The Science behind Shadows and Measured UVC Dosing
The Tru-D® device's cornerstone for success is the power to measure the proper UVC dose needed for thorough room disinfection, resulting in the ability to disinfect in both direct (line-of-sight) and indirect (shadowed) areas. A disinfecting dose of UVC is a function of time and intensity. The Tru-D device’s technology will never compromise the proper time to deliver an adequate disinfecting dose to ensure microorganism reduction—this means that cycle times will vary from room to room, depending on the UVC dose necessary.
How does it work?
While other disinfection systems may deliver some UVC, they don’t compensate for room variables. The Tru-D device’s system measures, analyzes and delivers the proper dose of UVC energy to consistently and effectively disinfect every hard, non-porous surface in a room, even in high-touch, shadowed areas.
The Tru-D device’s Sensor360® technology minimizes the chance of human error by calculating the time needed to react to room variables – such as size, geometry, surface reflectivity and the amount and location of contents in the room. The Tru-D robot then effectively delivers the proper UVC dose during a single cycle from a single, central location in the room.
Other UVC offerings disinfect only line-of-sight surfaces very close to the machine and recommend moving the machine to multiple positions. Also, they have not been tested for UVC in shadowed areas and therefore cannot make the claim to do so. On the other hand, the Tru-D device measures the proper dose of UVC energy that reaches the walls and is reflected back to the center of the room. With the Tru-D device’s “dome” acting as the brain of the device, the UVC energy bounces off walls and glass to disinfect a room, including areas that are in the shadows.
The science that backs it up
Meaningful reduction in C. diff in indirect line of sight
The Tru-D device’s efficacy for disinfecting in shadowed areas has been well documented in numerous studies including “Room decontamination with UV radiation,” by Rutala, et al.1
“In our test room, the effectiveness of UV-C radiation in reducing the counts of vegetative bacteria on surfaces was more than 99.9% in approximately 15 minutes, and the reduction in C. difficile spores was 99.8% within 50 minutes,” the study reads. “UV-C radiation was more effective when there was a direct line of sight to the contaminant, but meaningful reduction did occur when the contaminant was not directly exposed to the UV-C (e.g., on the back of the computer or the back of the head of the bed).”1
Sensor360® compensates for room variables
The Tru-D device goes a step further than simply distance from the device and has been designed to also account for variability in hospital room size and setup. Not only does the Tru-D device compensate for shadowed areas, but also for the amount and location of furniture and equipment in the space, which has been validated by a number of independent, peer-reviewed studies1-3.
The authors further state, “The system that we evaluated is unique in that it uses measured UV-C intensities reflected from the walls, ceilings, floors, or other items in the room and calculates the operation time required to deliver the programmed lethal dose for microorganisms. The ability of the device to deliver lethal doses of UV-C to epidemiologically important microorganisms on nonreflective surfaces was evaluated, and we found that the quantities of these organisms were significantly reduced, reproducibly by 3–4 log10, under high contamination levels that exceed the levels normally found in healthcare facilities.”
Adequate dose is required for effective disinfection
In yet another study, “Ultraviolet-C decontamination of a hospital room: Amount of UV light needed” published in the Journal of the International Society for Burn Injuries4, noted the importance of providing an adequate dose of UVC energy to disinfect a room. The study was conducted in Sweden and used disposable indicators to determine how much UVC energy various surfaces in a burn unit received. The Tru-D device was used in the study.
“The amount of UVC radiation that is received in surfaces depends on their locations in the room (i.e. distance from the UVC emitter) and whether any objects shadow the light. In this study, we suggest that quality controls should be used to assure that enough UVC radiation reaches all surfaces,” the study states.
In conclusion, the authors stated, “The UVC dose received in a normally equipped burn ICU room after decontamination with a mobile UVC-emitting unit varies depending on the distance between the light source and the irradiated area and any objects in between that shadow. One must assure that an adequate dose has been received in shadowed and/or critical areas.”
SARS-CoV-2 inactivation in direct and shadowed areas
Lastly, in independent laboratory testing, the Tru-D device has been shown effective against SARS-CoV-2 in both direct and shadowed areas. An independent laboratory that performs environmental, food and life science testing for businesses, performed the efficacy testing. The testing demonstrated the Tru-D robot achieved 3 to 4 log10 reduction of the SARS-CoV-2 virus at up to 14 feet in both direct and shadowed areas.
Other UVC offerings position themselves as partial room disinfection and test their efficacy in direct line-of-site at differing cycle times due to their inability to measure UVC output. With the Tru-D Sensor360® technology, we have the ability to control and monitor the amount of UVC in a space, and it is backed by multiple, third-party, independent pieces of scientific literature as well as a well-documented and controlled lab test. When reviewing and purchasing UVC disinfection equipment, feel confident the environment is truly disinfected throughout the room by choosing a technology that measures its performance.
To learn more about the Tru-D device’s ability to disinfect in shadowed areas, click here.
- Rutala WA, Gergen MF, Weber DJ. Room decontamination with UV radiation. Infect Control Hosp Epidemiol. 2010;31(10):1025-1029.
- Nottingham M, Peterson G, Doern C, et al. Ultraviolet-C light as a means of disinfecting anesthesia workstations. Am J Infect Control. 2017;45(9):1011-1013.
- Rutala WA, Kanamori H, Gergen MF, Sickbert-Bennett EE, Weber DJ. Inactivation of Candida Auris and Candida albicans by ultraviolet-C [published online ahead of print, May 21]. Infect Control Hosp Epidemiol. 2021;1-3
- Linblad, M, et al. Ultraviolet-C decontamination of a hospital room: Amount of UV light needed. Journal of the International Society for Burn Injuries. 202046(4): 842-849.
- October 2020, Evaluation of Virucidal Efficacy by Tru-D’s UV Device on a Surface – Severe Acute Respiratory Syndrome-Related Coronavirus 2 (SARS-CoV-2)