SU‐C‐206‐07: A Practical Sparse View Ultra‐Low Dose CT Acquisition Scheme for PET Attenuation Correction in the Extended Scan Field‐Of‐View

Abstract

Purpose:To further reduce CT dose, a practical sparse‐view acquisition scheme is proposed to provide the same attenuation estimation as higher dose for PET imaging in the extended scan field‐of‐view.Methods:CT scans are often used for PET attenuation correction and can be acquired at very low CT radiation dose. Low dose techniques often employ low tube voltage/current accompanied with a smooth filter before backprojection to reduce CT image noise. These techniques can introduce bias in the conversion from HU to attenuation values, especially in the extended CT scan field‐of‐view (FOV). In this work, we propose an ultra‐low dose CT technique for PET attenuation correction based on sparse‐view acquisition. That is, instead of an acquisition of full amount of views, only a fraction of views are acquired. We tested this technique on a 64‐slice GE CT scanner using multiple phantoms. CT scan FOV truncation completion was performed based on the published water‐cylinder extrapolation algorithm. A number of continuous views per rotation: 984 (full), 246, 123, 82 and 62 have been tested, corresponding to a CT dose reduction of none, 4x, 8x, 12x and 16x. We also simulated sparse‐view acquisition by skipping views from the fully‐acquired view data.Results:FBP reconstruction with Q. AC filter on reduced views in the full extended scan field‐of‐view possesses similar image quality to the reconstruction on acquired full view data. The results showed a further potential for dose reduction compared to the full acquisition, without sacrificing any significant attenuation support to the PET.Conclusion:With the proposed sparse‐view method, one can potential achieve at least 2x more CT dose reduction compared to the current Ultra‐Low Dose (ULD) PET/CT protocol. A pre‐scan based dose modulation scheme can be combined with the above sparse‐view approaches, which can even further reduce the CT scan dose during a PET/CT exam.