Photon Intensity Tomography X-ray CT SPECT PET X-ray source distribution of source distribution of measuring attenuation radio-pharmaceuticals,radio-pharmaceuticals,gamma emitters positron emitters anatomical Yes NoNo information beam definition collimators collimators coincidence detection Photon Intensity Tomography X- ray CT SPECT PET X- ray source distribution of source distribution of measuring attenuation radio- pharmaceuticals, radio- pharmaceuticals,gamma emitters positron emitters anatomical Yes No No information beam definition collimators collimators coincidence detection