RADIATION PROTECTION
DR. IESHA LAPUN
TEACHING FELLOW
UNIVERSITY OF PAPUA NEW GUINEA
AIMS AND OBJECTIVES
By the end of this session students should be able to:
Know and explain the factors associated with radiation protection
of patients
Know and explain the factors associated with radiation protection
of the general public
Know and explain the factors associated with radiation protection
of radiation workers/operators of equipment
Introduction
Many of the early pioneers in dental radiography suffered from the
adverse effects of radiation.
The hazards of radiation are now well documented, and radiation
protection measures can be used to minimize radiation exposure for
both the dental patient and the dental radiographer as well as the
general public.
Radiation Protection for Patients
The main radiation dose to patients comes from:
Being irradiated in the first place, which is totally dependent on the
decision and clinical judgement of their dentist
The main beam of the X-ray equipment.
The main practical radiation protection measures for patients can
therefore be considered under three headings:
Clinical judgement
Equipment
Radiographic technique and the technical skill of the staff
undertaking the radiography.
CLINICAL JUDGEMENT
All dentists must have received adequate training in dental
radiology and should undertake continuing education and training
after qualification to keep their knowledge and skills up to date,
particularly in relation to the clinical applications of new
technology, e.g. cone beam CT (CBCT).
This seems reasonable as it is the dentist who decides on the
acceptability of the risk to which the patient is being subjected.
Every exposure should be justified on the grounds of:
The availability and/or findings of previous radiographs
The specific objectives of the exposure in relation to the history and following
clinical examination of the patient
The total potential diagnostic benefit to the patient
The radiation risk associated with the radiographic examination
The efficacy, benefits and risks of alternative techniques having the same
objective but involving no or less exposure to ionizing radiation.
EQUIPMENT
All dental X-ray generating equipment should;
Be installed correctly and tested by a medical physicist for safety and output
before being used on a patient
Be checked regularly by a medical physicist, for e.g. every 1–3 years
Function within agreed parameters – (Voltage,amperes etc)
Contain adequate filtration
Have the main beam collimated to cover the rectangular image receptor
Have an exposure switch (timer) that only functions when continuous pressure is
maintained and that terminates if pressure is released
Be provided with film speed controls and finely adjustable exposure time setting
Radiographic technique and technical skill
of staff undertaking the radiography.
Staff should undertake radiography accurately to avoid retakes, for
example by using image receptor holders and beam aiming
devices for intraoral radiography
Use the minimum number of projections
Ensure all image processing (chemical or computer) is carried to the
highest standards so that images do not have to be retaken
Thyroid collars should be used in those few cases where the thyroid
may be in the primary beam
Protective aprons, having a lead protective layer should be
provided for all patients and any adult who provides assistance by
supporting a patient during radiography
When a lead apron is provided, it must be correctly stored
If a patient is known to be pregnant then the patient should be
reassured that the developing foetus may be at high risk. Delay
radiographic examination if possible.
RADIATION PROTECTION OF
GENERAL PUBLIC
This group includes everyone who is not receiving a radiation dose
either as a patient or as a radiation worker, but who may be
exposed inadvertently, for example, someone in a dental surgery
waiting room, in other rooms in the building or passers-by.
The general public is at risk from the primary beam, so specific
consideration should be given to:
The siting of X-ray equipment to ensure that the primary beam is not
aimed directly into occupied rooms or corridors
The thickness/material of partitioning walls
RADIATION PROTECTION OF RADIATION
WORKERS / OPERATORS OF EQUIPMENT
The radiation dose to dentists and their staff can come from:
The primary beam, if they stand in its path
Scattered radiation from the patient if they stand too close
Radiation leakage from the tubehead
The main practical radiation protection measures include:
Ensuring all radiation workers (dental staff) know the risks to their own
health created by exposure to X-rays and the safety precautions
they need to take
Always standing outside the so-called controlled area
approximately 1.5 m from the X-ray machine and the patient (or
behind appropriate lead screens/barriers) and never in the path of
the main beam
Never holding an image receptor in a patient’s mouth
Never holding the X-ray tube head during an exposure
Always using the X-ray equipment safely and in accordance with
current guidance and good practice
MONITORING
The amount of radiation received by individuals can be monitored
and measured using a variety of different monitoring devices and
can include:
Film badges
Thermoluminescent dosimeters (TLD)
• Badge
• Extremity monitor
Optically stimulated luminescence dosimeters (OSLD)
Personal electronic dosimeters (PED).
DENTAL RADIOGRAPHY –
GENERAL PATIENT CONSIDERATIONS
AND INFECTION CONTROL
AIMS/ Objectives
By the end of this session. Students should be able to;
To know and explain the general guidelines on patient care for oral
radiography
To know and explain the rationale for infection control in oral
radiography
GENERAL GUIDELINES FOR PATIENT
CARE WHEN TAKING RADIOGRAPH
For intra oral radiography, patient should be positioned comfortably
in the dental chair, ideally with the occlusal plane horizontal and
parallel to the floor
- Head should be supported against the chair to minimize unwanted
movement
For extraoral views the patient should be reassured about the large,
possibly frightening or unfriendly-looking equipment, before being
positioned within the machine. This is of particular importance with
children.
