AbstractID: 8267 Title: Characterization of an inexpensive transmission color linear-
CCD array film digitizer for IMRT dosimetry
Intensity modulated radiation therapy (IMRT) delivery creates complex highgradient dose distributions built up from many small area beams. High resolution film dosimetry is often the only practical dosimetry technique for validating IMRT dose distributions. With IMRT, high-dose regions can be built out of the superposition of high gradient penumbra making for a wide variation in beam quality in regions of significant dose; raising concerns over the energy dependence of radiographic film dosimetry. Hence, the ability to perform both routine radiographic and benchmark radiochromic film dosimetry is desirable in a clinical film digitizer. Unfortunately, most fast high spatial-resolution film digitizers employed in ionizing radiation film dosimetry are not sufficiently characterized or have know artifacts preventing accurate high-gradient dose imaging. Careful characterization and artifact removal through image processing techniques have been shown to allow successful application of these devices to high-gradient film dosimetry. In this study, we investigate the characteristics an inexpensive 48-bit 1200 dpi color CCD film digitizer fitted with an antireflectivecoating scanning platen for use in IMRT film dosimetry. This film digitizer was validated using benchmark radiographic films printed on a laser film printer and intercomparison with a previously validated system. Remarkably, this inexpensive film scanner was found to be free of known interference and light scatter artifacts. Though it is limited to an effective OD range of 0.1 - 1.3 OD, it was found to accurately image high-gradient dose distributions exhibited by
IMRT using either radiographic (grayscale) or radiochromic (red CCD channel) film.