Verification of plaque simulator dose distributions using GAFCHROMIC EBT film

OBJECTIVES: Off-axis dose profile and central-axis dose distributions were measured using GAFCHROMIC EBT film and calculated using BEBIG plaque simulator for COMS plaques of 14, 16, 18 and 20 mm diameter fully loaded with I-125 seeds. Results were compared to verify dose distribution as calculated by BEBIG. METHODS: Measurements were made on polystyrene eye phantom placed in a wax head phantom. RESULTS: The results of GAFCHROMIC EBT film were 13% lower than the results using BEBIG plaque simulator. This can be attributed to the facts that the model eye does not reflect the human eye exactly and that our measurement devices are inadequate. CONCLUSION: The BEBIG treatment planning computer can be used considering the shortcomings with respect to the first few mm and remote off-axis points. Furthermore, dose verification in patients can be made using GAFCHROMIC EBT film on a model eye phantom.