Technical Note: Dose distributions in the vicinity of high-density implants using 3D gel dosimeters.

PURPOSE: In this work, we develop a methodology for using Fricke gel dosimeters for dose distribution measurements surrounding high-density implants which circumvents artifact production by removing the obstruction during imaging.

METHODS: Custom 3D printed molds were used to set cavities in Fricke gel phantoms to allow for the suspension of high-density implants in different geometries. This allowed for the metal valve extracted from a temporary tissue expander to be suspended during irradiation, and removed during optical-CT scanning.

RESULTS: The removal of the metal implant and subsequent backfilling of the remaining cavity with optically matched fluid prior to dose evaluation enables accurate optical-CT scanning of the gel dosimeters. Results have shown very good agreement between measured and calculated doses within 2 mm from the surface of the implant. Slight deviations are present within 1 mm of the interface.

CONCLUSIONS: Artifacts in the form of radial streaking, cold spots, and hot spots were all reduced using this technique, enabling the broader and more accurate use of optical-CT for the imaging of gels containing opaque objects.