Frank E. Talke

Abstract Current spinal pain management procedures, such as radio frequency ablation (RFA) and epidural steroid injection (ESI), rely on fluoroscopy for needle placement which exposes patients and physicians to ionizing radiation. In this paper, we investigate a radiation-free surgical navigation system for spinal pain management procedures that combines magnetic resonance imaging (MRI) with fiducial ArUco marker-based augmented reality (AR) to serve as a radiation-free alternative. High-resolution MRI scans of a lumbar spinal phantom were obtained and assembled as a surface mesh. Laplacian smoothing algorithms were then applied to smoothen the surface and improve the model fidelity. A commercially available stereo camera (ZED2) was used to track single or dual fiducial ArUco markers on the patient to determine the patient's real-time pose. Custom AR software was applied to overlay the MRI image onto the patient, allowing the physician to see not only the outer surface of the patient but also the complete anatomy of the patient below the surface. Needle-insertion trials on a 3D-printed three-vertebra phantom showed that dual ArUco marker tracking increased the accuracy of needle insertions and reduced the average needle misplacement distance compared to single ArUco marker procedures. The average needle misplacement is comparable to the average deviation of 2 mm for conventional epidural techniques using fluoroscopy. Our radiation-free system demonstrates promise to serve as an alternative to fluoroscopy by improving image-guided spinal navigation.

Abstract In this paper, we simulate human soft tissue by developing a composite material consisting of an elastic 3-D printed thermoplastic polyurethane scaffold sheet with corrugations or kirigami patterns embedded in a soft silicone matrix. The strain-stiffening response and the tunability of mechanical properties of this composite were investigated. Uniaxial tensile tests were performed to compare the mechanical characteristics of the novel composite material with the characteristics of porcine vaginal tissue. Composite coupons were stretched to 200% of the original length for both the corrugated and kirigami patterns. Digital image correlation was used to analyze the mechanical behavior, and true stress and true stretch response data were recorded. The soft composite coupons were shown to be tunable and displayed tissue-like strain-stiffening. Stiffness variation of sinusoidal corrugations was found to be a function of the sinusoidal wavelength, sinusoidal amplitude, and thermoplastic polyurethane sheet thickness. Stiffness variation of kirigami patterns was influenced by pattern type and direction of load. A custom soft composite was tuned to match the mechanical properties of porcine vaginal tissue. The composites developed in this research can be used as soft tissue substitutes for medical device calibration, medical device testing, and physician training.

Abstract Vaginal stenosis is a painful condition characterized by narrowing and shortening of the vaginal canal following radiation therapy for cervical cancer. Current stenosis treatments rely on rigid dilators that suffer from low patient compliance due to discomfort. This paper presents the development of a personalized, multi-balloon dilator tailored to the severity and location of stenosis. We introduce two design concepts: a hand-held device for patient self-use and a desktop system for physician-guided therapy. To enhance comfort, especially in severe cases of occlusion, the dilator can be miniaturized while maintaining multi-balloon functionality. This poses design and manufacturing challenges, including the need for mechanical constraints to ensure targeted inflation without leakage. We explored various constraint designs and optimized the silicone molding process to improve balloon integrity, achieve uniform inflation, and reduce manufacturing time. Device reliability was evaluated through cyclical inflation testing, and future clinical testing is planned. These advancements represent important steps toward a patient-friendly solution for vaginal dilation therapy.

Current spinal pain management procedures, such as radiofrequency ablation (RFA) and epidural steroid injection (ESI), rely on fluoroscopy for needle placement which exposes patients and physicians to ionizing radiation. In this paper, we investigate a radiation-free surgical navigation system for spinal pain management procedures that combines magnetic resonance imaging (MRI) with fiducial ArUco marker-based augmented reality (AR). High-resolution MRI scans of a lumbar spinal phantom were obtained and assembled as a surface mesh. Laplacian smoothing algorithms were then applied to smoothen the surface and improve the model fidelity. A commercially available stereo camera (ZED2) was used to track single or dual fiducial ArUco markers on the patient to determine the patient's real-time pose. Custom AR software was applied to overlay the MRI image onto the patient, allowing the physician to see not only the outer surface of the patient but also the complete anatomy of the patient below the surface. Needle-insertion trials on a 3D-printed 3-vertebra phantom showed that dual-ArUco marker tracking increased the accuracy of needle insertions and reduced the average needle misplacement distance compared to single-ArUco marker procedures. The average needle misplacement is comparable to the average deviation of 2 mm for conventional epidural techniques using fluoroscopy. Our radiation-free system demonstrates promise to serve as an alternative to fluoroscopy by improving image-guided spinal navigation.

