AJR: Pediatric body size should be assessed before radiation-emitting exams
While fitted average patient sizes are age dependent, predicted individual patient size does not correlate well with age on CT images, said the results of a study published in the June edition of the American Journal of Roentgenology, aimed at modeling optimal x-ray exposure factors in children.
Patricia L. Kleinman, MD, of the department of radiology at Children's Hospital Boston and Harvard Medical School in Boston, and colleagues explained that the "establishment of diagnostic reference levels for children to control and estimate [radiation risks] requires knowledge of patient size as a function of age.”
Between June 20 and Nov. 30, 2007, CT exams and reports of pediatric patients less than 21 years of age performed at Children's Hospital Boston were reviewed by the researchers, who excluded any patients with diseases or technical artifacts that could affect measurements, they wrote.
Of the 1,009 patients included, 54 percent were males. The researchers selected 336 exams each of the head, thorax, abdomen and pelvis, and acquired a total of 2,688 measurements. Data were separated by patient age into 21 groups for statistical analysis, explained the authors.
After reviewing the CT scans, Kleinman and colleagues found that rapid growth of the head occurred from birth to approximately two years, followed by a gradual plateau until age 21. A linear relationship between age and size was established between the thoracic, abdominal and pelvic regions.
In addition, the anteroposterior trunk size growth rate was determined to be relatively region independent, with transverse pelvic dimensions growing more rapidly than the thoracic or abdominal regions and fitted equations showed transverse trunk measurements increased more rapidly than anteroposterior measurements.
“There was a broad overlap of predicted patient size ranges as a function of age within each region,” wrote the authors, noting that they found no significant differences by anatomic region between male and female patients.
Noting that the reliance on age alone could potentially lead to over- or under-radiation exposure to individual pediatric patients, Kleinman said, “The use of a single reference size is inappropriate…Our study suggests that pediatric patient body size should be determined for individual patients before performing diagnostic imaging procedures that entail radiation risks.”
The authors concluded that further studies including patient age, weight and height, would help to reduce other uncertainties with regards to pediatric radiation exposure.
Patricia L. Kleinman, MD, of the department of radiology at Children's Hospital Boston and Harvard Medical School in Boston, and colleagues explained that the "establishment of diagnostic reference levels for children to control and estimate [radiation risks] requires knowledge of patient size as a function of age.”
Between June 20 and Nov. 30, 2007, CT exams and reports of pediatric patients less than 21 years of age performed at Children's Hospital Boston were reviewed by the researchers, who excluded any patients with diseases or technical artifacts that could affect measurements, they wrote.
Of the 1,009 patients included, 54 percent were males. The researchers selected 336 exams each of the head, thorax, abdomen and pelvis, and acquired a total of 2,688 measurements. Data were separated by patient age into 21 groups for statistical analysis, explained the authors.
After reviewing the CT scans, Kleinman and colleagues found that rapid growth of the head occurred from birth to approximately two years, followed by a gradual plateau until age 21. A linear relationship between age and size was established between the thoracic, abdominal and pelvic regions.
In addition, the anteroposterior trunk size growth rate was determined to be relatively region independent, with transverse pelvic dimensions growing more rapidly than the thoracic or abdominal regions and fitted equations showed transverse trunk measurements increased more rapidly than anteroposterior measurements.
“There was a broad overlap of predicted patient size ranges as a function of age within each region,” wrote the authors, noting that they found no significant differences by anatomic region between male and female patients.
Noting that the reliance on age alone could potentially lead to over- or under-radiation exposure to individual pediatric patients, Kleinman said, “The use of a single reference size is inappropriate…Our study suggests that pediatric patient body size should be determined for individual patients before performing diagnostic imaging procedures that entail radiation risks.”
The authors concluded that further studies including patient age, weight and height, would help to reduce other uncertainties with regards to pediatric radiation exposure.