Exhibit Hall | Forum 6
Purpose: The administration of ⁹⁰Y-microspheres for radioembolization therapy of hepatic malignancies includes planning that involves an angiographic mapping and the injection of permanent ⁹⁰Y-microspheres as the carrier of the radiation to the hepatic arteries. Both are under fluoroscopy-guidance. In practice, we observe that ~4% of the administration procedures deliver >5Gy cumulative Reference Air Kerma (RAK), much higher than the overall incidence rate of ~0.4%. This study is to characterize the radiation dose of fluoroscopically-guided ⁹⁰Y-microspheres administration procedures and identify root causes resulting in a higher incidence rate.
Methods: 346 fluoroscopically-guided ⁹⁰Y-microspheres radioembolization procedures were retrospectively analyzed, including 162 mapping and 184 injection procedures, conducted between 05/2017 and 02/2022. The administered activity, patient body mass index (BMI), and RAK were retrieved. Clinical cases were categorized based on the type of procedures (mapping vs. injection), type of ⁹⁰Y-microspheres (SIR-Spheres vs. TheraSphere), and number of vials (1 vs. ≥2). Radiation doses between different types of procedures, ⁹⁰Y-microspheres, and number of vials as well as their correlation with BMI or administered activity were statistically compared.
Results: RAKs from 14 procedures (~4%) exceeded 5 Gy. Among them, 12 were mapping procedures. The mapping procedures with ≥2-vials showed a much higher incidence rate of 16.7% (5 of 30). RAK of mapping was significantly higher than RAK for injection (2601±1110.7 vs. 1025.0±229.1 mGy, p<0.01), and RAK for mapping with ≥2-vials was significantly higher than 1-vial (3535.3±453.5 vs. 2368.9±1232.9 mGy, p<0.01). There was no significant difference in RAK between procedures using SIR-Spheres or procedures using TheraSphere. No strong correlation was observed between RAK and administered activity or BMI.
Conclusion: Fluoroscopically-guided radioembolization mapping procedures, especially those requiring ≥2-vials likely deliver larger radiation dose (>5Gy) to patients compared to injection procedures. Further investigations are warranted to identify other possible root causes of the higher radiation dose beside the case complexity.