Abstract: A method of estimating a radiation dose deposited on a radiochromic film based on absorption measurements at least at two wavelengths as well as devices implementing the estimation method. The method includes the following steps: (a) measuring absorption values at a first wavelength and a second wavelength; (b) converting the absorption values at the two wavelengths to dose values at the corresponding wavelengths by using a calibration procedure; (c) obtaining a weighting factor curve (weighting factor vs. dose) at each wavelengths; and (d) obtaining an estimate of irradiation dose at the location on the radiochromic film by minimizing the objective function which takes the weighting factors and the dose values at both wavelengths as input.

Abstract: Radiation dose deposited on a radiochromic film is considered as a dose image. A precise image extraction system with commensurate capabilities is required to measure the transmittance of the dose image and correlate it with radiation dose. The disclosed microdensitometer system is designed to achieve this goal according to the unique characteristics of the radiochromic films, namely (a) the linearity and sensitivity of the dose response of the radiochromic films being highly dependent on the wavelength of the analyzing light and (b) the inherently high spatial resolution of the radiocbromic films. The disclosed microdensitometer system consists of a monochromator which provides analyzing light of variable wavelength, a film holder on a high-precision scanning stage, a CCD-dedicated microscope in conjunction with a thermoelectrically cooled CCD camera, corresponding computer interfaces and a microcomputer.

Abstract: A microdensitometer system capable of micrometer resolution for reading radiochromic films, includes: a film holder for supporting a radio chromic film sample; a high-precision scanning stage including a monochromatic light source for illuminating the film sample; a CCD microscope camera for a photographing light from the light source that is transmitted through the film sample; and a microcomputer for analysing data relayed from the CCD microscope camera. The film sample is translated by the scanning stage to enable analysis of the whole film sample.

Abstract: A microdensitometer arranged to scan an exposed film is coupled to a programmed computer. The computer analyses images captured through a microscope by a digital camera and to ‘map’ and indicate the optical density of the exposed film and distribution of density levels at any visible wavelength. This information, recorded in the exposed film, can be used to determine the actual exposure to which a patient has been subjected during X-ray treatment, where the film has been exposed to the X-rays during the treatment. If a film is sensitive to mechanical stress, the microdensitometer can also be used to yield mechanical stress distribution that has been applied to the film.