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Dose-guided patient positioning in proton radiotherapy using multicriteria-optimization.
Christopher Kurz1, Philipp Süss2, Carolin Arnsmeyer3
1Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377 München, Germany; Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany.
Zeitschrift Fur Medizinische Physik
|November 10, 2018
Summary
Dose-guided patient alignment in proton therapy (PT) optimizes positioning for accurate radiation delivery. This multicriterial optimization approach reduces organ-at-risk dose and improves target coverage, offering an alternative to re-planning.
Area of Science:
- Radiation Oncology
- Medical Physics
- Image-Guided Therapy
Background:
- Accurate patient alignment is crucial for effective proton radiotherapy (PT), typically relying on anatomical landmarks or markers.
- Non-rigid anatomical changes during treatment can compromise the accuracy of traditional alignment methods.
- Adapting patient positioning to the actual delivered dose is essential when anatomical variations occur.
Purpose of the Study:
- To investigate dose-guided patient alignment as a multicriterial optimization (MCO) problem for intensity-modulated and double-scattered PT (IMPT and DSPT).
- To implement and evaluate an automated method for determining optimal patient position based on clinical goals.
- To compare the dosimetric advantages of dose-guided alignment against bony-anatomy-based alignment.
Main Methods:
- Developed and implemented an automated MCO method for dose-guided patient alignment in PT.
- Utilized linear dose interpolation to explore a continuous range of patient shifts.
- Analyzed data from 14 head and neck (H&N) and 8 prostate cancer patients with repeated CT scans.
Main Results:
- Dose interpolation demonstrated high accuracy, with average pass-rates of 90% (H&N) and 99% (prostate) using a 2% dose-difference criterion.
- Automated MCO-based dose-guided positioning significantly reduced dose to serial organs-at-risk (spinal cord, brain stem) in H&N patients.
- Prostate cancer patients showed improved target structure dose coverage with dose-guided alignment.
Conclusions:
- Dose-guided patient alignment is a sufficiently accurate and effective method for improving radiation therapy outcomes.
- This approach offers dosimetric benefits, including reduced organ-at-risk toxicity and enhanced target coverage, compared to traditional alignment.
- Automated dose-guided positioning presents a viable alternative to online re-planning for mitigating anatomical changes during PT.
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