STATE OF THE ART
There are some broad guidelines for routine, special and task-related individual monitoring recommended by ICRP in Publication 54 [ICRP 1988] and Publication 78 [ICRP 1998]. These guidelines have the following general features:
Routine monitoring is carried out at regular time intervals during normal operations, and for the interpretation of routine monitoring data it is assumed that an acute intake occurs at the mid-point of the monitoring interval.
In special and task-related monitoring it is assumed that an acute intake has occurred at the corresponding time.
The reconstruction of an intake is usually performed on a basis of a single data point in a time series of measurements. If more than 10% of the actual measured quantity can be attributed to intakes in previous monitoring intervals, making a corresponding correction is recommended.
In case of inhalation, all types of interpretation schemes require a priori information about the Lung Absorption Type and the aerosol particle size. If no information about the particle size is available, it is recommended to assume the default value for the activity median aerodynamic diameter (AMAD) of 5 mm [ICRP 1998].
These guidelines leave most of the assumptions open, this resulting in many different approaches for the interpretation of monitoring data as demonstrated by the 3rd European Intercomparison Exercise on Internal Dose Assessment [Doerfel et al. 2000]. Recently, there has been some progress in developing guides for the application of the models, the most important of which being the "Guide for the Practical Application of the ICRP Human Respiratory Tract Model" [ICRP 2001]. These guides, however, refer only to special issues of internal dosimetry. Consequently, there is a need for general guidelines covering consistently all relevant issues for the interpretation of monitoring data.