IAEA survey of pediatric CT practice in 40 countries in Asia, Europe, Latin America, and Africa: Part 1, frequency and appropriateness

Results and analysis of examination doses for paediatric CT procedures based on a nationwide survey in China

OBJECTIVE

To report the results of a dose survey conducted across 31 provinces in mainland China from 2017 to 2018 and to analyse the dose level to determine the national diagnostic reference levels (DRLs) for paediatric CT procedures.

METHODS

At least ten patients for each age group (0- < 1, 1- < 5, 5- < 10, 10- < 15 years) and each procedure (head, chest and abdomen) for each CT scanner were selected from four to eight hospitals in each province. The dose information (CTDIvol and DLP) was collected from the HIS or RIS-PACS systems. The median values in each CT scanner were considered the representative dose values for the paediatric patients in CT scanning. The national DRLs were estimated based on the 75th percentile distribution of the median values.

RESULTS

A total of 24,395 patients and 319 CT scanners were investigated across 262 hospitals. For paediatric CT scanning in 4 different age groups, the median (P50) and the 75th percentile (P75) of CTDIvol and DLP for each scanning procedure were calculated and reported. National DRLs were then proposed for each procedure and age group.

CONCLUSION

The dose level of CT scanning for children in mainland China was reported for the first time. The DRLs for paediatric CT in the present study are similar to those in some Asian countries but higher than those in European countries.

CLINICAL RELEVANCE STATEMENT

The paediatric CT is an extensively used tool in diagnosing paediatric disease; however, children are more sensitive to radiation. Establishing the diagnostic reference level of paediatric CT examination is necessary to reduce the dose of CT in children and promote the optimisation of medical exposure.

KEY POINTS

• The DRLs for 3 paediatric CT procedures (head, chest and abdomen) and 4 age groups (0- < 1, 1- < 5, 5- < 10, 10- < 15 years) were proposed in mainland China first time. • The examination parameter and dose for children need to be further optimised in China, especially to lower the tube voltage in paediatric CT.

[Scientific Research Group Report: Nationwide Survey on Radiation Exposure of Pediatric CT Examination in Japan (2018)]

PURPOSE

To understand the latest pediatric computed tomography (CT) exposure required for the revision of national DRLs.

METHODS

A questionnaire was sent to 409 facilities where the members of the Japanese Society of Radiological Technology and the Japanese Society of Pediatric Radiology are enrolled. We investigated the imaging conditions, CTDI_vol, and DLP of the pediatric head, chest, and abdominal CT examinations.

RESULTS

In all, 43 facilities (11%) responded to our survey. multi detector-row CT (MDCT) systems were available in all surveyed facilities. More than 98% of the MDCT systems had more than 64 detector rows. The CTDI_vol of all CT protocols was lower than the NDRL due to the progress of updating to MDCTs with radiation exposure reduction functions such as an iterative reconstruction, but the DLP of head and abdominal CT protocols of some age group were higher than NDRL.

CONCLUSION

It is necessary to review the imaging protocol with the attending physician and radiologist and consider further optimization of medical exposure.

Size-specific dose estimates (SSDEs) for computed tomography and influencing factors on it: a systematic review

The actual dose received during a computed tomography (CT) examination depends on both the patient size and the radiation output of the scanner. To represent the actual patient morphometry, a new radiation dose metric named size-specific dose estimates (SSDEs) was developed by the American Association of Physicists in Medicine in 2011. The purpose of this article is to review the SSDE concept and the factors influencing it. Moreover, the appropriate methodology of SSDE determination and the application of SSDE as a diagnostic reference-level quantity is critically analyzed based on the data available in the literature. It is expected that this review could potentially increase awareness among CT users of the effective utilization of SSDE as a tool to aid in the optimization of radiation dose in CT.

