1. A radioactive-emission-measurement system, comprising: a camera for the detection of single emissions, which defines proximal and distal ends, with respect to an operator, the camera being configured for detecting at least 1 of every 5000 photons, emitted from at least one radioactive-emission source, located within a region-of-interest volume; and a data-processing system, configured for reconstructing a radioactive-emission image from detected photons, wherein given a substantially line source of radioactive emission, with an activity of 5 mCi, located within the region-of-interest volume, at a distance of at least 100 mm from the distal end of the camera, with air being substantially the only operating medium, a reconstructed image of the line source has a line spread function, which is less than 7 mm Full Width Half Maximum (FWHM).