The purpose of this study was to examine the accuracy of AcurosXB and
AAA algorithms near low and high density heterogeneities of different
densities using EBT2 film, MOSFET detector “MOSkin” and Monte Carlo
calculations using BEAMnrc/DOSXYZnrc.
Three different interfaces were used that included a solid water phantom with
2x2x30cm3 rectangular air gap, rectangular steel insert, and a slab of water
embedded between two slabs of lung material. 6MV photon beam with field
size of 10x10cm2 was used for the first two geometries and a 3x3cm2-field
was used for the third. Percentage Depth Doses were measured and
calculated at the beam central axis. Calculation voxel of 0.1x0.1x0.1cm3 was
used by all three algorithms.
For all configurations, AcurosXB and AAA agreed to within ±1.3% with MC
before the inhomogeneity. The PDD measurements using MOSkin and EBT2
in water, apart from 0.2cm layer near heterogeneity, agreed with the MC
within ±2.2%. Within 0.1cm before the water-air interface AcurosXB and
AAA overestimated the dose by 4.7% and 1.6%, respectively. Whereas, in
the 0.1cm beyond the air-water interface, AcurosXB and AAA overestimated
the dose by 2.4% and 16.2% respectively. In the 0.1cm before the water-steel
interface, AcurosXB overestimated the dose by 4.7% and AAA
underestimated the dose by 9.5%; beyond the steel-water interface AcurosXB
and AAA overestimated the dose by 3.6% and 7.7% respectively. For the
lung phantom configuration, AcurosXB and AAA were in agreement with
MC within 2% throughout the phantom.
These results demonstrate improved performance of AcurosXB as compared
to AAA in considered conditions.