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IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
RADIATION PROTECTION IN
DIAGNOSTIC AND
INTERVENTIONAL RADIOLOGY
L 21: Optimization of Protection in Pediatric
Radiology
IAEA
International Atomic Energy Agency
Introduction
• Good radiation protection policy in pediatric
radiology is essential.
• International guidelines are available to
assist in optimization of image quality and
radiation dose in pediatric imaging
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Topics
General recommendations
Quality criteria for radiographic
images (EUR-16261 document)
Recommendations for X Ray
equipment and rooms for
pediatric radiology
References
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Overview
• To become familiar with the principles of
radiation protection in pediatric radiology,
the X Ray systems to be used and the
principles of optimization and quality control
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IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
Part 21: Optimization of Protection in
Pediatric Radiology
Topic 1: General recommendations for pediatric
radiology
IAEA
International Atomic Energy Agency
General recommendations for
pediatric radiology
• General, equipment and installation
considerations
• The generator should provide short exposure times (3
milliseconds) with sufficient power to obtain appropriate
exposure
• The generator should be high frequency to improve the
accuracy and reproducibility of exposures
• Automatic exposure control (AEC) devices should be
used with caution in pediatrics
• AEC should have specific technical requirements for
pediatrics
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General recommendations for
pediatric radiology
• Careful manual selection of exposure factors usually
results in lower doses
• X Ray rooms for pediatrics should be designed for
improving the child’s cooperation (control panel within
easy reach, etc.)
• Fast screen-film combinations or digital radiography
have advantages (reduction of dose) and limitations
• Low-absorbing materials in cassettes, table tops, etc.
are important in pediatrics radiology
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General recommendations for pediatric
radiology
• Many examinations can be carried out without
antiscatter grids (small volume irradiated, less
scatter), thereby reducing the dose to the patient
by a factor of two or more
• Antiscatter grids for pediatrics should have
specific technical requirements
• Antiscatter grid should be removable in pediatric
equipment, particularly fluoroscopic systems
• Image intensifiers should have high conversion
factors for reducing patient dose in fluoroscopic
systems
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General recommendations for pediatric
radiology
• Specific kV-mA dose rate curves for
automatic brightness control (ABC) should
be used in fluoroscopic systems for
pediatrics.
• There should be a “floor” of 70 kV on fluoro
• It is preferable not to use the ABC unless
there is an automatic cut-off device.
• Specific protocols should be used for
pediatric patients in CT, e.g., lower mAs,
lower kVp, etc.
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General recommendations for pediatric
radiology
• Consider the advantages and disadvantages of
under-couch and over-couch fluoroscopy units
• Pulsed fluoroscopy allows for significant patient
dose reduction
• Digital equipment and the use of frame-grab (Last
image hold, or LIH) techniques will result pediatric
dose reduction
• The cine playback (digital) and video playback
(digital or conventional fluoroscopy) in screening
examinations may allow patient dose reductions
• Additional tube filtration will reduce pediatric dose
with no impact on image contrast
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General recommendations for pediatric
radiology
• Reduction of exposure
 Repeat analysis should be carried out as part of
the QC program. Feedback should be provided to
the radiographers
 Immobilization can reduce the repeat rate
 Immobilization devices should be used. The role
of simple aids such as tape, sponge wedges, and
sand bags should also be considered.
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General recommendations for pediatric
radiology
 Short exposure times can improve image quality
and reduce the number of repeat films
 The use of mobile X Ray units for pediatrics
should be restricted due to the difficulty in
obtaining short exposure times
 Radiographers should have specific training in
pediatric radiology
 Gonadal protection is important in pediatric
radiology. Several sizes and types should be
available
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General recommendations for pediatric
radiology
 Collimation is important. Every image
should be collimated to the body part of
interest.
 The correct patient positioning and
collimation is important in pediatrics,
particularly for excluding the gonads from
the direct beam
 It is important to establish whether
adolescent girls might be pregnant when
abdominal examinations are contemplated
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General recommendations for pediatric
radiology
 Motion is a major problem in children and
could require specific adjustment of
radiographic techniques
 Proper consultative relationship between the
referring physician and the radiologist is
especially important in pediatrics
 Protocols and diagnostic pathways should be
promoted
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General recommendations for pediatric
radiology
 Some radiological examinations are of
questionable value in children (e.g., followup chest radiographs in simple pneumonia,
abdominal radiographs in suspected
constipation, etc.)
