Human Phantom Research Articles

A very low-profile CPW based conformal antenna for wearable/implantable applications.

In wireless communication standard 4G and 5G, the body centric network plays an important role for the wireless communication between various devices. This research relates to a wide-band conformal co-planar waveguide (CPW) antenna for wearable applications. The proposed CPW antenna is printed on 0.1 mm thick bio-compatible polymide substrate whose dielectric constant and permittivity are 3.5 and 0.02 respectively. The total area of the antenna is around 17.5 × 15 mm2 which is significantly smaller than the wearable antennas proposed in literature. The proposed antenna is designed to operate in new ISM band 5.8 GHz with the bandwidth of 5.3-6.3 GHz with 2:1 Voltage Standing Wave Ratio (VSWR). The antenna is printed on the flexible substrate and hence robustness of device is evaluated by bending analysis. It reveals the superior performance of the designed CPW antenna over the desired spectrum of operation. Specific Absorption Rate (SAR) is calculated after placing the antenna at various places of human phantom model and showed that SAR values are below 1.6 W/Kg which is the maximum margin recommended by Federal Communication Commission (FCC), i.e when tested with 1 g and 10 g of human tissue of phantom model, for the test frequency range of 5.5-6.1GHz, SAR value falls between 0.9987 and 0.921 W/Kg respectively. The antenna also shows the radiation efficiency around 92% with overall realized gain 5.2 dBi which are substantial values for wearable applications. The outcomes of this research revealed the feasibility of the recommended antenna becoming a major contender of future Internet of Things (IoT) applications.

Learning multi-site harmonization of magnetic resonance images without traveling human phantoms

Harmonization improves Magn. Reson. Imaging (MRI) data consistency and is central to effective integration of diverse imaging data acquired across multiple sites. Recent deep learning techniques for harmonization are predominantly supervised in nature and hence require imaging data of the same human subjects to be acquired at multiple sites. Data collection as such requires the human subjects to travel across sites and is hence challenging, costly, and impractical, more so when sufficient sample size is needed for reliable network training. Here we show how harmonization can be achieved with a deep neural network that does not rely on traveling human phantom data. Our method disentangles site-specific appearance information and site-invariant anatomical information from images acquired at multiple sites and then employs the disentangled information to generate the image of each subject for any target site. We demonstrate with more than 6,000 multi-site T1- and T2-weighted images that our method is remarkably effective in generating images with realistic site-specific appearances without altering anatomical details. Our method allows retrospective harmonization of data in a wide range of existing modern large-scale imaging studies, conducted via different scanners and protocols, without additional data collection.

Collaborative Preoperative Planning for Operation-Navigation Dual-Robot Orthopedic Surgery System

Intraoperative optical navigation is widely utilized in robotic surgery systems. Typically, the observation pose of the optical tracking system (OTS) is manually adjusted and then fixed throughout the surgery. However, fixed OTS suffers from limited measurement volume (MV) and visual interferences, making consistent navigation challenging in clinics. In this paper, an operation-navigation dual-robot collaborative system is proposed for orthopedic surgeries. An extra navigation robot is introduced to actively adjust the observation pose of the OTS. A collaborative preoperative planning method is proposed for this dual-robot system, including osteotomy path planning of the operation robot and collaborative planning of the navigation robot. Firstly, osteotomy paths of the operation robot are generated according to the surgery regulations and the geometric features of the vertebral foramen. Secondly, based on the generated osteotomy paths, the collaborative planning of the navigation robot is formulated into a multi-objective optimization problem to find the optimal poses of the OTS for each osteotomy plane. Compared with fixed OTS, active navigation is capable of keeping all the targets within the MV of the OTS throughout the surgery. Semi-laminectomy on a human spine phantom is adopted as an example to experimentally evaluate the effectiveness of the proposed method. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —As the demand for robot-assisted surgery is increasing, the precision of operation has become one of the key safety requirements. Preoperative planning provides guidance for the surgeon, and intraoperative navigation monitor the status of the lesion and the surgical tool in real-time. In conventional intraoperative optical navigation, the OTS is manually adjusted and remains stationary. However, the limited MV and the visual interferences introduce risks and uncertainties to the surgical system. In order to address the limitations of fixed OTS, an operation-navigation dual-robot collaborative system is proposed for orthopedic surgeries, which is composed of a surgical operation module and an active navigation module. The navigation robot is used to actively adjust the pose of the OTS. A collaborative preoperative planning for the operation-navigation dual-robot orthopedic surgery system is proposed in this paper. The effectiveness of the proposed method is verified on a human spine phantom. Experimental results show that the active navigation provides more freedom to the overall system by freely adjusting the OTS, which ensures the stability of the surgical navigation. In future work, efforts will be directed toward the identification and avoidance of the obstacle.

