Detection apparatus for detecting high energy radiation, preferably for detecting gamma radiation, coming from a source of high energy radiation in a detection volume, e.g. from one or more particles emitting high energy radiation, said apparatus comprising: - at least three position sensitive cameras, each camera comprising: - at least one position sensitive detector (13-1,13-2,13-3) having a detection surface and being configured to convert high energy radiation incident on said detection surface into a detection signal including position information of incident radiation, and - a collimator slit arranged to project high energy radiation coming from a respective slit field of view of said detection volume as a line-shaped irradiation onto said detection surface, wherein two collimator slits (12-1,12-3) of said three collimator slits (12-1,12-2, 12-3) extend perpendicular to one another and a third collimator slit (12-2) parallel to one of said two perpendicular collimator slits establishing an x-axis, y-axis, and z-axis that are orthogonal to one another, wherein the respective slit fields of view of said at least three collimator slits (12-1,12-2,12-3) overlap and define a common detection volume (C) of the detection apparatus, - a processing unit, adapted, e.g. programmed, to determine a value of at least one coordinate along each of said x-axis, y-axis, and z-axis for said source of high energy radiation on the basis of the incident radiation position on the detection surface and to reconstruct a position of said source of high energy radiation in said common detection volume (C) on the basis of said detection signals. - at least three position sensitive cameras, each camera comprising: - at least one position sensitive detector (13-1,13-2,13-3) having a detection surface and being configured to convert high energy radiation incident on said detection surface into a detection signal including position information of incident radiation, and - a collimator slit arranged to project high energy radiation coming from a respective slit field of view of said detection volume as a line-shaped irradiation onto said detection surface, wherein two collimator slits (12-1,12-3) of said three collimator slits (12-1,12-2, 12-3) extend perpendicular to one another and a third collimator slit (12-2) parallel to one of said two perpendicular collimator slits establishing an x-axis, y-axis, and z-axis that are orthogonal to one another, wherein the respective slit fields of view of said at least three collimator slits (12-1,12-2,12-3) overlap and define a common detection volume (C) of the detection apparatus, - at least one position sensitive detector (13-1,13-2,13-3) having a detection surface and being configured to convert high energy radiation incident on said detection surface into a detection signal including position information of incident radiation, and - a collimator slit arranged to project high energy radiation coming from a respective slit field of view of said detection volume as a line-shaped irradiation onto said detection surface, wherein two collimator slits (12-1,12-3) of said three collimator slits (12-1,12-2, 12-3) extend perpendicular to one another and a third collimator slit (12-2) parallel to one of said two perpendicular collimator slits establishing an x-axis, y-axis, and z-axis that are orthogonal to one another, wherein the respective slit fields of view of said at least three collimator slits (12-1,12-2,12-3) overlap and define a common detection volume (C) of the detection apparatus, - a processing unit, adapted, e.g. programmed, to determine a value of at least one coordinate along each of said x-axis, y-axis, and z-axis for said source of high energy radiation on the basis of the incident radiation position on the detection surface and to reconstruct a position of said source of high energy radiation in said common detection volume (C) on the basis of said detection signals. <EOS>