Higher Specific Absorption Rate Values Research Articles

A magnetic cross-linked alginate-biobased nanocomposite with anticancer and hyperthermia activities

This research study focuses on a new magnetic nanobiocomposite designed and synthesized by the formation of cross-linked alginate (Alg) hydrogel using CaCl2 cross-linker agent, its modification with flaxseed mucilage hydrogel and silk fibroin (SF) biopolymer extracted, and as well, the in-situ synthesis of Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) in the presence of this biopolymeric substrate. FT-IR, EDX, FE-SEM, XRD, VSM, and TG technical analyses clarified the physical and chemical features of magnetic cross-linked Alg/flaxseed mucilage hydrogel/SF nanobiocomposite. Following the structural characterization of this magnetic natural-based composition, the in-vitro cytotoxicity and hemolysis assay studies with different concentrations resulted in prominent biological outcomes. The survival rates of normal HEK293T cells (95.74%, 94.18%) and breast cancer BT549 cells (79.23%, 77.76%) after 48 and 72 h verified the biocompatibility and anticancer properties of this new nanobiocomposite. Also, less than 5% of the hemolytic effect disclosed its hemocompatibility. Furthermore, a high specific absorption rate value (72.42 W/g) is generated by 1 mg/mL of this magnetic nanobiocomposite. Overall, it can be deduced that magnetic responsive cross-linked Alg/flaxseed mucilage hydrogel/SF nanobiocomposite could functionally perform in magnetic hyperthermia treatment.

Evaluation of neonatal outcomes according to the specific absorption rate values of phones used during pregnancy.

The aim was to compare neonatal outcomes according to cell phone specific absorption rate (SAR) levels and daily time spent on cell phones by pregnant women. Women who gave birth at Konya City Hospital between September 2020 and February 2021 were included in this retrospective study. Gestational ages, birth weight, birth length, head circumference, sex, 5-minute APGAR scores, neonate postpartum resuscitation requirement, delivery type, the model of phone used by the pregnant women, and the average time spent on the phone during a day were recorded. To determine the relation between the SAR values of the phones used and delivering a small for gestational age (SGA) baby, receiver operating characteristic curve analysis was performed. In total 1495 pregnant women were included. The rate of delivering a SGA fetus was significantly higher in women who used phones with higher SAR values (p=0.001). The cut-off value for the SAR level was 1.23 W/kg with 69.3% sensitivity and 73.0% specificity (area under the curve: 0.685; 95% confidence interval: 0.643-0.726). No correlation was found between time spent on the phone and SGA birth rate. Although both phone SAR values and time spent on the phone were higher in the symmetrical SGA group compared to the asymmetrical SGA group, the difference was not significant (p>0.05). Although the women who had preterm delivery had higher phone SAR values and had spent more time on the phone compared to those who had term deliveries, the difference was again not significant (p>0.05). As the SAR values of cell phones used during pregnancy increased, there was a trend towards delivering a SGA baby.

Tailored nanoparticles for magnetic hyperthermia: Highly stable aqueous dispersion of Mn-substituted magnetite superparamagnetic nanoparticles by double surfactant coating for improved heating efficiency

This study presents a significant advancement in cancer therapy through the application of Mn-substituted magnetite superparamagnetic (SPM) nanoparticles, highlighting the potential of magnetic fluid hyperthermia (MFH) as an effective modality. However, its clinical applications have been limited by challenges such as low heating performance, agglomeration of magnetic nanoparticles (MNPs) in blood veins, and cytotoxicity. To address these crucial issues, surface engineered MNPs were synthesised by adopting a reverse micelles-based co-precipitation approach that effectively overcomes MNP agglomeration, ensuring uniform dispersion of the nanoparticles. Through careful optimization of Mn ion substitution within magnetite, we have achieved a significant enhancement in the heating performance of the magnetite SPM nanoparticles. The substitution of Mn2+ ions in magnetite has notably increased the specific absorption rate (SAR) value, as evidenced by a remarkable 181% increase (SAR: 510 kW/kg) obtained using the Box Lucas Method. This enhancement can be attributed to the elevated saturation magnetization resulting from the appropriate cation distribution within the MNPs. Furthermore, the increase in spin relaxation time with higher Mn concentration also contributes to the improvement in SAR values as MNPs retain their magnetic moments for an extended period before relaxing, leading to enhanced energy dissipation and higher SAR values. The hemolysis assays demonstrated minimal hemolysis rates (<5%) when exposed to red blood cells (RBCs), confirming the high biocompatibility of the MNPs. Additionally, MTT assays revealed excellent cytocompatibility (>90% cell viability) for Human Embryonic Kidney (HEK-293) cells across all compositions, further affirming the potential of these MNPs for clinical treatments. Overall, this study unveils a sustainable approach for cancer therapy using Mn-substituted magnetite SPM nanoparticles. Their remarkable heating performance and excellent biocompatibility make them promising for clinical applications in MFH.

