INTRODUCTION: Endoscopic retrograde cholangiopancreatography(ERCP)is an important therapeutic tool in billary and pancreatic disorders and relies heavily on the use of fluoroscopy.Dose area-product(DAP) is considered to be the most appropriate dosimetric quantity and it is used in Monte Carlo simulation to calculate the effective radiation dose to patients.
AIMS & METHODS: The aims of the study were to determine patient irradiation during ERCPs and to see if there is any correlation between DAP and fluoroscopy duration or if these two parameters were influenced by the endoscopist experience or by exam difficulty.Diagnostic reference levels (DRLs)were also assessed for ERCPs.Data were prospectively collected from consecutive ERCPs performed during a 3 months period.For each exam, the following data were collected: patient's characteristics(age,sex,weight),fluoroscopy duration, DAP, procedure difficulty(easy,normal or difficult) and the operator experience.The ERCPs were carried out by two seniors(>2000 ERCPs) and one junior(<250 ERCPs) operators. The statistical analysis was performed with the non-parametric Mann-Whitney test and the analysis of variance with ANOVA test.
RESULTS: 92 patients(49M,43F),mean age 65 years(range 29-94years) were included.Overall,the mean fluoroscopy duration was 8.6min(range:0.8-48min,75th percentile:11.6min) and the mean DAP value was 20.6Gy.cm2(range:2.2-147Gy.cm2,75th percentile:26Gy.cm2).A good correlation was observed between the fluoroscopy duration and the DAP value, as described by the formula:DAP(Gy.cm2)=2.5 Gy.cm2xmin-1xT(min)(r2=0.8216)and between the difficulty of the procedure and the two fluoroscopic parameters.The DAP value and the fluoroscopy duration were poorly correlated with patient's weight(r2=0.069).There was no correlation between DAP or fluoroscopy duration and both the procedure difficulty and the operator experience(p=0.91,respectively 0.58,ANOVA test).Endoscopist experience did not significantly influence the distribution of DAP(p=0.15) and fluoroscopy duration(p=0.44). TABLE 1: Table 1: Mean fluoroscopy duration and mean DAP value for easy, normal and difficult E Exam DifficultyNumber of ExamsMean Fluoroscopy duration (min) XMean DAP (Gy.cm2)y Easy152.8±2.3 7.5±1.0Normal446.6±0.6 14.9±1.8 Difficult3314.3±1.7 34.9±5.2 x p=0.0001 easy vs. normal,p< 0.0001 normal vs. difficult, p<0.0001 easy vs. difficult.
CONCLUSION: A good correlation was observed between the fluoroscopy duration and DAP value.The assessed DAP value can be used as a base to define DRLs for ERCP procedures.For the first time we show that DAP values and fluoroscopy duration were significantly dependent on the difficulty of the procedure and that the operator experience had no influence on these parameters.