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Radiation Protection in Paediatric Radiology. Radiation Protection of Children in Screen Film Radiography. L03. Educational objectives. At the end of the programme, the participants should: Become familiar with specific radiation protection issues in paediatric radiography

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radiation protection in paediatric radiology

Radiation Protection in Paediatric Radiology

Radiation Protection of Children in Screen Film Radiography

L03

educational objectives
Educational objectives

At the end of the programme, the participants

should:

  • Become familiar with specific radiation protection issues in paediatric radiography
  • Identify the features of radiographic imaging equipment used in paediatric radiology
  • List important operational considerations in paediatric radiography
  • Discuss important considerations in paediatric radiography using mobile X-ray units

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

answer true or false
Answer True or False
  • Added filtration will reduce the dose to the patient.
  • Short exposure time is a disadvantage.
  • Proper collimation reduce dose.
  • Shielding of radiosensitive organs is recommended in paediatric radiography.

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

contents
Contents
  • Justification in radiography
  • Practical optimisation in paediatric radiography
    • Equipment related
    • Radiographic technique related
  • Important consideration for mobile radiography
  • Image quality and patient dose

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

introduction
Introduction

Children have higher radiation sensitivity than adults due to a longer life expectancy

For children under age of 10, the probability for fatal cancer is 2-3 times higher than for whole population

The higher radio-sensitivity of the patients should be taken into account

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

5

introduction1
Introduction

Radiologists and radiographers should be specifically trained for paediatrics

A paediatric radiological procedure should be individually planned and projections should be limited to what is absolutely necessary for a diagnosis

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

6

general recommendations
General recommendations

Key areas in radiation protection in paediatric

radiology:

  • Justification
  • Optimisation
  • Evaluation of patient dose and image quality

“Do you really need a glossy picture to

make that diagnosis”

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

justification in radiography
Justification in radiography
  • Justification is required for all radiographic studies
  • Ask referring practitioner, patient, and/or family about previous procedures
  • Use referral guidelines where appropriate and available
  • Use alternative approaches, such as ultrasound, MRI where appropriate
  • Consent, implied or explicit,is required for justification
  • Include justification in clinical audit

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

justification in radiography1
Justification in radiography
  • Referral guidelines for radiological examinations:
    • EUROPEAN COMMISSION, Referral Guidelines for Imaging, Luxembourg, Radiation Protection 118, Office for Official Publications of the European Communities, Luxembourg (2001) and Update (2008)
    • THE ROYAL COLLEGE OF RADIOLOGISTS, Making the Best use of Clinical Radiology Services (MBUR), 6th edition, RCR, London (2007)

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

examples of radiography examinations not routinely indicated
Examples of radiography examinations not routinely indicated
  • Skull radiograph in a child with epilepsy
  • Skull radiograph in a child with headaches
  • Sinus radiograph in a child, under 5 years, suspected of having sinusitis
  • Cervical spine radiograph in a child with torticollis without trauma
  • Radiographs of the opposite side for comparison in limb injury

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

optimisation in radiography
Optimisation in radiography
  • Justified studies must be optimised
  • Various actions taken contribute to systematic dose savings (from a factor of two to ten, with the result that their combined effect can dramatically reduce dose)
  • Sustain good practice through a quality assurance and constancy checking program

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

optimisation in radiography1
Optimisation in radiography

Selection of equipment:

  • Influence on patient dose and image quality
  • But, good radiographic technique is the main factor in improving quality without increasing dose

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

practical optimisation measures in radiography i
Practical optimisation measures in radiography (I)
  • Have a standard type and number of projections for specific indications
  • Views in addition to standard should only be performed on a case-by-case basis
  • Use manual technique selection pending equipment developments on small patients or body parts
  • Where practical use a long (or the recommended) Focus-to-Film Distance

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

practical optimisation measures in radiography ii
Practical optimisation measures in radiography (II)
  • Carefully collimate the X-ray beam to area of interest, excluding other regions, especially gonads, breast, thyroid and eyes
  • Use appropriate gonad, thyroid, and breast shielding
  • Fast film-screen combinations are acceptable for the majority of indications
  • Antiscatter grid is often unnecessary in children – do not use grid for abdominal examination in patients under age of 3, for skull radiography for patients under age of 1 and any fluoroscopy examination unless high detail is required (Cook, V. Imaging, (13) 2001:229–238)

