Xray - Outcome 2 Flashcards
ALARA principle
The ALARA (“as low as reasonably achievable”) concept states that all exposure to radiation must be kept to a minimum. To protect both patients and operators, every possible method of reducing exposure to radiation should be employed to minimize risk. The radiation protection measures detailed in this chapter can be used to minimize patient and operator exposure, thus keeping radiation exposure “as low as reasonably achievable (Iannucci & Howerton, 2022) .”
Three personal monitoring devices of x-radiation are the:
Film badge – a badge that is to be clipped on the body as per the manufacturer’s direction
Pocket dosimeter – usually the size of a pen and can be read by the person wearing it
Thermo luminescent devices (LTD) – come in various forms; based on crystals that are energized through x-radiation that give off light when heated (Robinson, 2024).
Film Badge
The film badge is the most common type of monitoring system used. The badge is labeled and tracked through your social insurance number. It consists of an x-radiation-sensitive receptor with varying levels of sensitivity which records exposure (Robinson, 2024). On regular intervals, at the end of the reporting period, the badge is sent in to be read. These results are compared to the previous reports and are kept on file at the monitoring service company. A copy of this report is forwarded back to the dental office.
In the Province of Alberta, all professionals who participate in radiological procedures are required to wear a personal dosimeter (Alberta Government, 2021). Quality control procedures for equipment will be discussed later.
2 biological effects of x-radiation
The biological effects can be identified as somatic or genetic
Somatic
Somatic is exposure to radiation that causes a direct effect. Meaning the effect is not passed on to future generations. This is causing an effect on the irradiated cells in the body except for the reproductive cells (Iannucci & Howerton, 2022).
Injury to the individual
Reddening of the skin, pigmentation of the skin
Scales or ulcerations
Nausea, vomiting, diarrhea
Loss of hair
Cataracts
Cancer
Leukemia
Life-span shortening
Genetics
Genetics is the changing of the reproductive cells through radiation exposure. These changes can be transferred to succeeding generations via reproductive cells (sperm/ova).
Injury to future generations
Radiation-induced mutations
latent period
the time lag between the radiation exposure and the signs and symptoms of biological damage
Risk versus Benefit Concept - for x-radiation
Risk versus Benefit Concept
There are some risks associated with the use of imaging radiation in dentistry. However, the levels of radiation involved in dental radiography are very low and are directed to a much-localized area. The benefit of detecting disease, which might otherwise go undetected, far outweighs the risk of receiving a small dose of x-radiation (Iannucci & Howerton, 2022). Next to the elimination of unnecessary X-ray examinations, the most significant factor in reducing patient dose is ensuring that examinations are performed using the proper technique. It is the responsibility of the dental assistant and the prescribing dental practitioner to be aware of this and to know how to carry out a prescribed examination with the lowest practical dose for the patient (Health Canada, 2022). The supervising professional is responsible for evaluating each patient’s needs when exposing radiographs.
Protection for the Patient during xrays
A dental assistant must not perform any X-ray procedures unless it has been prescribed by the prescribing dental practitioner responsible for the patient (Health Canada, 2022).
The dental X-ray examination of a patient should be based on the history and clinical evaluation of the patient and should be to obtain diagnostic information, provide safe and efficient treatment, or monitor patient treatment (Health Canada, 2022).
Routine or screening examinations using dental X-rays, in which there is no prior clinical evaluation of the patient and no clinical justification, should not be performed, including examinations of children to monitor dental development. Dental X-ray examinations should only be performed after a clinical examination of the patient has determined an expected health benefit to the patient (Health Canada, 2022).
The possibility of performing non-radiographic examinations should first be considered. It should be confirmed that no previous X-ray images are available, which would avoid additional X-ray exposures (Health Canada, 2022).
The number of radiographic views required in an examination must be kept to a minimum, consistent with the clinical objectives of the examination
The dose to the patient must be kept to the lowest practical value, consistent with clinical objectives, and without loss of essential diagnostic information (Health Canada, 2022).
