Orthodontic Radiograph guidelines By Issacson, 2007 Damaging effects on human tissue are currently divided into three major categories: 1. Somatic deterministic (certainty) effects when the threshold dose reached a. Direct effects: abnormal mitosis; degeneration and death of cells b. Indirect effects: change in tissue due to damage to blood supply (endarteritis) c. Constitutional effects: malaise, nausea, vomiting, decrease blood pressure, peripheral vascular failure (radiation shock) 2. Somatic stochastic (random) effects: Neoplastic change: e.g. skin, bone sarcomas, leukaemia 3. Genetic stochastic (random) effects, effect shown in offspring of recipient NB: Unnecessary radiation from diagnostic R/Gs causes 100-250 UK cancer fatalities. 25% of all X-ray examinations are dental The main effect of x-ray is by ionization. When an electron passes through a cell, it releases its energy along its path (called a track) by interacting with the electrons of nearby
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Orthodontic Radiograph guidelines
By Issacson, 2007
Damaging effects on human tissue are currently divided into three major categories:
1. Somatic deterministic (certainty) effects when the threshold dose reached
a. Direct effects: abnormal mitosis; degeneration and death of cells
b. Indirect effects: change in tissue due to damage to blood supply (endarteritis)
c. Constitutional effects: malaise, nausea, vomiting, decrease blood pressure,
peripheral vascular failure (radiation shock)
2. Somatic stochastic (random) effects: Neoplastic change: e.g. skin, bone sarcomas,
leukaemia
3. Genetic stochastic (random) effects, effect shown in offspring of recipient
NB:
Unnecessary radiation from diagnostic R/Gs causes 100-250 UK cancer fatalities.
25% of all X-ray examinations are dental
The main effect of x-ray is by ionization. When an electron passes through a cell, it releases its
energy along its path (called a track) by interacting with the electrons of nearby molecules. The
released energy is absorbed by atoms near the track, resulting in either excitation (a shift in the
orbit of an electron to a higher energy level) or ionization (release of an electron from the atom).
There are currently two sets of legislation in the UK, based on European directives,
following international community of radiation protection (ICRP) recommendation is,
namely:
1. The Ionising Radiations Regulations 1999 (IRR) which are primarily concerned with the
safety of worker and the general public.
2. The Ionising Radiation (Medical Exposure) Regulations 2000 (IRMER) which are
concerned with the protection of patients.
Essential legal requirements of IRR 1999
1. The Health and Safety Executive must be notified the routine use of dental X-ray
equipment.
2. A prior risk assessment must be undertaken before radiography commences and be
subject to regular review.
3. X-ray equipment, particularly all safety features, must be maintained.
4. A `controlled area' should be designated around each piece of X-ray equipment.
5. Local Rules are required.
6. A Radiation Protection Adviser (RPA) and a Radiation Protection Supervisor (RPS) must
be appointed and consulted.
7. All employees have and should be aware of their specific duties and responsibilities.
8. Information, instruction and training must be provided for all staff.
9. A quality assurance programme is required.
10. There is an over-riding requirement to restrict radiation doses to staff and other persons
as low as reasonably practicable (ALARP).
The IRMER includes three important measures:
A. Justification
B. Optimization (keeping the dose as low as possible ALARP with high benefit to the pt.by
increase KV, digital sensitive film, fast speed film, collimator , film holder, staff training,
quality assurance)
Essential legal requirements of IRMER 2000
New positions of responsibility are defined:
1. The Employer (Legal Person)
2. The Referrer
3. The Practitioner
4. The Operator
IRMER Employers
They are responsible for providing
The overall safety and radiation protection framework
Ensuring that staff and procedures conform with the regulations
Providing 'Written Procedures' for all medical exposures.
IRMER Referrers
They are responsible for supplying the IRMER Practitioner with sufficient information to
justify an appropriate exposure.
IRMER Practitioners
They are clinically responsible for justify all medical exposure. Justification must be based on
consideration of:
1. The aim of the exposure
2. The total potential benefit to the patient
3. The risk to the patient
4. The efficacy, benefits and risks of alternative techniques.
In private clinic, all general dental practitioners and specialist orthodontists in practice
are IRMER Practitioners and are therefore required by law to justify every radiograph that
they take.