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

practical optimisation measures in radiography iii
Practical optimisation measures in radiography (III)
  • Use PA projections, where practical, for chest and spine radiographs
  • Make sure the correct filtration is used to reduce entry dose
  • Use as high a kVp as is consistent with examination requirements
  • Consider additional filtration at higher kVp
  • Balance the use of a small focal spot size and short exposure times

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

practical optimisation measures in radiography iv
Practical optimisation measures in radiography (IV)
  • Use of quality assessment, quality assurance and audit programs for all aspects of the department’s work, including film processing and justification
  • Introduce and use a system that allows patient dose be assessed regularly
  • Monitor reject rate and the causes (overexposure, underexposure, positioning, motion, and collimation problems)

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality
1. Generators

For paediatric examinations, the generator should be:

a high frequency

multi-pulse (converter)

of sufficient power

nearly rectangular waveform with minimal voltage ripple

Equipment, practice, dose and image quality

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality1
2. Exposure time

When children are uncooperative they may need immobilization

They have faster heart and respiratory rates

Short exposure times improve quality without increasing dose

Only possible with powerful generators and accurate exposure time switches

Equipment, practice, dose and image quality

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality2
3. Focal Spot

Small focal spot

Improves image quality

May in some machines increase exposure time and motion artefacts

Choice depends on exposure parameters: time, kVp and FFD (Focus-to-Film Distance)

Recommendation: focal spot should be 0.6 -1.3mm

Equipment, practice, dose and image quality

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality3
4. Additional filtration

Additional filtration may lead to dose reduction

0.1 mm of Cu in addition to 2.5 mm of Al*

reduce ESAK by 20%

barely noticeable reduction in image quality

Some modern systems canautomatically insert either 0.1mm or 0.2 mm Cu depending on the examination

Equipment, practice, dose and image quality

*Cook, V., Imaging, (13) 2001:229–238

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

dose reduction with added filtration
Dose reduction with added filtration

From: Mooney and Thomas : Dose reduction in a paediatric X-ray department following optimization of radiographic technique, BJR (77) 1998:852-860

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality4
5. Exposure factors

Increased kVp (reduced mAs):

Greater penetration and less absorption

Reduced patient dose for a constant film density

Neonatal chest:

Minimum 60kVp: less contrast but better assessment of lung parenchyma

Lower kVp if looking for bone detail

Equipment, practice, dose and image quality

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality5
6. Antiscatter grid

Often unnecessary in children because smaller irradiated volume (and mass) results in less scattered radiation.

Limited improvement in image quality but increased dose of ~50% with the use of antiscatter grids

Equipment, practice, dose and image quality

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

antiscatter grids
Antiscatter grid should be removable in paediatric equipment

Remove antiscatter grid for:

abdominal imaging in young children especially <3 years old

skull imaging <1 year old

in most fluoroscopic imaging

Antiscatter grids

Cook, V., Imaging, (13) 2001:229–238

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

antiscatter grids1
If used for children,

Antiscatter grids should have*:

Grid ratio (r) > 8:1

Line numbers: >100 cm-1

Low attenuation intersperse material, such as carbon fibre

Alternative: air gap technique

(reduces the effect of scatter

without dose increase, but the

image is magnified)

Antiscatter grids

*Cook, V., Imaging, (13) 2001:229–238

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality6
Equipment, practice, dose and image quality

7. Automatic Exposure Control (AEC)

  • Generally not appropriate for small children
  • Sensors (size and geometry) are normally designed for adult patients
  • AEC use may be associated with the use of the grid (where the grid is not removable), which is frequently unnecessary
  • AEC should have specific technical requirements for paediatrics
  • If not appropriate oravailable, carefully applied exposure charts are preferred

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

automatic exposure control
Automatic Exposure Control
  • Specially designed paediatric AEC:
    • Small mobile detector for use behind a lead-free cassette
    • Position can be selected with respect to the most important region of interest
    • This must be done extremely carefully, as even minor patient movement may be disastrous

