Procedimiento para el uso de la radiografía computarizada en el control dosimétrico de la calidad de las unidades de cobaltoterapia

Abstract

Within the quality control of the teletherapy equipment of Cobalt 60, its dosimetric characterization is of great importance. One of the ways to execute this procedure is using digital images. The objective of this work is to develop a procedure that includes mathematical processing for the effective use of computerized radiography in the dosimetric quality control of cobalt units 60 that ensures the quality of patient treatments. For its design, the uniformity of the response and the useful exposure level of this image system were studied. The appropriate image filter was selected and the mathematical model was calculated for the conversion of pixel values into relative dose values. An application for image processing and control was implemented in Matlab. For the evaluation of the procedure, a precision study was carried out in obtaining the quality control parameters and the profiles obtained by the proposed procedure and those obtained by an array of detectors were compared. As a result, differences of less than 1% were obtained in the region of the profile where the measurements of the control parameters are made. The application of the proposed procedure allows the technical evaluation of the units of cobalt 60 without this leading to the exit of its therapeutic use, which makes possible a better planning of the preventive maintenance. In a general way it favors the organization of work and represents an improvement in the assurance of the quality of the treatments to the patients.