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利用数学形态学算法计算EBT3胶片拍摄的近距离治疗中放射源的位置准确性。目前验证192Ir放射源到位精度的方法主要包括胶片、Fricke放射量测定器、平板探测器、简单的直尺结合计量仪方法等,数学形态学算法自动计算曝光胶片放射源的位置未见报道。本研究用EBT3免冲洗胶片分别获得不同步进长度和已知驻留位置误差的影像。采用Contourlet变换对胶片图像进行去噪,求得放射源步进长度的误差小于±0.2 mm,源驻留位置的误差在±0.5 mm以内,符合临床要求。结果表明本方法简单,且结果可靠。
Using mathematical morphology algorithm to calculate the position accuracy of radioactive sources in brachytherapy of EBT3 film. At present, the methods to verify the accuracy of 192Ir radioactive sources include films, Fricke dosimeters, flat panel detectors, simple ruler combined with meter methods, and the mathematical morphology algorithm to automatically calculate the position of exposed film radioactive sources has not been reported. In this study, we used EBT3-free film to obtain the images with different step length and the known position error. Using Contourlet transform to denoise the film image, the error of the step length of the radioactive source is less than ± 0.2 mm and the error of the source dwelling position within ± 0.5 mm, which meets the clinical requirements. The results show that the method is simple and reliable.