Magnitude Of Backscatter Research Articles

Detection of molecular backscattering with a tapered fiber amplifier based coherent heterodyne lidar

Fiber based coherent heterodyne lidars are highly valued and robust tools especially in sensing of wind speed and turbulence in the atmosphere. The magnitude of aerosol backscattering is also possible to be analysed from the data. However, the aerosol backscattering values cannot be calibrated without the data of molecular backscattering reference, which has not been available earlier due to power and bandwidth limitations. We present the detection of aerosol and molecular backscattering simultaneously with a fiber based coherent lidar instrument utilising a tapered fiber amplifier that yields to a pulse peak power of 1.9 kW at the wavelength of 1053 nm. Further, our receiver bandwidth of 1.5 GHz enables the spectral analysis of aerosol and molecular scattering spectra, which are recorded and analysed for multiple altitudes up to 1 km. The results demonstrate the potential of coherent heterodyne lidars to extend their capabilities toward backscattering and extinction analysis.

Melt pond detection on landfast sea ice using dual co-polarized Ku-band backscatter

The onset of melt ponds on landfast first-year and multiyear sea ice is detected using dual co-polarized Ku-band spaceborne scatterometer data. Twenty-nine locations in the Canadian Arctic Archipelago are used to develop and test the methodology. The daily ScatSat-1 sigma-nought backscatter composite product with a spatial resolution of 2.216 km is used. Vertical (VV) and horizontal (HH) polarizations of these data are used to derive the co-polarized ratio (VV/HH). An increase in VV/HH is associated with an increase in melt pond fraction on the sea ice. This occurs because there is a larger increase in resonant Bragg scattering for VV than for HH when melt pond surfaces exhibit wind-generated capillary waves. VV backscatter magnitude is evaluated in time series using a peak-finding methodology to initiate detection of melt ponds with VV/HH. The peak-finding is based on geophysical controls on backscatter from snow-covered sea ice during the melt season. Daily time-series data from ScatSat-1 are used in conjunction with ERA-5 reanalysis data (2-m air temperature and wind) and a semi-empirical snowmelt model. Air temperature data are used to identify snow melt onset and to force the snowmelt model. Wind data are used to evaluate if the wind speed is sufficient for capillary wave formation. The NSCAT-4DS geophysical model function is used to model Ku-band backscatter from water, which is then used in a sea ice mixture model to simulate the VV/HH magnitude for a range of pond fractions and wind speeds. The potential for detecting pond onset is evaluated in relation to the noise inherent in the ScatSat-1 VV/HH sea ice measurements, which is found to be approximately 0.16 dB. When the melt pond fraction is sufficiently large to cause VV/HH to exceed the noise, pond onset is detected. Cloud-free Sentinel-2 optical satellite imagery is used for validation; specifically, the near-infrared albedo. We find an overall mean bias of −0.5 days, and an absolute deviation of 1.4 days, when comparing our method to a near-infrared method for detecting pond onset. The mean biases (absolute deviations) for first-year and multiyear sea ice are −0.3 (1.5) and −0.8 (1.2) days, respectively. Results show that the temporal resolution, spatial resolution, and efficacy of this method can provide robust sea ice melt pond onset timing for landfast sea ice regions of the Arctic.

Influence of flow structures and combustion on cross-scale turbulent kinetic energy transfer in premixed swirl flames.

This paper experimentally analyzes the simultaneous influence of combustion and large-scale vortex structures on the transfer of kinetic energy across scales around the laminar flame thickness δL0 in a turbulent premixed swirl flame and a non-reacting swirl flow. High-resolution tomographic particle image velocimetry and formaldehyde planar laser induced fluorescence measurements are used to obtain 3D velocity fields and estimates of the progress variable and density fields. The kinetic energy transfer across a filter scale of Δ=1.5δL0 was then quantified using physical space analysis. Coherent flow structures were identified using the swirling strength and proper orthogonal decomposition was used to identify the dominant periodic flow structure. While non-reacting regions of the flow show mean down-scale energy transfer (forward-scatter), mean back-scatter is observed internal to the flame. Importantly, the back-scatter magnitude in the flame increases in regions undergoing flame/vortex interaction. That is, the mean back-scatter magnitude at locations simultaneously inside the flame and a large-scale coherent vortex is higher than regions in the flame and not in a vortex, with the mean back-scatter magnitude increasing with the swirling strength. This increased back-scatter may be due to locally higher heat release rates in locations of flame/vortex interaction. Overall, the results demonstrate the importance of kinetic energy back-scatter at scales around the flame thickness and the complicated relationship between back-scatter and local flame/flow structure; these results should be considered when modeling turbulence in flames.

