Tomography reconstructs an interior distribution from measurements along multiple lines or paths through it. A linear unattenuated model is the Radon transform; absorption changes it to an attenuated Radon transform.
Tomography using approximately coincident annihilation-photon detections to constrain an internal emission distribution. A calibrated model accounts for propagation, detector response, unrelated coincidences and scattering.
A pair of nearly simultaneous detector events treated as a candidate two-photon positron annihilation. True unscattered pairs define a coincidence line of response. For attenuation along one such line, the complementary survival path integrals add to the full chord and are independent of the annihilation depth.
The distance between positron emission and annihilation. Its distribution introduces a blur even if the subsequent line of response is measured perfectly.
Coincidence imaging using the detection-time difference to estimate annihilation position along a line of response. For timing difference , displacement from the midpoint is .
The line joining two coincident photon detections in ideal two-photon annihilation imaging. Finite detector size, non-collinearity and positron travel limit its relation to the original decay position.
A line defined by an approximately coincident detector pair in annihilation-photon tomography. An event constrains a possible annihilation location to that line within instrumental and physical uncertainties. Time-of-flight data can add a position constraint along it; attenuation, scattering and random coincidences change the forward model.
Transmission measurements determine line integrals of an absorption coefficient after taking the logarithm of incident intensity divided by transmitted intensity. Under the ideal straight-ray model, these measurements are a Radon transform; filtered backprojection reconstructs a planar slice. Angular coverage, calibration and noise control matter because differentiating measured projections amplifies high frequencies. In contrast, single-photon emission computed tomography reconstructs an emitting source through a possibly attenuating medium.
A dimensionless relative attenuation value calibrated so that water is zero and air is approximately . It depends on the computed tomography spectrum and material composition. It is not directly a linear attenuation coefficient at the energy used in positron emission tomography.
X-ray tomography at a scale that can resolve small skeletal features without destroying a specimen. Segmentation and resolution constrain anatomical interpretation.
A form of tomography that reconstructs an internal radioactive source from directional counts of individually emitted photons. Known spatial photon absorption gives the exponential path weight in an attenuated Radon transform. Full directed data and a suitable reconstruction formula recover the source intensity rather than a transmitted exterior-beam attenuation map.
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Tomography is an imaging technique used to create detailed internal images of an object, typically a body or an organ. It involves taking cross-sectional images, or slices, of the object from different angles. This technique allows for the visualization of internal structures without requiring invasive procedures.
