Tissue dose estimation after extravasation of ¹⁷⁷Lu-DOTATATE

Area of Science:

• Nuclear Medicine
• Radiopharmaceutical Therapy
• Radiation Dosimetry

Background:

• Extravasation of radiopharmaceuticals can cause severe tissue damage.
• Accurate dose estimation is critical for managing extravasation events.
• Limited data exists on dose estimation following radiopharmaceutical extravasation.

Purpose of the Study:

• To present a methodology for estimating radiation dose distribution after Lutathera® extravasation.
• To assess the absorbed doses in different volumes of the extravasated area.
• To evaluate the clinical implications of the estimated doses.

Main Methods:

• Utilized a local quantification procedure adapted for renal dosimetry.
• Employed whole-body planar and SPECT/CT acquisitions to determine extravasation volume and activity over time.
• Calculated cumulated activities and absorbed doses using the MIRD formalism.

Main Results:

• Estimated extravasation volumes ranged from 180 mL to 1000 mL.
• Absorbed doses varied from 2.3 Gy to 6.8 Gy across the defined volumes.
• Effective local half-life of activity was determined to be 2.3 hours, indicating rapid lymphatic drainage.

Conclusions:

• The developed method enabled rapid local dose estimation following extravasation.
• Estimated doses were below thresholds for severe tissue damage, precluding surgical intervention.
• The patient experienced no clinical consequences from the extravasation event.