Difference in dose-volumetric data between the analytical anisotropic algorithm, the dose-to-medium, and the dose-to-water reporting modes of the Acuros XB for lung stereotactic body radiation therapy.

Wambaka A Mampuya,Mitsuhiro Nakamura,Yoshinori Hirose,Masahiro Hiraoka,Takashi Mizowaki,Kenji Kitsuda,Takashi Ishigaki

doi:10.1120/jacmp.v17i5.6338

Wambaka A Mampuya, Mitsuhiro Nakamura + Show 5 more

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https://doi.org/10.1120/jacmp.v17i5.6338

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Abstract

The purpose of this study was to evaluate the difference in dose‐volumetric data between the analytical anisotropic algorithms (AAA) and the two dose reporting modes of the Acuros XB, namely, the dose to water (AXB−Dw) and dose to medium (AXB−Dm) in lung stereotactic body radiotherapy (SBRT). Thirty‐eight plans were generated using the AXB−Dm in Eclipse Treatment Planning System (TPS) and then recalculated with the AXB−Dw and AAA, using identical beam setup. A dose of 50 Gy in 4 fractions was prescribed to the isocenter and the planning target volume (PTV) D95%. The isocenter was always inside the PTV. The following dose‐volumetric parameters were evaluated; D2%, D50%, D95%, and D98% for the internal target volume (ITV) and the PTV. Two‐tailed paired Student's t‐tests determined the statistical significance. Although for most of the parameters evaluated, the mean differences observed between the AAA, AXB−Dmand AXB−Dw were statistically significant (p<0.05), absolute differences were rather small, in general less than 5% points. The maximum mean difference was observed in the ITV D50% between the AXB−Dm and the AAA and was 1.7% points under the isocenter prescription and 3.3% points under the D95 prescription. AXB−Dm produced higher values than AXB−Dw with differences ranging from 0.4 to 1.1% points under isocenter prescription and 0.0 to 0.7% points under the PTV D95% prescription. The differences observed under the PTV D95% prescription were larger compared to those observed for the isocenter prescription between AXB−Dm and AAA, AXB−Dm and AXB−Dw, and AXB−Dw and AAA. Although statistically significant, the mean differences between the three algorithms are within 3.3% points.PACS number(s): 87.55.x, 87.55.D‐, 87.55.dk

Highlights

The field of radiation oncology has rapidly evolved over the last three decades due to the advances in diagnostic radiology that allows for better tumor volume definition during treatment planning, and the development of new irradiation techniques such as intensity-modulated a Corresponding author: Mitsuhiro Nakamura, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan; phone: (+81)-75-751-3762; fax: (+81)-75-771-9749; email: radiotherapy (IMRT) and stereotactic body radiation therapy (SBRT), making possible a better optimization of dose distribution around the planning target volume (PTV).(1) Those advanced techniques require a high and verified accuracy in dose calculation to ensure that the prescribed dose is delivered to the tumor with good sparing of the surrounding normal tissues
The purpose of this study was to evaluate the difference in dose-volumetric data between the analytical anisotropic algorithms (AAA) and the two dose reporting modes of the Acuros XB, namely, the dose to water (AXB_Dw) and dose to medium (AXB_Dm) in lung stereotactic body radiotherapy (SBRT)
Boltzmann Transportation Equations (LBTE), is considered as the gold standard in terms of accuracy, especially in heterogeneous media such as lung.[5]. Monte Carlo (MC) explicitly models the physical interaction of each particle in media, a process which remains time-consuming despite recent advances in computing power

Summary

Introduction

The field of radiation oncology has rapidly evolved over the last three decades due to the advances in diagnostic radiology that allows for better tumor volume definition during treatment planning, and the development of new irradiation techniques such as intensity-modulated a Corresponding author: Mitsuhiro Nakamura, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan; phone: (+81)-75-751-3762; fax: (+81)-75-771-9749; email: radiotherapy (IMRT) and stereotactic body radiation therapy (SBRT), making possible a better optimization of dose distribution around the planning target volume (PTV).(1) Those advanced techniques require a high and verified accuracy in dose calculation to ensure that the prescribed dose is delivered to the tumor with good sparing of the surrounding normal tissues. Boltzmann Transportation Equations (LBTE), is considered as the gold standard in terms of accuracy, especially in heterogeneous media such as lung.[5] MC explicitly models the physical interaction of each particle in media, a process which remains time-consuming despite recent advances in computing power This explains why MC is still not widely used in daily clinical practice.[5,6] Recently, another dose calculation algorithm using a deterministic grid-based. They reported a substantial decrease in the water-to-medium stopping power for the lung with an increase in the monoenergetic electron energy, suggesting that the difference between Dm and

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