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A comparison of dosimetric variance for external-beam partial breast irradiation using three-dimensional and four-dimensional computed tomography

Authors Li F, Li J, Wang W, Xu M, Li Y, Liu T

Received 16 November 2015

Accepted for publication 31 December 2015

Published 31 March 2016 Volume 2016:9 Pages 1857—1863


Checked for plagiarism Yes

Review by Single-blind

Peer reviewers approved by Dr Manfred Beleut

Peer reviewer comments 3

Editor who approved publication: Professor Daniele Santini

Bing Guo,1,2 Jian-Bin Li,2 Wei Wang,2 Min Xu,2 Yan-Kang Li,2,3 Tong-Hai Liu2

1School of Medicine and Life Sciences, University of Jinan-Shandong Academy of Medical Sciences, Jinan, Shandong Province, People’s Republic of China; 2Department of Radiation Oncology, Shandong Cancer Hospital & Institute, Jinan, Shandong Province, People’s Republic of China; 3School of Medicine, Shandong University, Jinan, Shandong Province, People’s Republic of China

Purpose: To investigate the potential dosimetric benefits from four-dimensional computed tomography (4DCT) compared with three-dimensional computed tomography (3DCT) in radiotherapy treatment planning for external-beam partial breast irradiation (EB-PBI).
Patients and methods: 3DCT and 4DCT scan sets were acquired for 20 patients who underwent EB-PBI. The volume of the tumor bed (TB) was determined based on seroma or surgical clips on 3DCT images (defined as TB3D) and the end inhalation (EI) and end exhalation (EE) phases of 4DCT images (defined as TBEI and TBEE, respectively). The clinical target volume (CTV) consisted of the TB plus a 1.0 cm margin. The planning target volume (PTV) was the CTV plus 0.5 cm (defined as PTV3D, PTVEI, and PTVEE). For each patient, a conventional 3D conformal plan (3D-CRT) was generated (defined as EB-PBI3D, EB-PBIEI, and EB-PBIEE).
Results: The PTV3D, PTVEI, and PTVEE were similar (P=0.549), but the PTV coverage of EB-PBI3D was significantly less than that of EB-PBIEI or EB-PBIEE (P=0.001 and P=0.025, respectively). There were no significant differences in the homogeneity or conformity indexes between the three treatment plans (P=0.125 and P=0.536, respectively). The EB-PBI3D plan resulted in the largest organs at risk dose.
Conclusion: There was a significant benefit for patients when using 3D-CRT based on 4DCT for EB-PBI with regard to reducing nontarget organ exposure. Respiratory motion did not affect the dosimetric distribution during free breathing, but might result in poor dose coverage when the PTV is determined using 3DCT.

Keywords: breast cancer, external-beam partial breast irradiation, three-dimensional computed tomography, four-dimensional computed tomography, dosimetric parameters

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