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Title: Monte Carlo evaluation of the AAA treatment planning algorithm in a heterogeneous multilayer phantom and IMRT clinical treatments for an Elekta SL25 linear accelerator

Abstract

The Anisotropic Analytical Algorithm (AAA) is a new pencil beam convolution/superposition algorithm proposed by Varian for photon dose calculations. The configuration of AAA depends on linear accelerator design and specifications. The purpose of this study was to investigate the accuracy of AAA for an Elekta SL25 linear accelerator for small fields and intensity modulated radiation therapy (IMRT) treatments in inhomogeneous media. The accuracy of AAA was evaluated in two studies. First, AAA was compared both with Monte Carlo (MC) and the measurements in an inhomogeneous phantom simulating lung equivalent tissues and bone ribs. The algorithm was tested under lateral electronic disequilibrium conditions, using small fields (2x2 cm{sup 2}). Good agreement was generally achieved for depth dose and profiles, with deviations generally below 3% in lung inhomogeneities and below 5% at interfaces. However, the effects of attenuation and scattering close to the bone ribs were not fully taken into account by AAA, and small inhomogeneities may lead to planning errors. Second, AAA and MC were compared for IMRT plans in clinical conditions, i.e., dose calculations in a computed tomography scan of a patient. One ethmoid tumor, one orophaxynx and two lung tumors are presented in this paper. Small differences were foundmore » between the dose volume histograms. For instance, a 1.7% difference for the mean planning target volume dose was obtained for the ethmoid case. Since better agreement was achieved for the same plans but in homogeneous conditions, these differences must be attributed to the handling of inhomogeneities by AAA. Therefore, inherent assumptions of the algorithm, principally the assumption of independent depth and lateral directions in the scaling of the kernels, were slightly influencing AAA's validity in inhomogeneities. However, AAA showed a good accuracy overall and a great ability to handle small fields in inhomogeneous media compared to other pencil beam convolution algorithms.« less

Authors:
; ; ; ;  [1];  [2];  [2]
  1. Department of Radiotherapy, St-Luc University Hospital, 10 av. Hippocrate, 1200 Brussels (Belgium)
  2. (Belgium)
Publication Date:
OSTI Identifier:
20951297
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 34; Journal Issue: 5; Other Information: DOI: 10.1118/1.2727314; (c) 2007 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ACCURACY; ALGORITHMS; COMPUTERIZED TOMOGRAPHY; DEPTH DOSE DISTRIBUTIONS; LINEAR ACCELERATORS; LUNGS; MONTE CARLO METHOD; NEOPLASMS; PHANTOMS; RADIATION DOSES; RADIOTHERAPY; SKELETON

Citation Formats

Sterpin, E., Tomsej, M., Smedt, B. de, Reynaert, N., Vynckier, S., Department of Medical Physics, Ghent University, Proeftuistraat 86, 9000 Ghent, and Department of Radiotherapy, St-Luc University Hospital, 10 av. Hippocrate, 1200 Brussels. Monte Carlo evaluation of the AAA treatment planning algorithm in a heterogeneous multilayer phantom and IMRT clinical treatments for an Elekta SL25 linear accelerator. United States: N. p., 2007. Web. doi:10.1118/1.2727314.
Sterpin, E., Tomsej, M., Smedt, B. de, Reynaert, N., Vynckier, S., Department of Medical Physics, Ghent University, Proeftuistraat 86, 9000 Ghent, & Department of Radiotherapy, St-Luc University Hospital, 10 av. Hippocrate, 1200 Brussels. Monte Carlo evaluation of the AAA treatment planning algorithm in a heterogeneous multilayer phantom and IMRT clinical treatments for an Elekta SL25 linear accelerator. United States. doi:10.1118/1.2727314.
Sterpin, E., Tomsej, M., Smedt, B. de, Reynaert, N., Vynckier, S., Department of Medical Physics, Ghent University, Proeftuistraat 86, 9000 Ghent, and Department of Radiotherapy, St-Luc University Hospital, 10 av. Hippocrate, 1200 Brussels. Tue . "Monte Carlo evaluation of the AAA treatment planning algorithm in a heterogeneous multilayer phantom and IMRT clinical treatments for an Elekta SL25 linear accelerator". United States. doi:10.1118/1.2727314.
@article{osti_20951297,
title = {Monte Carlo evaluation of the AAA treatment planning algorithm in a heterogeneous multilayer phantom and IMRT clinical treatments for an Elekta SL25 linear accelerator},
author = {Sterpin, E. and Tomsej, M. and Smedt, B. de and Reynaert, N. and Vynckier, S. and Department of Medical Physics, Ghent University, Proeftuistraat 86, 9000 Ghent and Department of Radiotherapy, St-Luc University Hospital, 10 av. Hippocrate, 1200 Brussels},
abstractNote = {The Anisotropic Analytical Algorithm (AAA) is a new pencil beam convolution/superposition algorithm proposed by Varian for photon dose calculations. The configuration of AAA depends on linear accelerator design and specifications. The purpose of this study was to investigate the accuracy of AAA for an Elekta SL25 linear accelerator for small fields and intensity modulated radiation therapy (IMRT) treatments in inhomogeneous media. The accuracy of AAA was evaluated in two studies. First, AAA was compared both with Monte Carlo (MC) and the measurements in an inhomogeneous phantom simulating lung equivalent tissues and bone ribs. The algorithm was tested under lateral electronic disequilibrium conditions, using small fields (2x2 cm{sup 2}). Good agreement was generally achieved for depth dose and profiles, with deviations generally below 3% in lung inhomogeneities and below 5% at interfaces. However, the effects of attenuation and scattering close to the bone ribs were not fully taken into account by AAA, and small inhomogeneities may lead to planning errors. Second, AAA and MC were compared for IMRT plans in clinical conditions, i.e., dose calculations in a computed tomography scan of a patient. One ethmoid tumor, one orophaxynx and two lung tumors are presented in this paper. Small differences were found between the dose volume histograms. For instance, a 1.7% difference for the mean planning target volume dose was obtained for the ethmoid case. Since better agreement was achieved for the same plans but in homogeneous conditions, these differences must be attributed to the handling of inhomogeneities by AAA. Therefore, inherent assumptions of the algorithm, principally the assumption of independent depth and lateral directions in the scaling of the kernels, were slightly influencing AAA's validity in inhomogeneities. However, AAA showed a good accuracy overall and a great ability to handle small fields in inhomogeneous media compared to other pencil beam convolution algorithms.},
doi = {10.1118/1.2727314},
journal = {Medical Physics},
number = 5,
volume = 34,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}