Transducer Placement Research Articles

Numerical investigation of ultrasonic cleaning in the rubber glove industry: A comparison of the linear helmholtz and commander-prosperetti models

Ultrasonic cleaning is an effective industrial method that enhances cleaning efficiency by reducing the time and chemicals needed. In the glove manufacturing sector, ultrasound accelerates cleaning, even without harsh chemicals. This study optimises ultrasonic cleaning systems specifically for ceramic glove formers through cavitation, which occurs when acoustic pressure exceeds Blake's threshold. The research compares two acoustic models: Linear Helmholtz and Commander and Prosperetti (CP), to simulate and enhance acoustic pressure fields in ultrasonic tanks. Finite Element Method (FEM) simulations using COMSOL Multiphysics assessed various factors, such as tank dimensions, transducer placements, and attenuation coefficients, on system performance. Results showed that the CP model provides a more accurate representation of acoustic pressure distribution by incorporating bubble dynamics and sound wave attenuation, while the Linear Helmholtz model tends to overestimate pressures. Simulations indicated that placing glove formers directly above transducers optimises pressure fields in the CP model, while the Helmholtz model preferred positioning them between transducers. Energy efficiency evaluations revealed approximately 58.33 W of energy required per glove former, achieving a power density of 7.41 W L⁻¹. This research highlights the importance of balancing acoustic pressure and energy efficiency for effective ultrasonic cleaning systems in industrial applications.

Voiding sonography: Technical description of a novel ultrasound method for assessment of micturition in women

AbstractVoiding sonography (VS) is a novel non‐invasive method that can be used to assess micturition in real time. When performed in a functional seated position and combined with free uroflowmetry, detailed evaluation of voiding can be conducted. VS presents advantages over current invasive assessment methods such as urodynamics. This methodological paper describes the rationale; advantages and disadvantages of VS; participant preparation; technique; a practical approach to obtain the video/image (including transducer placement to achieve an assessment of voiding with minimal obstruction of urine flow); recommended machine and transducer specifications; and the potential usefulness of ultrasound measurements. These measurements might provide information regarding the function of the pelvic floor muscle and urethral dynamics during voiding. Measures assessed with VS can also provide information regarding urine storage. In summary, VS is a new method to assess female voiding. Future work should evaluate the potential utility of the method to evaluate characteristics and mechanisms for voiding dysfunction in females with a variety of relevant clinical conditions. Use of VS as a screening tool before and after surgical or non‐surgical treatment intervention may also be a future consideration to assess progress and provide feedback to clinicians and patients.

Multi-modal networks for real-time monitoring of intracranial acoustic field during transcranial focused ultrasound therapy

Background and objective:Transcranial focused ultrasound (tFUS) is an emerging non-invasive therapeutic technology that offers new brain stimulation modality. Precise localization of the acoustic focus to the desired brain target throughout the procedure is needed to ensure the safety and effectiveness of the treatment, but acoustic distortion caused by the skull poses a challenge. Although computational methods can provide the estimated location and shape of the focus, the computation has not reached sufficient speed for real-time inference, which is demanded in real-world clinical situations. Leveraging the advantages of deep learning, we propose multi-modal networks capable of generating intracranial pressure map in real-time. Methods:The dataset consisted of free-field pressure maps, intracranial pressure maps, medical images, and transducer placements was obtained from 11 human subjects. The free-field and intracranial pressure maps were computed using the k-space method. We developed network models based on convolutional neural networks and the Swin Transformer, featuring a multi-modal encoder and a decoder. Results:Evaluations on foreseen data achieved high focal volume conformity of approximately 93% for both computed tomography (CT) and magnetic resonance (MR) data. For unforeseen data, the networks achieved the focal volume conformity of 88% for CT and 82% for MR. The inference time of the proposed networks was under 0.02 s, indicating the feasibility for real-time simulation. Conclusions:The results indicate that our networks can effectively and precisely perform real-time simulation of the intracranial pressure map during tFUS applications. Our work will enhance the safety and accuracy of treatments, representing significant progress for low-intensity focused ultrasound (LIFU) therapies.

