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Introduction: Radiation dose measurement plays a major role in Radiation Dosimetry. Effective dose delivery to the patient is ensured with the recommendation of some protocol called Quality assurance (QA). It is necessary to confirm that the beam that is used for treatment is a good quality beam and it is given by beam quality factor TPR 20/10 which is one of the QA protocols. Material and Methods: In the present TPR20,10 phantom both depth (20 and 10 cm) doses can be measured at the same procedure without changing any setup. As the reference condition is maintained, the Gelatin-based phantom is kept for irradiation in the Siemens Linear Accelerator (LINAC) machine. Initially Source Axis Distance (SAD) of 100 cm from the surface and 10×10 cm2 of field size. The measurement is taken by ion chamber at 10 and 20 cm depth in gantry angles 90° and 270° And the ratio of these values is taken and compared with the measurements of the water-based TPR phantom. Results: The values for the TPR20,10 ratio for the Gelatin and water phantom are measured using the above method and the values are tabulated and compared. Likewise, the output measurements are done and tabulated for comparison. These measurements are carried out for several days to check the repeatability, and reproducibility of the phantom. Also, the measured set of values was analyzed using mean, median, standard deviation, etc. Conclusion: The fabricated phantom had good outcomes in its response. And the result projects that the phantom can be a better alternative for the other phantom materials and gelatin has more advantages over water, we conclude that gel can be used for better dosimetric procedures.

The Treatment Planning System (TPS) in radiotherapy often faces challenges in optimizing techniques for large tumor volumes due to mechanical limitations, such as the over-travel distance of the Multileaf Collimator (MLC). This study compares the dosimetric outcomes of split field and open field techniques in Volumetric Modulated Arc Therapy (VMAT) for carcinoma tongue patients with large target volumes. Twenty-one patients treated with VMAT were evaluated using Eclipse™ TPS. The dosimetric parameters including conformity index, homogeneity index, and dose to Organs at Risk (OAR) were compared between split and open field techniques. Methods: VMAT plans utilizing two arcs were generated in Eclipse™ TPS with 6MV photon beams on a Truebeam STx Linear accelerator for all patients using both split and open field techniques. In the split field technique, fields were split along the X-Jaw direction. Optimization objectives and collimator angles were kept consistent for both techniques. Dosimetric data were collected and analyzed for conformity index, homogeneity index, and OAR doses. Results: The study revealed a 3% and 4% difference in homogeneity index, with conformity index values averaging 95% and 97% for split and open fields, respectively. Split field technique demonstrated reduced doses to OARs including Brainstem Dmax (9%), Spinal cord Dmax (6%), PORV cord Dmax (5%), Right Parotid Mean Dose (3%), Left Parotid Mean Dose (3%), Right Parotid (D50%) (5%), and Left Parotid (D50%) (2%), compared to the open field technique. The 50% isodose volume was also 4% lower in the split field technique. While the maximum dose remained identical, differences were observed in homogeneity index, conformity index, maximum dose, and mean dose to OARs. Conclusion: The split field technique demonstrates superior dosimetry outcomes with reduced doses to OARs compared to the open field technique, albeit with increased treatment time. Thus, the split field technique presents as a favorable option for planning large target volumes in carcinoma tongue cases. [ABSTRACT FROM AUTHOR]

Purpose: To investigate ion recombination (Ks) and polarity correction factor (Kpol) for small and large field sizes using small volume ionization chamber for Flattening Filter (FF) and flattening Filter Free (FFF) beams of Varian TrueBeam STx linear accelerator. Materials and Methods: All the readings were measured on PTW BEAMSCAN® water phantom at 100cm source to surface distance (SSD) at dmax and 10cm depth for 6, 10, 15, 6FFF and 10FFF mega voltage photon beams with maximum dose rate for square fields from 0.5×0.5cm² to 30×30cm². Two ion chambers such as PTW Semiflex 3D 31021 and Farmer chamber 30013 of volumes 0.07cc and 0.6cc respectively were hired. The correction factors were computed from the readings according to the protocol no 398 of International Atomic Energy Agency's Technical Report Series (IAEA TRS 398). The Ion recombination values obtained from "Two-Voltage Method" (TVM) were verified with 1/V versus 1/Q curves (Jaffé-plots) for all the beam energies. Results: From the result, the Ion recombination correction factors (Ks) never exceeded 1.032, additionally the Jaffé-plot's results agree very well with TVM values (varies up to 0.3%), except for square fields 0.5×0.5cm² and 1×1cm² (up to 8%). The Ks values are completely independent of field sizes for all beam energies. The Kpol values varies independently with field sizes up to a square field 2×2cm², between square fields 2×2cm² to 10×10cm² the plot shows almost a straight line for all radiation condition. For all the square fields (except 0.5×0.5cm² and 1×1cm²), Ks and Kpol values of FFF beams only varies by a maximum of 0.6% and 0.1% from the values of FF beams respectively. Conclusion: The saturation voltage of the small field dosimeters is greater than the dosimeter working voltage. The Ks and Kpol values of small fields are different from standard field (reference field). The ion recombination can be adequately accounted for high dose rate FFF beams using Ks determined with the standard "Two-Voltage Method". The result obtained from FFF beams doesn't deviate significantly from flattened beams. The inappropriate readings of square fields 0.5×0.5cm² and 1.0×1.0cm² may be, also due to the lack of dosimeter response as a result of lack of lateral charged particle equilibrium and volume averaging effect of the chamber. [ABSTRACT FROM AUTHOR]

Antibody phage display technology was used to immortalize genes from a hybridoma clone encoding monoclonal antibody against staphylococcal enterotoxin B (SEB) which is the most potent toxin listed as biological warfare (BW) agent. The results demonstrated the application of the constructed recombinant antibody via immortalizing the antibody genes from a hybridoma clone for immunodetection of SEB.

Loading conditions and complex geometry have led the cylinder head to become the most challenging part of diesel engines. A high power diesel engine cylinder head analysed by means of both fluid-dynamic and thermo-structural simulations. First, the computational fluid dynamics (CFD) analysis was done on whole cylinder head i.e. covering both the cooling jacket and metal cast. A 3-D geometric model of a cylinder head with water jacket was designed by using Creo Parametric 2.0 software. Then the mesh was imposed on the model using the ANSYS Fluent software. Input conditions and thermal boundaries were defined and the standard k−ε model is utilized to carry out simulations with the CFD Fluent software. The pressure distribution and velocity field distribution of the cylinder head’s water jacket were analysed. In addition, the thermal boundary conditions of the cylinder head which were obtained from CFD analysis has applied as a boundary condition to structural analysis. As it was a coupled field analysis, this gives more accurate results in both CFD as well as in Thermo-Mechanical analysis. Stress and deformation which are obtained from the thermo-mechanical analysis were within the safe limit. [ABSTRACT FROM AUTHOR]