Monitoring the X-ray dose delivered to patients during diagnostic radiology procedures is an important precursor step in improving patient care. Keith Strauss and colleagues from Cincinnati Children’s Hospital Medical Center compared the dose delivered to children in CT examinations and found statistically significant variation in the mean dose delivered across different types of institutions.
Strauss and colleagues pooled data from 239,622 paediatric CT examinations in the Dose Index Registry from 519 medical imaging centres. They statistically tested the hypothesis that academic paediatric CT providers use diagnostic imaging protocols specifically designed for children that deliver lower radiation doses. The researchers concluded that academic paediatric centres delivered lower radiation dose across all brain examinations, and the majority of chest and pelvis examinations, compared with alternative medical imaging centres (Radiology 10.1148/radiol.2019181753).
The researchers compared patient size-adjusted dose indices across four categories of diagnostic CT providers: academic paediatric, academic adult, non-academic paediatric and non-academic adult. Imaging centres with a medical school affiliation were designated as academic; those listed by the Children’s Hospital Association as paediatric were classified as paediatric facilities.
The team chose to compare three recognised dose indices: the volume CT dose index, the size-specific dose estimate and the dose–length product. To adjust for patient size, the researchers used the patient effective diameter derived from localizer scans, which are used to check patient positioning prior to CT examination. They distributed the data into six patient size categories for chest and pelvic examinations, and five size groups for brain examinations.
Strauss and colleagues used the mean dose index from academic paediatric facilities as a benchmark and compared this value with the mean dose indices from the three remaining categories, using the unequal variance two sample t-test. Since multiple comparisons were made, the researchers also adjusted the confidence level using the Bonferroni correction.
The results showed that across all six patient size groups, and for all three dose metrics, academic paediatric facilities delivered lower mean dose than adult academic, adult non-academic and paediatric non-academic facilities, in 78% of paediatric chest exam comparisons and 89% of comparisons between pelvic exams. For paediatric brain imaging studies, the academic paediatric facilities delivered lower mean dose in all comparisons.
The researchers also compared the variance in the three radiation dose metrics across the different providers. Again, they found that the academic paediatric facilities delivered a less variable dose in the majority of comparisons.
This study highlights the role that effective dose monitoring may have on patient health and outcomes in diagnostic radiology. “Dose management is important for all patients, both paediatric and adult patients. This begins with patient dose monitoring. However, the monitoring step by itself does nothing to improve patient care. Additional steps must be taken to carefully manage the CT radiation of all patients to have a positive impact on patient care,” stresses Strauss.
