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Open access

Ciprian A. Sporea

Abstract

In this paper we study the Dirac equation in the geometry of a (regular) Bardeen black hole. We will focus on finding new analytical solutions in the vicinity of the black hole horizon. These solutions can be used with the asymptotic solutions (derived in a previous paper) to compute numerical phase shifts that define the scattering amplitudes.

Open access

Toshizo Katsuda, Rumi Gotanda, Tatsuhiro Gotanda, Takuya Akagawa, Nobuyoshi Tanki, Tadao Kuwano, Atsushi Noguchi and Kouichi Yabunaka

Abstract

The strength and density change of the ultraviolet (UV) ray of Gafchromic EBT2 were investigated. Previous studies suggested that UV-A rays can be substituted for the x-ray double-exposure technique to correct Gafchromic EBT2’s non-uniformity error. In this study, we aimed to determine the appropriate strength of UV-A rays for irradiating an active layer that would correct the non-uniformity error of Gafchromic EBT2.

UV-A rays with a wavelength of 375 nm were used to irradiate Gafchromic EBT2 in various durations, and the resulting density change was investigated. To correct Gafchromic EBT2’s non-uniformity error, a pre-irradiation with a UV-A lamp was conducted at a distance of 72 cm for 30 min. To determine the most appropriate irradiation duration, a UV light-emitting diode generating UV-A of 375 nm was used to irradiate the Gafchromic EBT2 film with varying durations of 1, 2, 3, 4, 5, 10, 15, 20, 25, and 30 min at a distance of 5.3 cm. A 12.7 diameter region of interest was set by the irradiation area, and a histogram of pixel values was created. The condition options were decided based on two important requirements: 1) no zero values of the mode and seconds exist, and 2) the 1/10 value of the mode intersects both histogram sleeves.

In the case of Gafchromic EBT2, the irradiation strength was 85.43 mJ/cm2 for one minute in which the pixel value of mean ± SD was 255.34 ± 213.29. The irradiation duration of 4 min was the border duration of the above two conditions. When a UV ray of 375 nm wavelength is used to irradiate Gafchromic EBT2 as a substitute for x-ray exposure, the 4-min pre-irradiation duration (341.74 mJ/cm2) is demonstrably sufficient.

Open access

Iroanya Onyekachi Ogbonnaya, Egwuatu Tochukwu Frank, Sonaike Adeola Olasubomi and Uwaezuoke Nduka David

Abstract

Identification of dismembered bodies recovered in disasters or crime scene is very important in forensic. This study was carried out to ascertain if foot size, body weight, height, stature and BMI can be used to predict sex using tape rule and Stadiometer scale. 150 subjects between 18 - 25yrs were recruited. Independent T-test, Pearson Correlation, Linear and Multiple Regression Analysis were determined using SPSS version 23. All measurements were higher in male than female and there was significant (p≤0.05) difference in the sex. The average foot length of 257.39mm was used to determine sex of the subjects. All foot lengths ≤ 257.39mm were presumed to belong to females while all values > 257.39mm was presumed males. Foot size and weight had the highest correlation values. Foot length gave better estimation of sex than foot breadth, BMI and weight. Results of Multiple regression equation was better than linear regression equation. In forensic anthropology, foot size has been used to predict sex. Limitation of this study is the formulae generated can only be applied to Nigerians aged 18-25 yrs. Studies should be carried out on diverse population for future inferences

Open access

Aysan Mohammad Namdar, Mohammad Mohammadzadeh, Murat Okutan and Asghar Mesbahi

Abstract

A review on the radiobiological modeling of radiation-induced hypothyroidism after radiation therapy of head-and-neck cancers, breast cancer, and Hodgkin’s lymphoma is presented. The current review is based on data relating to dose-volume constrains and normal tissue complication probability (NTCP) as a function of either radiobiological or (pre)treatment-clinical parameters. Also, these data were explored in order to provide more helpful criteria for radiobiological optimization of treatment plans involving thyroid gland as a critical normal organ.

Open access

G. Mecheri, S. Hafsi and N. Gherraf

Abstract

The objective of the present work is to prepare and characterize a porous material using quite particular and localized dunar sand (erg) of the desert near the El-Oued (south-east of Algeria). The porous material is prepared according to the mechanism of co-operative self-assembly. The method consists of polymerizing a silicic precursor (sodium silicate obtained by alkali fusion of sand with the sodium carbonate) around micelles of surfactant in an acid aqueous solution according to the sol-gel process. The elimination of the surfactant by calcining at high temperature leads to the final material which was characterized by XRF, XRD, MEB-EDX, FTIR and BET techniques.

Open access

Djamila Maanani, Narimane Segueni, Salah Rhouati, Yavuz Selim Çakmak, Maltem Asan-Ozusaglam, Abdghani May, Amar Zellagui and Salah Akkal

Abstract

This study was carried out to determine the phenolic contents as well as to evaluate the antioxidant and antimicrobial activities of Genista microcephala. Total phenolic and flavonoid compounds were quantified. Antioxidant activity was evaluated by various in vitro tests, including Ferric Ion Reducing Activity (FRP), Cuprac Ion Reducing Antioxidant Capacity (CUPRAC), and total antioxidant capacities (TAC). The antimicrobial activity of ethyl acetate and butanolic extracts of G. microcephala in addition of fatty acids content of different parts of the studied plant was evaluated against human pathogenic bacteria, fish bacteria and two yeast. The used methods were agar diffusion method and the determination of minimal bactericidal and fungicidal concentrations (MBC and MFC). No significant difference was found between the two used solvents on total phenolic content (TPC). While, difference in total flavonoid content (TFC) were found to be significant. Ethylene acetate extract was the most actif regarding antioxidant assay. The tested activity seems to be due to the high content of this extract on isoflavonoids. The tested extracts demonstrated the lowest inhibition concentration for B.cereus RSKK 863.

