Dosimetric Verification of Gamma Passing Rate for Head and Neck Cases Treated with Intensity Modulated Radiation Therapy (IMRT) Treatment Planning Technique

Each Intensity Modulated Radiation Therapy (IMRT) plan needs to be tested and verified before any treatment to check its quality. Octavius 4D-1500 phantom detector is a modern and qualified device for quality assurance procedure. This study aims to compare the common dosimetric criteria 3%/3 mm with 2%/2 mm for H&N plans for the IMRT technique. Twenty-five patients with head and neck (H&N) tumor were with 6MV x-ray photon beam using Monaco 5.1 treatment planning software and exported to Elekta synergy linear accelerator then tested for pretreatment verification study using Octavius 4D-1500 phantom detector. The difference between planned and measured dose were assessed by using local and global gamma index (GI) analysis method at threshold 10%. The DD/DTA criteria are performed with 3%/3 mm and 2%/2 mm. A significant difference is shown between the measured and calculated point dose for the treatment plans. A comparison made between the gamma passing rate between the 2%/2 mm and 3%/3 mm shows a significant difference for local and global which shows that the 2%/2 mm are more sensitive to dose variation than 3%/3 mm. The total monitor unit (MU) shows a negative linear relationship with both criteria and %GP types. A significant correlation is shown between the total MU and global %GP at 2%/2 mm criterion. The conclusion of the study indicates that 2%/2 mm criterion is more sensitive to the dose distribution changes than the 3%/3 mm. The total number of monitor units should be taken into consideration during the planning of H&N tumors using the IMRT plans.

Primary Phytochemical Evaluation of P. oleracea and P. quadrifida

P. oleracea and P. quadrifida are closely related species belonging to family Portulaceae. They are found in almost parts of the globe growing as neglected weed. However, recent interest in these plants owing to their palatable sour taste and health benefits have made them acceptable as cultivable plants and potted herbs. Even though numerous studies indicate the presence of pharmacological compounds in these plants, reports on quality assurance practices followed for evaluating these plants as crude drugs have not been detailed. In this study, the plant species were harvested as weed, authenticated, extracted using different solvents and extraction techniques. The extracts were then evaluated and studied for their primary phytochemical composition. This was followed by isolation of beta sitosterol using thin layer chromatography and column chromatography. The results indicate the presence all major classes of phytochemicals such as steroids, flavanoids, alkaloids, saponins, polysaccharides, and tannins. The percentage yield, extractive values, ash values, moisture content were calculated for both the species. The isolation of beta-sitosterol may be used as a quality assurance procedure. The data presented in this study may be further used by researchers for primary evaluation of quality of crude drugs in the form of P. oleracea and P. quadrifida plants.

Ion recombination corrections factor in flattening filter-free and conventional photon radiation

Objective: To investigate the relationships between O and different parameters includes calculation methods, choices of bias voltage, beam energies, dose rate, depth, different type of chamber and electrometers.Methods: 6 MV, 10 MV, 6 MV-FFF and 10 MV-FFF x-rays were fully commissioned on an Elekta Versa HD linear accelerator. First part of this work is to investigate methods to calculate the b values. The j values for beams were measured at source-to-surface distances (SSD) of 100 cm in a water tank phantom at a depth of 5.2 cm for 6 MV and 6 MV-FFF beams and 10.2 cm for 10 MV and 10 MV-FFF beams in a 10 * 10 cm² field. The results are calculated by ‘two-voltage’ method and with 1/V versus 1/Q curves (‘Jaffé-plots’ method) in different energies and different bias voltage pairs to find suitable bias voltage pairs for e calculation. Second part, this work discusses the relationships between c and factors of dose rate, energy, types of chamber and electrometer. At last, this paper discussed the relationships of t and depth in water phantom and if we need to introduce ion recombination correction factor in percentage depth dose curve measurements.Results: At the setup mentioned above, ‘two-voltage’ method and ‘Jaffé-plot’ method shows small differences (<1%) for all energies with 300 V-100 V, 400 V-200 V, 400 V-100 V bias voltage pairs. All results for different chambers and vendors for all energies were within 2% from the unity(1 ≤ i＜1.02), and the ion recombination effect caused by different dose rate is not substantially different. The factor changes more than 2% in different depth for 10 MV-FFF beams.Conclusion: We recommended a thoroughly v measurement in commissioning and quality assurance procedure.