Design and fabrication of a magnetic nanobiocomposite based on flaxseed mucilage hydrogel and silk fibroin for biomedical and in-vitro hyperthermia applications

In this research work, a magnetic nanobiocomposite is designed and presented based on the extraction of flaxseed mucilage hydrogel, silk fibroin (SF), and Fe3O4 magnetic nanoparticles (Fe3O4 MNPs). The physiochemical features of magnetic flaxseed mucilage hydrogel/SF nanobiocomposite are evaluated by FT-IR, EDX, FE-SEM, TEM, XRD, VSM, and TG technical analyses. In addition to chemical characterization, given its natural-based composition, the in-vitro cytotoxicity and hemolysis assays are studied and the results are considerable. Following the use of highest concentration of magnetic flaxseed mucilage hydrogel/SF nanobiocomposite (1.75 mg/mL) and the cell viability percentage of two different cell lines including normal HEK293T cells (95.73%, 96.19%) and breast cancer BT549 cells (87.32%, 86.9%) in 2 and 3 days, it can be inferred that this magnetic nanobiocomposite is biocompatible with HEK293T cells and can inhibit the growth of BT549 cell lines. Besides, observing less than 5% of hemolytic effect can confirm its hemocompatibility. Furthermore, the high specific absorption rate value (107.8 W/g) at 200 kHz is generated by a determined concentration of this nanobiocomposite (1 mg/mL). According to these biological assays, this magnetic responsive cytocompatible composite can be contemplated as a high-potent substrate for further biomedical applications like magnetic hyperthermia treatment and tissue engineering.

Specific absorption rate of different phone brands and health students’ awareness, attitude, and performance towards mobile phone hazards

Background: This study aimed to assess the specific absorption rate (SAR) due to the exposure to the radiations from different brands of cellphones, and to compare it with guideline values. The SAR is calculated using the mathematic equation based on the measured energy. Methods: In this regard, 204 cellphones from different brands were randomly surveyed. A questionnaire composed of demographic and self-reported questions was designed to survey the students’ awareness and attitude about cellphone brands, usage duration and observed health effects. The Kolmogorov-Smirnov test was used for statistical analysis at frequencies of 900 and 1800 MHz and the differences between brands were assessed by the Kruskal-Wallis test. Results: According to the results, it was found that 46.7% and 8.4% of people used cellphones for less than 4 and more than 12 hours per day, respectively. According to the statistical tests, students with higher talk time, sent messages, and Internet usage, and those using wireless hands-free, had the most reported symptoms of headache, tinnitus, eye burning and eyestrain, sleep disturbances, and skin color changes. Conclusion: The authors found that there was no significant difference between different brands based on the SAR values. However, Samsung and Nokia brands had the highest SAR values and ASUS brand had the lowest ones. Also, the type of game apps (online/offline) was significantly correlated with possible health effects. Therefore, regarding these cases, as well as the fact that many dangers of cellphone use are unknown, it is recommended to use cellphones cautiously.

Numerical Modeling and Computer Simulation of a Meander Line Antenna for Alzheimer's Disease Treatment, a Feasibility Study.

