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Abstract

Magnetic resonance imaging (MRI) is a diagnostic method that is used for broad range of
hospitalized patient, emergency patients, chemotherapy treated and as well the patients
that may have infectious diseases. Because the examinations of different patients are
usually performed with the same equipment in the same environment, the surfaces of the
equipment and examination rooms could represent a reservoir for pathogenic
microorganisms and source of transmission of infections to patients and healthcare
professionals. Therefore, it is of at most importance to assure efficient hygienic and
disinfection procedures. However, modern electronic diagnostic equipment is difficult to
disinfect quickly and successfully. The market does not offer an adequate, reliable, rapid
and safe disinfection process for the complex diagnostic devices such as MRI. In MRI
diagnostic rooms, the method of disinfection is problematic due to the gravity force of 3.0
Tesla, which is present all the time. Most material of disinfection equipment is incompatible
with the ferromagnetic field. For disinfection in healthcare many manufacturers recommend
methods such as UV lights and UV robots, and the use of certain aggressive chemicals that
however should not be used in contact with specially adapted coils and their sensitive
surfaces.The main factor of successful disinfection is time itself. Selection of a suitable
disinfectant is largely dependent on the overall process of disinfection procedure.
Consequently, new approaches to disinfection procedures have been studied. Thanks to
its mechanism of action, electrolyzed oxidizing water (EOW) has been considered as a
promising biocide of the new generation. The principle of the EOW production has been
known for some time now. Basically, the alkaline ionized water and acid oxidized ionized
water are generated from diluted non-iodized cooking salt (NaCl solution), whereby the
alkaline fraction reaches a pH of 11–12, while the acid one has a pH of 1–3. While the
alkaline ionized water is considered to have a cleaning effect, the acid one has extremely
biocidal effect. Mostly, the effect of the EOW action has been attributed to the pH change
only. More detailed analysis has revealed that EOW works through several mechanisms.
Among them, the most important ones for the biocidal effect are the redox potential,
generated oxidized and super-oxidized ions, and to a smaller extent the produced chlorides,
sodium hypochlorite and residual chlorine. Moreover, EOW is characterized by a marked
deficiency of electrons due to which it has a tendency for electro-neutral environment that
can be achieved only through the abstraction of electrons from the surrounding
environment. If there are any micro-organisms in that environment, EOW abstracts the
electrons from their membrane disrupting their balance and thereby causing their death.
For the aplication in the air and on surfaces we use a cold fogging method. For the cold
fog method we need a aerosolizator for special conditions with special nozzel, compressed
air and EOW(Pintarič, 2015). In 2013, for the purpose of cold fogging on the 3T MRI, a
modified OPTI-JET CS MD 1 MR was developed with the micronozzle witch gawe us a
range of 20-30 microns of droplet size. We demonstrated the efficiency and reliability of
the hard-to-reach places of magnetic resonance. The amount of the Steriplant© N biocide
was used in the air at 6-8 ml/m3 was accurately analyzed. For a more precise analysis of
the amount of biocide used in the air and on surfaces, we want to determine the maximum
load limit with the biocide Steriplant© N and improve the method of aerosolization. With
this method we use the properties of aerosols. Aerosols are two-phase systems, consisting
of the particles and the gas in which they are suspended. The aerosols applicated in such
way to air have some benefits but also some problems for the medical staff. Because the
toxicity of inhaled particles depends on their physical as well as their chemical properties,
an understanding of the properties of aerosols is required to evaluate airborne particulate
hazards. The research was carried out on a chamber simulation model that was produce
and use for the purpose of the test item (Steriplant© N) aerosols on the viability
(cytotoxicity) and induction of DNA double-strand breaks in human alveolar epithelial
cells A549 in vitro. The research on this chamber simulation model was carried out at the
National Institute of Biology (NIB) in Ljubljana. For this research, testing and analysis of
air flow and aerosolization we build a new aerosolizator OPTI JET MD 2ZE with nanosized
nozzle. The droplet size is now 10-15 microns, which is a key point of the simulation.
The obtained data will enable accurate calculation the maximum amount and
concentration of the use of biocide and it s possible toxic effects on staff and patients. After
completing the simulation analysis on the chamber simulation model, we will again perform
the aerosolization in the MRI 3T space and check the effectiveness of the disinfection in
difficult accessible locations, with the new aerosolizator OPTI JET MD 2ZE and
parameters from the simulation chamber analysis.
The use of EOW with the aerosolization method is suitable for use in MRI rooms. After
the disinfection no residuals are present on surfaces. Disinfection with aerosolozation of the
diagnostic equipment is possible after the procedure of each patient. However, due to the
large number of procedures, the personnel can be exposed to increased aerosol inhalation.
With increased number of diagnostic aerosolizations we were prompted to optimize the
method of aerosolozation and analyse the potnetial toxicity of EOW aerosol.