TITLE:
Dose Reduction to the Scalp with Hippocampal Sparing Is Achievable with Intensity Modulated Radiotherapy
AUTHORS:
Matthew Witek, Yelena Vahknenko, Joshua Siglin, Amy Harrison, Ying Xiao, Haison Lui, David Andrews, Wenyin Shi
KEYWORDS:
Hippocampal, Scalp Sparing WBRT, IMRT
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.3 No.3,
August
19,
2014
ABSTRACT: We
evaluated the feasibility of combined hippocampal- and scalp-sparing intensity-modulated
radiotherapy (IMRT)
plans. This study included 7 patients who received conventional palliative whole
brain radiation treatment (WBRT) for brain metastasis. The brain, hippocampus, and
scalp were contoured and replanned with intensity modulated radiation therapy. The
prescription dose was 30 Gray (Gy) in 10 fractions with hippocampus and normal structure
constraints per the Radiation Therapy
Oncology Group (RTOG) 0933 protocol. Further planning was done to minimize the scalp
dose while maintaining the dose constraints for the hippocampus. Dose volume histograms
were obtained from conventional opposed lateral fields, IMRT and compared. Planning target volume (PTV) coverage for
all plans fell within the RTOG 0933 critical structure acceptable variation category. When compared to traditional opposed
lateral fields, the IMRT plan with combined hippocampal- and scalp-sparing constraints
was able to significantly reduce the max and mean scalp dose as well as the percentage
of scalp receiving 10 and 20 Gy by 46% and 35%, respectively, while maintaining
acceptable RTOG 0933 hippocampal dose variations. We conclude that acceptable PTV coverage and sparing of the scalp and
hippocampus can be accomplished using a 9-field non-coplanar IMRT plan. Prospective
study is warranted to understand the impact on radiation-induced alopecia.