Optimisation of patient radiation protection in conventional X-ray imaging procedures using film reject analysis: a demonstration of the importance of rare earth screen-film systems.

The optimisation of patient protection was studied using a conventional film screen of speed class 200 and a rare earth film screen of speed class 400. The entrance surface dose (ESD) for the two film-screen systems was determined for patients undergoing some common diagnostic procedures (chest, lumbar spine and pelvis series). The ESD was the optimising parameter and its trade off with the image quality assessment of the radiographs. The estimated ESDs were compared with reference levels set by the Commission of the European Communities for a typical standard adult patient. A mean dose reduction of 17-33 % was achieved upon adoption of a rare earth film screen of speed class 400. Regular assessment of patient dose, quality control (QC) of parameters that affect the patient dose and image quality, adoption of faster rare earth screens and optimum radiographic technique are recommended in order to achieve optimisation goals.