Program Information

Dosimetric Comparisons of Different Hypofractionated Stereotactic Radiotherapy Techniques in Treating Large Intracranial Tumors

H Cao¹*, Z Xiao^2,3 , X Li⁴ , Z Dai⁵ , X Wang² , A Khan² , N Yue² , Y Bai¹ , K Nie² , (1) Radiation Oncology Center of Renji Hospital, Shanghai, ,(2) Rutgers-Cancer Institute of New Jersey, Rutgers-Robert Wood Johnson Medical, New Brunswick, NJ, (3) Proton Therapy Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, (4) William Beaumont Hospital, Royal Oak, MI, (5) Changhai Hospital, Shanghai, Shanghai,

Presentations

SU-K-FS1-10 (Sunday, July 30, 2017) 4:00 PM - 6:00 PM Room: Four Seasons 1

Purpose: To compare the dosimetric quality of hypofractionated stereotactic radiosurgery in treating sizeable brain tumors across various treatment platforms as GammaKnife (GK) ICON®, CyberKnife (CK) G4, volumetric modulated arc therapy (VMAT) on Varian TrueBeam STx®, double scattering proton therapy (DSPT) on Mevion S250 and intensity modulated proton therapy (IMPT) on Varian ProBeam®.

Methods: Ten patients with large brain tumors (>3cm in diameter, volume range [8.6-41.7cc]) were included. The prescription dose was 20-30 Gy in 5 fractions. Six treatment plans were performed for each patient using the same constrains: (1) GK plan using GammaPlan V11, (2) CK plan using Multiplan V4.5, (3) coplanar arc (VMAT-C) on TrueBeam STx, (4) non-coplanar arc (VMAT-NC), (5) double scattering (DSPT) and (6) scanning beam proton treatment (IMPT). The target coverage, conformity index (CI), gradient index (GI), homogeneity index (HI), mean and max point dose of organ at risks (OARs), and normal brain V2, V5, V10, V15 were compared across all platforms.

Results: Among six treatment techniques, GK consistently produced sharper dose fall-off despite greater central target dose. The mean GI was 2.7, 2.9, 3.0, 3.4, 3.6 and 3.7 for GK, CK, VMAT-C, VMAT-NC, DSPT and IMPT, respectively. Low dose delivery to the brain as V5 and V10 were smaller using non-coplanar arc when compared to coplanar arc. The mean HI was the best with DSPT technique of 0.02 and GK was the highest of 0.7. The volume of normal brain that received 2Gy was the lowest for both proton techniques, with 666, 979, 604, 696, 232 and 329cm³ for GK, CK, VMAT-C, VMAT-NC, DSPT and IMPT.

Conclusion: Our study suggests the effective utilization of fractionated delivery of stereotactic radiotherapy in treating sizeable brain tumors. It provides an insightful understanding of dosimetric quality across the most advanced stereotactic radiotherapy platforms from both photon and proton treatment.

Funding Support, Disclosures, and Conflict of Interest: Cancer Center Support Grant P30CA072720, RBHS Precision Medicine Pilot Grant

Contact Email: