Clinical implementation and evaluation of the Acuros dose calculation algorithm

Abstract

PurposeThe main aim of this study is to validate the Acuros XB dose calculation algorithm for a Varian Clinac iX linac in our clinics, and subsequently compare it with the wildely used AAA algorithm.Methods and materialsThe source models for both Acuros XB and AAA were configured by importing the same measured beam data into Eclipse treatment planning system. Both algorithms were validated by comparing calculated dose with measured dose on a homogeneous water phantom for field sizes ranging from 6 cm × 6 cm to 40 cm × 40 cm. Central axis and off‐axis points with different depths were chosen for the comparison. In addition, the accuracy of Acuros was evaluated for wedge fields with wedge angles from 15 to 60°. Similarly, variable field sizes for an inhomogeneous phantom were chosen to validate the Acuros algorithm. In addition, doses calculated by Acuros and AAA at the center of lung equivalent tissue from three different VMAT plans were compared to the ion chamber measured doses in QUASAR phantom, and the calculated dose distributions by the two algorithms and their differences on patients were compared. Computation time on VMAT plans was also evaluated for Acuros and AAA. Differences between dose‐to‐water (calculated by AAA and Acuros XB) and dose‐to‐medium (calculated by Acuros XB) on patient plans were compared and evaluated.ResultsFor open 6 MV photon beams on the homogeneous water phantom, both Acuros XB and AAA calculations were within 1% of measurements. For 23 MV photon beams, the calculated doses were within 1.5% of measured doses for Acuros XB and 2% for AAA. Testing on the inhomogeneous phantom demonstrated that AAA overestimated doses by up to 8.96% at a point close to lung/solid water interface, while Acuros XB reduced that to 1.64%. The test on QUASAR phantom showed that Acuros achieved better agreement in lung equivalent tissue while AAA underestimated dose for all VMAT plans by up to 2.7%. Acuros XB computation time was about three times faster than AAA for VMAT plans, and computation time for other plans will be discussed at the end. Maximum difference between dose calculated by AAA and dose‐to‐medium by Acuros XB (Acuros_Dm,m) was 4.3% on patient plans at the isocenter, and maximum difference between D100 calculated by AAA and by Acuros_Dm,m was 11.3%. When calculating the maximum dose to spinal cord on patient plans, differences between dose calculated by AAA and Acuros_Dm,m were more than 3%.ConclusionCompared with AAA, Acuros XB improves accuracy in the presence of inhomogeneity, and also significantly reduces computation time for VMAT plans. Dose differences between AAA and Acuros_Dw,m were generally less than the dose differences between AAA and Acuros_Dm,m. Clinical practitioners should consider making Acuros XB available in clinics, however, further investigation and clarification is needed about which dose reporting mode (dose‐to‐water or dose‐to‐medium) should be used in clinics.

Validation of the preconfigured Varian Ethos Acuros XB Beam Model for treatment planning dose calculations: A dosimetric study

“…Based on the results, they concluded that AXB was more appropriate to use for dose calculations when low‐density heterogeneities were involved. Other studies 35–37 have drawn similar conclusions, that although both the AXB and the AAA algorithm can meet the RTOG 0813 dosimetric criteria, in general, AXB presented an improved dosimetric accuracy in the presence of inhomogeneity.…”

“…Based on the results, they concluded that AXB was more appropriate to use for dose calculations when low-density heterogeneities were involved. Other studies [35][36][37] have drawn similar conclusions, that although both the AXB and heterogeneous tissues or tissue interfaces, it was most likely due to differences in the algorithm. It can also be seen that the Halcyon AAA model tends to predict higher doses in the lung/tissue interface, which is consistent with previous literature.…”

Dose to medium in head and neck radiotherapy: Clinical implications for target volume metrics

“…The dosimetric accuracy of LBTE has been investigated for a range of materials and treatment geometries and techniques [6][7][8][9], the findings generally indicating improved accuracy of the LBTE algorithm over Type B algorithms. The impact of reporting to D w and D m has been discussed for lung [10][11][12], breast [13], bone [14,15] and head and neck [16][17][18]. Recommendations have also been made for reporting dose in the routine clinical setting and in clinical trials [4,19] in the context of both Monte Carlo and LBTE algorithms.…”

An efficient planning technique for low dose whole lung radiation therapy for covid-19 pandemic patients

“…In this work, the ArucosXB algorithm was used and the lung consolidation was considered to improve dose calculation accuracy inside lung. AcurosXB has been shown to be more accurate than the convolution-superposition type of algorithms, especially in the low density lung tissues and the lung soft tissue interface [16,17]. However, we realized that the determination of lung consolidation level from either chest X-ray or an OBI image may have large uncertainty.…”