Investigation of Imaging Conditions Using Human Body Equivalent Phantom and Neonatal Phantom in Portable Chest Radiography of Newborns

Investigation of imaging conditions using human body equivalent phantom and neonatal phantom in portable chest radiography of newborns. Although attempts have been made to reduce dose by image processing in portable X-ray radiography of neonates, no evaluation has been made at the raw data level of the images. In this study, we investigated dose reduction from the current imaging conditions using a simulated phantom and a neonatal phantom in terms of raw data level image quality and incident surface dose. The pixel values of each region were calculated from chest photographs of newborn infants taken at 60 kV and 2.0 mAs, and the thickness and combination of acrylic, aluminum, and copper were adjusted to create a simulated phantom with equivalent pixel values. The SdNR and incident surface dose at each site obtained from the simulated phantom were compared to obtain imaging conditions equivalent to or better than 60 kV, 2.0 mAs. The neonatal phantom was imaged, and the CNR of the processed images was compared to that of 60 kV, 2.0 mAs. SdNR and incident surface dose results showed that 62 kV, 1.8 mAs was superior. Comparison with neonatal phantoms showed no significant difference. The simulated phantom was used to reproduce the clinical situation and to obtain excellent imaging conditions.

Effect of Gonadal Protection on Image Quality in Frontal Hip Radiography

In recent years, there has been a growing movement in Western countries toward the abolition of gonadal protection during radiography. The reasons for this recommendation are that there are few reports of increased risk of genetic effects, that the ovarian dose is not due to direct X-rays but due to internally scattered X-rays that cannot be shielded, and that the presence of gonadal protection may adversely affect the automatic exposure control mechanism and may mask important findings. In addition, the gonadal protection is a large high absorber of X-rays, and its presence in the irradiation field may have some effect on image quality, but the effect of the gonadal protection on image quality has not been clarified. In addition, after the abolition of gonadal protection, the optimal irradiation field setting is expected to become even more important to avoid unnecessary exposure. In this study, we investigated the effect of gonadal protection on image quality in frontal hip radiographs of adults with different radiation qualities and clarified the image quality under conditions in which the irradiation field is appropriately narrowed. Frontal hip radiographs were taken using a human phantom as the subject, and the image quality of the femoral head was evaluated. Two irradiation fields were used: (a) 14×17 inch field and (b) an appropriate field (11.6×15 inch) that does not impair the reference line and image information necessary for reading hip joint images. The imaging tube voltage was set at 70 kV, and conditions for adding a copper filter were also considered. The incident surface air kerma was set to 1.25 mGy. The incident surface dose at this time was sufficiently lower than the diagnostic reference level (2.5 mGy) in Japan and was judged to be appropriate for imaging using an indirect conversion flat panel detector. The image quality evaluation item was the signal difference to noise ratio (SdNR) including scatterers. The SdNR decreased by 4.6% when a gonadal shield was placed, indicating that the gonadal shield reduced image quality. When the irradiation field size was appropriately narrowed down, SdNR slightly increased or decreased depending on the quality of the imaging material, but the change was small compared to the change in SdNR with and without the gonadal protection shield. The results of this study confirm that the elimination of gonadal protection in hip radiography has significant advantages, such as reducing unnecessary X-ray exposure while ensuring image quality, when the irradiation field is set appropriately.

