Program Information
Validation of 3D Patient-Specific Quality-Assurance Software (COMPASS) Using AAPM TG-119
S Sharma*, V Subramani , P Kumar , S Bhaskar , S Pathy , S Thulkar , N Gopishankar , S Chander , All India Institute of Medical Sciences, New Delhi, Delhi
Presentations
SU-I-GPD-T-214 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: Aim of study is to evaluate commissioning accuracy of COMPASS, 3D patient-specific quality-assurance software for volumetric modulated arc therapy (VMAT) using AAPM TG-119 protocol.
Methods: VMAT plans were created for downloadable contoured structure set of TG119 cases for energy 6MV using Monaco (5.11) treatment planning system for Versa-HD linear-accelerator. All cases dose prescription and constraints were kept as per TG119. Plans were exported to linear-accelerator and COMPASS via DICOM. Plans were measured with I’matriXX detector (gantry mount) along with COMPASS software. Monaco versus COMPASS computed and COMPASS reconstructed doses were compared using dose volume histogram. Plans were exported to My-QA software for 2D planar analysis using gamma-index (3%/3mm criteria). Point dose measurement were performed with CC01 (0.01cc) ion chamber in high and low dose region.
Results: Monaco versus COMPASS computed percentage variations were as: [i] Prostate: PTV-D95&D5 (-0.12%/1.18%); Rectum: D30&D10 (0.81%/0.42%); Bladder: D30&D10 (-0.02%/0.32%) [ii]Multi-target: Central D99&D10 (-3.9%/2.72%); Superior D99&D10 (1.1%/2.71%); Inferior D99&D10 (1.2%/3.09%) [iii]Head and Neck: PTV-D90,D99&D20 (0.08%/-3.48%/1.86%); Cord-maximum (1.0%); parotid-D50 (1.91%) [iv] C-Shape: PTV-D95&D10 (0.21%/2.01%); Core-D10 (7.78%). Monaco versus COMPASS reconstructed percentage variations were as: [i] Prostate: PTV-D95&D5 (-1.27%/2.05%); Rectum: D30&D10 (-4.99%/-4.20%); Bladder: D30&D10 (-6.97%/8.12%) [ii] Multi-target: Central D99&D10 (1.7%/2.54%); Superior D99&D10 (1.5%/1.71%); Inferior D99&D10 (-0.9%/-8.29%) [iii] Head and Neck: PTV-D90, D99&D20 (1.78%/0.81%/2.42%); Cord-maximum (-3.70%); parotid-D50 (0.96%) [iv] C-Shape: PTV-D95&D10 (-0.44%/2.68%); Core-D10 (2.44%). 2D-Gamma pass rate for Monaco versus COMPASS computed were 98.2%, 98.1%, 96.3%, 97.3% and Monaco versus COMPASS reconstructed were 97.7%, 98.9%, 94.1%, 97.1% for prostate, multi-target, head and neck and C-Shape respectively. Point dose measurement percentage variation with respect to Monaco and COMPASS computed were within 3.0% for high dose region and 5.0% for low dose region.
Conclusion: COMPASS results are in satisfactory agreement with Monaco calculation and machine delivery; therefore can be used for patient-specific 3D pre-treatment quality assurance in clinic.
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