Abstract
323
Objectives: Average CT (ACT) has been shown to be effective in improving registration between CT and PET data in PET/CT (Pan et al, JNM 05). We proposed and designed an ACT (called MDA-ACT) for all GE PET/CT scanners and compared it with the new GE-ACT implemented on the Dimension console available in the GE DSTE PET/CT scanner. Methods: We utilized the cine CT scan in GE PET/CT to generate high-temporal resolution CT images in the thorax over a respiratory cycle for depicting tumors in respiratory motion. The cine CT images are averaged and fused with the images above and below the thorax in the helical CT (HCT) data to become ACT for attenuation correction (AC) of the PET data. This implementation only needs a computer for the MDA-ACT software. In addition to the standard pair of HCT and PET-HCT (AC with HCT), MDA-ACT provides the pair of ACT and PET-ACT (AC with ACT) for registration. Physicians can bring up the two pairs of PET-CT data for interpretation at the same time. GE-ACT requires the cine CT data to be taken before the PET scan, and it averages the cine CT images with the HCT data for AC of the PET data. MDA-ACT only averages the cine CT images to avoid the misaligned HCT data in ACT. GE-ACT only provides a mixed set of CT images of HCT and cine CT, and PET-ACT. No ACT is generated in GE-ACT. Results: In CT dose, MDA-ACT allows ACT be acquired after the PET scan during which misregistration in the thorax can be identified and a decision to acquire ACT can be made so that radiation dose to the patients who do not need ACT can be saved. GE-ACT requires the cine CT be taken before the PET scan. In availability, MDA-ACT can be implemented on any GE PET/CT with a software addition. GE-ACT is only available on the new GE Dimension console. In workflow, the fused ACT in MDA-ACT is easier for interpretation with PET-ACT by physicians than the mixed set of HCT and cine CT images in GE-ACT. We have performed over 500 ACT’s with the MDA-ACT over four GE PET-CT scanners and no delay in workflow was found. Conclusions: We have implemented the MDA-ACT on the platform for all GE PET/CT scanners. MDA-ACT currently is better than GE-ACT in dose, availability, and workflow.
- Society of Nuclear Medicine, Inc.