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

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• High-density implants in radiation therapy can cause imaging artifacts.
• Accurate dose distribution measurement is crucial for effective treatment planning.

Purpose of the Study:

• To develop a Fricke gel dosimetry method for dose distribution measurements around high-density implants.
• To circumvent artifact production during imaging by removing the obstruction.

Main Methods:

• Utilized custom 3D printed molds for Fricke gel phantoms with suspended high-density implants.
• Irradiated phantoms with implants in place, then removed implants before optical-CT scanning.
• Backfilled cavities with optically matched fluid for accurate dose evaluation.

Main Results:

• Achieved accurate optical-CT scanning of gel dosimeters after implant removal and cavity backfilling.
• Demonstrated very good agreement between measured and calculated doses within 2 mm of the implant surface.
• Observed slight deviations within 1 mm of the implant interface.

Conclusions:

• Reduced artifacts like radial streaking, cold spots, and hot spots.
• Enabled broader and more accurate use of optical-CT for imaging gels with opaque objects.
• This technique enhances the reliability of Fricke gel dosimetry in complex treatment scenarios.