Influence of arm positioning on radiation dose for whole body computed tomography in trauma patients

Multislice whole body computed tomography is regarded as the method of choice for primary investigation of hemodynamically stable patients with multiple injuries. However, a disadvantage of this method is the high level of radiation to which the patient is exposed. Various recommendations on how to position the patient's arms during whole body computed tomography have been given in the literature, but conclusive data are missing. Therefore, the aim of our study was to investigate the relationship between different arm positions and radiation dose in patients undergoing whole body computed tomography.

In a retrospective analysis of available data derived from former whole body computed tomography screening of patients with multiple injuries, we calculated the effective radiation dose and scanning time for different arm positions (both arms up, both arms at sides, right arm up, and left arm up). Statistical analysis was performed using the independent t test with 95% confidence intervals. Statistical significance was set at 0.05.

The data evaluated had been recorded for 956 patients during a period of 18 months. Of these patients, 710 were included in the study. In 487 cases (68%), both arms were up; in 82 cases (12%), down by the sides; in 90 cases (13%), the right arm was up; and in 44 cases (6%), the left arm was up. Overall, the radiation dose was statistically significantly higher with both arms at sides (24.69 mSv ± 6.91 mSv) than with both arms up (19.18 mSv ± 4.99 mSv; p < 0.0000001). Statistically significant differences in effective radiation dose were not found for either the right arm up (23.52 mSv ± 5.23 mSv; p = 0.211) or the left arm up (22.53 mSv ± 5.4 mSv; p = 0.076) compared with both arms down at sides. Comparison of scan lengths for the thorax or abdomen did not yield any significant differences between arms down and any other arm position. Analysis of scanning times did not reveal any significant differences for whole body computed tomography with both arms down (07:31 minutes ± 02:53 minutes) compared with both arms up (07:30 minutes ± 02:04 minutes; p = 0.94), right arm up (07:15 minutes ± 01:43 minutes; p = 0.582), or left arm up (07:18 minutes ± 01:24 minutes; p = 0.707).

Based on our retrospective investigation, it can be recommended with reference to whole body computed tomography screening that the arms should be in the arms-up position during thorax or abdomen scanning of a severely injured patient, provided there are no clear clinical indications of shoulder injury. For the patient, this position is associated with a significantly reduced radiation dose without noticeable loss of time.