ADVANCED ULTRAWIDEBAND PATCH ANTENNA FOR WEARABLE AND WBAN APPLICATIONS

Present communication devices are adopting an application-centric approach with the integration of electronic gadgets into wearable accessories in recent years. This paper presents a wearable antenna with a flexible textile substrate. The design comprises a low-profile, textile-based UWB (3.1-10.6 GHz) antenna of 25 &amp;times; 20 &amp;times; 1 mm&lt;sup&gt;3&lt;/sup&gt; size with a defected ground structure. Design antenna performance characteristics have been simulated in Computer Simulation Technology studio. It offers a gain of 4.204 dBi at 5.11 GHz frequency and 2.993 dBi at 7.39 GHz frequency using a cotton substrate with a 1.6 dielectric constant. A simulated testing of the design antenna on a human body phantom has resulted in a gain of 0.697 dBi with a return loss of -30.863dB and 1.058 VSWR at 5.3125 GHz frequency. A specific absorption rate value of 1.64 W/kg of the designed antenna for 10 g tissue shows that it is safe for the human body. The patch antenna of the paper is promising for wearable, medical imaging, tumor detection, and other wireless body area network (WBAN) biomedical applications.

Reduction of cervical vertebra ghost images in panoramic radiography using vertical dual exposure.

To evaluate the image quality of vertical dual-exposure panoramic radiography (PR), which merges two PR images taken at different focus heights to reduce ghost images of cervical vertebrae (CV) and intervertebral spaces (IVS) in the incisor region. PR images of an aluminum block, a CV phantom and a human head phantom were taken at 0 mm and merged with and subtracted from PR images taken at other heights (0, 5, 10, 15, and 20 mm) to create new images, e.g., Merg0 + 15 mm and Sub0 - 10 mm. The subtracted images were analyzed subjectively according to the uniformity on the line profile. Merged images were evaluated subjectively by six raters to determine the influence of the ghost images. Objective evaluation revealed a positional shift in the ghost images according to the height of the focus for both phantoms. In the subjective evaluation, the normal PR (Merg0 + 0 mm) showed the worst score, indicating strong influence of CV and IVS ghost images. The vertical dual-exposure PR method, which merges PR images taken at the normal position and a higher X-ray focus, can reduce CV and IVS ghost images in the incisor region.

An Ultrasonic Transceiver for Non-Invasive Intracranial Pressure Sensing.

This paper presents a 9-mW ultrasonic through-transmission transceiver (TRX) for portable, non-invasive intracranial pressure (ICP) sensing. It employs two ultrasound transducers placed at the temporal bone windows to measure changes in the ultrasonic time-of-flight (ToF), based on which the skull expansion and the corresponding ICP waveform are derived. Key components include a high-efficiency Class-DE power amplifier (PA) with 95% efficiency and an output swing of 15.8 VPP, along with a successive approximation register (SAR) delay-locked loop (DLL)-based time-to-digital converter (TDC) with 29.8 ps resolution and 122 ns range. Other than electrical characterization, the sensor is validated through two demonstrations using a water tank setup and a human head phantom setup, respectively. It demonstrates a high correlation of R2 = 0.93 with a medical-grade invasive ICP sensor. The proposed system offers high accuracy, low power consumption, and reliable performance, making it a promising solution for real-time, portable, non-invasive ICP monitoring in various clinical settings.

Dynamic sub-array selection-based energy-efficient localization and tracking method to power implanted medical devices in scattering heterogenous media employing ultrasound.

Ultrasound (US) as a wireless power transfer methodology has drawn considerable attention from the implantable medical devices (IMD) research community. Beamforming (BF) using an external transducer array patch (ETAP) has been proposed as a robust localization scheme to find a mm-sized IMD inside the human body. However, for applications focusing on deep and shallow IMDs, optimum resource utilization at the ETAP is a major power efficiency concern for energy-constrained wearable patches. Moreover, misalignment tolerance due to IMD movements (respiratory and patient ambulatory reasons) relative to the ETAP remains a challenge. This paper presents an energy-efficient method to localize a mm-sized IMD through the dynamic selection of a sub-array within the ETAP. It is fully adaptive to the heterogeneity of the media and requires no a priori knowledge of the IMD. To improve the tolerance to IMD movements, tracking is implemented by adding and subtracting elements on the sub-array such that the sub-array electrically follows the IMD movement. Furthermore, it is shown that a minimum sampling frequency of 10X the US frequency can improve the tolerance to random noise. K-wave simulations in MATLAB are performed in different heterogenous, scattering biological media to prove the efficacy of the proposed method over standard BF methods. Measurement results in heterogenous scattering media consisting of a 3D-printed human ribs phantom and a partially blocking multipath cancellous bone phantom show an energy efficiency improvement of 10.53X and 14.4X compared to the delay-and-sum beamforming method and the unfocused transmission employing all the elements of the ETAP, respectively.

