Dose calculation algorithm accuracy for small fields in non-homogeneous media: The lung SBRT case

  • Antonella Fogliata
    Corresponding author.
    Humanitas Research Hospital and Cancer Center, Radiotherapy and Radiosurgery Dept, via Manzoni 56, 20089 Milan-Rozzano, Italy
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  • Luca Cozzi
    Humanitas Research Hospital and Cancer Center, Radiotherapy and Radiosurgery Dept, via Manzoni 56, 20089 Milan-Rozzano, Italy

    Humanitas University, Biomedical Science Faculty, via Manzoni 118, 20089 Milan-Rozzano, Italy
    Search for articles by this author
Published:November 24, 2016DOI:


      • The literature regarding the lung SBRT dose calculation algorithm accuracy is reviewed.
      • The small field and low density problems are analysed.
      • A summarizing example focuses on the main differences and aspects of the main three classes of dose calculation algorithms.


      This review addresses the theme of dose calculation accuracy in the case of the stereotactic treatment of lung lesions. Based on the classical categories of type “a”, “b” and “c” algorithms (according to their degree of complexity in the management of charged particle transport), a summary of findings from literature is reported.
      Two main critical areas have been identified: the use of small fields and the presence of low density medium. Concerning the latter point, the algorithm accuracy is intrinsic of the algorithm core, and, notwithstanding the materials discretization and their chemical composition knowledge, type “c” are, at the most, able to reproduce the actual physical dose distribution in heterogeneous media. For what concerns the small field management, the final accuracy could be strongly related to the beam configuration appropriateness in the TPS (as well for MC this relates to the proper linac head description).
      As a very crude summary, type “a” should be considered as unsuitable for this kind of treatment calculations (with differences of the order of 20–30%), while type “b” and “c” could keep their accuracy approximatively within 10 and 5%, respectively.


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