Pediatric Head CT Research Articles

Investigating the Effects of Tube Current and Tube Voltage on Patient Dose in Computed Tomography Examinations with Principial Component Analysis and Cluster Analysis: Phantom Study.

The aim of this study was to investigate the effects of tube current and tube voltage choices on patient dose in adult and pediatric CT protocols by qualitative analysis using Principal Component Analysis (PCA), cluster analysis, and statistical analysis.Dose length product (DLP), Effective mAs (Eff. mAs), and volume-weighted CT dose index (CTDIvol) dose descriptors were obtained from 16 adult and pediatric head phantom CT examinations. Different tube voltage and tube current values were selected in both pediatric head and adult head CT imaging protocols, and PCA and cluster analysis were applied to the data obtained for qualitative analysis of the relationship between CTDIvol, Eff. mAs and Total DLP values. The two principial components (PC) with the highest values among those obtained as a result of the PCA method were used. PC1 was 70.97%, and PC2 was 28.03%. In the cluster analysis, it was observed that the values obtained from pediatric and adult phantom CT scans were classified into two different clusters. The correlation coefficient for adult patients was r = 0.998, and for pediatric patients, the correlation coefficient was r = 0.947. When the obtained clusters were examined, the degree of closeness or distance of the variables could be observed. In the study, as a result of the analysis of CTDIvol, Eff. mAs and Total DLP data based on manufacturer data at different kV and mA values with PCA and cluster analysis, it was shown that pediatric patients could be exposed to more radiation than the adult patients.

Beyond the AJR: Deep Learning Shows Promise in the Detection of Retinal Hemorrhage on Pediatric Head CT.

Beyond the AJR: Deep Learning Shows Promise in the Detection of Retinal Hemorrhage on Pediatric Head CT.

Quantitative Analysis of the Clinical Reasons Influencing the Frequency of Pediatric Head CT Examinations: A Single-Center Observation Study.

Epidemiological studies on radiation exposure from pediatric CT scans have attracted attention in terms of radiological protection. These studies have not taken into account the reasons why CT examinations were performed. It is presumed that there are clinical reasons that justify more frequent CT examinations in children. The purpose of this study was to characterize the clinical reasons why relatively high numbers of head CT examinations (NHCT) are frequently performed and to conduct a statistical analysis to determine the factors governing the NHCT. Patient information, the date of examination, and medical conditions for examination data stored on the radiology information system were used to investigate the reasons for undergoing CT examinations. The target facility was National Children's Hospital; data were obtained from March 2002 to April 2017, and the age of the study population was less than 16 years old. Quantitative analysis of the factors associated with frequent examinations was conducted by Poisson regression analysis. Among all patients who had a CT scan, 76.6% had head CT examinations, and 43.4% of children were under 1 year old at the time of the initial examination. There were marked differences in the number of examinations depending on the disease. The average NHCT was higher for children younger than 5 days of age. Among children less than 1 year of age with surgery, there was a marked difference between hydrocephalus, with a mean = 15.5 (95% CI 14.3,16.8), and trauma, with a mean = 8.3 (95% CI 7.2,9.4). In conclusion, this study revealed that NHCT was significantly higher in children who had undergone surgery than in those who had not been to the hospital. The clinical reasons behind patients with higher NHCT should be considered in investigating a causal relationship between CT exposure and brain tumors.

Monitoring Pediatric Head CT Scan Dose Levels: A Retrospective Study of Diagnostic Reference Levels in a Single Hospital in Abu Dhabi, UAE

Diagnostic reference levels (DRLs) are critical operational standards for monitoring radiological imaging parameters and ensuring patient safety in hospitals. A regular review of DRLs is necessary to optimize scanners and protocol parameters. This retrospective study collected data on the CT dose index volume and dose–length product for 250 children who underwent head CT scans in the region of Abu Dhabi, United Arab Emirates. Descriptive statistics were used to present median, range, and interquartile range values for each pediatric age group, based on region and protocol. The 75th percentile was used as the reference point for local DRLs. Proposed values of DRLs were suggested per age groups; 304 mGy∙cm (children < 1 year), 385 mGy∙cm (children ≥ 1 year to <5 years), 441 mGy∙cm (children ≥ 5 years to <10 years), and 568 mGy∙cm (patients ≥ 10 years to <16 years. A comparison of the local DRLs with previously established ones was carried out, and differences were discussed. To the best of our knowledge, this is the first study on pediatric head CT scans in this region. We believe the results can be used as a baseline for establishing local DRLs in the Emirate of Abu Dhabi and national DRLs in the United Arab Emirates.

