a nuclear imaging system comprising : first and second radiation detectors , each comprising an imaging surface facing each other and each having an extent ; an radiation source , situated outside a space defined by a largest parallelepiped formed on two sides by said first and second detectors , which irradiates the second detector ; and an axis about which the first and second detectors and the radiation source rotate together ; wherein the field of view of the radiation source , defined by lines connecting the external source and the edges of the second detector , encompass the axis of rotation .