Computer-assisted surgical navigation techniques have become increasingly more important in healthcare.Navigation systems are designed to improve surgical accuracy, safety, and efficiency for various invasive procedures.In this paper, we design a lowcost 3D navigation system utilizing augmented reality (AR) and computer vision (CV) for pain management of spinal procedures such as radiofrequency ablation (RFA) and epidural steroid injection (ESI).Simulated spinal injection experiments are performed and the accuracy of the proposed AR approach is assessed.The results show that augmented reality is a useful tool in surgical navigation and can serve as a cost-effective alternative to fluoroscopy.

Abstract Computer-assisted surgical navigation systems have gained popularity in surgical procedures that demand high amounts of precision. These systems aim to track the real-time positioning of surgical instruments in relation to anatomical structures. Typically, state-of-the-art methods involve tracking reflective 3D marker spheres affixed to both surgical instruments and patient anatomies with infrared cameras. However, these setups are expensive and financially impractical for small healthcare facilities. This study suggests that a fully optical navigation approach utilizing low-cost, off-the-shelf parts may become a viable alternative. We develop a stereoscopic camera setup, costing around $120, to track and monitor the translational movement of open-source based fiducial markers on a positioning platform. We evaluate the camera setup based on its reliability and accuracy. Using the optimal set of parameters, we were able to produce a root mean square error of 2 mm. These results demonstrate the feasibility of real-time, cost-effective surgical navigation using off-the-shelf optical cameras.

Abstract A novel detachable bronchoscope with a 3D printed micro-transmission is investigated. The micro-transmission controls the motion of the tip of the bronchoscope and is embedded in one end of the flexible insertion section of the bronchoscope. The micro-transmission allows manipulation of the distal end through the translation of guide nuts that are connected to the tip of the bronchoscope through so-called “angulation” wires. The displacement of the guide nuts on the left and right-handed screw sections and the control of the distal end of the bronchoscope are investigated. The maximum tensile force on the angulation wire before failure is determined experimentally for different screw pitches.

There are more than 13,000 new cases of cervical cancer each year in the United States and approximately 245,000 survivors. External beam radiation and brachytherapy are the front-line treatment modalities, and 60% of patients develop vaginal damage and constriction, i.e., stenosis of the vaginal vault, greatly impeding sexual function. The incidence of vaginal stenosis (VS) following radiotherapy (RT) for anorectal cancer is 80%. VS causes serious quality of life (QoL) and psychological issues, and while standard treatment using self-administered plastic dilators is effective, acceptance and compliance are often insufficient. Based on published patient preferences, we have pursued the design of a soft inflatable dilator for treating radiotherapy-induced vaginal stenosis (VS). The critical component of the novel device is the dilator balloon wall material, which must be compliant yet able to exert therapeutic lateral force levels. We selected a commercially available silicone elastomer and characterized its stress-strain characteristics and hyperelastic properties. These parameters were quantified using uniaxial tensile testing and digital image correlation (DIC). Dilator inflation versus internal pressure was modeled and experimentally validated in order to characterize design parameters, particularly the dilator wall thickness. Our data suggest that an inflatable silicone elastomer-based vaginal dilator warrants further development in the context of a commercially available, well-tolerated, and effective device for the graded, controlled clinical management of radiotherapy-induced VS.