The procedure should be explained to the patients in terms that
they can understand, including warning them not to move during
the investigation.
Spectacles, dentures or orthodontic appliances should be removed.
Jewellery including earrings may also need to be removed for
certain projections.
A protective lead thyroid collar, if deemed appropriate for the
investigation being carried out, should be placed on the patient.
The exposure factors on the control panel should be selected
before positioning the intraoral image receptor and X-ray tube
head, in order to reduce the time of any discomfort associated with
the investigation.
Intraoral image receptor should be positioned carefully to avoid
trauma to the soft tissues. Care should be taken particularly in tissues
such as the anterior hard palate, lingual to the mandibular incisor
teeth and disto-lingual to the mandibular molars
The radiographic investigation should be carried out as accurately
and as quickly as possible, to avoid having to retake the radiograph
and to lessen patient discomfort.
The patient should always be watched throughout the exposure to
check that he/she has obeyed instructions and has not moved.
SPECIFIC REQUIREMENTS WHEN X-RAYING CHILDREN
AND PATIENTS WITH DISABILITIES
Neurological disabilities, such as:
These two groups of patients can
present particular problems during - Communication and learning
radiography, including: difficulties
Difficulty in obtaining cooperation - Tremor
Anatomical difficulties, such as: - Palsy.
– Large tongue (macroglossia)
– Small mouth (microstomia)
– Tight oral musculature
– Limited neck movement
– Narrow dental arches
– Shallow palate
– Obesity
As a result of these difficulties, the following additional guidelines
should be considered:
Only radiographic investigations appropriate to the limitations
imposed by the patient’s age, cooperation or disability should be
attempted
Select intraoral image receptor of appropriate size, modifying
standard techniques as necessary.
Utilize assistant(s) to help hold the image receptor and/or steady
and reassure the patient. This can be accomplished by using an
accompanying relative, rather than repeatedly using a member of
staff.
INFECTION CONTROL
RATIONALE FOR INFECTION CONTROL
primary purpose of infection control procedures is to prevent the
transmission of infectious diseases
Infectious diseases may be transmitted from a patient to the dental
professional, from the dental professional to a patient, and from one
patient to another patient
The use of recommended infection control guidelines can greatly
reduce the transmission of infectious diseases
In the dental environment, the general routes of disease transmission
can be described as follows:
Direct contact with pathogens present in saliva, blood, respiratory
secretions, or lesions.
Indirect contact with contaminated objects or instruments
Direct contact with airborne contaminants present in spatter or
aerosols of oral and respiratory fluids
For an infection to occur by one of these routes of transmission, the
following three conditions must be present:
1. A susceptible host
2. A pathogen with sufficient infectivity and numbers to cause
infection
3. A portal through which the pathogen may enter the host
Effective infection control practices are intended to alter one of
these three conditions, thereby preventing disease transmission
Dental radiography is not an invasive procedure and is generally
considered low-risk for the operator, except when blood is present,
e.g. post-extraction, post trauma.
Since saliva and/or blood can contaminate films and radiographic
equipment, meticulous cross-infection control is important
The radiographer should wash his/her hands before and after each
examination within sight of the patient.
If the operator has any open wounds on the hands, these should be
covered with a dressing.
Hospital policies vary on the need for gloves to be worn routinely
during intra-oral radiography.
Barrier envelopes for intra-oral films significantly reduce the risk of
microbial contamination by saliva and/or blood.
If barrier envelopes are not available, then exposed film packets
should be disinfected before they are handled and processed.
The use of a disposable tray system containing film packets and film
holders significantly reduces contamination of work surfaces.
Contaminated empty film packets, barrier envelopes, gloves,
cotton-wool rolls and disposable tray should be discarded as clinical
waste.
Intra-oral film-holding devices should be sterilized according to the
manufacturer’s guidelines. Most manufacturers recommend rinsing
and steam autoclaving after use. Some film holding devices are
disposable
Surface disinfectants should be used on all work surfaces, the dental
chair, cassettes, the control panel, the X-ray tube head and the
exposure switch after each patient.
Manufacturers of panoramic equipment may provide individual bite
blocks or disposable bite-block covers for each patient. The former
are sterilized, whilst the latter are discarded after exposure. Chin
rests and head-positioning guides should be cleaned between
patients.
Manufacturers provide disposable barrier envelopes for the sensor in
digital imaging systems. The mouse and the keyboard of computers
are a potential weak spot in cross-infection control. If you feel that
there is a risk from oral fluids, then you should protect these items
SUMMARY
The main practical radiation protection measures for patient is
considered under three headings:
Clinical judgement
Equipment
Radiographic technique and the technical skill of the staff
undertaking the radiography.
General guidelines for patient care when taking radiographs must
be followed.
References
Frommer, H., Stabulas-Savage, J. RADIOLOGY FOR THE DENTAL
PROFESSIONAL. 9th edn. 2011. Elsevier.
Fuhrrmann, A. DENTAL RADIOLOGY. 2015. Thieme.
Whaites, E., Drage, N. Essentials of Dental Radiography and
Radiology. 5th edn. 2013. Elsevier.
