Evaluation of ultra-low-dose CT with tin filter for craniosynostosis.

Introduction: CT has replaced skull radiography as the gold standard for assessment of craniosynostosis in children. To minimise the risks of ionising radiation in this radiosensitive population, low-dose CT protocols are increasingly being adopted. This study evaluates the effectiveness of an ultra-low-dose CT protocol with a tin filter in reducing radiation exposure whilst maintaining diagnostic quality for craniosynostosis, and its utility in the evaluation of other findings not appreciable on skull radiography.

Methods: Twenty-seven patients who underwent ultra-low-dose CT for craniosynostosis were compared with an age-matched control group who received standard-dose CT for indications other than craniosynostosis. Differences in radiation dosimetry and quantitative image quality parameters were analysed using independent two-tailed t-tests. Radiologist reports were also examined for the frequency of other incidental radiological findings.

Results: Mean effective dose for the 27 ultra-low-dose CT scans was 0.14 mSv, a 92% reduction compared with the control group. Image quality, measured by contrast-to-noise ratio, was significantly lower in the ultra-low-dose scans compared with the standard-dose scans; however, all scans were diagnostic for detecting or excluding craniosynostosis. Hydrocephalus was able to be ruled out in all 27 ultra-low-dose scans.

Conclusion: Ultra-low-dose CT with a tin filter allows for the diagnosis of craniosynostosis with a 92% dose reduction compared with the standard CT protocol. Despite lower image quality with the ultra-low-dose protocol when compared to standard CT, all 27 scans were adequate for craniosynostosis diagnosis. Additionally, it allowed for the assessment of other relevant findings not appreciable with skull radiography, highlighting its advantages as the new clinical standard for craniosynostosis assessment.