SENTRI: Single-particle Energy Transducer for Radionuclide Injections for Personalized Targeted Radionuclide Cancer Therapy

Introduction: Targeted radionuclide therapy (TRT), whereby a tumor-targeted molecule is linked to a therapeutic beta- or alpha-emitting radioactive nuclide, is a promising treatment modality for patients with metastatic Cancer, delivering radiation systemically. However, patients still progress due to suboptimal dosing, driven by the large patient to patient variability. Therefore, the ability to continuously monitor the real-time dose deposition in tumors and organs at risk (OARs) provides an additional dimension of information during clinical trials that can enable insights into better strategies to personalize TRT.

Methods: Here, we present a single beta-particle sensitive dosimeter consisting of a 0.27 mm³ monolithic silicon chiplet, directly implanted into the tumor. To maximize the sensitivity and have enough detection area, minimum size diodes (1 μm²) are arrayed in 64 × 64. Signal amplifiers, buffers, and on chip memories are all integrated in the chip. For verification, PC3-PIP (PSMA+) and PC3-flu (PSMA-) cell lines are injected into the left and right flanks of the mice, respectively. The devices are inserted into each tumor, measure activities at 5 different time points (0-2 hour, 7-9 hour, 12-14 hour, 24-26 hour, and 48-50 hour) post ¹⁷⁷Lu-PSMA-617 injections. SPECT/CT scans are used to verify measured data.

Result: With a wide detection range from 0.013 to 8.95 MBq/mL, the system is capable of detecting high tumor uptake, as well as low doses delivered to OARs in real time. The measurement data is highly proportional (R² > 0.99) to the ¹⁷⁷Lu-PSMA-617 activity. The in vivo measurement data agrees well with the SPECT/CT results within acceptable errors (±1.5 %ID/mL).

Conclusion: Given the recent advances in clinical use of TRT in prostate Cancer, the proposed system is verified in a prostate Cancer mouse model using ¹⁷⁷Lu-PSMA-617.