| Author: | Leung, Tsz Him |
| Title: | Comparison of normal tissue complication probability (NTCP) for brachial plexopathy between conventionally fractionated and hypofractionated breast radiation therapy |
| Advisors: | Wu, Vincent (HTI) |
| Degree: | M.Sc. |
| Year: | 2019 |
| Subject: | Hong Kong Polytechnic University -- Dissertations Cancer -- Radiotherapy -- Complications Breast -- Cancer -- Radiotherapy |
| Department: | Department of Health Technology and Informatics |
| Pages: | x, 71 pages : color illustrations |
| Language: | English |
| Abstract: | Introduction: Previous studies have showed that increase in dose per fraction in breast cancer radiotherapy (RT) was associated with higher risk of radiation-induced brachial plexopathy (RIBP). This complication is considered to be severe and there is no effective treatment. Purpose: This study aimed to evaluate and compare the normal tissue complication probability (NTCP) for RIBP between conventionally fractionated and hypofractionated breast cancer RT. Using the concept of biological effective dose (BED) and equivalent dose in 2Gy fractions (EQD2), volume of ipsilateral brachial plexus receiving =40Gy (V40) and its correlation with NTCP in different fractionation regimens were also evaluated. Materials & Methods: 27 subjects who were previously treated with three-dimensional conformal radiotherapy (3DCRT) to chest wall or breast with SCF irradiation were recruited in this retrospective study. A set of plans with three different fractionation regimens, including conventional 50Gy in 25 fractions, 42.5Gy in 16 fractions and 39Gy in 13 fractions, were generated for each patient. Ipsilateral brachial plexus contouring was performed on the CT image sets based on the RTOG guidelines. Dose-volume histograms (DVHs) of ipsilateral brachial plexus were exported from Eclipse treatment planning system (TPS) and converted into EQD₂-DVHs, which were then imported into the MATLAB program for equivalent uniform dose (EUD) and NTCP calculation. EQD₂-V40 of ipsilateral brachial plexus were also recorded from the generated EQD₂-DVHs. Difference in EUD, NTCP and EQD₂-V40 of ipsilateral brachial plexus among three different regimens were analyzed. Correlation between the NTCP and EQD₂-V40 of ipsilateral brachial plexus for each regimen was also analyzed. Results: The mean EQD₂-V40 of ipsilateral brachial plexus were 3.12 ± 0.77cm³, 3.10 ± 0.77cm³ and 3.07 ± 0.77cm³ for 25-fraction, 16-fraction and 13-fraction regimens respectively. The mean EUD of ipsilateral brachial plexus were 51.60 ± 3.41Gy, 65.81 ± 4.82Gy and 73.26 ± 5.60Gy for respective regimens. The mean NTCP of ipsilateral brachial plexus were 0.36 ± 0.26%, 14.81 ± 10.01% and 43.79 ± 22.65% for respective regimens. There were significant differences in EUD, NTCP and EQD₂-V40 of ipsilateral brachial plexus among the three regimens, and differences were significant between any two regimens. Correlation between NTCP and EQD₂-V40 was significant for each fractionation regime. Conclusion: Hypofractionated regimens could result in significantly higher NTCP for RIBP than that for conventionally fractionated regimen in 3DCRT for breast cancer, depending on dose per fraction. Conventionally fractionated regimen remains the optimal regimen for breast 3DCRT to minimize the risk of RIBP. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 991022197536703411.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 1.38 MB | Adobe PDF | View/Open |
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