If there are selectable image resolution settings, for each image the lowest possible resolution setting that will meet the clinical objective should be used, as this can significantly reduce the dose received by the patient (Health Canada, 2022).
Radiological examinations of children must be performed using optimized techniques that have been modified for size and age (Health Canada, 2022).
Dental X-ray equipment must be maintained and monitored routinely through a Quality Assurance program and preventative maintenance, including routine monitoring of the quality of radiographs to ensure that they satisfy diagnostic requirements with minimal radiation exposure to the patient (Health Canada, 2022).
All images captured, whether on film or digital imaging systems, must remain with the patient records unless they are rejected by the operator for valid predefined quality issues. All rejected images must be collected for use during routine rejection/retake analysis (Health Canada, 2022).
Pregnant or possibly pregnant persons - xray safety
Full consideration must be taken of the consequences of fetal irradiation.
It is generally accepted that the level of radiation to the fetus from dental X-rays is extremely low when the abdomen is not directly exposed (Health Canada, 2022).
For dental X-rays of pregnant patients, the Canadian Dental Association states that “Elective procedures may be deferred until after the pregnancy. Pregnant patients requiring essential and/or emergency treatment should receive the minimum number of radiographs needed for diagnostic purposes ” (Canadian Dental Association, 2005).
Lead apron and thyroid collar use
Lead apron and thyroid collar use
The use of a thyroid shield is especially important in children, as the thyroid gland in children is particularly sensitive to radiation (Health Canada, 2022).
The patient must be provided with a thyroid shield when it will not interfere with the required diagnostic information for the examination (Health Canada, 2022).
The use of a lead apron is not required for the patient during routine dental X-ray procedures if all other recommendations for limiting patient radiation exposure are respected as the dose to the patient will not be significantly affected by abdominal shielding; however, a lead apron may be used to aid in patient comfort regarding fears of radiation (Health Canada, 2022).
Collimation
Collimation
The X-ray beam must be well collimated and aligned with the patient’s head to restrict the beam as much as practicable to the area of diagnostic interest.
Rectangular collimation of the X-ray beam must be used for intra-oral examinations, except in occlusal protocols, as it significantly reduces the dose to the patient compared to circular collimation (Health Canada, 2022).
Intra-Oral Examinations
A film/image receptor holder with an alignment device for the X-ray beam should be used (Health Canada, 2022).
A long cone (30 cm or longer) should be used, as it reduces the dose to the patient compared to a short cone (20 cm). The cone must ensure a minimum focal spot-to-skin distance of 20 cm (Health Canada, 2022)
For film-based imaging when the implementation of digital radiography is not practicable, E-speed film or faster must be used, and D-speed film must not be used (Health Canada, 2022).
Protection for the Operator
any measure taken to protect the patient also protects the operator, but there are some “special” precautions to be observed by the operator.
Never hold films in the patient’s mouth during exposure.
Never stand in the direct path of the X-rays.
Stand as far as possible, at least 6 feet, from the source of radiation.
Never stay in an operatory to stabilize the tube head or PID during exposure.
Lead-lined walls and specially constructed partitions or lead screens afford excellent protection for the operator.
Utilize personnel monitoring devices for all staff members (dosimeter badges).
Routinely check all radiographic equipment to prevent “trouble” before it happens (quality assurance).
A periodic on-site survey will determine the output of the x-ray unit, radiation leakage, or any dangerous area by qualified radiation protection personnel.
maximum permissible dose (MPD)
The most recent NCRP report states that the current MPD for occupationally exposed persons, or those who work with radiation (e.g., dental radiographers), is 50 mSv/year (0.05 Sv/year or 5.0 rem/year). It is recommended that dental radiographers not exceed a maximum dose of 50 mSv in any 1 year. For pregnant dental personnel, the radiation exposure limit is 0.5 mSv per month during the pregnancy months. For nonoccupationally exposed persons (i.e., the general public), the current MPD is approximately 1 mSv/year (0.1 rem/year).
