Novel radiation dose calibration methods for Gafchromic film: Exploring Histogram Correlation and Linearisation

Radiotherapy requires quality assurance of patient radiation dose delivery. Gafchromic® radiochromic film is used as a dosimeter to validate these deliveries. This research explores Histogram Correlation as a calibration tool for Gafchromic® radiochromic film in verification of dose, for both magnitude and spatial distribution. This led to the development of a practical method for the use of Gafchromic® radiochromic film for use in Radiotherapy IMRT QA. The basis of this method is that a derived function of the scan data [(Blank/Exposed)-1] is directly proportional to the dose the film has been exposed to. This allows calibration by the definition of only one parameter, the constant of proportionality.