Arm raising at exposure-controlled multidetector trauma CT of thoracoabdominal region: higher image quality, lower radiation dose

Radiology. 2008 Nov;249(2):661-70. doi: 10.1148/radiol.2492080169.


Purpose: To evaluate the effect of arm position on image quality and effective radiation dose in an automatic exposure-controlled (AEC) multidetector thoracoabdominal computed tomography (CT) protocol in trauma patients.

Materials and methods: This retrospective study of the data of 177 trauma patients (117 male; median age, 39 years) was approved by the institutional ethics board, with informed patient consent waived. Patients underwent scanning by using an AEC 16-detector thoracoabdominal CT protocol in which both arms were raised above the shoulder region (standard-position group, 132 patients), one arm was raised and the other was down (one-arm group, 27 patients), or both arms were down (two-arm group, 18 patients). Objective and subjective image quality was assessed. Individual effective radiation dose was calculated from the effective tube current-time product per exposed section. For this purpose, section location-dependent conversion factors were derived by using a CT dosimetry calculator. The effect of arm position on effective dose was quantified by using linear regression analysis with correction for patient volume and attenuation.

Results: Compared with the image quality in the standard-position group, the image quality in the one- and two-arm groups was decreased but within acceptable diagnostic limits. The median corrected effective dose in the standard-position group was 18.6 mSv; the dose in the one-arm group was 18% (95% confidence interval: 11%, 25%) higher than this, and that in the two-arm group was 45% (95% confidence interval: 34%, 57%) higher.

Conclusion: Omitting arm raising results in lower but acceptable image quality and a substantially higher effective radiation dose. Hence, effort should be made to position the arms above the shoulder when scanning trauma patients. Clinical trial registration no. NCT00228111.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Analysis of Variance
  • Arm / physiology*
  • Chi-Square Distribution
  • Female
  • Humans
  • Linear Models
  • Male
  • Middle Aged
  • Posture / physiology*
  • Radiation Dosage
  • Retrospective Studies
  • Tomography, X-Ray Computed / methods*
  • Wounds, Nonpenetrating / diagnostic imaging*

Associated data