- Original Article
- Open Access
Gonad shielding in paediatric pelvic radiography: disadvantages prevail over benefit
© The Author(s) 2011
- Received: 4 June 2011
- Accepted: 9 September 2011
- Published: 25 September 2011
To re-evaluate gonad shielding in paediatric pelvic radiography in terms of attainable radiation risk reduction and associated loss of diagnostic information.
A study on patient dose and the quality of gonad shielding was performed retrospectively using 500 pelvic radiographs of children from 0 to 15 years old. In a subsequent study, 195 radiographs without gonad shielding were included. Patient doses and detriment adjusted risks for heritable disease and cancer were calculated with and without gonad shielding.
For girls, gonad shields were placed incorrectly in 91% of the radiographs; for boys, in 66%. Without gonad shielding, the hereditary detriment adjusted risk for girls ranged between 0.1 × 10−6 and 1.3 × 10−6 and for boys between 0.3 × 10−6 and 3.9 × 10−6, dependent on age. With shielding, the reduction in hereditary risk for girls was on average 6 ± 3% of the total risk of the radiograph, for boys 24 ± 6%. Without gonad shielding, the effective dose ranged from 0.008 to 0.098 mSv.
With modern optimised X-ray systems, the reduction of the detriment adjusted risk by gonad shielding is negligibly small. Given the potential consequences of loss of diagnostic information, of retakes, and of shielding of automatic exposure-control chambers, gonad shielding might better be discontinued.
- Radiation risk
Protection of the gonads against diagnostic X-rays gained ground in the 1950s [1–4]. Among the reasons were the increased radiation awareness caused by the genetic effects observed in irradiated fruit flies and the higher cancer incidence in the atomic bomb survivors. Both effects are supposed to be induced without a threshold dose [5, 6].
Gonad shielding in radiology has become common practice and is recommended by national and international bodies [7, 8]. The conditions for its application given in  are: “(a) The gonads will lie in the primary X-ray field or within close proximity (5 cm); (b) the clinical objectives of the examination will not be compromised; (c) the patient has a reasonable reproductive potential”.
Gonad shielding may be quite effective as it can lower the dose to the testes by about 95% and the dose to the ovaries by about 50% . The lower level of protection in females is mainly due to the large spread in the position of the ovaries, including areas far from the midline lying anterior to pelvic anatomy that has to be visible in the image [7, 9]. In the early years the attainable dose reduction was also high in an absolute sense, because the doses needed for imaging were high. In his 1953 review on the potential hazards of the use of X-rays in paediatrics, Miller  reported a patient entrance dose of about 12 mGy for a radiograph, and an entrance dose rate of 100–200 mGy/min during fluoroscopy. Fluoroscopy at that time was performed with the classical fluorescent screen, and it was often used instead of radiography, easily resulting in entrance doses of a few hundred mGy. Other investigators [10–12] reported similar dose values, but efforts to reduce patient dose were underway .
Unfortunately, the use of gonad protection is not only advantageous, as becomes clear from many evaluations that show that gonad shielding is poor in daily practice [14–21]. It appears to be very difficult to place the X-ray shield correctly, i.e. fully covering the target area but none of the bony pelvic structures. As a consequence, many images are suboptimal or worse, leading to loss of diagnostic information that impairs the radiologist’s work. Moreover, the dose reduction can be limited as well, or there may even be a dose increase.
Since the introduction of gonad shielding there have been major advances in X-ray imaging technology and radiation biology. The improved technology and optimisation of imaging protocols have resulted in much lower doses [22–31], while the risk for heritable disease has been found to be lower than previously assumed . The question then arises whether today’s reduction in radiation risk by applying gonad shielding is still worthwhile in view of its negative consequences. This balance has not been drawn up so far and as the outcome might have a large impact on daily practice, we decided to re-evaluate the benefit of gonad shielding in terms of attainable radiation risk reduction and associated loss of diagnostic information.