Epidemiological studies of CT scans and cancer risk: the state of the science

20 years ago, 3 manuscripts describing doses and potential cancer risks from CT scans in children raised awareness of a growing public health problem. We reviewed the epidemiological studies that were initiated in response to these concerns that assessed cancer risks from CT scans using medical record linkage. We evaluated the study methodology and findings and provide recommendations for optimal study design for new efforts. We identified 17 eligible studies; 13 with published risk estimates, and 4 in progress. There was wide variability in the study methodology, however, which made comparison of findings challenging. Key differences included whether the study focused on childhood or adulthood exposure, radiosensitive outcomes (e.g. leukemia, brain tumors) or all cancers, the exposure metrics (e.g. organ doses, effective dose or number of CTs) and control for biases (e.g. latency and exclusion periods and confounding by indication). We were able to compare results for the subset of studies that evaluated leukemia or brain tumors. There were eight studies of leukemia risk in relation to red bone marrow (RBM) dose, effective dose or number of CTs; seven reported a positive dose-response, which was statistically significant (p < 0.05) in four studies. Six of the seven studies of brain tumors also found a positive dose-response and in five, this was statistically significant. Mean RBM dose ranged from 6 to 12 mGy and mean brain dose from 18 to 43 mGy. In a meta-analysis of the studies of childhood exposure the summary ERR/100 mGy was 1.78 (95%CI: 0.01-3.53) for leukemia/myelodisplastic syndrome (n = 5 studies) and 0.80 (95%CI: 0.48-1.12) for brain tumors (n = 4 studies) (p-heterogeneity >0.4). Confounding by cancer pre-disposing conditions was unlikely in these five studies of leukemia. The summary risk estimate for brain tumors could be over estimated, however, due to reverse causation. In conclusion, there is growing evidence from epidemiological data that CT scans can cause cancer. The absolute risks to individual patients are, however, likely to be small. Ongoing large multicenter cohorts and future pooling efforts will provide more precise risk quantification.

Motion estimation and correction in SPECT, PET and CT

Patient motion impacts single photon emission computed tomography (SPECT), positron emission tomography (PET) and X-ray computed tomography (CT) by giving rise to projection data inconsistencies that can manifest as reconstruction artifacts, thereby degrading image quality and compromising accurate image interpretation and quantification. Methods to estimate and correct for patient motion in SPECT, PET and CT have attracted considerable research effort over several decades. The aims of this effort have been two-fold: to estimate relevant motion fields characterizing the various forms of voluntary and involuntary motion; and to apply these motion fields within a modified reconstruction framework to obtain motion-corrected images. The aims of this review are to outline the motion problem in medical imaging and to critically review published methods for estimating and correcting for the relevant motion fields in clinical and preclinical SPECT, PET and CT. Despite many similarities in how motion is handled between these modalities, utility and applications vary based on differences in temporal and spatial resolution. Technical feasibility has been demonstrated in each modality for both rigid and non-rigid motion, but clinical feasibility remains an important target. There is considerable scope for further developments in motion estimation and correction, and particularly in data-driven methods that will aid clinical utility. State-of-the-art machine learning methods may have a unique role to play in this context.

A comparative study on dispersed doses during photon and proton radiation therapy in pediatric applications

The Monte Carlo method was employed to simulate realistic treatment situations for photon and proton radiation therapy for a set of Oak Ridge National Laboratory (ORNL) pediatric phantoms for 15, 10, 5 and 1-year olds as well as newborns. Complete radiotherapy situations were simulated using the previously developed NRUrad input code for Monte Carlo N-Particle (MCNP) code package. Each pediatric phantom was irradiated at five different positions, namely, the testes, colon, liver, left lung and brain, and the doses in targeted organs (Dt) were determined using the track length estimate of energy. The dispersed photon and proton doses in non-targeted organs (Dd), namely, the skeleton, skin, brain, spine, left and right lungs were computed. The conversion coefficients (F = Dd/Dt) of the dispersed doses were used to study the dose dispersion in different non-targeted organs for phantoms for 15, 10, 5 and 1-year olds as well as newborns. In general, the F values were larger for younger patients. The F values for non-targeted organs for phantoms for 1-year olds and newborns were significantly larger compared to those for other phantoms. The dispersed doses from proton radiation therapy were also found to be significantly lower than those from conventional photon radiation therapy. For example, the largest F values for the brain were 65.6% and 0.206% of the dose delivered to the left lung (P4) for newborns during photon and proton radiation therapy, respectively. The present results demonstrated that dispersion of photons and generated electrons significantly affected the absorbed doses in non-targeted organs during pediatric photon therapy, and illustrated that proton therapy could in general bring benefits for treatment of pediatric cancer patients.

Clinical use and indications for head computed tomography in children presenting with acute medical illness in a low- and middle-income setting

BACKGROUND

Computed tomography (CT) imaging is an indispensable tool in the management of acute paediatric neurological illness providing rapid answers that facilitate timely decisions and interventions that may be lifesaving. While clear guidelines exist for use of CT in trauma to maximise individual benefits against the risk of radiation exposure and the cost to the healthcare system, the same is not the case for medical emergency.

AIMS

The study primarily aimed to retrospectively describe indications for non-trauma head CT and the findings at a tertiary paediatric hospital.

METHODS

Records of children presenting with acute illness to the medical emergency unit of Red Cross War Children's Hospital, Cape Town, over one year (2013) were retrospectively reviewed. Participants were included if they underwent head CT scan within 24 hours of presentation with a non-trauma event. Clinical data and reports of CT findings were extracted.

