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- ItemOpen AccessDesign and Evaluation of Structural Shielding of a Typical Radiotherapy Facility Using EGSnrc Monte Carlo Code(Wolters Kluwer, 2022-03-31) Ibitoye, A. Z.; Adedokun, M. B.; Orotoye, T. A.; Udo, G. B.Purpose: This study aimed to evaluate the shielding integrity of a typical radiotherapy facility using the Monte Carlo (MC) method. Materials and Methods: EGSnrc MC code was used to design a radiotherapy bunker with appropriate materials and thicknesses. A concrete density of 2.36 g/cm3 was used as a shielding material for primary and secondary barriers. The lead slab was used in the entrance door. The complex geometries of the bunker were modeled by using the egs++ application code embedded in the software. Phase‑space generated from a linac machine built with BEAMnrc codes was used as a source of 18 MV X‑ray beam set at 100 cm source–surface distance with a field size of 40 cm × 40 cm. Energy deposited in each geometrical region was evaluated and analyzed. Results: Energy deposited at the entrance door, supervised and controlled areas were found to be approximately 0%. No significant difference in the energy deposition on the geometries was observed when the gantry angles were set at either 90° or 270° (P = 1). Conclusion: The findings in this study revealed that the EGSnrc MC code can be used as a veritable tool in the design and evaluation of structural shielding efficiency in a radiotherapy facility.
- ItemOpen AccessAnalysis of Efficiency of Different Antennas for Microwave Ablation using Simulation and Experimental Methods.(Elsevier, 2018-02-05) Ibitoye, AZ; Orotoye, T; Nwoye, EO; Aweda, MAThe objective of this study is to analyze the efficiency of different antennas proposed for microwave ablation therapy using numerical simulation and experimental approach. The simulation was done with COMSOL MULTIPHYSICS software to design antenna prototypes and evaluate its reflection coefficient, power dissipation distribution, power dissipation density, specific absorption rate and temperature distribution in tissue. Antennas were fabricated from a 50 X RG405/U semi-rigid coaxial cable to match the geometric prototypes generated during simulation. Ex vivo bovine livers were ablated with the fabricated antennas using 50Wfor 5 and 10 min. Ablation diameters, ablation lengths and aspect ratios were determined. Sleeved antenna produced lowest reflection coefficient, high power dissipation, low power dissipation density, high SAR and high temperature in the simulation. Sleeved antenna provides excellent localization, large ablative diameter, low backward heating and high aspect ratio than single slot, dual slot and monopole antennas.
- ItemOpen AccessOverexposure of rats to radiation from infrared lamp: Effects on blood parameters(Wolters Kluwer, 2016-07) Ibitoye, A; Afolabi, O; Irurhe, N; Ekun, O; Sowunmi, ABackground: Previous reports showed that infrared radiation (IR) involved in photoaging, photocarcinogenesis, free radicals’ production, and depletion of bone marrow cells. Beneficial effects of moderate exposure to infrared lamp have been itemized to include enhancement of blood circulation, relief from muscular pain, and wound healing acceleration with scarce information on biological effects when it is overexposed. Therefore, there is a need to investigate the possibility of its overexposure on the biological system, especially blood parameters. Aim: This study was aimed to determine the biological effects of overexposure to radiation from infrared lamp on blood parameters. Materials and Methods: Infrared lamp of 100 W acts as a source of the IR. Twenty male healthy Wistar rats of the age range between 10 and 12 weeks and weigh between 100 and 250 g were studied. All the animals studied also acts as a control group with their blood samples taken and recorded as initial counting values. The animals were later divided into three groups: A, B, and C according to their hours of exposure according to their weight. Animals in Groups A, B, and C were exposed to IR for 1, 3, and 5 h, respectively. Blood samples of each animal in the group were taken 24, 48, and 96 h after exposure. The total number of erythrocytes, leukocytes, lymphocyte, and neutrophils were counted and compared with the initial samples. Results: The results revealed that packed cell volume, white blood cells, and lymphocytes of all the exposed animals averagely decreased by 17.4%, 17.5%, and 11.3%, respectively, whereas neutrophil increased by 19.0% after exposure to infrared. Conclusion: This study established that overexposure to radiation from infrared lamp affects hematological parameters.
