A novel 3D-printed phantom insert for 4D PET/CT imaging and simultaneous integrated boost radiotherapy

Area of Science:

• Medical Physics
• Radiotherapy
• 3D Printing Technology

Background:

• Accurate radiotherapy planning requires realistic phantoms to simulate tumor characteristics.
• Simultaneous Integrated Boost (SIB) involves delivering dose to both gross tumor volume and planning target volume.
• 4D PET/CT imaging is crucial for motion-aware radiotherapy planning.

Purpose of the Study:

• To develop a 3D-printed phantom insert that replicates variable positron emission tomography (PET) tracer uptake in lung tumors.
• To create a matching dosimetric insert for validating SIB phantom studies.
• To assess the phantom's performance through end-to-end testing.

Main Methods:

• Designed and manufactured a cylindrical phantom with a novel 3D-printed insert using ABS-P430 thermoplastic.
• The insert features a porous structure mimicking a 2:1 PET tracer concentration ratio between core and periphery.
• Developed a matching dosimetric insert with holes for ion chambers and cell vials for gated radiotherapy validation.

Main Results:

• Achieved a 2:1 18F-FDG concentration ratio in the 3D-printed insert, matching the design specifications.
• 4D PET/CT scans were successfully acquired, suitable for segmentation and treatment planning.
• Dose measurements in the dosimetric insert agreed with planned doses within 3% (static) and 5% (motion).

Conclusions:

• The 3D-printed phantom insert effectively mimics variable tumor PET tracer uptake.
• The phantom system is suitable for end-to-end quality assurance of SIB gated radiotherapy.
• Demonstrated the feasibility of using these phantoms for advanced radiotherapy applications.