Study Protocol to Quantify Breast-Chest Wall Motion in Free Breathing, Version 5.1

Abstract

Background: Four-dimensional computed tomography (4D-CT) acquires multiple CT images over time, allowing to visualize the respiratory motion of organs and tumors. In patients undergoing 4D-CT for stereotactic radiotherapy of intra-thoracic tumors, 4D-CT provides the opportunity to study the incidental movements of the breast during normal breathing. A study protocol to investigate breast respiratory motion is presented herein. Methods: Patients with any primary cancer who underwent 4D-CT will be retrospectively selected from a radiotherapy treatment planning database. Study inclusion requires full lungs and breasts coverage in the 4D-CT images. Patients with advanced tumors are excluded. The protocol details breast locations of interest (upper, lower, inner, outer, central), specifies virtual breast tumor beds, and details how breast motion will be measured. Data will be analyzed to quantify the range of movements, to evaluate breast motion according to laterality and location, and to evaluate the correlation between movements of the breast and the intra-thoracic organs. Results: Results should provide quantitative information on the extent of breast movements during free breathing, which could be valuable to plan for respiratory control during breast radiotherapy. Conclusion: The study is retrospective, but the design of data acquisition is prospective, to mitigate recollection bias and enhance reproducibility.