Development of a Reusable Universal Head Immobilization Method for Radiotherapy in Dogs.

Area of Science:

• Veterinary Radiation Oncology
• Medical Imaging
• Biomedical Engineering

Background:

• Reproducible immobilization is crucial for small animal radiotherapy, particularly for head treatments.
• Conventional methods often require patient-specific masks, increasing complexity and time.
• Assessing immobilization accuracy for bony landmarks, mandible, and lymph nodes in the head and neck is vital.

Purpose of the Study:

• To develop and evaluate a reusable, universal thermoplastic mask for small animal head immobilization.
• To compare the accuracy and efficiency of this universal method against conventional cylinder and patient-specific mask techniques.
• To assess positional errors in bony landmarks, mandible, and lymph nodes using repeated CT scans.

Main Methods:

• Development of a universal thermoplastic mask system using molded cylinders.
• Comparative study involving five beagle dogs undergoing CT scans with three immobilization methods: universal mask, cylinder, and patient-specific mask.
• Measurement of positional errors for anatomical landmarks including maxilla, mandible, and lymph nodes.

Main Results:

• The universal immobilization method demonstrated accuracy comparable to conventional techniques for bony landmarks.
• Universal immobilization showed superior performance over cylindrical immobilization for lymph node positioning.
• All tested head immobilization methods exhibited significant positional errors for lymph nodes.
• The universal method offered the shortest setup time, indicating high efficiency.

Conclusions:

• The reusable universal thermoplastic mask is a precise, efficient, and sustainable alternative for small animal head immobilization.
• While promising, further clinical validation is needed, as this study serves as a model investigation.
• Improvements in lymph node immobilization accuracy are necessary across all head immobilization techniques.