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IAEA International Atomic Energy Agency Radiation Protection in Paediatric Radiology Radiation Protection of Children in Screen Film Radiography L03.

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Presentation on theme: "IAEA International Atomic Energy Agency Radiation Protection in Paediatric Radiology Radiation Protection of Children in Screen Film Radiography L03."— Presentation transcript:

1 IAEA International Atomic Energy Agency Radiation Protection in Paediatric Radiology Radiation Protection of Children in Screen Film Radiography L03

2 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 2 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

3 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 3 Answer True or False 1. Added filtration will reduce the dose to the patient. 2. Short exposure time is a disadvantage. 3. Proper collimation reduce dose. 4. Shielding of radiosensitive organs is recommended in paediatric radiography.

4 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 4 Contents Justification in radiography Practical optimisation in paediatric radiography Equipment related Radiographic technique related Important consideration for mobile radiography Image quality and patient dose

5 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 5 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

6 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 6 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

7 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 7 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”

8 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 8 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

9 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 9 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)

10 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 10 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

11 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 11 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

12 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 12 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

13 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 13 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

14 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 14 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)

15 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 15 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

16 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 16 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)

17 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 17 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

18 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 18 Equipment, practice, dose and image quality 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

19 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 19 Equipment, practice, dose and image quality 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 mm

20 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 20 Equipment, practice, dose and image quality 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 can automatically insert either 0.1mm or 0.2 mm Cu depending on the examination *Cook, V., Imaging, (13) 2001:229–238

21 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 21 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: Added filtration0 mm Al3 mm Al ExaminationMean ESD (  Gy)Reduction Abdomen AP 10 months (62 kVp) % Chest AP 10 months (55 kVp) 6440 % Pelvis AP 4 months (50 kVp) 9451 %

22 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 22 Equipment, practice, dose and image quality 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

23 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 23 Equipment, practice, dose and image quality 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

24 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 24 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 Cook, V., Imaging, (13) 2001:229–238

25 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 25 Antiscatter grids 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) *Cook, V., Imaging, (13) 2001:229–238

26 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 26 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 or available, carefully applied exposure charts are preferred

27 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 27 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

28 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 28 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

29 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 29 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)

30 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 30 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,…

31 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 31 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

32 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 32 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

33 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 33 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

34 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 34 Lateral skull radiograph (horizontal beam and round cone) 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. Cook, J.V., Imaging, 13 (2001), 229–238

35 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 35 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

36 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 3636 Shielding For exposures of 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

37 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 3737 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

38 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 3838 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%

39 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 3939 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%

40 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 40 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.

41 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 41 Patient Positioning and Immobilization

42 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 42 Patient Positioning and Immobilization 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

43 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 43 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

44 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 44 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

45 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 45 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.

46 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 46 Mobile radiography Recommendations for Intensive Care Unit (Duetting et. al. Pediat. Radiol. 29: (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

47 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 47 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

48 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 48 Criteria related to images Guideline resources: European Guidelines on Quality Criteria for Diagnostic Radiographic Images in Paediatrics American College of Radiology

49 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 49 Quality Criteria List

50 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 50 Chest-PA/AP projection

51 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 51 Chest radiography-PA/AP projection

52 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 52 Typical dose levels in paediatric radiography Examination ESAK (µGy) Age Abdomen AP Chest PA/AP Pelvis AP Skull AP/ // Skull LAT/340580// NATIONAL RADIOLOGICAL PROTECTION BOARD, Doses to Patient from Medical X Ray Examinations in the UK: 2000 review, NRPB-W14, Chilton (2002).

53 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 53 ICRP-ISR “smart” message for paediatrics

54 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 54

55 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 5555 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

56 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 56 Answer True or False 1. Added filtration will reduce the dose to the patient. 2. Short exposure time is a disadvantage. 3. Proper collimation reduce dose. 4. Shielding of radiosensitive organs is recommended in paediatric radiography.

57 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 57 Answer True or False 1. 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. 2. False - It prevents motion artefacts and unnecessary repetitions. 3. True - Collimation reduces exposed volume, and reduces scatter radiation that affects both image quality and dose. 4. True - It is especially important for radiosensitive organs as breast, gonads and eyes.

58 IAEA Radiation Protection in Paediatric Radiology L03.Radiation protection in screen-film radiography 58 References European Guidelines on Quality Criteria for Diagnostic Radiographic Images in Paediatrics, July EUR Available at: 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: Mooney and Thomas : Dose reduction in a paediatric X-ray department following optimization of radiographic technique, BJR (77) 1998: Cook, V., Radiation protection and quality assurance in paediatric radiology, Imaging, (13) 2001:229–238.


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