open access

Vol 25, No 4 (2020)
Original research articles
Published online: 2020-07-01
Submitted: 2019-11-08
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6X Acuros algorithm validation in the presence of inhomogeneities for VMAT treatment planning

Sarah Bassi, Elaine Tyner
DOI: 10.1016/j.rpor.2020.03.018
·
Rep Pract Oncol Radiother 2020;25(4):539-547.

open access

Vol 25, No 4 (2020)
Original research articles
Published online: 2020-07-01
Submitted: 2019-11-08

Abstract

Aim

To validate the Acuros®XB (AXB) dose calculation algorithm for a 6 MV beam from the Varian TrueBeam treatment units.

Background

Currently Anisotropic Analytic Algorithm (AAA) is clinically used on authors’ department but AXB could replace it for VMAT treatments in regions where inhomogeneities and free air are present.

Materials and methods

Two steps are followed in the validation process of a new dose calculation algorithm. The first is to check the accuracy of algorithm for a homogenous phantom and regular fields. Multiple fields of increasing complexity have been acquired using a MapCheck diode array. The accuracy of the algorithm was evaluated using the gamma analysis method. The second is to validate the algorithm in the presence of heterogeneous media. Planar absolute dose was measured with GafChromic®EBT2 film and was compared with the dose calculated by AXB. Gamma analysis was performed between MapCheck measurements and AXB dose calculations, at a range of clinical source-surface distance.

Results

For SSDs ranging from 80 to 100 cm, the results show a minimum pass rate of 95% between AXB and MapCheck acquisition. For open 6 MV photon beam interacting with a phantom with an air gap, the agreement after the air gap between AXB and GafChromic®EBT2 is less than 1% in the 3 × 3cm2 field and less than 2% in the 10 × 10 cm2 field.

Conclusions

AXB has advanced modelling of lateral electron transport that enables a more accurate dose calculation in heterogeneous regions and, compared with AAA, improves accuracy between different density interfaces. This will be of particular benefit for head/neck treatments.

Abstract

Aim

To validate the Acuros®XB (AXB) dose calculation algorithm for a 6 MV beam from the Varian TrueBeam treatment units.

Background

Currently Anisotropic Analytic Algorithm (AAA) is clinically used on authors’ department but AXB could replace it for VMAT treatments in regions where inhomogeneities and free air are present.

Materials and methods

Two steps are followed in the validation process of a new dose calculation algorithm. The first is to check the accuracy of algorithm for a homogenous phantom and regular fields. Multiple fields of increasing complexity have been acquired using a MapCheck diode array. The accuracy of the algorithm was evaluated using the gamma analysis method. The second is to validate the algorithm in the presence of heterogeneous media. Planar absolute dose was measured with GafChromic®EBT2 film and was compared with the dose calculated by AXB. Gamma analysis was performed between MapCheck measurements and AXB dose calculations, at a range of clinical source-surface distance.

Results

For SSDs ranging from 80 to 100 cm, the results show a minimum pass rate of 95% between AXB and MapCheck acquisition. For open 6 MV photon beam interacting with a phantom with an air gap, the agreement after the air gap between AXB and GafChromic®EBT2 is less than 1% in the 3 × 3cm2 field and less than 2% in the 10 × 10 cm2 field.

Conclusions

AXB has advanced modelling of lateral electron transport that enables a more accurate dose calculation in heterogeneous regions and, compared with AAA, improves accuracy between different density interfaces. This will be of particular benefit for head/neck treatments.

Get Citation

Keywords

Acuros®XB (AXB) version 13.7 algorithm; Anisotropic Analytic Algorithm; GafChromic® EBT2; MapCheck measurements; VMAT treatment plans.

About this article
Title

6X Acuros algorithm validation in the presence of inhomogeneities for VMAT treatment planning

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 25, No 4 (2020)

Pages

539-547

Published online

2020-07-01

DOI

10.1016/j.rpor.2020.03.018

Bibliographic record

Rep Pract Oncol Radiother 2020;25(4):539-547.

Keywords

Acuros®XB (AXB) version 13.7 algorithm
Anisotropic Analytic Algorithm
GafChromic® EBT2
MapCheck measurements
VMAT treatment plans.

Authors

Sarah Bassi
Elaine Tyner

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