Different Methods of Measuring Neutron Dose/Fluence Generated During Radiation Therapy with Megavoltage Beams

Medical linear accelerators (linacs) are the most frequently applied radiation therapy machines in the locoregional treatment of cancers by producing either high-energy electron or photon beams. However, with high-energy photons (>8 MeV), interaction of these photons with different high-Z nuclei of materials in components of the linac head unavoidably generates neutrons. On the other hand, the average energy of these generated neutrons has almost the highest radiation-weighting factor. Therefore, the produced neutrons should not be neglected. There are various tools for the measurement of neutron dose/fluence generated in a megavoltage linac, including thermoluminescent dosimeters, solid-state nuclear track detectors, bubble detectors, activation foils, Bonner sphere systems, and ionization chamber pairs. In this review article, each of the above-mentioned dosimetric methods will be described in detail

Quantitative Cytotoxicity, Cellular Uptake and Radioprotection Effect of Cerium Oxide Nanoparticles in MRC-5 Normal Cells and MCF-7 Cancerous Cells

Optimal distribution of cerium oxide nanoparticles (CONPs) or nanoceria can have a significant impact on their cytotoxicity, cellular uptake, and radioprotection effects. In this study, two different distribution plans of CONPs were investigated. A scanner electron microscope (SEM) was used for chemical analysis and recording of CONP images. Using MTT assay, the non-toxic concentrations of nanoceria with two different distribution plans were determined in MRC-5 and MCF-7 cell lines. Nanoceria cellular uptake at 50, 150, and 250 μM with two different dispersion plans was determined by using the UV/VIS absorbance of cell culture medium after 24 h of incubation. In order to quantify radioprotection effect, cells treated with non-toxic concentrations of nanoceria were exposed to 10, 40, and 100 cGy of 6 MV photon beams. The diameter of the spherical CONPs was 29 nm. Energy dispersive spectroscopy analysis showed that the cerium element has the highest weight percentage in CONPs (97.9). Accumulation rate of filtered and non-filtered suspension were determined as 0.3608 and 14.2708 μg/ml/h, respectively. The 70 and 110 μM concentration of sustained nanoceria suspension did not have any toxicity for MRC-5 and MCF-7 cells, respectively. In both cell lines, 50, 150, and 250 μM of filtered nanoceria had a significant uptake than the non-filtered nanoceria. A total of results showed that the 70 μM of nanoceria have a significant radioprotection on normal cells in the radiation dose of 40 and 100 cGy, while the highest cellular uptake of nanoceria occurred in cancer cells. The results suggest that using of stable distribution of CONPs for radiation protection could be a good choice, knowing that these nanostructures will have selective protection in normal cells. © 2018, Springer Science+Business Media, LLC, part of Springer Nature

Estimation of radiation dose-reduction factor for cerium oxide nanoparticles in MRC-5 human lung fibroblastic cells and MCF-7 breast-cancer cells

In the current study, radiation dose-reduction factor (DRF) of nanoceria or cerium oxide nanoparticles (CONPs) in MRC-5 Human Lung Fibroblastic Cells and MCF-7 Breast-Cancer Cells was estimated. Characterization of CONPs was determined using scanner electron microscope (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and spectrophotometer. Then, six plans were designed with different radiation dose values on planning target value. The obtained MRC-5 and MCF-7 cells were treated with non-toxic concentrations of CONPs and then exposed. Finally, cell viability () of the cell lines was determined using MTT assay. The findings showed that CONPs have no significant radioprotective effect against 10 cGy radiation dose value. Nevertheless, 70 μM CONPs resulted in a significant radioprotection against 100, 200, 300, 400 and 500 cGy radiation dose values compared with the control group in MRC-5 cells. For all radiation dose values, mean cell viability () of MCF-7 had not increased significantly at the presence of nanoceria compared with control group. According to the findings, it was revealed that the use of CONPs have a significant radioprotective effect on normal lung cells, while they do not provide any protection for MCF-7 cancer cells. These properties can help to increase therapeutic ratio of radiotherapy. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group

Analysis of Permanent Magnet Demagnetization Effect Outer-rotor Hybrid Excitation Flux Switching Motor

This paper addresses the irreversible permanent magnet (PM) demagnetization analysis of hybrid excitation flux switching motor (HEFSM) with outer-rotor configuration. PM demagnetization cause the PM strength used in the motor significantly reduces and hence contributes less torque performance. The study is focused on thermal analysis and conducted at various temperature up to as high as 180 degrees Celsius which has a tendency to be demagnetized. Therefore, PM demagnetization is among a critical issue and influences the choice of the applied motor. The analysis is carried out based on finite element method (FEM) and percentage of PM demagnetization is then calculated. Finally, based on simulated and calculated results the final design outer-rotor HEFSM has only 0.85 percent PM demagnetization at very high temperature and obviously the is no PM demagnetization at normal operating conditions

Folic acid functionalized nanoparticles as pharmaceutical carriers in drug delivery systems

Conventional chemotherapeutic approaches in cancer therapy such as surgery, chemotherapy, and radiotherapy have several disadvantages due to their nontargeted distributions in the whole body. On the other hand, nanoparticles (NPs) based therapies are remarkably progressing to solve several limitations of conventional drug delivery systems (DDSs) including nonspecific biodistribution and targeting, poor water solubility, weak bioavailability and biodegradability, low pharmacokinetic properties, and so forth. The enhanced permeability and retention effect escape from P-glycoprotein trap in cancer cells as a passive targeting mechanism, and active targeting strategies are also other most important advantages of NPs in cancer diagnosis and therapy. Folic acid (FA) is one of the biologic molecules which has been targeted overexpressed-folic acid receptor (FR) on the surface of cancer cells. Therefore, conjugation of FA to NPs most easily enhances the FR-mediated targeting delivery of therapeutic agents. Here, the recent works in FA which have been decorated NPs-based DDSs are discussed and cancer therapy potency of these NPs in clinical trials are presented. © 2019 Wiley Periodicals, Inc