Program Information
Dosimetric Verification of a Ru-106 Eye Plaque
J Aubry*, E Mitrou , S Lassalle , N Cote , Centre hospitalier de l'Universite de Montreal, Montreal, QC
Presentations
TU-L-GePD-T-5 (Tuesday, August 1, 2017) 1:15 PM - 1:45 PM Room: Therapy ePoster Lounge
Purpose: To perform a dosimetric verification of a Ru-106 eye plaque using radiochromic films (EBT3).
Methods: The radioactive eye plaque used for this study was an Eckert & Ziegler type CCB, with a diameter of 20mm. Plastic phantoms were designed to hold a plaque with its concave side up, with the top of the phantom either even with the plaque rim, or even with the plaque eyelets used for suturing. The cavity can either be filled with water or left in ambient air. In water, a 3x3 cm2 film covered by a single layer of cellophane is placed on the phantom surface with 8mm of plastic water miniature slabs for backscatter. In air, a similar film is placed on the phantom surface without backscatter material. Films were exposed to obtain a dose at the center between 1 and 2 Gy. Dose profiles were also obtained from the Plaque Simulator software for comparison.
Results: Two measurements in air showed good reproducibility. Three dose measurements in water at a distance of 4.7mm of the plaque inner center and two at a distance of 7.5mm were performed. The absolute dose measured at the center of the plaque was compared to the absolute calculated dose based on dosimetric data provided by the manufacturer. At a depth of 4.7mm the difference between measured and calculated dose was -11.4%, and at 7.5mm the difference was 1.1%, which are both within the uncertainty reported by the manufacturer.
Conclusion: The absolute dose rate provided by the manufacturer could be independently checked at two depths using radiochromic films. Radial profiles obtained from the Plaque Simulator were also within reasonable agreement with those obtained from the radiochromic films. Measurements in air showed that the plaque radioactive integrity can be easily verified as a periodic constancy check.
Contact Email: