AUTOMATED CALIBRATION ADJUSTMENT FOR FILM DOSIMETRY

摘要

The present invention provides a method of correcting errors in film dosimet ry measurements arising from variations in radiographic film processing and manufacturing. The method includes: (1) irradiating separate and distinct areas of one or more calibration films with different radiation dose levels to obtain a first calibration; (2) exposing a non-irradiated portion of at leas t one (and typically all) of the calibration films to light from an array of standardized light sources to obtain a first optical density step gradient; (3) exposing a non-irradiated portion of subsequent test films to light from the array of standardized light sources to obtain a second optical density step gradient; and (4) modifying the first calibration or optical density values of the test films based on differences between the first and second optical density step gradients. Since the characteristics of each of the standardized light sources vary little from one exposure to the next, any deviations in the optical density step gradient among different films result s, presumably, from changes in film processing or differences in film chemistry .