1.5: Cleaning and disinfection of radiology setup

Binit Sureka

One, who maintains cleanliness keeps away disease.

Sam Veda

Introduction

In India, there are approximately about 100,000 ultrasound machines, 6000 computed tomography (CT) scans and around 1500 magnetic resonance imaging (MRI) machines, and in the next 10 years, the number is going to double. Disinfection and sterilization are essential components in day-to-day running of the hospital so that equipment does not transmit infectious pathogens to the patients. Cleaning and disinfecting activities in hospitals are critical for preventing healthcare-associated infections. This chapter would highlight the effects of infectious diseases on the imaging equipment, with consideration of guidelines from various international and national advisory boards. Few basic rules that need to be followed are listed in the following:

• Housekeeping staff should wear adequate personal protective equipment (PPE).
• For highly infectious diseases, wear triple layer surgical mask, disposable gown, gloves, shoe cover, disposable cap, goggles while cleaning and disinfecting the facility.
• Always switch the system off at the main power switch before cleaning or disinfecting.
• Follow manufacturer’s instructions for application and proper ventilation.
• X-ray and ultrasound systems should be covered with two layers of fluid-impermeable plastic.
• Alcohol solutions should contain ≤70% alcohol.
• Never mix household bleach with ammonia or any other cleanser.
• Do not shake dirty laundry.
• Wash hands with soap and water as soon as you remove the gloves.
• An alcohol-based hand sanitizer that contains at least 60% alcohol should be used.
• While disinfecting facilities, care should be taken for adequate air circulation. Ensure at least 10–15 air exchanges per hour.
• The air-conditioning units (for the examination room) should be switched off.
• The equipment in the room should be covered with plastic coverings, and any vents should be sealed with leak-proof tape.
• The equipment should not be used for at least 30–60 min after disinfection depending upon the chemical used.
• All instructions in the operator manual regarding cleaning and, when applicable, regarding disinfecting and sterilization must be always observed. Also read all the instructions written on each disinfectant and cleansing bottle.

It is important to be aware of the various chemical disinfectants available for cleaning (Fig. 1.5.1). The various agents available are listed in Table 1.5.1.

TABLE 1.5.1

Agents Used for Cleaning and Disinfection

Cleaning Agents	Purpose and Mechanism of Action	Options
Aldehyde	Acts against bacteria, bacterial spores and viruses – by altering the nucleic acids and protein synthesis.	Glutaraldehyde Formaldehyde Paraformaldehyde Cidex
Quaternary compounds	Acts against the lipophilic viruses – by inactivating enzymes and disrupting the cell membrane.	Alkyl dimethyl benzyl and ethylbenzyl ammonium chloride Didecyl dimethyl ammonium chloride
Alcohol	Acts by breakage of hydrogen bonds within the proteins.	Ethyl alcohol (70%)
Chlorine derivatives	Acts by disruption of the DNA synthesis.	NaDCC (sodium dichloroisocyanurate) Sodium hypochlorite (“bleach”) Calcium hypochlorite
Benzene	Acts on spores by blocking the spore germination process.	Ortho-phthalaldehyde
Alkylamines	Acts on fatty acids.	Mono/triethanolamine Ortho-phenylphenol Ortho-benzyl-para-chlorophenol Hexachlorophene–pHisoHex Chlorhexidine Lysol
Phenol derivatives (0.5%–3%)	Acts by disrupting the cell wall and precipitating the cell proteins.
Organic acids	Disrupts the cell wall permeability.	Carboxylic acid, acetic acid
Peroxide compounds	Acts by producing hydroxyl free radicals.	Hydrogen peroxide (3.0%–6.0%)
Guanidine compounds	Bactericidal and fungicidal.	Polyhexamethylene guanidine

Cleaning and disinfection of facility

• Radiology reporting rooms, office spaces, waiting areas and teaching rooms should be cleaned after or before the rooms are occupied.
• Prior to cleaning, adequate protective equipment such as disposable rubber boots, gloves (heavy duty) and a triple-layer mask should be worn.
• All indoor areas should be mopped with a disinfectant.
• After imaging of a highly infectious patient, high contact surfaces such as public counters, intercom systems, equipment such as telephone and printers/scanners and other office machines should be cleaned at least three to four times daily by mopping with high-level disinfectant solution.
• Frequently touched areas should specially be cleaned.
• Metallic surfaces should be cleaned by 70% alcohol.
• Hand sanitizing stations should be installed in office premises (especially at the entry) and near high contact surfaces.