Development of a relative dosimetric system for calibration of ³²P eye applicators using radiochromic films

Beta irradiation after bare scleral surgery of primary pterygium is an effective and safe treatment, which reduces the risk of local recurrence. Obtaining the reference dose rate for a radioactive applicator consisting of a plate as a ³²P absorber, a steel window and a steel capsule. Relative dosimetry and dose profile were measured using two types of radiochromic films, HD-810 and EBT1, for the ³²P applicator and were compared with Monte Carlo simulation data. Dose uniformity in the ³²P applicator was obtained with radiochromic HD-810 film. Results: The measurement depth dose distribution data at distances up to 3.8 mm were compared with calculation data, and the values were not found to differ statistically. Depth dose distribution with a large dose gradient was determined and the dose rate data obtained 0.0053 ± 9.9% in unit of Gy/s.mCi at a 0.1 mm depth distance. Practical results indicated that the dose nonuniformity and the maximum symmetrical for the ³²P applicator were 11.5% and 9.2%, respectively. Our experiments show that the use of the radiochromic film to perform the relative dosimetric checks is feasible and the activity value with acceptable error can be determined through this indirect method. (author)