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Updated: May 27, 2026
12:34
Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence
Published on: June 24, 2016
Margins for translational and rotational uncertainties: a probability-based approach
Peter Remeijer1, Coen Rasch, Joos V Lebesque
1Department of Radiotherapy, The Netherlands Cancer Institute/Antoni van Leeuwenhoek Huis, Amsterdam, The Netherlands. prem@nki.nl
Summary
A new Rotational and Translational Confidence Limit (RTCL) method accurately accounts for systematic rotations in treatment planning. This method is less shape-dependent and allows for smaller planning target volumes (PTVs) while ensuring CTV coverage.
Area of Science:
- Medical Physics
- Radiation Oncology
- Image-Guided Therapy
Background:
- Accurate patient positioning is crucial in radiation therapy.
- Systematic rotations and translations can compromise treatment accuracy.
- Existing methods for margin expansion may not adequately account for rotational uncertainties.
Purpose of the Study:
- To develop and evaluate a novel method for defining margins that incorporates systematic rotations and translations.
- To compare the proposed method with existing algorithms for margin expansion.
Main Methods:
- The Rotational and Translational Confidence Limit (RTCL) method was developed by extending the rolling ball algorithm to include rotations.
- The RTCL method was compared against a non-rotational rolling ball algorithm and a convolution method.
- Planning target volumes (PTVs) were generated for various shapes, including clinical cases, and evaluated using Monte Carlo simulations.
Main Results:
- The RTCL method demonstrated superior accuracy in maintaining clinical target volume (CTV) coverage across different shapes compared to existing methods.
- When adjusted for equal CTV-in-PTV probability, the RTCL method resulted in significantly smaller PTV volumes.
- The RTCL method showed an average P(CTVinPTV) of 84% for non-spherical shapes, compared to 57% and 46% for other methods.
Conclusions:
- The RTCL method offers an accurate and robust approach for incorporating systematic rotations into treatment margins.
- This method is less sensitive to the clinical target volume's shape, improving PTV definition.
- The RTCL method enables the creation of smaller, more precise PTVs while maintaining adequate CTV coverage.
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