a. kazemzadeh

The main purpose of this study is to investigate different methods of radiotherapy (RT) using coplanar three-dimensional conformal RT (3D-CRT (cp)), non-coplanar 3D-CRT RT (3D-CRT (ncp)) and helical tomotherapy (HT) techniques to find the optimal method to treat gastric cancer patients. 

Twenty patients with gastric cancer were retrospectively enrolled. Three different treatment plans including HT, 3D-CRT (cp) and 3D-CRT (ncp) were generated and optimized for each patient. All plans were then evaluated with respect to dosimetric parameters exported from dose-volume histogram curves of target and organ-at-risk (OAR). SPSS software was used for statistical analysis. 

The conformity index in the target was similar for all plans (p > 0.05), but HT showed significantly better homogeneity compared to the two 3D-CRT methods (p-value < 0.05). Compared to the 3D-CRT (cp) and 3D-CRT (ncp) plans, the HT plans significantly reduced the mean dose, V13 and V20 values of the kidneys (p-Value < 0.05); V5 values of both kidneys were lower in the 3D-CRT (ncp) plan compared to 3D-CRT (cp) and HT. The difference was statistically significant. Moreover, the results proved that the 3D-CRT (ncp) could better preserve kidneys rather than 3D-CRT (cp). Dmean of the liver for HT plans (20.03) was significantly higher than those for both coplanar and non-coplanar 3D-CRT plans (17.86 and 17.7, respectively).

Generally, HT plans appear to be the best, but in the case of selecting an optimum method, it is necessary to pay attention to the location of tumors compared to OARs.

Y3A5O12:Cr3+ nanophosphor was synthesized by cathodic electrodeposition method. During the preparation procedure, hydroxide precursors were deposited on the surface of cathode via electrochemical reaction and then the final product was achieved by heat treatment of obtained powder at 1100 °C for 4 h. The structure and properties of the obtained product were investigated by various analysis methods such as X-Ray Diffraction (XRD), Fourier Transform InfraRed (FTIR) Spectroscopy, Photoluminescence Spectroscopy (PL), Scanning Electron Microscopy (SEM) and N2 adsorption-desorption analysis. The XRD patterns of the synthesized YAG: Cr product, were in good match with the pure Y3Al5O12 phase and the absence of any other impurities indicates the transformation of Cr3+ ions into the host matrix (YAG). In the emission spectrum of prepared material, a broad emission containing four pronounced bands at 685, 695, 710 and 725 nm was observed that indicates the presence of Cr3+ ions in the final product and further confirmed the formation of desired oxide product (YAG: Cr). The results of our studies showed that cathodic electrodeposition is a practical and highly efficient method for preparation of Y3A5O12:Cr3+ nanophosphor compound.

In this research, we investigated the effect of addition of carbon nanotube (CNT) and sintering processes on mechanical properties of Al- Si3N4 composites. For this purpose difference samples including 5, 10and 15 wt% of Si3N4 with and without 0.25 wt% CNT were fabricated. Samples were sintered via microwave and spark plsma sintering (SPS) methods. Sintering of samples were done at 400°C and 600, 700, 800 °C for spark plasma sinterng process and microwave, respectively. The results showed that the bending strength of samples including 15% Si3N4 with and without CNT that sintered in microwave have maximum value 179 MPa and 212 MPa respectively. Also the bending strength of samples including 15% Si3N4 with and without CNT that sintered in SPS have maximum value 249 MPa and 285 MPa respectively and these samples have higher density than other samples.Also, results showed that the samples that sintered in sps had maximum density and uniformity structure.

The current study aimed to compare the tumor control probability (TCP) and normal tissue complication probability (NTCP) of three-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT) for left-sided breast cancer using radiobiological models.

This study was conducted on 30 patients with left-sided breast cancer, who were planned for 3D-CRT and 6-9 fields IMRT treatments using the PROWESS treatment planning system.  The planning target volume (PTV) dose of 50 Gy was administered for the 3D-CRT and IMRT plans, respectively.  The Niemierko’s equivalent uniform dose (EUD) model was utilized for the estimation of tumor control probability (TCP) and normal tissue complication probability (NTCP). 

According to the results, the mean TCP values for 3D-CRT, 6-fields IMRT, and 9-fields IMRT plans were 99.07 ±0.07, 99.24 ±0.05 and 99.28 ±0.04, respectively, showing no statistically significant difference. The NTCPs of the lung and heart were considerably lower in the IMRT plans, compared to those in the 3D-CRT plans.

From the radiobiological point of view, our results indicated that 3D-CRT produces a lower NTCP for ipsilateral lung. In contrast, for TCP calculations, there was a higher gain with IMRT plans compared to 3D-CRT plans.

Porous NiTi shape memory alloys have shown good potentials for different functional to structural applications as well as biomedical applications. In the present study، highly porous shape memory NiTi alloy specimens were produced via space holder method using urea as a temporary material. The porous NiTi specimens exhibit good pore characteristics and interconnectivity that is appropriate for biomedical applications. Compressive mechanical tests were performed for NiTi specimens with porosity ranged from 42 to 70 percent. It is obvious that the mechanical properties such as Young’s modulu and strength of the porous NiTi decrease with increasing porosity. Apparent Young’s modulus of NiTi specimens decreases from 5. 3 to 3 GPa as porosity increases. Maximum recoverable strain of near to 8. 3% and 7 was achieved for porous NiTi specimens without urea and 50 vol. % urea، respectively. Furthermore، recoverable strain percent is almost constant for superelastic porous NiTi after several cycles.