Dose area product
The dose area product , abbreviated DFP, is a measured variable in dosimetry and the basis for calculating the radiation exposure during an X-ray exposure with an X-ray device (e.g. fluoroscopy, angiography, grid wall device, mobile C-arm, etc.). The dose area product is sometimes also called area dose product , abbreviated to FDP.
Since both the exposed area and the dose are included in the calculation of the dose area product, the value of this quantity is independent of the distance to the radiator. The DFP is measured with ionization chambers that are attached to the radiation exit window of the X-ray machine. They document the radiation dose to which the patient was exposed during the examination. The DFP is of great importance for the risk assessment of radiation exposure.
Manual diagnostic radiology , by Jürgen Freyschmidt, Theodor Schmidt Online at Google Books