Conventional Hepatic Volumetry May Lead to Inaccurate Segmental Yttrium-90 Radiation Dosimetry

Area of Science:

• Interventional Radiology
• Medical Imaging
• Nuclear Medicine

Background:

• Radioembolization with Yttrium-90 (Y90) is a common treatment for liver tumors.
• Accurate dosimetry is crucial for effective Y90 radioembolization.
• Current methods for determining treatment volumes, such as planning CT/MRI, may have limitations.

Purpose of the Study:

• To compare treatment zone volumes derived from cone beam CT (CBCT) versus planning CT/MRI in Y90 radioembolization.
• To assess the impact of these volume differences on radiation dosimetry.
• To identify factors influencing discrepancies in volume measurements.

Main Methods:

• Retrospective analysis of Y90 radioembolization cases with intra-procedural CBCT.
• Semi-automated contouring of segmental and lobar treatment volumes using Couinaud anatomy (CT/MRI) or tumor enhancement (CBCT).
• Comparison of volumes using Wilcoxon signed-rank test and modeling of delivered dose with MIRD calculations.

Main Results:

• CBCT-derived segmental volumes were significantly smaller than those from Couinaud anatomy (243 mL vs. 281 mL).
• Couinaud anatomy overestimated segmental volumes in 28 cases and underestimated in 12 cases, leading to significant dose discrepancies.
• Factors like microcatheter position and variant arterial anatomy influenced volumetric differences.

Conclusions:

• Cone beam CT (CBCT)-based volumetry provides a more accurate assessment of treatment zones for Y90 radioembolization.
• This enhanced accuracy can enable more personalized and effective dosimetry.
• CBCT volumetry may improve treatment planning and outcomes in Y90 radioembolization.