Optimisation as the incentive for this study
The three pillars of the radiation protection model of the International Commission on Radiological Protection (ICRP) are justification, optimisation and dose limits . To comply with the second obligation, optimisation, X-ray procedures should be re-evaluated from time to time. We performed such an evaluation of pelvic radiography in children, using data already available in our Picture Archiving and Communication System (PACS) (Kodak Carestream Health, Rochester, NY). Organ and effective doses, and the effect of gonad shielding on these doses, were calculated using PCXMC, a Monte Carlo program for estimating patient doses in medical X-ray examinations (STUK—Radiation and Nuclear Safety Authority, Helsinki, Finland). These calculations showed that gonad shielding (1 mm Pbeq., Dr. Goos-Suprema, Heidelberg, Germany) gave a trivial reduction of the already very small radiation risk. At the same time, we often observed a serious loss of diagnostic information caused by improper gonad shielding. On the basis of these findings the radiological staff unanimously decided to discontinue gonad shielding in paediatric pelvic imaging using X-rays. Realising that our results might be of wider interest and appropriate for publication, we extended our initial investigation with more data, obtained both before and after discontinuation of gonad shielding. This extended study is the subject of this article; with respect to its execution the Medical Ethics Committee of the Maastricht University Medical Center formally acknowledged that no medical ethical approval was required.
Patients and X-ray projection
In the first retrospective study we investigated gonad shielding and patient dose in children aged 0–15 years. The children had a standard anterior-posterior (AP) pelvic radiograph in 2007 or 2008, mostly in relation to congenital hip dysplasia. The projection covered the region from the iliac crests to 2 cm below the trochanter minor on the femur. Following the majority of other investigators [22–26, 33, 34], we distinguished age groups of 0–1 years, 1–5 years, 5–10 years and 10–15 years. Additional radiographs were evaluated in the second retrospective study in 2010 after we had stopped the application of gonad shields.
Image acquisition and storage
The pelvic radiographs had been acquired in three rooms, each equipped with an X-ray system using a digital flat panel detector (AXIOM Aristos FX Plus; Siemens, Erlangen, Germany). These systems have pre-programmed protocols, which set the high voltage (kVP), additional filter, focus to image-detector distance, and either a fixed tube current-exposure time product (mAs value) or the automatic exposure control (AEC). The protocol indicates whether the bucky anti-scatter grid has to be present or absent, but grid insertion or removal has to be done manually. We have no special team of technicians for paediatric radiology within our department.
For the younger patients, age-dependent protocols with fixed technique parameters are used. For the 10–15 age group different protocols are applied because the children of this age vary strongly in size. For the smaller patients no grid and no AEC are used, for the group of more adult sized patients they often are.
After acquisition, the images are “shuttered”, i.e. irrelevant edges of the images are removed digitally. Subsequently the images are sent to our PACS in Digital Imaging and Communications in Medicine (DICOM) format. The DICOM header contains retrievable information on the exposure [e.g. kVP, filter, mAs value, use of the grid and the air kerma-area product (KAP)]. Information on the use of the AEC is not stored, neither is the size of the unshuttered field of view.
Evaluation of gonad shielding
Because the quality of gonad shielding potentially has a large impact on the diagnostic information in the image and the dose reduction as well, the shielding was visually evaluated (by M.J.F.). For boys, the gonad shield had to fully cover the testes, while all bony pelvic parts remained uncovered. For girls, the central section of the pelvis had to be covered, again without shielding parts of the pelvic bones, with the exception of the sacrum to just below the sacro-iliac joints. The radiograph made during the patient’s very first visit to the department was obtained without shielding.
Judging from the presence of poor images, retakes had been limited to the absolute minimum. In the evaluation, we therefore identified also all images in which important diagnostic landmarks were not visible due to shielding. Specifically we considered assessability of Shenton’s line, Perkin’s lines and the acetabular angle (see Fawcett et al. , their Fig. 3); these studies were labelled as “retake required”, although no retake was obtained in reality. Unfortunately, the real number of retakes could not be determined.
We also estimated the fraction of the testes that was actually shielded (percent coverage) by visual inspection of the radiographs. The corresponding testes dose reduction was calculated with PCXMC as the dose to the testes due to an exposure with the size of the gonad shield, with the field overlaying “percent coverage” of the testes in the cranial-caudal direction. For girls, we assumed that protection is not very sensitive to positioning of the shield (in a statistical sense at least), because of the large spread in the position of the ovaries .
