3D-Printed Organ-Realistic Phantoms to Verify Quantitative SPECT/CT Accuracy for 177Lu-PSMA-617 Treatment Planning

Area of Science:

• Medical Imaging and Dosimetry
• Radiopharmaceutical Therapy (RPT)
• 3D Printing Technology

Background:

• Accurate patient-specific dosimetry is crucial for optimizing radiopharmaceutical therapy (RPT).
• Current dosimetry tools lack validation under clinically realistic conditions.
• Need for reliable methods to commission patient-specific RPT radioactivity quantification.

Purpose of the Study:

• To develop a workflow for designing and fabricating patient-derived, organ-realistic RPT phantoms.
• To evaluate the feasibility of these phantoms for commissioning patient-specific RPT radioactivity quantification.
• To support accurate dosimetry for personalized RPT.

Main Methods:

• Utilized patient CT/MR imaging, CAD, and 3D printing to create anthropomorphic kidney and parotid phantoms.
• Phantoms featured realistic organ spacing, orientation, and tissue heterogeneities.
• Injected known 177Lu-PSMA-617 radioactivity into phantoms for SPECT/CT imaging and quantitative analysis.

Main Results:

• Fabricated phantoms cost-effectively (<$250, <84 hours) with geometric accuracy and watertightness.
• Quantitative SPECT imaging underestimated injected radioactivity (mean error: -13.2%).
• Recovery coefficients ranged from 0.82 to 0.93, correlated with phantom geometry.

Conclusions:

• Patient-derived, 3D-printed phantoms are a feasible and cost-effective tool for RPT dosimetry commissioning and QA.
• These phantoms enable comprehensive accuracy evaluation in clinically relevant geometries.
• Widespread use can improve RPT dose response understanding and enable personalized dosing.