < 0.001) (71% difference)

• Median mAs for full and low dose CT protocols were 295 and 88 mAs respectively (p < 0.001) (70% difference)

ResultsParameter Low Dose

ProtocolFull Dose Protocol

% Change

Median mAs 88 295 70%

Median CTDI 28.7 8.8 69%

Median DLP 146 496 71%

Results

• Low dose pediatric head CTs were of diagnostic image quality - grade 2 or 3 (2, good; 3, excellent)

• Low dose CT noise was graded as 2 or 3 (2, present, but not affecting diagnosis; 3) absent)

Diagnostic Image Quality

Low Dose Full Dose

15 year old girl with headacheCTDI: 11.6; DLP: 164

Diagnostic quality, some noise

16 year old boy with traumaCTDI: 26.8 ; DLP: 582

Diagnostic quality, no noise

Conclusion

• Low dose head CT protocols in children using lower mAs and kV reduce CTDIvol, DLP, and mAs by approximately 70%

• Low-dose non-enhanced head CT provides diagnostically acceptable images in non-traumatic emergencies