Using bone conduction brainstem auditory evoked response tests in gray seals (Halichoerus grypus)

Gray seals (Halichoerus grypus) outer ears close when sedated, requiring appropriate methods to test hearing, circumventing the outer and middle ear (air conduction). Anthropogenic noise exposure (e.g., offshore windfarms) in the marine environment is a risk to seals, requiring appropriate methods for testing hearing. Bone Conduction Brainstem Auditory Evoked Response (BC-BAER) was investigated in six gray seals to characterize responses elicited by different acoustic stimuli, evaluate the potential of using BC-BAER to estimate hearing sensitivity, and best placement of the bone transducer. Seals were tested in December 2023 and February 2024 during ongoing research at the Sea Mammal Research Unit, University of St. Andrews, Scotland. BC-BAER measurements in six seals using broadband click and gated tone bursts stimuli had responses from 250 to 8000 Hz, the limits of the RadioEar-B71 bone transducer. Visual identification of Wave V was used to estimate hearing thresholds. Average threshold values were 45.67 dB re 20 µPa for tone bursts at 8000 Hz, the maximum sensitivity of frequencies tested. Recording of BC-BAER is a viable means of studying hearing in gray seals with the best placement of the RadioEar-B71 bone transducer being the zygomatic process compared to the mastoid.

Toward Wearables for Bruxism Detection: Voluntary Oral Behaviors Sound Recorded Across the Head Depend on Transducer Placement.

Bruxism is a parafunctional orofacial behavior. For diagnosis, wearable devices that use sounds as biomarkers can be applied to provide the necessary information. Human beings emit various verbal and nonverbal sounds, making it challenging to identify bruxism-induced sounds. We wanted to investigate whether the acoustic emissions of different oral behaviors have distinctive characteristics and if the placement of the transducer has an impact on recording the sound signals. Sounds from five oral behaviors were investigated: jaw clenching, teeth grinding, reading, eating, and drinking. Eight transducers were used; six were attached to the temporal, frontal, and zygomatic bones with the aid of medical tape, and two were integrated into two commercial earphones. The data from 15 participants were analyzed using time-domain energy, spectral flux, and zero crossing rate (ZCR). In summary, all oral behaviors showed distinct characteristic features except jaw clenching, though there was a peak in the recording, possibly due to tooth tapping, before its expected onset. For teeth grinding, the transducer placement did not have a significant impact (p > 0.05) based on energy, spectral flux, and ZCR. For jaw clenching, the transducer placement had an impact with regard to spectral flux (p < 0.01). For reading and eating, the transducer placement had a significant impact with regard to energy (p < 0.05 for reading, p < 0.01 for eating), spectral flux (p < 0.001 for reading, p < 0.01 for eating), and ZCR (p < 0.001 for both reading and eating). For drinking, the transducer placement only had a significant impact with regard to ZCR (p < 0.01). We were able to record the sounds of various oral behaviors from different locations on the head. However, the ears were an advantageous location to place the transducer, since they could compensate for various head movements and ear devices are socially tolerable.

