title: Ectomography--a tomographic method for gamma camera imaging.
abstract: In computerised gamma camera imaging the projections are readily obtained in digital form, and the number of picture elements may be relatively few. This condition makes emission techniques suitable for ectomography--a tomographic technique for directly visualising arbitrary sections of the human body. The camera rotates around the patient to acquire different projections in a way similar to SPECT. This method differs from SPECT, however, in that the camera is placed at an angle to the rotational axis, and receives two-dimensional, rather than one-dimensional, projections. Images of body sections are reconstructed by digital filtration and combination of the acquired projections. The main advantages of ectomography--a high and uniform resolution, a low and uniform attenuation and a high signal-to-noise ratio--are obtained when imaging sections close and parallel to a body surface. The filtration eliminates signals representing details outside the section and gives the section a certain thickness. Ectomographic transverse images of a line source and of a human brain have been reconstructed. Details within the sections are correctly visualised and details outside are effectively eliminated. For comparison, the same sections have been imaged with SPECT.
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging*; D006801:Humans; D011877:Radionuclide Imaging / Q000295:instrumentation / Q000379:methods*; D014055:Tomography, Emission-Computed / Q000295:instrumentation / Q000379:methods*