ABSTRACT
In order to analyze the image noise effect on the results of Gamma knife dosimetry parameter test, we tested the dosimetry parameters of the Gamma knives according to GBZ 168-2005. Radiological protection standards of X (gamma)-ray stereotactic radiosurgery for head treatment. Dose analysis software was applied to examine the testing film before and after image denoising, and SPSS 11.0 software was used for statistical analysis. The results showed that there was a significant difference in the results of the maximum deviation between radiation field size and its nominal value (t = 7.600, P < 0.01) and the radiation field's penumbra region width of collimators also had significantly different sizes (t = 5.334, P < 0.01) before and after image denoising. This study indicated that the image noise could influence the results of testing Gamma knife dosimetry parameters, so as to cause deviations.
Subject(s)
Humans , Algorithms , Artifacts , Gamma Rays , Head , General Surgery , Radiometry , Radiosurgery , Radiotherapy Planning, Computer-Assisted , Methods , Stereotaxic TechniquesABSTRACT
Objective To compare the analytical result of different kinds of film dose analysis software for the same gamma knife,analyze the reasons of difference caused,and explore the measurements and means for quality control and quality assurance during testing gamma knife and analyzing its result.Methods To test the Moon Deity gamma knife with Kodak EDR2 film and γ-Star gamma knife with GAFCHROMIC(R) EBT film,respectively.All the validation films are scanned to proper imagine format for dose analysis software by EPSON PERFECTION V750 PRO scanner.Then imagines of Moon Deity gamma knife are analyzed with Robot Knife Adjuvant 1.09 and Fas-09 1.0,and imagines of γ-Star gamma knife with Fas-09 and MATLAB 7.0.Results There is no significant difference in the maximum deviation of radiation field size ( Full Width at Half Maximum,FWHM) and its nominal value between Robot Knife Adjuvant and Fas-09 for Moon Deity gamma knife (t = -2.133,P ＞0.05).The analysis on the radiation field' s penumbra region width of collimators which have different sizes indicated that the differences are significant (t = - 8.154,P ＜ 0.05 ).There is no significant difference in the maximum deviation of FWHM and its nominal value between Fas-09 and MATLAB for γ-Star gamma knife ( t = - 1.384,P ＞0.05 ).However,following national standards,analysis of φ4 mm width of collimators can obtain different results according to the two kinds software,and the result of Fas-09 is not qualified while MATLAB is qualified.The analysis on the radiation field' s penumbra region width of collimators which have different sizes indicates that the differences are significant ( t = 3.074,P ＜ 0.05 ).The imagines are processed with Fas-09.The analysis of imagine in the pre-and the post-processing indicates that there is no significant difference in the maximum deviation of FWHM and its nominal value ( t = 0.647,P ＞ 0.05 ),and the analytical result of the radiation field' s penumbra region width indicates that there is no significant difference as well ( t = -0.627,P ＞ 0.05 ).Conclusion The study shows that different kinds of film dose analysis software may have some differences in analysis of the same gamma knife validation film,and the results may lead to the different decisions in accordance with national standard.
ABSTRACT
BACKGROUND: Undergraduates from military medical universities face many psychological stresses. Poor coping style might affect the status of mental health. Mental health might also be associated with social support and personality.OBJECTIVE: To investigate the correlation of social support and coping style with mental health among undergraduates from military medical universities.DESIGN: Cluster sampling and questionnaire investigation.SETTING: The Center of Basic Medicine Eexperiment, School of Basic Medicine and School of Preventive Medicine of Fourth Military Medical University of Chinese PLA, and Xi'an Hospital of Sports Trauma.PARTICIPANTS: Totally 352 freshmen of a military medical university were chosen by cluster sampling in October 2004 as the subjects.METHODS: Investigationwas performed on subjects with Symptom checklist-90 (SCL-90), social support rating scale (SSRS), coping style questionnaire (CSQ) and revised Eysenck's personality questionnaires short scale for Chinese (EPQ-RSC).SCL-90 consists of 90 items, including 10 factors. SSRS consists of subjective support, objective support and the utilization of support 3 factors as well as total score of social support. CSQ consists of problem solving, self-reproach, asking for help, keeping out of the way, fancy, rationalization 6 factors. EPQ-RSC mainly consisted of extraversion-introversion (E), neuroticism (N), psychoticism/tough mindedness (P) and lie/social diserability (L) 4 dimensions. Data were performed statistical management with t test and correlation analysis.MAIN OUTCOME MEASURES: ①Comparison of the scores of various factors of social support, coping style and personality among undergraduates with different mental health levels from military medical universities. ② Correlation of different social supports, copying styles and personalities with SCL-90. ③ Comparison of scores of mental health,coping style and personality of military medical undergraduates under different social supports.RESULTS: Totally 352 questionnaires were handed out and all of them were retrieved and eligible, with responding rate of 100%. ① The total scores of SRSS were taken as the grouping index, and 25% of the undergraduates who had the highest scores and the lowest scores were respectively chosen as severe symptom group and mild symptom group.Total scores of social support, subjective support and the utilization of support were higher in the mild symptom group than in the severe symptom group, but no difference in the objective support existed between two groups; Compared with mild symptom group, self-reproach, fancy, keeping out of the way and other immature coping styles were more significantly used, but asking for help was less, the scores of E were lower, but those of N were higher in the severe symptom group. ② Various factors of mental health were significantly negatively correlated with the total scores of support, the utilization of support, asking for help, E and L (r=-0.131 to -0.306 ,P ＜ 0.05 or P ＜ 0.01 ), but positively correlated with self-reproach,fancy, keeping out of the way, rationalization and N (r=0.141-0.450, P＜ 0.05 or P ＜ 0.01). ③ Total scores of support was used as the grouping index, 27% of the subjects who had the highest scores and lowest scores were chosen respectively as high support group and low support group.Mental health level was superior in the high support group to in the low support group; Most of the undergraduates of high support group preferred active coping styles, and those of low support group preferred passive coping styles; Scores of E of high support group were higher than those of low support group, and the scores of N and P were lower than those of low support group (P ＜ 0.05).CONCLUSION: Social support, coping style and EPQ-RSC interact and co-influence mental health.
ABSTRACT
Digitally reconstructed radiographs (DRR) which greatly contribute to the quality control of radiotherapy are critical element in the process of virtual simulation in radiotherapy. In this paper, an algorithm based on ray tracing has been used to generate the DRR. By applying an exponential transformation to the electronic density determined by CT value, the generated DRR can be enhanced by adjusting the attenuation and the transformation parameter.