Determination of patient dose
In the first dosimetric study (data from 2007 and 2008) gonad shielding was standard, in the second study (data from 2010) shielding was absent.
Together with the discontinuation of the gonad shielding, we continued to optimise our protocols. In the first place, more guidance for the imaging of larger children (10–15 years) was introduced because of large differences in exposure within this group. Secondly, following the European Guidelines , we added an additional copper filter of 0.1 mm for the two intermediate age groups. For the youngest patients (0–1 years) the decrease in image quality was considered too large by the paediatric radiologist; for the 10–15 age group, the filter was already used.
The basic filtration of the X-ray beam (i.e. in the absence of 0.1 mm Cu) was determined from the measured half-value layer in aluminium. Since most authors had reported the entrance dose as a dose-in-air including backscatter [22, 23, 25–31], we followed this convention. We estimated backscatter factors for the conversion of incident air kerma to entrance dose for each age group and radiation quality using data from the NRPB report R279 . These factors were 1.26, 1.35, 1.39, 1.45 and 1.48 for the age groups 0–1 years, 1–5 years, 5–10 years, 10–15 years small childen and 10–15 years large children, respectively. The incident air kerma was derived by PCXMC from the KAP and the estimated unshuttered image size. Note that the dose in tissue, used in two publications [24, 33], is about 5% higher than the entrance dose as used by most other investigators and us.
Input information for PCXMC comprises imaging technique settings (kVp, filtration), KAP, image field size and projection. Note that these exposure parameters are generally independent of the use of gonad shielding, unless the shield was in front of an active AEC chamber. The effect of shielding is taken into account by subtracting a fraction of the gonad dose calculated for the no-shield exposure; under optimal circumstances this subtracted fraction amounts to 95% in male patients and 50% in female patients .
PCXMC has the option to adjust the size of the phantoms of all ages. The dose estimation in a specific age group of children will be illustrated using the 5–10 age group as an example. Rather than treating these children as a single group in the dose calculation, we considered 5- to 7.5-year-olds and 7.5- to 10-year-olds separately to reduce the potential effects of spread in patient size. By interpolation between data for child phantoms of different age present in PCXMC, we determined the weight and length of children of 6.25 and 8.75 years. Using the exposure parameters and interpolated patient size and weight for each subgroup, organ doses and effective dose were calculated with PCXMC for the 6.25- and 8.75-year-olds. The average dose for the 5–10 age group was then calculated by averaging the results for these two subgroups. Doses for other age groups were estimated in a similar fashion (always using two subgroups).
The problem of the collimator settings not being stored in the DICOM header (necessary as input on field size) was addressed by determining the average difference in width and height of the original (unshuttered) and shuttered images for a limited set of images for which both types of data were retained. Considerable variations in measured differences existed, but on average 1 cm had to be added in all four directions to compensate for the shuttering. Although this correction for shuttering is necessarily approximate, its application was preferred over leaving it out as this systematically would overestimate the entrance dose. To derive the effective dose from organ doses, the tissue-weighting factors published in ICRP 103 were chosen in PCXMC.
As gonad shielding is applied to limit hereditary effects, the detriment adjusted risk for heritable disease was estimated (the ‘detriment adjusted risk’ takes the various potential, negative consequences of the exposure into account, weighting for the seriousness of the corresponding harms; for the official definition see ICRP 103 ).
Because we saw no solution to the problem of translating the loss of diagnostic information into a numerical risk that might be compared with the risk of radiation, we limited the quantitative risk analysis to radiation effects only.
Shortcomings of gonad shielding, which manifest themselves inevitably in daily practice, and which have an impact on the patient dose, are: (1) in males, an incomplete coverage of the testes, (2) the need for retakes because vital landmarks are obscured and (3) an increase in dose when an active AEC-chamber is (partly) shielded by the lead supposed to shield the gonads. Only point 1 was taken into account, the other two were not, because of missing information.
