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Discrepancy between collapsed cone and Monte Carlo algorithms in lung inhomogeneity correction.

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Title: Discrepancy between collapsed cone and Monte Carlo algorithms in lung inhomogeneity correction.
Authors: Karimi AH; Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.; Division of Medical Physics, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran., Das IJ; Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, United States of America., Moharramkhani S; Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.; Division of Medical Physics, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran., Mirzaei H; Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran., Esposito M; The Abdus Salam International Centre for Theoretical Physics, Trieste, Italy., Geraily G; Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.; Division of Medical Physics, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran.
Source: Biomedical physics & engineering express [Biomed Phys Eng Express] 2026 Sep 11; Vol. 12 (5). Date of Electronic Publication: 2026 Sep 11.
Publication Type: Journal Article
Language: English
Journal Info: Publisher: IOP Publishing Ltd Country of Publication: England NLM ID: 101675002 Publication Model: Electronic Cited Medium: Internet ISSN: 2057-1976 (Electronic) Linking ISSN: 20571976 NLM ISO Abbreviation: Biomed Phys Eng Express Subsets: MEDLINE
Imprint Name(s): Original Publication: Bristol : IOP Publishing Ltd., [2015]-
MeSH Terms: Radiotherapy Planning, Computer-Assisted*/methods , Lung Neoplasms*/radiotherapy , Lung*/radiation effects , Carcinoma, Non-Small-Cell Lung*/radiotherapy , Algorithms* , Monte Carlo Method*, Radiosurgery/methods ; Humans ; Phantoms, Imaging ; Radiotherapy Dosage ; Photons
Abstract: Stereotactic body radiation therapy (SBRT) is a well-established standard of treatment for non-small cell lung cancer patients. However, SBRT is a double-edged sword and a high degree of accuracy is required for dose calculations. In the presence of inhomogeneity, it should be below 3% and depends strongly on the accuracy of the algorithm used for dose calculation in treatment planning system (TPS). The aim of this study is to evaluate the accuracy of collapsed cone (CC) algorithm for dose calculation in the presence of lung inhomogeneity compared to the Monte Carlo (MC) algorithm as the reference. The study conducted on a wide range of photon fields from 0.5 × 0.5 cm2to 10 × 10 cm2. Monaco® TPS equipped with CC and MC algorithms in 6 MV, 10 MV, and 18 MV photons was employed and the inhomogeneity correction factor and PPDs were calculated inside an in-house inhomogeneous phantom. Finally, the results were compared between two algorithms. For 6 MV photons, gamma index pass rate (GIPR) with (2 mm, 3%) criteria in a 0.5 × 0.5 cm2field is only 71.3%. The CC algorithm will not be able to confidently reproduce the PDDs in this field. For 1 × 1 cm2, 2 × 2 cm2, and 3 × 3 cm2fields, the accuracy of the CC algorithm can increase to above 98%. For SBRT of small lung lesions, the results recommend increasing the minimum segment width to >0.5 cm in IMRT plans if CC algorithm is used. Independent of field size, the accuracy of CC algorithm decreases with increasing energy. For 10 and 18 MV photons, average GIPR under (2 mm, 3%) criteria was 97.9% and 92.0%, respectively, which are not of clinical interest.
(© 2026 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)
Contributed Indexing: Keywords: Monte Carlo; SBRT; collapsed cone; lung inhomogeneity; small field dosimetry
Entry Date(s): Date Created: 20260903 Date Completed: 20260911 Latest Revision: 20260924
Update Code: 20260925
DOI: 10.1088/2057-1976/aea1f9
PMID: 42689954
Database: MEDLINE
FullText Text:
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PubType: Academic Journal
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  Data: Discrepancy between collapsed cone and Monte Carlo algorithms in lung inhomogeneity correction.
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  Data: <searchLink fieldCode="AU" term="%22Karimi+AH%22">Karimi AH</searchLink>; Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.; Division of Medical Physics, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran.<br /><searchLink fieldCode="AU" term="%22Das+IJ%22">Das IJ</searchLink>; Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, United States of America.<br /><searchLink fieldCode="AU" term="%22Moharramkhani+S%22">Moharramkhani S</searchLink>; Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.; Division of Medical Physics, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran.<br /><searchLink fieldCode="AU" term="%22Mirzaei+H%22">Mirzaei H</searchLink>; Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.<br /><searchLink fieldCode="AU" term="%22Esposito+M%22">Esposito M</searchLink>; The Abdus Salam International Centre for Theoretical Physics, Trieste, Italy.<br /><searchLink fieldCode="AU" term="%22Geraily+G%22">Geraily G</searchLink>; Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.; Division of Medical Physics, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran.
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  Data: <searchLink fieldCode="JN" term="%22101675002%22">Biomedical physics & engineering express</searchLink> [Biomed Phys Eng Express] 2026 Sep 11; Vol. 12 (5). <i>Date of Electronic Publication: </i>2026 Sep 11.
