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Four-Dimensional CT Analysis Using Sequential 3D-3D Registration
Published on: November 23, 2019
Interfractional reproducibility in pancreatic position based on four-dimensional computed tomography.
Takehiro Shiinoki1, Keiko Shibuya, Mitsuhiro Nakamura
1Department of Nuclear Engineering, Graduate School of Engineering, Kyoto University, Kyoto, Japan.
Summary
Pancreatic tumor motion and interfractional variations are significant. End-exhalation breathing offers higher positional reproducibility for radiation dose delivery compared to end-inhalation.
Area of Science:
- Radiation Oncology
- Medical Imaging
- Anatomical Motion Analysis
Background:
- Pancreatic tumors exhibit motion due to respiration, complicating accurate radiation delivery.
- Four-dimensional computed tomography (4D-CT) is utilized to assess organ motion during the breathing cycle.
- Understanding interfractional positional variation is crucial for optimizing treatment strategies.
Purpose of the Study:
- To quantify the interfractional positional variation of the pancreas using 4D-CT.
- To identify the optimal respiratory phase for radiation dose delivery to manage pancreatic tumor motion.
Main Methods:
- Fifteen pancreatic cancer patients underwent 4D-CT scans during treatment.
- Intrapancreatic bile ducts served as surrogates for pancreatic position.
- Positional data were analyzed at end-inhalation and end-exhalation for respiratory motion and interfractional variation in LR, AP, and SI directions.
Main Results:
- Median respiratory motion ranged from 1.1 mm (LR) to 5.0 mm (SI).
- Interfractional positional variation showed higher standard deviations at end-inhalation versus end-exhalation (LR and SI, p < 0.001).
- End-exhalation demonstrated superior interfractional positional reproducibility.
Conclusions:
- Respiratory motion and interfractional positional variations of the pancreas are clinically relevant.
- End-exhalation is a more reproducible phase for radiation delivery in pancreatic cancer patients.
- These findings support tailored treatment planning to account for pancreatic motion.
