Mitigation of image distortion during mechanical testing within a dynamic stereo x-ray system

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Materials Science

Background:

• Dynamic Stereo X-ray (DSX) enables precise in-vivo skin strain measurement.
• Validating DSX strain requires mechanical testing within the imaging volume.
• Electromagnetic mechanical testing systems (eMTSs) generate magnetic fields that distort DSX images.

Purpose of the Study:

• To develop and assess a solution for mitigating DSX image distortion caused by eMTS magnetic fields.
• To enable accurate in-vivo skin strain quantification during mechanical testing.

Main Methods:

• A MuMETAL-lined box was designed to divert eMTS magnetic fields from the DSX capture volume.
• A radiopaque object was tested at varying distances (65 and 103 cm) from image intensifiers (IIs).
• eMTS actuator speeds were systematically increased (0.1 to 10 mm/s) during image collection.
• Root Mean Square Error (RSME) was calculated to quantify image distortion.

Main Results:

• Image distortion (RSME) increased with proximity to image intensifiers and higher actuator speeds.
• At 65 cm, the highest speed (10 mm/s) resulted in an RSME of 0.11 mm.
• At 103 cm, RSME remained below 0.05 mm across all tested speeds.

Conclusions:

• The MuMETAL-lined box successfully mitigated DSX image distortion from eMTS magnetic fields.
• The shielding was effective regardless of distance to image intensifiers or actuator speed.
• The achieved RSME values were below the threshold for DSX marker tracking accuracy.