M Lafreniere*, J Cunha, M Descovich, C Park, N Prionas, M Sharma, UC San Francisco, San Francisco, CA

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  M Lafreniere

PO-GePV-M-195 (Sunday, 7/25/2021)   [Eastern Time (GMT-4)]

Purpose: Customized bolus is an important tool in modulating radiotherapy treatment planning in post-mastectomy (+/- reconstruction) patients. Three‐dimensional printing of boluses can streamline custom bolus fabrication in radiotherapy. We present guidelines for implementing a 3D printing program specifically tailored for the production of custom breast boluses in the context of a radiation oncology clinic.

Methods: We considered 10 different printers having a large enough footprint to produce breast boluses in one piece, and a fast-printing speed to allow timely clinical production of breast boluses. We selected the one with the fastest printing speed (Ultimaker S5) to conduct our evaluation. We compared cost, fabrication time, dosimetric properties and geometric accuracy of wax bolus versus 3D printed bolus. The absorbed dose was measured with OLSDs for 20 different bolus thicknesses and materials (wax, thermoplastic, PLA and TPU), and with a field size of 10 cm by 10 cm, 200 MUs at 6 MV, and 100 SAD.

Results: The conventional wax bolus fabrication method used at our institution takes about 5.5 hours. The 3D printed bolus fabrication process can save about 5 hours of work for each bolus made since about 30 minutes is required to supervise the 3D printing process. Moreover, custom bolus production cost can be cut down significantly once the 3D printer is purchased, since 1 kg of wax costs about $60, and 1 kg of PLA costs about $20. A layer height of 0.4 mm enables both sufficient thickness precision and efficient printing speed. Using 3D printing allow to decrease the bolus thickness uncertainty associated with the manual bolus fabrication process. There are no significant dosimetric differences between the wax boluses and the 3D printed boluses.

Conclusion: Our results show that 3D printing is an efficient, cost-effective and accurate method to produce breast boluses.

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Keywords

Dosimetry, Radiation Dosimetry, Surface Dose

Taxonomy

Not Applicable / None Entered.

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