Standardization of head and neck contouring using the acanthiomeatal line

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiological Imaging

Background:

• Accurate patient positioning is crucial for effective radiotherapy.
• Variability in chin positioning for head-and-neck cancer treatment can impact treatment planning and delivery.
• Standardization of positioning protocols is needed to improve consistency and reproducibility.

Purpose of the Study:

• To assess perceived versus actual chin positions used in head-and-neck cancer radiotherapy.
• To evaluate the consistency of chin positioning across different clinical settings.
• To identify methods for standardizing chin positioning for improved treatment planning.

Main Methods:

• Dosimetrists described external landmarks for chin positioning.
• Analysis of lateral treatment planning radiographic figures from a radiotherapy textbook.
• Physicians rated chin positions (mildly flexed, neutral, mildly extended, hyperextended) at 7 departments.
• Review of representative patient simulations for routine chin position.

Main Results:

• Dosimetrists used the acanthion and external auditory canals to set a neutral chin position.
• 82% of textbook figures depicted neutral chin positioning.
• 71.4% of radiotherapists believed patients were treated in hyperextended positions, but 85.7% of simulations showed neutral positioning.
• The acanthiomeatal line can achieve reproducible chin positioning.

Conclusions:

• A significant discrepancy exists between perceived and actual chin positions in head-and-neck cancer radiotherapy.
• The acanthiomeatal line provides a reliable method for standardizing chin positioning.
• Standardized chin positioning enhances the consistency of axial imaging, simplifying contouring and aiding in the development of treatment atlases and automated contouring tools.