Symbia intevo bold

[⁶⁸Ga]Ga-PSMA-PET/CT imaging was performed on a Biograph mCT system (Siemens Healthineers, Erlangen, Germany) 1 week prior to each administration of [¹⁷⁷Lu]Lu-PSMA to evaluate PSMA-positive tumor lesions, following local clinical acquisition protocols [30 (link)]. Standardized uptake values (SUV) were determined for salivary gland (SUV_mean, spherical volumes of interest (VOIs) of 20 mm in diameter) and lesions (SUV_max). For dosimetry, all patients received SPECT/CT imaging at 1, 24, 48, 72, and 168 h after each therapy on either a Symbia T16 or Symbia Intevo Bold system (Siemens Healthineers, Erlangen, Germany). Both systems were cross-calibrated for ¹⁷⁷Lu with the in-house dose calibrator, which undergoes regular quality control according to national guidelines [31 ]. Three-bed position SPECT/CT scans were acquired including the pelvis, abdomen, and head/neck region. The acquisition and reconstruction protocol was followed as described by Peters et al. [32 (link)] and was in accordance with MIRD pamphlet no. 26 [33 (link)]. These protocols take into account scatter, attenuation, and dead-time corrections.

Imaging acquisition was performed on a double-head gamma-camera equipped with low-energy high-resolution (LEHR) collimators (Siemens Symbia Intevo Bold). After injection of 555 MBq (15 mCi) of 99mTc- MIBI, early and delayed parathyroid scans were obtained 15 min (min) and 2 h (h) after the injection, respectively. Anterior neck images were obtained in a 256 × 256 matrix, gathering 500 k counts per position, with a 20% energy window centered on the 140 keV photopeak after 15 min and 2 h. SPECT/CT imaging was performed immediately after both the early and delayed planar images. During the SPECT study, 30 stops were acquired, with 20 s acquisition time per frame and a matrix of 256 × 256 pixels. CT images were acquired with the tube voltage set at 100 kV, tube current determined by automatic dose modulation with a set reference current of 60 mAs.

Each patient was injected with [^99mTc]Tc-ADAPT6, followed by injection with [^99mTc]Tc-(HE)₃-G3 after 3–4 days. In patient 1, the interval between injection was 15 days.
The injected protein masses and timing of imaging were selected based on the results of previous Phase I studies [9 (link),10 (link)]. The injected protein masses were 500 and 3000 µg for [^99mTc]Tc-ADAPT6 and [^99mTc]Tc-(HE)₃-G3, respectively. [^99mTc]Tc-ADAPT6 (523 ± 211 MBq) and [^99mTc]Tc-(HE)₃-G3 (443 ± 185 MBq) were injected intravenously. Imaging was performed using a Siemens Symbia Intevo Bold scanner equipped with a high-resolution low-energy collimator. SPECT/CT scans (SPECT: 60 projections, 20 s each, stored in 256 × 256 pixel matrix/CT: 130 kV, effective 36 mAs) were performed 2 h after injection for [^99mTc]Tc-ADAPT6 and 4 h after injection for [^99mTc]Tc-(HE)₃-G3 in all patients. SPECT images were reconstructed using a reconstruction xSPECT (Siemens) protocol based on the ordered subset conjugate gradient (OSCG) method (24 iterations, 2 subsets). The 3D Gaussian FWHM 10 mm filter (Soft Tissue) was used. The images were processed using the proprietary software package Syngo.via (Siemens).

In a third-line academic institute (Radboudumc, the Netherlands), two prospective clinical studies were conducted on PSMA-RLT in cancer patients with PSMA-positive disease and an adequate glomerular filtration rate (GFR) (≥50 mL/min). Both studies used an identical dosimetry protocol. One study applied a first cycle of 3 GBq and a second cycle (after 6 weeks) of ~6 GBq [¹⁷⁷Lu]Lu-PSMA-617 in ten low-volume metastatic hormone-sensitive prostate cancer (mHSPC) patients, thus in total a cumulative activity of ~9 GBq [7 (link)]. The other used ~7.4 GBq [¹⁷⁷Lu]Lu-PSMA-I&T in 10 advanced SGC patients (NCT04291300). The dosimetry protocol of both trials consisted of five time points (1 h, 24 h, 48 h, 72 h, and 168 h) 3D SPECT/CT imaging post [¹⁷⁷Lu]Lu-PSMA injection. All scans were acquired on a Symbia T16 or Symbia Intevo Bold system (Siemens Healthineers, Erlangen, Germany) using a medium-energy low-penetration collimator, a 20% photon energy window at 208 keV with dual-energy window for Compton scattering, 64 projections per detector and 14 s per projection, matrix size 128 × 128 and zoom 1. Data were reconstructed using ordered subsets maximization expectation reconstruction (Flash 3D with collimator detector response) using four iterations, eight subsets and a smoothing Gaussian filter of 8.4 mm.

Patients received [⁶⁸Ga]Ga-PSMA-11-PET/CT approximately 1 week prior to radioligand therapy. Imaging was performed 60 ± 10 min post-injection on a Biograph mCT system (Siemens Healthineers, Erlangen, Germany) scanning cranium to trochanter major. Patients received a therapeutic activity of 3 GBq (3057 ± 38 MBq) [¹⁷⁷Lu]Lu-PSMA-617. This relatively low activity was chosen because it was part of a prospective pilot study in a patient population that did not receive this type of treatment before. The preparation of [¹⁷⁷Lu]Lu-PSMA was described previously [25 ] and can be found in Online Resource 2. SPECT/CT imaging was performed at 1, 24, 48, 72, and 168 h after administration on either a Symbia T16 or Symbia Intevo Bold system (Siemens Healthineers, Erlangen, Germany). SPECT/CT scans were acquired at three body regions: pelvis, abdomen, and head-neck regions. Acquisition and reconstruction parameters can be found in Online Resource 3.