Comfort pads that cradle infants during radiographic studies may snugly hold young patients in place, but they also catch x-ray beams before they get to the detector. Removing the pads may open the door for dose reduction, according to a study published in the October issue of Academic Radiology.
“When portable radiographic studies are performed, any beam attenuated/absorbed by the pad occurs after the radiation has already passed through the baby. It is thus unnecessary radiation to the baby, as it does not reach the detector plate that creates the image,” wrote Amit S. Rattan, MD, and Mervyn D. Cohen, MB, ChB, MD, of Riley Children's Hospital and Indiana University School of Medicine in Indianapolis. “Pad removal prior to taking the radiograph may thus be a method of potentially reducing patient radiation.”
Rather than measure the actual radiation at the detector plate, the researchers chose to measure the percent of radiation absorbed or attenuated by the comfort pad. This was accomplished by tracking the exposure index at the detector plate. Since the exposure index increases in a linear manner as mAs is increased, it can provide an accurate determination of the percent of dose absorbed by the comfort pad.
Using thoracic infant phantom models and fixed exposure factors, the authors measured the percentage of radiation absorbed by comfort pads of four different thicknesses, from 0.5 inches to 8 inches.
Results showed radiation beam attenuation ranged from 12 percent to 72.1 percent, reported Rattan and Cohen. As would be expected, increased attenuation occurred with increasing pad thickness.
The authors added that in clinical use, even more x-ray beams could be wasted through attenuation, as pads are sometimes folded to increase thickness and better support individual patients.
Rattan and Cohen wrote that pad removal could allow for appropriate dose reduction or improved image quality if exposure factor is kept constant, but some organizations may feel that removing the pads, especially the thinnest pads that absorbed only 12 percent of radiation, may offer too little benefit to cancel out the loss of support for fragile infants.
“Every neonatal nursery using comfort pads must decide individually how to utilize the results of our study.”