Modeling of Interstitial Microwave Hyperthermia for Hepatic Tumors Using Floating Sleeve Antenna

PurposeMicrowave hyperthermia is a treatment modality that uses microwaves to destroy cancer cells by increasing their temperature to 41- 45°C. This study aims to design, modeling, and simulation of a microwave sleeve antenna for hepatic (liver) hyperthermia. MethodThe designed antenna resonated at 2.45 GHz. The antenna was tested in six different 3D liver models: Model A: without a tumor and blood vessels; Model B: with a realistic tumor (2x3 cm) and without blood vessels; Model C: created by adding blood vessels to model B; Model D: created by adding a small tumor (1.5x1.5 cm) to model C and changed its location; Model E: same as model C with a different tumor size; Model F: model with a simple spherical tumor (1.5x1.5 cm).ResultsThe return loss of the antenna varied from -45 dB to -25 dB for the 6 models. The Specific Absorption Rate (SAR) was between 29 W/kg to 30W/kg in the tumors and below 24 W/Kg in the surrounding tissues. The tumors’ temperature elevated to 43- 45°C, while the temperature of the surrounding tissues was below 41°C.ConclusionsThe results showed the capability of the designed antenna to raise the temperature of hepatic tumors to the therapeutic ranges of hyperthermia.

A Computational Study on Magnetic Nanoparticles Hyperthermia of Ellipsoidal Tumors

The modelling of magnetic hyperthermia using nanoparticles of ellipsoid tumor shapes has not been studied adequately. To fill this gap, a computational study has been carried out to determine two key treatment parameters: the therapeutic temperature distribution and the extent of thermal damage. Prolate and oblate spheroidal tumors, of various aspect ratios, surrounded by a large healthy tissue region are assumed. Tissue temperatures are determined from the solution of Pennes’ bio-heat transfer equation. The mortality of the tissues is determined by the Arrhenius kinetic model. The computational model is successfully verified against a closed-form solution for a perfectly spherical tumor. The therapeutic temperature and the thermal damage in the tumor center decrease as the aspect ratio increases and it is insensitive to whether tumors of the same aspect ratio are oblate or prolate spheroids. The necrotic tumor area is affected by the tumor prolateness and oblateness. Good comparison is obtained of the present model with three sets of experimental measurements taken from the literature, for animal tumors exhibiting ellipsoid-like geometry. The computational model enables the determination of the therapeutic temperature and tissue thermal damage for magnetic hyperthermia of ellipsoidal tumors. It can be easily reproduced for various treatment scenarios and may be useful for an effective treatment planning of ellipsoidal tumor geometries.

Modeling of Interstitial Microwave Hyperthermia for Hepatic Tumors Using Floating Sleeve Antenna

Background: Liver tumor, also known as hepatic tumor is one of the most common cancers with 80% of cases occurs in developing countries. Microwave hyperthermia is one of the promising treatment modalities that use microwaves to destroy the cancer cells by rising their temperature to 41- 45°C. This temperature elevation is achieved by using an applicator such as antennas. This study aims to design a microwave sleeve antenna capable of heating hepatic tumors (with different sizes and locations) to the therapeutic range of temperature for hyperthermia. Method: The sleeve antenna was designed to be resonate at 2.45 GHz and tested in a free space. Then; the antenna was tested in 6 different 3D liver models: Model A: without a tumor or blood vessels, Model B: with a tumor (2B3cm) and without blood vessels, Model C: created by adding blood vessels to model B, then a small tumor (1.5a1.5cm) was created and its location (Model D) and size (Model E) were changed. Finally, a model with a spherical tumor of 1.5 cm diameter (Model F) was tested. Results: The return loss (S-parameters) of the antenna was varied from -45 dB to -25 dB in the different liver models. The Specific Absorption Rate (SAR) reached 30W/kg in the tumor and less than 24 W/kg in the surrounding tissues, while the tumor temperature elevated to the therapeutic ranges of hyperthermia in the all models and the surrounding tissues remain at a safe temperature range. Conclusions: The obtained results showed the capability of the designed antenna to raise the temperature of hepatic tumors to the therapeutic ranges of hyperthermia.

Evaluation of FET PET Radiomics Feature Repeatability in Glioma Patients

Amino acid PET using the tracer O-(2-[18F]fluoroethyl)-L-tyrosine (FET) has attracted considerable interest in neurooncology. Furthermore, initial studies suggested the additional diagnostic value of FET PET radiomics in brain tumor patient management. However, the conclusiveness of radiomics models strongly depends on feature generalizability. We here evaluated the repeatability of feature-based FET PET radiomics. A test–retest analysis based on equivalent but statistically independent subsamples of FET PET images was performed in 50 newly diagnosed and histomolecularly characterized glioma patients. A total of 1,302 radiomics features were calculated from semi-automatically segmented tumor volumes-of-interest (VOIs). Furthermore, to investigate the influence of the spatial resolution of PET on repeatability, spherical VOIs of different sizes were positioned in the tumor and healthy brain tissue. Feature repeatability was assessed by calculating the intraclass correlation coefficient (ICC). To further investigate the influence of the isocitrate dehydrogenase (IDH) genotype on feature repeatability, a hierarchical cluster analysis was performed. For tumor VOIs, 73% of first-order features and 71% of features extracted from the gray level co-occurrence matrix showed high repeatability (ICC 95% confidence interval, 0.91–1.00). In the largest spherical tumor VOIs, 67% of features showed high repeatability, significantly decreasing towards smaller VOIs. The IDH genotype did not affect feature repeatability. Based on 297 repeatable features, two clusters were identified separating patients with IDH-wildtype glioma from those with an IDH mutation. Our results suggest that robust features can be obtained from routinely acquired FET PET scans, which are valuable for further standardization of radiomics analyses in neurooncology.

