Clinical Audit of Radiation Dose Reduction in Micturating Cystourethrogram: an Initiative for Patient Safety and Quality Improvement
KYA Au, WCW Wong, LSJ Khoo
Hong Kong J Radiol 2016;19:170-82
DOI: 10.12809/hkjr1615384
Objectives: To ensure that the radiation dose from micturating cystourethrograms (MCUs) performed in our centre is regularly and constantly reviewed, and to identify ways in which radiation dose can be reduced and maintained in line with international standards.
Methods: This was a clinical audit of the radiation dose and fluoroscopic screening time of MCU examination performed in 97 patients between April 2013 and June 2015 at a tertiary referral centre in Hong Kong before and after implementation of radiation reduction measures. Along with the general measures to reduce radiation dose, the three major measures taken were (1) minimising fluoroscopic screening time during the early-to-intermediate bladder filling phases during which time only limited diagnostic information was obtained; (2) bilateral fluoroscopic screening of the urinary tract in one voiding cycle to detect reflux, thus avoiding the need for two voiding cycles; and (3) using a mathematical formula to estimate the time when urinary bladder capacity was reached and the child might start to void. Statistical analysis was performed of dose area product (DAP) and fluoroscopic screening time during the MCU and compared with the diagnostic reference level (DRL) set by the UK’s National Radiological Protection Board.
Results: The mean DAP of MCUs in our hospital before and after implementation of dose reduction measures was 49.3 uGym2 and 38.1 uGym2, respectively, with a statistically significant reduction in DAP of 22.7% (p = 0.036). A similar reduction of 20.6% was also observed in the fluoroscopic screening time that reduced from a mean of 115.3 seconds before to 91.6 seconds after dose reduction measures (p = 0.002). Overall, a reduction in radiation dose from our MCU examinations from 20.2% above the DRL to below the third quartile was observed.
Conclusion: A statistically significant 22.7% reduction in radiation dose from MCU examinations was achieved after the implementation of dose reduction measures in our hospital. This has also resulted in a mean radiation dose that is below the third quartile of the DRL of the UK's dose reference level.
中文摘要
有關排尿式尿道膀胱造影輻射劑量減少的臨床審計：病人安全和質量改進的倡議
區嘉殷、黃慧中、邱麗珊
目的：確保本院定期並不斷地評價排尿式尿道膀胱造影（MCU）時產生的輻射劑量，並找出能減少輻射劑量以及與國際標準保持一致的措施。
方法：本臨床審核研究於香港一所三級轉介中心內進行。在減少輻射劑量措施實施前後，比較輻射劑量和暴露在X光射源下的時間。研究對象為2013年4月至2015年6月期間的97名病人。除一般的減少輻射劑量措施外，還實施了以下三項主要措施：（1）由於早期至中期的膀胱充盈期間所獲得的診斷資料有限，應盡量減低病人暴露在X光射源下的時間。（2）在一個排尿周期內檢測膀胱兩側的回流，替代以往的兩個排尿周期，這樣可減低病人暴露在X光射源下的時間。（3）使用數學公式來估計膀胱脹滿尿液的時間而可以讓兒童可以開始排尿。利用統計學分析MCU期間的劑量面積乘積（DAP）和暴露在X光射源下的時間，並與英國國家輻射保護委員會設定的診斷參考水平（DRL）進行比較。
結果：本院在減少輻射劑量措施實施前後的DAP分別為49.3 uGym2和38.1 uGym2；下降幅度為22.7%，並統計顯著（p=0.036）。暴露在X光射源下的時間則由方法實施前的115.3秒減至實施後的91.6秒；下降幅度為20.6%（p=0.002）。總的來說，MCU檢測中輻射劑量的減少從實施前在英國DRL之上的20.2%減至實施後DRL第三四分位數以下。
結論：本院在減少輻射劑量措施實施後，MCU輻射劑量顯著下降了22.7%。平均輻射劑量亦減至按英國DRL標準的第三個四分位數以下。