Radiation Exposure due to CT of the Scaphoid in Daily Practice

Abstract

Study background: The aim of this study was to measure radiation exposure including scatter radiation, resulting from CT of the scaphoid in different settings as used in daily practice and to calculate the effective dose (ED) using a wrist phantom. Methods: The radiation exposure was quantified for five different CT protocols, all used in daily practice for the scaphoid CT. Two protocols concerned a CT of the scaphoid with a plaster cast of the hand and three protocols without. For all protocols the Computed Tomographic Dose Index weighted (CTDIw), the scatter dose to the brain and scatter dose to the torso were derived from the CT and measured externally with the Piranha dose meter. Results: The average CTDIw was 2.18 mGy. The average scatter to the brain and torso was 0.011 mSv. The average estimated ED was 0.02 mSv (range 0.02 to 0.04) of which 0.0008 mSv (range 0.0003 to 0.0012) was due to the scatter radiation. The two CT protocols of the scaphoid performed with a plaster cast resulted in a 90% higher ED, although the power of the study was too low to demonstrate this statistically. Conclusion: The CT protocols used for scaphoid analyses in a plaster cast immobilized hand may result in higher radiation exposure than without plaster cast. We therefore recommend, whenever possible, performing CT of the hand and wrist without a plaster cast.