The detriment adjusted hereditary risk of a pelvic radiograph can be calculated using the nominal coefficient of 5.4 × 10-3 Sv-1 for persons of reproductive age . For the computation of the total detriment adjusted risk, the risk coefficient for cancer (5.5 × 10-2 Sv-1 for the whole population ) with an age-dependent correction for the higher cancer risk for children  is needed as well. These calculations further require the effective dose, the testes dose and the dose to the ovaries. The reduction of hereditary risk achieved by gonad shielding was also expressed as a percentage of the total risk of a radiograph obtained without shielding.
Summary of gonad shielding during paediatric AP pelvic radiography in the period 2007-2008
Male (na = 193)
Female (na = 307 )
Shielding incorrectb (%)
Retakes requiredc (%)
Shielding incorrectb (%)
Retakes requiredc (%)
Over the whole range of 0-100% coverage of the testes, the average dose reduction decreased with increasing age (and kVp) from approximately 0.98 to 0.90 times the coverage. So for practical purposes, the fractional testes dose reduction is equal to the fractional coverage. The actual reduction in testes dose, taking this partial shielding into account, is for boys of 0–1 years 51%, 1–5 years 54%, 5–10 years 76% and 10–15 years 77%. For girls, the literature value of 50% was assumed as explained above.
Imaging technique settings in AP pelvic radiographya
Mean dose data AP pelvic radiography in absence of gonad shielding (n = 195)
Incident air kerma
Effective dose ICRP 103
Organ dose testicles
Organ dose ovaries
Contribution of gonads to effective dose
18.8 ± 7.8
16.6 ± 6.3
49 ± 28
168 ± 125
369 ± 156
Detriment adjusted risks caused by AP pelvic radiography with and without gonad shielding
Total risk without shielding
Hereditary risk without shielding
Hereditary risk with shielding
The absolute magnitude of the reduction in hereditary risk, even assuming complete uncompromised shielding of the gonads, was very small. Several factors are responsible for this finding. First of all, technical developments and protocol optimisation have lowered the dose needed for a pelvic radiograph from about 10 mGy in the 1950s to a few tenths of a milligray today. Secondly, the risk coefficient for heritable disease is considerably lower than previously assessed.
Gonad shield positioning in pelvic radiography according to various studies
Number of radiographs with shielding
Percentage with incorrectly placed shields
Kenny and Hill 
McCarty et al. 
Sikand et al. 
Gul et al. 
Masud et al. 
Fawcett and Barter
McManus and Davis 
Mean entrance doses in air, including backscatter, in pelvic radiography according to studies in the past two decades
Ruiza et al. 
Martin et al. 
Kyriou et al. 
McDonalda et al. 
Mooney and Thomas
Hufton et al. 
Gogosb et al. 
Azevedo et al. 
Yakoumakisb et al. 
Kiljunenc et al. 
Sulimand and Elshiekh 
Table 6 also shows considerable spread in doses. Thirteen out of 15 reported entrance doses for 0 to 1-year-old children are lower than the diagnostic reference level (DRL) of 640 μGy given in the European Guidelines  for 4-month old infants, while 12 out of 15 values for 1 to 5-year-old children are below the DRL of 924 μGy for 5-year-olds. Smans et al.  reported data from a European survey that do not fit in Table 6 due to a different age grouping. Their doses include a low median value of 48 μGy for children younger than 1 year and quite a high mean value of 3,460 ± 2,730 μGy for 8 to 12-year-olds. The large spread and the many high values reported in the literature indicate that a lot is still to be gained by optimisation. This issue is currently being addressed in many countries by setting DRLs for frequently performed procedures, as recommended by the ICRP [32, 38]. Discontinuation of gonad protection should not be considered before optimisation has been performed and dose levels in the low range of Table 6 have been realised. Installation of a modern digital system is no guarantee for acceptable performance.
Patient dose reductions since the fifties were realised by using harder radiation, a larger focus-patient distance, the introduction of faster screens and films, and the discontinuation of fluoroscopy in favour of radiography. In fluoroscopy the introduction of the image intensifier was a major step. Recently the more sensitive digital detectors and the concomitant development of image processing software helped reduce patient dose.
Despite its limitations, gonad shielding has served its purpose in times when doses were high. Now it appears that its potential advantages are outweighed by the drawbacks. Too many images contain impaired diagnostic information. The high numbers of retakes required, but not actually taken, are symptomatic. Often the radiologist is forced to fill in the gaps with information from previous images. This is not without risk, as illustrated by the incident with the shielded osteomyelytic lesion ( Fig. 1). This incident shows that even the peripheral zones of pelvic bones should not be covered.
