Human Phantom Research Articles

IS2aR, a computational tool to transform voxelized reference phantoms into patient-specific whole-body virtual CTs for peripheral dose estimation

BackgroundThe risk of radiogenic cancer induction due to radiotherapy depends on the dose received by the patient's organs. Knowing the position of all organs is needed to assess this dose in a personalized way. However, radiotherapy planning computed tomography (pCT) scans contain truncated patient anatomy, limiting personalized dose evaluation. PurposeTo develop a simple and freely available computational tool that adapts an ICRP reference computational phantom to generate a patient-specific whole-body CT for peripheral dose computations. MethodsVarious bone-segmentation methods were explored onto fifteen pCTs, and the one with the highest Sørensen-Dice coefficient was implemented. The reference phantom is registered to the pCT, obtaining a registration transform matrix, which is then applied to create the whole-body virtual CT. Additional validation involved a comparison of absorbed doses to organs delineated on both the pCT and the virtual CT. ResultsA dedicated graphical user interface was designed and implemented to house the developed functions for i) selecting a registration region on which automatic bone segmentation and rigid registration will occur, ii) displaying the results of these processes under selectable views, and iii) exporting the final patient-specific whole-body CT. This software was termed IS2aR. The tested whole-body virtual CT generated by IS2aR fulfilled our requirements. ConclusionsIS2aR is a user-friendly computational software to create a personalized whole-body CT containing the original structures in the reference phantom. The personalized dose deposited in peripheral organs can be estimated further to assess second cancer induction risk in epidemiological studies.

A Computer‐Aided Teleoperation System for Intuitively Controlling the Behavior of a Magnetic Millirobot within a Stomach Phantom

Untethered magnetic millirobots with a characteristic length of a few millimeters can be wirelessly controlled. They exhibit promising potential in a wide variety of applications, particularly for tasks in clinic workspaces. However, magnetically controlling these robots is counter‐intuitive and requires a steep learning curve, hindering their wide adoption. Herein, a computer‐aided teleoperation platform is developed to operate a soft millirobot, with its feedback control being conducted behind‐the‐scenes, bridging the user's inputs directly with the millirobot's actions to offer an intuitive control. This system enables untrained users to conveniently control the position and actions of the millirobot inside a human stomach phantom by pointing‐and‐clicking on a real‐time video monitor or using a keyboard. The platform automatically materializes the user's instructions by maneuvering a robotic arm with a tip‐mounted magnet to exert a magnetic field to induce the desired response from the millirobot. Experiments show that the system allows the user to intuitively operate the millirobot and deliver its cargo without splitting their attention to monitor the workspace or to calculate the constantly changing control parameters. This platform can lower the barrier for healthcare practitioners without engineering expertise to adopt miniature robotic systems into their workflow and realize these systems’ promising potential.

A dose calculation algorithm for boron neutron capture therapy using convolution/superposition method

The convolution/superposition (C/S) method originally designed for photon dose calculation was first applied for developing a treatment planning system for boron neutron capture therapy. The original concept of TEGMA (total energy generated per unit mass) was proposed to represent distinctive dose components from neutron reactions with the elements in the patient's tissue. First, neutron fluence distributions in a homogeneous brain phantom irradiated with an energy-groupwise pencil beam of 2.5 × 2.5 mm2 were calculated using the MCNP6.2 code. Then, a library of energy-groupwise TEGMA and KERMA were generated and stored in the developed C/S code. As a benchmark, dose distributions in a cuboid phantom and a human head phantom were calculated using the developed C/S and PHITS Monte Carlo codes. A neutron beam having a continuous epithermal spectrum and a square field of 22.5 × 22.5 mm2 or a circle field of 22.5 mm in diameter was assumed to be incident on the phantoms. The human head phantom was created by the pre-processing including the voxelization and transformation of test DICOM CT images. The differences in boron doses between C/S and MC ranged from 2% to 6%. In nitrogen doses, the differences were from 4% to 9%. A large discrepancy observed in hydrogen lateral dose profiles could be explained by the differences in cross-section data and recoil-proton transport algorithms of MCNP6.2 and PHITS. With isodose curves normalized at the center of the tumor in the human head phantom, they were almost identical in the range of 60%–110% for both cases. The C/S have underestimated the backscattering neutron and showed a larger absorbed dose gradient around 40% region. The calculation time of C/S using Intel i7-10700 processor was less than 1 min for both phantoms. The calculation time of PHITS using three Intel Xeon E5-2640 v4 processors was 15.5 min for the cuboid phantom and ∼380 min for the human head phantom. The proposed algorithm has the advantages of high speed while promising fair accuracy in BNCT dose calculations.

