This work is devoted to studying the influence of chamber response functions on the standard IMRT verification for the different detector technologies available on commercial devices. We have tested three of the most used 2D detector arrays for radiotherapy dosimetry verification, based on air-ionization chambers and diode detectors. The response function has been carefully simulated using the Monte Carlo method and measured through slit and pinhole collimators. Although the response function of air-ionization detectors is considerably different with respect to that of standard diodes, the impact on a verification based in the gamma function with tolerances 3 mm and 3% is quite limited. The results show that the standard air-ionization detector arrays perform in a similar way whenever the tolerances for the gamma function are not lowered below 1.5 mm and 1.5%. Additionally, the sensitivity of these devices to fluence perturbations was measured by intentionally modifying some leaf positions in the multileaf collimator. The wider response function of air-ionization chamber arrays made them slightly more sensitive to random fluence perturbations, although silicon diode arrays are more accurate to describe the dose distribution in a point by point basis.

No abstract

No abstract

In the year 1997 Siemens introduced the virtual wedge in its accelerators. The idea was that a dose profile similar to that of a physical wedge can be obtained by moving one of the accelerator jaws at a constant speed while the dose rate is changing. This work explores the observed behaviour of virtual wedge factors. A model is suggested which takes into account that at any point in time, when the jaw moves, the dose at a point of interest in the phantom is not only due to the direct beam. It also depends on the scattered radiation in the phantom, the head scatter and the behaviour of the monitoring system of the accelerator. Measurements are performed in a Siemens Primus accelerator and compared to the model predictions. It is shown that the model agrees reasonably well with measurements spanning a wide range of conditions. A strong dependence of virtual wedge factors on the dosimetric board has been confirmed and an explanation has been given on how the balance between different contributions is responsible for virtual wedge factors values.

Hoy día con el desarrollo y el avance de la tecnología los productos software son parte de nuestra vida cotidiana. Estos productos constituyen un soporte para casi todas nuestras tareas. Estas tareas pueden tener un desempeño fundamental o no, y van desde ejecutar la conducción de un avión a través de un piloto automático hasta posibilitar el funcionamiento de los dispensadores de billetes o cajeros automáticos. Por la criticidad de los procesos en los que ellos se encuentran relacionado, es necesario que se cumplan dos características fundamentales; la primera, que tengan un nivel de calidad aceptado y la segunda, que sean productos seguros.La seguridad en los softwares es un atributo no funcional que influye directamente en la calidad del producto. Realizar pruebas a los requisitos no funcionales  para constatar su desempeño, tal y como se hace con los requisitos funcionales es una tarea tediosa. Como alternativa a este problema se han desarrollado herramientas que de forma automática o semiautomática realizan pruebas de diferente índole a los sistemas. El objetivo de este trabajo es identificar las herramientas software existentes para realizar pruebas relacionadas con la seguridad. Para cumplir este objetivo se realiza un estudio del estado del arte de las herramientas para realizar pruebas de seguridad desde el 2010 a la fecha.