Fast multifield optimization of the biological effect in ion therapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiobiology

Background:

• Intensity-modulated radiotherapy (IMRT) with ion beams requires sophisticated treatment planning.
• Optimizing for biological effect (relative biological effectiveness times dose) is crucial for effective cancer treatment.
• Current methods may not fully account for all planning constraints or optimize biological outcomes efficiently.

Purpose of the Study:

• To develop and present a novel technique for simultaneous multifield optimization of biological effect in ion beam IMRT.
• To enable complete inverse treatment planning considering both target volume and organs at risk constraints.
• To reduce calculation time and improve treatment plan quality compared to existing methods.

Main Methods:

• Utilized the mixed irradiation formalism of the linear-quadratic model from radiobiology.
• Developed a novel objective function to directly optimize biological effect, not physical dose.
• Integrated the new optimization method into the KonRad inverse treatment planning tool.
• Reduced biological input data requirements, making them independent of the optimization process.

Main Results:

• The new method was successfully integrated into the KonRad treatment planning system.
• Comparisons with TRiP98 showed very good agreement for various treatment scenarios.
• KonRad demonstrated a substantial reduction in calculation time.
• Multifield optimization significantly improved treatment plan quality and sparing of healthy tissues.

Conclusions:

• The presented technique offers a superior approach to ion beam IMRT planning by optimizing biological effect.
• The method enhances treatment efficacy and patient safety through improved target coverage and organ-at-risk sparing.
• The reduced calculation time makes this approach practical for clinical implementation.