Lyapunov stability of competitive cells dynamics in tumor mechanobiology

Poromechanics plays a key role in modelling hard and soft tissue behaviours, by providing a thermodynamic framework in which chemo-mechanical mutual interactions among fluid and solid constituents can be consistently rooted, at different scale levels. In this context, how different biological species (including cells, extra-cellular components and chemical metabolites) interplay within complex environments is studied for characterizing the mechanobiology of tumor growth, governed by intratumoral residual stresses that initiate mechanotransductive processes deregulating normal tissue homeostasis and leading to tissue remodelling. Despite the coupling between tumor poroelasticity and interspecific competitive dynamics has recently highlighted how microscopic cells and environment interactions influence growth-associated stresses and tumor pathophysiology, the nonlinear interlacing among biochemical factors and mechanics somehow hindered the possibility of gaining qualitative insights into cells dynamics. Motivated by this, in the present work we recover the linear poroelasticity in order to benefit of a reduced complexity, so first deriving the well-known Lyapunov stability criterion from the thermodynamic dissipation principle and then analysing the stability of the mechanical competition among cells fighting for common space and resources during cancer growth and invasion. At the end, the linear poroelastic model enriched by interspecific dynamics is also exploited to show how growth anisotropy can alter the stress field in spherical tumor masses, by thus indirectly affecting cell mechano-sensing. GraphicAbstract

I. Finzi. А case of osteoma of the pelvis, causing dystocia. (Lancet., 1894, Juli 14, No. 3698, p. 77). Bone swelling in the pelvis as a cause of abnormal labor.

Dr. F. was invited to 28-year-old first women on 16 / VI 94 g. During examination through the vagina, F. felt a wide, smooth spherical tumor of bone hardness protruding into the right anterior part of the pelvic cavity, giving the impression of a presenting head.

Supratentorial convexity schwannoma unrelated to cranial nerves: Case report and review of the literature

Background: Intracranial schwannoma not related to cranial nerves is rare entity, and difficult to be diagnosed preoperatively. Here, we experienced a case of convexity schwannoma mimicking convexity meningioma, and discuss about the characteristics of such cases based on the past published reports. Case Description: A 48-year-old man presented with a sudden onset of seizures. Brain magnetic resonance image (MRI) revealed a small mass lesion in the peripheral aspect of the right parieto-frontal lobe. The mass was isointense on T1-weighted and hyperintense on T2-weighted MRI, with homogenous enhancement after contrast medium administration. After the feeder embolization on the previous day, removal of the tumor was performed. The tumor revealed a well-demarcated, firm, spherical tumor beyond, and beneath the dura and was relatively easy to be separated from the brain. Histologically, the tumor was observed to be in subarachnoid space extending to outer space of dura-mater, intimately attached to the pia mater. The histological diagnosis was schwannoma. Conclusion: In our case, MRI findings are similar to convexity meningioma; however, the pathological diagnosis was schwannoma. Cerebral convexity is an extremely rare location for schwannoma. We emphasize that schwannoma, not related to cranial nerves, may arise in the subdural convexity space.

Nucleation of antagonistic organisms and cellular competitions on curved, inflating substrates

We consider the dynamics of spatially-distributed, diffusing populations of organisms with antagonistic interactions. These interactions are found on many length scales, ranging from kilometer-scale animal range dynamics with selection against hybrids to micron-scale interactions between poison-secreting microbial populations. We find that the dynamical line tension at the interface between antagonistic organisms suppresses survival probabilities of small clonal clusters: the line tension introduces a critical cluster size that an organism with a selective advantage must achieve before deterministically spreading through the population. We calculate the survival probability as a function of selective advantage δ and antagonistic interaction strength σ. Unlike a simple Darwinian selective advantage, the survival probability depends strongly on the spatial diffusion constant Ds of the strains when σ > 0, with suppressed survival when both species are more motile. Finally, we study the survival probability of a single mutant cell at the frontier of a growing spherical cluster of cells, such as the surface of an avascular spherical tumor. Both the inflation and curvature of the frontier significantly enhance the survival probability by changing the critical size of the nucleating cell cluster.

A comparison of arrived dose to the heart in the treatment of breast cancer in different modes of proton radiation by proton therapy using Monte Carlo simulation

Introdution: Today, the Advantages of radiation therapy by charged particles is indicated for the treatment of cancerous. During the passing of proton beam in the body tissues, secondary particles produce, which penetrate to the body healthy tissues and cause damage. The aim of this research was calculating the Spread out Bragg Peak for covering the breast cancer and investigating arrived dose to the different parts of the heart during the treatment process. Methods: In this simulation study, a spherical tumor with a diameter of 1 cm considered in right breast tissue in MIRD phantom and then irradiated by proton of right and front sides of the body. Simulations are performed using the MCNPX code. Results: The Spread out Brag Peak calculated to cover the breast cancer in two cases of radiation. In the radiation of front and right, the deposited Dose due to The Proton Particle in tumor are 4.25 nGy and 4.12 nGy, respectively. The dose due to the protons and secondary particles in different parts of the heart calculated and compared for two modes of radiation. Energy Ranges of neutrons was about 55 MeV and for electrons and photons was less than 20 MeV. Although, the dose due to the secondary particles was very low in comparison of protons dose. Conclusion: In proton therapy, a large portion of the dose is evacuated in the tumor. Proton radiation of the front in comparison of the right leads to the more dose deposit in the tumor and heart.