Branch spiral beam harvester for uni-directional ultra-low frequency excitations

In recent years, there has been a growing interest in piezoelectric energy harvesting systems, particularly for their potential to recharge or replace batteries in energy-efficient electronic devices and wireless sensor networks. Nonetheless, the conventional linear piezoelectric energy harvesters (PEH) face limitations in ultra-low frequency vibrations (1–10 Hz) due to their narrow operating bandwidth and higher resonance frequencies. To address this, researchers explored compact shaped geometries, with spiral PEH being one such design to lower resonance frequencies by reducing structural stiffness. While trying to achieve this lower resonance frequency, spiral designs overlooked that they were spreading the stress across the structure. This was a significant drawback because it reduced the structure's ability to stress the piezoelectric transducer. The issue remains unaddressed, limiting the power generation of spiral beam harvesters. Furthermore, spiral structures also fail to broaden the operating bandwidth, posing additional constraints on their effectiveness. This study introduces a novel solution – the “branch spiral beam harvester,” combining the benefits of both spiral and branch beam designs. The integration of the branch beam concept into the spiral structure aimed to broaden the effective frequency range and establish a concentrated stress area for the placement of the piezoelectric transducer. Finite Element Analysis (FEA) was employed to assess operating bandwidth and stress distribution, while experimental studies evaluated voltage and power generation. Once the workability was confirmed, a statistical optimisation method was introduced to tailor the harvester for specific frequencies in the ultra-low frequency range. Results indicated that the branch spiral beam harvester exhibits a wider operating bandwidth with six natural frequencies in the ultra-low frequency range. It harnessed significantly higher output voltages and power compared to conventional linear PEH. This innovation presents a promising advancement in piezoelectric energy harvesting, offering improved performance without the need for proof masses or additional accessories.

Model-based navigation of transcranial focused ultrasound neuromodulation in humans: Application to targeting the amygdala and thalamus

BackgroundTranscranial focused ultrasound (tFUS) neuromodulation has shown promise in animals but is challenging to translate to humans because of the thicker skull that heavily scatters ultrasound waves. ObjectiveWe develop and disseminate a model-based navigation (MBN) tool for acoustic dose delivery in the presence of skull aberrations that is easy to use by non-specialists. MethodsWe pre-compute acoustic beams for thousands of virtual transducer locations on the scalp of the subject under study. We use the hybrid angular spectrum solver mSOUND, which runs in ∼4 s per solve per CPU yielding pre-computation times under 1 h for scalp meshes with up to 4000 faces and a parallelization factor of 5. We combine this pre-computed set of beam solutions with optical tracking, thus allowing real-time display of the tFUS beam as the operator freely navigates the transducer around the subject’ scalp. We assess the impact of MBN versus line-of-sight targeting (LOST) positioning in simulations of 13 subjects. ResultsOur navigation tool has a display refresh rate of ∼10 Hz. In our simulations, MBN increased the acoustic dose in the thalamus and amygdala by 8–67 % compared to LOST and avoided complete target misses that affected 10–20 % of LOST cases. MBN also yielded a lower variability of the deposited dose across subjects than LOST. ConclusionsMBN may yield greater and more consistent (less variable) ultrasound dose deposition than transducer placement with line-of-sight targeting, and thus could become a helpful tool to improve the efficacy of tFUS neuromodulation.

TFUSFormer: Physics-Guided Super-Resolution Transformer for Simulation of Transcranial Focused Ultrasound Propagation in Brain Stimulation.

Transcranial focused ultrasound (tFUS) has emerged as a new mode of non-invasive brain stimulation (NIBS), with its exquisite spatial precision and capacity to reach the deep regions of the brain. The placement of the acoustic focus onto the desired part of the brain is critical for successful tFUS procedures; however, acoustic wave propagation is severely affected by the skull, distorting the focal location/shape and the pressure level. High-resolution (HR) numerical simulation allows for monitoring of acoustic pressure within the skull but with a considerable computational burden. To address this challenge, we employed a 4× super-resolution (SR) Swin Transformer method to improve the precision of estimating tFUS acoustic pressure field, targeting operator-defined brain areas. The training datasets were obtained through numerical simulations at both ultra-low (2.0 [Formula: see text]) and high (0.5 [Formula: see text]) resolutions, conducted on in vivo CT images of 12 human skulls. Our multivariable datasets, which incorporate physical properties of the acoustic pressure field, wave velocity, and skull CT images, were utilized to train three-dimensional SR models. We found that our method yielded 87.99 ± 4.28% accuracy in terms of focal volume conformity under foreseen skull data, and accuracy of 82.32 ± 5.83% for unforeseen skulls, respectively. Moreover, a significant improvement of 99.4% in computational efficiency compared to the traditional 0.5 [Formula: see text] HR numerical simulation was shown. The presented technique, when adopted in guiding the placement of the FUS transducer to engage specific brain targets, holds great potential in enhancing the safety and effectiveness of tFUS therapy.

