Canon Medical Systems USA

The Medical Imaging Technologist's Role In Infection Control

Erica C. Schuster Rieffanaugh, RT(R)(CT) - eRADIMAGING | March 27, 2020

This article has been provided courtesy of Canon Medical's Education Partner, eRADIMAGINGClick here to learn more about eRADIMAGING.

Medical imaging is an invaluable tool that aids clinicians in the diagnosis of many patient ailments. Although radiologic technologists are acutely aware of the many technical factors involved in obtaining images, they also need to consider that most patients undergoing medical imaging may have a pathologic or infectious disease. Proper disinfecting, cleaning, and sanitizing of the equipment being used (according to the healthcare facility's policies and procedures) is essential after each patient's examination is completed, even for patients who are considered healthy.

As a medical imaging professional, it is important to ALWAYS follow standard infection control precautions when handling someone's blood, bodily fluids, or items that are soiled with blood or bodily fluids, in addition to following strict hand hygiene practices. Standard precautions include performing hand hygiene and wearing personal protective equipment for each patient. Pathogens are spread by many different means. Some are spread through direct contact, indirect contact, or through droplets.

Because healthcare facilities are continually updating their plans for how to address infectious patients, particularly those with potential new infectious conditions/pathogens, it is important for medical imaging professionals to remain updated on isolation/infectious patient protocols and apply them to daily imaging. Healthcare professionals frequently encounter patients who have not yet received diagnoses on their presenting conditions, and thus have a prominent effect on infectious processes, specifically in reducing the rate of transmissibility. This article's purpose is to inform the medical imaging professional of the means by which infectious pathogens are spread by infected blood and bodily fluids, and to highlight some of the infections that can be encountered on a day-to-day basis when working in a healthcare environment.

Disease Processes
Microorganisms are common and present everywhere. Those that are capable of causing disease are called pathogens. Most microorganisms do not cause diseases; in fact, many provide some protection against harmful microorganisms.1

The term disease refers to conditions that impair normal tissue function. The terms "infectious" and "disease" are not synonymous, as disease processes exist that are both infectious and noninfectious in nature. An example of a noninfectious disease is coronary atherosclerosis, the narrowing and hardening of arteries that supply blood to the heart. This disease is internalized in the patient and cannot be passed on to someone else.2

An infection occurs when a pathogen invades and begins growing within a host. To cause disease, pathogens must be able to enter the host body, adhere to specific host cells, invade and colonize host tissue, and inflict damage on those tissues.1 A healthy immune system provides protection against invading pathogens. People with weakened immune systems are more susceptible to disease; these patients include the very young, the elderly, patient with cancer who are receiving chemotherapy, and individuals who are human immunodeficiency virus (HIV)-positive or have acquired immunodeficiency syndrome (AIDS).

There are 2 types of disease processes: pathologic and infectious. Pathologic processes occur within a single patient and cannot be transmitted from patient to caregiver or patient to patient. Infectious processes associated with pathologic processes or that result from pathologic processes can be transmitted. An example of the difference between pathologic and infectious processes would be a viral or bacterial pneumonia that is transmitted from a patient with cancer. Cancer would not be transmitted from patient to patient and is an example of a pathologic process; the pneumonia is an example of an infectious process, which can be transmitted.3
Following isolation instructions, proper hand hygiene, and infection control processes will significantly reduce the healthcare worker's chances of becoming infected, as well as reduce the chances that these infections will be transmitted from patient to patient.

Virulence, Transmissibility, and Pathogenicity of Infectious Disease Processes
Infectious disease pathogens enter the body in different ways. The host may not always suffer, even though cells may be affected. Virulence is the ability of a pathogenic virus to cause a serious disease. The level of sickness or disease the infection causes can be very mild and almost undetectable, to very serious and deadly.
The ability to pass an infectious pathogen from one person to another is known as transmissibility. Some viruses are easily transmitted (eg, influenza), while others are not (eg, HIV). Viruses typically enter the host via natural orifices, such as the mouth, eyes, or genital openings. Other points of entrance include the skin, through cuts or needle sticks. Infectious agents may be transmitted by either direct or indirect contact. Direct contact occurs when an individual is infected by contact with the reservoir (the site where the infectious agent survives). In a hospital environment, the patient is usually the reservoir. Animals often serve as reservoirs for diseases that affect humans. Transmission by direct contact may occur by touching an infected person, inhaling the infectious agent in droplets (1)(which are emitted by sneezing or coughing), and through sexual contact. Indirect contact occurs when a pathogen can withstand the environment outside of a host (ie, the living being that is infected) for a period of time before infecting another individual (eg, a pathogen on an X-ray cassette, countertop, or doorknob).

Pathogenicity is the ability of a bacteria or virus to cause disease in a host organism. When the pathogens enter the host body, microorganisms can cause limited infections that the body can overcome on its own. However, medical intervention is needed when the pathogens causes infections that the body is unable to fight effectively. Identifying the pathogens is important as it helps the care providers identify the mode of transmission and break the cycle of transmission. Controlling the spread of pathogens leads to fewer infections of healthcare workers and patients.

Modes of Transmission
There are 6 modes by which infections are transmitted and corresponding ways of controlling their spread. According to the Centers for Disease Control (CDC) and the World Health Organization (WHO), all infections are spread by means categorized under these modes of transmission.4,5 The necessary precautions vary with the microorganism and the context of the illness.

The first 3 modes involve contact: direct, indirect, and droplet contact. Direct physical contact is body surface to body surface contact between the infected individual and the susceptible host.4 Indirect contact occurs when an infectious agent is deposited onto an object or surface otherwise known as a fomite, and survives long enough to transfer to another person who subsequently touches the item. Infectious agents can also be spread through droplet contact via coughing or sneezing and in a healthcare environment during suctioning. Droplets are relatively large and can be projected up to 1 meter.