Determination of Exposure during Handling of &lt;sup&gt;125&lt;/sup&gt;I Seed Using Thermoluminescent Dosimeter and Monte Carlo Method Based on Computational Phantom

Background: The thermoluminescent dosimeter (TLD) and Monte Carlo (MC) dosimetry are carried out to determine the occupational dose for personnel in the handling of &lt;sup&gt;125&lt;/sup&gt;I seed sources.Materials and Methods: TLDs were placed in different layers of the Alderson-Rando phantom in the thyroid, lung and also eyes and skin surface. An &lt;sup&gt;125&lt;/sup&gt;I seed source was prepared and its activity was measured using a dose calibrator and was placed at two distances of 20 and 50 cm from the Alderson-Rando phantom. In addition, the Monte Carlo N-Particle Extended (MCNPX 2.6.0) code and a computational phantom with a lattice-based geometry were used for organ dose calculations.Results and Discussion: The comparison of TLD and MC results in the thyroid and lung is consistent. Although the relative difference of MC dosimetry to TLD for the eyes was between 4% and 13% and for the skin between 19% and 23%, because of the existence of a higher uncertainty regarding TLD positioning in the eye and skin, these inaccuracies can also be acceptable. The isodose distribution was calculated in the cross-section of the head phantom when the &lt;sup&gt;125&lt;/sup&gt;I seed was at two distances of 20 and 50 cm and it showed that the greatest dose reduction was observed for the eyes, skin, thyroid, and lungs, respectively. The results of MC dosimetry indicated that for near the head positions (distance of 20 cm) the absorbed dose rates for the eye lens, eye and skin were 78.1±2.3, 59.0±1.8, and 10.7±0.7 µGy/mCi/hr, respectively. Furthermore, we found that a 30 cm displacement for the &lt;sup&gt;125&lt;/sup&gt;I seed reduced the eye and skin doses by at least 3- and 2-fold, respectively.Conclusion: Using a computational phantom to monitor the dose to the sensitive organs (eye and skin) for personnel involved in the handling of &lt;sup&gt;125&lt;/sup&gt;I seed sources can be an accurate and inexpensive method.

MIDOS: a novel stochastic model towards a treatment planning system for microsphere dosimetry in liver tumors.

Transarterial radioembolization (TARE) procedures treat liver tumors by injecting radioactive microspheres into the hepatic artery. Currently, there is a critical need to optimize TARE towards a personalized dosimetry approach. To this aim, we present a novel microsphere dosimetry (MIDOS) stochastic model to estimate the activity delivered to the tumor(s), normal liver, and lung. MIDOS incorporates adult male/female liver computational phantoms with the hepatic arterial, hepatic portal venous, and hepatic venous vascular trees. Tumors can be placed in both models at user discretion. The perfusion of microspheres follows cluster patterns, and a Markov chain approach was applied to microsphere navigation, with the terminal location of microspheres determined to be in either normal hepatic parenchyma, hepatic tumor, or lung. A tumor uptake model was implemented to determine if microspheres get lodged in the tumor, and a probability was included in determining the shunt of microspheres to the lung. A sensitivity analysis of the model parameters was performed, and radiation segmentectomy/lobectomy procedures were simulated over a wide range of activity perfused. Then, the impact of using different microspheres, i.e., SIR-Sphere®, TheraSphere®, and QuiremSphere®, on the tumor-to-normal ratio (TNR), lung shunt fraction (LSF), and mean absorbed dose was analyzed. Highly vascularized tumors translated into increased TNR. Treatment results (TNR and LSF) were significantly more variable for microspheres with high particle load. In our scenarios with 1.5 GBq perfusion, TNR was maximum for TheraSphere® at calibration time in segmentectomy/lobar technique, for SIR-Sphere® at 1-3 days post-calibration, and regarding QuiremSphere® at 3 days post-calibration. This novel approach is a decisive step towards developing a personalized dosimetry framework for TARE. MIDOS assists in making clinical decisions in TARE treatment planning by assessing various delivery parameters and simulating different tumor uptakes. MIDOS offers evaluation of treatment outcomes, such as TNR and LSF, and quantitative scenario-specific decisions.

