Principles of Radiation Biology and Protection in Dental Practice

This document discusses the principles of radiation biology and protection in dental practice. It covers different types of dental radiation, ways to protect dental staff from excessive radiation, and the stages of processing a dental X-ray film. The document also explains the purpose of components of an intraoral dental X-ray tube and provides information on reporting processing issues and film fog.

HLTDEN007 Apply the principles of radiation biology and protection in dental practice
Knowledge Questions v 1.3 (2017/09/06)
HLTDEN007 Apply the principles of radiation biology and
protection in dental practice
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Assessment
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Knowledge Questions
Carefully read through each question. Reflect on your learning for this unit and on your own
research. Please aim to present 180 words for each response so as to fully demonstrate your
knowledge in this area of study. A minimum of 150 words for each response is required.
Please note: Where the word count is not met, your submission will be returned to you for re-
working.
1. There are several different types of dental radiation. List each type and, in your own words,
provide an explanation of each.
(min 150 Words)
The different types of dental radiation are as follows:
Extraoral radiographs- They are prepared with films outside mouth and provide detailed
information on skull and jaws. They also monitor teeth development and growth.
Intraoral radiographs- These are one of the most common type of dental radiation are
provide a detailed visualisation of the teeth. These facilitate detection of cavities, tooth
rots, health of bony regions surrounding tooth, and monitoring good health of the teeth
(Intraoral 2018).
Panoramic X-rays- Help in visualising the entire mouth, including both upper and lower jaw,
and can be conducted with the help of a special machine.
Cephalometric projections- Cover the complete side of head and help in obtaining a picture
of the teeth, in relation to the individual’s profile and jaw.
Cone-beam computed tomography (CT)- Gives three-dimensional images and requires the
person to sit or stand, while the machine rotates around head (Iannucci and Howerton
2016).
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HLTDEN007 Apply the principles of radiation biology and protection in dental practice
Knowledge Questions v 1.3 (2017/09/06)
Standard computed tomography (CT)- Helps in determine the placement location and size
for dental implants.
2. How can dental staff be protected from excessive radiation at the workplace? List the key
points for protecting yourself, patients, and other staff. In your response, include the ALARA
principle.
(min 150 Words)
The employees conducting dental radiography should not be exposed to significant doses of
radiation, provided protection measures are adequately employed. The staff should not
hold dental films during radiography and should use portable X ray equipment, only for
diagnostic procedures that do not allow transferring patients to specific units. The effective
occupational dose must be maintained at 20 mSv per year, and all protocols must be
followed for determining the X-ray machine integrity and functioning of the panoramic
cassettes and digital image receptors (Ludlow et al. 2014). X-rays should not be taken prior
to preparation of the computer, in order to reduce unnecessary patient exposure to
radiation. Lead aprons should also be used while conducting vertex occlusal examinations
on pregnant patients. Three safety measures of ALARA principles that must be followed are
namely, (i) reducing time of exposure to radiation, (ii) doubling the distance between the
radiation source and body, which in turn will split radiation shielding exposure by factor of
4, and (iii) using absorber materials like lead for reducing exposure (Berkhout 2015).
3. There are many different factors affecting the radiation dose and several different ways of
measuring it. List and describe three different radiation doses.
(min 150 Words)
Three major factors that create an impact on radiation doses are intensity, length of
radiation exposure, and sensitivity of the skin. Three types of radiation doses are:
1. Absorbed dose that is generally used to measure the possibility for biochemical
variations in explicit tissues. This refers to concentration of energy set down in
tissue as a consequence of an ionizing radiation exposure. It is measured in milligray
(mGy).
2. Equivalent dose that is typically used to calculate how much biological impairment
is anticipated from the absorbed dosage (Dissimilar types of radiation have diverse
destructive properties). It refers to the quantity that takes the harmful properties of
diverse categories of radiation into consideration. It is measured in milliSievert
(mSv) (Thomson, Johnson and Johnson 2014).
3. Effective dose that is generally used to evaluate the probability for long-term
impacts that might be encountered in future. It is a calculated quantity, thereby
taking into consideration sensitivity of the dose, and measured in terms of mSv.
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HLTDEN007 Apply the principles of radiation biology and protection in dental practice
Knowledge Questions v 1.3 (2017/09/06)
4. List and describe the stages of processing a dental X-ray film. Bear in mind that the process
is similar irrespective of whether the film is processed manually or automatically.
(min 150 Words)
Most dentists who conduct manual processing expose the patients to radiation, with the
aim of saving time, thereby resulting in radiographs that have an inferior diagnostic quality.
The different types of processing methods are: (i) Manual processing, (ii) Automatic
processing (iii) Day Light processing and (iv) Self-developing films. The steps are:
 Exposure- Helps in latent image formation by ionisation of silver bromide crystals
with the help of photon energy, prior to commencement of processing. Exposure of
radiography results in a physical change and forms latent image by free silver ion
deposits.
 Development- Developer solution amplifies the latent image for creating a silver
pattern. The solution softens film emulsion and forms black metallic silver (James
2015).
 Rinsing- Conducted for 30 seconds in water for diluting the developer, removing
alkali activator and slowing development method.
 Fixing- Chemical solution added for removing unenergised and unexposed silver
halide crystals.