The uncertainties in the derived doses still need to be considered. The KAP meters are calibrated on a regular basis and their accuracy is typically within 5-10%. PCXMC has only a limited number of mathematical phantoms, and the size of the individual patient may not correspond to that of the phantom closest in age. As a consequence, in some cases PCXMC’s dose estimates will be too high, and in others too low, but the average dose estimate for patients within an age group will be fairly realistic. The correction for shuttering to obtain the true X-ray field size introduces an additional uncertainty in the dose estimates. To give an idea of its magnitude, assume that the uncertainty equals the fully applied correction of 1 cm in all directions. This would result in an uncertainty of the estimated area of ±13% for the smallest and ±6% of the largest fields. Note that for a given KAP the effect of a change in the beam area on the effective dose is likely to be small, but on the dose to the gonads (or any other single organ) it will have its full impact. Taking all considerations together, the accuracy of the average calculated dose should be better than about 20%. For individual patients the error may be larger, as indicated by the spread in KAP values in Table 3.
An important practical aspect for this discussion is the perception of radiation risks. The emphasis over the years on applying gonad shields has nurtured the conviction that major risks have to be countered. Workers and parents are so used to shielding that not using it is considered a major neglect. And it cannot be denied that there is an average risk reduction for boys of about 24% and of 6% for girls, so why stop protection? The answer is given by the ICRP, which advises that risks in the range 10−6-10-7 be considered as of no concern . Only for the group of large boys of age 10–15 years is the potential reduction in hereditary (or total) risk 3.0 × 10−6.
The effect of a few trivial activities in all-day life on effective dosea
Lowering radon (222Rn) concentration at home with 1 Bq/m3 
(e.g. by increasing ventilation; worldwide average conc. 40 Bq/m3)
Holidays on a cruise ship instead of on land 
Large distance flying 
Visit of cave with relatively low radon concentration of 1 kBq/m3 
Person living in Cornwall (6.5 mSv/year due to radon only) going
to London (1 mSv/year) 
Living in The Netherlands (2 mSv/year)
There are good arguments to stop gonad protection in pelvic radiography of children, provided modern equipment and properly optimised imaging protocols are used. The risk reduction for girls and young boys is marginal, for older boys there is room for discussion. Our staff decided upon images of constant good quality, for all children, rather than the minor benefit of gonad protection. Available resources for education and optimisation are better directed at applications with a potentially higher risk reduction.
- Abram E, Wilkinson DM, Hodson CJ (1958) Gonadal protection from X radiation for the female. Br J Radiol 31:335–336PubMedView ArticleGoogle Scholar
- Ardran GM, Kemp FH (1957) Protection of the male gonads in diagnostic procedures. Br J Radiol 30:280View ArticleGoogle Scholar
- Whitehead G, Griffiths JT (1961) The Leicester gonad protector: a device to afford localised protection from diagnostic x-irradiation. Br J Radiol 34:135–136PubMedView ArticleGoogle Scholar
- Lorenz W (1958) Physical and technical problems of radiation protection in medical installations. Fortschr Geb Rontgenstr Nuklearmed 88:251–276PubMedView ArticleGoogle Scholar
- Meggitt G (2008) Taming the rays—a history of radiation and protection. Raleigh, Lulu.comGoogle Scholar
- Miller RW (1953) Some potential hazards of the use of roentgen rays in pediatrics. Pediatrics 11:294–303PubMedGoogle Scholar