 The repetition of a radiological examination
in pediatrics should be at the discretion of
the radiologist.
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General recommendations for pediatric
radiology
Appropriate projections for minimizing
dose in high risk tissues should be used (PA
projections should replace AP where possible for
spinal examinations)
Additional filters should be available to
enable them to be easily changed (1 mm Al; 0.1
and 0.2 mm Cu should be available).
Shaped filters are available to reduce dose
and improve image quality for full spine
radiographs
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General recommendations for pediatric
radiology
 Dedicated pediatric room or complete sessions
dedicated to pediatric radiography should be
available
 Experienced staff who can obtain the child’s
confidence and cooperation in a secure and childfriendly environment are of paramount
importance in reducing radiation doses in
pediatrics
 Specific referral criteria for pediatric radiology
should be available, e.g., for head injury where the
incidence of injury is low
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General recommendations for
pediatric radiology
• Referral criteria for all X Ray examinations of children
should be established, especially those which may be
age-related, e.g., scaphoid not ossified below age of 6
years; nasal bones cartilaginous below age of 3 years
• Higher kV techniques should be used when possible in
order to reduce pediatric doses.
• Long focus patient distances could be used to
minimize patient entrance dose (with the compromise of
appropriate exposure times)
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General recommendations for
pediatric radiology
• Fluoroscopy should not be used for patient
positioning.
• Audit and quality control is essential for
optimizing image quality and patient dose
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General recommendations for
pediatric radiology
Risk factors
• Pediatric examinations require special consideration in
the justification process since children are at greater risk
of incurring stochastic effects,
• The benefit of high dose, high risk examinations (e.g.,
computed tomography, IVU, etc.) should be carefully
weighed against the increased risk
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General recommendations for pediatric
radiology
Risk factors
Longer life expectancy in children means a greater
potential for manifestation of possible harmful
effects of radiation
Radiation doses used to examine young children
should generally be much lower than those
employed in adults
Risk factors for cancer induction in children is
between 2 and 3 times higher than for adults
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General recommendations for pediatric
radiology
Patient dosimetry – Diagnostic Reference
Levels (DRLs)
 Measuring patient doses in pediatrics presents
special difficulties (small values)
 Dosimetric techniques used in pediatrics
should be specifically adapted
 Patient doses are related to patient size
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General recommendations for pediatric
radiology
 DRLs in pediatrics should be related to patient
size, not age
 DRLs presently available for pediatrics are
limited (See EUR-16261 and NCRP Report on
DRLs, available 2012)
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General recommendations for
pediatric radiology
Protection of personnel and parents
• Parents can cooperate in the radiological
examination of their children if they are
duly informed and protected
• Parents’ exposure in this situation can be
considered as a medical exposure but
optimization criteria must be applied
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General recommendations for
pediatric radiology
• Parents or helpers should be duly
informed and should know exactly what is
required of them
• Pregnant women should not be allowed to
help during pediatric examinations
• Lead aprons and lead gloves (if the hands
are near the direct radiation field) should
be used
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ICRP-ISR “smart” message for
pediatrics
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IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
Part 21: Optimization of protection in
Pediatric Radiology
Topic 2: Quality criteria for radiographic images
(EUR document)
IAEA
International Atomic Energy Agency
European Guidelines on
Quality Criteria for
Diagnostic Radiographic
Images in Paediatrics,
July 1996.
EUR 16261 EN
Free PDF version
available at:
http://www.cordis.lu/fp5euratom/src/lib_docs.htm
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Criteria related to images
• The Image Criteria for pediatric patients presented
for a particular type of radiograph are those
deemed necessary to produce an image of
standard quality
• No attempt has been made to define acceptability
for particular clinical indications
• The image criteria allow an immediate evaluation
of the image quality of the respective radiograph.