RESULTS

Inclusion criteria were met by 311 patients; 188 (60.5%) were boys. The median age was 39.2 (IQR 12.6-84.0) months. Most common indications for head CT were seizures (n = 169; 54.3%), reduced level of consciousness (n = 140;45.0%), headache (n = 74;23.8%) and suspected ventriculoperitoneal shunt (VPS) malfunction (n = 61;19.7%). In 217 (69.8%) patients CT showed no abnormal findings. In the 94 (30.2%) with abnormal CT results the predominant findings were hydrocephalus (n = 54;57.4%) and cerebral oedema (n = 29;30.9%). Papilloedema was more common in patients with abnormal CT (3/56; 5.4%) compared with none in those with normal CT; P = 0.015; while long tract signs were found in 42/169 (24.9%) and 23/56 (41.1%) of patients with normal and abnormal CT findings, respectively; P = 0.020. Post-CT surgery was required by 47(15.1%) of which 40 (85.1%) needed a ventricular drainage. A larger proportion of patients with VPS (25/62; 40.3%) required surgery compared to patients without VPS (22/249; 8.8%; P<0.001).

CONCLUSION

A majority of head CT scans in children with medical emergency with acute neurological illness were normal. Patients with VPS constituted the majority of patients with abnormal CT scans that required subsequent neurosurgical intervention. Evidence-based guidelines are required to guide the best use of head CT in the management of children without head trauma.

Consensus survey on pre-procedural safety practices in radiological examinations: a multicenter study in seven Asian regions

OBJECTIVE

To understand the status of pre-procedural safety practices in radiological examinations at radiology residency training institutions in various Asian regions.

METHODS

A questionnaire based on the Joint Commission International Accreditation Standards was electronically sent to 3 institutions each in 10 geographical regions across 9 Asian countries. Questions addressing 45 practices were divided into 3 categories. A five-tier scale with numerical scores was used to evaluate safety practices in each institution. Responses obtained from three institutions in the United States were used to validate the execution rate of each surveyed safety practice.

RESULTS

The institutional response rate was 70.0% (7 Asian regions, 21 institutions). 44 practices (all those surveyed except for the application of wrist tags for identifying patients with fall risks) were validated using the US participants. Overall, the Asian participants reached a consensus on 89% of the safety practices. Comparatively, most Asian participants did not routinely perform three pre-procedural practices in the examination appropriateness topic.

CONCLUSION

Based on the responses from 21 participating Asian institutions, most routinely perform standard practices during radiological examinations except when it comes to examination appropriateness. This study can provide direction for safety policymakers scrutinizing and improving regional standards of care.

ADVANCES IN KNOWLEDGE

This is the first multicenter survey study to elucidate pre-procedural safety practices in radiological examinations in seven Asian regions.

DOSE BENCHMARKS FOR PAEDIATRIC HEAD COMPUTED TOMOGRAPHY EXAMINATION IN NIGERIA

Diagnostic reference levels (DRLs) provide benchmarks for dose optimisation. We aimed to propose DRLs for paediatric head computed tomography (CT) in Nigeria and assess if facilities adapt protocols to age-specific standardisations. Volume CT dose index (CTDIvol) and dose-length-product (DLP) of at least 20 paediatric patients per age group were extracted from 11 facilities and used to propose DRLs. Kruskal-Wallis and Median tests were used to assess the contribution of age to paediatric dose variations. CTDIvol (mGy)/DLP (mGy.cm) ranged 16-31/100-1603 (newborn), 10-92/75-4072 (1-y-old), 10-81/169-2603 (5-y-olds) and 14-86/119-3945 (≥10-y-olds). The 75th percentile CTDIvol/DLP values were 27/1040, 37/988, 48/1493 and 54/1824 for newborn, 1-y, 5-y, ≥10-y-olds, respectively. Age accounted for 18.4 and 5.3% variations in median CTDIvol and DLP, respectively. Paediatric head CT doses in Nigeria are higher than reported internationally, suggesting a need for dose optimisation interventions.

RADIATION DOSE DETERMINATION IN ABDOMINAL CT EXAMINATIONS OF CHILDREN AT SUDANESE HOSPITALS USING SIZE-SPECIFIC DOSE ESTIMATES

In this study, we thought to estimate the radiation exposure of children undergoing multi-detector CT examinations using size-specific dose estimates (SSDE). Console-displayed volume computed tomography dose index (CTDIvol) were recorded for a total of 78 paediatric abdominal CT examinations performed in six hospitals. Measurements of the patient diameters were taken from the mid-slice location on the transverse and scout CT images. Size-specific conversion coefficients were used to translate CTDIvol to the SSDE, according AAPM Report 204. For children aged 0-1 y, CTDIvol, SSDEtrans (from transverse images) and SSDEsco (from scout images) were: 12.80 ± 16.10, 14.43 ± 13.22; and 14.37 ± 13.03 mGy; respectively. For children aged 1-5 y, CTDIvol, SSDEtrans and SSDEsco were: 12.11 ± 14.47, 18.8 ± 18.61 and 16.51 ± 13.55 mGy; respectively. The obtained doses are higher than the corresponding diagnostic reference levels. SSDE increase with patient size as results of tube current modulation and is therefore a valuable tool for dose optimisation.

