(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: To assess skin dose enhancements from a brass mesh compared to superflab bolus for clinically relevant breast treatment delivery techniques.
Methods: Three breast treatment plans were generated on CT scans of a chest phantom; tangential step-and-shoot 3D conformal (3DCRT), tangential sliding-window 3DCRT, and volumetric modulated arc therapy (VMAT) with two 180° arcs. Skin doses of all three plans were measured with Gafchromic EBT3 Films. Each plan was delivered six times, with both one and two layers of brass mesh, with superflab of 3mm, 5mm, and 10mm thickness, and without bolus. Doses were determined from film read with an Epson scanner using a calibration curve calculated using films from the same batch.
Results: The skin doses measured between 94% and 110% of the prescription (Rx) dose for all plans with bolus. Without bolus, skin dose measured between 55% and 67% of Rx dose. A single layer of brass mesh consistently resulted in a skin dose ranging from 94% to 99% of Rx dose. The skin dose associated with the brass mesh was comparable; though lower, to skin dose enhancement by 3mm superflab (100% -103%). Skin dose enhancement from 5mm superflab was consistently between 3mm and 10mm bolus. Two layers of brass mesh increased skin dose comparable to that with 10mm superflab, both bolus types increased skin dose to between 104% - 110% above Rx dose.
Conclusion: Our study of skin dose with a brass mesh and differing thickness superflab showed that a brass mesh has an equivalent thickness to 3mm superflab, for commonly used breast treatment delivery methods. Adding a second layer of brass mesh was equivalent to 10mm superflab. From our results, we conclude that one layer and two layer mesh brass could be accordingly utilized instead of 3mm and 10mm superflab when flexibility and conformity is needed.
Keywords
Breast, Tissue Equivalency, Dosimetry
Taxonomy
TH- External beam- photons: General (most aspects)
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