An image acquisition device enabling a dental radiological image to be obtained, the device comprising: a matrix sensor integrating: a plurality of image acquisition photodiodes that are integrated in the form of a matrix and are sensitive to radiation; and at least one detection photodiode that is distinct from the image acquisition photodiodes, integrated at the periphery of the matrix of the matrix sensor, and likewise sensitive to radiation; and a control module of the sensor adapted to periodically read the detection photodiode and to cause the sensor to switch between at least two modes: a standby mode in which the acquisition photodiodes are inhibited; and an acquisition mode in which the energy received by the acquisition photodiodes is used for the acquisition of an image; the switch being triggered as soon as the detection photodiode detects radiation from a generator, characterized in that the detection photodiode is suitable for supplying a periodic output signal to the control module, including during irradiation and image acquisition by the acquisition photodiodes, the periodic output signal having a value that is representative of the instantaneous received energy, and in that the control module uses this periodic output signal to analyze the energy received during acquisition, the control module being further suitable for modifying the resolution of the detection photodiode as a function of the output signal of the detection photodiode, in order to ensure that the detection photodiode does not saturate during the irradiation. a matrix sensor integrating: a plurality of image acquisition photodiodes that are integrated in the form of a matrix and are sensitive to radiation; and at least one detection photodiode that is distinct from the image acquisition photodiodes, integrated at the periphery of the matrix of the matrix sensor, and likewise sensitive to radiation; and a plurality of image acquisition photodiodes that are integrated in the form of a matrix and are sensitive to radiation; and at least one detection photodiode that is distinct from the image acquisition photodiodes, integrated at the periphery of the matrix of the matrix sensor, and likewise sensitive to radiation; and a control module of the sensor adapted to periodically read the detection photodiode and to cause the sensor to switch between at least two modes: a standby mode in which the acquisition photodiodes are inhibited; and an acquisition mode in which the energy received by the acquisition photodiodes is used for the acquisition of an image; the switch being triggered as soon as the detection photodiode detects radiation from a generator, characterized in that the detection photodiode is suitable for supplying a periodic output signal to the control module, including during irradiation and image acquisition by the acquisition photodiodes, the periodic output signal having a value that is representative of the instantaneous received energy, and in that the control module uses this periodic output signal to analyze the energy received during acquisition, the control module being further suitable for modifying the resolution of the detection photodiode as a function of the output signal of the detection photodiode, in order to ensure that the detection photodiode does not saturate during the irradiation.