Hospitals currently rely on simple human visual inspection for assessing cleanliness of surgical instruments. Studies showed that surgical site infections are in part attributed to inadequate cleaning of medical devices. Standards groups recognize the need to objectively quantify the amount of residues on surgical instruments and establish guidelines. We developed a portable technology for the detection of contaminants on surgical instruments through fluorescence following cleaning. Weak fluorescence signals are usually detected in the obscurity only with the lighting of the excitation source. The key element of this system is that it works in ambient lighting conditions, a requirement to not disturb the normal workflow of hospital reprocessing facilities. A biocompatible fluorescent dye is added to the detergent and labels the proteins of organic residues. It is resistant to the harsh environment in a washer-disinfector. Two inspection devices have been developed with a 488nm laser as the excitation source: a handheld scanner and a tabletop station using spectral-domain and time-domain ambient light cancellation schemes. The systems are eye safe and equipped with image processing and interfacing software to provide visual or audible warnings to the operator based on a set of adjustable signal thresholds. Micron-scale residues are detected by the system which can also evaluate soil size and mass. Unlike swabbing, it can inspect whole tools in real-time. The technology has been validated in an independent hospital decontamination research laboratory. It also has potential applications in the forensics, agro-food, and space fields. Technical aspects and results will be presented and discussed.
Fluorescence intensity is often standardized by comparing the unknown sample signal to that of a reference solution with
a known concentration of a reference fluorophore. To use this technique for in vivo fluorescence reflectance
measurements standardization, a reference sample that also mimics the scattering and absorption properties of the tissue
would need to be used. A simpler approach to fluorescence reflectance measurements standardization is to express the
intensity of the measured fluorescence as a ratio of the excitation irradiance to the fluorescence radiance. This ratio of
radiometric quantities can be measured by normalizing the measured fluorescence image to a reflectance image acquired
with a reflection standard at the excitation wavelength (without the emission filter). Instruments could be calibrated to
report their intensity results using this dimensionless ratio. The calibration could also be transferred from a reference
calibrated instrument to other instruments through the use of fluorescence phantoms. Reporting fluorescence intensity
measurements using this dimensionless ratio will ease instrument standardization and comparison of fluorescence
reflectance results between instruments, vendors and applications.