Development of Photonic Smart Veil for Structural Health Monitoring

The use of fiber optics as structural health monitoring (SHM) systems is now widespread. This technology is ideal for the creation of monitoring algorithms thanks to the creation of individual Bragg grating sensors (FBGS) or arrays of sensors, the small size, durability, real-time monitoring capabilities, and the ability to place these elements within composite structures. One of the issues in using FBG sensors is the placement of these local transducers at the point where measurement is to be made, during the composite component creation process. Positioning a sensor array along a complex path in the lamination sequence and ensuring that the position of the sensors is maintained during the autoclave curing process is a decisive challenge to enable this technology to spread rapidly in the market. Starting with the configuration of the Quick Pack, a thin membrane that incorporates optical fiber, methods of manufacturing the component were improved by minimizing its size to reduce its invasiveness. New materials to incorporate the optical fiber and different configurations to reduce its stiffness were considered. Configurations with different degrees of polymerization of the constituent materials were studied to improve the adhesion of the component to the composite structure. To validate the performance improvement, specimens were created in order to perform peel tests (ASTM D 3167-10). The results demonstrate the improvement in adhesion and the advantage of including the partially cured element in the lamination sequence. Further prototyping identified the minimum degree of polymerization required to hold the optical fiber in place. This new transducer, Photonic Smart Veil, allows FBG sensors to be properly inserted in the desired positions and locked in place during the production of composite components, improving their performance.

Ultrasound‐based bone tracking using cross‐correlation enables dynamic measurements of knee kinematics during clinical assessments

AbstractPurposeMeasuring joint kinematics in the clinic is important for diagnosing injuries, tracking healing and guiding treatments; however, current methods are limited by accuracy and/or feasibility of widespread clinical adoption. Therefore, the purpose of this study was to develop and validate an ultrasound (US)‐based method for measuring knee kinematics during clinical assessments.MethodsWe mimicked four clinical laxity assessments (i.e., anterior, posterior, varus, valgus) on five human cadaver knees using our robotic testing system. We simultaneously collected B‐mode cine loops with an US transducer. We computed the errors in kinematics between those measured using our bone‐tracking algorithm, which cross‐correlated regions of interest across frames of the cine loops, and those measured using optical motion capture with bone pins. Additionally, we conducted studies to determine the effects of loading rate and transducer placement on kinematics measured using our US‐based bone tracking.ResultsPooling the trials at experimental speeds and those downsampled to replicate clinical laxity assessments, the maximum root‐mean‐square errors of knee kinematics using our bone‐tracking algorithm were 2.2 mm and 1.3° for the anterior‐posterior and varus‐valgus laxity assessments, respectively. Repeated laxity assessments proved to have good‐to‐excellent repeatability (intraclass correlation coefficients [ICCs] of 0.81–0.99), but ICCs from repositioning the transducer varied more widely, ranging from poor‐to‐good reproducibility (0.19–0.89).ConclusionOur results demonstrate that US is capable of tracking knee kinematics during dynamic movement. Because US is a safe and commonly used imaging modality, when paired with our bone‐tracking algorithm, US has the potential to assess dynamic knee kinematics across a wide variety of applications in the clinic.Level of EvidenceNot applicable.

SonoMyoNet: A Convolutional Neural Network for Predicting Isometric Force from Highly Sparse Ultrasound Images.

