Abstract
Purpose :
To present a new method using artifacts from ultrasonography B-scans to determine correct dose to apex of the tumor in patients treated with Ru-106 brachytherapy for intraocular tumors.
Methods :
273 eyes were included in the study and 245 (90 %) of these were evaluable. Tumor height and double dose depth were measured based on the mirror-image artifact associated with ultrasound. Distances from the plaque to the tumor base were calculated from these two measures. Minimum doses to apex of the tumor were determined using Plaque SimulatorTM.
Results :
Distances from the plaque to tumor base were distributed with mean μ=0.99 (median: 1, range: 0.1 mm – 2.9 mm). In a phantom simulation study it showed that an increase in scleral thickness from 0.3 mm to 1.7 mm resulted in minimum dose delivered to the apex of the tumor ranged from 130-70 Gy. Provided a fully adapted plaque, ultrasound could be used to determine dose depth, by exploiting the mirror-image artifact.
Conclusions :
We found that distances from the plaque to tumor base vary among patients. This distance must be accurately taken into account to ensure that the prescribed dose is delivered during Ru-106 treatments.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.