Technical note: Optimization functions for re-irradiation treatment planning.

Although re-irradiation is increasingly used in clinical practice, almost no dedicated planning software exists. Standard dose-based optimization functions were adjusted for re-irradiation planning using accumulated equivalent dose in 2-Gy fractions (EQD2) with rigid or deformable dose mapping, tissue-specific α/β, treatment-specific recovery coefficients, and voxelwise adjusted EQD2 penalization levels based on the estimated previously delivered EQD2 (EQD2deliv ). To demonstrate proof-of-concept, 35Gy in 5 fractions was planned to a fictitious spherical relapse planning target volume (PTV) in three separate locations following previous prostate treatment on a virtual human phantom. The PTV locations represented one repeated irradiation scenario and two re-irradiation scenarios. For each scenario, three re-planning strategies with identical PTV dose-functions but various organ at risk (OAR) EQD2-functions was used: 1) reRTregular : Regular functions with fixed EQD2 penalization levels larger than EQD2deliv for all OAR voxels. 2) reRTreduce : As reRTregular , but with lower fixed EQD2 penalization levels aiming to reduce OAR EQD2. 3) reRTvoxelwise : As reRTregular and reRTreduce , but with voxelwise adjusted EQD2 penalization levels based on EQD2deliv . PTV near-minimum and near-maximum dose (D98% /D2% ), homogeneity index (HI), conformity index (CI) and accumulated OAR EQD2 (α/β=3Gy) were evaluated. For the repeated irradiation scenario, all strategies resulted in similar dose distributions. For the re-irradiation scenarios, reRTreduce and reRTvoxelwise reduced accumulated average and near-maximum EQD2 by ˜1-10 Gy for all relevant OARs compared to reRTregular . The reduced OAR doses for reRTreduce came at the cost of distorted dose distributions with D98% = 92.3%, HI = 12.0%, CI = 73.7% and normal tissue hot spots ≥150% for the most complex scenario, while reRTregular (D98% = 98.1%, HI = 3.2%, CI = 94.2%) and reRTvoxelwise (D98% = 96.9%, HI = 6.1%, CI = 93.7%) fulfilled PTV coverage without hot spots. The proposed re-irradiation-specific EQD2-based optimization functions introduce novel planning possibilities with flexible options to guide the trade-off between target coverage and OAR sparing with voxelwise adapted penalization levels based on EQD2deliv .

131I dose coefficients for a reference population using age-specific models

Age-specific dose coefficients are required to assess internal exposure to the general public. This study utilizes reference age-specific biokinetic models of iodine to estimate the total number of nuclear disintegrations ã(r S,τ) occurring in source regions (r S) during the commitment time (τ). Age-specific S values are estimated for 35 target regions due to 131I present in 22 r S using data from 10 paediatric reference computational phantoms (representing five ages for both sexes) published recently by the International Commission of Radiation Protection (ICRP). Monte Carlo transport simulations are performed in FLUKA code. The estimated ã(r S,τ) and S values are then used to compute the committed tissue equivalent dose HT(τ) for 27 radiosensitive tissues and dose coefficients e(τ) for all five ages due to inhalation and ingestion of 131I. The derived ã(r S,τ) values in the thyroid source are observed to increase with age due to the increased retention of iodine in the thyroid. S values are found to decrease with age, mainly due to an increase in target masses. Generally, HT(τ) values are observed to decrease with age, indicating the predominant behaviour of S values over ã(r S,τ). On average, ingestion dose coefficients are 63% higher than for inhalation in all ages. The maximum contribution to dose coefficients is from the thyroid, accounting for 96% in the case of newborns and 98%–99% for all other ages. Furthermore, the estimated e(τ) values for the reference population are observed to be lower than previously published reference values from the ICRP. The estimated S, HT(τ) and e(τ) values can be used to improve estimations of internal doses to organs/whole body for members of the public in cases of 131I exposure. The estimated dose coefficients can also be interpolated for other ages to accurately evaluate the doses received by the general public during 131I therapy or during a radiological emergency.

