Study of Image Contrast Recovery Coefficient (CRC) of a Large Ring PET Scanner

Image contrast recovery coefficient (CRC) of a large ring PET scanner “macroPET” was studied with septa and without septa configuration by ac-quiring data from a laboratory made 35.7 cm square phantom filled with 18-F. Images were reconstructed with simple 2D filtered back projection using Hann, Hamming and Parsen filters with different cut-off frequencies aiming to investigate the influence of filter and cut-off frequency on image contrast with septa and without septa mode. Results indicate that the CRC, for both hot and cold lesions, is excellent for diameters ≥ 3 cm using cut-off frequencies > 0.4. For a 2 cm hot lesion CRC is around 0.8 to 0.9. CRC for 1 cm hot and cold lesions is ~0.3, as expected. There is surprisingly little difference between results with and without septa. For hot lesions, septa appear to improve CRC slightly, but for cold lesions CRC is slightly poorer using septa.