The β^- radio-guided surgery: Method to estimate the minimum injectable activity from ex-vivo test

Area of Science:

• Nuclear Medicine
• Surgical Oncology
• Radiopharmaceutical Therapy

Background:

• Radio-guided surgery (RGS) with beta decays is an emerging technique for enhanced tumor detection.
• Its advantage lies in identifying small tumor samples (≤0.1 ml) using low radiopharmaceutical activity.
• This study quantifies this capability in meningioma patients.

Purpose of the Study:

• To experimentally quantify the detection limit of radio-guided surgery with beta decays for small tumor samples.
• To assess the feasibility and radiation safety of this technique in meningioma surgery.
• To determine the minimum effective radiotracer activity for radio-guided surgery.

Main Methods:

• Patients were selected based on Standard Uptake Value (SUV) and tumor-to-non-tumor activity ratio (TNR) from 68Ga-DOTATOC PET scans.
• 26 surgical samples from meningioma patients were analyzed using a beta-minus probe after injecting 90Y-DOTATOC.
• Radioactivity was estimated based on PET SUV, and correlation with measured counts was studied. Personnel radiation doses were also evaluated.

Main Results:

• Tumor residuals as small as 0.1 ml were detectable even with low radiotracer injection (1.4 MBq/kg).
• A negligible radiation dose was confirmed for medical personnel.
• A correlation exceeding 80% was observed between expected and measured radioactivity in lesion samples.

Conclusions:

• Radio-guided surgery with beta decays is a feasible and safe technique, particularly when using the minimum required radiotracer activity.
• The technique offers low radiation exposure for both patients and medical staff.
• This study establishes the minimum injectable radiotracer activity for 90Y-based radio-guided surgery, correlating PET-derived SUV and TNR with probe measurements.