- International Commission on Radiological Protection (1982) Protection of the patient in diagnostic radiology (ICRP publication 34). Ann. ICRP 1982;9 (2–3), Pergamon, OxfordGoogle Scholar
- FDA. 21 CFR 1000.50 (1976) Recommendation for the use of specific area gonad shielding on patients during medical diagnostic x-ray procedures Available via http://cfr.vlex.com/vid/1000-recommendation-gonad-shielding-patients-ray-19716085. Accessed 27 Oct 2010
- Bardo DM, Black M, Schenk K, Zaritzky MF (2009) Location of the ovaries in girls from newborn to 18 years of age: reconsidering ovarian shielding. Pediatr Radiol 39:253–259PubMedView ArticleGoogle Scholar
- Stanford RW, Vance J (1955) The quantity of radiation received by the reproductive organs of patients during routine diagnostic x-ray examinations. Br J Radiol 28:266–273PubMedView ArticleGoogle Scholar
- Martin JH (1947) Radiation doses received by the skin of a patient during routine diagnostic X-ray examinations. Br J Radiol 20:279–283PubMedView ArticleGoogle Scholar
- Billings MS, Norman A, Greenfield MA (1957) Gonad dose during routine roentgenography. Radiology 69:37–41PubMedView ArticleGoogle Scholar
- Ardran GM (1956) The hazards from the increasing use of ionizing radiations II. The dose to the operator and patient in x-ray diagnostic procedures. Br J Radiol 29:266–269PubMedView ArticleGoogle Scholar
- Kenny N, Hill J (1992) Gonad protection in young orthopaedic patients. BMJ 304:1411–1413PubMedPubMed CentralView ArticleGoogle Scholar
- Wainwright AM (2000) Shielding reproductive organs of orthopaedic patients during pelvic radiography. Ann R Coll Surg Engl 82:318–321PubMedPubMed CentralGoogle Scholar
- McCarty M, Waugh R, McCallum H, Montgomery RJ, Aszkenasy OM (2001) Pediatric pelvic imaging: improvement in gonad shield placement by multidisciplinary audit. Pediatr Radiol 31:646–649PubMedView ArticleGoogle Scholar
- Sikand M, Stinchcombe S, Livesley PJ (2003) Study on the use of gonadal protection shields during paediatric pelvic X-rays. Ann R Coll Surg Engl 85:422–425PubMedPubMed CentralView ArticleGoogle Scholar
- Gul A, Zafar M, Maffulli N (2005) Gonadal shields in pelvic radiographs in pediatric patients. Bull Hosp Jt Dis 63:13–14PubMedGoogle Scholar
- Masud S, Mehra A, Clothier JC (2008) Study on the use of gonadal shields in paediatric pelvic x-rays. J Bone Joint Surg Br 90-B (Suppl II):338Google Scholar
- Fawcett SL, Barter SJ (2009) The use of gonad shielding in paediatric hip and pelvis radiographs. Br J Radiol 82:363–370PubMedView ArticleGoogle Scholar
- McManus A, Davis N (2010) The gonad shield in pelvic X-rays covering a multitude of sins? Available via http://www.epos.efort.org/public/Sorrentoeposters/3958.ppt. Accessed 27 Oct 2010
- Martin CJ, Farquhar B, Stockdale E, MacDonald S (1994) A study of the relationship between patient dose and size in paediatric radiology. Br J Radiol 67:864–871PubMedView ArticleGoogle Scholar
- Kyriou JC, Fitzgerald M, Pettett A, Cook JV, Pablot SM (1996) A comparison of doses and techniques between specialist and non-specialist centres in the diagnostic X-ray imaging of children. Br J Radiol 69:437–450PubMedView ArticleGoogle Scholar
- McDonald S, Martin CJ, Darragh CL, Graham DT (1998) Dose-area product measurements in paediatric radiography. Br J Radiol 69:318–325View ArticleGoogle Scholar
- Mooney R, Thomas PS (1998) Dose reduction in a paediatric X-ray department following optimization of radiographic technique. Br J Radiol 71:852–860PubMedView ArticleGoogle Scholar
- Hufton AP, Doyle SM, Carty HM (1998) Digital radiography in paediatrics: radiation dose considerations and magnitude of possible dose reduction. Br J Radiol 71:186–199PubMedView ArticleGoogle Scholar
- Gogos KA, Yakoumakis EN, Tsalafoutas IA, Makri TK (2003) Radiation dose considerations in common paediatric X-ray examinations. Pediatr Radiol 33:236–240PubMedView ArticleGoogle Scholar