They are appropriate for the most frequent
requirements of radiographic imaging of pediatric
patients
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Criteria related to images
• The anatomical features and body proportions vary
due to the developmental process in infancy,
childhood and adolescence
• They are different in the respective age groups and
are distinct from those of a mature patient
• The Guidelines presuppose knowledge of the
changing radiographic anatomy of the developing
child.
• The term “consistent with age” indicates that the
respective image criteria essentially depend on the
age of the patient
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Criteria related to images
• The smaller body size
• The age dependent body composition
• The lack of co-operation and many
functional differences (e.g., higher heart
rate, faster respiration, inability to stop
breathing on command, increased intestinal
gas, etc.)
• Prevent the production of radiographic
images in pediatric patients to which
standard adult image criteria can be applied
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Criteria related to images
• Correct positioning of pediatric patients will be
more difficult than in co-operative adult patients
• Use of auxiliary devices is essential for effective
immobilization
• Sufficient skill and experience of the imaging staff,
and ample time for the particular examination, are
necessary to obtain quality images in infants and
younger children
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Criteria related to images
• Incorrect positioning is the most frequent
cause of inadequate image quality in
pediatric radiographs
• Image criteria for the assessment of
adequate positioning (symmetry and
absence of tilting etc) are much more
important in pediatric imaging than in adults
• A lower level of image quality than in
adults may be acceptable for certain clinical
indications
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Criteria related to images
• A lower quality image cannot be justified
unless this has been part of optimization
and is associated with a lower radiation
dose
• The fact that the X Ray was taken from of
non-cooperative pediatric patient
(anxious, crying, heavily resisting) is not
an excuse for producing an inferior quality
image which is often associated with
excessive dose
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Criteria for Radiation Dose to the
Patient
• DRLs are expressed as the entrance surface
dose for a “standard sized” pediatric patient
• DRLs are only available for the most
frequently performed types of examinations
for which sufficient data is available
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Criteria for Radiation Dose to the
Patient
• Some form of dose measurement is required in
order to audit patient doses
• This requires representative sampling of the
patient population
• A number of dose measurement methods are
described in the European Guidelines
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General principles associated with
good imaging performance
Image Annotation
• The patient identification, date of examination, position
markers, and name of the facility must be present and
legible on the image
• These annotations should not obscure the diagnostically
relevant regions of the image
• Identification of the individual carrying out the
examination should be on the film
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General principles associated with
good imaging performance
Quality Control of X Ray Imaging Equipment
• Quality control programs should be in use in
every medical X Ray facility and should monitor
image quality and patient dose
• Operating levels and control limits should be
established by a medical physicist
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General principles associated with
good imaging performance
Low Attenuation Materials
• Recent developments in materials for cassettes, grids,
tabletops and front plates of film-changers using carbon
fiber and some new plastics enable significant reduction
in patient doses
• This reduction is most significant in the radiographic
voltage range recommended in pediatric patients and
may reach 40%. Use of these materials should be
encouraged
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General principles associated with
good imaging performance
Patient Positioning and Immobilization
• Patient positioning must be exact whether or not the
patient co-operates.
• For infants, toddlers, and younger children
immobilization devices, will help to assure that:




the patient does not move
the beam can be centered correctly
the film is obtained in the proper projection
accurate collimation limits the field size exclusively to the
required area
 shielding of the remainder of the body is possible.
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General principles associated with good
imaging performance
Patient Positioning
and
Immobilization
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General principles associated with good
imaging performance
Patient
Positioning
and
Immobilization
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General principles associated with good
imaging performance
Patient
Positioning
and
Immobilization
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General principles associated with good
imaging performance
Patient
Positioning
and
Immobilization
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General principles associated with
good imaging performance
Patient Positioning and Immobilization
• Immobilization devices must be easy to use, and
their application atraumatic to the patient.
• Their usefulness should be explained to the
accompanying parent(s).
