3D Extrusion Based Printing of Custom Bolus Using a Non-Invasive and Low Cost Method
T Fisher1*, M Bligh1, T Laurel1, K Rasmussen2, (1) Memorial Medical Center, Modesto, CA, (2) East Carolina Univ, Greenville, NCSU-E-T-328 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: To create precise patient specific bolus for an irregular surface using a non-invasive and low cost method of 3D printing.
Methods: An infrared camera (Microsoft Kinect) is used to obtain a 3D model patients' face in real-time (ReconstructMe). Image processing such as reorienting non-manifold surfaces, smoothing, and filling holes is performed to refine the model using freely available software (Meshlab, Netfab). The bolus was constructed by two methods using a 3D Acrylonitrile Butadiene Styrene (ABS) extrusion based printer. The 1st method used was to print out a 1:1 scale model of the patient's nose, and construct the bolus using wax on face model. The 2nd method used was to create a digital model of the bolus material to the specifications of the physician (depth, size). This bolus can either be printed solid, or with a low infill percentage and filled with wax to save print time.
Results: Average scan time to obtain face model is 5 minutes (+/-2 minutes). Image processing varies on model, around 30 minutes. Print time ranges from 1-4 hours. The physicist time requirement to manufacture bolus material is greatly reduced compared to producing a physical mold of patient's anatomy. Patient comfort is greatly increased. Both wax bolus and ABS bolus are highly conformal to patient's face. A CT is not necessary to create our bolus material, however a CT performed on the bolus alone demonstrated high HU homogeneity (HU range).
Startup costs range from $1000-$3000 dollars, depending on model and capabilities of the extruder. Typical material cost is around $3-$10 per patient depending on bolus volume.
Conclusion: Highly irregular surfaces can be digitally modeled with high precision. Patient specific bolus can be made quickly, inexpensively, and without complex imaging.