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Title: An independent dose calculation algorithm for MLC-based stereotactic radiotherapy

Abstract

We have developed an algorithm to calculate dose in a homogeneous phantom for radiotherapy fields defined by multi-leaf collimator (MLC) for both static and dynamic MLC delivery. The algorithm was developed to supplement the dose algorithms of the commercial treatment planning systems (TPS). The motivation for this work is to provide an independent dose calculation primarily for quality assurance (QA) and secondarily for the development of static MLC field based inverse planning. The dose calculation utilizes a pencil-beam kernel. However, an explicit analytical integration results in a closed form for rectangular-shaped beamlets, defined by single leaf pairs. This approach reduces spatial integration to summation, and leads to a simple method of determination of model parameters. The total dose for any static or dynamic MLC field is obtained by summing over all individual rectangles from each segment which offers faster speed to calculate two-dimensional dose distributions at any depth in the phantom. Standard beam data used in the commissioning of the TPS was used as input data for the algorithm. The calculated results were compared with the TPS and measurements for static and dynamic MLC. The agreement was very good (<2.5%) for all tested cases except for very small static MLCmore » sizes of 0.6 cmx0.6 cm (<6%) and some ion chamber measurements in a high gradient region (<4.4%). This finding enables us to use the algorithm for routine QA as well as for research developments.« less

Authors:
; ; ;  [1];  [2];  [3];  [2]
  1. Department of Radiation Oncology, Mannheim Medical Center, University of Heidelberg, Mannheim, 68167 (Germany)
  2. (United States)
  3. (Germany)
Publication Date:
OSTI Identifier:
20951291
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 34; Journal Issue: 5; Other Information: DOI: 10.1118/1.2717385; (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; ALGORITHMS; BEAMS; COLLIMATORS; COMMISSIONING; DOSIMETRY; IONIZATION CHAMBERS; KERNELS; PHANTOMS; QUALITY ASSURANCE; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIOTHERAPY

Citation Formats

Lorenz, Friedlieb, Killoran, Joseph H., Wenz, Frederik, Zygmanski, Piotr, Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, Department of Radiation Oncology, Mannheim Medical Center, University of Heidelberg, Mannheim, 68167, and Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115. An independent dose calculation algorithm for MLC-based stereotactic radiotherapy. United States: N. p., 2007. Web. doi:10.1118/1.2717385.
Lorenz, Friedlieb, Killoran, Joseph H., Wenz, Frederik, Zygmanski, Piotr, Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, Department of Radiation Oncology, Mannheim Medical Center, University of Heidelberg, Mannheim, 68167, & Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115. An independent dose calculation algorithm for MLC-based stereotactic radiotherapy. United States. doi:10.1118/1.2717385.
Lorenz, Friedlieb, Killoran, Joseph H., Wenz, Frederik, Zygmanski, Piotr, Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, Department of Radiation Oncology, Mannheim Medical Center, University of Heidelberg, Mannheim, 68167, and Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115. Tue . "An independent dose calculation algorithm for MLC-based stereotactic radiotherapy". United States. doi:10.1118/1.2717385.
@article{osti_20951291,
title = {An independent dose calculation algorithm for MLC-based stereotactic radiotherapy},
author = {Lorenz, Friedlieb and Killoran, Joseph H. and Wenz, Frederik and Zygmanski, Piotr and Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115 and Department of Radiation Oncology, Mannheim Medical Center, University of Heidelberg, Mannheim, 68167 and Department of Radiation Oncology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115},
abstractNote = {We have developed an algorithm to calculate dose in a homogeneous phantom for radiotherapy fields defined by multi-leaf collimator (MLC) for both static and dynamic MLC delivery. The algorithm was developed to supplement the dose algorithms of the commercial treatment planning systems (TPS). The motivation for this work is to provide an independent dose calculation primarily for quality assurance (QA) and secondarily for the development of static MLC field based inverse planning. The dose calculation utilizes a pencil-beam kernel. However, an explicit analytical integration results in a closed form for rectangular-shaped beamlets, defined by single leaf pairs. This approach reduces spatial integration to summation, and leads to a simple method of determination of model parameters. The total dose for any static or dynamic MLC field is obtained by summing over all individual rectangles from each segment which offers faster speed to calculate two-dimensional dose distributions at any depth in the phantom. Standard beam data used in the commissioning of the TPS was used as input data for the algorithm. The calculated results were compared with the TPS and measurements for static and dynamic MLC. The agreement was very good (<2.5%) for all tested cases except for very small static MLC sizes of 0.6 cmx0.6 cm (<6%) and some ion chamber measurements in a high gradient region (<4.4%). This finding enables us to use the algorithm for routine QA as well as for research developments.},
doi = {10.1118/1.2717385},
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}
}