Evaluation of an electronic portal imaging device for transit dosimetry.
The possibility of using a commercially available electronic portal imaging device for transit dosimetry was investigated. The detection unit of the device comprises a metal plate/fluorescence screen and a camera. Basic parameters of this system were investigated: stability, detector uniformity, dose-response curve, field-size dependence and phantom-thickness dependence. It was found that in terms of relative dosimetry, portal images corrected for detector non-uniformity are in good agreement (within 5%) with transit dose distributions measured by film dosimetry. For dose determination, it was found that the use of the device is hampered by an important field-size dependence and phantom-thickness dependence. Both correction factors should be applied if the device is to be used for this purpose.
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Department of Oncology, University Hospital Leuven, Belgium.
Van Esch
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Reymen
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Huyskens
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D
D015502:Absorptiometry, Photon; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D011786:Quality Control; D011878:Radiotherapy / Q000295:instrumentation* / Q000592:standards; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012680:Sensitivity and Specificity; D014962:X-Ray Film