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The Modified Barium Swallow Impairment Profile™© (MBSImP) is a standardized method for assessing physiology from fluoroscopic imaging during modified barium swallow (MBS) examinations. Although the protocol has been in use for 15 years, not all healthcare facilities utilize it for every MBS exam.
Radiology staff at the University of Alabama at Birmingham Medical Center evaluated the effect modifying dose mode and frame rate on radiation dose during MBS exams following 100% adoption of the MBSImP protocol in 2018. They reported in the September 2019 Clinical Radiology that radiation dose to patients was decreased without increasing fluoroscopy time.
The MBSImP standardizes training, administration, assessment, analysis, and reporting of results of MBS exams. Standardized barium volumes and consistencies shown to influence oropharyngeal function are used and results are reported in a structured template using a standardized vernacular. The MBSImP assesses 17 critical components of swallowing, and provides an objective profile of swallowing dysfunction.
Assistant professor of radiology in abdominal imaging and principal investigator Samuel J. Galgano, MD, said that the adoption of MBSImP had been gradual, done in conjunction with the medical center’s speech language pathology department. Before the profile was implemented, there was no standardization of the technique for inpatient MBS examinations. Fluoroscopy procedures were independently determined by clinical staff performing the exam for the pulse rate and dose setting.
Prior to MBSImP implementation, the authors wrote, the most commonly used MBS technique had been to use the fluoroscopic lowest pulse rate at 3.75 frames per second and a mean radiation dose of 5.86 mGy. To determine what modifications were needed, they tested two uniform phantoms of differing thickness to establish how changes in pulse rate and technique would affect patient radiation dose.
With initiation of the MBSImP, the pulse rate was uniformly increased to 15 frames per second and the default fluoroscope setting was changed to low dose, for a mean radiation dose of 4.72 mGy. The dose rate per second was 3.55 mGy compared to 4.35 mGy prior to standardization. The standardized protocol for the MBS and change in fluoroscopic technique reduced radiation dose exposure to patients by approximate 18.4%.
The authors pointed out that many different fluoroscopic times exist for MBS, and that opinions differ on the optimum frame rate needed to produce diagnostic fluoroscopic images. They selected a 15 frame per second mode because they were uneasy about immediately increasing the fluoroscopy rate from slow frame rate to continuous mode.
“Changing from slow rate to continuous was a rather drastic change for us, and we felt more comfortable adopting the protocol using an intermediate frame rate,” Principal investigator Samuel J. Galgano, MD, told Applied Radiology.  “However, we adopted continuous rate mode in 2018. We haven’t yet evaluated radiation dose changes, but we hope to do so. As radiologists, we strive to achieve the best diagnostic image quality while being conscientious of patient radiation dose during all of our exams.”
Galgano SJ, Gauntt D, Boyd MR, et al. Trade-off between pulse rate and radiation dose during modified barium swallow examination: what is the reality? Clin Radiol. 2019;74(9):736.e9-736.e12.