<title>Abstract</title> Computer-assisted surgical navigation systems have gained popularity in surgical procedures that demand high amounts of precision. These systems aim to track the real-time positioning of surgical instruments in relation to anatomical structures. Typically, state-of-the-art methods involve tracking reflective 3D marker spheres affixed to both surgical instruments and patient anatomies with infrared cameras. However, these setups are expensive and financially impractical for small healthcare facilities. This study suggests that a fully optical navigation approach utilizing low-cost, off-the-shelf parts may become a viable alternative. We develop a stereoscopic camera setup, costing around $120, to track and monitor the translational movement of open-source based fiducial markers on a positioning platform. We evaluate the camera setup based on its reliability and accuracy. Using the optimal set of parameters, we were able to produce a root mean square error of 2 mm. These results demonstrate the feasibility of real-time, cost-effective surgical navigation using off-the-shelf optical cameras.

Surgical navigation technologies have transformed the healthcare landscape, playing a key role in enhancing precision, safety, and efficiency of various medical procedures. In this paper, we present a costeffective 3D computer navigation approach that leverages augmented reality (AR) and computer vision (CV) to aid in spinal pain management procedures like radiofrequency ablation (RFA) and epidural steroid injections (ESI). We evaluate the accuracy of AR overlay of key anatomical features on the patient (obtained from MRI scans or CAD models of the patient) through simulated spinal injection experiments and assess the accuracy of the CV algorithm via optical tracking experiments. Our findings indicate that ARand CV are valuable tools for surgical guidance, offering a low-cost alternative to traditional fluoroscopy.

PURPOSE/OBJECTIVE(S) Chemoradiation therapy (CRT) is the standard of care for the treatment of locally advanced cervical cancer (LACC). Vaginal stenosis (VS) is a common side effect of CRT and leads to sexual dysfunction, pain, and difficulty with vaginal intercourse, resulting in decreasing quality-of-life (QOL). However, there is scant data on the timeline of VS development, and patient use and satisfaction with a standard vaginal dilator (VD). In this study, we plan to develop a standardized technique to assess VS using physical exam measurements at specified timepoints after CRT. Secondarily, we will assess patient preferences and use of available VDs with the goal of developing a novel VD device with our multidisciplinary engineering team. We report the rationale, methods, and objectives of this clinical study. MATERIALS/METHODS Patients with LACC treated with CRT and brachytherapy are eligible. CT-based imaging pre-CRT and 3-months post-CRT to assess radiographic changes in the vaginal length and width will be collected. Vaginal measurements and physical exam will be recorded at baseline and 3-, 6-, and 12-months following CRT. Patients will also be given a set of VDs that range in diameter and length. Patient vaginal capacity, defined as the largest VD that can be comfortably accommodated in the vagina during pelvic exam, and compliance with VD use will be recorded at each visit. Patients will be given the EORTC Sexual Health Questionnaire (EORTC SHQ-22). Toxicity grading will use the CTCAE v5. We plan to assess patient preference using a VD-specific questionnaire to help guide the development of a personalized VD. RESULTS For the primary analysis, we will examine the VS CTCAE v5 toxicity at baseline vs 1 year for 20 patients. The sample size we propose is sufficient to achieve at least 80% power at 5% significance level for detecting a significant non-zero proportion with a margin of 20%. For the secondary analysis, we will test the Spearman's coefficient and Kendall's tau between VS CTCAE and EORTC questions: "has the treatment affected your sexual activity?"; "have you felt pain during/after sexual activity?"; "have you been sexually active?" We will use permutation tests in which the ID will be permuted for vaginal stricture but kept as original for the EORTC questions. We will test the null hypothesis of no correlation by comparing the observed Spearman's coefficient and Kendall's tau to the permutation distributions. We plan to incorporate the specific VD questionnaire responses into the development of a novel device using qualitative measures. CONCLUSION This clinical trial is an observational cohort study that aims to quantify CRT-induced VS, obtain patient reported sexual health, and understand specific preferences and compliance with VD use for the development of a novel engineered device.

Abstract Computer-assisted navigation has become a popular solution in surgical procedures where a high amount of precision is required. Current state-of-the-art methods of surgical navigation involve tracking reflective 3D marker spheres using IR stereo-scopic cameras. However, the cost of implementing such systems may not be affordable for smaller healthcare systems. In this paper, we propose that fully optical navigation has the potential to be a viable alternative to state-of-the-art reflective marker navigation. We use fiducial ArUco markers to facilitate the tracking of real-time position. Using two inexpensive cameras, we design and calibrate a stereoscopic camera to record the 3D position of an ArUco marker moving through space along a positioning platform. Additionally, we explore the possibility of using different color spaces and physical marker colors to improve the detection percentage and accuracy of markers. We identified that black-and-white ArUco markers using the Hue, Saturation, and Lightness (HSL) color space gave a positional mean error of 5.38 mm. Using the Red, Green, and Blue (RGB) color space gave the highest detection percentage for the same ArUco markers. In the future, the mean error can be reduced by increasing camera quality and by using a multi-stereoscopic camera setup.