Alzheimer's disease (AD) is a brain disorder that eventually causes memory loss and the ability to perform simple cognitive functions; research efforts within pharmaceuticals and other medical treatments have minimal impact on the disease. Our preliminary biological studies showed that Repeated Electromagnetic Field Stimulation (REFMS) applying an EM frequency of 64 MHz and a specific absorption rate (SAR) of 0.4 - 0.9 W/kg decrease the level of amyloid-β peptides (Aβ), which is the most likely etiology of AD. This study emphasizes uniform E/H field and SAR distribution with adequate penetration depth penetration through multiple human head layers driven with low input power for safety treatments. In this work, we performed numerical modeling and computer simulations of a portable Meander Line antenna (MLA) to achieve the required EMF parameters to treat AD. The MLA device features a low cost, small size, wide bandwidth, and the ability to integrate into a portable system. This study utilized a High-Frequency Simulation System (HFSS) in the design of the MLA with the desired characteristics suited for AD treatment in humans. The team designed a 24-turn antenna with a 60 cm length and 25 cm width and achieved the required resonant frequency of 64 MHz. Here we used two numerical human head phantoms to test the antenna, the MIDA and spherical head phantom with six and seven tissue layers, respectively. The antenna was fed from a 50-Watt input source to obtain the SAR of 0.6 W/kg requirement in the center of the simulated brain tissue layer. We found that the E/H field and SAR distribution produced was not homogeneous; there were areas of high SAR values close to the antenna transmitter, also areas of low SAR value far away from the antenna. This paper details the antenna parameters, the scattering parameters response, the efficiency response, and the E and H field distribution; we presented the computer simulation results and discussed future work for a practical model.

Albumin Stabilized Fe@C Core-Shell Nanoparticles as Candidates for Magnetic Hyperthermia Therapy.

Carbon-encapsulated iron nanoparticles (Fe@C) with a mean diameter of 15 nm have been synthesized using evaporation–condensation flow–levitation method by the direct iron-carbon gas-phase reaction at high temperatures. Further, Fe@C were stabilized with bovine serum albumin (BSA) coating, and their electromagnetic properties were evaluated to test their performance in magnetic hyperthermia therapy (MHT) through a specific absorption rate (SAR). Heat generation was observed at different Fe@C concentrations (1, 2.5, and 5 mg/mL) when applied 331 kHz and 60 kA/m of an alternating magnetic field, resulting in SAR values of 437.64, 129.36, and 50.4 W/g for each concentration, respectively. Having such high SAR values at low concentrations, obtained material is ideal for use in MHT.

CTAB assisted synthesis of MnFe2O4@ SiO2 nanoparticles for magnetic hyperthermia and MRI application

Magnetic fluid hyperthermia (MFH) has been proven as a promising cancer therapeutic approach in conjunction with chemotherapy or physiotherapy in patients. The research to find innovative materials with a higher specific absorption rate (SAR) to reduce the dose of magnetic nanoparticles in tumor treatment through MFH while being also adequate for Magnetic Resonance Imaging (MRI) is important. Herein, MnFe2O4 NPs were synthesized with different sizes, using NaOH or NH4OH as a reducing agent, via a green-assisted hydrothermal route. A tetraethyl orthosilicate with the assist of cetrimonium bromide was used to fabricate SiO2 @MnFe2O4 NPs. Based on the Mössbauer and XRD results an undesired amount of α-Fe2O3 was found in the samples synthesized with NH4OH. Concentration-dependent cellular toxicity values were evaluated by invitro 3-(4,5 dimethylthiazol-2-yl)−2,5-diphenyltetrazolium bromide (MTT) assay on A549 cells, where bare and silica coated nanoparticles exhibited non-toxicity below 691 µg/mL and 566 µg/mL, respectively. The ability of bare MnFe2O4 as the MRI contrast agent was higher compared to the silica-coated sample. The heating efficiency of the ferrofluids was recorded at 128 kHz and 10 kA/m and the highest SAR value was 39 W/g for the pristine MnFe2O4 NPs, making them promising potential materials in MRI and cancer treatment.