A survey of pediatric CT doses in the Shanghai metropolitan area

The purpose of this study was to evaluate computed tomography (CT) doses in child examinees at different ages throughout the Shanghai metropolitan area. The head and body CT dose indices (CTDIs) of 50 CT scanners were tested by phantom measurements using standard imaging protocols. The values of CTDI_w, CTDI_vol and dose length product (DLP) were calculated and saved in a table along with the parameters of routine head and chest scans for different age groups of children and adults. The effective doses were estimated from the K-factors by age and DLP. The CTDI_vol, DLP and effective dose for multi-detector row CT (MDCT) in children during routine head scans were larger than those for single-detector row CT (SDCT) and dual-detector row CT (DDCT). The CTDI_vol, DLP and effective dose for MDCT and DDCT in children during routine chest scans were lower than those for SDCT. Radiation risks are higher for children in CT examinations compared to adults.

DIRECT MEASUREMENTS OF SKIN, EYE LENS AND THYROID DOSE DURING PEDIATRIC BRAIN CT EXAMINATIONS

Pediatric brain computed tomography (CT) is identified as the most frequent CT examination in children. The aim of the study is the direct measurement of skin, eye lens and thyroid dose in pediatric patients during brain CT examinations. The study included 35 pediatric patients who underwent brain CT examinations. The patients were categorized in three age groups: Group A (age range: 0.8-1 years), Group B (age range: 2.0-4.9 years) and Group C (age range: 5.5-15.5 years). thermoluminescent dosimeters (TLDs) were placed on the eyes, the frontal region of the head, the mastoid apophysis and the thyroid gland. The skin dose was found 16.6 ± 1.5, 38.8 ± 5.1 and 41.7 ± 9.4 mGy for Groups A, B and C, respectively. The mean dose for the eye lens was 10.5 ± 3.3, 29.9 ± 8.6 and 34.2 ± 14.9 mGy and for the thyroid 1.7 ± 0.4, 2.4 ± 0.5 and 1.9 ± 0.4 mGy for Groups A, B and C, respectively. In vivo dosimetry using TLDs proved to be an efficient method. Gantry tilting and patient's set-up seem to significantly affect eye lens dose.

Development of a paediatric head voxel model database for dosimetric applications

OBJECTIVE

To develop a database of paediatric head voxel models intended for Monte Carlo (MC) dosimetric applications.

METHODS

Seventeen head and neck CT image data sets were retrieved from the picture archiving and communicating system of our hospital and were reformed into voxel models. 22 organs were segmented at each data set. The segmented organ masses were compared to the respective age- and gender-specific ICRP reference mass value. Adjustments were made such that segmented and reference mass values coincide within a tolerance of 10%. A dental cone beam CT cleft palate simulation study was set up to demonstrate the applicability of our database to MC frameworks and to investigate the need for age- and gender-specific paediatric models.

RESULTS

The designed database covers the age range from 2 months to 14 years old. Each model represents a reference head voxel phantom for its corresponding age and gender category. The simulation study revealed absorbed organ dose differences larger than 50% among the 5, 8 and 12 years old models when exposed to identical conditions.

CONCLUSION

Children cannot be represented by one average phantom covering the entire age range like adults due to the fact that their organs change rapidly in size and shape. A database of paediatric head voxel models was designed to enable dose calculations via MC simulations. Advances in knowledge: The application of each model of the database to MC frameworks provides age- and gender-specific organ dose estimations from medical exposures in the head and neck region.

Size-based quality-informed framework for quantitative optimization of pediatric CT

The purpose of this study was to formulate a systematic, evidence-based method to relate quantitative diagnostic performance to radiation dose, enabling a multidimensional system to optimize computed tomography imaging across pediatric populations. Based on two prior foundational studies, radiation dose was assessed in terms of organ doses, effective dose ([Formula: see text]), and risk index for 30 patients within nine color-coded pediatric age-size groups as a function of imaging parameters. The cases, supplemented with added noise and simulated lesions, were assessed in terms of nodule detection accuracy in an observer receiving operating characteristic study. The resulting continuous accuracy-dose relationships were used to optimize individual scan parameters. Before optimization, the nine protocols had a similar [Formula: see text] of [Formula: see text] with accuracy decreasing from 0.89 for the youngest patients to 0.67 for the oldest. After optimization, a consistent target accuracy of 0.83 was established for all patient categories with [Formula: see text] ranging from 1 to 10 mSv. Alternatively, isogradient operating points targeted a consistent ratio of accuracy-per-unit-dose across the patient categories. The developed model can be used to optimize individual scan parameters and provide for consistent diagnostic performance across the broad range of body sizes in children.

