Opto-acoustic Imaging for Cavitation Detection in blast-induced Traumatic Brain Injury Studies
Abstract
Opto-acoustic Imaging for Cavitation Detection in blast-induced Traumatic Brain Injury To design protective gear for our service men and women from threats involving blast and shock, a validated primary shock damage mechanism is required. There is rising evidence that damage is focused at areas of impedance mismatch, where a shock wave interacts with adjacent tissuesand fluids with differing properties, such as blood vessels and ventricles within brain tissue. Barriers in determining primary blast-induced traumatic brain injury (bTBI) mechanisms are inconsistencies in test objects, varying blast circumstances, and differing tissue geometries. Test objects that are biofidelic and reproducible provide the opportunity to investigate dominantmechanisms at varying blast parameters because they minimize interspecies differences and object to object variation, which are current limitations in animal and cadaver studies. Selecting materials that are transparent allow for optical imaging during the blast at various material interfaces. Using tissue simulants, it may be possible to reproduce a subset of post-mortem diagnostics used in the clinic for adequate comparison of the observed injuries. Cavitation is a suspected mechanism at these tissue interfaces. In order to confirm or rule outthis damage mechanism, studies with +/- controls for cavitation in various materials are needed. Additionally, instrumentation to quantitatively detect cavitation and the resulting damage from a blast is essential. The data obtained from such controlled and repeatable experiments can provide simulation parameters and validation of developed models. At New Mexico Tech (NMT), wehave characterized a variety of transparent materials that more closely mimic the mechanical properties of brain tissue than standard ballistics gels. We have embedded various cavitation nuclei to identify the optical signature of cavitation in these materials. Various geometries with differing complexity will be used to simulate cranial interfaces in two explosively-driven test configurations; specifically, within a blast tube and in the open field. Microscopy will beperformed post-blast, though valuable information may be lost with time, during transport, or during sectioning of the object. For immediate characterization, a field ready and real-time ultrasound imaging system is needed to capture images of the intact test object. For this we propose an Opto-acoustic imaging system that can be configured to acquire data simultaneously in a standard laboratory setting with microscopy or at NMT~s Energetic Materials Research andTesting Center (EMRTC). At the microscopic scale, it will be possible to measure shock parameters as it traverses a material interface and detect cavitation optically and acoustically at high speed. The optical data will provide visualization of the shock front and location of cavitation, while ultrasound can quantify the location and magnitude over a wider field of view. In full scale tests, the key ability provided by ultrasound is the large volume that can be scannedwithout sectioning the object. The capabilities gained with the proposed opto-acoustic imaging system to study bTBI mechanisms are of direct interest to ONR~s Blast and Traumatic Brain Injury Program Area. The ability to scale and observe explosively driven shock-material interactions, similar to those produced by improvised explosive devices (IEDs), is a rare university capability. With the proposed opto-acoustic system, the data obtained from these tests can be maximized and combined with findings at the microscopic scale to further our understanding of damage mechanisms in soft tissues associated with bTBI. With DURIP support, we can make advances in this field to inform simulation and design of protective gear.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 20, 2019
- Source ID
- N000141912677
Entities
People
- Michaelann Tartis
Organizations
- New Mexico Institute of Mining and Technology
- Office of Naval Research
- United States Navy