Open access

Bilalodin, Kusminarto, Gede Bayu Suparta, Arief Hermanto, Dwi Satya Palupi and Yohannes Sardjono

Abstract

The genetic algorithm method is a new method used to obtain radiation beams that meet the IAEA requirements. This method is used in optimization of configurations and compositions of materials that compose double layered Beam Shaping Assembly (BSA). The double layered BSA is modeled as having two layers of material for each of the components, which are the moderator, reflector, collimator, and filter. Up to 21st generation, the optimization results in four (4) individuals having the capacity to generate the most optimum radiation beams. The best configuration, producing the most optimum radiation beams, is attained by using combinations of materials, that is by combining Al with either one of CaF2 and PbF2for moderator; combining Pb material with either Ni or Pb for reflector; combining Ni and either FeC or C for collimator, and FeC+LiF and Cd for fast and thermal neutron filter. The parameters of radiation resulted from the four configurations of double layer BSA adequately satisfy the standard of the IAEA.

Open access

Samuel N. A. Tagoe, Samuel Y. Mensah and John J. Fletcher

Abstract

Objectives: The present study aimed to generate intensity-modulated beams with compensators for a conventional telecobalt machine, based on dose distributions generated with a treatment planning system (TPS) performing forward planning, and cannot directly simulate a compensator.

Materials and Methods: The following materials were selected for compensator construction: Brass, Copper and Perspex (PMMA). Boluses with varying thicknesses across the surface of a tissue-equivalent phantom were used to achieve beam intensity modulations during treatment planning with the TPS. Beam data measured for specific treatment parameters in a full scatter water phantom with a 0.125 cc cylindrical ionization chamber, with a particular compensator material in the path of beams from the telecobalt machine, and that without the compensator but the heights of water above the detector adjusted to get the same detector readings as before, were used to develop and propose a semi-empirical equation for converting a bolus thickness to compensator material thickness, such that any point within the phantom would receive the planned dose. Once the dimensions of a compensator had been determined, the compensator was constructed using the cubic pile method. The treatment plans generated with the TPS were replicated on the telecobalt machine with a bolus within each beam represented with its corresponding compensator mounted on the accessory holder of the telecobalt machine.

Results: Dose distributions measured in the tissue-equivalent phantom with calibrated Gafchromic EBT2 films for compensators constructed based on the proposed approach, were comparable to those of the TPS with deviation less than or equal to ± 3% (mean of 2.29 ± 0.61%) of the measured doses, with resultant confidence limit value of 3.21. Conclusion: The use of the proposed approach for clinical application is recommended, and could facilitate the generation of intensity-modulated beams with limited resources using the missing tissue approach rendering encouraging results.

Open access

Hideharu Miura, Shuichi Ozawa, Tsubasa Enosaki, Masahiro Hayata, Kiyoshi Yamada and Yasushi Nagata

Abstract

We investigated the gantry-angle classifier performance with a fluence map using three machine-learning algorithms, and compared it with human performance. Eighty prostate cases were investigated using a seven-field-intensity modulated radiotherapy treatment (IMRT) plan with beam angles of 0°, 50°, 100°, 155°, 205°, 260°, and 310°. The k-nearest neighbor (k-NN), logistic regression (LR), and support vector machine (SVM) algorithms were used. In the observer test, three radiotherapists assessed the gantry angle classification in a blind manner. The precision and recall rates were calculated for the machine learning and observer test. The average precision rate of the k-NN and LR algorithms were 94.8% and 97.9%, respectively. The average recall rate of the k-NN and LR algorithms were 94.3% and 97.9%, respectively. The SVM had 100% precision and recall rates. The gantry angles of 0°, 155°, and 205° had an accuracy of 100% in all algorithms. In the observer test, average precision and recall rates were 82.6% and 82.6%, respectively. All observers could easily classify the gantry angles of 0°, 155°, and 205° with a high degree of accuracy. Misclassifications occurred in gantry angles of 50°, 100°, 260°, and 310°. Machine learning could better classify gantry angles for prostate IMRT than human beings. In particular, the SVM algorithm had a perfect classification of 100%.

Open access

Nikolay Uzunov, Michele Bello, Laura Melendez-Alafort and Laura De Nardo

Abstract

In recent years, there is a constantly increasing interest in the application of nanoparticles for cancer diagnosis and cancer therapy. In this respect, the most promising nano-objects at present are the gold nanoparticles. A very convenient and powerful property of these objects is their ability to increase their temperature under electro-magnetic irradiation with certain wavelength. In our research we have directed our efforts toward particular nano-objects specifically sensitive to electromagnetic radiation in the near-infrared region (NIR). In order to study the photothermic properties of the solutions of gold nanoparticles in the NIR we constructed a specific electronic setup consisting of a laser system with interchangeable laser diodes with different wavelength NIR light, a thermally-insulated cuvette-holder compartment with temperature measuring probes and a NIR spectrometer to control the stimulated fluorescence emission of the nanoparticles’ solutions. The temperature measurement compartment with the thermal-insulated cuvette holder was designed to maintain the solutions’ temperature at a fixed value right before the moment of laser irradiation. To maintain the measurement setup at a fixed temperature before the irradiation we used a thermal stabilized system based on two Peltier cells with electronic temperature control. The temperatures of the ambient air and the temperature of the cuvette walls were continuously measured in order to make corrections about the temperature dissipation during the irradiation.