Review of the current status of radiation protection in diagnostic radiology in Africa

The aim of this paper is to review the available published studies from African countries on patient doses and medical radiation protection and identify strengths, weaknesses, and challenges. Papers on radiation doses to patients published until 2016 pertaining to studies in African countries were reviewed. Radiography, interventional radiology, computed tomography (CT), and mammography modalities were covered. In radiography, the entrance surface air kerma values were below the established diagnostic reference levels (DRLs) provided by the International Atomic Energy Agency, European Commission, and National Council on Radiation Protection and Measurements. Patient and staff doses in interventional procedures were not on the higher side when compared with other published reports from developed countries. The dose length product values in CT in many situations were higher than established DRLs. In mammography, the variations of clinical image quality and dose to standard breast between African countries and other countries were insignificant. In conclusion, like in any continent, not all countries in Africa are active, but some have produced good results. The potential for optimization of radiation protection using simple and inexpensive techniques has been demonstrated. The lack of medical physicists is one of the important challenges.

PAEDIATRIC NECK MULTIDETECTOR COMPUTED TOMOGRAPHY: THE EFFECT OF BISMUTH SHIELDING ON THYROID DOSE AND IMAGE QUALITY

This study investigated the effect of bismuth shielding on thyroid dose and image quality in paediatric neck multidetector computed tomography (MDCT) performed with fixed tube current (FTC) and automatic exposure control (AEC). Four paediatric anthropomorphic phantoms representing the equivalent newborn, 1-, 5- and 10-y-old child were subjected to neck CT using a 16-slice MDCT system. Each scan was performed without and with single- and double-layered bismuth shield placed on the skin surface above the thyroid. Scans were repeated with cotton spacers of 1, 2 and 3 cm thick placed between the skin and shield, to study the effect of skin-to-shielding distance on image noise. Thyroid dose was measured with thermoluminescent dosemeters. The location of the thyroid within the phantom slices was determined by anthropometric data from patients' CT examinations whose body stature closely matched the phantoms. Effective dose (E) was estimated using the dose-length product (DLP) method. Image quality of resulted CT images was assessed through the image noise. Activation of AEC was found to decrease the thyroid dose by 46 % to the 10-y-old phantom subjected to neck CT. When FTC technique is used, single- and double-layered bismuth shielding was found to reduce the thyroid dose to the same phantom by 35 and 47 %, respectively. The corresponding reductions in AEC-activated scans were 60 and 66 %, respectively. Elevation of shields by 1-, 2- and 3-cm cotton spacers decreased the image noise by 69, 87 and 92 %, respectively, for single-layered FTC, without considerably affecting the thyroid dose. AEC was more effective in thyroid dose reduction than in-plane bismuth shields. Application of cotton spacers had no significant impact on thyroid dose, but significantly decreased the image noise.

Patterns and trends of computed tomography usage in outpatients of the Brazilian public healthcare system, 2001-2011

While the patterns and trends of computed tomography (CT) are well documented in developed countries, relatively little is known about CT usage in developing countries, including Brazil. We evaluated CT usage among outpatients from the public healthcare system in Brazil (SUS), which is the unique healthcare provider to about 75% of the Brazilian population. We collected the annual number of CT procedures and type of CT examinations performed in SUS for the period 2001-2011. Age at examination was evaluated for 2008-2011. CT usage in Brazil has more than tripled during the study period, but the most striking annual increase (17.5%) was observed over the years 2008-2011. Head was the most frequently examined region for all age groups, but a decreasing trend of proportional contribution of head CT, with a simultaneous increase of abdomen/pelvis and chest CT over time was observed. CT examination for pediatric and young adult patients was about 13% of all CTs (9% if we considered age-standardized CT rates). CT usage has grown rapidly in Brazil and may still be increasing. Increased CT usage may certainly be associated with improved patient care. However, given the high frequency of pediatric and young adult CT procedures and the suggested associated cancer risk, efforts need to be undertaken to reduce unwarranted CT scans in Brazil.

