[en] Quality control is the result of planning, process development, training, monitoring of equipment performance, documentation of results and evaluation of uncertainties. The graphical presentation of data can provide useful information about variations and trends. In radiotherapy, the dose delivery process is monitored daily through the output factor. Often documenting this factor in a trend graph does not rely on reliable quantitative information to act on behavioral tendency alone. Statistical Process Control (SPC) is a quality tool that presents a method of detecting problems, distinguishing between common or special causes in the evaluated process. This paper describes quality assurance from a process behavior point of view using the SPC method. From the control chart it was possible to evaluate the behavior of the variation of the output factor of the linear accelerator and make the decision to calibrate the beam based on this graph. The control limits were established, before and after the calibration of the beam. The dose delivery process was recognized as over control by analyzing the control graph according to the evaluation rules. The general objective of this work is to describe the implementation of the SPC as a method of evaluating the delivery of the dose, through the output factor, which provides a reliable quantitative justification to act based on the control chart. (author)

[en] The reference condition established to determine the absorbed dose in water of a linear accelerator, according to TRS-398, depends on some electro-mechanics parameters. Furthermore, in principle, uncertainties in the parameters settings may results in dosimetry variations. The goal of this study is to analyze the influence in quality control parameters changes, which tolerance limits are established by TECDOC-1151, in the dosimetry result of photon beam. For this, some parameters (gantry and collimator angle, field size and source to surface distance) and chamber position were changed. The results of these changes were evaluated. For the variation range of quality control items (that went beyond the tolerance limits established by TECDOC-1151), the deviations got less than 1 % of reference for all analyzed parameters; the deviations for the ionization chamber position variation were less than 0,2 % for lateral and longitudinal variations although almost got to 3 % for depth alterations. (author)

[en] The reference condition established to determine the absorbed dose in water of a linear accelerator, according to Tars-398, depends on some electro-mechanics parameters. Furthermore, in principle, uncertainties in the parameters settings may results in dosimetry variations. The goal of this study is to analyze the influence in quality control parameters changes, which tolerance limits are established by TECDOC-1151, in the dosimetry result of photon beam. For this, some parameters (gantry and collimator angle, field size and source to surface distance) and chamber position were changed. The results of these changes were evaluated. For the variation range of quality control items (that went beyond the tolerance limits established by TECDOC-1151), the deviations got less than 1 % of reference for all analyzed parameters; the deviations for the ionization chamber position variation were less than 0,2 % for lateral and longitudinal variations although almost got to 3% for depth alterations. (author)

[en] This report shows the development of a project done by ABFM (Brazilian Association of Medical Physics) to assist in a request from CNEN (National Nuclear Energy Commission) regarding the external audit process. This document shows how the request for this demand occurred, formation of the study group, development of the adopted methodology, in addition to the results defined by the group and the recommendations presented to CNEN. The group followed the document from the International Atomic Energy Agency as a reference and eleven meetings were held for discussion. The recommendations were divided into items to facilitate verification: linear accelerator, brachytherapy, planning system, management system and processes. (author)