Observations from C-Band SAR Fully Polarimetric Parameters of Mobile Sea Ice Based on Radar Scattering Mechanisms to Support Operational Sea Ice Monitoring

Fully polarimetric (FP) SAR systems offer parameters that describe and quantify the scattering mechanisms from the surface cover. These are usually derived from decomposition of matrices derived from the original scattering matrix from observations at each pixel. Power from scattering mechanisms have potential for retrieval of sea ice information, which cannot be derived using traditional backscatter (magnitude or phase) measured by single- or dual-polarization SAR systems. This study investigates the potential of selected FP parameters that represent the power of three scattering mechanisms, in addition to the total power, in identifying ice types and surface features for operational use. Parameters were obtained from a set of 62 RADARSAT-2 Quad-pol data over Resolute Passage, central Arctic, during the period September-December 2017. A scattering-based color-composite scheme was developed. Analysis of the examined color images was supported by information from regional ice charts and SAR image interpretations from the Canadian Ice Service. Case studies are presented to demonstrate the potential of the proposed color-composite tool. Open water, new ice, multi-year ice and a few surface features including rafted, ridged and smooth/rough surfaces can be identified better in the color images. Physical interpretation of the relative power from the given scattering mechanisms is explained for the relevant ice types and surfaces.

Atlantic deepwater ecosystem observatory network: Patterns of acoustic backscatter and community structure of the U.S. Outer Continental Shelf

Three nodes in the Atlantic Deepwater Ecosystem Observatory Network (ADEON) network on the U.S. Mid- and South Atlantic Outer Continental Shelf (OCS) contain an upward looking, multi-frequency echosounder system. Data was collected from November 2017–December 2020 at these sites extending from the OCS waters of Virginia down to Florida. Along shelf backscatter comparisons were made for general scattering groups related to fish and zooplankton across time and latitude. Unique seasonal patterns were observed across sites both in terms of volume backscatter magnitude and community structure. Measurements made within this research program will serve as a baseline for pattern and trend analyses of acoustic backscatter related to ecosystem components of this traditionally under sampled, offshore region. Study concept, oversight, and funding were provided by BOEM under Contract No. M16PC00003, in partnership with ONR and NOAA. Funding for ship time was provided under separate contracts by ONR, Code 32.

Physical space analysis of cross-scale turbulent kinetic energy transfer in premixed swirl flames

Understanding the cross-scale kinetic energy transport in turbulent flames is critical for physically-accurate modeling. This paper presents an experimental analysis of cross-scale kinetic energy transport in turbulent premixed swirl flames at Karlovitz numbers between 10 and 20 via physical space filtering. High-resolution tomographic particle image velocimetry and formaldehyde planar laser induced fluorescence measurements are used to obtain 3D velocity fields, as well as estimates for the progress variable and density fields. Filtering these fields at scales in the range of the laminar flame thickness (0.9<Δ/δL0<2.2) allows the kinetic energy transfer across the filter scale to be quantified. Mean kinetic energy transfer from sub-filter scales to larger scales (i.e. back-scatter) occurs internal to the flame structure across the range of conditions studied, with the maximum back-scatter occurring towards the center of the flame. Compared to equivalent non-reacting cases, considerably more back-scatter occurred in the reacting flows across all cases studied. At lower Karlovitz number, the magnitude of the back-scatter monotonically increased with increasing filter scale. At higher Karlovitz number, the back-scatter magnitude saturated at filter scales around Δ/δL0≈1.8. A scaling is proposed that quantifies the relative significance of the swirl-induced pressure gradient relative to the flame-induced pressure gradient on the pressure-work source of kinetic energy, indicating that swirling flow can significantly affect the kinetic energy dynamics. Overall, the results demonstrate that combustion significantly impacts the cross-scale kinetic energy transfer at scales in the range of the laminar flame thickness for conditions and configurations of practical relevance. These conclusions have implications for LES modelling strategies, providing evidence that models should allow for up-scale energy transfer in the vicinity of the flame.

