Diagnostic and Interventional Radiology
Unspecified - Original Article

The antimicrobial efficacy of shielded ultraviolet germicidal irradiation in computed tomography rooms with intense human circulation


Department of Radiology, University of Health Sciences, Istanbul Fatih Sultan Mehmet Training and Research Hospital, İstanbul, Turkey


Department of Medical Microbiology, University of Health Sciences, Istanbul Fatih Sultan Mehmet Training and Research Hospital, İstanbul, Turkey

Diagn Interv Radiol 2020; 1: -
Read: 54 Published: 26 November 2020

PURPOSE: Computed tomography (CT) premises comprise one of the strategic points in the spread of hospital-acquired infections. Ultraviolet germicidal irradiation (UVGI) is potentially an important method to purify ambient air in them. However, it cannot be directly used in the presence of humans and it therefore is not operationally suitable in such units with continuous human circulation. Newer devices have been developed to purify air with more efficient and shielded UV-C sources. This study assessed the microbial air contamination in CT scanning rooms and investigates the efficacy and technical considerations of shielded UV-C arrays.

METHODS: Two shielded UVGI systems, each equipped with 15 Watt UV-C LED arrays, were tested in a very busy CT unit. One pilot study to determine ambient microrganisms in routine conditions and three basic scenarios for normal and abnormal conditions were investigated: (A) UVGI, air-conditioning (AC), and ventilation on; (B) UVGI and AC on and ventilation off; (C) UVGI on, AC and ventilation off. Ambient air were sampled in various time points before and after the initialization of UV irradiation and were analyzed for colony formation.

RESULTS: The mean total colony count in pilot study was 1360 ± 450 CFU/m3. Pre-UVGI colony count was 3510 CFU/m3 for Scenario A, 10000 CFU/m3 for Scenario B and 990 CFU/m3 for Scenario C. Thirty minutes after UVGI, total colony counts in all three scenarios dropped to 30 to 70 CFU/m3. Under normal operating conditions and UVGI the mean colony count was found as 21.4 ± 13.5 CFU/m3 and the average efficacy of the UVGI was found as 99.39%.

CONCLUSION: This study identified substantial microbial air contamination in CT scanning rooms during normal and abnormal operating conditions.  UV-C LED arrays effectively eliminates these microbiological contaminants. This effect is also observed in abnormal operating conditions where no other means of ventilation or air conditioning exists.

EISSN 1305-3612