Dosimetric comparison of advanced radiotherapy planning techniques for hippocampal sparing whole brain radiotherapy
Öznur Şenkesen1, Emine Burçin Ispir2, Evren Ozan Göksel3
1Acıbadem Mehmet Ali Aydınlar University, Istanbul, Turkey; Department of Radiation Oncology, Acıbadem Ataşehir Hospital, Istanbul, Turkey.
Purpose:
Hippocampal-sparing whole-brain radiotherapy aims to reduce neurocognitive decline in patients receiving cranial irradiation. Advances in radiotherapy planning systems offer improved sparing of organs at risk while maintaining target coverage. This study compared the dosimetric performance of five planning techniques for hippocampal-sparing whole-brain radiotherapy: Radixact with 1cm and 2.5cm field widths, Ethos, HyperArc, and volumetric modulated arctherapy using advanced optimization algorithms.
Materials And Methods:
Eleven patients who underwent whole brain irradiation were included in this retrospective planning study. The prescribed dose was 30Gy in 12 fractions, with hippocampus dose constraints of D98 %≤9Gy and D2 %≤17Gy. Radixact plans were created using the VOLO™ Ultra optimizer with normal tissue objective parameters for dose fall-off control. Ethos plans were generated using an intelligent optimization engine with automated planning. HyperArc employed four non-coplanar arcs with SRS normal tissue objective optimization, while volumetric modulated arctherapy utilized six arcs. Dosimetric parameters, including planning target volume coverage, hippocampal doses, and organs at risk constraints, were analyzed using one-way ANOVA.
Results:
Radixact with 1cm field width achieved the lowest hippocampal doses, whereas HyperArc and volumetric modulated arctherapy provided superior planning target volume coverage. Ethos resulted in the lowest doses to organs at risk, while HyperArc had the shortest treatment duration. Statistically significant differences (P<0.05) were observed across techniques for hippocampal D98 %, D2 %, and sparing of organs at risk.
Conclusion:
Advanced planning techniques offer distinct dosimetric advantages for hippocampal-sparing whole-brain radiotherapy. Radixact with 1cm field width optimally spares the hippocampus, while HyperArc and volumetric modulated arctherapy balance sparing of organs at risk with shorter treatment times. Selection of an optimal planning approach should consider both dosimetric outcomes and clinical workflow efficiency.
