Equivalent number of doses of radiation for most commonly requested investigations. Dose for chest x ray used as single unit dose of radiation. Figures are numbers (percentage) of doctors with correct answer for each investigation

Radiological investigationEquivalent No of chest x raysNo of correct answers (n=130)
Abdominal x ray752 (1.5)
Lumbar spine x ray1203 (2)
Thoracic spine x ray504 (3)
Barium swallow1006 (5)
Peroperative cholangiogram653 (2)
Fixation of fractured neck of femur4510 (8)
Ultrasound of abdomen0124 (95)
CT of abdomen4008 (6)
Spiral CT of abdomen3009 (7)
MRI of abdomen0119 (92)
MRI of knee0119 (92)
MRI of spine0119 (92)
Leg arteriogram4000
Renal arteriogram801 (1)
Thyroid isotope scan508 (6)
White cell scan1502 (1.5)
  • CT=computed tomography; MRI=magnetic resonance imaging.