Method for determining a spatial-sensitivity function of a gamma camera, the gamma camera being configured to locate radiation sources in a field of observation (Ω), the field of observation being liable to contain radiation sources, the gamma camera comprising: - a detector material; - pixels, distributed over a detecting area of the detector material, each pixel being configured to form a detection signal under the effect of detection of an interaction of an ionising photon in the detector material; - a unit for achieving sub-pixel resolution, said unit being programmed to assign, to each detected interaction, a position (x,y) parallel to the detecting area, on the basis of detection signals formed by a plurality of pixels, the position being determined on a mesh of the detecting area that divides each pixel into a plurality of virtual pixels (13 ij), the virtual pixels being distributed in rows and columns; - a memory, configured to store a quantity of interactions ( G ( x,y), G E ( x, y)) detected in the course of an acquisition period and respectively assigned to each virtual pixel; the method comprising the following steps: - a) acquiring detection signals with the pixels during one acquisition period, each detection signal being associated with one detected interaction; - b) depending on the detection signals, attributing a position (x,y) of each interaction detected, during the acquisition period, to one virtual pixel; - c) storing, in the memory, a number of detected interactions assigned to each virtual pixel (13 ij); the method being characterized in that it comprises, following step c), - d) defining groups of virtual pixels, each group containing a plurality of virtual pixels ( G ( x,y), G F ( x,y)); - e) computing a value for each group ( H x ( y), H Y ( x), H' ( x j', y j)), the value of each group being computed on the basis of a sum of the number of interactions positioned in each virtual pixel belonging to said group, - f) on the basis of the value computed for each group, assigning a weight (H(x, y)) to each virtual pixel, the weight assigned to each virtual pixel being representative of a detection sensitivity of said virtual pixel, all of the weights respectively assigned to each virtual pixel forming the spatial-sensitivity function of the gamma camera. - a detector material; - pixels, distributed over a detecting area of the detector material, each pixel being configured to form a detection signal under the effect of detection of an interaction of an ionising photon in the detector material; - a unit for achieving sub-pixel resolution, said unit being programmed to assign, to each detected interaction, a position (x,y) parallel to the detecting area, on the basis of detection signals formed by a plurality of pixels, the position being determined on a mesh of the detecting area that divides each pixel into a plurality of virtual pixels (13 ij), the virtual pixels being distributed in rows and columns; - a memory, configured to store a quantity of interactions ( G ( x,y), G E ( x, y)) detected in the course of an acquisition period and respectively assigned to each virtual pixel; - a) acquiring detection signals with the pixels during one acquisition period, each detection signal being associated with one detected interaction; - b) depending on the detection signals, attributing a position (x,y) of each interaction detected, during the acquisition period, to one virtual pixel; - c) storing, in the memory, a number of detected interactions assigned to each virtual pixel (13 ij); - d) defining groups of virtual pixels, each group containing a plurality of virtual pixels ( G ( x,y), G F ( x,y)); - e) computing a value for each group ( H x ( y), H Y ( x), H' ( x j', y j)), the value of each group being computed on the basis of a sum of the number of interactions positioned in each virtual pixel belonging to said group, - f) on the basis of the value computed for each group, assigning a weight (H(x, y)) to each virtual pixel, the weight assigned to each virtual pixel being representative of a detection sensitivity of said virtual pixel, all of the weights respectively assigned to each virtual pixel forming the spatial-sensitivity function of the gamma camera.