RT Journal Article
SR Electronic
A1 Kazda, Tomas
A1 Vrzal, Miroslav
A1 Prochazka, Tomas
A1 Dvoracek, Petr
A1 Burkon, Petr
A1 Pospisil, Petr
A1 Dziacky, Adam
A1 Nikl, Tomas
A1 Jancalek, Radim
A1 Slampa, Pavel
A1 Lakomy, Radek
T1 Left hippocampus sparing whole brain radiotherapy (WBRT): A planning study
JF Biomedical papers
YR 2017
VO 161
IS 4
SP 397
OP 402
DO 10.5507/bp.2017.031
UL https://biomed.papers.upol.cz/artkey/bio-201704-0010.php
AB 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.