1. A system comprising: one or more transmitters to transmit an excitation energy into an object under observation; one or more detectors to generate projection space data encoding an energy received by the one or more detectors in response to the transmitted excitation energy into the object under observation; a controller to control the one or more transmitters to transmit the excitation energy and the one or more detectors to generate the projection space data; and an image reconstructor to receive the projection space data and to process the projection space data by: computing a first quantity for each of a plurality of object space voxels, the first quantity characterizing a logarithm of a ratio between a value of the projection space data and a corresponding value of predicted projection data; computing a second quantity for each of the plurality of object space voxels, the second quantity corresponding to at least one inverted impulse response combined with contributions from a noise variance, each impulse response corresponding to a reference voxel of unit-intensity, the second quantity computed using the contributions from the noise variance and at least one of a Kalman filter gain, an approximate Kalman filter gain, a Wiener filter gain, or an approximate Wiener filter gain; computing an update value for each of the plurality of object space voxels, each update value computed using the corresponding first quantity and the corresponding second quantity; and reconstructing an object space image representing the object under observation using the update values.