Robust Proton Treatment Planning: Physical and Biological Optimization

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Biology

Background:

• Radiation therapy planning involves uncertainties, including interpatient variability and dosimetric inaccuracies.
• These uncertainties, stemming from patient geometry, physics approximations, and biological effectiveness, are typically managed using margins and the planning target volume (PTV) concept.
• While effective in intensity-modulated radiotherapy (IMRT), the PTV concept has significant limitations in intensity-modulated proton therapy (IMPT).

Purpose of the Study:

• To review uncertainties inherent in proton therapy.
• To discuss the limitations of the planning target volume (PTV) concept in intensity-modulated proton therapy (IMPT).
• To explore robust optimization techniques for addressing these uncertainties in IMPT.

Main Methods:

• Summarizing uncertainties in proton therapy.
• Analyzing the limitations of the PTV concept for IMPT.
• Reviewing robust optimization methods developed for IMPT planning.
• Discussing the clinical implementation of robust IMPT planning.

Main Results:

• Identified key sources of uncertainty in radiation therapy, including patient geometry and radiation physics.
• Highlighted fundamental limitations of the PTV concept in IMPT due to its inability to directly incorporate uncertainties.
• Reviewed the development and increasing availability of robust optimization techniques in commercial IMPT planning systems.

Conclusions:

• Robust optimization methods are essential for accurate and safe intensity-modulated proton therapy (IMPT) planning.
• These methods directly address uncertainties, overcoming the limitations of the traditional planning target volume (PTV) concept.
• The clinical adoption of robust IMPT planning is increasing, promising improved treatment outcomes.