Measuring Differences in Y90 Delivery Techniques: A Potential Tool for Physician Training, Optimization of Technique, and Confirmation of Dose Delivery

Introduction: Two devices are currently approved for Y90 radioembolization: SIR-Spheres and TheraSpheres. Each have different characteristics with SIR-Spheres being made of resin, ranging in size from 20-60 microns, and having a per-sphere activity of approximately 50 Bq. TheraSpheres beads are made of glass with a size range of 20-30 microns and activities of 2,500 Bq. Each of these spheres require similar but unique manual delivery techniques to properly deliver the radioactive beads to the tumor site. This study examines the feasibility of using modular detectors to measure time activity curves (TACs) related to the Y90 dose infusion and provide visual feedback that can be used to optimize delivery techniques for experienced physicians and provide robust training for radiology residents. This study also uses TACs derived from this system to provide near real-time feedback regarding whether or not the full dose was delivered successfully to the patient. Complete dose delivery is often a concern with Y90 radioembolization procedures as issues can arise, such as stasis, that interfere with the full dose infusion. Materials and Methods: For each radioembolization device, a modular detector (Lucerno Dynamics, LLC) was placed at a location near the primary dose vial as well as near the dose delivery catheter. The detector near the dose vial monitored for baseline activity levels of the total dose to be administered and to determine if the total dose was completely delivered. The detector near the catheter line provided time activity curves (TACs) of the actual dose delivered through the catheter allowing for post-therapy analysis of the technique used by a physician for a given patient and radioembolization device. Results: Time activity curves show the differences between the delivery methods used for each of the radioembolization devices. The characteristic delivery techniques of each is clearly observed. Theraspheres cases readily showed the required three flushes of 60 ml of saline resulting in a TAC with three boluses of decreasing activity with each saline flush. The classic pulsed or puffed injections of SIR-Spheres is seen with multiple puffs observed during the infusion each with decreasing activity. The baseline curves on the attached images show that over the course of the infusion, the primary vial reading drops to zero indicating the dose vial has been completely evacuated.

Conclusions: Analysis of time activity curves from both detectors indicate that use of these detectors can provide specific information about a particular radioactive sphere infusion procedure. Data can be used to optimize techniques for a given Y90 therapy device or used to train radiology residents on proper technique. This method can also provide near real-time confirmation of a successful complete delivery of the desired patient dose which may also maximize therapy efficacy and improve patient outcomes.

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