Use of genetic algorithm for PTV optimization in single isocenter multiple metastases radiosurgery treatments with
José Alejandro Rojas-López1, Rogelio Manuel Díaz Moreno1, Carlos Daniel Venencia1
1Instituto Zunino, Obispo Oro 423, 5000 Córdoba, Argentina.
Summary
A genetic algorithm optimized planning target volume (PTV) margins for stereotactic radiosurgery by determining maximum target displacement. This optimization improved dosimetric parameters and reduced healthy brain radiation exposure.
Area of Science:
- Radiotherapy and Radiation Oncology
- Medical Physics
- Computational Biology
Background:
- Accurate planning target volume (PTV) margins are crucial for effective and safe stereotactic radiosurgery (SRS), especially for multiple metastases.
- Optimizing PTV margins can minimize radiation dose to healthy tissues while ensuring adequate coverage of the gross tumor volume (GTV).
- Single isocenter techniques require precise margin calculations to account for potential rotational uncertainties.
Purpose of the Study:
- To optimize PTV margins for single isocenter multiple metastases SRS using a genetic algorithm (GA).
- To determine the maximum effective displacement of each GTV considering rotational uncertainties (roll, pitch, yaw).
- To evaluate the dosimetric impact of GA-optimized PTV margins compared to standard criteria.
Main Methods:
- Ten SRS plans for multiple brain metastases were created using Elements Multiple Mets™ software.
- A GA was employed to optimize the PTV margin based on GTV-isocenter distance, target dimensions, and rotational displacement.
- Optimized plans were recalculated, and dosimetric parameters including Dmean, D99, Paddick conformity index (PCI), gradient index (GI), and healthy brain V12/V10 were analyzed.
Main Results:
- For targets within 50 mm of the isocenter, the maximum GA-calculated displacement was 2.5 mm.
- Statistically significant improvements were observed in Dmean, D99, PCI, and GI with optimized PTV margins.
- A significant reduction in healthy brain V12 and V10 was achieved using the optimized margins.
Conclusions:
- The GA effectively determines optimized PTV margins based on maximum displacement for single isocenter SRS.
- Optimized PTV margins lead to improved dosimetric parameters and reduced radiation exposure to surrounding healthy brain tissue.
- The study highlights the benefit of GA-driven margin optimization in SRS for complex treatment scenarios.
