Monte Carlo dose calculation in presence of low-density media: Application to lung SBRT treated during DIBH

Dosimetric Impact of Acuros XB Dose-to-Water and Dose-to-Medium Reporting Modes on Lung Stereotactic Body Radiation Therapy and Its Dependency on Structure Composition

“…For these field sizes and a 6-MV photon beam, differences in lateral electron scattering between AAA and AXB is a minor effect that might only affect the periphery of the PTV. 6 , 10 , 14 , 18 , 38 Concerning the depth dose curves, AAA underestimates the dose in the lung surrounding the GTV, but overestimates secondary build-up in the lung-GTV interface, leading to a higher dose in the GTV region. 6 , 10 , 13 , 18 , 38 As our PTVs contained 66.7% lung tissue on average, the first phenomenon outweighed the second, and the AXB-calculated D mean and D 50 were higher than the AAA values.…”

“… 6 , 10 , 14 , 18 , 38 Concerning the depth dose curves, AAA underestimates the dose in the lung surrounding the GTV, but overestimates secondary build-up in the lung-GTV interface, leading to a higher dose in the GTV region. 6 , 10 , 13 , 18 , 38 As our PTVs contained 66.7% lung tissue on average, the first phenomenon outweighed the second, and the AXB-calculated D mean and D 50 were higher than the AAA values. Of the other studies using AXB v11 or later, some reported findings similar to ours with regard to these parameters, 18 , 19 , 20 others found no differences, 22 , 24 and 1 found an underestimation of AXB-predicted D mean of approximately 1%.…”

“…Under these challenging dose calculation conditions, the Acuros XB (AXB) algorithm 4 -a grid-based linear Boltzmann transport equation solver implemented in the Eclipse treatment planning system (TPS)achieves accuracy rates comparable to Monte Carlo (MC) simulation, which is considered the most accurate dose calculation method in radiotherapy 5 , and superior to the convolution/superposition algorithms still used in routine clinical practice. Numerous studies have compared AXB with measurements, MC, and convolution/superposition algorithms in slab and anthropomorphic phantoms, for representative lung SBRT planning setups [6][7][8][9][10][11][12][13][14] . ICRU report 91 recommends MC or AXB for accurate dose calculation in heterogeneous tissue 3 .…”

“…Numerous studies have compared AXB with measurements, MC, and convolution/superposition algorithms in slab and anthropomorphic phantoms, for representative lung SBRT planning setups. 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 International Commission on Radiation Units and Measurements (ICRU) report 91 recommends MC or AXB for accurate dose calculation in heterogeneous tissue. 3 …”

1st European Congress of Medical Physics September 1–4, 2016; Medical Physics innovation and vision within Europe and beyond

“…Beilla S. et al [13] propose the use of a MC model to assess the quality of dose computation in the context of Stereotactic Body Radiation Therapy (SBRT) during Deep Inspiration Breath Hold (DIBH). A model of the head of a specific LINAC was implemented.…”