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality7
Equipment, practice, dose and image quality

8. Focus-to-film distance (FFD)

  • Longer focus-to-film distances
  • Smaller skin dose
  • Combined with a small object-to-film distance, results in less magnification (less geometric distortion) and improved quality

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality8
Equipment, practice, dose and image quality

9. Image receptors

  • Fast screen-film combinations have advantages (reduction of dose) and limitations (reduced resolution)
  • Low-absorbing materials in cassettes, tables, etc., are specially important in paediatric radiology (carbon fibre)

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

film screen systems
Film-screen systems
  • Fast screen-film system:
    • shorter exposure times (requires a good generator)
    • reduction in radiation dose and prevention of artefacts
  • Recommendations:
    • 200 speed: bone
    • 400 speed: general
    • >700 speed – constipation transit abdominal radiographs, follow-up films, e.g. scoliosis and hips, swallowed foreign body,…

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality9
Equipment, practice, dose and image quality

10. Collimation

  • The most important factor for improving image quality whilst also reducing dose
  • The most common radiographic fault
  • Good collimation/coning is essential to achieve better contrast and avoid exposing unnecessarily other body parts (dose reduction)
  • Body parts outside the region of interest should not be in the X-ray field

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

collimation
Collimation
  • Require a basic knowledge of paediatric pathology
      • Lung fields extremely large in congestive heart failure & emphysematous pulmonary diseases
      • Diaphragm, high in intestinal meteorism, chronic obstruction or digestive diseases
  • Beam-limiting devices automatically adjusting the field size to the full size of the cassette are inappropriate for children
  • Minimal deviation from the radiation and light beam may have large effects in relation to the usually small field of interest - check light beam diaphragm regularly

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

collimation1
Collimation
  • Alignment agreement among the collimators, radiation beam and the light beam must be regularly assessed
  • 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
  • In paediatric patients, evidence of the field limits should be apparent by clear rims of unexposed film

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

slide34

Cook, J.V., Imaging, 13 (2001), 229–238

Neonatal anteroposterior supine chest and

abdomen radiograph of newborn: all four cone

marks visible, with no extraneous body parts

included and lead masking of the gonads.

Lateral skull radiograph (horizontal beam and

round cone)

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

equipment practice dose and image quality10
Equipment, practice, dose and image quality

11. Shielding

  • Standard equipment of lead-rubber shielding of the body in the immediate proximity of the diagnostic field
  • Special shielding has to be added for certain examinations to protect against external scattered and extra-focal radiation

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

shielding
Shielding

For exposures of 60 - 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

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

36

shielding1
Shielding

The gonads in "hot examinations", when they lie within or close to (nearer than 5 cm) the primary beam, should be protected whenever this is possible without impairing necessary diagnostic information

It is best to make one's own lead contact shields for girls and lead capsules for boys

Must be available in varied sizes

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

37

shielding2
Shielding

With appropriate shielding 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.

When shielding of the female gonads is effective, the reduction of the absorbed dose in the ovaries can be about 50%

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

38

shielding3
Shielding

The eyes should be shielded for X-ray examinations involving high absorbed doses in the eyes, e.g., for conventional tomography of the petrous bone, when patient cooperation permits

The absorbed dose in the eyes can be reduced by 50% - 70%

In any radiography of the skull the use of PA-projection rather than the AP-projection can reduce the absorbed dose in the eyes by 95%

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

39

equipment practice dose and image quality11
Equipment, practice, dose and image quality

12. Patient Positioning and Immobilization

  • Patient positioning must be exact, whether or not the patient co-operates.
  • In infants, toddlers and younger children immobilization devices, properly applied, must ensure that:
    • the patient does not move
    • the beam can be centred 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.

