Intensity‐modulated radiation therapy (IMRT) is a complex procedure that involves the delivery of complex intensity patterns from various gantry angles. Due to the complexity of the treatment plans, the standard care is to perform measurement‐based, patient‐specific quality assurance (QA). IMRT QA is traditionally done with film for relative dose in a plane and with an ion chamber for absolute dose. This is a laborious and time‐consuming process. In this work, we characterized, commissioned, and evaluated the QA capabilities of a novel commercial IMRT device, Delta4, (ScandiDos, Uppsala, Sweden). This device consists of diode matrices in two orthogonal planes inserted in a cylindrical acrylic phantom that is 22 cm in diameter. Although the system has detectors in only two planes, it provides a novel interpolation algorithm that is capable of estimating doses at points where no detectors are present. Each diode is sampled per beam pulse so that the dose distribution can be evaluated on segment‐by‐segment, beam‐by‐beam, or as a composite plan from a single set of measurements. The end user can calibrate the system to perform absolute dosimetry, eliminating the need for additional ion chamber measurements. The patient's IMRT plan is imported into the device over the hospital LAN and the results of the measurements can be displayed as gamma profiles, distance‐to‐agreement maps, dose difference maps, or the measured dose distribution can be superimposed on the patient's anatomy to display an as‐delivered plan. We evaluated the system's reproducibility, stability, pulse‐rate dependence, dose‐rate dependence, angular dependence, linearity of dose response, and energy response using carefully planned measurements. We also validated the system's interpolation algorithm by measuring a complex dose distribution from an IMRT treatment. Several simple and complex isodose distributions planned using a treatment planning system were delivered to the QA device; the planned and measured dose distributions were then compared and analyzed. In addition, the dose distributions measured by conventional IMRT QA, which uses an ion chamber and film, were compared. We found that the Delta4 device is accurate and reproducible and that its interpolation algorithm is valid. In addition, the supplied software and network interface allow a streamlined IMRT QA process.PACS number: 87.56Fc
Purpose: Characterize, commission and evaluate a dual plane diode matrix IMRT QA device. Method and Materials: A novel device consisting of diode matrices in two orthogonal planes inserted in a cylindrical acrylic phantom of 22cm diameter is characterized, commissioned and evaluated for radiotherapy quality assurance. The system interfaces readily with a networked computer making the whole IMRT QA process very efficient in multi accelerator and multi physicist department. It detects charge per accelerator pulse, computes and displays measured dose distribution in 3D space. The temperature dependence of the diode is corrected. The precision, stability, pulse rate dependence, dose rate dependence, angular dependence, linear response, energy response of the system and the calculation accuracy at non detector locations are evaluated in addition to comparing multiple simple and complex iso‐dose distributions from TPS to measured distributions. The software readily analyses dose profiles in any orientations, %dose, DTA and gamma index of the entire 3D distributions. Results: The precision and the day‐to‐day reproducibility of measured data of a single field are excellent, making additional ion chamber measurement unnecessary. The measured data indicated excellent dose linearity and pulse rate independence. Comparison of simple and complex treatment plans with delivered treatment showed good agreement considering the error bars. Conclusions: The Delta 4 system is highly efficient, accurate and reproducible. The instantaneous and automatic data acquisition combined with the error analysis, report and database capability built into the system make it easy, convenient and efficient to use in a busy clinic. Conflict of Interest Statement: One of the co‐author is President and CEO of ScandiDos AB Company, which supplied Delta4 at no cost for evaluation.
LAGO is an extended cosmic ray observatory composed of water-Cherenkov detectors (WCD) placed throughout Latin America. It is dedicated to the study of various issues related to astrophysics, space weather and atmospheric physics at the regional scale. In this paper we present the design and implementation of the front-end electronics and the data acquisition system for readout of the WCDs of LAGO. The system consists of preamplifiers and a digital board sending data to a computer via an USB interface. The analog signals are acquired from three independent channels at a maximum rate of $ 1.2 Â 10 5 pulses per second and a sampling rate of 40 MHz. To avoid false trigger due to baseline fluctuations, we present in this work a baseline correction algorithm that makes it possible to use WCDs to study variations of the environmental radiation. A data logging software has been designed to format the received data. It also enables an easy access to the data for an off-line analysis, together with the operational conditions and environmental information. The system is currently used at different sites of LAGO.
En el artículo se abordó uno de los problemas más importantes y actuales para el proceso de enseñanza-aprendizaje del inglés como lengua extranjera: la formación y desarrollo de la competencia comunicativa oral profesional pedagógica. Para ello, los autores realizaron una sistematización de los elementos esenciales que han dado tratamiento al tema. Investigación descriptiva, desde una posición crítica y dialéctica permite revelar faltantes a resolver por vía científica que dieron lugar a los resultados de un proyecto de investigación orientado a la didáctica específica del Inglés como segunda lengua. Para la fase de diagnóstico-fáctico: observación científica, se encuestaron a 70 estudiantes seleccionados desde un muestreo aleatorio estratificado de la carrera de Licenciatura en Educación, especialidad Lengua Inglesa, que representa un 35,2% de la población. Una segunda encuesta, se aplicó a 10 profesores de Práctica Integral de la Lengua Ingles y se entrevistaron 20 docentes con experiencia en la Educación Superior Pedagógica El objetivo fundamental radica en el análisis de fundamentos teóricometodológicos sobre las principales categorías pedagógicas de la competencia comunicativa oral profesional pedagógica en inglés, con un enfoque sistémico-comunicativo. Todo lo anterior conforma la novedad de una investigación terminada en la
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