A comparison between Zooglider and shipboard net and acoustic mesozooplankton sensing systems

Abstract Some planktonic patches have markedly higher concentrations of organisms compared to ambient conditions and are &lt;5 m in thickness (i.e. thin layers). Conventional net sampling techniques are unable to resolve this vertical microstructure, while optical imaging systems can measure it for limited durations. Zooglider, an autonomous zooplankton-sensing glider, uses a low-power optical imaging system (Zoocam) to resolve mesozooplankton at a vertical scale of 5 cm while making concurrent physical and acoustic measurements (Zonar). In March 2017, Zooglider was compared with traditional nets (MOCNESS) and ship-based acoustics (Simrad EK80). Zoocam recorded significantly higher vertically integrated abundances of smaller copepods and appendicularians, and larger gelatinous predators and mineralized protists, but similar abundances of chaetognaths, euphausiids, and nauplii. Differences in concentrations and size-frequency distributions are attributable to net extrusion and preservation artifacts, suggesting advantages of in situ imaging of organisms by Zooglider. Zoocam detected much higher local concentrations of copepods and appendicularians (53 000 and 29 000 animals m−3, respectively) than were resolvable by nets. The EK80 and Zonar at 200 kHz agreed in relative magnitude and distribution of acoustic backscatter. The profiling capability of Zooglider allows for deeper high-frequency acoustic sampling than conventional ship-based acoustics.

Probabilistic Substrate Classification with Multispectral Acoustic Backscatter: A Comparison of Discriminative and Generative Models

We propose a probabilistic graphical model for discriminative substrate characterization, to support geological and biological habitat mapping in aquatic environments. The model, called a fully-connected conditional random field (CRF), is demonstrated using multispectral and monospectral acoustic backscatter from heterogeneous seafloors in Patricia Bay, British Columbia, and Bedford Basin, Nova Scotia. Unlike previously proposed discriminative algorithms, the CRF model considers both the relative backscatter magnitudes of different substrates and their relative proximities. The model therefore combines the statistical flexibility of a machine learning algorithm with an inherently spatial treatment of the substrate. The CRF model predicts substrates such that nearby locations with similar backscattering characteristics are likely to be in the same substrate class. The degree of allowable proximity and backscatter similarity are controlled by parameters that are learned from the data. CRF model results were evaluated against a popular generative model known as a Gaussian Mixture model (GMM) that doesn’t include spatial dependencies, only covariance between substrate backscattering response over different frequencies. Both models are used in conjunction with sparse bed observations/samples in a supervised classification. A detailed accuracy assessment, including a leave-one-out cross-validation analysis, was performed using both models. Using multispectral backscatter, the GMM model trained on 50% of the bed observations resulted in a 75% and 89% average accuracies in Patricia Bay and Bedford Basin, respectively. The same metrics for the CRF model were 78% and 95%. Further, the CRF model resulted in a 91% mean cross-validation accuracy across four substrate classes at Patricia Bay, and a 99.5% mean accuracy across three substrate classes at Bedford Basin, which suggest that the CRF model generalizes extremely well to new data. This analysis also showed that the CRF model was much less sensitive to the specific number and locations of bed observations than the generative model, owing to its ability to incorporate spatial autocorrelation in substrates. The CRF therefore may prove to be a powerful ‘spatially aware’ alternative to other discriminative classifiers.

Re-examining the effect of particle phase functions on the remote-sensing reflectance.

Even though it is well known that both the magnitude and detailed angular shape of scattering (phase function, PF), particularly in the backward angles, affect the color of the ocean, the current remote-sensing reflectance (Rrs) models typically account for the effect of its magnitude only through the backscattering coefficient (bb). Using 116 volume scattering function (VSF) measurements previously collected in three coastal waters around the U.S. and in the water of the North Atlantic Ocean, we re-examined the effect of particle PF on Rrs in four scenarios. In each scenario, the magnitude of particle backscattering (i.e., bbp) is known, but the knowledge on the angular shape of particle backscattering is assumed to increase from knowing nothing about the shape of particle PFs to partially knowing the particle backscattering ratio (Bp), the exact backscattering shape as defined by β˜p(γ≥90°) (particle VSF normalized by the particle total scattering coefficient), and the exact backscattering shape as defined by the χp factor (particle VSF normalized by the particle backscattering coefficient). At sun zenith angle=30°, the nadir-viewed Rrs would vary up to 65%, 35%, 20%, and 10%, respectively, as the constraints on the shape of particle backscattering become increasingly stringent from scenarios 1 to 4. In all four scenarios, the Rrs variations increase with both viewing and sun angles and are most prominent in the direction opposite the sun. Our results show a greater impact of the measured particle PFs on Rrs than previously found, mainly because our VSF data show a much greater variability in Bp, β˜p(γ≥90°), and χp than previously known. Among the uncertainties in Rrs due to the particle PFs, about 97% can be explained by χp, 90% by β˜p(γ≥90°), and 27% by Bp. The results indicate that the uncertainty in ocean color remote sensing can be significantly constrained by accounting for χp of the VSFs.

