Purpose: At our institution, children suspected of having inhaled a foreign body undergo a four-view radiographic study. Objects like soft food may not be readily identified on radiographs and the patient will need bronchoscopy under general anesthesia. The goal of this work was to develop and evaluate an ultra-low dose CT (ULDCT) protocol optimized for airway visualization to replace radiographic examinations and preclude unnecessary bronchoscopy.
Methods: Effective doses for a four-view radiographic exam were estimated based upon AP and lateral chest radiographs of 20 pediatric patients using NCIRF. Additionally, effective dose for 37 pediatric patients that received a standard-dose chest CT were retrieved from Radimetrics. Techniques of the ULDCT protocol were set to 80 kVp, fixed 10 mAs, the lowest technique factors available on the CT scanner, and 5 mm slice thickness with a 1 mm slice interval. This protocol was tested using a five-year-old Atoms Family reference phantom and a custom-made gelatin phantom. Inhaled foreign bodies were simulated by inserting soft food into plastic tubing and placing the tubes into these phantoms. Phantoms were imaged under the radiographic and ULDCT protocol. Resulting images were compared qualitatively for diagnostic information
Results: The average effective dose for a four-view radiography exam and a standard-dose chest CT were found to be 0.12 mSv and 2.7 mSv, respectively. Effective dose for the ULDCT was 0.13 mSv. Replacing the radiographic exam with ULDCT results in a 0.01 mSv (8.3%) dose increase, and a 2.71 mSv (95%) dose reduction in patients who would have received an additional standard-dose CT. Visibility of foods in ULDCT was superior to that in the radiographic exams and comparable to that in a standard-dose CT.
Conclusion: The ULDCT protocol achieved an effective dose similar to a four-view radiograph exam while providing additional diagnostic information and faster diagnosis compared to radiography.
Not Applicable / None Entered.