Spin Coated Multi‐Walled Carbon Nanotube Patch Antenna for Breast Cancer Detection

AbstractEarly detection of breast cancer can be a life‐saving measure for many patients. The inaccessibility of X‐rays, magnetic resonance imaging (MRI), and other medical facilities in many resource‐constrained areas hinders the early detection of breast cancer. In this paper, the use of a rectangular patch antenna for breast cancer detection is proposed by using multiwall carbon nanotubes (MWCNTs) as patch material. The proposed antenna is designed by CST software which is (30 × 40 × 1.66) mm in dimension. A breast model is designed including tumor and cancerous tumors by specific tissue properties for observing the antenna performance in different cases. In free space, the return loss of the designed antenna is observed at −33.414 dB. Moreover, the S11 is examined in a normal breast, a breast including a normal tumor, and a breast including a cancerous tumor is −32.641 dB, −34.94 dB, and −35.22 dB respectively. It can be utilized on a human body phantom model due to its adaptability and reduced radiation properties. The proposed antenna is miniature in size, cost‐effective, easily portable, and eco‐friendly. It can be used as a first screening tool for breast cancer patients, particularly in resource‐constrained regions.

Development of Respiratory Tract Organs for ICRP Pediatric Mesh-type Reference Computational Phantoms.

As part of the activities of the International Commission on Radiological Protection (ICRP) Task Group 103, the present study developed a new set of respiratory tract organs consisting of the extrathoracic, bronchial, bronchiolar, and alveolar-interstitial regions for newborn, 1-, 5-, 10-, and 15-y-old males and females for use in pediatric mesh-type reference computational phantoms. The developed respiratory tract organs, while preserving the original topologies of those of the pediatric voxel-type reference computational phantoms of ICRP Publication 143, have improved anatomy and detailed structure and also include μm-thick target and source regions prescribed in ICRP Publication 66. The dosimetric impact of the developed respiratory tract organs was investigated by calculating the specific absorbed fraction for internal electron exposures, which were then compared with the ICRP Task Group 96 values. The results showed that except for the alveolar-interstitial region as a source region, the pediatric mesh phantoms showed larger specific absorbed fractions than the Task Group 96 values. The maximum difference was a factor of ~3.5 for the extrathoracic-2 basal cell and surface as target and source regions, respectively. These results reflect the differences in the target masses and geometry caused by the anatomical enhancement of the pediatric mesh phantoms. For the alveolar-interstitial region as a source region, the pediatric mesh phantoms showed larger values for low energy ranges and lower values with increasing energies, owing to the differences in the size and shape of the alveolar-interstitial region.

Numerical model of human head phantom to ensure dosimetry of dose components for boron neutron capture therapy.

Extremely important aspects of the boron neutron capture therapy are, first of all, administering to the patient a boron compound that selectively reaches the neoplastic cells, and in the second step, the verification of the irradiation process. This paper focuses on the latter aspect, which is the detailed dosimetry of the processes occurring after the reaction of thermal neutrons with the boron-10 isotope. The results of computer simulations with the use of a new type of human head phantom filled with a polymer dosimetric gel will be presented in this article.

Radiation Protection Considerations for Cancer Patients with End-stage Renal Disease Receiving 131 I Treatment.

Differentiated thyroid cancer (DTC) is commonly treated first with a partial or complete thyroidectomy, followed by radioiodine (RAI) ablative therapy to eliminate remaining cancer cells. In such treatments, physical decay and urinary excretion are the primary means of 131 I. As such, patients with impaired urinary ability clearance, such as patients with end-stage renal disease (ESRD) whose urinary ability is impaired by dysfunction, can retain abnormally high activities of RAI, posing a concern to both the patient and those with whom the patient interacts. Additionally, ESRD patients are commonly administered dialysis therapy, wherein their blood is externally cycled through a dialyzer (hemodialysis) or filtered by instilling a dialysate fluid into the peritoneum (peritoneal dialysis) to filter uremic toxins from their blood that accumulate due to kidney dysfunction. These factors make determining release and dosing for ESRD patients receiving RAI therapy dependent on a plurality of variables. An evaluation of the current patient release guidelines, as given in US Nuclear Regulatory Commission (US NRC) Regulatory Guide 8.39 Rev. 1 for ESRD patients receiving RAI, has yet to be addressed. In this study, a biokinetic model for 131 I in ESRD patients receiving dialysis has been developed, improving on traditional two-compartment models, reflective of kinetics from multi-compartment models with updated transfer coefficients modified to reflect the different physiological functions of compartments. This updated biokinetic model was integrated with Monte Carlo radiation transport calculations using stylized computational hermaphroditic phantoms to calculate dose rate coefficients in exposure scenarios and compared with those of the point source models of NRC Reg Guide 8.39 Rev. 1 (and the proposed verbiage in Rev. 2). Results demonstrated that the baseline models of Rev. 1 and Rev. 2 overestimated the effective dose rate to an exposed individual for the majority of time post-administration, where both models overestimated the total dose to the maximally exposed individual. However, the application of several patient-specific modifying factors to the Rev. 2 model resulted in an overestimation by only a factor of 1.25, and in general, the results produced with the patient-specific modifications provide improved convergence with the dose rate coefficients computed in this study for ESRD patients.