National diagnostic reference level initiative for computed tomography examinations in Kenya

The purpose of this study was to estimate the computed tomography (CT) examination frequency, patient radiation exposure, effective doses and national diagnostic reference levels (NDRLs) associated with CT examinations in clinical practice. A structured questionnaire-type form was developed for recording examination frequency, scanning protocols and patient radiation exposure during CT procedures in fully equipped medical facilities across the country. The national annual number of CT examinations per 1000 people was estimated to be 3 procedures. The volume-weighted CT dose index, dose length product, effective dose and NDRLs were determined for 20 types of adult and paediatric CT examinations. Additionally, the CT annual collective effective dose and effective dose per capita were approximated. The radiation exposure during CT examinations was broadly distributed between the facilities that took part in the study. This calls for a need to develop and implement diagnostic reference levels as a standardisation and optimisation tool for the radiological protection of patients at all the CT facilities nationwide.

Paediatric doses during some common X-ray procedures at selected referral hospitals in Tanzania

The aim of this study was to determine the radiation doses to paediatric patients of different age groups at three large hospitals for optimisation purposes. The entrance surface air kerma (ESAK) values were determined from the measured X-ray output values using calibrated ionisation chamber, TW 233612 and clinical patient parameters. The air kerma-area product (KAP) values were measured using a calibrated Diamentor E2 system. The volume computed tomography dose index (CTDIvol) and dose length product (DLP) values were obtained from the computed tomography (CT) equipment verified by a calibrated CT chamber, Unifors Xi CT. Irrespective of age groups, the results show that the median ESAK values ranged from 62.6 to 248.1 µGy. The median KAP values ranged from 135.6 to 1612 µGy cm(2), while the median DLP values ranged from 119.1 to 600 mGy cm. Analysis of the results indicates that optimisation can be achieved through good practice awareness and patient dose and image quality evaluations.

Establishment of diagnostic reference levels in computed tomography for paediatric patients in Sudan: a pilot study

Paediatric patients are recognised to be at higher risk of developing radiation-induced cancer than adults. The purpose of this pilot study was to evaluate the radiation doses to paediatric patients during computed tomography (CT) procedures in order to propose local diagnostic reference levels (DRLs). A total of 296 patients (aged 6-10 y) were investigated in 8 hospitals equipped with 64-, 16- and dual-slice CT machines. The mean dose length product values were 772, 446 and 178 mGy cm for head, abdomen and chest, respectively. Imaging protocols were not adapted to the patient's weight in certain CT machines. The results confirmed that paediatric patients are exposed to an unnecessary radiation dose. The established DRLs were higher than those available in other countries. This study showed the need for harmonisation of the practice in CT departments and radiation dose optimisation.

A study to establish international diagnostic reference levels for paediatric computed tomography

The article reports results from the largest international dose survey in paediatric computed tomography (CT) in 32 countries and proposes international diagnostic reference levels (DRLs) in terms of computed tomography dose index (CTDI vol) and dose length product (DLP). It also assesses whether mean or median values of individual facilities should be used. A total of 6115 individual patient data were recorded among four age groups: <1 y, >1-5 y, >5-10 y and >10-15 y. CTDIw, CTDI vol and DLP from the CT console were recorded in dedicated forms together with patient data and technical parameters. Statistical analysis was performed, and international DRLs were established at rounded 75th percentile values of distribution of median values from all CT facilities. The study presents evidence in favour of using median rather than mean of patient dose indices as the representative of typical local dose in a facility, and for establishing DRLs as third quartile of median values. International DRLs were established for paediatric CT examinations for routine head, chest and abdomen in the four age groups. DRLs for CTDI vol are similar to the reference values from other published reports, with some differences for chest and abdomen CT. Higher variations were observed between DLP values, based on a survey of whole multi-phase exams. It may be noted that other studies in literature were based on single phase only. DRLs reported in this article can be used in countries without sufficient medical physics support to identify non-optimised practice. Recommendations to improve the accuracy and importance of future surveys are provided.

Patient grouping for dose surveys and establishment of diagnostic reference levels in paediatric computed tomography

There has been confusion in literature on whether paediatric patients should be grouped according to age, weight or other parameters when dealing with dose surveys. The present work aims to suggest a pragmatic approach to achieve reasonable accuracy for performing patient dose surveys in countries with limited resources. The analysis is based on a subset of data collected within the IAEA survey of paediatric computed tomography (CT) doses, involving 82 CT facilities from 32 countries in Asia, Europe, Africa and Latin America. Data for 6115 patients were collected, in 34.5 % of which data for weight were available. The present study suggests that using four age groups, <1, >1-5, >5-10 and >10-15 y, is realistic and pragmatic for dose surveys in less resourced countries and for the establishment of DRLs. To ensure relevant accuracy of results, data for >30 patients in a particular age group should be collected if patient weight is not known. If a smaller sample is used, patient weight should be recorded and the median weight in the sample should be within 5-10 % from the median weight of the sample for which the DRLs were established. Comparison of results from different surveys should always be performed with caution, taking into consideration the way of grouping of paediatric patients. Dose results can be corrected for differences in patient weight/age group.