New evidence for brain cancer risk after a single paediatric CT scan

Despite the unquestionable benefits of diagnostic radiation exposure, the potential health risks are of considerable concern, particularly for the risk of brain cancer following paediatric head CT examinations. In The Lancet Oncology, Michael Hauptmann and colleagues1 present the results of a large-scale study from nine European countries (the EPI-CT cohort study) to quantify the risks of brain cancer in more than 650 000 patients who had a first head or neck CT examination when they were younger than 22 years.

Size-specific dose estimates for pediatric head CT protocols based on the AAPM report TG-293

PurposeTo establish the Size Specific Dose Estimate (SSDE) typical values for pediatric head CT examinations based on the AAPM report TG-293; to provide a new stratification based on the water-equivalent diameter (Dw), given that SSDE is related to the head size. Methods296 Head CT scans of pediatric patients collected using a dose monitoring software were retrospectively analysed. Typical values were derived stratifying data by age in three methods: the first proposed by the European Guidelines on Diagnostic Reference Levels for Pediatric Imaging (RP185), the second by the National Istisan Report 20/22 and a local one related to the clinical protocols (LStrata). For each scan, a self-developed Matlab routine calculated the water-equivalent diameter (Dw) and related SSDE values with the conversion factors fH16and fB16provided by the AAPM reports TG-293 and TG-204, respectively. Eventually, a Dwstratification was introduced starting from a measure of the lateral dimension of the head. ResultsSSDE based on TG-204 overestimatesthe dose up to 12%. Four Dwgroups were identified thanks to the good correlation between the head lateral dimension andDw: Dw < 14 cm, 14 ≤ Dw < 16 cm, 16 ≤ Dw< 17 cm, Dw≥ 17 cm. The Dw-stratified dosimetric indices presentgreater variability than those grouped by age because of the large variability of the size of the infant's head. ConclusionsThe variability of the SSDE metric underlines that age-optimized protocols are not when size is considered.

Adaptation of Deep Learning Image Reconstruction for Pediatric Head CT: A Focus on the Image Quality.

To assess the effect of deep learning image reconstruction (DLIR) for head CT in pediatric patients. We collected 126 pediatric head CT images, which were reconstructed using filtered back projection, iterative reconstruction using adaptive statistical iterative reconstruction (ASiR)-V, and all three levels of DLIR (TrueFidelity; GE Healthcare). Each image set group was divided into four subgroups according to the patients' ages. Clinical and dose-related data were reviewed. Quantitative parameters, including the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), and qualitative parameters, including noise, gray matter-white matter (GM-WM) differentiation, sharpness, artifact, acceptability, and unfamiliar texture change were evaluated and compared. The SNR and CNR of each level in each age group increased among strength levels of DLIR. High-level DLIR showed a significantly improved SNR and CNR (p < 0.05). Sequential reduction of noise, improvement of GM-WM differentiation, and improvement of sharpness was noted among strength levels of DLIR. Those of high-level DLIR showed a similar value as that with ASiR-V. Artifact and acceptability did not show a significant difference among the adapted levels of DLIR. Adaptation of high-level DLIR for the pediatric head CT can significantly reduce image noise. Modification is needed while processing artifacts.