Quality assurance for mixed electron-photon beam radiation therapy using treatment log files and MapCHECK.

Mixed photon-electron beam radiotherapy (MBRT) is a technique that combines the use of both photons and electrons in one single treatment plan to exploit their advantageous and complimentary characteristics. Compared to other photon treatment modalities, it has been shown that the MBRT technique contributes to better target coverage and organ-at-risk (OAR) sparing. However, the use of combined photons and electrons in one delivery makes the technique more complex and a well-established quality assurance (QA) protocol for MBRT isessential. To investigate the feasibility of using MapCHECK and log file-dose reconstruction for MBRT plan verification and to recommend a patient-specific quality assurance (PSQA) protocol forMBRT. MBRT plans were robustly optimized for five soft-tissue sarcoma (STS) patients. Each plan comprised step-and-shoot deliveries of a six MV photon beam and a combination of five electron beam energies at an SAD of 100 cm. The plans were delivered to the MapCHECK device with collapsed gantry angle and the 2D dose distributions at the detector depth were measured. To simulate the expected dose distribution delivered to the MapCHECK, a MapCHECK computational phantom was modeled in EGSnrc based on vendor-supplied blueprint information. The dose to the detectors in the model was scored using the DOSXYZnrc user code. The agreement between the measured and the simulated dose distribution was evaluated using 2D gamma analysis with a gamma criterion of 3%/2 mm and a low dose threshold of 10%. One of the plans was selected and delivered with a rotating gantry angle for trajectory log file collection. To evaluate the potential interlinac and intralinac differences, the plan was delivered repeatedly on three linacs. From the collected log files, delivery parameters were retrieved to recalculate the 3D dose distributions in the patient's anatomy with DOSXYZnrc. The recalculated mean dose to the clinical target volume (CTV) and OARs from all deliveries were computed and compared with the planned dose in terms of percentage difference. To validate the accuracy of log file-based QA, the log file-recalculated dose was also compared with filmmeasurement. The agreement of the total dose distribution between the MapCHECK measurement and simulation showed gamma passing rates of above 97% for all five MBRT plans. In the log file-dose recalculation, the difference between the recalculated and the planned dose to the CTV and OARs was below 1% for all deliveries. No significant inter- or intralinac differences were observed. The log file-dose had a gamma passing rate of 98.6% compared to filmmeasurement. Both the MapCHECK measurements and log file-dose recalculations showed excellent agreement with the expected dose distribution. This study demonstrates the potential of using MapCHECK and log files as MBRT QAtools.

Development of Population-Based Pediatric Computational Phantoms for Radiotherapy Applications.