Justification of CT scans using referral guidelines for imaging

This study analyses the efficiency of the justification of individual computed tomography (CT) procedures using the good practice guide. The conformity of the CT scans with guide's recommendations was retrospectively analysed in a paediatric emergency hospital in Romania. The involved patient doses were estimated. The results show that around one-third of the examinations were not prescribed in conformity with the guide's recommendations, but these results are affected by unclear guide provisions, discussed here. The implications of the provisions of the revised International Atomic Energy Agency's Basic Safety Standards and of the Council Directive 2013/59/EURATOM were analysed. The education and training courses for medical doctors disseminating the provisions of the good practice guide should be considered as the main support for the justification of the CT scans at the individual level.

Exposure of the French paediatric population to ionising radiation from diagnostic medical procedures in 2010

BACKGROUND

Medical examination is the main source of artificial radiation exposure. Because children present an increased sensitivity to ionising radiation, radiology practices at a national level in paediatrics should be monitored.

OBJECTIVE

This study describes the ionising radiation exposure from diagnostic medical examinations of the French paediatric population in 2010.

MATERIALS AND METHODS

Data on frequency of examinations were provided by the French National Health Insurance through a representative sample including 107,627 children ages 0-15 years. Effective doses for each type of procedure were obtained from the published French literature. Median and mean effective doses were calculated for the studied population.

RESULTS

About a third of the children were exposed to at least one examination using ionising radiation in 2010. Conventional radiology, dental exams, CT scans and nuclear medicine and interventional radiology represent respectively 55.3%, 42.3%, 2.1% and 0.3% of the procedures. Children 10-15 years old and babies from birth to 1 year are the most exposed populations, with respectively 1,098 and 734 examinations per 1,000 children per year. Before 1 year of age, chest and pelvis radiographs are the most common imaging tests, 54% and 32%, respectively. Only 1% of the studied population is exposed to CT scan, with 62% of these children exposed to a head-and-neck procedure. The annual median and mean effective doses were respectively 0.03 mSv and 0.7 mSv for the exposed children.

CONCLUSION

This study gives updated reference data on French paediatric exposure to medical ionising radiation that can be used for public health or epidemiological purposes. Paediatric diagnostic use appears much lower than that of the whole French population as estimated in a previous study.

Multi-national findings on radiation protection of children

This article reviews issues of radiation protection in children in 52 low-resource countries. Extensive information was obtained through a survey by the International Atomic Energy Agency (IAEA); wide-ranging information was available from 40 countries and data from the other countries pertained to frequency of pediatric CT examinations. Of note is that multi-detector CT (MDCT) was available in 77% of responses to the survey, typically nodal centers in these countries. Nearly 75% of these scanners were reported to have dose displays. The pediatric CT usage was lower in European facilities as compared to Asian and African facilities, where usage was twice as high. The most frequently scanned body part was the head. Frequent use of 120 kVp was reported in children. The ratio of maximum to minimum CT dose index volume (CTDIvol) values varied between 15 for abdomen CT in the age group 5-10 years and 100 for chest CT in the age group <1 year. In 8% of the CT systems, CTDI values for pediatric patients were higher than those for adults in at least one age group and for one type of examination. Use of adult protocols for children was associated with CTDIw or CTDIvol values in children that were double those of adults for head and chest examination and 50% higher for abdomen examination. Patient dose records were kept in nearly half of the facilities, with the highest frequency in Europe (55% of participating facilities), and in 49% of Asian, 36% of Latin American and 14% of African facilities. The analysis of the first-choice examinations in seven clinical conditions showed that practice was in accordance with guidelines for only three of seven specified clinical conditions.

CT imaging in a large part of the world: what we know and what we can learn

This paper describes how cooperation among international organizations, as modeled in Europe, can work to improve imaging safety and standards for children throughout the world. This is demonstrated in the mechanisms employed in a large-scale multi-national study on CT imaging safety practices described elsewhere in this issue of Pediatric Radiology. Here we learn approaches through which CT safety standards have been achieved and the international resources available to help in standardizing safety practices in medical imaging. There are unique strengths of the approach in Europe, which has mandatory requirements on member states to facilitate strengthening of radiation protection. Most countries have national regulatory mechanisms for radiation protection in medicine. International organizations play a significant role in supporting projects in lower-resource countries such that a large proportion of radiologic professionals in low-resource countries are trained through assistance by these organizations. Many of these international organizations make it possible for professionals worldwide to download free training material. Collaboration among international organizations and the Image Gently campaign toward consensus with regard to radiation protection can go further than individual opinions in promoting a higher standard of radiation protection around the world.