Ultrasound imaging or sonomyography has been found to be a robust modality for measuring muscle activity due to its ability to image deep-seated muscles directly while providing superior spatiotemporal specificity compared to surface electromyography-based techniques. Quantifying the morphological changes during muscle activity involves computationally expensive approaches for tracking muscle anatomical structures or extracting features from brightness-mode (B-mode) images and amplitude-mode (A-mode) signals. This paper uses an offline regression convolutional neural network (CNN) called SonoMyoNet to estimate continuous isometric force from sparse ultrasound scanlines. SonoMyoNet learns features from a few equispaced scanlines selected from B-mode images and utilizes the learned features to estimate continuous isometric force accurately. The performance of SonoMyoNet was evaluated by varying the number of scanlines to simulate the placement of multiple single-element ultrasound transducers in a wearable system. Results showed that SonoMyoNet could accurately predict isometric force with just four scanlines and is immune to speckle noise and shifts in the scanline location. Thus, the proposed network reduces the computational load involved in feature tracking algorithms and estimates muscle force from the global features of sparse ultrasound images.

Reliability of Measuring Geniohyoid Cross-Sectional Area with B-Mode Ultrasound.

B-mode ultrasound is a safe noninvasive procedure that has been used to characterize aspects of the oropharyngeal swallow. The submental suprahyoid muscles are often investigated with ultrasound because of their contributions to hyolaryngeal elevation. There are several techniques for positioning the ultrasound transducer in the coronal plane, however, there is limited research on how reliability of measurement of the cross-sectional area (CSA) of the geniohyoid differs across transducer placement technique. This study examined three methods of transducer placement in the coronal plane by two examiners to determine the reliability of measurement of CSA of the geniohyoid muscle. Forty healthy adults participated in the study. Each participant's geniohyoid muscles were imaged using B-mode ultrasound under three transducer placement conditions in the coronal plane by two examiners. Geniohyoid CSA was measured from each ultrasound image. A three-way mixed-methods ANOVA was used to determine whether there were significant differences in geniohyoid CSA among transducer position conditions, trials, and examiners. There were significant differences among the transducer placement conditions, indicating that each condition was measuring a different portion of the muscle. There were no significant differences among repeated trials nor between examiners within each method of transducer placement. All three conditions of transducer placement were reliable at measuring geniohyoid CSA across trials and examiners. This study emphasizes the need for consistency of placement, whichever method is selected. It also highlights the need for researchers to provide a precise description of methods for positioning the transducer so that placement is reproducible.

Characterization of cracking-healing cycle of asphalt mixture based on air-coupled second harmonic measurement using Duffing-van der pol oscillator

Second harmonic generation (SHG) technique using Rayleigh surface wave has been successfully attempted for the non-destruction evaluation of asphalt mixture during the self-healing process. The air-coupled transducer placement is desirable for the convenient implementation of SHG for the large-scale detection. Nevertheless, the pronounced attenuation of ultrasonic wave by air-coupled propagation will cause the second harmonic induced by microcracks to be barely detectable, particularly under the influence of inevitable noise. In this study, a novel approach by combining Duffing oscillator and van der pol equation is developed to identify and quantify the second harmonic in noise-contained signals based on the phase trajectory and periodic trajectory area exponent. The multi-physics finite element model is first established to simulate the air-asphalt propagation of Rayleigh waves, and proof-of-concept numerical simulations are carried out to estimate the second harmonic amplitude of noise-contaminated signals. The air-coupled SHG experiments are conducted, and the approach of the Duffing-van der pol oscillator is applied to extract the second harmonic in experimental data, and the self-healing behavior of asphalt mixture is analyzed through the variation of the nonlinear parameter of SHG measurements. The results indicate that the contactless SHG method combined with the Duffing-van der pol oscillator can effectively realize the convenient and reliable estimation of the nonlinear ultrasonic signal during the cycle of asphalt deterioration and healing, which is important for the property characterization of asphalt mixture considering its high attenuation to the ultrasonic waves.

Active cancellation of oblique noise entering a window

Environmental noise propagating through an open window may be cancelled by a sparse array of transducers placed in the window frame. This approach towards global noise cancellation mitigates noise pollution at its source while retaining the light and ventilation received from an open window. Heretofore the array’s performance has been studied with a normally incident noise source; however, oblique noise sources must be considered to fully illustrate the array’s viability as a commercial product. Analytical and finite element models were used to perdict the array’s global noise cancellation capabilities with regards to oblique noise sources, and these results were verified via experimental implementation. Flaws inherent to the current array, including cross bar vibrations and nonoptimal transducer placement, will be discussed along with how they will be circumvented in a future array iteration.

