Impact of the scout view orientation on the radiation exposure and image quality in thoracic and abdominal CT.

OBJECTIVES

To assess the impact of the scout view orientation on radiation exposure and image quality in thoracoabdominal CT, when automated tube voltage selection (ATVS) and automated tube current modulation (ATCM) are used in combination with scan planning on a single scout view.

METHODS

Fifty patients underwent two thoracoabdominal CT examinations, one planned on an anteroposterior scout view, one planned on a lateral scout view. Both examinations included contrast-enhanced imaging of chest (CH) and abdomen (AB) and non-contrast-enhanced imaging of the liver (LI). For all examinations the same imaging protocol was used on the same dual-source CT scanner. The radiation exposure was recorded and objective as well as visual image quality was assessed for all examinations.

RESULTS

The median dose-length product was significantly lower in scans planned on a lateral scout view (CH: 179 vs. 218 mGycm, LI: 148 vs. 178 mGycm, AB: 324 vs. 370 mGy*cm, p < 0.0001). Objective image quality was marginal lower in scans planned on a lateral scout view, whereas the visual image quality was rated as equal.

CONCLUSION

At the tested radiation doses, the orientation of the scout view has a significant impact on the radiation exposure but no clinically relevant impact on the image quality.

KEY POINTS

• The scout view orientation has a significant impact on the radiation exposure. • The scout view orientation has no clinically relevant impact on image quality. • A lateral scout view should be preferred with regard to radiation exposure.