(Saturday, 4/7/2018) 10:30 AM - 12:30 PM
Room: Marquis Ballroom 5-8
Purpose: Total Scalp Irradiation (TSI) requires the use of bolus to achieve adequate dose to the surface. Our current standard-of-care technique makes a bolus cap by taping together sheets of commercial bolus material formed to the patient’s head. This method is laborious, and ultimately produces a bolus cap that is difficult to reproduce and has limited conformality, leading to air gaps between the bolus and scalp. 3D-printing offers a minimally labor-intensive solution to create conformal patient-specific bolus. The purpose of this study was to develop a clinical workflow to 3D-print patient-specific bolus caps for TSI.
Methods: Two python scripts were developed to automate the creation of a ready to print 3D model for a patient-specific bolus cap from diagnostic CT scans. Several 3D printing materials were evaluated for use as a scalp bolus considering radiological tissue equivalency and material flexibility for patient comfort. A bolus cap model was generated for an anthropomorphic head phantom and 3D-printed using two different materials and printers. We acquired CT scans of the head phantom with the bolus caps and created VMAT TSI treatment plans for each data set.
Results: Two materials were identified to be suitable for use in a bolus cap: one that can be printed in-house, and the other by an external company. The time required to generate a patient-specific bolus model utilizing the scripts developed for our treatment planning system is less than 15 minutes. Review of the CT scans showed the bolus caps to be highly conformal, with maximum air gaps of 4 mm. VMAT treatment plans generated for these two bolus caps met our clinical dosimetric criteria.
Conclusion: We developed a workflow to produce highly conformal bolus caps and reduce the labor-intensive fabrication time. Future work will include dose verification measurements and cost analysis for in-house verses outsourced fabrication.
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