Ku-, X- and C-Band Microwave Backscatter Indices from Saline Snow Covers on Arctic First-Year Sea Ice

In this study, we inter-compared observed Ku-, X- and C-band microwave backscatter from saline 14 cm, 8 cm, and 4 cm snow covers on smooth first-year sea ice. A Ku-, X- and C-band surface-borne polarimetric microwave scatterometer system was used to measure fully-polarimetric backscatter from the three snow covers, near-coincident with corresponding in situ snow thermophysical measurements. The study investigated differences in co-polarized backscatter observations from the scatterometer system for all three frequencies, modeled penetration depths, utilized co-pol ratios, and introduced dual-frequency ratios to discriminate dominant polarization-dependent frequencies from these snow covers. Results demonstrate that the measured co-polarized backscatter magnitude increased with decreasing snow thickness for all three frequencies, owing to stronger gradients in snow salinity within thinner snow covers. The innovative dual-frequency ratios suggest greater sensitivity of Ku-band microwaves to snow grain size as snow thickness increases and X-band microwaves to snow salinity changes as snow thickness decreases. C-band demonstrated minimal sensitivity to changes in snow salinities. Our results demonstrate the influence of salinity associated dielectric loss, throughout all layers of the three snow covers, as the governing factor affecting microwave backscatter and penetration from all three frequencies. Our “plot-scale” observations using co-polarized backscatter, co-pol ratios and dual-frequency ratios suggest the future potential to up-scale our multi-frequency approach to a “satellite-scale” approach, towards effective development of snow geophysical and thermodynamic retrieval algorithms on smooth first-year sea ice.

Unifying Concepts of Statistical and Spectral Quantitative Ultrasound Techniques.

Quantitative ultrasound (QUS) techniques using radiofrequency (RF) backscattered signals have been used for tissue characterization of numerous organ systems. One approach is to use the magnitude and frequency dependence of backscatter echoes to quantify tissue structures. Another approach is to use first-order statistical properties of the echo envelope as a signature of the tissue microstructure. We propose a unification of these QUS concepts. For this purpose, a mixture of homodyned K-distributions is introduced to model the echo envelope, together with an estimation method and a physical interpretation of its parameters based on the echo signal spectrum. In particular, the total, coherent and diffuse signal powers related to the proposed mixture model are expressed explicitly in terms of the structure factor previously studied to describe the backscatter coefficient (BSC). Then, this approach is illustrated in the context of red blood cell (RBC) aggregation. It is experimentally shown that the total, coherent and diffuse signal powers are determined by a structural parameter of the spectral Structure Factor Size and Attenuation Estimator. A two-way repeated measures ANOVA test showed that attenuation (p-value of 0.077) and attenuation compensation (p-value of 0.527) had no significant effect on the diffuse to total power ratio. These results constitute a further step in understanding the physical meaning of first-order statistics of ultrasound images and their relations to QUS techniques. The proposed unifying concepts should be applicable to other biological tissues than blood considering that the structure factor can theoretically model any spatial distribution of scatterers.

Characterizing riverbed sediment using high-frequency acoustics: 2. Scattering signatures of Colorado River bed sediment in Marble and Grand Canyons

In this, the second of a pair of papers on the statistical signatures of riverbed sediment in high-frequency acoustic backscatter, spatially explicit maps of the stochastic geometries (length and amplitude scales) of backscatter are related to patches of riverbed surfaces composed of known sediment types, as determined by georeferenced underwater video observations. Statistics of backscatter magnitudes alone are found to be poor discriminators between sediment types. However, the variance of the power spectrum and the intercept and slope from a power law spectral form (termed the spectral strength and exponent, respectively) successfully discriminate between sediment types. A decision tree approach was able to classify spatially heterogeneous patches of homogeneous sands, gravels (and sand-gravel mixtures), and cobbles/boulders with 95, 88, and 91% accuracy, respectively. Application to sites outside the calibration and surveys made at calibration sites at different times were plausible based on observations from underwater video. Analysis of decision trees built with different training data sets suggested that the spectral exponent was consistently the most important variable in the classification. In the absence of theory concerning how spatially variable sediment surfaces scatter high-frequency sound, the primary advantage of this data-driven approach to classify bed sediment over alternatives is that spectral methods have well-understood properties and make no assumptions about the distributional form of the fluctuating component of backscatter over small spatial scales.

