HERCA proposal on harmonization of DAP units

On the occasion of the 10th meeting of the Board of Heads of HERCA (Paris, 30-31 October 2012), a proposal for harmonization of DAP units in general and in interventional radiology has been approved.

The enhancement of the implementation of the radiation protection regulation on medical applications, focusing on justification and optimization, is part of the missions of HERCA.

In interventional radiology and general radiography, it is essential that the Dose Area Product (DAP) values are displayed and the associated units are readily understood by the user who may be working with many other X-ray equipments from various manufacturers in different places.

Thus to avoid misinterpretation of the DAP information displayed on different X-ray equipments and hence, to avoid the risk of error in the trasmission of information, the issue of the need for harmonisation of DAP units has been raised.

For ease of interpretation of dosimetric data, HERCA proposes that the DAP unit is:

  • the same for the same domain of use, i.e. general radiography on one hand and interventional radiology on the other hand;
  • suited to the range of doses delivered depending on domain, including paediatrics procedures.

The HERCA WG MA proposes to use as DAP unit:

Gy×cm² for interventional radiology and mGyxcm2 for general radiography.

HERCA believes that the use of harmonized DAP units can highly contribute to the objective of reducing patient dose. Consequently, two respective letters have been sent to COCIR and IEC inviting them to take this proposal into account in its future works.


HERCA-DAP display proposal 2012 31 10


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