Dose-painting intensity-modulated proton therapy for intermediate- and high-risk meningioma

作者：Madani Indira^*; Lomax Antony J; Albertini Francesca; Trnkova Petra; Weber Damien C

来源：Radiation Oncology, 2015, 10(1): 72.

DOI：10.1186/s13014-015-0384-x

• Intensity-modulated proton beam-therapy
• Dose painting
• PET
• Simultaneous integrated boost
• Meningioma

Background: Newly diagnosed WHO grade II-III or any WHO grade recurrent meningioma exhibit an aggressive behavior and thus are considered as high- or intermediate risk tumors. Given the unsatisfactory rates of disease control and survival after primary or adjuvant radiation therapy, optimization of treatment strategies is needed. We investigated the potential of dose-painting intensity-modulated proton beam-therapy (IMPT) for intermediate- and high-risk meningioma.
Material and methods: Imaging data from five patients undergoing proton beam-therapy were used. The dose-painting target was defined using [68]Ga-[1,4,7,10-tetraazacyclododecane tetraacetic acid]- d-Phe(1), Tyr(3)-octreotate ([68]Ga-DOTATATE)-positron emission tomography (PET) in target delineation. IMPT and photon intensity-modulated radiation therapy (IMRT) treatment plans were generated for each patient using an in-house developed treatment planning system (TPS) supporting spot-scanning technology and a commercial TPS, respectively. Doses of 66 Gy (2.2 Gy/fraction) and 54 Gy (1.8 Gy/fraction) were prescribed to the PET-based planning target volume (PTVPET) and the union of PET- and anatomical imaging-based PTV, respectively, in 30 fractions, using simultaneous integrated boost.
Results: Dose coverage of the PTVs(PFT) was equally good or slightly better in IMPT plans: dose inhomogeneity was 10 +/- 3% in the IMPT plans vs. 13 +/- 1% in the IMRT plans (p = 0.33). The brain D-mean and brainstem D-50 were small in the IMPT plans: 26.5 +/- 1.5 Gy(RBE) and 0.002 +/- 0.0 Gy(RBE), respectively, vs. 29.5 +/- 1.5 Gy (p = 0.001) and 7.5 +/- 11.1 Gy (p = 0.02) for the IMRT plans, respectively. The doses delivered to the optic structures were also decreased with IMPT.
Conclusions: Dose-painting IMPT is technically feasible using currently available planning tools and resulted in dose conformity of the dose-painted target comparable to IMRT with a significant reduction of radiation dose delivered to the brain, brainstem and optic apparatus. Dose escalation with IMPT may improve tumor control and decrease radiation-induced toxicity.

• 出版日期2015-3-30