Patient dose during videofluoroscopy swallowing studies in a Hong Kong public hospital

A videofluoroscopy swallowing study (VFSS) is a major tool in diagnosing swallowing disorders. Like all other medical examinations that involve irradiation, patient dosage is a major concern. Cerebrovascular accident (CVA) and nasopharyngeal carcinoma (NPC) have been two of the most common indicating pathologies for VFSS studies. The goals of this study were to determine the mean dose area product (DAP) value and fluoroscopic time for VFSS examinations in Tuen Mun Hospital, to compare the result with the dose reference level of other similar studies, and to document the results with respect to the various common indicating pathologies for VFSS (i.e., CVA, NPC). Three hundred ninety-eight VFSS exams were performed at our center in a 24-month period; the mean DAP was 2.42 +/- 2.04 Gy cm(2) for an effective dose of 0.31 +/- 0.26 mSv. The mean fluoroscopic time is 4.23 +/- 2.56 min. The P value of 0.0034 was obtained using the Kruskal-Wallis test to compare the DAP from various groups of indicating pathologies. It suggests that there are significant differences in dosage between CVA and NPC patients and the entire population. We conclude that the dose of radiation received by a patient undergoing a VFSS examination in our center was comparable to the international standard and that of other similar studies. We can also conclude that there is a significant difference in dosage between NPC and CVA patients and the overall population suggesting that the indicating pathologies for a VFSS have certain effects on the resulting irradiating dose delivered but more studies have to be done to explain such differences.