Comparison of virtual and titanium clip marking of tumour resection margins for improved radiation planning in head and neck cancer surgery.

Communication between the surgeon and the radiation oncologist is improved with the use of virtual models of the final tumour resection, combining three-dimensional imaging and conventional clip marking with computer-aided navigation. This investigation was designed to determine the deviation of virtual marking procedures compared to conventional marking by titanium ligature clips in oral cancer with different localizations. Seventeen patients with surgically placed clips and virtual landmarks on the resection margin after complete tumour ablation were evaluated. To determine whether the virtual landmarks remain predictive of the resection margin, the deviation of the virtual points from their corresponding clips was analyzed by measuring the distance between their centres of gravity. In total, 189 clips were evaluated. Metric analyses of the deviation between the virtual points and clips showed a deviation of 2.3 ± 0.6mm for tumours with a maxilla localization, 7.2 ± 2.5mm for tumours with a mandible localization, and 12.6 ± 3.8mm for tumours with a tongue localization. A significant statistical relationship was demonstrated in the virtual point-clip deviation as a function of tumour localization. Virtual marking of maxillary tumour resection margins allows accurate definition of the former tumour bed and could lead to novel adjuvant treatment strategies.