Radiation exposure contribution of the scout abdomen radiograph in common pediatric fluoroscopic procedures

Radiation dose monitoring in pediatric fluoroscopy: comparison of fluoroscopy time and dose-area product thresholds for identifying high-exposure cases

BACKGROUND

Fluoroscopy time has been used as a surrogate for radiation dose monitoring in pediatric fluoroscopy; however it does not account for factors such as magnification or collimation. Dose-area product (DAP) is a more accurate measure of radiation exposure but its dependence on patient weight and body-part thickness is a challenge in children of varying ages.

OBJECTIVE

To determine whether fluoroscopy time and DAP produce concurrent results when they are used to identify high-exposure cases, and to establish radiation dose thresholds for our institution.

MATERIALS AND METHODS

During a 2-year period we prospectively monitored pediatric fluoroscopy studies performed at the Children's Hospital at Montefiore. We recorded study type, fluoroscopy time, DAP, patient age, weight and height. We then calculated 90th percentile fluoroscopy time and DAP thresholds for weight and age.

RESULTS

We evaluated 1,011 cases (453 upper gastrointestinal [UGI] series, 266 voiding cystourethrograms [VCUGs], 120 contrast enemas, 108 speech studies, and 64 esophagrams). Fluoroscopy time demonstrated moderate correlation with DAP (r_s=0.45, P<0.001, Spearman rank). DAP strongly correlated with patient weight (r_s=0.71, P<0.001) and age (r_s=0.70, P<0.001). Concordance of cases exceeding 90th percentile thresholds for fluoroscopy time and DAP were κ=0.27 for UGI series and κ=0.49 for VCUG for weight-based cutoffs, and κ=0.36 for UGI series and κ=0.40 for VCUG for age-based cutoffs.

CONCLUSION

The limited correlation of fluoroscopy time with DAP suggests these methods are not equivalent for dose monitoring. However, the strong correlation of DAP with patient weight and age presents a challenge for establishing DAP thresholds in children, who range widely in size. Despite controlling for weight or age, there was limited overlap of cases exceeding the 90th percentile threshold for fluoroscopy time and DAP. This further reinforces the non-overlapping outcome of these two methods and indicates that fluoroscopy time might be inadequate for dose monitoring.

Is the Scout Out? The Utility of Scout Radiographs in the Pediatric Upper Gastrointestinal Examination

OBJECTIVE

The aim of the study is to demonstrate the scout radiograph does not change patient management, alter planning, or contribute to interpretation of the outpatient pediatric upper gastrointestinal fluoroscopic examination (UGI).

METHODS

We retrospectively reviewed 197 outpatient pediatric UGIs performed over a 2-year period. We performed a chart review on all patients to evaluate for potentially clinically significant findings on the scout radiograph. Scout findings were categorized into 4 groups: no new clinically significant findings (group 1), potentially clinically significant findings that were not directly addressed in the electronic medical record (group 2), incidental non-gastrointestinal (GI) findings that necessitated further workup, however, were later deemed insignificant (group 3), and clinically significant findings that changed patient GI management, altered the planning of the procedure, or contributed to the interpretation of the fluoroscopic study (group 4).

RESULTS

A total of 197 UGIs were analyzed. A significant majority of cases (97.0%) were classified into group 1. Three cases (1.5%) were classified into group 2 with findings not addressed in the medical record. Two cases (1.0%) were classified into group 3, which, after further workup, were deemed not clinically significant. One case (0.5%) was classified into group 4, which resulted in a change in patient GI management.

CONCLUSIONS

In our review, there was only 1 case in which the scout radiograph changed patient GI management, with moderate stool burden leading to a miralax cleanout, although there were no cases, which altered the planning of the procedure or contributed to the interpretation of the study. The scout radiograph can be omitted and/or substituted with the last image hold function to decrease radiation exposure.

Intussusception reduction: Effect of air vs. liquid enema on radiation dose

BACKGROUND

Both air and radiopaque liquid contrast are used to reduce ileocolic intussusception under fluoroscopy. Some suggest air lowers radiation dose due to shorter procedure times. However, air enema likely lowers radiation dose regardless of fluoroscopy time due to less density over the automatic exposure control cells.

OBJECTIVES

We test the hypothesis that air enema reduction of ileocolic intussusception results in lower radiation dose than liquid contrast enema independent of fluoroscopy time. We describe a role for automatic exposure control in this dose difference.

MATERIALS AND METHODS

We retrospectively evaluated air and liquid intussusception reductions performed on a single digital fluoroscopic unit during a 26-month period. We compared patient age, weight, gender, exam time of day and year, performing radiologist(s), radiographic image acquisitions, grid and magnification use, fluoroscopy time and dose area product. We compared categorical and continuous variables statistically using chi-square and Mann-Whitney U tests, respectively.

RESULTS

The mean dose area product was 2.7-fold lower for air enema, 1.3 ± 0.9 dGy·cm², than for liquid, 3.5 ± 2.5 dGy·cm² (P<0.005). The mean fluoroscopy time was similar between techniques. The mean dose area product/min was 2.3-fold lower for air, 0.6 ± 0.2 dGy·cm²/min, than for liquid, 1.4 ± 0.5 dGy·cm²/min (P<0.001). No group differences were identified in other measured dose parameters.

CONCLUSION

Fluoroscopic intussusception reduction using air enema uses less than half the radiation dose of liquid contrast enema. Dose savings are independent of fluoroscopy time and are likely due to automatic exposure control interaction.

Pre-procedural scout radiographs are unnecessary for routine pediatric fluoroscopic examinations

BACKGROUND

Although practice patterns vary, scout radiographs are often routinely performed with pediatric fluoroscopic studies. However few studies have evaluated their utility in routine pediatric fluoroscopy.

OBJECTIVE

To evaluate the value of scout abdomen radiographs in routine barium or water-soluble enema, upper gastrointestinal (GI) series, and voiding cystourethrogram pediatric fluoroscopic procedures.

MATERIALS AND METHODS

We retrospectively evaluated 723 barium or water-soluble enema, upper GI series, and voiding cystourethrogram fluoroscopic procedures performed at our institution. We assessed patient history and demographics, clinical indication for the examination, prior imaging findings and impressions, scout radiograph findings, additional findings provided by the scout radiograph that were previously unknown, and whether the scout radiograph contributed any findings that significantly changed management.

RESULTS

We retrospectively evaluated 723 fluoroscopic studies (368 males and 355 females) in pediatric patients. Of these, 700 (96.8%) had a preliminary scout radiograph. Twenty-three (3.2%) had a same-day radiograph substituted as a scout radiograph. Preliminary scout abdomen radiographs/same-day radiographs showed no new significant findings in 719 (99.4%) studies. New but clinically insignificant findings were seen in 4 (0.6%) studies and included umbilical hernia, inguinal hernia and hip dysplasia. No findings were found on the scout radiographs that would either alter the examination performed or change management with regard to the exam.

CONCLUSION

Pre-procedural scout abdomen radiographs are unnecessary in routine barium and water-soluble enema, upper GI series, and voiding cystourethrogram pediatric fluoroscopic procedures and can be substituted with a spot fluoroscopic last-image hold.