Frequency and collective dose of medical procedures in Kenya

The first comprehensive national survey on frequency and radiation dose imparted to the population from radiological procedures was carried out in Kenya and reported here. This survey involved assessment of frequency, typical patient radiation exposure, and collective effective dose from general radiography, fluoroscopy, interventional procedures (IPs), mammography, and computed tomography. About 300 x-ray facilities across the country were invited to participate in the survey, and a 31% response was recorded. The individual and collective radiation burdens of more than 62 types of pediatric and adult radiological examinations were quantified using effective and collective dose. The average effective dose for each radiological examination was assessed from the x-ray efficiency performance tests and patient data from over 30 representative radiological facilities. The results found indicated that over 3 million x-ray procedures were performed in 2011, resulting in an annual collective effective dose of 2,157 person-Sv and an annual effective dose per capita of 0.05 mSv. The most frequent examinations were general radiography (94%), computed tomography (3.3%), and fluoroscopy (2.5%). Although the contribution of computed tomography was small in terms of frequency, this procedure accounted for 36% of the effective dose per capita. General radiography was the most frequent type of examination with a contribution of 55% of the effective dose per capita.

Justification of CT examinations in young adults and children can be improved by education, guideline implementation and increased MRI capacity

OBJECTIVE

To determine whether the justification of CT examinations performed on young patients can be improved by various interventions and whether these have an effect on the total number of CTs performed.

METHODS

Specific interventions-education, guideline implementation and increased MRI capacity-were introduced at the Oulu University Hospital, Oulu, Finland, following a previous study demonstrating unjustified use of CT examination in young patients. In the present study, the justification of 177 CT examinations of the lumbar and cervical spine, head, abdomen, nasal sinuses and trauma performed on patients aged under 35 years in 2009 was analysed retrospectively by looking at requests and corresponding patient files. The indications of the examinations were compared with the referral guidelines recommended by the European Commission. Results from our previously published similar study carried out before the interventions were used as a reference.

RESULTS

The proportion of justified CT examinations increased from 71% (141/200) in 2005 to 87% (154/177) in 2009 (p<0.001), and in the lumbar spine group from 23% (7/30) to 81% (22/27) (p<0.001). In the case of most of the unjustified examinations, MRI could have been performed instead. The total number of CT examinations carried out on young patients decreased by 7% (p=0.012) and in the lumbar spine group by 79% (p<0.001).

CONCLUSION

The implemented interventions decreased the number of CT examinations performed on young patients, and the justification of the examinations improved significantly.

ADVANCES IN KNOWLEDGE

This study demonstrates that it is possible to reduce the number of various CT examinations and to improve their justification in young patients by regular education, guideline implementation and increased MRI capacity.

ICRP and IAEA actions on radiation protection in computed tomography

In 1998, the International Commission on Radiological Protection (ICRP) warned that computed tomography (CT) doses were high, and the frequency of usage was likely to increase in view of spiral CT technology that enhances patient convenience and provides high-quality diagnostic information. Two ICRP publications (Publications 87 and 102) have provided patient dose management recommendations while reviewing the technology and results of optimisations to date, and stimulated interest in patient dose management. The International Atomic Energy Agency, on the other hand, has been instrumental in assessing the state of practice at grassroots level, identifying lacunae in justification and optimisation, providing guidance to counterparts in various countries, and improving practice. The results from approximately 50 less-resourced countries for adult and paediatric CT studies have become available, and some have been published. The concerted efforts and actions by these two international organisations have contributed to better awareness and improvement of patient protection in CT in adults and children in many countries.

IAEA survey of paediatric computed tomography practice in 40 countries in Asia, Europe, Latin America and Africa: procedures and protocols

OBJECTIVE

To survey procedures and protocols in paediatric computed tomography (CT) in 40 less resourced countries.

METHODS

Under a project of the International Atomic Energy Agency, 146 CT facilities in 40 countries of Africa, Asia, Europe and Latin America responded to an electronic survey of CT technology, exposure parameters, CT protocols and doses.

RESULTS

Modern MDCT systems are available in 77 % of the facilities surveyed with dedicated paediatric CT protocols available in 94 %. However, protocols for some age groups were unavailable in around 50 % of the facilities surveyed. Indication-based protocols were used in 57 % of facilities. Estimates of radiation dose using CTDI or DLP from standard CT protocols demonstrated wide variation up to a factor of 100. CTDI(vol) values for the head and chest were between two and five times those for an adult at some sites. Sedation and use of shielding were frequently reported; immobilisation was not. Records of exposure factors were kept at 49 % of sites.

CONCLUSION

There is significant potential for improvement in CT practice and protocol use for children in less resourced countries. Dose estimates for young children varied widely. This survey provides critical baseline data for ongoing quality improvement efforts by the IAEA.