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MO‐FG‐303‐03: Demonstration of Universal Knowledge‐Based 3D Dose Prediction
Author(s) -
Shiraishi S,
Moore K L
Publication year - 2015
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4925416
Subject(s) - voxel , nuclear medicine , radiosurgery , dosimetry , standard deviation , radiation treatment planning , isocenter , prostate , range (aeronautics) , medicine , mathematics , computer science , radiation therapy , artificial intelligence , statistics , radiology , imaging phantom , materials science , cancer , composite material
Purpose: To demonstrate a knowledge‐based 3D dose prediction methodology that can accurately predict achievable radiotherapy distributions. Methods: Using previously treated plans as input, an artificial neural network (ANN) was trained to predict 3D dose distributions based on 14 patient‐specific anatomical parameters including the distance (r) to planning target volume (PTV) boundary, organ‐at‐risk (OAR) boundary distances, and angular position ( θ,φ). 23 prostate and 49 stereotactic radiosurgery (SRS) cases with ≥1 nearby OARs were studied. All were planned with volumetric‐modulated arc therapy (VMAT) to prescription doses of 81Gy for prostate and 12–30Gy for SRS. Site‐specific ANNs were trained using all prostate 23 plans and using a 24 randomly‐selected subset for the SRS model. The remaining 25 SRS plans were used to validate the model. To quantify predictive accuracy, the dose difference between the clinical plan and prediction were calculated on a voxel‐by‐voxel basis δD(r,θ,φ)=Dclin(r,θ,φ)‐Dpred(r, θ,φ). Grouping voxels by boundary distance, the mean <δ Dr>=(1/N)Σ _θ,φ D(r,θ,φ) and inter‐quartile range (IQR) quantified the accuracy of this method for deriving DVH estimations. The standard deviation (σ) of δ D quantified the 3D dose prediction error on a voxel‐by‐voxel basis. Results: The ANNs were highly accurate in predictive ability for both prostate and SRS plans. For prostate, <δDr> ranged from −0.8% to +0.6% (max IQR=3.8%) over r=0–32mm, while 3D dose prediction accuracy averaged from σ=5–8% across the same range. For SRS, from r=0–34mm the training set <δDr> ranged from −3.7% to +1.5% (max IQR=4.4%) while the validation set <δDr> ranged from −2.2% to +5.8% (max IQR=5.3%). 3D dose prediction accuracy averaged σ=2.5% for the training set and σ=4.0% over the same interval. Conclusion: The study demonstrates this technique's ability to predict achievable 3D dose distributions for VMAT SRS and prostate. Future investigations will attempt to separate and quantify modeling error and plan quality variations in the statistical noise. Research funding support from Varian Medical Systems