Breathing motion can affect the ability to accurately target lung tumors during imaging and delivery of radiotherapy. Having the patient hold their breath is a simple and effective strategy for limiting tumor motion. However, some patients cannot hold their breath reproducibly, hence the development of active breathing control to assist the patient in achieving a reproducible, stable breath hold.

At the same time as the development of active breathing control, image-guided radiotherapy became available to help directly target the tumor during treatment. Our lab developed a new concept by combining these two existing strategies: cone beam CT-based image guidance for target localization with active breathing control (machine-induced breath hold) for reducing the impact of respiration.

Comparison of active breath hold CBCT with free breathing CBCT, 4D CBCT, and diagnostic quality CT.

We developed technology to enable integration of the active breathing control system with imaging and delivery systems on a linear accelerator, and then explored the ability of this system to improve the accuracy of delivery in a clinical imaging study. This study resulted in a process and equipment that is now in routine clinical practice at VCU and elsewhere.

This project was funded by the National Institutes of Health, Award No. R01CA116249.