Experimental observation of ultrasound fast and slow waves through three-dimensional printed trabecular bone phantoms.

The researchers used 3D printing to replicate the micro-structure of a trabecular horse bone to study the ultrasound fast and slow waves propagation through it. They managed to make a highly anisotropic version of the bone structure by elongating the digitized model before 3D printing it. They demonstrated that 3D stereolithography is a promising technique for studying ultrasound propagation in bone.

3D Printing of Trabecular Bone Phantoms

• The researchers conducted ultrasound measurements on 3D printed models of trabecular bone phantoms. These models were created using a 1:1 scale, aiming to replicate the internal structure of horse bone precisely.
• The micro-structure of a trabecular horse bone was first digitized using synchrotron x-ray microtomography. This technology provided a detailed image of the bone microstructure, which was then converted into a 3D binary data set.
• The 3D binary data set was 3D printed to create a physical representation of the bone’s structure. The researchers employed a 3D printing technique called stereolithography, known for its high resolution which is essential for accurately portraying the complex microstructure of trabecular bone.

Ultrasound Propagation through 3D Printed Bones

• The team performed a series of experiments to observe ultrasound propagation through the 3D printed bone model. They used a technique known as “through-transmission” where ultrasound waves were sent through the bone and measured on the other side.
• In addition to this, the researchers created a highly anisotropic version of the trabecular bone model to mimic real anisotropic bone, a typical property of real bones where physical properties are direction dependent.
• During the experiments, both “fast” and “slow” waves were observed to propagate through the trabecular bone phantoms. These wave speed categories are typical of anisotropic genetic material and the presence of both in the model validates the test mechanism.

Implications of the Study

• The results of this study underscore the potential utility of stereolithography and 3D printed bone phantoms for bone research. This practice allows for controlled experiments with customizable bone structures, making it possible to further explore the implications of various bone properties on ultrasound propagation.
• The experiments also showcased the ability of 3D printed models to accurately simulate ultrasound wave propagation as seen in real bone. This could contribute to understanding how different bone structures affect the transportation of sound waves, which could in turn inform techniques employed in medical imaging and therapy.