A method for estimating a dose rate, on the basis of measurements taken by a gamma camera, the gamma camera defining an observation field (Ω), the method being such that: - the estimated dose rate originates from irradiating sources (10 a, 10 b) located in the observation field, the irradiating sources emitting ionizing electromagnetic radiation; - the observation field is discretized into a mesh; - the gamma camera comprises pixels (2 j), each pixel being configured to detect the ionizing electromagnetic radiation, during an acquisition time, and to form an energy spectrum therefrom, each pixel being associated with at least one point of the mesh, such that together the pixels allow a position of the irradiating sources in the observation field to be obtained in one energy band ( E i) or in a plurality of energy bands); the method comprising the following steps: a) acquiring spectra ( M j) with the pixels; b) taking into account an emission spectrum ( S k), the emission spectrum being defined in one or more energy bands ( E i); c) selecting points (x,y) of the mesh; d) on the basis of the spectra ( M j) acquired by each pixel (2 j), estimating a spatial distribution of an activity ( O k ( x,y)), corresponding to the emission spectrum taken into account in step b), for the selected points of the mesh; e) in each energy band ( E i) of the emission spectrum, taking into account a preestablished conversion function ( D i) relating a dose rate to a photon flux detected by the gamma camera; f) on the basis of the conversion function ( D i) resulting from step e), and of the spatial distribution of activity ( O k ( x, y)) determined in step d), estimating a dose rate () generated, at the gamma camera, by the points selected in step c); wherein step d) comprises, in each energy band ( E i) of the emission spectrum, and for each pixel: - estimating a photon flux ( M̂) detected by the pixel in the energy band, depending on a spatial distribution of the activity of the selected points of the mesh; - on the basis of the spectrum detected by the pixel ( M j), determining, in the energy band, the photon flux ( M i,j) detected by the pixel; step d) comprising, in each energy band, and for each pixel, minimizing a discrepancy between the estimated photon flux and the measured photon flux. g) - the estimated dose rate originates from irradiating sources (10 a, 10 b) located in the observation field, the irradiating sources emitting ionizing electromagnetic radiation; - the observation field is discretized into a mesh; - the gamma camera comprises pixels (2 j), each pixel being configured to detect the ionizing electromagnetic radiation, during an acquisition time, and to form an energy spectrum therefrom, each pixel being associated with at least one point of the mesh, such that together the pixels allow a position of the irradiating sources in the observation field to be obtained in one energy band ( E i) or in a plurality of energy bands); the method comprising the following steps: a) acquiring spectra ( M j) with the pixels; b) taking into account an emission spectrum ( S k), the emission spectrum being defined in one or more energy bands ( E i); c) selecting points (x,y) of the mesh; d) on the basis of the spectra ( M j) acquired by each pixel (2 j), estimating a spatial distribution of an activity ( O k ( x,y)), corresponding to the emission spectrum taken into account in step b), for the selected points of the mesh; e) in each energy band ( E i) of the emission spectrum, taking into account a preestablished conversion function ( D i) relating a dose rate to a photon flux detected by the gamma camera; f) on the basis of the conversion function ( D i) resulting from step e), and of the spatial distribution of activity ( O k ( x, y)) determined in step d), estimating a dose rate () generated, at the gamma camera, by the points selected in step c); a) acquiring spectra ( M j) with the pixels; b) taking into account an emission spectrum ( S k), the emission spectrum being defined in one or more energy bands ( E i); c) selecting points (x,y) of the mesh; d) on the basis of the spectra ( M j) acquired by each pixel (2 j), estimating a spatial distribution of an activity ( O k ( x,y)), corresponding to the emission spectrum taken into account in step b), for the selected points of the mesh; e) in each energy band ( E i) of the emission spectrum, taking into account a preestablished conversion function ( D i) relating a dose rate to a photon flux detected by the gamma camera; f) on the basis of the conversion function ( D i) resulting from step e), and of the spatial distribution of activity ( O k ( x, y)) determined in step d), estimating a dose rate () generated, at the gamma camera, by the points selected in step c); wherein step d) comprises, in each energy band ( E i) of the emission spectrum, and for each pixel: - estimating a photon flux ( M̂) detected by the pixel in the energy band, depending on a spatial distribution of the activity of the selected points of the mesh; - on the basis of the spectrum detected by the pixel ( M j), determining, in the energy band, the photon flux ( M i,j) detected by the pixel; - estimating a photon flux ( M̂) detected by the pixel in the energy band, depending on a spatial distribution of the activity of the selected points of the mesh; - on the basis of the spectrum detected by the pixel ( M j), determining, in the energy band, the photon flux ( M i,j) detected by the pixel; step d) comprising, in each energy band, and for each pixel, minimizing a discrepancy between the estimated photon flux and the measured photon flux. g)