Prospective personalized planning of transcranial ultrasound transducer placement: A fast and heuristic tool

Prospective personalized planning of transcranial ultrasound transducer placement: A fast and heuristic tool

Investigating the relationship between quantitative-based ultrasound and MRI estimations of rotator cuff fatty infiltration.

Fatty infiltration (FI) of the rotator cuff has important clinical implications. Quantitatively estimating FI using ultrasound (US) has considerable benefits for assessing FI in a non-invasive, accessible manner. This research investigated whether FI of the supraspinatus (SS) and infraspinatus (IS), estimated using US was related to intramuscular fat fractions measured from magnetic resonance images (MRI). Data from 12 healthy young adult participants were used for analysis. US images of the SS and IS were captured using multiple transducer placement techniques from which echogenicity of the muscle region was quantified. Shoulder MRI were captured from which SS and IS were manually segmented and intramuscular fat fractions calculated. Six upper limb strength exertions were performed, resisted by a hand dynamometer. IS and SS echogenicity explained a significant amount of variance in MRI fat fractions for certain body positions and transducer techniques. Echogenicity agreement was higher for IS than SS. Significant relationships were identified between strength exertions and both echogenicity and MRI muscle volume, but not MRI fat fraction. This research provides preliminary evidence showing that quantitative-based US methods can be used to estimate MRI calculated fat fractions for the rotator cuff.

Acoustic micro‐beam vortex generator for flow actuation inside droplets

AbstractControlling acoustic streaming inside a droplet has excellent potential for enabling fluid and particle operations such as mixing, separation, and aggregation in various applications. Most concepts for generating surface acoustic waves are based on the placement of an interdigitated transducer at the side of a droplet, thus externally acting on the droplet. In this case, the flow structure inside the droplet is controlled by the relatively large scale of the interdigitated transducer compared to the droplet, thus limiting the local control of the flow. One possibility to overcome this drawback is to reduce the size of the actuator such that a highly focused ultrasound transducer can induce localized acoustic streaming in space. Here, we introduce a micro‐spiral interdigitated transducer smaller than a droplet size that can generate micro‐size vortices inside the droplet. This step enables a new way of controlling the flow inside the droplet, facilitating mixing, separation, aggregation, and patterning of particles. We study the characteristics of the acoustic streaming and the potential application of the flow for the separation and patterning of particles. The simplicity of the concept provides in‐droplet particle manipulation toolsets for many applications such as biosensing, microbiology, and point‐of‐care devices.

A novel coupling qualityindex to estimate the coupling efficiency in Vibrant Soundbridge.

The objective-based methods for intraoperative monitoring have been suggested to assess the coupling and the outcomes of Vibrant Soundbridge (VSB). Although several techniques were proposed, they have not been widely adopted due to their complexity and invasiveness. This study aimed to investigate the accuracy of a new coupling quality index using an intraoperative ABRthreshold via AcoustiAP and its correlation with the perioperative measures. This is a prospective study conducted at a tertiary center. The medical records were retrieved for all patients who underwent VSB implantation and had an intraoperative objective assessment for the coupling efficiency. AcoustiAP was used to evaluate the intraoperative ABR thresholds, which were assessed directly after the floating mass transducer (FMT) placement using acoustic CE-Chirp signals. The Vibrogram was used for the postoperative audiological evaluation. A new coupling quality index was calculated based on the intraoperative ABR thresholds. Ten patients were eligible for the present study. The ABR thresholds for good coupling ranged from 35 to 60 dBnHL. The loose coupling thresholds ranged considerably from 40 to 100 dBnHL. Overall, the median intraoperative ABR threshold at good coupling was 42.5 (40-60) dBnHL and 60 (40-100) dBnHL at loose coupling. The analysis showed that there was a significant change in the coupling quality index at the good and loose coupling points (24.3 ± 14 vs 38.8 ± 18.2, respectively, p < 0.001). At a cut-off value of 22.6dB, the coupling quality index had a sensitivity of 70% and specificity of 90% for discriminating good and loose coupling. This study provides evidence for the utility of intraoperative ABR measurements in predicting the coupling efficiency in patients with VSB. Our results showed that the coupling quality index had an acceptable accuracy in discriminating betweengood and poor coupling, which can help clinicians optimize the fitting process for individuals and may ultimately lead to improved patient outcomes.

