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To investigate the γ pass rate limit of plan verification equipment for volumetric modulated arc therapy (VMAT) plan verification and its sensitivity on the opening and closing errors of multi-leaf collimator (MLC), 50 cases of nasopharyngeal carcinoma VMAT plan with clockwise and counterclockwise full arcs were randomly selected. Eight kinds of MLC opening and closing errors were introduced in 10 cases of them, and 80 plans with errors were generated. Firstly, the plan verification was conducted in the form of field-by-field measurement and true composite measurement. The γ analysis with the criteria of 3% dose difference, distance to agreement of 2 mm, 10% dose threshold, and absolute dose global normalized conditions were performed for these fields. Then gradient analysis was used to investigate the sensitivity of field-by-field measurement and true composite measurement on MLC opening and closing errors, and the receiver operating characteristic curve (ROC) was used to investigate the optimal threshold of γ pass rate for identifying errors. Tolerance limits and action limits for γ pass rates were calculated using statistical process control (SPC) method for another 40 cases. The error identification ability using the tolerance limit calculated by SPC method and the universal tolerance limit (95%) were compared with using the optimal threshold of ROC. The results show that for the true composite measurement, the clockwise arc and the counterclockwise arc, the descent gradients of the γ passing rate with per millimeter MLC opening error are 10.61%, 7.62% and 6.66%, respectively, and the descent gradients with per millimeter MLC closing error are 9.75%, 7.36% and 6.37%, respectively. The optimal thresholds obtained by the ROC method are 99.35%, 97.95% and 98.25%, respectively, and the tolerance limits obtained by the SPC method are 98.98%, 97.74% and 98.62%, respectively. The tolerance limit calculated by SPC method is close to the optimal threshold of ROC, both of which could identify all errors of ±2 mm, while the universal tolerance limit can only partially identify them, indicating that the universal tolerance limit is not sensitive on some large errors. Therefore, considering the factors such as ease of use and accuracy, it is suggested to use the true composite measurement in clinical practice, and to formulate tolerance limits and action limits suitable for the actual process of the institution based on the SPC method. In conclusion, it is expected that the results of this study can provide some references for institutions to optimize the radiotherapy plan verification process, set appropriate pass rate limit, and promote the standardization of plan verification.
Subject(s)
Humans , Radiotherapy, Intensity-Modulated , Immune Tolerance , Nasopharyngeal Carcinoma , ROC Curve , Nasopharyngeal Neoplasms/radiotherapyABSTRACT
Aim To establish a method for determining the antithrombotic biological activity of Honghua injection, which can be used to evaluate and control its quality. Methods Collagen-adrenalin was used to induce mouse acute cerebral thrombosis model and hemiplegic protection rate of Honghua injection in mice as an index to investigate the antithrombotic activity of Honghua injection. The experimental conditions of the administration dosage, inducer dosage, and different strains of mice were investigated, and the experimental conditions were optimized by orthogonal design. Results Honghua injection which was made by 5. 0 g crude drug · kg-1and continuously ip for 3 d, had obvious protective effect on collagen-adrenalin-induced acute cerebral thrombosis in mice. The established biological activity limit method showed a good repeatability, intermediate precision, and reproducibility. Each sample showed different degrees of differences in biological activity. Conclusions The thrombus test in mice can be used as a method for measuring the biological activity of Honghua injection. It is recommended to use 5. 0 g crude drug · kg-1dose as the limit for bioactive process optimization and product quality controlment of Honghua injection.
