Evaluation of X-ray fields characteristics using a Farmer chamber

The aim of this work was to use a Farmer-type ionization chamber to evaluate some characteristics of the X radiation fields of the mobile equipment from the Medical Physics laboratory of UFCSPA. The motivation of this verification is due to its importance for the proper use of this equipment during the practical classes and for research. Farmer chamber stability tests were performed to ensure the reliability of the measured values, as recommended by the International Electrotechnical Commission. The stability tests showed that the ionization chamber response is stable and within the recommended limits. The characteristics of the radiation field evaluated were: field uniformity, half-value layer (HVL) and homogeneity coefficient. The results of field uniformity, for the most part, were higher than the 5% variation established by ISO 4037-1. Nevertheless, the HVLs have met the values recommended by RDC Nº 330 and the homogeneity coefficients are in accordance with the typical values for Radiodiagnostic determined by the IAEA International Code of Practice on Radiology. (author)