Chapter 9: Tomography

8 flashcards · Biology · by Kristóf Nagy

1. Maximum Likelihood Expectation Maximization (ML-EM)

   A statistical iterative reconstruction algorithm commonly used in tomography, aiming to find the most likely source distribution that would have created the measured projections, taking into account the statistical nature of photon detection26.

2. Iteration Procedure

   The step-by-step process of refining the image in an iterative reconstruction algorithm, involving comparing calculated and measured projections, updating the image based on the differences, and repeating the process until convergence27.

3. System Matrix

   A mathematical matrix that describes the relationship between the source distribution and the measured projections, encompassing all the factors that affect the imaging process, such as attenuation, scatter, detector sensitivity, and geometry27.

4. Convergence

   The process of an iterative algorithm approaching a stable solution where further iterations do not significantly improve the image quality26.

5. Backprojection

   A simpler reconstruction technique that directly assigns the measured projection values back to the corresponding voxels in the image, often leading to artefacts and blurring26.

6. Iterative Reconstruction

   An image reconstruction technique that starts with an initial guess of the image and iteratively refines it by comparing the calculated projections with the measured projections, aiming to minimize the difference between them26.

7. Sinogram

   A representation of the acquired data in tomography where the intensity of each projection is plotted as a function of projection angle and position, providing a visual representation of the data used for image reconstruction25.

8. Tomography

   A general imaging technique that reconstructs cross-sectional or 3D images of an object from multiple projections acquired from different angles, encompassing both CT and SPECT25.