This paper studies the technics of reducing item exposure by utilizing automatic item generation methods. Known test item calibration method uses item parameter estimation with the statistical data, collected during e...This paper studies the technics of reducing item exposure by utilizing automatic item generation methods. Known test item calibration method uses item parameter estimation with the statistical data, collected during examinees prior testing. Disadvantage of the mentioned item calibration method is the item exposure; when test items become familiar to the examinees. To reduce the item exposure, automatic item generation method is used, where item models are being constructed based on already calibrated test items without losing already estimated item parameters. A technic of item model extraction method from the already calibrated and therefore exposed test items described, which can be used by the test item development specialists to integrate automatic item generation principles with the existing testing applications.展开更多
Objective: To study the effective computerized image processing of underexposed and overexposed X-rays of bones and joints. Methods: Ninety-nine conventional X-ray images (82 were overexposed and 17 were underexposed)...Objective: To study the effective computerized image processing of underexposed and overexposed X-rays of bones and joints. Methods: Ninety-nine conventional X-ray images (82 were overexposed and 17 were underexposed),scanned by an UMAX Astra 4000U Scanner, were converted into digital images on the basis of their analog images. A computerized imaging processing program consisting of five functional modules such as Contrast Stretch, Fast Flourier Transform (FFT), Image Smoothing Modules, Inverse Fast Flourier Transform (IFFT) and Nonlinear Transform performed image contrast stretch and smoothing. Three senior doctors from hospital image sections made their evaluation of all the processed images. Results: Of 82 overexposed films, 71 met the clinical requirements after image processing, and 11 were unable to be applied to clinical diagnosis, accounting for 87% and 13% respectively. Of the other 17 underexposed X-ray images, 11 met the clinical requirements while 6 were not, making a percentage of 64 and 35. Conclusion: Image contrast stretch and smoothing processing are significantly effective on conventional X-ray images which were inappropriately exposed, and can avoid more X-ray radiation caused by handling of radiological photograph again. This method can decrease hospital cost and provide acute and effective X-ray examinations for the treatment and cure for critical patients.展开更多
文摘This paper studies the technics of reducing item exposure by utilizing automatic item generation methods. Known test item calibration method uses item parameter estimation with the statistical data, collected during examinees prior testing. Disadvantage of the mentioned item calibration method is the item exposure; when test items become familiar to the examinees. To reduce the item exposure, automatic item generation method is used, where item models are being constructed based on already calibrated test items without losing already estimated item parameters. A technic of item model extraction method from the already calibrated and therefore exposed test items described, which can be used by the test item development specialists to integrate automatic item generation principles with the existing testing applications.
文摘Objective: To study the effective computerized image processing of underexposed and overexposed X-rays of bones and joints. Methods: Ninety-nine conventional X-ray images (82 were overexposed and 17 were underexposed),scanned by an UMAX Astra 4000U Scanner, were converted into digital images on the basis of their analog images. A computerized imaging processing program consisting of five functional modules such as Contrast Stretch, Fast Flourier Transform (FFT), Image Smoothing Modules, Inverse Fast Flourier Transform (IFFT) and Nonlinear Transform performed image contrast stretch and smoothing. Three senior doctors from hospital image sections made their evaluation of all the processed images. Results: Of 82 overexposed films, 71 met the clinical requirements after image processing, and 11 were unable to be applied to clinical diagnosis, accounting for 87% and 13% respectively. Of the other 17 underexposed X-ray images, 11 met the clinical requirements while 6 were not, making a percentage of 64 and 35. Conclusion: Image contrast stretch and smoothing processing are significantly effective on conventional X-ray images which were inappropriately exposed, and can avoid more X-ray radiation caused by handling of radiological photograph again. This method can decrease hospital cost and provide acute and effective X-ray examinations for the treatment and cure for critical patients.
