1. An apparatus for single photon emission computed tomography (SPECT) imaging, comprising: a robotic arm, movable in three rotational degrees of freedom, comprising a base end and a distal end, the distal end configured to support a plurality of SPECT imaging detectors; and a patient support assembly, movable in a linear degree of freedom; and a controller, configured to cause the robotic arm to move the plurality of SPECT imaging detectors, in three dimensions, around a patient's body to obtain SPECT images, and cause the patient support assembly to move along the linear degree of freedom, to maintain alignment of the patient's body with the plurality of SPECT imaging detectors.