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Dosimetric Characteristic of Zeiss IntraBeam Flat and Surface Applicators


Y Xu

Y Xu*, S Lam, Cancer Treatment Center of America, Goodyear, AZ

SU-E-T-348 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose:
To verify the dosimetric characteristics of Flat and Surface applicators (two of each, 2cm and 4cm in diameters) for Zeiss Intrabeam system

Methods:
Dose rate vs. distance from surface of the applicators were measured with the 1D water tank and PTW ion chamber provided by IntraBeam system. Gafchromic films and solid water were used to determine the 2D dose distribution and beam divergence of the applicators.

Results:
The highest dose rate is from 2cm Surface applicator (3.4Gy/min at 1.6mm from applicator surface, it drops to 0.52Gy/min at 10mm). The 2cm Flat applicator dose rate is 1.47Gy/min at 1.6mm; it drops to 0.36Gy/min at 10mm. The lowest dose rate is from the 4cm Flat applicator (0.49Gy/min at 1.6mm; it drops to 0.18Gy/min at 10mm). The 4cm Surface applicator dose rate is 1.36Gy/min at 1.6mm; it drops to 0.29Gy/min at 10mm. All the data were verified and confirmed with the manufacture factory measurements.
Two dimensional dose profiles (parallel to applicator surface) at different depths were plotted from scanned Gafchromic films. Dose divergence of approximately 85 degree for 4cm applicators; and 65 degree for 2cm applicators; can also be seen from exposed films perpendicular to the applicator surface.

Conclusion:
Dosimetric characteristic were studied for both Flat and Surface applicators from Intrabeam system. Although all the applicators in this study are still pending FDA approval for clinical use, the data collected thus far can serve as a framework for both radiation oncologists and medical physicists to build the future clinical trials and treatment programs.

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