Diagnostic Reference Levels Dervied from Recent Surveys on Patient Dose for Various Types of Radiological Examination in the Netherlands

In recent years surveys have been performed in the Netherlands to determine patient doses for various types of examination in diagnostic radiology. These surveys comprised examinations of chest, breast, colon, computed tomography and non-cardiovascular radiology procedures. In general, in these studies measurements were performed at 10 to 20 X ray units in different hospitals. The majority of the studies aimed at determination of effective dose as this quantity is generally assumed to he most directly related to the risks to patients due to exposure to ionising radiation. The information content of radiological images must be adequate to provide a correct medical diagnosis or guide treatment. Therefore, some of the studies also included assessment of image quality Preliminary reference levels are proposed for the various types of examination as performed in the Netherlands in terms of effective dose and, where possible, also in terms of readily measurable quantities such as entrance surface air kerma, entrance surface dose or dose area product.