A patient with laryngeal cancer is simulated for a matched midline neck field. The superior border reaches the skull base, and both shoulders must sit in a fixed, repeatable position clear of the lower border at every fraction. Which immobilization setup best reproduces this treatment position?
Select an answer to reveal the explanation.
Short Explanation
You’ll get the most reproducible position with a thermoplastic face-and-neck mask, indexed headrest, and shoulder pulls working together. The mask and headrest control your head position, while the pulls keep both shoulders consistently clear of the lower field border.
Full Explanation
A thermoplastic face-and-neck mask with an indexed headrest and shoulder pulls provides complementary control of the head, neck, and shoulders. The mask and indexed headrest help reproduce head position when the superior field reaches the skull base, while the pulls secure both shoulders in a consistent position clear of the lower field border. A mask with an indexed headrest but no shoulder pulls can stabilize the head, but does not reliably hold both shoulders in the required fixed position from fraction to fraction. Shoulder pulls that leave the shoulders in-field do not meet the specified clearance requirement, even if the position is repeatable. Shoulder pulls paired with a nonindexed headrest may control the shoulders, but the head support cannot be returned to the same indexed position each day, compromising reproducibility of the skull-base setup. Exam caveat: the device combination alone does not establish correct positioning; the field borders and immobilization must be considered together. Practical check: before treatment, verify the headrest index and mask fit, confirm both shoulders are pulled down symmetrically, and check that they remain clear of the lower border in the planned treatment position.