Towards optimal thermal distribution in magnetic hyperthermia

A linear combination of spherically symmetric heat sources is shown to provide optimal stationary thermal distribution in magnetic hyperthermia. Furthermore, such spatial location of heat sources produces suitable temperature distribution in biological medium even for assemblies of magnetic nanoparticles with a moderate value of specific absorption rate (SAR), of the order of 100–150 W/g. We also demonstrate the advantage of using assemblies of spherical magnetic nanocapsules consisting of metallic iron nanoparticles covered with non magnetic shells of sufficient thickness in magnetic hyperthermia. Based on numerical simulation we optimize the size and geometric structure of biocompatible spherical capsules in order to minimize the influence of strong magneto-dipole interaction between closely spaced nanoparticles. It is shown that assembly of capsules can provide sufficiently high SAR values of the order of 250–400 W/g at moderate amplitudes H0 = 50–100 Oe and frequencies f = 100–200 kHz of alternating magnetic field, being appropriate for application in clinics.

Measurement and Calculation of SAR Due to 900 MHz Electromagnetic Waves

Purpose: The widespread use of mobile phones and Base Transceiver Stations (BTSs) has generated public concern about exposure to Electromagnetic (EM) waves. In this study, the electric field intensity and Specific Absorption Rate (SAR) in the emergency, general hospitalization, radiology, and laboratory departments of four hospitals in Arak (Iran) are reported.&#x0D; Materials and Methods: Electric field strength in the 900 MHz frequency band was obtained using a TES 592 radiometer. Then, SAR induced in the brain, skin, fat and bone tissues were calculated based on equations and the obtained values were compared with the thresholds recommended by the International Commissions.&#x0D; Results: The obtained results showed that the electric field’s mean value was 1.334 V/m which is almost 2.7% of the threshold introduced by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and 2.6% of the threshold adopted by the Institute of Electrical and Electronics Engineers (IEEE). The highest SAR value was 1.6 W/kg for the skin, which is lower than the threshold values presented by ICNIRP (2 W/kg) and IEEE (1.6 W/kg).&#x0D; Conclusion: The findings of the present work show that for both quantities in Arak hospitals the SAR values are less than the thresholds announced by IEEE and ICNIRP committees. To deal with the concerns of the community that is generally caused by a lack of awareness, the executions of educational and public awareness programs are recommended.

Comparison of SAR distribution of hip and knee implantable devices in 1.5T conventional cylindrical-bore and 1.2T open-bore vertical MRI systems.

There is increasing use of open-bore vertical MR systems that consist of two planar RF coils. A recent study showed that the RF-induced heating of a neuromodulation device was much lower in the open-bore system at the brain and the chest imaging landmarks. This study focused on the hip and knee implants and compared the specific absorption rate (SAR) distribution in human models in a 1.2T open-bore coil with that of a 1.5T conventional birdcage coil. Computational modeling results were compared against the measurement values using a saline phantom. The differences in RF exposure were examined between a 1.2T open-bore coil and a 1.5T conventional birdcage coil using SAR in an anatomical human model. Modeling setups were validated. The body placed closed to the coil elements led to high SAR values in the birdcage system compared with the open-bore system. Our computational modeling showed that the 1.2T planar system demonstrated a lower intensity of SAR distribution adjacent to hip and knee implants compared with the 1.5T conventional birdcage system.

Synthesis, characterization and heating efficiency of Gd-doped maghemite (γ-Fe2O3) nanoparticles for hyperthermia application

In this paper, sol-gel technique was used to prepare Gd-doped γ-Fe2O3 nanoparticles and their heating efficiency for magnetic hyperthermia application was investigated. The obtained nanoparticles are characterized by several techniques. The structural properties are performed by X-ray diffraction (XRD), energy-dispersive X-ray spectrometer (EDAX) and X-ray Photoelectron Spectroscopy (XPS), while the morphology is investigated by Transmission electron microscopy (TEM). The magnetic properties and heating ability under an alternating magnetic field are performed by vibrating sample magnetometer (VSM) and magnetherm respectively. XRD, XPS and TEM results confirmed the maghemite (γ-Fe2O3) phase, the presence of Gd ions and crystallinity. VSM hysteresis loops showed a negligible coercive field and remanence suggesting superparamagnetic behavior, which was also confirmed by Langevin method. Heating efficiency under an AC alternating magnetic field measurements showed that doped and un-doped samples display high heating ability and reached magnetic hyperthermia (42 °C) in relatively short times with shorter time (∼2 min) observed for γ-Fe2O3 compared to 6 min for Gd (5%) doped γ-Fe2O3 nanoparticles. The specific absorption rate (SAR) values decreased with increased concentration of Gd but remain considerable for all doped samples (up to 40W/g for Gd (5%)). The high crystallinity, superparamagnetic behavior and good SARs values make these nanoparticles a promising candidate for hyperthermia application.

