Radiation Oncology (Jan 2018)

HyperArc VMAT planning for single and multiple brain metastases stereotactic radiosurgery: a new treatment planning approach

  • Shingo Ohira,
  • Yoshihiro Ueda,
  • Yuichi Akino,
  • Misaki Hashimoto,
  • Akira Masaoka,
  • Takero Hirata,
  • Masayoshi Miyazaki,
  • Masahiko Koizumi,
  • Teruki Teshima

DOI
https://doi.org/10.1186/s13014-017-0948-z
Journal volume & issue
Vol. 13, no. 1
pp. 1 – 9

Abstract

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Abstract Purpose The HyperArc VMAT (HA-VMAT) planning approach was newly developed to fulfill the demands of dose delivery for brain metastases stereotactic radiosurgery. We compared the dosimetric parameters of the HA-VMAT plan with those of the conventional VMAT (C-VMAT). Material and methods For 23 patients (1–4 brain metastases), C-VMAT and HA-VMAT plans with a prescription dose of 20–24 Gy were retrospectively generated, and dosimetric parameters for PTV (homogeneity index, HI; conformity index, CI; gradient index, GI) and brain tissue (V2Gy-V16Gy) were evaluated. Subsequently, the physical characteristics (modulation complexity score for VMAT, MCSV; Monitor unit, MU) of both treatment approaches were compared. Results HA-VMAT provided higher HI (1.41 ± 0.07 vs. 1.24 ± 0.07, p < 0.01), CI (0.93 ± 0.02 vs. 0.90 ± 0.05, p = 0.01) and lower GI (3.06 ± 0.42 vs. 3.91 ± 0.55, p < 0.01) values. Moderate-to-low dose spreads (V4Gy-V16Gy) were significantly reduced (p < 0.01) in the HA-VMAT plan over that of C-VMAT. HA-VMAT plans resulted in more complex MLC patterns (lower MCSV, p < 0.01) and higher MU (p < 0.01). Conclusions HA-VMAT plans provided significantly higher conformity and rapid dose falloff with respect to the C-VMAT plans.

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