Out-of-field dosimetry using a validated PHITS model and computational phantom in clinical BNCT.

The out-of-field radiation dose for boron neutron capture therapy (BNCT), which results from both neutrons and γ-rays, has not been extensively evaluated. To safely perform BNCT, the neutron and γ-ray distributions inside the treatment room and the whole-body dose should be evaluated during commissioning. Although, certain previous studies have evaluated the whole-body dose in the clinical research phase, no institution providing BNCT covered by health insurance has yet validated the neutron distribution inside the room and the whole-body dose. To validate the Monte Carlo model of the BNCT irradiation room extended for the whole-body region and evaluate organ-at-risk (OAR) doses using the validated model with a human-body phantom. First, thermal neutron distribution inside the entire treatment room was measured by placing Au samples on the walls of the treatment room. Second, neutron and gamma-ray dose-rate distributions inside a human-body water phantom were measured. Both lying and sitting positions were considered. Bare Au, Au covered by Cd (Au+Cd), In, Al, and thermoluminescent dosimeters were arranged at 11 points corresponding to locations of the OARs inside the phantom. After the irradiation, γ-ray peaks emitted from the samples were measured by a high-purity germanium detector. The measured counts were converted to the reaction rate per unit charge of the sample. These measurements were compared with results of simulations performed with the Particle and Heavy Ion Transport code System (PHITS). A male adult mesh-type reference computational phantom was used to evaluate OAR doses in the whole-body region. The relative biological effectiveness (RBE)-weighted doses and dose-volume histograms (DVHs) for each OAR were evaluated. The median dose (D50% ) and near-maximum dose (D2% ) were evaluated for 14 OARs in a 1-h-irradiation process. The evaluated RBE-weighted doses were converted to equivalent doses in 2Gy fractions. Experimental results within 60cm from the irradiation center agreed with simulation results within the error bars except at±20, 30cm, and those over 70cm corresponded within one digit. The experimental results of reaction rates or γ-ray dose rate for lying and sitting positions agreed well with the simulation results within the error bars at 8, 4, 11, 7 and 7, 4, 7, 6, 5, 6 out of 11 points, respectively, for Au, Au+Cd, In, Al, and TLD. Among the detectors, the discrepancies in reaction rates between experiment and simulation were most common for Au+Cd, but were observed randomly for measurement points (brain, lung, etc.). The experimental results of γ-ray dose rates were systematically lower than simulation results at abdomen and waist regions for both positions. Extending the PHITS model to the whole-body region resulted in higher doses for all OARs, especially 0.13Gy-eq increase for D50% of the left salivary gland. The PHITS model for clinical BNCT for the whole-body region was validated, and the OAR doses were then evaluated. Clinicians and medical physicists should know that the out-of-field radiation increases the OAR dose in the whole-body region.

Surface-based anthropomorphic bone structures for use in high-resolution simulated medical imaging

Objective. Virtual imaging trials enable efficient assessment and optimization of medical image devices and techniques via simulation rather than physical studies. These studies require realistic, detailed ground-truth models or phantoms of the relevant anatomy or physiology. Anatomical structures within computational phantoms are typically based on medical imaging data; however, for small and intricate structures (e.g. trabecular bone), it is not reasonable to use existing clinical data as the spatial resolution of the scans is insufficient. In this study, we develop a mathematical method to generate arbitrary-resolution bone structures within virtual patient models (XCAT phantoms) to model the appearance of CT-imaged trabecular bone. Approach. Given surface definitions of a bone, an algorithm was implemented to generate stochastic bicontinuous microstructures to form a network to define the trabecular bone structure with geometric and topological properties indicative of the bone. For an example adult male XCAT phantom (50th percentile in height and weight), the method was used to generate the trabecular structure of 46 chest bones. The produced models were validated in comparison with published properties of bones. The utility of the method was demonstrated with pilot CT and photon-counting CT simulations performed using the accurate DukeSim CT simulator on the XCAT phantom containing the detailed bone models. Main results. The method successfully generated the inner trabecular structure for the different bones of the chest, having quantiative measures similar to published values. The pilot simulations showed the ability of photon-counting CT to better resolve the trabecular detail emphasizing the necessity for high-resolution bone models. Significance. As demonstrated, the developed tools have great potential to provide ground truth simulations to access the ability of existing and emerging CT imaging technology to provide quantitative information about bone structures.

