Irradiation of lung and esophagus tumors: A comparison of dose distributions calculated by anisotropic analytical algorithm and pencil beam convolution algorithm, a retrospective dosimetric study

Emmanuel Amankwaa-Frempong, Frederik Vernimmen, Samuel Nguah Blay, Ramalingam Ezhilalan


Purpose: The aim of this study was to evaluate dosimetric differences between pencil beam convolution (PBC) algorithm and anisotropic analytical algorithm (AAA) calculations in patients with lung and esophageal cancers.

Methods: The existing plans calculated with PBC for 60 patients treated in 2012 were recalculated with AAA maintaining the same beam geometry and dose monitor units.  For these plans, dose prescription ranges were 41.4 Gy to 56.0 Gy for esophageal cancers and 50.0 Gy to 64.0 Gy for lung cancers. Dosimetric variables were the 95% PTV coverage, mean PTV dose, maximum spinal cord dose, lung V5Gy, and lung V20Gy.

Results: The 95% PTV coverage’s for both lung and esophageal tumors were reduced when recalculated with AAA. Maximum spinal cord doses for lung cancer patients were reduced by 0.7 Gy and by 0.3 Gy for esophageal cancer patients on AAA. On the other hand, lung V5Gy had 3.5% increase for both lung and esophageal cancer patients on AAA, whereas lung V20Gy increased by 1.5% also on AAA for esophageal cancer patients.

Conclusion: These clinical results confirm the differences between AAA and PBC algorithms as observed in phantom dosimetric studies, and give an indication of the clinical implications of changing from one calculation algorithm to another.


Cite this article as: Amankwaa-Frempong E, Vernimmen F, Blay S, Ezhilalan R. Irradiation of lung and esophagus tumors: A comparison of dose distributions calculated by anisotropic analytical algorithm and pencil beam convolution algorithm, a retrospective dosimetric study. Int J Cancer Ther Oncol 2014; 2(2):020210. DOI: 10.14319/ijcto.0202.10


Anisotropic Analytical Algorithm; Pencil Beam Convolution; Lung Cancer; Organs At Risk (OAR)

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