Role of deep inspiration breath hold on post-operative radiotherapy of right-sided breast cancer
Benedict Ian Torno,
Philippines
PO-2329
Abstract
Role of deep inspiration breath hold on post-operative radiotherapy of right-sided breast cancer
Authors: Benedict Ian Torno1, Norberto Abella2, Carlos Josef Villafuerte2, Manuel Martin Lopez2
1Perpetual Help Medical Center- Las Pinas, Radiation Oncology, Las Pinas, Philippines; 2Perpetual Help Medical Center-Las Pinas, Radiation Oncology, Las Pinas, Philippines
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Purpose or Objective
This study aims to establish the role of deep inspiration breath hold (DIBH) in reducing radiation dose exposure of the organs at risk (OARs) in right-sided breast cancer patients, namely the lungs, liver, and heart.
Material and Methods
A total of 20 patients referred for post-operative locoregional radiotherapy (RT) were included in this study. Two Non-Contrast Computed Tomography (CT) data sets were acquired from each patient, one for the free breathing (FB) scan and another for the DIBH scan. Following the acquisition of CT data sets, the target volumes (chest wall and the regional nodes composed of the supraclavicular, axillary, and internal mammary lymph nodes), as well as the OARs (both and ipsilateral right lung, heart, and liver) for both CT data sets of each patient, were delineated. Single isocenter 3D-conformal RT plans were then formulated using the prescription dose as prescribed by their respective radiation oncologist, which ranges from 50 to 50.4 Gy given in 25-28 fractions over 5 to 6 weeks with or without a boost to the surgical scar and high-risk regional nodes. This was followed by the generation of dose-volume histograms (DVHs). From these DVHs, the volume receiving at least 95% (V95%) of the prescribed dose and the volume receiving at least 90% (V90%) for the target volume; the mean dose, volume receiving at least 10 Gy (V10Gy) and at least 20 Gy (V20Gy) for the liver; the mean dose and the volume receiving at least 5Gy (V5Gy) for the heart; the mean dose as well as the V20Gy of both and ipsilateral right lung; and the total and ipsilateral right lung volume for both the DIBH and FB RT plans of each patient were then recorded and were statistically compared.
Results
From the data gathered, this study showed a significant reduction in total lung mean V20 Gy, as well as all liver dose-volume parameters (mean dose, mean V10Gy, and mean V20Gy) for the DIBH RT plans compared to the FB RT plans. However, for the heart, a significantly higher mean dose, as well as mean V5Gy, has been noted for the DIBH RT plans. Despite this increase in cardiac exposure, the dose received by the heart is only minimal because our patients have a right-sided disease.
Conclusion
This study supports the use of the DIBH technique in right-sided breast cancer patients especially those undergoing post-operative locoregional radiotherapy.