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Goodbye face masks! Accurate head and neck radiotherapy using individual dorsal shells and surface guidance
Marion Essers1, Lennart Mesch1, Maaike Beugeling1
1Institute Verbeeten, Radiation Oncology, PO Box 90120, 5000 LA Tilburg, the Netherlands.
Background And Purpose:
Using surface guided radiotherapy (SGRT), head and neck (H&N) cancer patients may undergo radiotherapy without the discomfort and stress of a restricting face mask. In this study, the patient setup accuracy, number of necessary treatment interrupts, and intrafraction motion for H&N cancer patients positioned using an individual dorsal shell and monitored using SGRT was examined.
Material And Methods:
Twenty-six H&N cancer patients were positioned in a dorsal shell using SGRT. A cone-beam CT (CBCT) was used for online setup correction. SGRT was also used for intrafraction motion monitoring, and repositioning of the patient when an intrafraction motion threshold of 2 mm or 2° (th2) was exceeded. Based on post-treatment CBCT's, the intrafraction motion and resulting CTV-PTV margin were determined.
Results:
For 1.1 % of fractions, the patient had to be repositioned because of motion during/after the CBCT, and for 4.4 % of fractions because of inaccurate patient posture. For 3.5 % of fractions, treatment had to be interrupted for repositioning because intrafraction motion exceeded th2. The CTV-PTV margin for intrafraction motion is 1.1 mm in all directions. A total CTV-PTV margin of 3 mm can be applied.
Conclusions:
By replacing traditional face masks with SGRT and a dorsal shell, we can offer H&N cancer patients a more comfortable radiotherapy treatment experience without sacrificing the treatment accuracy.
