The Radiation Dose Level Research Of CT Examination In Children In Jiangsu Province

Objective:To get knowledge of the difference of scanning parameters and radiation dosereceived between different hospitals on children CT scanning in Jiangsu province. Toset up the diagnostic reference levels of CT examination in children in Jiangsu province,and to reduce the radiation dose through optimizing the scanning parameters.Methods:1. To complete the review, through data investigation and literature; To make formand determine the research plan, through field investigation, with the help ofprofessional teacher; To collect and analyze data, through professional training, with thehelp of experts and computed tomography operator.2. According to the difference of geographical location, economic and medicallevel, we selected the seven different spiral CT from7hospitals in Jiangsu province;Taking the way of random, we collected and recorded10sets of data for each age group(<1year old,1~5years old,6~10years old,11~15years old) in head, chest,abdominal computed tomography examination from each CT, including the patients’general information, main scanning parameters and showed dose, etc.3. Using Barracuda detector, TM160CT dose of X-ray/CT quality control mode (Φ16cm), as well as100mm pen type chamber instrument, when choosing actually checkscanning sequence, and in the same scanning parameters, such as kVp, mAs, pitch, wemeasured and recorded the CT dose index (CTDI100), and then calculated CTDIw, DLPand effective dose in accordance with the relevant formula.4. To compare the differences of scanning condition selection and radiation dose ofhead, chest and abdomen Multi-Detector CT examination of paediatric patients (＜1year old,1~5years old,6~10years old,11~15years old)at seven hospitals in Jiangsuprovince, and then to optimize the scanning conditions. 5. We recommend a survey of75quantile as the diagnostic reference level of CTexamination in children in Jiangsu province. Comparing with foreign similar research inthis study in children CT radiation dose levels and their differences in the selection ofscanning parameters, we put forward reasonable suggestions.6. Data were represented in, and SPSS17.0statistical program was used toanalyze data. Kolmogorov-Smirnov test was used to examine whether the two sampleswere from the same distribution, and student ’s t test was used to analyze the differencesbetween the two sample mean; One-way analysis of variance (ANOVA) was used to testthe mean differences between multiple samples, with Least-Significance-DifferenceMethod (LSD) for multiple multiple comparisons between the sample mean. Andmultiple linear regression analysis was used to evaluate the correlation of kVp, mAs, thelength of scanning and DLP values. P <0.05for the difference was statisticallysignificant.Results:1. Radiation dose caused by CT examination in children in7hospitals havesignificant difference (P <0.01), mainly due to the choice of mAs between differenthospitals have the significant difference (P <0.01), and the scan length option in chest,abdominal examination exists significant difference (P <0.01), and the selection ofpitch factor in chest, abdominal examination were different (0.7~1.0).2. The kVp, mAs and CTDIwwere positively correlated, and the partial regressioncoefficient were0.22,0.84, fitting regression equation for y=0.33x1＋0.19x2－40.8;The kVp, mAs and scanning length was positively related with DLP, and the partialregression coefficient were0.20,0.76,0.61, fitting regression equation for y=4.7x1＋2.8x2＋18.5x3－865.3. The mean (range) value of CTDIwon paediatric patients during head, chest andabdomen CT scanning in this research were34.9±15.2mGy (15.3~86.9mGy),14.8±7.1mGy (2.5~35.6mGy),21.3±7.5mGy (7.1~42.4mGy); The mean (range)value of DLP on paediatric patients during head, chest and abdomen CT scanning were422±232mGy·cm (107~1373mGy·cm),266±146mGy·cm (35~965mGy·cm),464±224mGy·cm (71~1179mGy·cm); The mean (range) value of effective dose onpaediatric patients during head, chest and abdomen CT scanning were2.46±1.57mSv(0.61~10.40mSv),5.69±2.48mSv (1.36~17.38mSv),11.86±5.28mSv (2.55~34.27mSv). 4. The diagnostic reference levels of CT examination in children in Jiangsuprovince established by this study are relatively close to the British Shrimptondiagnostic reference levels in2003. But comparing with Verdun’s research inSwitzerland in2008and the German Galanski’s results in2006, radiation dose in lowage group, the chest and abdomen CT examination of this study are on the high side,and the difference was statistically significant (P <0.05).5. Comparing with the2008German Galanski’s research, there were no significantdifferences between the selection of kVp, layer thickness, pitch and scan length in headCT examination in this study; But in the chest and abdomen CT examination, smallpitch factor was selected in this study, and choice of mAs is definitely too high, whichcaused CTDIw, DLP significantly increased. Absolutely, all have significant difference(P <0.01).Coculusions:1. The kVp, mAs and CTDIwwere positively correlated, and the kVp, mAs andscanning length was positively related with DLP.2. The diagnostic reference levels of CT examination in children in Jiangsuprovince established by this study are relatively close to the British diagnostic referencelevel in10years ago. But the radiation dose in low age group, the chest and abdomenCT examination of this study are apparently higher than Switzerland’s and German’s.3. There are unreasonable phenomenon in the choice of scanning conditions in CTexamination of paediatric patients in Jiangsu province, mainly displays in: choosing theappropriate parameters not in strict accordance with age, weigh of the children; highchoice of mAs in the chest and abdomen CT examination, small pitch factor selection,which caused to high dose levels.4. Through the establishment of the diagnostic reference levels of CT examinationin children in Jiangsu province, we can optimize the scanning parameters, standardizethe procedures of diagnosis and treatment, and reduce the radiation dose in children CTexamination.