Trauma backboards raise CT rad doses

The list of reservations ED physicians have over keeping patients on spinal-trauma backboards once they’re transported in—prolonged use has been shown to intensify pain, cause pressure ulcers and bring on breathing difficulties—now must include a clear risk of increased radiation dose at CT.

A.Y. Lee, MD, University of California-San Francisco, and colleagues documented the dose spike by scanning an anthropomorphic phantom using automatic tube-current modulation with and without backboards.

Using thermoluminescent dosimeters to measure skin entrance dose in the pelvis and breast, the team found that tube current-time product increased up to 31 percent when the backboard was in place.

In addition, CT dose index (CTDIvol), the weighted average dose measurement in the phantom, increased up to 27 percent.  

Further, with the backboard, the team recorded an increase of up to 25 percent in skin entrance dose in the anterior pelvis.

Skin entrance dose also increased in the breast, although this was not statistically significant.

Concurrently, the team tested the implementation of a multidisciplinary policy to promptly remove patients from backboards upon ED arrival. They found the move cut backboard use from 77 percent to 3 percent.

Their research report posted online Feb. 28 in Clinical Radiology.

“Backboards cause significant photon attenuation from the CT tube when fixed current and fixed voltage are used,” the authors conclude in their discussion. “Although the decision to maintain patients on backboards is multifactorial, attempts should be made to minimize backboard use during CT when possible.”

The study’s limitations included the unfeasibility of accounting for the wide variability of backboard materials and design from one manufacturer to the next, along with the researchers’ sole use of a standard-sized adult male phantom and their use of just two commercially available CT systems.