• Radiological staff members should only hold a
patient under exceptional circumstances
• Examination time allocation must include the
time to explain the procedure not only to the
parents but also to the child
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General principles associated with
good imaging performance
Field Size and X Ray Beam Limitation
• Inappropriate field size is the most important
fault in pediatric imaging
• A field which is too small will exclude
potentially important information
• A field which is too large will not only reduce
image contrast by increasing the amount of
scattered radiation but also result in
unnecessary radiation exposure outside the
area of interest
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General principles associated with
good imaging performance
Field Size and X Ray Beam Limitation
• Correct beam limitation requires proper knowledge of
the external anatomical landmarks by the radiographer
• These differ with the age of the patient according to the
varying proportions of the developing body.
• In addition, the size of the field of interest depends much
more on the nature of the underlying disease in infants
and younger children than in adults
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General principles associated with
good imaging performance
Field Size and X Ray Beam Limitation
• A basic knowledge of pediatric pathology is
required for radiographers to assure proper
beam limitation
• The acceptable minimal field size is set by the
recognizable anatomical landmarks for specific
examinations
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General principles associated with
good imaging performance
Field Size and X Ray Beam Limitation
• Beyond the neonatal period, the tolerance for
maximal field size should be less than 2 cm
greater than the minimal
• In the neonatal period, the tolerance level
should be reduced to 1.0 cm at each edge
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General principles associated with
good imaging performance
Field Size and X Ray Beam Limitation
• In pediatric patients, evidence of the field limits
should be apparent by clear areas of the
exposed image
• Beam-limiting devices which automatically
adjusting to the cassette size are inappropriate
for pediatric patients
• Discrepancies between the radiation beam and
the light beam alignment must be avoided by
regular assessment
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General principles associated with
good imaging performance
Additional filtration
• The soft part of the radiation spectrum which is absorbed in
•
•
•
•
the patient is useless for the production of the radiographic
image and contributes unnecessarily to the patient dose
Part of it is eliminated by the filtration of the tube, tube
housing, collimator etc., but this is insufficient
Most tubes have a minimum filtration of 2.5 mm Al
Additional filtration can further reduce unproductive
radiation and thus patient dose
1 to 2 mm, or more, of aluminum can be added without
reducing contrast
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General principles associated with
good imaging performance
Additional filtration
• For pediatric patients, total radiation dose must be
kept low, particularly when high speed screen-film
systems or image intensified techniques are used
• Not all generators allow the short exposure times
that are required for higher kV technique
• Low radiographic voltage is frequently used for
pediatric patients. This results in comparatively
higher patient doses.
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General principles associated with
good imaging performance
Additional filtration
• Adequate additional filtration allows the use of
higher radiographic voltage with the shortest
available exposure times, overcoming the limited
short exposure time capability
• This makes the use of high speed screen-film
systems and digital radiography possible
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General principles associated with
good imaging performance
Protective Shielding
• For all examinations of pediatric patients, the
examples for “Good Radiographic Technique”
include standard equipment of lead-rubber
shielding of the body in the immediate proximity
of the diagnostic field
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General principles associated with
good imaging performance
Protective Shielding
• For exposures of 70 - 80 kV, maximum
gonadal dose reduction of about 30 to 40%
can be obtained by shielding with 0.25 mm
lead equivalent rubber immediately at the
field edge
• However, this is only true when the
protection is placed correctly at the field
edge
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General principles associated with
good imaging performance
Protective Shielding
• The gonads in "hot examinations", i.e., when
they lie within or close (nearer than 5 cm) to the
primary beam, should be protected whenever
possible without impairing necessary diagnostic
information
• Various sized gonad shield should be available
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General principles associated with
good imaging performance
Protective Shielding
• By properly adjusting male gonad shields the absorbed
dose in the testes can be reduced by up to 95%
• In girls, shadow masks within the diaphragm of the
collimator are as efficient as direct shields. They can be
positioned more easily and do not slip as easily as with
contact shields
• When shielding of the female gonads is effective, the
reduction of the absorbed dose in the ovaries will be
about 50%
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General principles associated with
good imaging performance
Protective Shielding
• There is no reason to include the male gonads
within the primary radiation field for radiographs
of the abdomen
• The same applies, usually, for films of the pelvis
and micturating cystourethrography. The testis
should be protected with male gonad shields,
and kept outside the field
• Gonad protection is not possible for females for
abdominal examinations
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General principles associated with
good imaging performance
Protective Shielding
• In practice, the great majority of pelvic films
show that female gonad protection is completely
ineffective
• There are justifiable reasons for omitting gonad
protection for pelvic films in girls, e.g., trauma,
incontinence, abdominal pain, etc.
