A standardized workflow for respiratory-gated motion management decision-making.

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• Motion management in lung and gastrointestinal stereotactic body radiotherapy (SBRT) is complex, requiring a balance between tissue sparing and target accuracy.
• Four-dimensional computed tomography (4DCT) analysis is crucial for optimizing respiratory gating parameters.
• Physicists play a key role in interpreting 4DCT data to guide treatment planning.

Purpose of the Study:

• To develop a standardized procedure for recommending respiratory gating parameters and planning margins for lung and gastrointestinal SBRT.
• To simplify decision-making and analysis for physicists managing tumor motion.
• To provide a tool for troubleshooting complex cases in respiratory-gated SBRT.

Main Methods:

• Identified key factors influencing gating decisions and planning target volume (PTV) margins.
• Defined gating options: exhale gating (50% duty cycle), reduced duty cycle exhale gating, and near-continuous treatment.
• Developed a standard operating procedure and physics consult document for clinical implementation.

Main Results:

• Factors influencing motion management include motion magnitude, breathing regularity, 4DCT quality, and target visibility on fluoroscopy.
• Created specific decision tables for lung and gastrointestinal tumors to guide optimal gating and PTV margin selection.
• The procedure was clinically implemented for 252 sites in 213 patients, standardizing practice across a 12-member physics team.

Conclusions:

• Implementing a standardized procedure for respiratory gating positively impacted clinical practice.
• The procedure improved the efficiency and ease of 4DCT analysis.
• Standardized gating decision-making among physicists, enhancing consistency in SBRT treatments.