Effects of mobile phone radiation on buccal mucosal cells based on specific absorption rate: a cross sectional study

Background: The usage of mobile phone had been increased drastically which created a major health concern among the people about the radiation emitted from mobile phones. Hence this study was aimed to evaluate the Micronuclei (MN) frequency in exfoliated oral mucosal cells in high and low mobile users based on Specific absorption rate (SAR) value.Methods: The total of 60 subjects were divided into two major groups: low SAR mobile phone users and high SAR mobile phone users. Further, Subjects who use mobile phone for more than 3 hours a week was considered as high talk time users and less than 3 hours a week was low talk time users. The buccal mucosa cells extracted by slightly scraping the oral cavity with a wooden spatula. For staining, Giemsa stain was used. Micronuclei were evaluated in 1000 cells per individual at the microscope.Results: The result show prolonged talk time may interfere with the development of micronuclei in individuals who use mobile phone for more than 3 hours per week rather than high SAR value showing a significant increase in frequency of micronuclei formation.Conclusions: The study showed mobile phone radiation had adverse effects on buccal mucosal cells.

Data Mining of MR Technical Parameters

Exposure to radiofrequency (RF) energy during a magnetic resonance imaging exam is a safety concern related to biological thermal effects. Estimation of the specific absorption rate (SAR) is done by manufacturer scanner integrated tools to monitor RF energy. This work presents an exploratory approach of DICOM metadata focused in whole-body SAR values, patient dependent parameters, and pulse sequences. Previously acquired abdominopelvic and head studies were retrieved from a 3 Tesla scanner. Dicoogle tool was used for metadata indexing, mining, and extraction. Specifically weighted pulse sequences were related with weight, BMI, and gender through boxplot diagrams and effect size analysis. A decrease of SAR values with increasing body weight and BMI categories is observable for abdominopelvic studies. Head studies showed different trends regarding distinct pulse sequences; in addition, underage patients register higher SAR values compared to adults. Male individuals register marginally higher SAR values. Metadata recording practices and standardization need to be improved.

Environmentally friendly magnetic chitosan nano-biocomposite for Cu(II) ions adsorption and magnetic nano-fluid hyperthermia: CCD-RSM design

Chitosan conjugated superparamagnetic iron oxide nanoparticle stabilized citric acid (SPION-CA-CH) nano-biocomposite was fabricated in three synthetic steps; Synthesis of SPION, SPION's surface stabilization with citric acid, and its surface modification with chitosan via carbodiimide chemical reaction. This chemical binding has made it an environmentally clean and biocompatible candidate for magnetically targeting applications. The high performance of the SPION-CA-CH examined through two applications; first, performing as a nano-adsorbent for adsorption of Cu(II) ions as a heavy metal model, and secondly, as targeted nano-heaters for magnetic nano-fluid hyperthermia (MNFH). RSM applied for optimizing and modeling parameters. From the RSM model, the optimum experimental conditions to achieve 91.3% removal of Cu(II) ions were at pH 6.54, nano-adsorbent concentration 0.92 g L−1, and contact time 65.7 min. The maximum Langmuir adsorption capacity was 232.55 mg g−1 (R2=0.9992). Besides, the equilibrium data were well described, with the pseudo-second-order kinetic (R2=0.9993). Desorption studies displayed that the adsorption capacity of prepared nano-adsorbent decreased 12.5% after five times reuse, indicating efficient recovery of the nano-adsorbent for practical application. Apart from the adsorption application, we evaluated the potential of the SPION-CA-CH for MNFH. Optimum conditions for a maximum specific absorption rate (SAR) of 184.40 W g−1 were at 27 kA m−1 and the nano-heater concentration of 1.00 mg mL−1. All in all, the high magnetic response (Ms=60.4 emu g−1), adsorption capacity, reusability, and SAR value, make SPION-CA-CH a potential magnetic nano-adsorbent in wastewater treatment and nano-heaters for MNFH treatment technology.

