Breathing adapted radiotherapy: a 4D gating software for lung cancer

Area of Science:

• Medical Imaging
• Radiation Oncology
• Pulmonary Medicine

Background:

• Physiological respiratory motion in lung tumors complicates radiotherapy (RT).
• Respiratory gating is a technique used to mitigate motion artifacts during RT.
• Accurate identification of the optimal respiratory phase is crucial for effective gated RT.

Purpose of the Study:

• To evaluate a novel 4D image processing software, the Respiratory Phase Optimizer (RPO).
• To determine the optimal respiratory phase for beam-on in lung cancer patients undergoing RT.
• To assess the utility of RPO in selecting patients who may benefit from breathing-adapted RT.

Main Methods:

• Fourteen lung cancer patients underwent 4D-CT scans capturing ten respiratory phases.
• Morphological parameters (tumor-to-lung volume ratio, tumor-to-spinal cord distance) were analyzed.
• RPO software automated calculations to identify the optimal respiratory phase for RT.

Main Results:

• Tumor motion varied, with lower lobe tumors not attached to the diaphragm showing the most significant movement.
• Maximum inspiration was optimal for 28.6% of patients.
• RPO identified optimal phases other than maximum inspiration in 50% of patients, demonstrating its value beyond simple gating.

Conclusions:

• RPO software effectively identifies optimal respiratory phases for gated RT using morphological parameters.
• The software is user-friendly and suitable for daily clinical routine.
• RPO can aid in patient selection for breathing-adapted radiotherapy, potentially improving treatment outcomes.