Development and validation of the low-cost pregnant female physical phantom for fetal dosimetry in MV photon radiotherapy.

Monte Carlo (MC) simulations or measurements in anthropomorphic phantoms are recommended for estimating fetal dose in pregnant patients in radiotherapy. Among the many existing phantoms, there is no commercially available physical phantom representing the entire pregnant woman. In this study, the development of a low-cost, physical pregnant female phantom was demonstrated using commercially available materials. This phantom is based on the previously published computational phantom. Three tissue substitution materials (soft tissue, lung and bone tissue substitution) were developed. To verify Tena's substitution tissue materials, their radiation properties were assessed and compared to ICRP and ICRU materials using MC simulations in MV radiotherapy beams. Validation of the physical phantom was performed by comparing fetal doses obtained by measurements in the phantom with fetal doses obtained by MC simulations in computational phantom, during an MV photon breast radiotherapy treatment. Materials used for building Tena phantom are matched to ICRU materials using physical density, radiation absorption properties and effective atomic number. MC simulations showed that percentage depth doses of Tena and ICRU material comply within 5% for soft and lung tissue, up to 25cm depth. In the bone tissue, the discrepancy is higher, but again within 5% up to the depth of 5cm. When the phantom was used for fetal dose measurements in MV photon breast radiotherapy, measured fetal doses complied with fetal doses calculated using MC simulation within 15%. Physical anthropomorphic phantom of pregnant patient can be manufactured using commercial materials and with low expenses. The files needed for 3D printing are now freely available. This enables further studies and comparison of numerical and physical experiments in diagnostic radiology or radiotherapy.

Anthropomorphic breast phantoms for radiology imaging: a review

Phantoms are used to validate diagnostic imaging methods or improve the skills of medical professionals. For instance, they allow conducting an unlimited number of imaging studies during medical training, assessing image quality, optimizing radiation dose, and testing novel techniques and equipment. Researchers in breast imaging use anthropomorphic models to validate, assess, and optimize new methods for diagnosing breast diseases. Such models also facilitate control over the quality of diagnostic systems, help optimize clinical protocols, and improve image reconstruction algorithms. Realistic simulation of the breast tissue is essential to address the challenges of advancing X-ray mammary gland studies. The review aimed to describe phantoms currently available for diagnostic imaging and the way they were fabricated. In this literature review, PubMed, eLIBRARY, and Google Scholar databases were screened for relevant articles. Thus, 72 articles and 13 conference papers were included. The study two major types of breast phantoms: computational and physical. Specifically, computational phantoms are classified into subgroups depending on the data they use. These include mathematical models, tissue samples, and medical images of the breast. The classification of the physical phantoms is based on their manufacturing process: casting silicone-like substances, 3D printing with resins and plastics, or printing on paper using X-ray contrast ink. Computational phantoms are generally advantageous with respect to versatility, efficiency, precision, and safety and allow the generation of large amounts of virtual data. Physical phantoms provide the most realistic diagnostic images without the need for a patient and allow performing an unlimited number of radiological studies.

A Review of Organ Dose Calculation Methods and Tools for Patients Undergoing Diagnostic Nuclear Medicine Procedures

Exponential growth has been observed in nuclear medicine procedures worldwide in the past decades. The considerable increase is attributed to the advance of positron emission tomography and single photon emission computed tomography, as well as the introduction of new radiopharmaceuticals. Although nuclear medicine procedures provide undisputable diagnostic and therapeutic benefits to patients, the substantial increase in radiation exposure to nuclear medicine patients raises concerns about potential adverse health effects and calls for the urgent need to monitor exposure levels. In the current article, model-based internal dosimetry methods were reviewed, focusing on Medical Internal Radiation Dose (MIRD) formalism, biokinetic data, human anatomy models (stylized, voxel, and hybrid computational human phantoms), and energy spectrum data of radionuclides. Key results from many articles on nuclear medicine dosimetry and comparisons of dosimetry quantities based on different types of human anatomy models were summarized. Key characteristics of seven model-based dose calculation tools were tabulated and discussed, including dose quantities, computational human phantoms used for dose calculations, decay data for radionuclides, biokinetic data, and user interface. Lastly, future research needs in nuclear medicine dosimetry were discussed. Model-based internal dosimetry methods were reviewed focusing on MIRD formalism, biokinetic data, human anatomy models, and energy spectrum data of radionuclides. Future research should focus on updating biokinetic data, revising energy transfer quantities for alimentary and gastrointestinal tracts, accounting for body size in nuclear medicine dosimetry, and recalculating dose coefficients based on the latest biokinetic and energy transfer data.

