3D wrist imaging - Is it time for superman to retire?

Area of Science:

• Medical Imaging
• Radiological Physics

Background:

• Computed tomography (CT) of the wrist presents challenges due to patient positioning, potentially increasing radiation dose from scatter.
• Alternative imaging techniques and patient positions are explored to mitigate radiation exposure.

Purpose of the Study:

• To estimate scatter radiation dose in different phantom positions using helical CT, single-shot CT, and 3D Cone-beam CT (CBCT).
• To compare radiation doses across various clinically relevant positions for wrist CT imaging.

Main Methods:

• An anthropomorphic phantom with wireless electronic dosimeters was used to measure scatter radiation.
• Measurements were taken in multiple positions for helical CT (Superman, semi-superman, wrist on abdomen) and single-shot CT (sitting in front/behind gantry).
• 3D CBCT was evaluated with the phantom in a supine position with the arm extended laterally.

Main Results:

• Helical CT in the Superman pose yielded 64.8 µGy scatter dose.
• The highest dose (269.7 µGy) occurred with the wrist on the abdomen; the lowest (3.2 µGy) was in single-shot CT with the phantom behind the gantry.
• 3D CBCT resulted in a total dose of 171.1 µGy.

Conclusions:

• Commonly used semi-superman and wrist-on-abdomen positions in CT result in the highest scatter doses.
• These positions should be avoided if single-shot CT or 3D CBCT are available.
• Radiographers must consider alternative positions when patients cannot achieve the standard Superman pose for wrist CT.