In hospitals, orthodontists are IRMER Referrers as they refer their patients to an X-ray
Department to be imaged. As such they are responsible for supplying sufficient clinical
information so that the IRMER Practitioner within the X-ray Department can justify the
exposures.
IRMER Operators
They are responsible for conducting any practical aspect of a medical exposure including
exposing the radiograph or processing the film. IRMER Operators and IRMER Practitioners
must have received adequate training and education.
Radiation dose delivered by diagnostic imaging and the magnitude of the risks involved
Radiation dose is complicated by the fact that several different measurements of 'dose' exist.
The main terms are:
1. Radiation absorbed dose
2. Equivalent dose
3. Effective dose.
RADIATION ABSORBED DOSE (D)
This is a measurement of the amount of energy absorbed from the X-ray beam per unit mass
of tissue. It is measured in Joules/kg. The Standard International (SI) unit is the Gray (Gy).
EQUIVALENT DOSE (H)
This is a measurement of radiation dose that takes into account the radiobiological
effectiveness and damage caused by different types of radiation.
Each type of radiation is allocated a different radiation weighting factor (WR).
X-rays and gamma rays have a weighting factor of 1, while the more damaging protons
and alpha particles have a weighting factor of 2 and 20 respectively.
The equivalent dose is calculated by multiplying the radiation absorbed dose (the amount
of energy absorbed by the tissue) by the radiation weighting factor (RW) for the type of
radiation being used.
The Standard International unit is the Sievert (Sy).
EFFECTIVE DOSE (E)
This is a measurement which allows doses from different parts of the body to be compared, by
converting all doses into an equivalent whole body dose.
The most radiosensitive organs and tissues in the body are given tissue weighting factors.
When an exposure involves one of these tissues the equivalent dose is multiplied by the
appropriate tissue weighting factor (TW) to give an effective dose.
The Standard International unit is same as above the Sievert (Sy).
Effective doses and risks from exposure to x-rays in orthodontic practice
NB:
The annual global per capita effective dose due to natural background radiation sources
alone is estimated to be about 2400 mSv at sea level, and may be of wide range between 1000
and 3000 mSv. Consequently, the natural background radiation is estimated to be about 8
mSv per day.
In case of i-cat there is 5msv for each 1cm if the voxel size is 0.4mm. keeping in mind
that we need exposure area of 4-5cm for each jaw and for the whole skull we need 22cm
(Chung 2013)
Radiographs that used in IO
1. PA is size is large 31*41 or small 22*35
2. Occlusal size 57*76, for vertex occlusal we need to use intensifying screen to increase
radiographical exposure and the beam should be perpendicular to OP at hairline level
3. For oblique occlusal in the UA the angle is 65-70 while in the lower is -45 degree
4. Lateral oblique size 130*180 and we can use normal dental x-ray machine after removing
the rectangular collimator
5. OPT , size 130*240. Its problems are artefact, ghost image from other side of the mouth
and cervical spine, air shadow may simulate caries, magnification,
6. Cephaolgram, siz 180*240,
Practical and physical methods available for reducing or limiting the dose to patients
1. The equipment
2. Radiological technique
3. Clinical judgement in justification and interpretation.
4. Quality Assurance
1. EQUIPMENT
X-ray units should:
Operate at high kV (60-70kV for intra-oral equipment)
Incorporate adequate aluminium filtration
Incorporate appropriate beam collimation
Be both critically examined and acceptance tested
Incorporate warning signals.
Conventional image receptors should:
Be the fastest available film speed — typically F speed
Involve rare-earth intensifying screens for extra-oral radiography.
Digital image receptors should:
Be used with exposures that have been optimised in consultation with the Radiation
Protection Advisor
2. Radiographic techniques
1. Intra-oral periapicals and bitewings should:
accurate film positioning
film holders
Be taken using rectangular collimation
Be chemically or digitally processed correctly.
2. Intra-oral upper occlusal radiographs should:
Be taken using rectangular collimation
Include the use of a thyroid shield or collar if the thyroid gland lies in the primary beam.