- ItemOpen AccessEvaluation of temperature distributions during microwave ablation of ex vivo bovine liver using two types of antennas.(2019-03) Ibitoye, AZ; Nwoye, EO; Saseyi, AO; Adeneye, SO; Adedokun, MB; Aweda, MAIntroduction: Temperature distributions during microwave ablation are dependent on the antenna types, antenna geometry, tissue properties, input power and ablation. All these factors can significantly affect the coagulation region, ablation length, ablation diameter, aspect ratio, backward heating (comic effect), and degree of necrosis. Temperature distributions during microwave ablation procedures determine the effectiveness of ablating tumours in tissue. Objective: The aim of this study is to evaluate temperature distributions during microwave ablation using sleeved and dual slot antennas. Materials and Methods: In this study, sleeved and dual slot antennas were designed using COMSOL MULTIPHYSICS software version 4.4. Temperature distributions were analyzed at 10 mm and 20 mm from the antennas’ surfaces. Dualslot and sleeved antennas were fabricated from 0.085’ 50 Ω semi-rigid coaxial cable to conform to numerical simulation. The antennas were applied on ex vivo bovine liver. Thermometer probes were placed at 10 mm and 20 mm from the antennas’ surfaces with the input powers set at 30, 50 and 80 W for 300 s. Before each ablation, the initial temperature was recorded whereas subsequent measurements were recorded at 50 s intervals. Numerical simulation and experimental obtained data were analyzed and compared using the student's t-test statistical tool. Results: The findings in this study showed that temperatures produced at the two points of measurements by the sleeved antenna were greater than that of the dual-slot antenna in simulation and experimental procedures. Also, there was no significant difference between simulation and experimentally results for dual-slot antenna and sleeved antenna (p = 0.25). Conclusion: In conclusion, the sleeved antenna has the potential to ablate a tumour faster above the tumoricidal temperatures at the same position than the dual-slot antenna.
- ItemOpen AccessMicrowave ablation of ex vivo bovine tissues using a dual slot antenna with a floating metallic sleeve(Taylor and Francis, 2016-08-16) Ibitoye, AZ; Nwoye, EO; Aweda, MA; Oremosu, AA; Annunobi, CC; Akanmu, ONPurpose: To study the efficiency of a dual slot antenna with a floating metallic sleeve on the ablation of different ex vivo bovine tissues. Materials and methods: COMSOL MultiphysicsVR version 4.4 (Stockholm, Sweden), which is based on finite element methods (FEM), was used to design and simulate monopole and dual slot with sleeve antennas. Power, specific absorption rate (SAR), temperature and necrosis distributions in the selected tissues were determined using these antennas. Monopole and dual slot with sleeve antennas were designed, simulated, constructed and applied in this study based on a semi-rigid coaxial cable. Ex vivo experiments were performed on liver, lung, muscle and heart of bovine obtained from a public animal slaughter house. The microwave energy was delivered using a 2.45 GHz solid-state microwave generator at 40 W for 3, 5 and 10 min. Aspect ratio, ablation length and ablation diameter were also determined on ablated tissues and compared with simulated results. Student’s t-test was used to compare the statistically significant difference between the performance of the two antennas. Results: The dual slot antenna with sleeve produces localised microwave energy better than the monopole antenna in all ablated tissues using simulation and experimental validation methods. There were significant differences in ablation diameter and aspect ratio between the sleeve antenna and monopole antenna. Additionally, there were no significant differences between the simulation and experimental results. Conclusions: This study demonstrated that the dual slot antenna with sleeve produced larger ablation zones and higher sphericity index in ex vivo bovine tissues with minimal backward heating when compared with the monopole antenna.