Left hippocampus sparing whole brain radiotherapy (WBRT): A planning study

Autor: Tomas Kazda, Miroslav Vrzal, Tomas Prochazka, Petr Dvoracek, Petr Burkon, Petr Pospisil, Adam Dziacky, Tomas Nikl, Radim Jancalek, Pavel Slampa, Radek Lakomy
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Zdroj: Biomedical Papers, Vol 161, Iss 4, Pp 397-402 (2017)
Druh dokumentu: article
ISSN: 1213-8118
1804-7521
DOI: 10.5507/bp.2017.031
Popis: Aims: Unilateral sparing of the dominant (left) hippocampus during whole brain radiotherapy (WBRT) could mitigate cognitive decline, especially verbal memory, similar to the widely investigated bilateral hippocampus avoidance (HA-WBRT). The aim of this planning study is dosimetrical comparison of HA-WBRT with only left hippocampus sparing (LHA-WBRT) plans. Methods: HA-WBRT plans for 10 patients were prepared in accordance with RTOG 0933 trial and served as baseline for comparisons with several LHA-WBRT plans prepared with an effort: 1) to maintain the same left hippocampus dosimetry ("BEST PTV") and 2) to maintain same dosimetry in planning target volume as in HA-WBRT ("BEST LH"). Results: All HA-WBRT plans met RTOG 0933 protocol criteria with a mean Conformity index 1.09 and mean Homogeneity index (HI) 0.21. Mean right and left hippocampal D100% was 7.8 Gy and 8.5 Gy and mean Dmax 14.0 Gy and 13.8 Gy, respectively. "BEST PTV" plans reduced HI by 31.2% (P=0.005) which is mirrored by lower PTV_D2% (-0.8 Gy, P=0.005) and higher PTV_D98% (+1.3 Gy, P=0.005) as well as decreased optic pathway's Dmax by 1 Gy. In "BEST LH", mean D100% and Dmax for the left hippocampus were significantly reduced by 11.2% (P=0.005) and 10.9% (P=0.005) respectively. Conclusions: LHA-WBRT could improve target coverage and/or further decrease in dose to spared hippocampus. Future clinical trials must confirm whether statistically significant reduction in left hippocampal dose is also clinically significant.
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