3. Panoramic radiographs should:
Ensure accurate patient positioning assisted by light beam markers
Allow field limitation techniques and appropriate collimation of panoramic images such
as 'dentition only', which results in a 50% dose reduction.
4. Lateral cephalometric radiographs should.
Ensure accurate patient positioning assisted by light beam markers
Include triangular collimation, facilitated by a light beam diaphragm, so as not to
irradiate the whole of the cranium and neck
Include an aluminium wedge filter, ideally at the X-ray tube head, to facilitate the
imaging of the soft tissue
5. Cone beam imaging should:
Ensure accurate patient position assisted by light beam markers
Use the smallest field of view compatible with the clinical situation.
The indication according to Issacsson 2007
I. For diagnosis and TP
a. Other than Cephalometric
For a patient under 9 years
For patient above 9 years
b. Cephalometric
Below 10 years
Age 10-18 years
age above 18 years
II. Monitoring of treatment
Unerupted teeth
Iatrogenic factors
Treatment progress
III. End of active tooth movement
IV. Growth and post-treatment changes
In details
1. For diagnosis and TP
c. Other than ceph
1. For a patient under 9 years
If incisors or molar are overdue and there is a clinical triggers to have a problem
If the incisors are rotated or crowded severely then consider x-ray
If the OJ increases or reversed severely then consider x-ray
Delayed eruption
2. For patient above 9 years
If the incisors are rotated or crowded severely then take x-ray
If the OJ increases or reversed severely then consider x-ray
Submerged teeth then take x-ray
Canine not palpable then take x-ray
Delayed eruption
d. Cephalometric
1. Below 10 years
Only if the condition is sever class II or class III which need early treatment
2. Age 10-18 years
The condition should be:
class II or class III, Bimaxillary
and
Treatment for both arch
and
will start soon
and
functional or U and L FA for both arches or extraction with change in the incisor position
3. age above 18 years
CL2 D1 , Cl2D2 , Cl3 , Bimax and
Treatment for both arch and
will start soon and
surgery or U & L FA
or extraction with change in the incisor position
History of previous orthodontic treatment may need investigation, but localised intra-oral
radiographs may be sufficient
1. Only 4-20 % of treatment plan can be changed after radiograph examination
compared with no radiograph taken (Brukes 1999, Whaite 1992).
2. Devereux & Cunningham 2011 showed that the use of ceph will not change the TP
3. Study model: Han and Vig 1991showed that in class II cases, the study model alone
in a majority of cases (55%), provided adequate information for treatment
planning, and incremental addition of information from other types of diagnostic
records made small differences.
4. Cephalometric: Nijkamp 2008, that cephalometrics are not required for orthodontic
treatment planning, as they did not influence treatment decisions for patient with
class II malocclusion.
2. MONITORING OF TREATMENT
A. Unerupted teeth
1. It is important to ensure that the repeat images are taken in an identical position to the
original to ensure a reliable comparison.
2. Intra-oral views (periapical or occlusal), should be considered
3. A panoramic radiograph (with appropriate field limitation) can be used to monitor the
changes in position of several unerupted teeth
B. latrogenic factors
1. If there is evidence of excessive tooth mobility during treatment.
2. where there is abnormal delay of tooth movement
3. an indication of apical disease,
4. a risk of resorptions E.g Root apices, which are blunt or pipette-shaped.
C. Treatment progress
1. Where orthodontic treatment precedes implant or other restorative procedures, localised
periapical radiographs to show root angulations may be required
2. End of functional appliance and before starting FA to determine incisor position and the
need for extraction, anchorage and treatment mechanics.
3. Few months before appliance removal will allow the orthodontist to carry out any
necessary adjustments to achieve the treatment targets.
3. End of active tooth movement
1. Should be assessed carefully for each patient and is unlikely to be indicated except for
patients with severe malocclusions.
2. It is used as baseline to check future changes.
4. Growth and post-treatment changes
1. It is difficult to define and has to be assessed for each patient.
2. They may be indicated in patients where stability is uncertain either as a result of a
specific type of treatment or because unfavourable growth is anticipated.
There are no orthodontic indications for the following:
1. Radiographs before a clinical examination
2. A set of routine radiographs for all orthodontic patients