ABSTRACT
The Monte Carlo method can be used to describe any technique that approximates solutions to quantitative problems through statistical sampling. This method is considered to be the most accurate method for dose calculation in radiotherapy. For complete modeling of a linear accelerator, it is required that the manufactured information covers all data, but some data such as primary electron energy must be indicated. The purpose of this study was to determine the best primary electron energy for 15 MV photon beam with varying the energy and FWHM. A Monte Carlo model for photon-beam output of a Siemens primus linear accelerator was validated by plotting the energy spectrum of photon beam and calculating the percentage depth dose [PDD] and beam profiles for 10×10 cm[2] field. Square 10×10 cm[2] field was validated by measurements in water by a farmer chamber. Linac head simulation was performed with BEAMnrc and dose calculation and 3D dose file were produced by DOSXYZnrc. The results were analyzed using MATLAB. It was found a good agreement between calculated PDD and beam profile for 15 MV photon beam using Monte Carlo simulation with primary electron energy of 11 MV and FWHM of 0.4 with maximum dose difference of 1.2% in PDD curves. In conclusion, using primary electron energy of 11 MV and FWHM of 0.4 has very good accuracy in calculating of dose distribution for 15 MV photon beam and it can be considered as a promising method for patient dose calculations
ABSTRACT
Esophageal cancer is one of the most common malignancies with a growing occurrence. It presently ranks ninth among the most frequent cancers in the world and the sixth leading cause of death from cancer. For a variety of reasons, the mainstream of patients with esophageal cancer is actually not suitable for Esophagectomy. More than 50% have locally advanced unresectable or metastatic tumors at diagnosis. Other reasons which exclude Esophagectomy include old age, comorbidity or refusal by the patient. For more advanced stages of esophageal cancers, the basis of non-surgical treatment is chemotherapy [CT] or radiotherapy [RT], either alone or in combination as chemoradiotherapy [CRT]. The purpose of this study is to summaries and judgmentally analyzes current non-surgical treatments. Although the best treatment for locally advanced esophageal cancer is still being debated, the use of neoadjuvant chemoradiotherapy has gained acceptance
ABSTRACT
TiO[2] nanoparticles [NPs] might be considered as the most important photosensitizer due to high photocatalytic and sonocatalytic efficiency, low toxicity, excellent biocompatibility, low cost and high chemical stability. TiO[2]-NPs normally tend to aggregate in physiological medium and which results to decreased cell viability and inducing expression of stress-related genes. Thus dispersion and stability of TiO[2] NPs should be considered in biological application. This paper deals on various dispersing methods such as ultrasonication, electrostatic, steric electrosteric stabilization that suppress agglomeration and stabilizes the dispersed NPs in aqueous medium
Sonication breaks up agglomerated NPs in a solvent. The results showed that probe sonication performs better than bath sonication in dispersing TiO[2] agglomerates, but sonication couldn't prevent long term aggregation of nanoparticles and in order to form stable dispersions, it is not enough to break nanoparticles apart. Agglomerated NPs can be separated by overcoming the weaker attractive forces by electrostatic, steric or electrosteric interactions. Electrostatic stabilization takes place when charges accumulate at the surface of particles. At values of potential more than 30 mV or less than -30 mV no agglomeration occurs. Ionic strength and pH influence on electrostatic stabilization; when pH is far from the isoelectric point, agglomeration is suppressed. In a sterically stabilized dispersion large molecules such as polymers, surfactants and biomolecules, adsorbed on to the surface of particles suppress re-agglomeration. PEG is a hydrophilic polymer, non-toxic and non-immunogenic, and has favorable pharmacokinetics and tissue distribution. PEGylation of NPs not only prevents agglomeration, but also enhances their biocompatibility and increases the in vivo circulation time
ABSTRACT
Extremely low frequency electromagnetic fields [ELF-EMF] have been common in daily life all over the world. They have produced by power lines and electrical appliances, but higher levels of them have raised a lot of concerns about their carcinogenesis. Both epidemiological and laboratory studies have suggested that EMFs might increase cancer incidence, including acute childhood leukemia, brain and breast cancer. In the present study, SH-SY5Y human neuroblastoma cell line has exposed to 2mT, 50 Hz magnetic field for 3 h. Next, effect of this exposure on protein expression including over-expression or under-expression has assessed by proteomics. Bioinformatics and statistical analysis using progenesis same spot software on the obtained 2D electrophoresis has shown that expression of 189 proteins in exposed group has changed relative to control. Besides, PCA analysis has verified results of clustering, and has shown that protein data has clustered according to experimental conditions. The results of this study have shown that ELF-EMF changes cell morphology via altering protein expression, but more profound studies have needed to determine the kind of proteins altered
Subject(s)
Humans , Neuroblastoma , Cell Line , ProteomicsABSTRACT
Previous investigation has shown that Thymus Vulgaris [TV] modulates pain. The aim of this work was to examine the role of TV on acute and chronic pain and compares its effect with dexamethasone [DEX] and stress [ST] by using Hot plate, Tail flick and Formalin tests in mice. In this study male albino mice [25-30 g.] in 21 groups [n = 147] were used. TV [100, 500 and 1000mg/kg], DEX [0.5, 1 and 2 mg/kg] and vehicle [VEH] were injected 30 minutes before pain assessment tests. Stress was applied by 1 min swimming in cold water [18 - 22°]. Acute and chronic pain was assessed by Hot plate, Tail flick and Formalin tests. For assessment of the role of opioid receptors in antinoceception of TV extract, Naloxon [NAL, 2mg/kg, ip] as opioid receptor antagonist was injected before the injection of the more effective dose [500mg/kg] of TV extract. Results indicated that TV, DEX and ST have analgesic effects in all tests [P < 0.01 in comparison with control group]. Above findings showed that TV extract, DEX and ST have modulatory effects on acute and chronic pain. Further research is required to determine the mechanisms by which TV extract has an inhibitory effect on pain sensation