Determination of diagnostic x-ray beam quality

Half-value layer (HVL) checks at certain KVp settings were carried out on diagnostic x-ray machines in the Radiology Department of the University of Ilorin Teaching Hospital. A simple penetrameter technique which is based on the transmission of a hardened x-ray beam through an aluminium step wedge and reference discs simultaneously was used. The different degrees of beam attenuation were displayed on a radiographic film while a densitometer was used to measure the corresponding optical density values. Results were obtained from a calibration plot of HVL versus optical density. A comparison of results with literature values for same settings of KVp and filtration showed a very good agreement. The technique which is simple and reliable, is recommended for use in some developing countries where economic constraints would not permit the importation of essential test tools for radiodiagnostic quality assurance measurements.