OD100 - Strategy for paediatric head CT exposure optimization: protocols and workflows

OD100 - Strategy for paediatric head CT exposure optimization: protocols and workflows

Application of a deep learning image reconstruction (DLIR) algorithm in head CT imaging for children to improve image quality and lesion detection

BackgroundTo evaluate the performance of a Deep Learning Image Reconstruction (DLIR) algorithm in pediatric head CT for improving image quality and lesion detection with 0.625 mm thin-slice images.MethodsLow-dose axial head CT scans of 50 children with 120 kV, 0.8 s rotation and age-dependent 150–220 mA tube current were selected. Images were reconstructed at 5 mm and 0.625 mm slice thickness using Filtered back projection (FBP), Adaptive statistical iterative reconstruction-v at 50% strength (50%ASIR-V) (as reference standard), 100%ASIR-V and DLIR-high (DL-H). The CT attenuation and standard deviation values of the gray and white matters in the basal ganglia were measured. The clarity of sulci/cisterns, boundary between white and gray matters, and overall image quality was subjectively evaluated. The number of lesions in each reconstruction group was counted.ResultsThe 5 mm FBP, 50%ASIR-V, 100%ASIR-V and DL-H images had a subjective score of 2.25 ± 0.44, 3.05 ± 0.23, 2.87 ± 0.39 and 3.64 ± 0.49 in a 5-point scale, respectively with DL-H having the lowest image noise of white matter at 2.00 ± 0.34 HU; For the 0.625 mm images, only DL-H images met the diagnostic requirement. The 0.625 mm DL-H images had similar image noise (3.11 ± 0.58 HU) of the white matter and overall image quality score (3.04 ± 0.33) as the 5 mm 50% ASIR-V images (3.16 ± 0.60 HU and 3.05 ± 0.23). Sixty-five lesions were recognized in 5 mm 50%ASIR-V images and 69 were detected in 0.625 mm DL-H images.ConclusionDL-H improves the head CT image quality for children compared with ASIR-V images. The 0.625 mm DL-H images improve lesion detection and produce similar image noise as the 5 mm 50%ASIR-V images, indicating a potential 85% dose reduction if current image quality and slice thickness are desired.

SIZE-SPECIFIC DOSE ESTIMATES FOR PEDIATRIC NON-CONTRAST HEAD CT SCANS: A RETROSPECTIVE PATIENT STUDY IN TUNJA, COLOMBIA.

This investigation is aimed to study the feasibility of size-specific dose estimate (SSDE) to patient dosimetry in pediatric head CT scans and to establish typical values in a hospital in Tunja, Colombia. The volumetric computed tomography index (CTDIvol) and the dose-length product of 468 pediatric patients from newborn to 15-year-olds, who underwent non-contrast head CT scans, were collected retrospectively. For 186 cases only, SSDE was estimated using patient attenuated-based size metrics and CTDIvol,16-to-SSDE conversion factors reported in AAPM report 293. Results showed that SSDE is an accurate metric that can be used to establish typical dose values from pediatric head CT scans. Median SSDE values of 33.5, 31.6, 36.2 and 57.9mGy were established as typical dose values for the 0-<3months, 3months-<1 y, 1-<6 y and≥6 y, respectively, to further assist the optimization process at the hospital. Further studies with more robust data of patients and hospitals should be conducted to establish local and national dose reference levels from pediatric CT scans in Colombia.

Pediatric Head CT: Automated Quantitative Analysis with Quantile Regression.

Together with quantile regression methods, such a model would have the potential for clinical utility through automated quantitative comparison of individual cases relative to their age and gender-matched peer group. Our aim was to demonstrate the automated processing of digital clinical head CT data in the development of a clinically useful model of age-related changes of the brain in the first 2 decades of life. A total of 415 (209 female) consecutive, clinical head CTs with radiographically normal findings from patients from birth through 20 years of age were retrospectively selected and subjected to automated segmentation. Brain volume, brain parenchymal fraction, brain radiodensity, and brain radiomass were assessed as a function of patient age. Statistical modeling and quantile regression were performed. Brain volume increased from 400 cm3 at birth to 1350 cm3 at 20 years of age (>3-fold). Males had a slightly steeper growth trajectory than females, with approximately 8% difference in volume between the sexes established in the first few years of life. Brain parenchymal fraction was variable at younger than 2 years of age, stabilizing between 0.85 and 0.92 at 2-3 years of age. Brain mean radiodensity was lower at birth (24 HU) and increased through 3 years of age, after which it stabilized near 30 HU, an approximately 25% increase. The product of brain volume and mean brain radiodensity (radiomass), increased from 700 HU × mL at birth to 3900 HU × mL, a 5.6-fold increase, with approximately 5% difference between males and females at 20 years. Quantile regression enables a given metric to be interpreted relative to an age- and sex-matched peer group. Automated segmentation of clinical head CT images permitted the generation of a reference database for quantitative analysis of pediatric and adolescent brains. Quantile regression facilitates clinical application.