- Yakoumakis EN, Tsalafoutas IA, Aliberti M, Pantos GI, Yakoumakis NE, Karaiskos P, Georgiou EK (2007) Radiation doses in common X-ray examinations carried out in two dedicated paediatric hospitals. Radiat Prot Dosimetry 124:348–352PubMedView ArticleGoogle Scholar
- Kiljunen T, Tietäväinen A, Parviainen T, Viitala A, Kortesniemi M (2009) Organ doses and effective doses in pediatric radiography: patient-dose survey in Finland. Acta Radiol 50:114–124PubMedView ArticleGoogle Scholar
- Suliman II, Elshiekh EH (2008) Radiation doses from some common paediatric X-ray examinations in Sudan. Radiat Prot Dosimetry 132:64–72PubMedView ArticleGoogle Scholar
- Smans K, Vaño E, Sanchez R, Schultz FW, Zoetelief J, Kiljunen T, Maccia C, Järvinen H, Bly R, Kosunen A, Faulkner K, Bosmans H (2008) Results of a European survey on patient doses in paediatric radiology. Radiat Prot Dosimetry 129:204–210PubMedView ArticleGoogle Scholar
- International Commission on Radiological Protection (2007) The 2007 recommendations of the International Commission on Radiological Protection (ICRP publication 103). Ann ICRP 37(2–4), Pergamon, OxfordGoogle Scholar
- Ruiz MJ, González L, Vañó E, Martínez A (1991) Measurement of radiation doses in the most frequent simple examinations in paediatric radiology and its dependence on patient age. Br J Radiol 64:929–933PubMedView ArticleGoogle Scholar
- Azevedo AC, Osibote OA, Boechat MC (2006) Paediatric x-ray examinations in Rio de Janeiro. Phys Med Biol 51:3723–3732PubMedView ArticleGoogle Scholar
- Commission for European Communities (1996) European Guidelines on quality criteria for diagnostic images in paediatrics (EUR-16261)Google Scholar
- Hart D, Jones DG, Wall BF (1996) Coefficients for estimating effective doses from paediatric x-ray examinations. Chilton, NRPB-R279. HMSO, LondonGoogle Scholar
- International Commission on Radiological Protection (1991) 1990 recommendations of the International Commission on Radiological Protection (ICRP publication 60). Ann ICRP 21(1–3). Pergamon, OxfordGoogle Scholar
- International Commission on Radiological Protection (2007) Radiological protection in medicine (ICRP publication105). Ann ICRP 37(6), Pergamon, OxfordGoogle Scholar
- International Commission on Radiological Protection (2006) ICRP supporting guidance 5. Ann. ICRP 35(4), Pergamon, OxfordGoogle Scholar
- National Council on Radiation Protection and Measurements (NCRP) (1993) Limitation of Exposure to Ionizing Radiation. Report No. 116, NCRP Publications, BethesdaGoogle Scholar
- Traffic collision. Wikipedia. http://en.wikipedia.org/wiki/Traffic_collision. Accessed 18 July 2011.
- Report of the United Nations Scientific Committee on the Effects of Atomic Radiation (2000) UNSCEAR 2000 Report to the General Assembly, with scientific annexes. Vol. I, Annex B, Exposures from natural radiation sources. United Nations, New YorkGoogle Scholar
- Fact Sheet on U.S. Nuclear Powered Warship (NPW) Safety. Available via http//www.mofa.go.jp/region/n-america/us/security/fact0604.pdf Note the dose given in this Fact Sheet is equal to that due to cosmic radiation at sea level. Accessed 30 Oct 2010
- Federal Aviation Administration Office of Aerospace Medicine, Civil Aerospace Medical Institute (2010) Available via http://jag.cami.jccbi.gov/cariresults.asp. Accessed 28 Oct 2010
- Lario J, Sánchez-Moral S, Cañaveras JC, Cuezva S, Soler V (2005) Radon continuous monitoring in Altamira Cave (northern Spain) to assess user's annual effective dose. J Environ Radioact 80:161–174PubMedView ArticleGoogle Scholar
- Watson SJ, Jones AL, Oatway WB, Hughes JS (2005) Ionising radiation exposure of the UK population: 2005 Review. HPA-RPD-001. Available via http://www.hpa.org.uk/Publications/Radiation/HPARPDSeriesReports/HpaRpd001/. Accessed 28 Oct 2010
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