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General principles associated with
good imaging performance
Protective Shielding
• The eyes should be shielded for X Ray
examinations involving high absorbed doses to
the eyes, e.g., for conventional tomography of
the petrous bone, when patient cooperation
permits
• The absorbed dose to the eyes can be reduced
by 50% - 70%
• In imaging of the skull the use of PA-projection
rather than the AP-projection can reduce the
absorbed dose in the eyes by 95%
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General principles associated with
good imaging performance
Protective Shielding
• PA-projection, therefore, should be preferred as
soon as patient age and co-operation permit prone
or erect positioning
• Developing breast tissue is particularly sensitive to
radiation, consequently exposure must be limited
• The 16 year old’s breast tissue is 16 times more
sensitive to cancer induction that the 40 year old’s
breast tissue.
• The most effective method is by using the PAprojection, rather than the AP
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General principles associated with
good imaging performance
Protective Shielding
• While this is well accepted for chest
examinations, the greatest risk is during
spinal examinations, and here PA
examinations must replace AP
• It should also be remembered that thyroid
tissue should be protected, whenever
possible, e.g., during dental and facial
examinations, and are protected in PA
projections
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General principles associated with
good imaging performance
Radiographic Exposure Conditions
• Knowledge and correct use of appropriate
radiographic technique factors, e.g.,
radiographic voltage, nominal focal spot size,
filtration, source-to-image distance, due to their
impact on patient dose and image quality
• Permanent characteristics of the equipment
such as total tube filtration and grid
specifications should also be taken into
consideration
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General principles associated with
good imaging performance
Automatic Exposure Control
• Adult patients vary in size, but their variation is
minimal compared to the range in pediatric
patients from premature infants, weighing
considerably less than a thousand grams, to
adolescents approaching 70 kg, or more
• AEC is helpful in obtaining appropriately
exposed radiographs in pediatric imaging
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General principles associated with
good imaging performance
Automatic Exposure Control
• Many of the AEC systems commonly available are
not satisfactory
• They have relatively large and fixed ionization
chambers. Neither their size, shape, nor position is
appropriate for the many variations of body size and
proportion in pediatric patients
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General principles associated with
good imaging performance
Automatic Exposure Control
• AEC use may be associated with the use
of the grid (where the grid is not
removable) which is frequently
unnecessary
• Optimal AEC systems must provide a
method to compensate for different speed
image receptors.
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General principles associated with
good imaging performance
Automatic Exposure Control
• Image receptors and AEC chambers are
energy dependent, particularly at lower
radiographic voltage. Adequate
compensation must be provided
• AECs increase the minimal exposure times
• All these factors must be considered when
AECs are used in pediatric patients
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General principles associated with
good imaging performance
Automatic Exposure Control
• Specially designed pediatric AECs have a
small, mobile detector for use behind a
cassette (without lead backing)
• The AEC position can be selected with
respect to the most important region of
interest
• Positioning is critical and difficult
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General principles associated with
good imaging performance
Automatic brightness control
• Automatic brightness control (ABC) must
be switched off during fluoroscopic
examinations where there are relatively
large areas of contrast material, to avoid
excessive dose rates, e.g., full bladders
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Guidance on implementation of
quality criteria
• Quality Criteria are presented in the European
Guidelines for a number of selected radiographic
projections used in the course of routine types of X
Ray examination
• They apply to pediatric patients with the usual
presenting symptoms for the type of examination
being considered
• They are to be used by radiologists, radiographers,
and medical physicists as a check on the routine
performance of the entire imaging process
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Guidance on implementation of
quality criteria
• The Quality Criteria cannot be applied to all
cases
• A lower level of image quality may be
acceptable for certain clinical indications—
Ideally this should be associated with
lower patient dose.