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A novel immunochromatographic assay was developed, which could provide visual evidence of triazophos in agro products, and also could directly identify the safety status by setting visual cut-off limit of detection in maximal residual limit ( MRL) value. Three test lines ( T1, T2, T3) were applied to the nitrocellulose membrane with different concentrations of Triazophos-OVA, and one control line (C) was settled with goat anti mouse IgG antibody. Thereafter, by combining with conjugate pad which immobilized monoclonal antibody labeled with 20 nm Colloidal gold particles, absorbent pad and PVC plate, a chromatographic test strip was assembled. With optimization of sample extraction and solvents selection, the test strips were employed for the determination of triazophos in rice, cabbage and apple. The results revealed that the cut-off limit of detection could reach 0. 005, 0. 01 and 0. 02 μg / mL represented by test line T3, T2 and T1, respectively. After modification, the cut-off limit of detection was resettled to 0. 05, 0. 1 and 0. 2 μg / mL according to the MRL values which enforced by the national standard of GB2763. Using acetonitrile for the sample extraction, the extracts were diluted 10 times or solvent exchanged with equivalent volume by PBS solution, and then tested by strips descripted above mentioned. The two test strips could precisely identified the safety status of agro product with MRL as threshold within 8-12 min. Furthermore, the residues value of triazophos could be quantified by the multiple quantitative test lines. Parallel GC data indicated that the strip had no false negative. This MRL-based multiple quantitative triazophos detection strip would provide a simple, direct, accurate and the most intuitionistic performance for the evaluation of agro product safety.
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Objective To measure the lethal dosage values ( LD50 ) of i.v.asarone injection for mice and to establish a standard for abnormal toxicity test of asarone injection to potentially reduce the occurrence of adverse drug reaction.Methods To obtain the LD50 value, a weighted linear probit regression method ( Bliss method) is employed. The limit of abnormal toxicity test is determined according to Appendix XI C in its 2010 edition of the Chinese pharmacopoeia.Results It is found that the LD50 of intravenously asarone injection in mice ranges from 51.9 to 153.1 mg/kg.The abnormal toxicity test should be added as an additional item in the standard.Conclusions Based on analyses in this study, an appropriate limit of abnormal toxicity test is 15 mg/kg, which is also in line with current medical standard in China.
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This research was conducted to investigate the correlations between urinary mercury concentration and each independent variable related with urinary mercury levels. the urinary mercury concentrations of 543 workers exposed to metal mercury vapor in a total of 11 fluorescent lamp manufacturing factories and at the same time mercury concentrations in air were measured from June 1989 to December 1989. And annually mercury consumption per workers, mercury consumption per lamp, numbers of breakage lamps, frequency of mercury infusion, numbers of droppers, and numbers of vacuum exhaustion pumps were also investigated. The results were as follows: 1. The geometric mean of airborne mercury concentration in a total of 11 factories was 47.9 microgram/m3 (5.8~352.2 microgram/m3), six factories(54.5%) of them were exceed the threshold limit value(50.0 microgram/m3). 2. The geometric mean of urinary mercury concentration among 543 workers was 84.3 microgram/l (1.13~533.9 microgram/l), the distribution of workers by urinary mercury concentration showed that 26 workers(4.8%) were above the mercury posioning level(300 microgram/l). 3. The correlation coefficient between urinary mercury concentration and monthly numbers of breakage lamps was the highest(0.74) and next was mercury consumption per lamp (0.67), annually mercury consumption per worker(0.63) in order.
Subject(s)
Korea , VacuumABSTRACT
This research was conducted to evaluate the effect of improvement in work environment and of segregation in a fluorescent lamp manufacturing factory. Among the total of 80 workers, 8 workers whose mercury concentration in urine reached a hazardous level (200-299 microgram/l) were moved to mercury free workplace. The follow-up examination for their mercury concentration in urine was done three times; on May 3, 1988, September 1, 1988 and April 3, 1989. The results were as follows: 1. Mercury concentration in the air was reduced from 0.140 to 0.107 mg/m3 in 4 months, and to 0.087 mg/m3 in one year after environmental improvement in workplace. However the level still exceeded the Threshold Limit Value. 2. The geometric mean of urinary mercury concentration among 80 workers was 173.0 microgram/l (5.1~458.6 microgram/l). The distribution of workers according to urinary mercury concentration showed that 9 workers (11.2%) were above the mercury poisoning level (300 microgram/l), 24 workers (30.0%) were 200-299 microgram/l, 35 workers (43.8%) were 50-199 microgram/l, and 12 workers (15.0%) were below 50 microgram/l. 3. Among the 24 workers whose urinary mercury concentration was 200-299 microgram/l, 8 were able to be followed up. Their mean urinary mercury concentration before segregation was 244.9 microgram/l, but decreased to 151.4 microgram/l in four months, 128.8 microgram/l in six months, and 46.8 microgram/l in one year after segregation.