ABSTRACT
Objective:A new algorithm based on Hough transform (HT) was proposed to improve the accuracy and stability of the film image analysis of Automatic Quality Assurance (AQA) test, and to explore the influence of the resolution of film image on the test results.Methods:Nine pairs of films were obtained for AQA modules in this study. Firstly, the median filter was used to preprocess the grayed-out film image to remove noise interference. Then, a global threshold was utilized to binarize the image. The images were edge-detected and the film edge line was extracted by Hough transform. The film image was transformed to the correct position. Finally, the edge of the field shadow circle and the shadow circle of the tungsten ball were extracted by the edge detection method and Hough transform. The radial error was finally obtained by analyzing the concentricity.Results:There was no significant difference in the accuracy between the test results yielded by the HT method and the AQA software ( P>0.05). The difference in the standard deviation of the test results was statistically significant ( P=0.027), indicating that the algorithm increased the stability while ensuring the accuracy of film analysis. Increasing the resolution of film scanning failed to significantly improve the accuracy and stability of film analysis in both two methods. Conclusions:The algorithm used in this study can eliminate the human error caused by film scanning placement while ensuring the accuracy of film analysis, providing a more stable way for the AQA test of the CyberKnife system.
ABSTRACT
Objective To investigate the effect of taking medical students as standardized patients(SSP) on problem based leaming(PBL) teaching in clerkship.Methods Totally 161 students (grade 2008) selected from clinical medical department was divided into PBL group(n=81) and lecture-based learning(LBL) group(n=80).SSP was introduced into PBL teaching and LBL group was taught by LBL.After the clerkship,theory test was conducted in two groups and questionnaire was given to LBL group.Statistical analyses were conducted by SPSS 13.0,measurement data were analyzed by t test and enumeration data were described by frequency and constituent ratio.Results Theory test results showed that the average score of medical record analysis was (37.35 ± 5.95) in PBL group,much higher than (33.25 ± 4.89) in LBL group(P=0.001) ;the total score was (71.20 ± 8.67) in PBL group,much higher than that of (67.79 ± 9.87) in LBL group(P=0.018) as well.The average scores of choice question in 2 groups were (33.85 ± 5.05) and (34.24 ± 6.87),without significant differences(P=0.658).The constituent ratio of answer ‘OK' regarding 10 entries in questionnaire was more than 75％.The constituent ratio of answer ‘OK' regarding 3 entries(SSP matching degree,SSP without implied language or action,stimulating the learning interest) was more than 90％.Conclusions Introducing SSP PBL teaching can improve students' ability of clinical analysis and problem solving but not so effective for the basic theoretical knowledge grasp.SSP could replace standardized patients in PBL teaching.