Biomass Estimation Using ALOS PALSAR for Identification of Lowland Forest Transition Ecosystem in Jambi Province

The accurate information derived from high accuracy of remote sensing imagery analyses coupled with field observation data are required to develop a sound forest management. The study is mainly emphasized on assessment of the capabilities of remote sensing imageries to identify ecosystem types within the transitional ecosystem. Since, the predominant transition ecosystems found within the study area were secondary forest, rubber jungle, rubber, oil palm plantation, and also other land cover such as mixed plantation and shrubs, therefore, the models developed were focused for those ecosystem types. Prior to any further analysis, this study was initiated to develop the biomass estimation model using 50 m resolution of ALOS PALSAR image in transition ecosystem, Jambi Province. Biomass models were developed by analyzing the relationship between backscatter magnitude and field biomass. Backscatter magnitude from 1 polarization images, namely HH, HV, and one additional band of ratio of HH/HV were analyzed simultaneously with field biomass. The best models established are AGB = 42,069 exp (0.510 HV) and AGB = 1,610 exp (-0.02 HV²) with R² of 52.3% and 50,8%, respectively. The models are then used to map out the biomass distribution within the transition ecosystem and to identify the factors affecting the magnitude of biomass content for all transition ecosystem types.

Numerical Simulations and Analysis of Wide-Band Range-Resolved HF Backscatter From Evolving Ocean-Like Surfaces

Low-grazing wide-band HF radar echoes from evolving ocean-like surfaces in 2-D space are simulated employing a first-principles boundary integral equation technique. The synthesized signals achieve range resolution of about 15 m and correspond to observations with a hypothetical narrow-beam system having a 10-MHz effective bandwidth. Range-time plots of backscatter magnitude appear to contain a pattern consistent with the long surface waves. The double Fourier transform of the signal magnitude or power in range and time reveals strong harmonics located along the dispersion curve of the propagating gravity waves. The effect is discernable due to the high range resolution employed and is not predicted by the first-order Small Perturbation Method (SPM) approximation. It is explained by considering the next, second order of the SPM under certain simplifying assumptions such as perfect surface conductivity (with the Norton attenuation factor set to 1). The derived analytical expression is then used to investigate the feasibility of the surface profile retrieval from such time-varying range-resolved HF backscatter (gathered in the course of the “numerical experiment” through the exact scattering simulations). For the case of perfectly conducting sea-like surface developed under 10-m/s wind conditions, the results are very encouraging. The approach is sensitive to the surface harmonics with wavelengths far exceeding the Bragg resonance scales of the HF band. Extending this type of analysis to cases with realistic finite conductivity and/or rougher surface (assuming that the second-order SPM is still valid) will require proper accounting for ground-wave propagation effects in perturbation expressions. The study offers a glimpse into ocean observation possibilities that the wide-band HF systems can provide if and when they become a reality.

Tu1594 Technical Aspects of Endoscopic Removal of Stents Placed for Benign Esophageal Diseases

Tu1594 Technical Aspects of Endoscopic Removal of Stents Placed for Benign Esophageal Diseases

Characterisation of polymer-shelled microbubbles in wall-less flow phantom using high-frequency ultrasound and video microscopy

A high frequency ultrasound pulse echo system and a video microscope were combined to investigate the relationship between backscatter from polymer shelled ultrasound contrast agents (UCAs) and their diameter. Individual UCAs (manufactured by Point Biomedical or Philips Research) were imaged while being sonicated with 40 MHz tone bursts. The backscatter magnitude produced by the Philips UCAs was proportional to UCA size, which is consistent with theoretically predicted behaviour of encapsulated microbubbles driven at frequencies above resonance. Despite being smaller, the Point UCAs produced a backscatter magnitude twice that of Philips UCAs, indicating that Point UCAs might behave quasi-resonantly when excited at 40 MHz.

