Figure 3

Reconstructed tomograms from the PET1 data set using three different reconstruction methods based on 30% sampling. The PET1 data set was taken from a 73 year-old man who sought medical attention due to a grand mal seizure and progressive speech difficulties, with a brain biopsy revealing grade II astrocytoma. It can be observed that the reconstructed tomogram using the FBP method exhibits the most significant artifacts (both in the background area and the imaged brain area), when compared to TVR and the proposed HNLR methods. The reconstructed tomogram using the TVR method exhibits significantly reduced but still noticeable artifacts in the background area, and no artifacts in the imaged brain area. However, there is noticeable loss in fine detail in the imaged brain area. Finally, the reconstructed tomogram using the proposed HNLR method exhibits the least amount of artifacts in the background area when compared to FBP and TVR, no artifacts in the imaged brain area, and noticeably better preservation of fine detail in the imaged brain area.