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Guidance on implementation of
quality criteria
Under no circumstances
should an image which fulfils
all clinical requirements
but does not meet all image
criteria ever be repeated
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Diagnostic Reference Levels in
Pediatrics
Examples of Diagnostic Reference Levels in Pediatrics, for standard fiveyear-old patients, expressed in entrance surface dose per image, for single
views (from EUR-16261)
Radiograph
5-year old patient.
Reference Dose
Entrance Surface Dose
per SINGLE VIEW. [µGy] *)
Chest Posterior Anterior (PA)
100
Chest Anterior Posterior (AP, for non-cooperative patients)
100
Chest Lateral (LAT)
200
Chest Anterior Posterior (AP NEWBORN)
Skull Posterior Anterior/ Anterior
Posterior (PA/AP)
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80
1500
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Diagnostic Reference Levels in
Pediatrics
Examples of Diagnostic Reference Levels in Pediatrics, for standard
five-year-old patients, expressed in entrance surface dose per image,
for single views (from EUR-16261)
Radiograph
Skull Lateral (LAT)
5-year old patient. Reference
Dose
Entrance Surface Dose
per SINGLE VIEW. [µGy] *
1000
Pelvis Anterior Posterior (AP)
900
Pelvis Anterior Posterior (AP - INFANTS)
200
Abdomen (AP/PA with vertical/horizontal
beam)
1000
Criteria for radiation dose to the patient: The entrance surface dose for
standard-sized patients is expressed as the absorbed dose in air (µGy) at
the point of intersection of the beam axis with the surface of a paediatric
patient, backscatter radiation included.
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IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
Part 14.1: Optimization of Protection in
Pediatric Radiography
Topic 3: Recommendations for X Ray room and
equipment
IAEA
International Atomic Energy Agency
Recommendations for X Ray room and
equipment for pediatrics
• Visibility of the patient and easy audio
communication from the control panel
• High frequency generators of 600-800 mA with
linearity from 50 to120 kV
• Exposures of 3 ms should be possible. AEC
devices should be specifically adapted
• Different control for the anode rotation and
exposure (specially important for chest
examinations to avoid respiratory movement)
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Recommendations for X Ray room and
equipment for pediatrics
• Low absorption materials and plastic
cassette fronts should be used
• Antiscatter grid should be removable
• Grid motion should be rapid to avoid grid
artifacts at short exposure times.
• A 15-cm Image intensifier (I.I.) or flat panel
fluoroscopic system is an appropriate size
for pediatrics. Larger sizes or multi-mode
systems are not needed.
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Recommendations for X Ray room and
equipment to be used in pediatrics
• The use of additional x-ray beam filtration
significantly reduces patient dose
• Mobile X Ray system for pediatrics should
have the high output in order to allow for
short exposure times
• Immobilization devices should be available
in pediatric rooms
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Summary
• Particular attention should be paid to technical
specifications of X Ray equipment and protocols
used in pediatric imaging.
• Radiologists and radiographers should be
specifically trained for pediatric imaging.
• Increased sensitivity for carcinogenesis of pediatric
patients should be taken into account when any
decisions are made about equipment and
protocols
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References
• European guidelines on quality criteria for diagnostic radiographic
images in pediatrics, EUR 16261 report, (Luxembourg, EC), 1996.
http://www.eradiography.net/regsetc/European_guide_children_extract.pdf
• ICRP Publication 34, Protection of the Patient in Diagnostic Radiology.
Annals of the ICRP (2/3) 1982.
• NCRP 68. Radiation protection in pediatric radiology, 1981.
• Guidelines on education and training in radiation protection for medical
exposures. Radiation Protection 116. European Commission 2000.
Available at: http://europa.eu.int/comm/environment/radprot
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References
• Guidance on diagnostic reference levels (DRLs) for medical
exposures. Radiation Protection 109. European
Commission 1999. Available at:
http://europa.eu.int/comm/environment/radprot
• Rational use of diagnostic imaging in pediatrics. WHO,
1987.
• Diagnostic reference levels for adult and pediatric patients,
National Council on Radiation Protection and Measurement
(NCRP), Bethesda, MD. In press (available 2012)
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