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

patient positioning and immobilization
Patient Positioning and Immobilization

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

patient positioning and immobilization1
Immobilization devices must be easy to use

Their usefulness should be explained to the accompanying parent(s)

Radiological staff members should only hold a patient under exceptional circumstances

Even in quite young children the time allocation for an examination must include the time to explain the procedure not only to the parents but also to the child

Patient Positioning and Immobilization

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

mobile radiography
Mobile radiography
  • Mobile radiography is valuable on occasions when it is impossible for the patient to come to the radiology department
  • It can result in
    • poorer quality images
    • unnecessary staff and patient exposures
  • Where practicable, X-ray examinations should be carried out with fixed units in an imaging department
  • Mobile units should only be used with those who cannot safely be moved to such a unit

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

mobile radiography1
Mobile radiography
  • High output converter generators are recommended
  • Capacitor discharge systems should be avoided (they have significant pre- and post-peak soft radiation)
  • Appropriate collimation is

essential to avoid exposing

organs outside the diagnostic

area of interest

  • Other principles outlined above, should be followed with mobile radiography

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

mobile radiography2
Mobile radiography
  • Scattered radiation must be managed to reduce dose to the patient, parents/guardians and to hospital personnel
  • The advice of the medical physicist/radiation protection officer should be obtained on how best to do this.

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

mobile radiography3
Mobile radiography

Recommendations for Intensive Care Unit

(Duetting et. al. Pediat. Radiol. 29: 158-62 (1999)):

  • No additional protection for neighbouring premature infants is necessary
  • The radiographer should wear a lead apron
  • Parents and personnel need not interrupt their activities or leave the room during an X-ray examination
  • When using a horizontal beam, the beam, must be directed away from other persons – use lead shield

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

criteria related to images
Criteria related to images
  • Incorrect positioning is the most frequent cause of inadequate image quality in paediatric radiographs
  • Image criteria for the assessment of adequate positioning (symmetry and absence of tilting etc) are much more important in paediatric imaging than in adults
  • A lower level of image quality than in adults may be acceptable for certain clinical indications

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

criteria related to images1
Criteria related to images

Guideline resources:

  • European Guidelines on Quality Criteria for Diagnostic Radiographic Images in Paediatrics
  • American College of Radiology

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

quality criteria list
Quality Criteria List

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

chest pa ap projection
Chest-PA/AP projection

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

50

chest radiography pa ap projection
Chest radiography-PA/AP projection

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

typical dose levels in paediatric radiography
Typical dose levels in paediatric radiography

NATIONAL RADIOLOGICAL PROTECTION BOARD, Doses to Patient from Medical X Ray Examinations in the UK: 2000 review, NRPB-W14, Chilton (2002).

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

icrp isr smart message for paediatrics
ICRP-ISR “smart” message for paediatrics

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

slide54

http://rpop.iaea.org/RPoP/RPoP/Content/index.htm

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

summary
Summary

Particular attention should be given to technical specifications of X-ray equipment

Good radiographic technique is the main factor in improving quality without increasing dose for protocols used in X-ray paediatric radiology

Justification of practice

Application of practical optimisation measures in radiography

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

55

answer true or false1
Answer True or False
  • Added filtration will reduce the dose to the patient.
  • Short exposure time is a disadvantage.
  • Proper collimation reduce dose.
  • Shielding of radiosensitive organs is recommended in paediatric radiography.

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

answer true or false2
Answer True or False

True - Filtration absorbs low energy photons that are absorbed in patient’s skin and superficial organs and thus giving contributing to dose but not to image formation.

False - It prevents motion artefacts and unnecessary repetitions.

True - Collimation reduces exposed volume, and reduces scatter radiation that affects both image quality and dose.

True - It is especially important for radiosensitive organs as breast, gonads and eyes.

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography

57

references
References
  • European Guidelines on Quality Criteria for Diagnostic Radiographic Images in Paediatrics, July 1996. EUR 16261. Available at: http://www.cordis.lu/fp5-euratom/src/lib_docs.htm
  • Huda W, Assessment of the problem: paediatric doses in screen-film and digital radiography, Pediatr Radiol 34(Suppl 3) 2004:S173-S182
  • Duetting,Foerste,Knoch,Darge and Troeger, Radiation exposure during chest X-ray examinations in a premature intensive care unit: phantom studies, Pediatr Radiol (29) 1999:158-162
  • Mooney and Thomas : Dose reduction in a paediatric X-ray department following optimization of radiographic technique, BJR (77) 1998:852-860
  • Cook, V., Radiation protection and quality assurance in paediatric radiology, Imaging, (13) 2001:229–238.

Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography