Assessment of IGRT variability for lung SBRT

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• Variability in pre-treatment kilovoltage cone beam computed tomography (kV CBCT) image matching can impact the accuracy of lung stereotactic body radiation therapy (SBRT).
• Assessing factors contributing to inter-user variability is crucial for standardizing image-guided radiotherapy protocols.

Purpose of the Study:

• To evaluate factors influencing variability in kV CBCT image matching for lung SBRT.
• To determine if image origin, user institution, profession, experience, or image quality affect matching consistency.

Main Methods:

• Anonymized pre-treatment kV CBCT and planning CT datasets from lung SBRT patients were collected from four Alberta radiotherapy centers.
• Eight radiation therapists (RTTs) and four radiation oncologists (ROs) performed image matching on identical, randomized datasets.
• Inter-user variability was analyzed based on image origin, user institution, profession, experience, and image quality.

Main Results:

• Minimal inter-user variability was observed, with mean differences from consensus less than 1 mm.
• Clinically significant differences (>3 mm) were rare.
• Factors such as image origin, user institution, profession, image quality, and years of experience did not introduce meaningful clinical differences.

Conclusions:

• A high degree of standardization exists in the kV CBCT image matching process for lung SBRT across Alberta.
• The consistency between RTTs and ROs suggests RTTs may not require systematic RO approval for lung CBCT matches.
• Comprehensive training in CBCT image matching contributes to the observed consistency.