 Washing- Removes excess chemicals (James 2015).
 Drying- Films are dried in dust-free region, at room temperature, before mounting.
5. Briefly explain the purpose of the following components of an intraoral dental X-ray tube:
Cathode, Anode, Leaded glass housing, Collimator and PIO.
(min 150 Words)
1. Cathode- Helps in expelling electrons from circuit and later on focuses them in a
perfect beam, right at the focal spot located on the anode. Acts in the form of a
controlled electron source for generating X-ray beams.
2. Anode- Typically constructed from molybdenum or tungsten and has a window
designed with the sole purpose of generating X-ray photons. Has two major
functions namely, (i) converting electronic energy to X-ray radiation, and (ii)
dissipating heat generated during the process (Cosslett and Nixon 2014).
3. Leaded glass housing- This metal casing prevent leakage of ionising radiation and is
particularly filled with oil for dissipation of heat. Acts as a major shield and absorbs
radiation, except those that are passed through the window.
4. Collimator- It is a metal component that defines the shape and size of the X-ray
beam (He 2018).
5. PIO- This allows the beam to be accurately aimed at the zone under investigation,
besides predefining focus-to-skin distance.
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HLTDEN007 Apply the principles of radiation biology and protection in dental practice
Knowledge Questions v 1.3 (2017/09/06)
6. Why is reporting processing issues important? Whom do you report to, and what details do
you provide when reporting?
(min 150 Words)
Faulty radiographs might be obtained due to errors in the operation and functioning of the
machine, errors in film production technique, and errors in film processing and mounting.
The processing issues must be reported to the Radiation Safety Officer who will be
responsible for supervising the radiation protection, with the aim of minimising the errors in
processing. The regulatory authority must be consulted and liaised with, besides ensuring
that there is not light leak in the room. The report will contain use of correct form
(edentulous or dentate), complete demographics of the patient (full name, chart, date of
exposure), presence of light image, blank image, dark image, black spot, reticulation, white
spot, or yellow brown discolour (Elangovan et al. 2016). Film handling errors must also be
highlighted such as, developer cut-off, writing lines, finger nail artefact, or scratched film
(ARPNS 2015). The report should also highlight the presence of fixer cut off, smudge, or
static electricity.
7. In your own words, describe what is meant by film fog. List at least six possible causes of film
fog and, for each cause, explain how you would correct the fault.
(min 150 Words)
Film fog is a common reason of X-ray film artefact and can leads to deterioration in the
image quality. Six causes of film fog are as follows:
 If the chemical used for film processing becomes too strong or too hot- Maintain
the chemical at room temperature.
 Due to exposure of the radiographic film to high intensity visible white light- Reduce
intensity of the visible white light (Adejoh et al. 2014).
 If the dental radiograph film becomes too old, with an increase in age, fog might
appear- Not using radiographic films, past their expiration date.
 If the filter shows the presence of a crack or is not used accurately- Not exposing
the film to excessive humidity or heat during storage.
 If the wattage of the bulb used during developing or processing is too high or close
to the working zone (<5 feet)- Increasing distance from light source from the film.
 If light leaks into the darkroom- Preventing leakage of light into darkroom.
References
Adejoh, T., Onwuzu, S.W.I., Nkubli, F.B. and Ikegwuonu, N.C., 2014. Film-Screen
Radiographic Artefacts: A Paradigm Shift in Classification. Open Journal of Medical
Imaging, 4(3), p.108.
Australian Radiation Protection and Nuclear Safety Agency., 2015. Radiation Protection in
Dentistry. [online] Available at:
https://www.arpansa.gov.au/sites/default/files/legacy/pubs/rps/rps10.pdf
Berkhout, W.E., 2015. The ALARA-principle. Backgrounds and enforcement in dental
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HLTDEN007 Apply the principles of radiation biology and protection in dental practice
Knowledge Questions v 1.3 (2017/09/06)
practices. Nederlands tijdschrift voor tandheelkunde, 122(5), pp.263-270.
Cosslett, V.E. and Nixon, W.C., 2014. X-ray Microscopy. Cambridge University Press.
Elangovan, S., Mahabob, M.N., Jaishankar, S., Kumar, B.S. and Rajendran, D., 2016. Faulty
radiographs: A cross-sectional analysis among dental college students in Namakkal District,
Tamil Nadu, India. Journal of pharmacy & bioallied sciences, 8(Suppl 1), p.S116.
He, B.B., 2018. Two-dimensional X-ray diffraction. John Wiley & Sons.
Iannucci, J. and Howerton, L.J., 2016. Dental Radiography-E-Book: Principles and
Techniques. Elsevier Health Sciences.
Intraoral, X., 2018. X-RAY FILM Composition. White and Pharoah's Oral Radiology:
Principles and Interpretation, p.60.
James, C., 2015. The book of alternative photographic processes. Cengage Learning.
Ludlow, J.B., Timothy, R., Walker, C., Hunter, R., Benavides, E., Samuelson, D.B. and
Scheske, M.J., 2014. Effective dose of dental CBCT—a meta analysis of published data and
additional data for nine CBCT units. Dentomaxillofacial Radiology, 44(1), p.20140197.
Thomson, E., Johnson, O. and Johnson, O.N., 2014. Essentials of Dental Radiography.
Pearson.
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