3 Dimensional Conformal Radiotherapy (3D-CRT) planning software helps in displaying the 3D dose distribution at different levels in the planned target volume (PTV). Physical or dynamic wedges are commonly applied to obtain homogeneous dose distribution in the PTV. Despite all these planning efforts, there are about 10% increased dose hot spots encountered in final plans. To overcome the effect of formation of hot spots, a manual forward planning method has been used. In this method, two more beams with multi-leaf collimator (MLC) of different weights are added in addition to medial and lateral wedged tangent beams. Fifteen patient treatment plans were taken up to check and compare the validity of using additional MLC fields to achieve better homogeneity in dose distributions. The resultant dose distributions with and without presence of MLC were compared objectively. The dose volume histogram (DVH) of each plan for the PTV was evaluated. The 3D dose distributions and homogeneity index (HI) values were compared. The 3D dose maximum values were reduced by 4% to 7%, and hot spots assumed point size. Optimizations of 3D-CRT plans with MLC fields improved the homogeneity and conformability of dose distribution in the PTV. This paper outlines a method of obtaining optimal 3D dose distribution within the PTV in the 3D-CRT planning of breast cases.

Photosynthetic rates, chlorophyll content and activity of ribulose 1,5-diphosphate carboxylase (RuDPC) were determined for 18 genotypes of wheat (Triticum aeslivum L.) in pot culture. Measurements were made at various growth stages. Correlation studies between physiological characteristics and seed yield were made at each stage separately.Genotypic variations were observed at different growth and developmental stages in photosynthetic rates (1-8-2-7-fold), chlorophyll contents (1-2-fold) and enzyme activities (2-fold). Chlorophyll content and enzymic activity increased in plant leaves with advancing age while apparent rates of photosynthesis decreased.RuDPC activity in flag leaf at anthesis showed significant positive correlation with grain yield (r = 0-55). Other attributes did not show significant association with grain yield.

Aim:The purpose of this study is to verify the accuracy of the commissioning of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) based on the recommendation of the American Association of Physicists in Medicine Task Group 119 (TG-119).Materials and Methods:TG-119 proposes a set of clinical test cases to verify the accuracy of IMRT planning and delivery system. For these test cases, we generated two sets of treatment plans, the first plan using 7–9 IMRT fields and a second plan utilizing two-arc VMAT technique for both 6 MV and 15 MV photon beams. The template plans of TG-119 were optimized and calculated by Varian Eclipse Treatment Planning System (version 13.5). Dose prescription and planning objectives were set according to the TG-119 goals. The point dose (mean dose to the contoured chamber volume) at the specified positions/locations was measured using compact (CC-13) ion chamber. The composite planar dose was measured with IMatriXX Evaluation 2D array with OmniPro IMRT Software (version 1.7b). The per-field relative gamma was measured using electronic portal imaging device in a way similar to the routine pretreatment patient-specific quality assurance.Results:Our planning results are compared with the TG-119 data. Point dose and fluence comparison data where within the acceptable confident limit.Conclusion:From the obtained data in this study, we conclude that the commissioning of IMRT and VMAT delivery were found within the limits of TG-119.

The ZnO and Mo:ZnO thin films were deposited by radio frequency magnetron sputtering on quartz and intrinsic silicon (100) substrates at a fixed combined partial pressure 1×10 −2 mbar of Ar + O 2 and substrate temperatures of 473 K and 673 K. The effect of Molybdenum doping on ZnO thin films with different Molybdenum concentrations (1-2 atomic percent) was studied with the help of structural and microstructural characterization techniques. The films deposited at a substrate temperature of 473 K exhibited strong -axis orientation with predominant (002) peak. At 673 K, along with (002) orientation, other orientations (100), (101), (220), and (103) were also observed. Among these, the (220) peak indicates the cubic phase of ZnO. With increasing Molybdenum concentration, the cubic phase of ZnO disappeared, and the (002) orientation became strong and intense. The composition analysis reveals that the undoped ZnO films deposited at 473 K have oxygen deficiency, and the ratio of Zn/O is improved with increasing Mo atomic percent in ZnO. The surface morphological features reveal that the undoped ZnO films were found to be uniform and have grain size of around 30 nm. The optical energy gap of the undoped ZnO films is 3.05 eV and increases with increasing Mo concentration. The thickness of the films is around 456 nm.

The aim of this study was to examine the impact of dose rate on accuracy of intensity modulated radiation therapy (IMRT) plan delivery by comparing the gamma agreement between the calculated and measured portal doses by pretreatment quality assurance (QA) using electronic portal imaging device dosimetry and creating a workflow for the pretreatment IMRT QA at hospital levels. As the improvement in gamma agreement leads to increase in the quality of IMRT treatment delivery, gamma evaluation was carried out for the calculated and the measured portal images for the criteria of 3% dose difference and 3 mm distance-to-agreement (DTA). Three gamma parameters: Maximum gamma, average gamma, and percentage of the field area with a gamma value>1.0 were analyzed. Three gamma index parameters were evaluated for 40 IMRT plans (315 IMRT fields) which were calculated for 400 monitor units (MU)/min dose rate and maximum multileaf collimator (MLC) speed of 2.5 cm/s. Gamma parameters for all 315 fields are within acceptable limits set at our center. Further, to improve the gamma results, we set an action level for this study using the mean and standard deviation (SD) values from the 315 fields studied. Forty out of 315 IMRT fields showed low gamma agreement (gamma parameters>2 SD as per action level of the study). The parameters were recalculated and reanalyzed for the dose rates of 300, 400 and 500 MU/min. Lowering the dose rate helped in getting an enhanced gamma agreement between the calculated and measured portal doses of complicated fields. This may be attributed to the less complex motion of MLC over time and the MU of the field/segment. An IMRT QA work flow was prepared which will help in improving the quality of IMRT delivery.