Biograph classic

FDG PET/CT scans were performed at two institutions between 2003 and 2013. The ¹⁸F-FDG PET/CT imaging protocols used at both institutions were standardized throughout this time period and the details were published previously [17 (link)]. At one center, PET/CT imaging was performed on a Siemens Biograph Classic (Siemens Medical Solutions, Hoffman Estates, IL, USA) from 2003 to 2006 and on a Siemens Biograph T6 from 2006 to 2013. All PET/CT studies at another medical center were performed on a Siemens Biograph T6. FDG-PET/CT scanning was performed in a standardized fashion on a flat table top, with patients’ arms raised above the head in the treatment position. The CT images (5-mm slices) for the PET/CT study typically were obtained during shallow breathing. Emission PET images were obtained beginning 60 minutes after administration of 8–10 mCi of [¹⁸F]FDG. For the PET scan, the blood glucose level was required to be less than 150 mg/mL.
FDG-PET/CT images from the diagnostic radiology department were transferred to the Functional Image Analysis Tool (FIAT, in house system) and the UM-Plan system (in-house planning systems). Imaging data sets were co-registered according to anatomic match (CT of PET/CT registered to CT simulation based on CT anatomy).

Pre-treatment full body PET-CT scans were obtained in our nuclear medicine department in accordance with standard protocol for a majority of patients (51/57) on a Siemens Biograph Classic, Biograph T6 or Biograph 40 (Siemens Medical Solutions, Hoffman Estates, IL). Scans from the remaining six patients were obtained from outside institutions on either a Siemens Biograph Classic or GE ST/STE (GE Medical Systems, GE Healthcare, Chicago, IL). All 3-month post-treatment imaging was performed within our institution. Parotid glands were manually contoured by a Radiation Oncology MD on all pre-treatment CT scans in our treatment planning system (Aria, Varian Medical Systems). The contours were copied to the registered PET scan, and deformable registration (SmartAdapt, Varian Medical Systems) was used to copy the contours to the 3-month CT and PET scans. The deformed contours were visually inspected for accuracy and manually adjusted as needed (2 cases).