Discovery st elite performance

FDG PET/CT scan was performed using dedicated PET/CT scanners (Discovery ST Elite Performance; GE Healthcare). The SUV was normalized to body weight and injected dose. The baseline SUV_max was measured in all detected lesion, and the highest FDG uptake was considered as the SUV_max of the patient. The TMTV was defined as the sum of the volumes of all lymphoma‐associated voxels with SUV of ≥2.5, as previously described.²⁴ The TLG was calculated from the MTV and the mean SUV of all lesions. A semiquantitative analysis of the PET/CT scans for TMTV and TLG was performed using an open‐source software application Metavol (Hokkaido University).²⁵ Bone marrow uptake was calculated only if there was focal uptake. iPET was defined as PET/CT which was performed after two to four cycles of induction chemotherapy. Deauville 5‐PS was used for assessment of iPET, with a score of 4‐5 reflecting positivity.²⁶ We also analyzed quantitative SUV_max reduction between the baseline PET/CT and iPET by calculating the SUV_max decrease proportion (ΔSUV_max). All quantitative and volumetric parameters were retrospectively analyzed in a blinded fashion by a nuclear physician.

Positron Emission Tomography—Computed Tomography (PET/CT) System (Discovery ST Elite‐Performance, GE Healthcare, USA) and the Elekta Synergy linear accelerator (Elekta, Crawley, UK) were selected in this study. Three-dimensional conformal radiotherapy (3D-CRT) with 6 MV X-ray photons was used for standard pelvic external beam radiation. The external dose was 45–50 Gy, and the daily divided dose was 1.8–2.0 Gy. The radiation therapy was performed once a day, 5 days a week.
The areas of pelvic external beam radiation included 3–4 cm or higher above the vaginal stump, parauterine tissues, internal iliac lymph nodes, external iliac lymph nodes, obturator lymph nodes, presacral lymph nodes, and other lymph node drainage areas. If the lymph node was metastasized, the radiation field was expanded accordingly, including the common iliac lymph nodes and para-aortic lymph nodes. If the lower third of the vagina was invaded, the radiation field was expanded to the bilateral inguinal lymph nodes.

The subjects fasted for 2 h before the CT scan, which was performed using Discovery ST Elite Performance (GE Healthcare) according to the protocol of Teishinkai Central CI Clinic. The subjects were placed in a prone position inside the machine, with fists raised and breathing stopped. The fourth center of the lumbar spine was imaged with a slice thickness of 10 mm (tube voltage, 120 kvp; tube current, 150 mA; window width, 350; and window level, 35). The average radiation dose was 5 mSv per session. The images were analyzed using Fat Checker (J-MAC SYSTEM) to calculate the visceral fat area, total abdominal fat area, and subcutaneous abdominal fat area.