A comparison of two dose calculation algorithms—anisotropic analytical algorithm and Acuros XB—for radiation therapy planning of canine intranasal tumors

Abstract

Although anisotropic analytical algorithm (AAA) and Acuros XB (AXB) are both radiation dose calculation algorithms that take into account the heterogeneity within the radiation field, Acuros XB is inherently more accurate. The purpose of this retrospective method comparison study was to compare them and evaluate the dose discrepancy within the planning target volume (PTV). Radiation therapy (RT) plans of 11 dogs with intranasal tumors treated by radiation therapy at the University of Georgia were evaluated. All dogs were planned for intensity-modulated radiation therapy using nine coplanar X-ray beams that were equally spaced, then dose calculated with anisotropic analytical algorithm. The same plan with the same monitor units was then recalculated using Acuros XB for comparisons. Each dog's planning target volume was separated into air, bone, and tissue and evaluated. The mean dose to the planning target volume estimated by Acuros XB was 1.3% lower. It was 1.4% higher for air, 3.7% lower for bone, and 0.9% lower for tissue. The volume of planning target volume covered by the prescribed dose decreased by 21% when Acuros XB was used due to increased dose heterogeneity within the planning target volume. Anisotropic analytical algorithm relatively underestimates the dose heterogeneity and relatively overestimates the dose to the bone and tissue within the planning target volume for the radiation therapy planning of canine intranasal tumors. This can be clinically significant especially if the tumor cells are present within the bone, because it may result in relative underdosing of the tumor.

Comparative study of the collapsed cone convolution and Monte Carlo algorithms for radiation therapy planning of canine sinonasal tumors reveals significant dosimetric differences

“…Acuros XB uses coupled Boltzmann transport equations and has been found to have very high dose prediction agreement with MC 33 . Consistent results were found in the present study and the previous study that compared model‐based algorithms (AAA and CCC) versus stimulation‐based methods (AXB and MC) 23 . The study performed by Nagata and Pethel used nine equally spaced coplanar radiation beams with sliding window technique IMRT.…”

“…Analytical dose calculation algorithms such as CCC typically have the greatest dosimetric discrepancy near air‐bone interfaces, 20,21 which are commonly noted in the radiation plans for dogs undergoing treatment for sinonasal cancer. A previous study compared dosimetry in anisotropic analytical algorithm (AAA) and Acuros XB (AXB) in canine sinonasal tumors and they observed the greatest overestimation of mean dose by AAA to the bone adjacent to planning target volume (PTV) for 3.7% 23 . Nonetheless, dosimetric inaccuracy near air‐bone interfaces has not yet been emphasized in veterinary radiation oncology.…”

“…A previous study compared dosimetry in anisotropic analytical algorithm (AAA) and Acuros XB (AXB) in canine sinonasal tumors and they observed the greatest overestimation of mean dose by AAA to the bone adjacent to planning target volume (PTV) for 3.7%. 23 Nonetheless, dosimetric inaccuracy near air-bone interfaces has not yet been emphasized in veterinary radiation oncology. Inaccurate dosimetry can lead to loss of tumor control or "double trouble" for the late responding tissues proposed by Dr.…”

Intensity‐modulated radiation therapy dose prescription and reporting: Sum and substance of the International Commission on Radiation Units and Measurements Report 83 for veterinary medicine

“…In the last decade, first original publications reported using IMRT in veterinary medicine, and a recent survey reported over 60% of veterinary radiation oncologists using IMRT . Some veterinary radiation oncologists use IMRT techniques for stereotactic radiation therapy (SRT) and stereotactic radiosurgery.…”

“…In consequence, the results of such studies are not quantitatively comparable. Fortunately, newer publications have been found, which apply the reporting recommendations with only few parameters (such as D 50% ) or no parameters missing …”