OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Combat Casualty Care OBJECTIVE: Design, build and validate a handheld non-contact Laser Near-Infrared Absorption and Photoacoustic Imager (ncNIRPA) in the form of a stand-alone lightweight handheld device, using laser-based measurements, absorption and vibrometry, having optics pathways constructed with integrated photonics technology. DESCRIPTION: Exposure of military to explosions and explosive weapons frequently leads to blast injury, concussions and subconcussions comprising mild traumatic brain injury (mTBI), that has accompanying deleterious and sometimes long-term debilitating effects [1]. More than 449,000 U.S. servicemen suffered from TBIs since 2000, with 82% mTBI [2]. mTBI is often accompanied by intracranial hemorrhage and hematoma containing oxygenated hemoglobin (Hb) and deoxygenated Hb (deoxyHb), that are detectable by NIRS [3]. This project's objective is to employ state-of-the-art technology to produce a novel handheld non-contact laser NIR photoacoustic (PA) imager (ncNIRPA) [4] with real-time imaging capabilities exceeding conventional NIRS devices, and using eye-safe lasers. NIRS devices designed previously, eg. The InfraScan (InfraScan Inc. Philadelphia PA), are limited to a single optode for signal acquisition from a single head location at a time, and require repeated scalp contact [5]. Head burns or trauma complicate use of such NIRS devices. The ncNIRPA imager is a non-contact device. It is directed towards the skull but separated from it, will employ a pulsed NIR laser that is able to detect abnormal accumulation of deoxyHb, producing acoustic vibrations that can be detected through Laser Doppler Vibrometry (LDV), which, in turn, will enable PA imaging [6]. PHASE I: The main goal of Phase I is a feasibility study in the development of a handheld ncNIRPA device. The device laser beam pathways are to be implemented using integrated photonics. Initially, to prove feasibility, a physical, electronics, optical and circuit design of the final handheld ncNIRPA product should be completed as the first deliverable. The major components will include the laser diodes, silicon photonics for laser transmit and receive components, computer processor(s), circuit board, rechargeable battery, transmission antenna, an on/off power switch and display screen. It must be capable to reconstruct an image in near-real-time, i.e. >= 2 Hz, and store DICOM-formatted [8] images. The ncNIRPA should be designed to operate by battery for a minimum threshold of two hours prior to battery recharging or replacement. The physical design of the ncNIRPA must have a form factor of approximately the width and height of a cellphone and be appropriate for the rigors of battlefield use. A second deliverable is a CAD computer model of the imager, accompanied by a physical mock-up of the scanning device. If time permits, a schematic should be developed of the image acquisition and reconstruction software methodology, identifying useful existing software or software to be programmed. PHASE II: The overall objective of Phase II is to produce a fully operational prototype handheld ncNIRPA imager factor that can acquire images from a human head in tests, archive and display the images on the device itself and on external devices so one can retrieve the images from the archive and redisplay them. The first deliverable of Phase II is to produce prototype hardware based on the electronics and optical design of Phase I. This task will produce the first deliverable, a true-size prototype of the ncNIRPA that acquires LDV signals that can be observed on an oscilloscope. The next aim is the programming and testing of software for the imager. The aim of this stage is to produce a second deliverable that is an enhanced form of the first deliverable, now replete with fully operational software for the acquisition of LDV signals, reconstruction of greyscale images, and transmission of the images to an external handheld computer. All image data must be compliant with DICOM standards. Laser power deposition must be demonstrated to not exceed FDA guidelines. The next goal is the production of a fully functional prototype ncNIRPA imager in the desired form factor, complete with the computer software needed to perform signal acquisition and all functions for display, archiving and retrieving the acquired images. This device should be demonstrated to acquire NIR PA images from a healthy human head, under an IRB-approved research protocol. The human subject volunteers should represent a range of cultural backgrounds exhibiting different hair pigments and other hair qualities. The third deliverable is to provide one fully functional prototype, accompanied by validation test reports and other relevant reports and designs, and a proposed regulatory strategy that includes a clear plan on how FDA clearance will be obtained. Early FDA coordination may be considered to assist with regulatory strategy, analysis of manufacturability and commercialization strategy. PHASE III DUAL USE APPLICATIONS: To add value, an aim would be to develop training software, sample input and manuals for the system. Due to the device's small size and likely modest price, the main target for the product is the mass commercial pre-hospital market, i.e., primary care physicians, clinics, and EMT use. Military use would primarily be in Roles One and Two. The regulatory strategy shall be refined and implemented for FDA submission and approval for technical use as an US device. In conjunction with FDA submission, the contractor may develop scaled up manufacturing of the technology that follows FDA quality regulations. Utility is enhanced if the device was easily able to transmit images from phone internet application(s), enabling teleradiology and potentially integrate with artificial intelligence. REFERENCES: 1. McKee AC, ME Robinson, Military-related traumatic brain injury and neurodegeneration, Alzheimers Dement. 2014 June ; 10(3): S242 S253. 2. Agimi Y, LE Regasa, KC Stout, Incidence of traumatic brain injury in the US Military, 20102014. Mil Med 184(5-6) e233-41 (2019). 3. Boas D, MA Franceschini, Near infrared imaging, 2009, http://www.scholarpedia.org/w/index.php?title=Near_infrared_imaging&oldid=61624 4. Hosseinaee Z, M Le, K Bell, P Haji Reza, Towards non-contact photoacoustic imaging [review], Photoacoustics 20, 100207 (2020) 5. Calingo A, Innovative Scanner Designed to Save Marines' Lives on the Battlefield, Marine Corps Systems Command, https://www.marines.mil/News/News-Display/Article/1181027/innovative-scanner-designed-to-save-marines-lives-on-thebattlefield, 12 May 2017. 6. Binte A, E Attia, G Balasundaram, M Moothanchery, US Dinisha, R Bi, V Ntziachristos M Olivoa, A review of clinical photoacoustic imaging: Current and future trends, Photoacoustics 16, 100144 (2019) 7. Medical Imaging & Technology Alliance, https://www.dicomstandard.org KEYWORDS: near-infrared, laser, vibrometry, photonics, imager, photoacoustic, hemorrhage, hematoma, intracranial, portable, non-contact, medical imaging