Age-specific pediatric computational phantoms are used in radiotherapy (RT) for quality assurance and for reconstruction of historical RT doses (within others). Phantoms are typically developed from healthy patients and may not effectively represent those with cancer due to pathology and/or treatment effects. This study evaluated a set of population-based pediatric computational phantoms developed in-house in terms of anatomical plausibility. Planning CTs and contours from historical craniospinal irradiation (CSI) patients (n = 74, median age 7y, range: 1-17y) were used to generate and evaluate a set of in-house age-specific population-based RT phantoms (RT-P). The RT-P were generated by combining a sub-set of clinical CTs and contours through groupwise deformable image registration, generating average models of CSI sub-populations (n = 74, median age 7y, range: 3-14y). Models were then compared against clinical data and two libraries of phantoms representing healthy populations: the International Commission on Radiological Protection (ICRP) pediatric reference computational phantoms (n = 8, median age 8y, range: 1-15y) and a variety of default 4D extended cardiac torso (XCAT) phantoms (n = 75, median age 9y, range: 1-18y). Variation between organ volumes for the different datasets was assessed through a linear fit of organ volume with age, reporting the slope (∑) of each fit [y-1]. Average difference between the volume datapoints and the linear fit for clinical data (Δ) [%] were also reported. This allowed for comparisons of the RT-P to clinical and reference data in terms of organ volumes across developmental stages. The table shows 9 of the 19 investigated organs. The ∑ reported for RT-P models were of similar magnitude as the clinical data and other phantoms, effectively modelling changes with age. The greatest and least ∑ were reported from lungs and thyroid respectively, in agreement with expected relative sizes between organs. Larger values for Δ were likely due to differences in organ filling and segmentation strategy between datasets, limitations of RT-P methodology, and/or anatomical differences between healthy and cancer populations. The RT-P models show promise in representing the RT cohort that may benefit from specialized anatomical phantoms. Further work is needed to address the limitations of the current methodology and its applicability to other RT cohorts.

Functional analysis in the body environment for a circularly polarized hybrid reconfigurable textile antenna

This paper presents the functional analysis of a hybrid reconfigurable circularly polarized (CP) textile antenna in different on-body environments. The Tai-Chi sign inspires the current textile antenna design, where the primary radiator and ground elements are sickle-shaped structures. Hybrid reconfigurability was achieved by successfully operating two RF PIN-Diodes in the basal ground plane’s elliptical and rectangular structures. Thus, four switching states are attained by operating the textenna at 3.5, 4.5 and 5.4 GHz in the S1. 4.39 and 5.8 GHz in S2, 5 and 5.9 GHz in S3 and 2.4, 4.3, 5.8, and 9.4 GHz in S4 state. The reconfigurable textenna was devised to function on the human body. Its functional behavior in proximity to the human body was rigorously validated through testing involving bending at various vertical and horizontal angles. Additionally, a Specific Absorption Rate (SAR) analysis was conducted using a three-layered human phantom. The results revealed that the maximum SAR value is below 1.6 W Kg−1 for 1 gram of tissue and 2 W kg−1 for 10 grams of tissue. These findings establish the safe operational parameters for the proposed model. The developed antenna functionalities were also tested in other circumstances like body sweating environment and interaction with body fluids (Blood, Plasma, SBF and DMEM). In these body fluid conditions, a peak gain of 4.88 dBi at S1, 6.97 dBi at S2, 7.99 dBi at S3, and 4.13 dBi at S4, was observed while interacting with Plasma, and the measured efficiency in the above configuration is between 77%–79%. The textenna durability analysis was measured using an electrochemical workstation while interacting with different body fluids. All these results confessed the applicability of the developed antennas for on-body wireless communication applications in different on-body conditions.

Dose Optimization Using a Deep Learning Tool in Various CT Protocols for Urolithiasis: A Physical Human Phantom Study.

Background and Objectives: We attempted to determine the optimal radiation dose to maintain image quality using a deep learning application in a physical human phantom. Materials and Methods: Three 5 × 5 × 5 mm3 uric acid stones were placed in a physical human phantom in various locations. Three tube voltages (120, 100, and 80 kV) and four current-time products (100, 70, 30, and 15 mAs) were implemented in 12 scans. Each scan was reconstructed with filtered back projection (FBP), statistical iterative reconstruction (IR, iDose), and knowledge-based iterative model reconstruction (IMR). By applying deep learning to each image, we took 12 more scans. Objective image assessments were calculated using the standard deviation of the Hounsfield unit (HU). Subjective image assessments were performed by one radiologist and one urologist. Two radiologists assessed the subjective assessment and found the stone under the absence of information. We used this data to calculate the diagnostic accuracy. Results: Objective image noise was decreased after applying a deep learning tool in all images of FBP, iDose, and IMR. There was no statistical difference between iDose and deep learning-applied FBP images (10.1 ± 11.9, 9.5 ± 18.5 HU, p = 0.583, respectively). At a 100 kV-30 mAs setting, deep learning-applied FBP obtained a similar objective noise in approximately one third of the radiation doses compared to FBP. In radiation doses with settings lower than 100 kV-30 mAs, the subject image assessment (image quality, confidence level, and noise) showed deteriorated scores. Diagnostic accuracy was increased when the deep learning setting was lower than 100 kV-30 mAs, except for at 80 kV-15 mAs. Conclusions: At the setting of 100 kV-30 mAs or higher, deep learning-applied FBP did not differ in image quality compared to IR. At the setting of 100 kV-30 mAs, the radiation dose can decrease by about one third while maintaining objective noise.

