[en] The dosimetry objective in the radiological image is the quantification from the exposition to the radiation with a commitment of optimizing the image quality to the reason of the absorbed dose. The dosimetry has the meaning of avoiding excessive dose that could imply a significant risk of deterministic effects induction. The dosimetric magnitudes and dosimetry protocols in the radiological image, are those that are related to the risks for the patient. Exist in diagnostic radiology two fundamentals reason to measure or to estimate the patient radiation dose. First, the mensurations are a means to verify the good practices and an aid to the optimization of the patient protection. Second, the absorbed dose estimation to tissues and organs in the patient are necessary to determine the risks, and this way to indicate that the radiological techniques employees can be justified and in investigated cases of over exposition. (Author)