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Simulating respiratory liver motion: Development and evaluation of a deformable phantom for radiotherapy testing
Xipu Jin1, Liting Shi2, Wenbin Wu1
1School of Biomedical Engineering (Suzhou), Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230026, China; Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China.
Summary
A new dynamic liver phantom accurately simulates respiratory motion and deformation. This tool is crucial for validating adaptive radiotherapy techniques and improving tumor targeting accuracy in liver cancer treatment.
Area of Science:
- Medical physics
- Radiotherapy technology
- Biomechanical engineering
Background:
- Respiratory motion during liver radiotherapy causes targeting inaccuracies, potentially leading to underdosing tumors and overdosing healthy liver tissue.
- Adaptive radiotherapy (ART) aims to mitigate these errors, but requires validation with realistic phantoms.
- Developing physiologically accurate phantoms is essential for testing and refining ART algorithms and clinical systems.
Purpose of the Study:
- To develop a dynamic liver phantom capable of simulating respiratory-induced liver motion and deformation.
- To create a platform for rigorously testing adaptive radiotherapy algorithms and clinical radiotherapy systems.
- To enhance the geometric accuracy of tumor targeting in liver radiotherapy.
Main Methods:
- Digital models of liver anatomy (parenchyma, vessels, tumors) were created from patient imaging data.
- Anatomical components were 3D-printed using materials with distinct CT values for contrast and assembled with fiducial markers.
- The model was embedded in a sponge matrix, enclosed in a resin shell, and subjected to programmable motor-driven respiratory motion; biomechanical fidelity was assessed via elastic modulus measurements.
Main Results:
- The phantom demonstrated realistic superior-inferior (5.57 mm), anterior-posterior (1.78 mm), and left-right (0.5 mm) deformation at 30 mm motor displacement.
- Measured elastic modulus values (22.70 kPa small strain, 119.42 kPa large strain) closely approximated those of real liver tissue (34.31 kPa small strain, 171.47 kPa large strain).
Conclusions:
- The developed dynamic liver phantom effectively replicates the complexities of respiratory liver motion and deformation.
- This phantom provides a valuable and validated platform for improving the geometric accuracy of adaptive radiotherapy.
- The phantom facilitates the advancement of radiotherapy techniques for liver cancer, ensuring better treatment outcomes.
