Notions of dosimetry

Message to remember: the effects of a radiation exposure are evaluated by the absorbed dose (D. dose). The equivalent dose (H. dose) reflects the probability variation of stochastic effects in accordance with the radiation nature. The efficient dose (E. dose) takes into account the difference of radiosensitivity to the stochastic effects of the different tissues or organs (T. organs). The optimization of the dose received by the patients in radiology requires the respect of the diagnosis reference level (N.R.D.) of the examination: dose at entry or dose.surface product in conventional radiodiagnosis, index of weighted CT scanning dose and dose.length product in CT scanning. (N.C.)