PET-Guided SCINTIX System Shows Promise in Real-Time, Adaptive Radiotherapy for Lung and Bone Tumors
New research presented at the 2025 Society of Nuclear Medicine and Molecular Imaging Annual Meeting highlights the successful use of SCINTIX, a PET-guided radiotherapy system, to tailor radiation delivery using real-time biological data in patients with lung and bone tumors.
In this early clinical experience, 14 patients received a total of 54 radiotherapy fractions using the SCINTIX platform. Across treatment sessions, researchers observed a general decrease in tumor activity concentration (AC), which began at 61.3 kBq/mL and dropped progressively to 33.49 kBq/mL by the fifth fraction. Normalized target signal (NTS) values similarly declined from 36.23 to 18.13, while tumor volumes were also reduced, from 14,355 mm³ to 3,391 mm³ over the course of treatment.
One highlighted case involved a patient with a lower spine bone tumor who underwent a single 12 Gy radiotherapy session. The patient’s standard uptake value (SUV) was 7, AC was 29.85 kBq/mL, and NTS was 17. The planning target volume (PTV) coverage was 97.6%, and dose constraints for surrounding organs—such as 8 Gy to the bowel and 12 Gy to the cauda equina—were all safely met. The treatment was completed in 29 minutes.
In a separate case involving a lung tumor, Rameshwar Prasad, PhD, emphasized the platform’s potential to significantly reduce PTV by using biological data to avoid unnecessary radiation to nearby healthy tissues.
“We can include the biological information for the planning as well as the delivery of high-beam [radiotherapy]. We successfully treated the lung and bone tumors on the real-time PET signal, which guided our planning and the delivery,” said Prasad, associate professor of radiation oncology and faculty member in the Department of Radiation Oncology’s Division of Medical Physics & Engineering at the University of Texas Southwestern Medical Center. “I personally feel there's a lot of potential in this system. However, we really need more trials and continued work, especially on the technical and the clinical front.”
SCINTIX differs from conventional radiotherapy, which typically depends on static pretreatment images from CT, MRI, or PET scans. These traditional methods don’t adapt to tumor motion or changing biological activity during treatment and often carry a risk of irradiating healthy tissue due to setup limitations.
The SCINTIX platform uses 64 detectors arranged in two arcs to continuously capture PET emissions throughout treatment. This real-time PET subsystem supports biology-guided radiotherapy (BgRT) by using two key metrics: activity concentration (AC), which reflects signal strength for treatment guidance, and normalized target signal (NTS), which measures contrast between the tumor and surrounding tissue.
In total, 27 patients were evaluated for BgRT, and 14 went on to receive treatment with SCINTIX. All treatment fractions were administered without interruption or adverse events, and every plan was delivered as intended, demonstrating the system’s feasibility and clinical potential.