Back projection is one of the common mathematical algorithm that is used to reconstruct a slice of CT image based on projection of different angle. Figure 2.3 shows an example of CT image slice comprising of three different attenuation material namely soft tissue, bone and dense metal (contrast agent). Draw the projections you would see at =0 and =90 Back projection is one of the common mathematical algorithm that is used to reconstruct a slice of CT image based on projection of different angle. Figure 2.3 shows an example of CT image slice comprising of three different attenuation material namely soft tissue, bone and dense metal (contrast agent). Draw the projections you would see at =0 and =90