Experimental validation of Fastcat kV and MV cone beam CT (CBCT) simulator

Purpose: To experimentally validate the Fastcat cone beam CT (CBCT) simulator against kV and MV CBCT images acquired with a Varian Truebeam linac. Methods: of Catphan 504 phantom were using 100 kVp on-board imager (OBI) 6 treatment electronic portal imaging device (EPID), respectively. The simulation was performed detailed models x-ray source, bowtie filter, high resolution voxelized virtual phantom, anti-scatter grid, CsI scintillating detector. Likewise, an simulated for energy spectrum, flattening GOS Experimental compared respect to HU values, contrast noise ratio (CNR),and dose linearity. Detector modulation transfer function (MTF) two detectors also validated. Fastcat's calculations MC Topas. Results: For simulations, respectively: Contrast agreed within 14 9 HUs detector MTF 4.2% 2.5%. CNR had root mean squared error (RMSE) 2.6% 1.4%. Dose 2.4% 1.6% values. took 71 72 seconds simulate in 887 493 projections, Conclusions: We present multi experimental validation fast accurate commercial is open source all found this work can be downloaded from https://github.com/jerichooconnell/fastcat.git