Method of calibrating a device for analysing an object, said analysis device including: - a source of irradiation adapted to irradiate said object, configured to emit ionizing electromagnetic radiation propagating towards the object along a propagation axis (12 z); - a detector including at least one pixel (20 k) and adapted to detect radiation (14 θ) diffused by the object irradiated in this way and to acquire an energy spectrum thereof, said diffused radiation (14 θ) propagating in a direction at an acute so-called diffusion angle (θ) relative to said propagation axis (12 z); the calibration method being characterized in that it includes the following steps: a) irradiation of a calibration object (10 c) by said irradiation source so that at least one pixel (20 k) of said detector detects radiation (14 θ) diffused by the calibration object (10 c) irradiated in this way and acquires an energy spectrum thereof; b) movement of the calibration object (10 c) to successive different positions ( z) along said propagation axis (12 z) and at each position acquisition by said pixel (20 k) of a spectrum S k, c, z E of the radiation diffused by said calibration object (10 c), termed a calibration spectrum, each calibration spectrum being associated with a position ( z) of the calibration object (10 c); c) in each calibration spectrum S k, c, z E acquired during the step b), identification of a characteristic calibration peak of said calibration object (10 c); d) determination of a parameter ( I k,c,z, E k,c,z) of the calibration peak identified in the step c); e) obtaining a dispersion function ( g k, h k, j k) associated with said pixel (20 k) from the parameters ( I k,c,z, E k,c,z) determined during the step d) at the various positions (z) of said calibration object (10 c), said dispersion function representing a dispersion of the intensity and/or the diffusion angle of diffused radiation (14 θ) detected by said pixel at the various positions (z) of the calibration object (10 c). - a source of irradiation adapted to irradiate said object, configured to emit ionizing electromagnetic radiation propagating towards the object along a propagation axis (12 z); - a detector including at least one pixel (20 k) and adapted to detect radiation (14 θ) diffused by the object irradiated in this way and to acquire an energy spectrum thereof, said diffused radiation (14 θ) propagating in a direction at an acute so-called diffusion angle (θ) relative to said propagation axis (12 z); the calibration method being characterized in that it includes the following steps: a) irradiation of a calibration object (10 c) by said irradiation source so that at least one pixel (20 k) of said detector detects radiation (14 θ) diffused by the calibration object (10 c) irradiated in this way and acquires an energy spectrum thereof; b) movement of the calibration object (10 c) to successive different positions ( z) along said propagation axis (12 z) and at each position acquisition by said pixel (20 k) of a spectrum S k, c, z E of the radiation diffused by said calibration object (10 c), termed a calibration spectrum, each calibration spectrum being associated with a position ( z) of the calibration object (10 c); c) in each calibration spectrum S k, c, z E acquired during the step b), identification of a characteristic calibration peak of said calibration object (10 c); d) determination of a parameter ( I k,c,z, E k,c,z) of the calibration peak identified in the step c); e) obtaining a dispersion function ( g k, h k, j k) associated with said pixel (20 k) from the parameters ( I k,c,z, E k,c,z) determined during the step d) at the various positions (z) of said calibration object (10 c), said dispersion function representing a dispersion of the intensity and/or the diffusion angle of diffused radiation (14 θ) detected by said pixel at the various positions (z) of the calibration object (10 c). a) irradiation of a calibration object (10 c) by said irradiation source so that at least one pixel (20 k) of said detector detects radiation (14 θ) diffused by the calibration object (10 c) irradiated in this way and acquires an energy spectrum thereof; b) movement of the calibration object (10 c) to successive different positions ( z) along said propagation axis (12 z) and at each position acquisition by said pixel (20 k) of a spectrum S k, c, z E of the radiation diffused by said calibration object (10 c), termed a calibration spectrum, each calibration spectrum being associated with a position ( z) of the calibration object (10 c); c) in each calibration spectrum S k, c, z E acquired during the step b), identification of a characteristic calibration peak of said calibration object (10 c); d) determination of a parameter ( I k,c,z, E k,c,z) of the calibration peak identified in the step c); e) obtaining a dispersion function ( g k, h k, j k) associated with said pixel (20 k) from the parameters ( I k,c,z, E k,c,z) determined during the step d) at the various positions (z) of said calibration object (10 c), said dispersion function representing a dispersion of the intensity and/or the diffusion angle of diffused radiation (14 θ) detected by said pixel at the various positions (z) of the calibration object (10 c).