Small-scale variability in suspended matter associated with the Connecticut River plume front

[1] We report high spatial resolution observations of optical proxies for suspended particles and dissolved matter measured at the boundary of the Connecticut River plume (CRP) in Long Island Sound (LIS) in April 2000 when river discharge was near the annual maximum. The magnitude of beam attenuation, cp, backscatter, bb, and absorption at short wavelengths indicated higher concentration of suspended particles and colored dissolved matter within the LIS relative to the adjacent CRP. The fractional backscatter from particles indicated relatively higher organic matter fraction within the LIS. An absorption feature centered at 429 nm (aPB), indicated the presence of pigmented heterotrophic bacteria unique to the LIS and the strongest signals were observed at locations closest to shore. The spectral slope of beam attenuation associated with particulate matter (γ) indicated the presence of relatively larger particle assemblages within the LIS. Strong linear relationships between γ and salinity were observed within the energetic CRP boundary region, within 30 m of the front location. Regression residuals indicated a shift to smaller particles and were greatest at the front and decreased with distance toward the plume interior with a length scale similar to previous reports of the kinetic energy dissipation rate. At the same time, the magnitude of cp and bb remained uniform. These results are consistent with the disruption of low fractal dimension particle assemblages due to enhanced turbulence and mixing. The residuals in γ were weakly correlated with salinity and aPB suggesting that aggregate disruption was primarily associated with entrained Long Island Sound water.

Estimating Urban Canopy Parameters Using Synthetic Aperture Radar Data

Abstract This paper introduces a remote sensing–based approach to rapidly derive urban morphological characteristics using radar satellite data. The approach is based on the expectation that the magnitude of the synthetic aperture radar (SAR) backscatter can be related to urban canopy parameters (UCPs) describing the height, density, and roughness of buildings, trees, and other objects in cities. This hypothesis was tested with full-feature terrain elevation and SAR datasets for the Houston, Texas, metropolitan area. The backscatter magnitude was found to vary as expected across the city with higher backscatter values in the downtown tall building district relative to adjacent residential and commercial areas. To demonstrate the concept of using radar backscatter to estimate UCPs, relationships were derived between SAR backscatter and mean height, plan area fraction, and frontal area index of roughness elements (e.g., buildings and trees). In addition, SAR backscatter relationships were derived with roughness lengths computed using morphometric approaches. In all cases, the derived relationships were found to provide estimates of UCPs acceptable for use in meteorological models. Further testing using data from the Salt Lake City, Utah, metropolitan area validated the relationships and identified key areas for improvement for future research, including SAR instrument view angle differences and buildings split between SAR pixels.

Monitoring Suspended Sediment Dynamics Using MBES

This technical note describes use of a multibeam echosounder (MBES) to quantify the dynamics of suspended sediment in a large open channel. A methodology is detailed that uses the backscatter magnitude from the MBES water-column data to adjust the magnitude of sonar returns for the various sonar settings, spatially and temporally average the data to account for the random nature of acoustic backscatter from the suspended sediment, and calibrate the processed data with direct samples. A case study of flow at the confluence of the Rio Parana and Rio Paraguay, Argentina, where there is a distinct turbidity difference along the mixing interface of the two flows, is used to demonstrate the unique capabilities of MBES to quantify sediment concentrations and dynamics within the water column.

An experimental attenuation plate to improve the dose distribution in intraoperative electron beam radiotherapy for breast cancer

Intraoperative electron beam radiotherapy (IOERT) is a technique in which a single-fraction high dose is intraoperatively delivered to subclinical tumour cells using an electron beam after breast-conserving surgery. In IOERT, an attenuation plate consisting of a pair of metal disks is commonly used to protect the normal tissues posterior to the breast. However, the dose in front of the plate is affected by backscatter, resulting in an unpredictable delivered dose to the tumour cells. In this study, an experimental attenuation plate, termed a shielding plate, was designed using Monte Carlo simulation, which significantly diminished the electron beam without introducing any backscatter radiation. The plate's performance was verified by measurements. It was made of two layers, a first layer (source side) of polymethyl methacrylate (PMMA) and a second layer of copper, which was selected from among other metals (aluminium, copper and lead) after testing for shielding capability and the range and magnitude of backscatter. The optimal thicknesses of the PMMA (0.71 cm) and copper (0.3 cm) layers were determined by changing their thicknesses during simulations. On the basis of these results, a shielding plate was prototyped and depth doses with and without the plate were measured by radiophotoluminescence glass dosimeters using a conventional stationary linear accelerator and a mobile linear accelerator dedicated for IOERT. The trial shielding plate functioned as intended, indicating its applicability in clinical practice.