Attenuation-Emission Alignment in Cardiac PET/CT with Consistency Conditions
Misaligned attenuation correction factors lead to artifacts and quantitative errors in cardiac PET images, potentially resulting in inaccurate interpretation and/or incorrect clinical decisions. Artifacts from misaligned attenuation-emission scans are common with conventional PET imaging. The potential for misalignment/artifacts is further increased in dual modality PET/CT systems since CT images a snapshot of the respiratory cycle and PET images multiple respiratory cycles. In this work, we developed and tested a method for automated alignment of attenuation and emission data. The alignment process enforces the Radon consistency conditions on the emission data and is derived from previous work by Welch et al. The attenuation image volume is aligned through simple rigid body transformations with the emission data. We test the process with simulated data and measured patient data from two ammonia cardiac PET/CT exams.
A new estimator for a four-element plane array is introduced in order to get acoustic-passive direction estimation of targets.We concern much about the performance of the estimator under a two-target situation.In this paper,the two targets concerned are of the same type of acoustic source.Under different signal to interfere ratios,we propose the change of the precision of the direction estimation as the angle between the two targets changes.Our study was done under the real time Warfield situation,and may help the design of small acoustic-passive direction estimation arrays.