Sci-Sat AM: Radiation Dosimetry and Practical Therapy Solutions - 04: On 3D Fabrication of Phantoms and Experimental Verification of Patient Dose Computation Algorithms

• Published in: Medical physics (Lancaster) Vol. 43; no. 8; p. 4959
• Main Authors: Khan, Rao, Zavan, Rodolfo, McGeachy, Philip, Madamesila, Joseph, Villarreal-Barajas, Jose Eduardo
• Format: Journal Article
• Language: English
• Published: United States American Association of Physicists in Medicine 01.08.2016
• Subjects: 3D printing; 60 APPLIED LIFE SCIENCES; ALGORITHMS; COMPUTERIZED SIMULATION; DOSIMETRY; Drug delivery; Field size; FREE ENERGY; MATHEMATICAL SOLUTIONS; MONTE CARLO METHOD; Monte Carlo methods; Multilayers; PHANTOMS; RADIATION DOSES; RADIATION PROTECTION AND DOSIMETRY; SLABS; Tissues; VERIFICATION
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.4961858

Purpose: Transport based dose calculation algorithm Acuros XB (AXB) has been shown to accurately account for heterogeneities mostly through comparisons with Monte Carlo simulations. This study aims at providing additional experimental verification for AXB for flattened and unflattened clinical energies in low density phantoms of the same material. Materials and Methods: Polystyrene slabs were created using a bench-top 3D printer. Six slabs were printed at varying densities from 0.23 g/cm3 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 AXB 11.0.31 for 6MV, 15MV flattened and 6FFF (flattening filter free) energies for field sizes of 2×2 cm2 and 5×5 cm2. The phantoms containing radiochromic EBT3 films were irradiated. Absolute dose profiles and 2D gamma analyses were performed for 96 dose planes. Results: For all single slab, multislab configurations and energies, absolute dose differences between the AXB calculation and film measurements remained <3% for both fields, with slightly poor disagreement in penumbra. The gamma index at 2% / 2mm averaged 98% in all combinations of fields, phantoms and photon energies. Conclusions: 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 low density heterogeneous media. This work provides sufficient experimental ground to support the use of AXB for heterogeneous dose calculation purposes.