What phase uses simple back projection as a method of building up the CT image in the computer?

• A. Reconstruction phase
• B. Acquisition phase
• C. Image analysis phase
• D. Display phase

Answer: (A)

The correct choice highlights the reconstruction phase, which is where the raw data collected during the acquisition phase is processed to create the final image. In CT imaging, back projection is a technique used to convert the data obtained from multiple angles into a two-dimensional image. During the reconstruction phase, the computer takes the projections from different angles and mathematically processes them to construct the cross-sectional images of the body.

Back projection involves taking the projection data and distributing it back along the paths from which they were recorded, effectively "projecting" it backward into the image space to create a visual representation. This process is fundamental in forming a coherent image from the various data points provided by the CT scanner.

The other phases refer to different aspects of the imaging process. The acquisition phase involves collecting the raw data as the CT scanner rotates around the patient. The image analysis phase focuses on interpreting the images for diagnostic purposes, while the display phase involves presenting the reconstructed images for review. Each phase has its distinct function, but the use of simple back projection specifically occurs during the reconstruction phase, making this the correct answer.