Kazda Tomas, Vrzal Miroslav, Prochazka Tomas, Dvoracek Petr, Burkon Petr, Pospisil Petr, Dziacky Adam, Nikl Tomas, Jancalek Radim, Slampa Pavel, Lakomy Radek
Department of Radiation Oncology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic.
Department of Radiation Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic.
Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2017 Dec;161(4):397-402. doi: 10.5507/bp.2017.031. Epub 2017 Jul 20.
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.
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").
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.
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.
在全脑放疗（WBRT）期间单侧保留优势（左侧）海马体可减轻认知衰退，尤其是言语记忆衰退，这与广泛研究的双侧海马体避让（HA-WBRT）相似。本计划研究的目的是对HA-WBRT与仅保留左侧海马体（LHA-WBRT）计划进行剂量学比较。
根据RTOG 0933试验为10例患者制定HA-WBRT计划，并作为与几个精心制定的LHA-WBRT计划进行比较的基线：1）维持相同的左侧海马体剂量学（“最佳计划靶体积”），以及2）在计划靶体积中维持与HA-WBRT相同的剂量学（“最佳左侧海马体”）。
所有HA-WBRT计划均符合RTOG 0933方案标准，平均适形指数为1.09，平均均匀性指数（HI）为0.21。右侧和左侧海马体的平均D100%分别为7.8 Gy和8.5 Gy，平均Dmax分别为14.0 Gy和13.8 Gy。“最佳计划靶体积”计划使HI降低了31.2%（P = 0.005），这反映在较低的计划靶体积_D2%（-0.8 Gy，P = 0.005）和较高的计划靶体积_D98%（+1.3 Gy，P = 0.
