Doses from pediatric CT examinations and level of optimization of the scan protocols in the Nordic countries

摘要

Introduction: Doses to pediatric patients from CT examinations are known to be unnecessarily high if scan protocols developed for adult patients are adopted. Use of optimized size-specific pediatric scan protocols is essential to keep the doses at an appropriate level. The aim of this study was to estimate doses to pediatric patients from CT examinations and to evaluate the level of optimization of the scan protocols used in the Nordic countries. Material and method: Applied scan parameters, clinical indication and patient data were collected for four examination areas (brain, chest, abdomen and whole body) from totally 20 hospitals within the Nordic countries. The available dose data on the scanner console, CT Dose Index corrected for pitch (CTDI_(vol)) and Dose Length Product (DLP) was also collected. Effective doses were estimated by multiplying DLP with conversion factors (published by Chapple et al, 2001) available for four separate scan areas (head/neck, chest, abdomen and pelvis). To best represent a pediatric body, the DLP for a standard head phantom (diameter 16 cm) was assessed and used for the effective dose estimates. Preliminary results and discussion: Totally 359, 272, 192 and 73 scan protocols were received for pediatric CT examinations of respectively the brain, chest, abdomen and whole body. Preliminary calculations of the range (min-max) of the reported consol CTDI_(vol) were 7.4-140.0, 1.6-15.1, 1.7-25.5 and 1.7-55.0 mGy for examinations of respectively the brain, chest, abdomen and whole body, while the corresponding range in consol DLP were 7-1783, 6-801, 29-1054 and 54-2144 mGy(centre dot)cm. The age of the patients examined varied from 0 to 16 years and the most common clinical indications were trauma and tumor or controls of these indications. The mean effective dose for examinations of the brain, chest, abdomen and whole body was 2.9, 2.1, 4.4 and 5.5 mSv, respectively. Finalizing the dose calculations from all countries, the results will give valuable information of the dose levels to pediatric patients in the Nordic countries, especially when they are analyzed with respect to age, sex and clinical indication. When combined with the underlying scan parameters, the degree of optimization of the scan protocols applied to pediatric patients will be evaluated. Establishment of some common Nordic diagnostic reference levels for pediatric CT examinations will be considered when the dose results are finalized.