247 the Effect of CT Acquisition Parameters on Extracted Radiomic Features Using Computational Phantoms

247 the Effect of CT Acquisition Parameters on Extracted Radiomic Features Using Computational Phantoms

Вычислительный фантом для дозиметрии красного костного мозга годовалого ребенка от инкорпорированных бета-излучателей

For residents of territories along the Techa River that was contaminated with radioactive substances in the 1950s, bone-seeking beta-emitting 89,90Sr were the main source of internal exposure of active (red ) bone marrow (AM). The dose of these radionuclides conditions the severity of leukemia risk for them. Improvement of the methods of internal AM dosimetry is an important task. Computational 3D phantoms of the skeleton sites are a component of the solution for this task. Simulation of radiation transfer in a heterogeneous bone model allows estimating the dose conversion factors from radionuclide activity to AM dose. This manuscript continues the series of papers covering the development of a set of computational phantoms of a reference human being of different age. The objective of the study was to develop a computational phantom of a one-year-old child skeleton for internal AM dosimetry (exposure due to incorporated beta emitters). Using the original SPSD (stochastic parametric skeletal dosimetry) model, we develop voxel 3D models of skeletal sites. Skeleton sites with active hematopoiesis were modeled as a set of phantoms of simple geometries. Distribution of AM throughout the skeleton and parameters of the phantoms were assessed on the basis of the published results of measurement done in real bones of children aged 9 months to 2 years. The generated computational phantom of a one-year-old child consisted of 39 segments. It simulates the structure of the bone tissue, location of AM, and population variability of the skeleton microstructure and size parameters.

Virtual cone-beam computed tomography simulator with human phantom library and its application to the elemental material decomposition

PurposeThe purpose of this study is to develop a virtual CBCT simulator with a head and neck (HN) human phantom library and to demonstrate the feasibility of elemental material decomposition (EMD) for quantitative CBCT imaging using this virtual simulator. MethodsThe library of 36 HN human phantoms were developed by extending the ICRP 110 adult phantoms based on human age, height, and weight statistics. To create the CBCT database for the library, a virtual CBCT simulator that simulated the direct and scattered X-ray on a flat panel detector using ray-tracing and deep-learning (DL) models was used. Gaussian distributed noise was also included on the flat panel detector, which was evaluated using a real CBCT system. The usefulness of the virtual CBCT system was demonstrated through the application of the developed DL-based EMD model for case involving virtual phantom and real patient. ResultsThe virtual simulator could generate various virtual CBCT images based on the human phantom library, and the prediction of the EMD could be successfully performed by preparing the CBCT database from the proposed virtual system, even for a real patient. The CBCT image degradation owing to the scattered X-ray and the statistical noise affected the prediction accuracy, although these effects were minimal. Furthermore, the elemental distribution using the real CBCT image was also predictable. ConclusionsThis study demonstrated the potential of using computer vision for medical data preparation and analysis, which could have important implications for improving patient outcomes, especially in adaptive radiation therapy.

Simulation of Magnetotargeting of Medicines Based on the Calculation of Permeability of Human Tissues by the Electromagnetic Field

Analysis of studies in the field of targeted delivery of drugs, genes and stem cells showed a low level of accuracy of both applied and practical research in this area. Sufficiently encouraging results were obtained with extracorporeal electromagnetic action on a pharmacological complex with a ferromagnetic nanoparticle. With this approach, it is rather difficult to implement the algorithm for introducing the drug into the topographic region (target organ), since in practice, approaches to the clinical application of drug transport technology, taking into account the physicochemical properties of human body tissues, have not been studied in detail. The available models represent various physical and mathematical approaches that do not take into account the bioelectrical and electrostatic properties of the tissues of the organisms of experimental animals and humans. The creation of algorithms and software simulation of this technology will allow calculating variable frequency variables for magnetotargeting in a human digital phantom, which will reduce time spent at the stage of pilot and clinical trials and in the future will form the applied part of the innovative technology. The article presents the methodology and results of multiphysics and mathematical modeling in the Sim4Life for Science, V7.0 package on the example of calculating the control parameters of the electromagnetic field of the region in the area of normal administration of drugs – the vessels of the forearm.