Non-contact contamination comprises the last 3 modes: airborne without direct contact (through air ventilation without a host present), contact with a single contaminated source (vector), and transmission by insect or animal (animal bites). Airborne transmission takes place via aerosols that contain organisms in droplet nuclei or in dusts and can be spread via ventilation systems without direct contact with the host. Examples include tuberculosis (TB), measles, chickenpox, smallpox, and controversially, influenza. Contact with a single contaminated source that spreads the infection is known as vehicle contact. These include point sources such as foods or water sources that spread Escherichia coli, or an X-ray image receptor that has the potential to spread bacterial or viral pneumonia or other viruses and bacteria (6). Transmission by an insect or animal is called vector-borne contact.5

Prevention of Infectious Diseases
Infectious diseases can be prevented at a variety of points depending on the infectious cycle for the particular disease. In Figure 1, step 1, a host is infected by the reservoir, or vector for the pathogen.1 The infected individual may infect (step 2) other hosts in a population or (step 3) new vectors.3 The pathogen may also cycle between a vector and a reservoir. Understanding the infectious cycle is important in order to identify accessible targets for control strategies. You cannot control the instance of disease unless you understand the process and how to break the cycle of transmission.

Hospital-acquired infections (HAI) or nosocomial infections are infections that result from treatment in a hospital or healthcare unit. The most common modes of transmission are from staff to patients, from equipment to patients, or from patients to patients.5 Person-to-person transmission may be inhibited by proper hand hygiene and sanitary conditions. In a healthcare setting this is outlined by the CDC as hand hygiene and glove use.5 Next to your own intact skin, gloves are the first line of defense against potentially infectious agents for medical imaging technologists and patients. Patient-to-patient transmission of organisms that cause disease can occur through direct or indirect contact via the hands of healthcare workers or through contaminated patient-care equipment or environmental surfaces.1

Gloves, when used properly, will protect the wearer against infectious agents that could be present on the patients. When wearing gloves, it is important to recognize surfaces that are touched and to disinfect those surfaces between patients. Glove use presents a risk of cross-contamination when gloves are used inappropriately, and they are not enough to prevent the transmission of pathogens in healthcare settings. Hand hygiene must be performed before and after glove use to be effective.

Healthcare workers must also pay strict attention to isolation and infection control procedures, use sterile techniques appropriately, and wash their hands before and after contact with each isolation patient every time. All equipment must be properly cleaned, disinfected, and sterilized.6 Single-use equipment cannot be reused. Environmental measures such as proper cleaning and ventilation, good spacing of beds in patient care units, use of private rooms, private restroom facilities, and cleaning of patient waiting areas reduces the chances of infections spreading. Separating sterile and unsterile areas also contributes to a reduction in the ability for infections to be transmitted.4

Diagnostic imaging technologists in particular must take certain steps to end the transmission of disease from one patient to another each time an imaging procedure is performed. Proper hand hygiene, use of gloves, and wiping down equipment with disinfectants after every patient are important steps to follow but in many situations may not be the only steps that are necessary. Certain bacteria or viral infections require donning gowns, hazardous material suits, respirators, isolation masks, and cleaning equipment with specific chemicals. It is important to know which bacterial or viral infections require use of protective measurements above the hospitals standard precautions.

Portable Equipment
Portable equipment includes portable X-ray and ultrasound machines, image receptors, lead markers, and lead aprons. Being able to perform diagnostic imaging using portable equipment is a useful medical imaging tool. This type of equipment can be taken to isolation rooms when patients are being isolated for infectious disease processes. The equipment is then moved from patient room to patient room throughout the hospital, entering both infectious and noninfectious patient rooms. Bacterial and viral contamination is present on image receptors and equipment after being exposed to infectious patients. Without proper cleaning and disinfecting, these types of equipment can spread pathogens throughout the healthcare facility. The equipment must be cleaned, adhering to the healthcare facility's policies and procedures after imaging is completed. Strict attention must be given to all areas of the imaging equipment regardless of diagnosed or suspected infections to ensure that all surfaces that the technologist and patient came in contact with are cleaned and disinfected after each and every patient.

Placing image receptors in a protective bag is an effective way of protecting the patient from pathogens that may be on the image receptor itself. For the technologist, wearing gloves is an effective method of protection. Special attention must be taken to clean the equipment as the patient is often touched with gloved hands and then the equipment is touched with the same gloved hands, thus transferring the pathogen from the patient to the equipment. Even if protective bags are used, the equipment must always be cleansed and disinfected after every single patient encounter.

There are many possible modes of transmission of infectious diseases within healthcare facilities. Portable equipment, imaging tables, magnetic resonance imaging bore and table, computed tomography bore and couch, pillows, mattresses, sheets, blankets, patient beds, hover mats, Slip sheets, and back boards have the capability of harboring pathogens and are used by multiple healthcare providers and patients on a daily basis. All equipment must be disinfected after patient contact regardless of suspected or known infectious disease. Medical imaging staff encounter many patients during the day and by following facility protocols and procedures regarding cleaning and disinfecting, they have the ability to reduce the transmission of pathogens from patient to patient and from patient to caregiver.

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*Diagnostic Imaging Technologist, Harrison Medical Center, 2520 Cherry Ave, Bremerton, WA 98310.
Address correspondence to: Erica C. Schuster Rieffanaugh, RT(R)(CT), Diagnostic Imaging Technologist, Harrison Medical Center, 2520 Cherry Ave, Bremerton, WA 98310.

Disclosures: Ms Rieffanaugh reports having no significant financial or advisory relationships with corporate organizations related to this activity.
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