Intevo bold

Imaging was performed at day 1, day 2 and day 6 using a Siemens Symbia Intevo Bold gamma camera. A planar scan of 100 cm was acquired starting from the base of the skull, using medium energy collimators and a 240 keV energy window, and a 5% upper and lower scatter window. Automatic body contouring was used, and the scan had a 20 min acquisition time. Large regions of interest (ROIs) were drawn with margins around the patient on both the anterior and posterior images, using 3D Slicer version 4.8.1, revision 26,813 (The Slicer Community). The geometric mean of the counts found in the anterior and posterior ROIs were then calculated.
During the gamma camera imaging sessions, a measurement using a scintillator probe, RadEye SX with an FHZ 514A scintillation probe (Thermo Fisher Scientific, Waltham, Massachusetts, United States) was taken 50 cm from the upper abdomen, on the right side of the patient. Background measurements were also performed, and subtracted from the patient measurement to obtain the number of counts at each time point.
To estimate the whole body effective half-life of ²²⁴Ra-CaCO₃-MP, three separate approaches were used. The gamma camera (the geometric means), SmartIon (the dose rates at 10 cm) and the RadEye (the number of counts). Separate mono-exponential curve fits and effective half-lives were calculated.

Biodistribution whole body planar and SPECT/CT imaging from the pelvis will be acquired at four, 24, and 120–168 h after administration of [¹⁷⁷Lu]Lu-PSMA-617 for our secondary endpoint: absorbed dose in the target lesions and in organs at risk. Imaging will be performed on Symbia T or Intevo Bold systems (Siemens GmbH, Erlangen, Germany), equipped with a Medium Energy General Purpose collimator. Total body scintigraphy will be acquired with both heads at 15 cm/min, 256 × 1024 matrix and energy windows around the main photopeaks: 208 keV ± 10% and 113 keV ± 10%. SPECT/CT of the pelvis will be acquired with triple energy windows (TEW) around both photopeaks: 208 keV ± 10% with an adjacent upper and lower scatter window of 16% width of the 208 keV peak, and 113 keV ± 10% with an adjacent upper and lower scatter window of 24% and 12% width of the 113 keV peak, respectively. SPECT acquisition parameters are non-circular, continuous rotations of both heads with 64 views of 20 s/view per head. The SPECT image matrix size is 128 × 128 with 4.8 mm cubic voxels. SPECT reconstruction includes attenuation and scatter corrected 3DOSEM (FLASH3D) with six iterations and eight subsets with five mm Gaussian post-reconstruction filtering. Local cross calibration between the gamma camera and dose calibrator was performed to enable quantitative measurements.