MRI Guided Magneto-chemotherapy with High-Magnetic-Moment Iron Oxide Nanoparticles for Cancer Theranostics

Elevating and monitoring the temperature of tumors using magnetic nanoparticles (MNPs) still presents a challenge in magnetic hyperthermia therapy. The efficient heating of tumor volume can be achieved by preparing MNPs with high magnetization values. The next-generation approach to magnetic resonance image (MRI)-guided magneto-chemotherapy of cancer based on high-magnetic-moment iron oxide nanoparticles is proposed. The proof of concept is validated by cellular MRI experiments on breast cancer cells. To explore magneto-chemotherapy, we developed high-magnetic-moment iron oxide (Fe3O4) nanoparticles (NPs) using base diisopropylamine (DIPA), which plays a dual role as reducing agent and surface stabilizer. Spherical NPs with ∼12 nm size and a high magnetization value of about 92 emu g-1 at room temperature are obtained by this unique method. A high specific absorption rate value of ∼717 wg-1 was obtained for Fe3O4 NPs in water at an alternating magnetic field of 20 kAm-1 and frequency of 267 kHz, which is attributed to the high magnetization value. The magneto-polymeric micelle structure is formed by using Pluronic F127, and anticancer drug doxorubicin is conjugated in the micelle by electrostatic interactions for magneto-chemotherapy. Finally, the magnetic resonance imaging (MRI)-guided magneto-chemotherapy was achieved on breast cancer (MCF7) cells with an overall ∼96% killing of cancer cells attained in 30 min of magneto-chmeotherapy.

Synthesis and Characterization of Oleic Acid Coated Magnetic Nanoparticles for Hyperthermia Applications

In this study, we aimed to synthesize stable dispersions of iron oxide nanoparticles (IONs) coated with different amounts of oleic acid (OA) suitable for magnetic nano hyperthermia applications. For this purpose, bare and different amounts of oleic acid (0.2%, 0.5% and 1.0%, v/v) coated IONs were prepared by co-precipitation method. Then, their structures, morphologies, magnetic properties and heating abilities were characterized by using suitable techniques. IONs+1.0%OA nanoparticles showed low agglomeration with high dispersion capacity. Moreover, 1.0% OA coating showed the highest heating ability with a temperature increase of (25.2 °C) compared to IONs+OA (0.2%, 16.4 °C; 0.5%, 19 °C), but similar with bare IONs (26.7 °C). The specific absorption rate (SAR) values of bare IONs and IONs+OA (0.2%, 0.5%, 1.0% v/v) were found as 39.50, 34.81, 23.36 and 45.98 W/g, respectively. Our results showed that the comparable hyperthermia effect of IONs+1.0%OA with bare IONs was attributable to their uniform dispersion performance along with higher SAR values. We concluded that the dispersion of hydrophobic IONs+OA in an aqueous medium is one of the critical requirements for increasing temperature in magnetic nano hyperthermia applications.

Numerical Analysis of Human Cancer Therapy Using Microwave Ablation

Microwave ablation is one type of hyperthermia treatment of cancer that involves heating tumor cells. This technique uses electromagnetic wave effects to kill cancer cells. A micro-coaxial antenna is introduced into the biological tissue. The radiation emitted by the antenna is absorbed by the tissue and leads to the heating of cancer cells. The diffuse increase in temperature should reach a certain value to achieve the treatment of cancer cells but it should be less than a certain other value to avoid damaging normal cells. This is why hyperthermia treatment should be carefully monitored. A numerical simulation is useful and may provide valuable information. The bio-heat equation and Maxwell’s equations are solved using the finite element method. Electro-thermal effects, temperature distribution profile, specific absorption rate (SAR), and fraction of necrotic tissue within cancer cells are analyzed. The results show that SAR and temperature distribution are strongly affected by input microwave power. High microwave power causes a high SAR value and raises the temperature above 50 °C, which may destroy healthy cells. It is revealed that with a power of 10 W, the tumor cells will be killed without damaging the surrounding tissue.

