Verification of Acuros XB dose algorithm using 3D printed low‐density phantoms for clinical photon beams

Abstract

The transport‐based dose calculation algorithm Acuros XB (AXB) has been shown to accurately account for heterogeneities primarily through comparisons with Monte Carlo simulations. This study aims to provide additional experimental verification of AXB for clinically relevant flattened and unflattened beam energies in low density phantoms of the same material. Polystyrene slabs were created using a bench‐top 3D printer. Six slabs were printed at varying densities from 0.23 to 0.68 g/cm3, corresponding to different density humanoid tissues. The slabs were used to form different single and multilayer geometries. Dose was calculated with Eclipse™ AXB 11.0.31 for 6MV, 15MV flattened and 6FFF (flattening filter free) energies for field sizes of 2 × 2 and 5 × 5 cm2. EBT3 film was inserted into the phantoms, which were irradiated. Absolute dose profiles and 2D Gamma analyses were performed for 96 dose planes. For all single slab configurations and energies, absolute dose differences between the AXB calculation and film measurements remained <3% for both fields in the high‐dose region, however, larger disagreement was seen within the penumbra. For the multilayered phantom, percentage depth dose with AXB was within 5% of discrete film measurements. The Gamma index at 2%/2 mm averaged 98% in all combinations of fields, phantoms and photon energies. The transport‐based dose algorithm AXB is in good agreement with the experimental measurements for small field sizes using 6MV, 6FFF and 15MV beams adjacent to various low‐density heterogeneous media. This work provides preliminary experimental grounds to support the use of AXB for heterogeneous dose calculation purposes.

Characterization of an advanced cone beam CT (CBCT) reconstruction algorithm used for dose calculation on Varian Halcyon linear accelerators

“…The first part of the study aimed to establish a CT-PD curve for each tube voltage. The reason why CT-PD curves rather than CT-ED curves were established was because the calculation algorithm used in this study was the AcurosXB algorithm Version 16.1 (Varian Medical Systems, Palo Alto, CA, USA), which explicitly models physical interactions with matters using the mass density and material type for each voxel of the CT dataset [15][16][17][18]. To acquire data for the CT-PD curve, the CIRS CT-ED phantom was placed in the centre of the bore and scanned with the H&N (100 kV), the Pelvis (125 kV), and the Pelvis Large (140 kV) protocols at the maximum FOV and scan range.…”

Dosimetric Evaluation of Commercially Available Flat vs. Self-Produced 3D-Conformal Silicone Boluses for the Head and Neck Region

“…In radiotherapy, the 3D printing fused deposition modeling (FDM) technique introduced by Crump (1) has been used in a variety of ways including the creation of individualized phantoms, brachytherapy applicators, or intraoral stents (2)(3)(4). The fabrication of individualized boluses via 3D printing represents another application of this technique.…”

Individual 3D-printed fixation masks for radiotherapy: first clinical experiences

“…While 3D-printing is implemented in many industrial branches for the creation of cost-effective production of individual 3D-objects [ 1 ], even in the field of medical applications [ 18 ], it is still used only scarcely in radiation oncology. The most common applications are the creation of custom beam range modulation devices [ 4 , 13 ], devices for dosimetry [ 7 , 22 ], or brachytherapy applications [ 5 , 14 ]. With the huge potential of 3D-printing, it may be possible to overcome some of the abovementioned disadvantages of the currently used fixation systems.…”