Gammatile Tile Estimate and Dose Evaluation
Abstract
Purpose
To discuss the challenges with estimating the number of GammaTiles to order and how to evaluate dose distribution.
Methods
Data was compiled retrospectively to analyze the number of GammaTiles ordered and if the PTV had 95% coverage by the 50% isodose line.
Results
14 patients had their data analyzed retrospectively. 6 patients had no leftover tiles after surgery. Of those 6 patients 2 did not have 95% coverage of their PTV by the 50% isodose line. Overall 11 of the 14 patients had their PTV 95% covered by the 50% isodose line. In total these 14 patients had 104 GammaTiles ordered, and we had 19 tiles that were not used.
Conclusion
8 of the 14 patients had at least one leftover GammaTile. The challenge becomes ordering enough GammaTiles for the surgeon to be able to completely line the cavity bed but not wasting resources with many leftover GammaTiles. When it comes to dose evaluation the challenge is not having an universally accepted method for defining the PTV. This makes it difficult to compare dose metrics across different sites. Overall we do a good job with only 2 of 14 patients not having 95% coverage of their PTV with no leftover GammaTiles. It should be noted that it is possible that the shape of the post resection cavity bed could be the cause of the dose coverage not reaching 95% by the 50% isodose line.