Real-Time Acoustic Simulation Framework for tFUS: A Feasibility Study Using Navigation System

Transcranial focused ultrasound (tFUS), in which acoustic energy is focused on a small region in the brain through the skull, is a non-invasive therapeutic method with high spatial resolution and depth penetration. Image-guided navigation has been widely utilized to visualize the location of acoustic focus in the cranial cavity. However, this system is often inaccurate because of the significant aberrations caused by the skull. Therefore, acoustic simulations using a numerical solver have been widely adopted to compensate for this inaccuracy. Although the simulation can predict the intracranial acoustic pressure field, real-time application during tFUS treatment is almost impossible due to the high computational cost. In this study, we propose a neural network-based real-time acoustic simulation framework and test its feasibility by implementing a simulation-guided navigation (SGN) system. Real-time acoustic simulation is performed using a 3D conditional generative adversarial network (3D-cGAN) model featuring residual blocks and multiple loss functions. This network was trained by the conventional numerical acoustic simulation program (i.e., k-Wave). The SGN system is then implemented by integrating real-time acoustic simulation with a conventional image-guided navigation system. The proposed system can provide simulation results with a frame rate of 5 Hz (i.e., about 0.2 s), including all processing times. In numerical validation (3D-cGAN vs. k-Wave), the average peak intracranial pressure error was 6.8 ± 5.5%, and the average acoustic focus position error was 5.3 ± 7.7 mm. In experimental validation using a skull phantom (3D-cGAN vs. actual measurement), the average peak intracranial pressure error was 4.5%, and the average acoustic focus position error was 6.6 mm. These results demonstrate that the SGN system can predict the intracranial acoustic field according to transducer placement in real-time.

Accuracy of intra-arterial line transducer levelling practice in a general intensive care unit

BackgroundThe intra-arterial line is a common device intervention used in the intensive care environment to provide continuous blood pressure measurement. The transducer line is levelled to the patient's phlebostatic axis to provide accurate measurements. AimThe aim of this study was to investigate registered nurses' accuracy at levelling the transducer to the correct anatomical position using visual judgement, compared to one done using a laser level. MethodsPatient transducers were levelled by visual judgement and then by using a laser level. Time and mean arterial pressure (MAP) were recorded with each measurement along with any difference in transducer level between the two methods and subsequent changes in inotrope administration. ResultsA total of 577 MAP measurements were recorded from 178 patients; 70% of observations had a difference in transducer level, 30% of the time the inotrope rate was increased and 18% of the time the inotrope rate was reduced. The prevalence of clinically significant observations with an absolute difference of 50 mm or more in transducer placement was 25%. The mean difference in MAP measurements when a cut-off of 64 mmHg or more for laser was applied to the data was 0.22 (95% confidence interval: −0.14, 0.58, n = 513, p = 0.23), and for a cut-off of less than 64 for laser, a larger mean difference of 4.36 (95% confidence interval: 3.75, 5.28], n = 64, p < 0.001) was observed. ConclusionsTransducers were unable to be accurately levelled for haemodynamic monitoring using visual means alone. Over the range of patient MAP values examined, 25% of all observations had a clinically significant absolute difference of 50 mm or more in the transducer level position between the two methods. The visual method became increasingly inaccurate and unreliable at low MAP levels requiring medical intervention.