Rotational setup errors in pediatric stereotactic radiation therapy.

Area of Science:

• Pediatric Radiation Oncology
• Medical Physics
• Image-Guided Therapy

Background:

• Stereotactic radiation therapy (SRT) is increasingly utilized in pediatric oncology.
• Accurate patient positioning is crucial for effective SRT, often enhanced by image guidance.
• Robotic couches have limitations in correcting significant rotational setup errors, typically around 3 degrees.

Purpose of the Study:

• To evaluate the frequency and magnitude of rotational setup errors in pediatric brain tumor patients undergoing SRT.
• To compare rotational errors between younger children (<5 years) and older children (≥5 years).
• To analyze the influence of steroid use and temporal trends on rotational errors.

Main Methods:

• Retrospective review of rotational corrections for pediatric patients (≤21 years) treated between 2009 and 2011.
• Comparison of rotational errors between two age groups: <5 years and ≥5 years.
• Analysis of steroid use impact and error trends over the treatment period.

Main Results:

• Younger children (<5 years) exhibited larger mean pitch corrections and greater variance in pitch, roll, and yaw errors compared to older children.
• Rotational errors exceeding 3 degrees were more frequent in younger children (21.7% pitch, 10.6% roll, 20.9% yaw) than in older children (15.6% pitch, 2.1% roll, 13.8% yaw).
• Both age groups showed larger pitch and roll corrections in children treated with steroids.

Conclusions:

• Rotational setup errors in pediatric SRT are more common than previously reported, particularly in younger children and those on steroids.
• These errors may exceed the correction capabilities of current robotic systems, posing a challenge for treatment accuracy.
• Treatment planning and delivery processes have been modified to better address rotational errors in pediatric SRT.