ABSTRACT
Partial or complete resection of the maxilla during tumour surgery causes oronasal defects, leading to oral-maxillofacial dysfunction, for which the surgical obturator (SO) is an important treatment option. Traditional manufacturing of SOs is complex, time-consuming, and often results in inadequate fit and function. This technical note describes a novel digital workflow to design and manufacture a three-dimensional (3D)-printed hollow SO. Registered computed tomography and magnetic resonance imaging images are used for gross tumour delineation. The produced RTStruct set is exported as a stereolitography (STL) file and merged with a 3D model of the dental status. Based on these merged files, a personalized and hollow digital SO design is created, and 3D printed. Due to the proper fit of the prefabricated SO, a soft silicone lining material can be used during surgery to adapt the prosthesis to the oronasal defect, instead of putty materials that are not suitable for this purpose. An STL file of this final SO is created during surgery, based on a scan of the relined SO. The digital workflow results in a SO weight reduction, an increased fit, an up-to-date digital SO copy, and overall easier clinical handling.
Subject(s)
Computer-Aided Design , Maxillary Neoplasms/surgery , Palatal Obturators , Printing, Three-Dimensional , Prosthesis Design , Algorithms , Female , Humans , Imaging, Three-Dimensional , Magnetic Resonance Imaging , Middle Aged , Software , Tomography, X-Ray Computed , WorkflowABSTRACT
OBJECTIVE: To quantify the potential increase in tumour volume during the waiting time for radiotherapy in patients with oropharyngeal squamous cell carcinoma. DESIGN: Retrospective study. METHOD: The tumour volumes as assessed on the diagnostic CT scan and the planning CT scan were compared. Thirteen patients with oropharyngeal carcinoma were included in this study. Both their diagnostic CT scan (CT-1) and their planning CT scan (CT-2) were performed in the Utrecht university medical centre. Tumour volume was calculated by delineating the tumour on CT slices and multiplying the surface area by the inter-slice distance. Tumour volumes were delineated by three independent observers. Tumour growth during the waiting time was defined as the difference in tumour volume on CT-2 and CT-1, calculated as the average of three observations. RESULTS: The mean time between CT-1 and CT-2 was 33 days. The mean waiting period between the histopathological diagnosis and the start of radiotherapy was 56 days. Three groups could be distinguished: in one group the growth was less than 25% (n = 4), in one group the growth varied between 25 and 100% (n = 5), and in a third group there was growth of more than 100% (n = 4). Apart from this, in three cases the TNM stage had to be adjusted as a result of tumour progression. CONCLUSION: This study showed that the tumour volume increased by more than 50% during the waiting time for radiotherapy in 8 out of 13 patients with squamous cell carcinoma of the oropharynx.