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  Data: <i>Publisher: </i><searchLink fieldCode="PB" term="%22IOP+Publishing+Ltd%22">IOP Publishing Ltd </searchLink><i>Country of Publication: </i>England <i>NLM ID: </i>101675002 <i>Publication Model: </i>Electronic <i>Cited Medium: </i>Internet <i>ISSN: </i>2057-1976 (Electronic) <i>Linking ISSN: </i><searchLink fieldCode="IS" term="%2220571976%22">20571976 </searchLink><i>NLM ISO Abbreviation: </i>Biomed Phys Eng Express <i>Subsets: </i>MEDLINE
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  Data: <i>Original Publication</i>: Bristol : IOP Publishing Ltd., [2015]-
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  Data: <searchLink fieldCode="MM" term="%22Radiotherapy+Planning%2C+Computer-Assisted%22">Radiotherapy Planning, Computer-Assisted*</searchLink>/<searchLink fieldCode="MM" term="%22Radiotherapy+Planning%2C+Computer-Assisted+methods%22">methods</searchLink> <br /><searchLink fieldCode="MM" term="%22Lung+Neoplasms%22">Lung Neoplasms*</searchLink>/<searchLink fieldCode="MM" term="%22Lung+Neoplasms+radiotherapy%22">radiotherapy</searchLink> <br /><searchLink fieldCode="MM" term="%22Lung%22">Lung*</searchLink>/<searchLink fieldCode="MM" term="%22Lung+radiation+effects%22">radiation effects</searchLink> <br /><searchLink fieldCode="MM" term="%22Carcinoma%2C+Non-Small-Cell+Lung%22">Carcinoma, Non-Small-Cell Lung*</searchLink>/<searchLink fieldCode="MM" term="%22Carcinoma%2C+Non-Small-Cell+Lung+radiotherapy%22">radiotherapy</searchLink> <br /><searchLink fieldCode="MM" term="%22Algorithms%22">Algorithms*</searchLink> <br /><searchLink fieldCode="MM" term="%22Monte+Carlo+Method%22">Monte Carlo Method*</searchLink><br /><searchLink fieldCode="MH" term="%22Radiosurgery%22">Radiosurgery</searchLink>/<searchLink fieldCode="MH" term="%22Radiosurgery+methods%22">methods</searchLink> ; <searchLink fieldCode="MH" term="%22Humans%22">Humans</searchLink> ; <searchLink fieldCode="MH" term="%22Phantoms%2C+Imaging%22">Phantoms, Imaging</searchLink> ; <searchLink fieldCode="MH" term="%22Radiotherapy+Dosage%22">Radiotherapy Dosage</searchLink> ; <searchLink fieldCode="MH" term="%22Photons%22">Photons</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Stereotactic body radiation therapy (SBRT) is a well-established standard of treatment for non-small cell lung cancer patients. However, SBRT is a double-edged sword and a high degree of accuracy is required for dose calculations. In the presence of inhomogeneity, it should be below 3% and depends strongly on the accuracy of the algorithm used for dose calculation in treatment planning system (TPS). The aim of this study is to evaluate the accuracy of collapsed cone (CC) algorithm for dose calculation in the presence of lung inhomogeneity compared to the Monte Carlo (MC) algorithm as the reference. The study conducted on a wide range of photon fields from 0.5 × 0.5 cm<superscript>2</superscript>to 10 × 10 cm<superscript>2</superscript>. Monaco® TPS equipped with CC and MC algorithms in 6 MV, 10 MV, and 18 MV photons was employed and the inhomogeneity correction factor and PPDs were calculated inside an in-house inhomogeneous phantom. Finally, the results were compared between two algorithms. For 6 MV photons, gamma index pass rate (GIPR) with (2 mm, 3%) criteria in a 0.5 × 0.5 cm<superscript>2</superscript>field is only 71.3%. The CC algorithm will not be able to confidently reproduce the PDDs in this field. For 1 × 1 cm<superscript>2</superscript>, 2 × 2 cm<superscript>2</superscript>, and 3 × 3 cm<superscript>2</superscript>fields, the accuracy of the CC algorithm can increase to above 98%. For SBRT of small lung lesions, the results recommend increasing the minimum segment width to >0.5 cm in IMRT plans if CC algorithm is used. Independent of field size, the accuracy of CC algorithm decreases with increasing energy. For 10 and 18 MV photons, average GIPR under (2 mm, 3%) criteria was 97.9% and 92.0%, respectively, which are not of clinical interest.<br /> (© 2026 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)
– Name: SubjectMinor
  Label: Contributed Indexing
  Group:
  Data: <i>Keywords: </i>Monte Carlo; SBRT; collapsed cone; lung inhomogeneity; small field dosimetry
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  Data: <i>Date Created: </i>20260903 <i>Date Completed: </i>20260911 <i>Latest Revision: </i>20260924
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  Data: 10.1088/2057-1976/aea1f9
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  Data: 42689954
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=cmedm&AN=42689954
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        Value: 10.1088/2057-1976/aea1f9
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      – Code: eng
        Text: English
    Subjects:
      – SubjectFull: Radiosurgery methods
        Type: general
      – SubjectFull: Humans
        Type: general
      – SubjectFull: Phantoms, Imaging
        Type: general
      – SubjectFull: Radiotherapy Dosage
        Type: general
      – SubjectFull: Photons
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      – SubjectFull: Radiotherapy Planning, Computer-Assisted methods
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      – SubjectFull: Lung Neoplasms radiotherapy
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      – SubjectFull: Carcinoma, Non-Small-Cell Lung radiotherapy
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      – SubjectFull: Monte Carlo Method
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      – TitleFull: Discrepancy between collapsed cone and Monte Carlo algorithms in lung inhomogeneity correction.
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              Text: 2026 Sep 11
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