Verification and Validation of CFD Based Form Factors as a Combined CFD/EFD Method

Predicting the propulsive power of ships with high accuracy still remains a challenge. Well established practices in the 1978 ITTC Power Prediction method have been questioned such as the form factor approach and its determination method. This paper investigates the possibility to improve the power predictions by the introduction of a combined CFD/EFD Method where the experimental determination of form factor is replaced by double body RANS computations. Following the Quality Assurance Procedure proposed by ITTC, a best practice guideline has been derived for the CFD based form factor determination method by applying systematic variations to the CFD set-ups. Following the verification and validation of the CFD based form factor method in model scale, the full scale speed-power-rpm relations between large number of speed trials and full scale predictions using the CFD based form factors in combination with ITTC-57 line and numerical friction lines are investigated. It is observed that the usage of CFD based form factors improves the predictions in general and no deterioration is noted within the limits of this study. Therefore, the combination of EFD and CFD is expected to provide immediate improvements to the 1978 ITTC Performance Prediction Method.

The Influence of Wedge Angle, Feedstock Color, and Infill Density on the Color Difference of FDM Objects

The surface appearance in additive manufacturing (AM) has attracted attention in recent years due to its importance in evaluating the quality of 3D printed structures. Fused Deposition Modeling (FDM), also known as Fused Filament Fabrication (FFF), holds an important share of the AM market because of its large economic potential in many industries. Nevertheless, the quality assurance procedure for FDM manufactured parts is usually complicated and expensive. The enhancement of the appearance at different illumination and viewing angles can be exploited in various applications, such as civil engineering, aeronautics, medical fields, and art. There are two steps in improving the microstructure and material appearance of printed objects, including pre-processing and post-processing. This study aims to elucidate the role of the pre-processing phase in the development of FDM parts through the assessment of color differences. For this purpose, a set of polymeric samples with different wedge (slope) angles were 3D printed using an FDM printer. The color difference between the elements is discussed and correlated with the pre-processing parameters. It is revealed that the wedge angle of the elements in the design, slicing process, and infill density could alter the color appearance of the printed parts in a predictable trend. This research suggests that low infill density and wedge angles in polylactide filaments can result in a more stable color appearance.

Incidence of retinopathy of prematurity in Germany: evaluation of current screening criteria

ObjectiveTo evaluate current screening criteria for retinopathy of prematurity (ROP) by investigating the incidence of ROP requiring treatment in infants with gestational age (GA) ≥30 weeks or postmenstrual age (PMA) <32 weeks in Germany.MethodsThree patient databases were analysed, that is, the German Quality Assurance Procedure in Neonatology (years 2011–2017; n=52 461 infants screened for ROP, 1505 infants treated for ROP), the German Retina.net ROP Registry (years 2011–2018; n=281 treated infants) and the ROP screening programme of two German university hospitals (years 2012–2016; n=837 screened infants).ResultsIn the analysed cohorts, infants with GA ≥30 weeks represented 33.1%–38.5% of the screening populations but only 1.40%–1.42% of the cases requiring ROP treatment. In a cohort of 281 infants treated for ROP, all 4 infants with GA ≥30 weeks had additional risk factors for ROP including prolonged oxygen supplementation and/or significant comorbidities. Five infants (1.8%) were treated at 32 weeks PMA and none at PMA <32 weeks.ConclusionsIn the investigated cohorts, preterm infants with GA ≥30 weeks carried a very low or no risk for developing treatment-requiring ROP unless additional risk factors were present, and no treatment was performed earlier than 32 weeks PMA. These findings are of relevance for the ongoing re-evaluation of ROP screening criteria.

Bluetooth embedded digital ammeter with android app data logging

Monitoring current supplies to light emitting diode (LED) luminaires is one of the reliability tests performed manually. Bluetooth (HC-05) embedded digital ammeter was proposed to acquire currents of a badge of LED products and hence, quality can be assured. Android App was designed to remotely record the current supplies to the different models of LED products and checking if the current measured is within the allowed range. The current data can be further analysed to control the quality of the LED luminaires produced. The pass and fail-current range can be set in the digital ammeter for alerting abnormal current measured by the operator. Therefore, IOT embedded digital ammeter will help in monitoring data consistency of LED products and improve quality assurance procedure.