Sensor-based microwave brain imaging system (SMBIS): An experimental six-layered tissue based human head phantom model for brain tumor diagnosis using electromagnetic signals

The paper presents the preparation and measurement of six-layered human head phantoms for the sensor-based microwave brain imaging system (SMBIS) for the diagnosis of tumors in the head. The head phantom has been constructed based upon three-dimensional arrangements filled-up with numerous biochemical combinations that imitate the six brain tissues: DURA, CSF, White Matter, Gray Matter, Fat, and Skin regarding permittivity within the wideband frequency band (1 GHz to 4 GHz). For imaging purposes, the malignant and benign tumor(s) are also fabricated and placed in different locations in the 3D skull model to validate the performance of the phantom. After being formulated, the dielectric properties are measured by utilizing a dielectric kit linked with a vector network analyzer. The measured dielectric properties are compared to real human head tissue’s dielectric properties. After that, the human phantom model, including tumors, is validated using a SMBIS. The investigational dielectric characteristics of the brain tissues showed good agreement with the dielectric properties of the real brain tissues of the head. The experimental imaging outcomes demonstrated the legitimacy of the proposed six-layered tissue mimicking phantoms that can be used as an alternate to the actual human brain tissue for the diagnosis of brain tumors in SMBIS.

Impact of Noise Level on the Accuracy of Automated Measurement of CT Number Linearity on ACR CT and Computational Phantoms.

Methods for segmentation, i.e., Full-segmentation (FS) and Segmentation-rotation (SR), are proposed for maintaining Computed Tomography (CT) number linearity. However, their effectiveness has not yet been tested against noise. This study aimed to evaluate the influence of noise on the accuracy of CT number linearity of the FS and SR methods on American College of Radiology (ACR) CT and computational phantoms. This experimental study utilized two phantoms, ACR CT and computational phantoms. An ACR CT phantom was scanned by a 128-slice CT scanner with various tube currents from 80 to 200 mA to acquire various noises, with other constant parameters. The computational phantom was added by different Gaussian noises between 20 and 120 Hounsfield Units (HU). The CT number linearity was measured by the FS and SR methods, and the accuracy of CT number linearity was computed on two phantoms. The two methods successfully segmented both phantoms at low noise, i.e., less than 60 HU. However, segmentation and measurement of CT number linearity are not accurate on a computational phantom using the FS method for more than 60-HU noise. The SR method is still accurate up to 120 HU of noise. The SR method outperformed the FS method to measure the CT number linearity due to its endurance in extreme noise.

Numerical Assessment of Human EMF Exposure to Collocated and Distributed Massive MIMO Deployments in an Industrial Indoor Environment

This article presents a comparative numerical study of collocated and distributed massive multiple-input–multiple-output (MIMO) deployments at 3.5 GHz in an industrial indoor environment from the point of view of downlink human electromagnetic field (EMF) exposure. A collection of environmental models incorporating elements with stochastic geometry is generated, in which the EMF propagation is calculated using the ray-tracing (RT) method. To evaluate the human exposure, the finite-difference time-domain (FDTD) method is used, including a realistic human phantom and a user equipment model, into which the excitation is introduced based on the RT results. Single-user maximum ratio transmission and multiuser zero-forcing scenarios are studied. Small-scale EMF distributions in proximity to the phantom's head are assessed in FDTD and analysed for different user locations in the environment and user equipment placement with respect to the head. The massive MIMO hot-spot is characterized in terms of its size, instantaneous and time-averaged EMF enhancement, and position with respect to the head and the user equipment. The human exposure is assessed using the peak-spatial specific absorption rate averaged over 10 g, referenced to the hot-spot EMF amplitude, and compared to international guidelines. It is shown that the distributed deployment results in a more accurate and consistent EMF hot-spot around the user equipment with a higher average E-field gain, compared to the collocated deployment. In addition, the distributed configuration produced more compact hot-spots relative to the collocated one, leading to a more than tenfold average exposure reduction in a multiuser scenario.