Gafchromic film in Radiotherapy

I am trying to use imageJ to analyze the gafchromic film. First, I calibrated my films by giving them different dose levels to obtain calibration curve based on optical density by imageJ. Now , I am trying to get isodose curves in the exposed films. Would you please tell me how I can do that?

Good day,

please study the ImageJ User Guide and especially Section 30.9.

Please think about the way you are measuring the film, either as a transparency or in reflection.

If there are remaining problems, then please post again here.