The correct option is (4), Pixel size, Slice thickness, and the Reconstruction algorithm used have an effect on the contrast.
Which parameters affects the contrast of a CT image?
The important parameters in CT images are:
Pixel size: The size of the pixels in the image matrix can influence the spatial resolution and, consequently, the image contrast. Smaller pixels can provide higher spatial resolution, potentially enhancing the visibility of smaller structures and improving contrast.
Slice thickness: The thickness of the CT slices impacts the ability to differentiate structures in the z-axis (along the length of the body). Thinner slices can provide better z-axis resolution, potentially improving contrast by reducing partial volume effects.
Reconstruction algorithm: The choice of reconstruction algorithm during the image processing stage can significantly impact image quality, including contrast. Different algorithms may emphasize certain features or reduce artifacts, influencing how structures are visualized in the final image.
So all of the options have influence in the contrast of CT images.