Search

To assess the efficacy of a transmission‐type parallel plane reference chamber (T‐REF) for small‐field percentage depth dose (PDD) measurements using two high‐resolution detectors. The study utilizes microSilicon and microDiamond detectors for small‐field measurements, both with and without a T‐REF reference chamber. TrueBeam linear accelerator provides various photon energies (6X, 6XFFF, 10X, 10XFFF) for depth dose measurements. A sun‐nuclear 3D water tank is used to measure the PDD up to a depth of 15 cm. Analysis of the data includes a 1D gamma passing rate calculated using an in‐house MATLAB program. The study compares the PDD measurements obtained with and without the T‐REF. The T‐REF exhibits negligible beam perturbations across different field sizes and energies. The overall maximum mean PDD differences are 0.31 ± 0.16% for microSilicon and 0.33 ± 0.17% for microdiamond. The overall mean 1D gamma passing rate is 99.6 ± 0.2%. This study demonstrates that the T‐REF is a reliable and effective reference detector for small‐field radiation dosimetry. [ABSTRACT FROM AUTHOR]

Byline: Arpita. Agarwal, Nikhil. Rastogi, K. Maria Das, S. Yoganathan, D. Udayakumar, Shaleen. Kumar Purpose: With the advent of state-of-the-art treatment technologies, the use of small fields has increased, and [...]

Copyright of Vascular Access is the property of Canadian Vascular Access Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Residents begin their training as an extension of surgeons' hands and end with the assurance they have safe hands. The results of this project will identify needs in the technical skills training of future cardiac surgery residents. We sought to report the capabilities of residents to identify femoral landmarks and the native anterior cruciate ligament (ACL) footprint before and after a structured formal teaching session performed in fall 2018 as a reflection of overall surgical skills training for orthopedic surgery residents in Canada. Among the 188 survey respondents were 77 students, 56 surgeons, 24 residents, 17 nurses and 14 anesthesiologists. Further evaluation of groups that were more positively affected by their UGME anatomy training, such as general surgery and orthopedic surgery residents, may elicit strategies to enhance medical students' interest in surgery. [Extracted from the article]

The paper explores the lead-lag relationship between the variables of order imbalance and return in futures and spot markets. Order imbalance is defined as the difference between buyer and seller initiated trades. Using tick test, the trades have been classified as buyer and seller initiated. The paper finds positive correlation between the variables of order imbalance in the futures market and the returns in the spot market. This relationship is further explored using a VAR framework for daily as well as a shorter interval of 120 min. The results reveal that even after controlling for lagged futures and spot returns, the futures market imbalance has a significant effect on spot market returns. [ABSTRACT FROM AUTHOR]

This study investigates the informational role of options open interests and volume in predicting the future stock prices in Indian market. Most of the time, the uninformed traders lose to informed traders because they neither have private information nor the sophisticated knowledge to process the publicly available information. The most closely watched data are also the least informative. This study is an attempt to find out if the daily published and publicly available options data are informative and can be used to forecast the future stock price at maturity. Then the retail traders and investors will be able to minimize their loss to informed traders and enhance their portfolio performance. The sample of this study is 17 highly traded Nifty 50 index stocks from different sectors having significant share in the index. Predictors based on options price and options volume have been estimated, following Bhuyan and Williams (2004), and then used in the regression model as predictor variables of price at maturity both jointly and in isolation. The period of study covers stock options contract of three months (July-September 2009). Only near month contract is considered for the study because of liquidity concern. The coefficients of predictors are found to be significant and not statistically different across the study period. Consistent with the results of the previous studies, the results show that options open interest and volume are relevant in forecasting future prices. [ABSTRACT FROM AUTHOR]

Purpose/Objective . Small-field measurement poses challenges. Although many high-resolution detectors are commercially available, the EPID for small-field dosimetry remains underexplored. This study aimed to evaluate the performance of EPID for small-field measurements and to derive tailored correction factors for precise small-field dosimetry verification. Material/Methods . Six high-resolution radiation detectors, including W2 and W1 plastic scintillators, Edge-detector, microSilicon, microDiamond and EPID were utilized. The output factors, depth doses and profiles, were measured for various beam energies (6 MV-FF, 6 MV-FFF, 10 MV-FF, and 10 MV-FFF) and field sizes (10 × 10 cm 2 , 5 × 5 cm 2 , 4 × 4 cm 2 , 3 × 3 cm 2 , 2 × 2 cm 2 , 1 × 1 cm 2 , 0.5 × 0.5 cm 2 ) using a Varian Truebeam linear accelerator. During measurements, acrylic plates of appropriate depth were placed on the EPID, while a 3D water tank was used with five-point detectors. EPID measured data were compared with W2 plastic scintillator and measurements from other high-resolution detectors. The analysis included percentage deviations in output factors, differences in percentage for PDD and for the profiles, FWHM, maximum difference in the flat region, penumbra, and 1D gamma were analyzed. The output factor and depth dose ratios were fitted using exponential functions and fractional polynomial fitting in STATA 16.2, with W2 scintillator as reference, and corresponding formulae were obtained. The established correction factors were validated using two Truebeam machines. Results . When comparing EPID and W2-PSD across all field-sizes and energies, the deviation for output factors ranged from 1% to 15%. Depth doses, the percentage difference beyond dmax ranged from 1% to 19%. For profiles, maximum of 4% was observed in the 100%-80% region. The correction factor formulae were validated with two independent EPIDs and closely matched within 3%. Conclusion . EPID can effectively serve as small-field dosimetry verification tool with appropriate correction factors., (Creative Commons Attribution license.)