2299 - Clinical Implementation of SCINTIX Biology-Guided Radiotherapy: A Single Institution Experience from Initial Patient Selection to First SCINTIX Delivery

C. Han, W. T. Watkins, A. Amini, S. M. Glaser, S. V. Dandapani, S. Yoon, Y. R. Li, J. Y. C. Wong, T. M. Williams, S. Sampath, and A. Liu; Department of Radiation Oncology, City of Hope National Medical Center, Duarte, CA

Purpose/Objective(s): The SCINTIX treatment technique on the medical technology company machine became clinically available in 2023. With integrated positron emission tomography (PET) imaging system, the machine uses real-time positron emission signals from the fludeoxyglucose F-18 (FDG)-avid tumor as a bio-guide for accurate radiation delivery. This study reviews our institutional experience in patient selection and treatment planning in the early phase of initiating clinical SCINTIX treatments with aim of facilitating other institutions in implementing this technology. Materials/

Methods: After commissioning SCINTIX hardware and software modules on the medical technology company machine at our institution in 2023, we implemented a process of prospective patient screening for SCINTIX treatment eligibility. Potentially eligible patients were further evaluated with quantitative measures by physics team. Eligibility criteria included availability of recent diagnostic PET/CT scans, PET-avid tumor size of 1 to 5 cm, tumor location (in the lung or as bony metastases), tumor standardized update value (SUV) thresholds relative to tumor size, PET activity around the tumor, and patient tolerance to estimated treatment time. Diagnostic PET/CT images for candidate patients were converted to simulate expected PET images on the machine to calculate activity concentration (AC) and normalized target signal (NTS). If both AC and NTS were above eligibility thresholds, a PET scan was performed on the X1 machine to further evaluate SCINTIX treatment eligibility.
Results: In the few months leading to the first clinical SCINTIX treatment, simulated SCINTIX treatment planning were performed for six candidate patients among all patients evaluated. Two patients were found ineligible as simulated PET images showed low PET activity for the tumor and another patient was not eligible as the prescription dose did not meet SCINTIX treatment criteria. Three candidate patients received PET scans on the X1 machine. One of the patients was found to be not suitable due to low PET activity in the X1 scan, while another patient did not receive SCINTIX treatment due to target location and plan dose conformity. The remaining patient had a left femur bony lesion with maximum SUV of 9.4 and tumor size of around 2 cm. The SCINTIX treatment plan based on the X1 PET scan was generated with a prescription dose of 10 Gy in one fraction and the target volume was found to have an AC of 5.02 kBq/ml and NTS of 4.5. This patient was treated successfully on the X1 machine with a beam-on time of 19 minutes, as the third patient in the US that received SCINTIX treatments and the first patient that received a single-fraction treatment.
Conclusion: A comprehensive set of screening criteria was used for efficient screening of patients for SCINTIX treatment. Introduction of novel treatment modalities including the SCINTIX technique requires close collaboration among radiation oncologists and medical physicists for successful initiation of a clinical program.