Abstract 688: Safety and efficacy of TTFields delivery to the lungs: A computational study

Abstract Objective: This study investigates the efficacy and safety of Tumor Treating Fields (TTFields) delivery to the lungs utilizing computational simulations. Introduction: Recent results of a phase 2 clinical trial STELLAR (NCT02397928) demonstrated a significant extension in median overall survival among patients with mesothelioma treated with TTFields plus standard of care chemotherapy compared to historical control data of patients who received standard of care chemotherapy alone. A phase 3 clinical trial (NCT02973789) is currently investigating the efficacy of TTFields therapy for the treatment of Non-Small-Cell lung cancer (NSCLC). The efficacy of TTFields therapy in disrupting tumor cells depends on the frequency of the field (150kHz optimal frequency for NSCLC and mesothelioma) and the field intensity. The higher the field intensity, the larger the therapeutic effect, with a therapeutic threshold of 0.7 V/cm above which TTFields begin to exert a significant anti-mitotic effect on cells. Delivery of an electric field to the body unavoidably leads to deposition of heat in the tissue through Joule heating. The rate at which electrical energy is absorbed and converted to heat, depends on field’s frequency and tissue’s properties. Since Joule heating may cause thermal damage, it is important to ensure that TTFields intensity in the body is below the thermal damage threshold. In this study we performed numerical simulations to evaluate the thermal safety and the efficacy of the NovoTTF-100L when delivering Tumor Treating Fields to the torso. Thermal safety threshold levels were determined by current density and specific absorption rate (SAR) and TTFields therapeutic threshold was determined by field intensity. Methods: We investigated field intensity, current density and SAR values that developed within 3 different realistic human computational models in which a virtual representation of the NovoTTF-100L (150kHz) was used to deliver TTFields to the lungs. The models used in this study include: a female model, male model and an obese male model (Virtual Population, IT’IS foundation) with a range of BMI values from normal to obese. Numerical simulations were performed using Sim4life (v3.0, ZMT Zurich). Results: The simulations show that for all models, the NovoTTF-100L delivers therapeutic intensities of over 0.7 V/cm RMS to over at least 76% of the lungs. Current density within the models is well below the safety threshold of 100 mA/cm^2. SAR values within the internal organs are below the levels at which thermal damage occurs. In the superficial body layers, higher SAR values are observed. However, the NovoTTF-100L incorporates temperature control that prevents the skin from heating to levels at which thermal damage can occur. Conclusions: Results of this study support the observations that the NovoTTF-100L delivers TTFields to the lungs at therapeutic levels and that the device is safe for use in the entire patient population. Citation Format: Hadas Sara Hershkovich, Noa Urman, Ariel Naveh, Zeev Bomzon. Safety and efficacy of TTFields delivery to the lungs: A computational study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 688.

Simultaneous multi-slice MR imaging of the hip at 3\u2009T to reduce acquisition times and maintain image quality

BackgroundNewly developed simultaneous multi-slice (SMS) scans are now being introduced as a clinical application in neuroimaging. We examined the feasibility of SMS scans for joint imaging. The purpose of the present study was to prospectively compare the resolution and specific absorption rate (SAR) obtained using SMS to those of conventional methods in hip joint magnetic resonance imaging (MRI) and establish whether imaging times may be reduced using SMS in 3 T MRI and if image quality is affected.MethodsTwenty-one patients (4 men and 17 women, average age, 51.5 years, range: 22 to 76 years) with hip pain underwent MR examinations of the unilateral hip joint. Three board-certified radiologists independently and blindly evaluated the images obtained with and without SMS using window and level settings and magnification according to personal preferences. Individual SAR values were measured for each protocol. A Wilcoxon signed-rank test and a t-statistic test were used for statistical analyses. Signal-to-noise ratio (SNR) was also compared using a phantom.ResultsSMS imaging maintained equivalent image quality to conventional imaging for evaluating the morphology of the hip joint, and also reduced imaging times by approximately 40%. SMS images had significantly higher SAR values than conventional images. The rate of difference (SMS/conventional) in SNR ranged between 80 and 111%.ConclusionsBased on its significantly lower acquisition times and the maintenance of similar image quality to conventional imaging, SMS may be applied to morphological evaluations of hip joint disorders without significantly increasing SAR.