Dosimetric evaluation of the Acuros XB algorithm for a 4 MV photon beam in head and neck intensity‐modulated radiation therapy
نویسندگان
چکیده
In this study, we assessed the differences in the dose distribution of a 4 MV photon beam among different calculation algorithms: the Acuros XB (AXB) algorithm, the analytic anisotropic algorithm (AAA), and the pencil beam convolution (PBC) algorithm (ver. 11.0.31), in phantoms and in clinical intensity-modulated radiation therapy (IMRT) plans. Homogeneous and heterogeneous, including middle-, low-, and high-density, phantoms were combined to assess the percentage depth dose and lateral dose profiles among AXB, AAA, and PBC. For the phantom containing the low-density area, AXB was in agreement with measurement within 0.5%, while the greatest differences between the AAA and PBC calculations and measurement were 2.7% and 3.6%, respectively. AXB showed agreement with measurement within 2.5% at the high-density area, while AAA and PBC overestimated the dose by more than 4.5% and 4.0%, respectively. Furthermore, 15 IMRT plans, calculated using AXB, for oropharyngeal, hypopharyngeal, and laryngeal carcinomas were analyzed. The dose prescription was 70 Gy to 50% of the planning target volume (PTV70). Subsequently, each plan was recalculated using AAA and PBC while maintaining the AXB-calculated monitor units, leaf motion, and beam arrangement. Additionally, nine hypopharyngeal and laryngeal cancer patients were analyzed in terms of PTV70 for cartilaginous structures (PTV(70_cartilage)). The doses covering 50% to PTV70 calculated by AAA and PBC were 2.1% ± 1.0% and 3.7% ± 0.8% significantly higher than those using AXB, respectively (p < 0.01). The increases in doses to PTV(70_cartilage) calculated by AAA and PBC relative to AXB were 3.9% and 5.3% on average, respectively, and were relatively greater than those in the entire PTV70. AXB was found to be in better agreement with measurement in phantoms in heterogeneous areas for the 4 MV photon beam. Considering AXB as the standard, AAA and PBC overestimated the IMRT dose for head and neck cancer. The dosimetric differences should not be ignored, particularly with cartilaginous structures in PTV.
منابع مشابه
Dosimetric verification of pre-treatment intensity modulated radiation therapy in the commissioning process
Background: Commissioning tests are recommended before implementing Intensity Modulated Radiation Therapy. This study evaluated five different plans of IMRT mocks for different modulation indices. Materials and Methods: IMRT tests were done in slab phantom for both 6MV and 15 MV photon energies using a 2D array ion chamber dosimeter. Results: The acceptance criteria were based on 3% /3mm. All t...
متن کاملDosimetric accuracy of the Acuros XB and Anisotropic analytical algorithm near interface of the different density media for the small fields of a 6- MV flattening-filter-free beam
Background: This study was conducted to assess the accuracy of dose calculation near the air-phantom interface of a heterogeneous phantom for Acuros XB (AXB) and Anisotropic Analytical Algorithm (AAA) algorithm of a 6-MV flattening-filter-free beam, compared with film measurements. Materials and Methods: A phantom included air gap was ...
متن کامل3-Dimensional conformal radiotherapy versus intensity modulated radiotherapy for localized prostate cancer: Dosimetric and radiobiologic analysis
Background: To analyze the dosimetric and radio biologic advantages between intensity modulated radiotherapy (IMRT) and 3 dimensional conformal radiotherapy (3DCRT) and selection of optimal photon energy for IMRT treatments. Material and methods: 24 patients with localized prostate carcinoma were planned for 3DCRT and IMRT techniques. Radiation dose of 54 Gy with 2 Gy/fraction, was planned to ...
متن کاملUsing Varian Photon Beam Source Model for Dose Calculation of Small Fields
The use of small fi elds in radiotherapy techniques has increased substantially, in particular in stereotactic treatments and large uniform or nonuniform fi elds that are composed of small fi elds, such as for intensity-modulated radiation therapy (IMRT). This clinical perspective will focus on an experimental evaluation of the dose calculation accuracy of the anisotropic analytical algorithm (...
متن کاملThe effect of high energy photon beam in dose- volume parameters and integral dose of normal structures in Head and neck IMRT
Introduction: The aim of this study is to investigate the effect of partially used high photon energies on dosimetric parameters and integral doses of nasopharynx IMRT plans. Materials and Methods: Two 7 coplanar IMRT plan were created for eleven patients (6 MV only IMRT plan in both phase1 and phase2 and 6 MV phase1-mixed energies (6 MV and 15 MV) phase2...
متن کامل