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Sparing the Hippocampus in Prophylactic Cranial Irradiation Using Three Different Linear Accelerators: A Comparative
Georgios Giakoumettis1, Areti Gkantaifi2,3, Dimitrios Giakoumettis4
1Medical Physics and Digital Innovation Laboratory, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, GRC.
Protecting the hippocampus during prophylactic cranial irradiation (PCI) for small cell lung cancer (SCLC) is crucial. The Elekta Infinity linear accelerator, with its large field opening and thin multileaf collimator, demonstrated the best overall performance for target coverage, hippocampus sparing, and plan deliverability.
Area of Science:
- Radiation Oncology
- Medical Physics
- Oncology
Background:
- The hippocampus is an organ at risk in brain radiotherapy, and its protection is vital for patient quality of life.
- Prophylactic cranial irradiation (PCI) is a standard treatment for small cell lung cancer (SCLC) to improve survival.
Purpose of the Study:
- To identify parameters contributing to successful PCI with simultaneous hippocampus protection.
- To compare the performance of three different linear accelerators (LINACs) in achieving these goals.
Main Methods:
- Treatment plans were generated for 45 SCLC patients using three LINACs (Elekta Infinity, Synergy, and Axesse) with varying field sizes and multileaf collimator (MLC) characteristics.
- Plans were evaluated based on target coverage, maximum dose, conformity index (CI), plan modulation (MOD), and patient-specific quality assurance (QA) pass rates, adhering to Radiation Therapy Oncology Group 0933 dose constraints for the hippocampus.
Main Results:
- The Elekta Infinity LINAC achieved the highest mean target coverage (97.3%).
- The Axesse LINAC showed the highest conformity index (0.93), while Synergy had the lowest plan modulation (2.88).
- Patient-specific QA success rates varied, with Infinity having 100% success, Synergy 97.8%, and Axesse 37.8%.
Conclusions:
- The Elekta Infinity LINAC, featuring the largest field opening and thinnest MLC leaves, provided the most favorable combination of target coverage, hippocampus sparing, and plan deliverability.
- LINAC characteristics significantly influence the ability to achieve effective PCI while protecting the hippocampus.