Abstract This paper proposes a novel design approach for a composite emulating the strain hardening and anisotropic mechanical characteristics of normal and abnormal vaginal tissue. The realized composite consisted of a soft elastomeric silicone matrix integrated with a thermoplastic polyurethane 3D scaffold. The strain-hardening effect of vaginal tissue was attained by altering the scaffold’s gyroid structure. As the composite deformed, the mechanical response changed from silicone-dominated to polyurethane-dominated. The anisotropic properties of the composite were created by introducing anisotropy in the gyroid structure to replicate the effects of various collagen fiber orientations in vaginal tissue. Changes in mechanical behavior were quantified using uniaxial tensile testing. Three types of distorted gyroids were examined, x-axis lengthened, y-axis lengthened, and x and y-axis lengthened unit cells.

Abstract To improve the prospect of self-examining ophthalmic devices, we have previously developed a handheld 3-in-1 device consisting of a non-contact tonometer, visual acuity tester, and slit lamp biomicroscope [1]. For validating the tonometer measurement principle, we have developed an artificial cornea and manometer test stand using different silicone materials to study the deflection of the cornea as a function of the intraocular pressure (IOP) inside the human eye. Young’s moduli for all materials were evaluated and compared with that of human cornea. The intraocular pressure was varied between 0 and 40 mmHg and tested with both a commercial and the 3-in-1 device’s tonometer. Results from both devices validate the use of such a phantom eye apparatus to test similar ophthalmic instrumentation before clinical testing on humans.

State-of-the-art computer-assisted surgery relies on infrared-based cameras for precise positional measurements. However, the cost of purchasing these systems acts as a barrier for smaller healthcare facilities to adopt them. Recently, low-cost optical tracking with cameras has emerged as a promising alternative, but differences in operating room conditions and patient anatomy can cause inconsistencies between procedures. Therefore, it is essential to identify and evaluate individual factors that may affect a procedure. In this study, we evaluate fiducial ArUco markers as a low-cost alternative to traditional markers. To evaluate their effectiveness, we designed a ground truth testing platform, which enables us to measure the real-time difference between the predicted and actual positions. We investigated the effects of warping, line-of-sight obstruction, and operating room lighting as variables that could influence marker tracking in the operating room. Each variable was isolated and simplified to quantifiable modifications to the physical marker and X-Y platform environment. We find that our navigation system is a promising approach for use in computer-navigated surgery, and future work will focus on implementing image processing techniques to improve the accuracy of optical marker tracking.

This paper presents the design of a new portable ophthalmic device, the so-called 3-in-1 device, that allows patients to self-examine their eyes. The device combines the three most essential ophthalmic examinations: slit lamp biomicroscopy to examine the anterior segment of the eye, visual acuity measurement to determine the quality of vision, and non-contact tonometry to assess the intraocular pressure of the eye. The aim of the device is to enable the patient to perform these standard examinations in the comfort of his home and to send the results via the internet to the ophthalmologist for further evaluation. Within the scope of this work, the first prototype of the 3-in-1 device was designed and manufactured. The slit lamp examination procedure can be recorded by a video camera and the footage can be used by an ophthalmologist to check for abnormalities in the anterior chamber of the eye. The visual acuity screener has been designed to be performed under the same conditions as a conventional visual acuity examination by an ophthalmologist. For this function an optical lens system was developed which projects the optotypes to a test distance of 6m. The non-contact tonometer evaluates the degree of deformation of the patient's cornea using machine learning algorithms to draw conclusions about the intraocular pressure. Ultimately, the goal of the device is to improve accessibility to ophthalmic care and the frequency with which examinations are performed in order to detect eye diseases and abnormalities earlier.