Design consideration and recent developments in flexible, transparent and wearable antenna technology: A review

AbstractThe wearable technology and flexible electronics have been convoluted in modern technologies and many of applications especially insensors, biomedical, displays, solar panels, glasses, smart cities, integrated circuits, and wireless body area network (WBAN). They offer capability of mechanical deformation conditions mainly stretchable, bendable, foldable features and capable to severe environmental conditions. Nowadays, a device having lightweight, low‐profile, compact in size and flexible deployment on the system platforms is preferred. With the flexibility in the design of the antenna, they require flexible, robust, easy to wear, visually imperceptible, unobtrusiveness, and planar material for the realization. The characteristics of the wearable antenna may vary according to the material conductivity and their optical transparency, substrate selection and their thickness along with permittivity opted for and mechanical deformation behavior. Generally, the textile material is utilized to design the flexible wearable antenna due to material flexibility which can minimize the losses and enhance the antenna performance. Conversely, the visually imperceptible and flexible material is utilized to design transparent wearable antenna due to appropriate trade‐off between conductivity and optical transparency of the materials. For diverse WBAN applications, the flexible, transparent, and wearable antennas are utilized. This paper elaborates the comprehensive review and the state‐of‐the‐art research on the diverse categories of the wearable antennas based on the substrate characteristics such as flexibility and transparency. In addition, it provides the broad investigation of the flexible and transparent materials utilized to design wearable antennas and different tissue layers with their dielectric properties to develop the human multilayer phantom model.

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

The red bone marrow (RBM) exposure due to bone-seeking radionuclides can lead to grave medical consequences. In particular, the increased risk of leukemia in people exposed due to contamination of the Techa River in 1950s is associated with the RBM exposure due to 89,90Sr. Improvement of the internal RBM dosimetry methods includes the development of computational phantoms that represent 3D models of the skeletal sites. Modeling radiation transport within such phantoms enables estimation of conversion factors from the radionuclide activity in the bone to the RBM dose rate. This paper is an extension study focused on generating a set of computational phantoms representing skeletons of individuals of different ages. The aim was to develop a computational phantom representing a 5-yearold child for internal RBM dosimetry from incorporated beta emitters. The phantoms of the skeletal sites with active hematopoiesis were created using the original Stochastic Parametric Skeletal Dosimetry (SPSD) method. With this method, every such site represented a set of smaller phantoms of simple geometric shape. RBM distribution across the skeleton, bone size, characteristics of bone micro-architecture, as well as density and chemical composition of the simulated media (RBM, bone) were determined based on the published data. As a result, a computational phantom of the major skeletal sites with active hematopoiesis representing a 5-year-old child was generated that included 43 phantoms of bone fragments. Linear dimensions of phantoms were within 3–75 mm. Micro-architecture parameters varied greatly: BV/TV ratio —13–52%, Tb. Th. — 0.09–0.29 mm, Tb. Sp. —0.48–0.98 mm.

Compact size antenna for skin implantable medical devices

Abstract This research work presents an implantable antenna that operates at 5.8 GHz. By using a radiator with a loop-based design, the antenna can be made smaller. Radiator is made up of three connected rectangular loops. On the substrate’s back side, an I-shaped ground plane is used. As substrate and superstrate, polydimethylsiloxane (PDMS) with dimensions of 7 mm × 5 mm × 0.3 mm is used. The conducting sections are made using copper foil that is 30 µm thick. The suggested antenna is examined by the implantable medical device using realistic human scalp phantom models and a homogenous skin box. Simulated study revealed that it operates around 5.8 GHz with a bandwidth from 5.69 to 5.92 GHz. The specific absorption rate was 0.28 and 0.26 W/kg for skin box and human scalp phantoms, respectively, at 1 mW input power across 1 g volume tissue.

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.