Estimation of effective dose and radiation risk in pediatric barium studies procedures
Introduction
Radiological exposure to radiation for medical purposes is the largest human-made source of radiation exposure worldwide ((0.6 mSv per capita annually) (UNSCEAR, 2010). Medical exposure of children to ionizing radiation has a massive benefit by diagnosing many clinical condition. However, X rays is a known carcinogenic agent to which infants and children are predominantly vulnerable compared with adults receiving the identical radiation dose (ICRP, 2013). Their sensitivity to radiation is highest during childhood two to three times that of adults due to their greater cell division rate and longer expected lifetime, which allows tumor induction process to manifest. Recent studies showed that also exposure to ionizing radiation may increase the risk of non-cancerous effects such as cardiovascular disease (ICRP, 2013). Therefore, there is massive need to protect children from avoidable or unnecessary radiation during medical procedures. Barium sulfate (BaSO4), is used as a contrast medium for study the anatomy and physiology of the gastrointestinal tract since its emergence in 1910 due to its high atomic number (ZBa = 56) compared to soft tissues (Z = 7.4) and excellent coating properties of GIT mucosa (Carver and Carver, 2012). Gastrografin, which is water-soluble iodinated radiopaque contrast medium for oral or rectal administration is used as alternative if barium sulfate contraindicated (Z = 53) since its introduction in 1954 (Ginai, 1987). Depending on the organs to be examined, barium radiographs can be classified into upper gastrointestinal examinations (barium swallow, barium meal, barium follow-through) and lower gastrointestinal examinations (enteroclysis (small bowel enema) and barium enema)). In addition to its diagnostic role, barium studies have documented therapeutic role in certain conditions (Matsuura et al., 2015). Although the use of traditional contrast studies under fluoroscopy has been declining due to modern sectional imaging and other alternative diagnostic modalities (endoscopy), barium studies (except barium meal) are still more sensitive in many clinical condition (Hersh et al., 2016; Hart et al., 2009; Ciraj-Bjelac et al., 2015, ACR, 2016). During barium procedures, fluoroscopic and radiographic image acquisition frequently used, at different exposure parameters, patient weight and X ray machine characteristics. Infants and children constitute approximately 10% (250 million procedures/year) of the total number of radiological examinations (UNSCEAR, 2013). It has been estimated that the frequency and collective dose from GIT procedures are 4.8% and 14.5%, respectively. It was estimated that 6% of gastrointestinal procedures performed on children (UNSCEAR, 2013). Although, the patient doses from barium studies procedure is low and the benefit outweigh the risk when the procedure is justified and optimized appropriately, can lead non negligible radiation induced cancer risk (Brenner et al., 2001, Sulieman et al., 2016). Moreover, it has been estimated that 20–50% of radiological procedures may be unjustified (Malone et al., 2012; Lee et al., 2004; Brenner et al., 2001). Therefore, application of radiation protection measures is useful in protection against unnecessary radiation exposure. Precise justification of the procedure by qualified medical practitioner, optimization of the exposure parameters and establishment of dose reference levels are valuable tools to minimize radiation exposure to its lowest value. The radiation doses from barium studies procedure in literature ranges between 1.4 mSv to 24.0 mSv per procedure (Chapple et al., 1992, Ciraj-Bjelac et al., 2015, ICRP, 2013, Livingstone et al., 2008, Staton et al., 2007, Sulieman et al., 2011, Sulieman et al., 2014). The number of published data is limited compared to the frequency of the procedure and the radiation risk to this sensitive group. In addition to that, a wide range of radiation doses were reported suggesting that still pediatric patients may espoused to avoidable radiation exposures. Furthermore, many children may undergo the procedure repeatedly, resulting in highest radiation doses (Hersh et al., 2016). Therefore, measurement of radiation dose to pediatric patients is crucial. Finally, different radiation units and dose quantities are used to quantify the radio diagnostic procedures such as kerma area product (KAP, mGy cm2), and entrance surface air Kerma (ESAK, mGy). Thus, estimation of effective dose and radiation risk will allow comparison of the dose value between different procedures. The objective of this study were to evaluate the ESAK related to pediatric barium studies and to estimate the organ and effective doses and its radiation risks (Fig. 1).
Section snippets
Patient data
A total of 69 pediatric patients with different clinical indication were referred to two radiology departments for barium swallow, meal and enema. All the patients were performed by senior technologist using departments’ protocols. The ethics and research committee approved this study Research Council (College of Medical Radiologic Sciences, Sudan University of Sciences and Technology, Khartoum, Sudan). Patients demographic data (e.g. age (year)), weight (kg), body mass index (BMI (kg/cm2)),
Results
Patients included 69 consecutive procedures with mean age range 4.2(0.4–12.4) years. There were 38 girls and 31 boys. Table 1 present the clinical indication of this study. Table 1, showed that 34.8% (24 patients) of the sample was barium meal, 26% (18 patients) were undergone barium swallow while 39.1% (27 patients) of the sample were barium enemas. Table 2 presented the patient demographic data in terms of age (years), weight (kg), height (cm) and BMI (kg/cm2). Patient demographic data were
Discussion
Barium studies are of special interest because it contribute almost one fifth of the collective doses (UNSCEAR, 2000). This study aimed to assess pediatric radiation doses and radiation risks during certain barium studies procedure. Wide range of clinical indications for barium studies for pediatric patients (Table 1). This increase the difficulty of designing a standard protocol for radiation dose optimization. Therefore, the procedure remain operator dependent. In this context, Bibbo et al.
Conclusions
For the GIT, this study indicates the need of radiation exposure reduction to patients, and underlines the importance of the protection in pediatric imaging for GIT. The unnecessary radiation exposure can be reduced significantly by reducing the number of films and screening time. Although, the radiation dose to the patients was low, but this values contain large uncertainty since this study was conducted in children and the other studies were performed in adults' patients. In addition to that,
Acknowledgements
The authors extend their appreciation to the Deanship of Scientific Research at King Saud University for funding this work through research group No (RG-1438-072)
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