Background <p>Whole-body computed tomography (WBCT) is the preferred first line investigation for patients with suspected multiple traumas. To decrease the potential for increased spinal injury, bearing devices, including trauma mattress, are recommended for adequate spine immobilisation. This study assesses the effect of trauma mattress on the dose and image quality of WBCT examinations.</p> Methods <p>This was a phantom-based experimental study. Two different paediatric whole-body anthropomorphic phantoms from Kyoto Kagaku were used: newborn (PBU-80) and 5-year-old (PBU-70). Optimised WBCT protocols were scanned with and without a trauma mattress. The effective dose (ED) from each protocol was estimated from CT-Expo software and from the product of the dose length product and dose conversion coefficient (DLP-E(k)) methods, while image quality was assessed subjectively and objectively.</p> Results <p>The use of trauma mattress increased the mean ED and decreased the SNR of the 5-year-old phantom examinations by 7.0% (<i>p</i> = 0.776) and 21.4% (<i>p</i> = 0.194) respectively. In contrast, there was a 43.9% increase in ED (<i>p</i> = 0.019) and a 16.5% decrease in SNR (<i>p</i> = 0.221) when trauma mattress was used for the newborn phantom examinations. The differences in the mean ED from CT-Expo and the DLP-E (k) were not statistically significant (<i>p</i> = 0.258 and 0.278 for newborn and 5-year-old phantoms, respectively). The median organ doses estimated from all examinations performed without a trauma mattress were significantly lower than examinations performed with a trauma mattress (<i>p</i> = 0.001). The use of the trauma mattress increased the average tube voltage, tube current, volume computed tomography dose index (CTDI_vol), and the dose-length product (DLP) by 1.3%, 63.9%, 48.3%, and 47.3%, respectively. However, a significant increase was only observed in the tube current (<i>p</i> = 0.014).</p> Conclusion <p>The use of trauma mattress increased the ED and decreased the SNR during the WBCT examinations, albeit at different levels for the newborn and 5-year-old phantoms. Consequently, medical imaging professionals should restrict the use of bearing devices to examinations that justifiably require them. Appropriate adjustments in scan protocols for different body habitus and the use of alternative immobilisation techniques, where necessary, will further enhance patient safety during paediatric WBCT examinations.</p>