소아 두부 CT에서 의료방사선 피폭선량 평가

소아 두부 CT에서 의료방사선 피폭선량 평가

268 Comparing Pediatric Head CT Rules Using Outcomes for Acute Lifesaving Intervention

Rates of pediatric head CT for mild blunt head trauma (BHT) have not shown improvement while published clinical prediction rules (CDRs) have been available. Outcomes for these CDRs may be too inclusive and set the threshold to scan unreasonably low. We sought to compare the sensitivity of five published CDRs in detecting outcomes limited to the need for acute lifesaving intervention. We conducted a retrospective chart review of patients <18 years old presenting to the ED between the years 2006 through 2013 at a single academic Level 1 Pediatric Trauma Center with diagnoses consistent with intracranial injury and who received head CT as part of their management. Patients meeting criteria for mild non-penetrating BHT (GCS 14-15) were screened for the following outcomes indicating a need for acute lifesaving intervention: neurosurgical procedure, intubation due to head injury, and death. The five following CDRs were then assessed for their ability to detect patients with these outcomes: the Pediatric Emergency Care Applied Research Network (PECARN) CT head rule, the Canadian Assessment of Tomography for Childhood Head injury 2 (CATCH2) rule, the Children’s Head injury ALgorithm for prediction of Clinically Important Events (CHALICE), the Pediatric National Emergency X-Radiography Utilization Study II (NEXUS II) Head CT Decision Instrument, and the decision rule developed by Palchak et al. Out of 1,810 patients with diagnosis codes consistent with intracranial injury and that received CT, 1,162 met the criteria for mild non-penetrating BHT and were screened for the outcomes of interest. 21 patients had one or more of the three outcomes, representing 1.8% of those screened. The average age was 4.6 years and the majority (62%) were male. All 21 patients required intubation due to their head injury with 9 receiving a neurosurgical procedure (0.8%) and no deaths. All CDRs displayed 100% sensitivity with each patient meeting at least 1 criterion for each CDR. All CDRs displayed 100% sensitivity at detecting outcomes indicating a need for acute lifesaving intervention in pediatric mild BHT. Future prospective studies should consider similar outcomes to assess their utility in decreasing unnecessary pediatric head CT.

Value of using adaptive statistical iterative reconstruction-V (ASIR-V) technology in pediatric head CT dose reduction

BackgroundWith widespread use of pediatric head CT, it is critically important to protect patients from radiation hazards, using reduced dose CT techniques. In this regard, adaptive statistical iterative reconstruction-V (ASIR-V) algorithm can decrease image noise, generating CT images of reasonable diagnostic quality with less radiation. The objective of this study was radiation dose assessment, quantitative and qualitative evaluation of reduced dose pediatric head CT using ASIR-V 60% and 80% reconstruction.ResultsRetrospective analysis was performed on two groups of pediatric head CT examinations, a reduced dose CT examination group with ASIR-V reconstruction (ASIR group) (n = 27) and a standard dose CT examination group without ASIR reconstruction (non-ASIR group) (n = 14). The average effective dose (ED) of ASIR group was significantly lower than that of the non-ASIR group (1.04 ± 0.1 mS vs 3.48 ± 0.45 mS; p = 0.001). Quantitative analysis revealed comparable results of signal to noise ratio (SNR) and contrast to noise ratio (CNR) of ASIR and non-ASIR groups (p > 0.05). Qualitative evaluation of resulting images by two readers revealed comparable results of both ASIR and non-ASIR groups (p > 0.05) with excellent inter-reader agreement (κ = 0.97). Both quantitative and qualitative assessment demonstrated better ASIR-V 80% than ASIR-V 60% reconstructed images.ConclusionASIR-V algorithm is a promising technology for effective dose reduction of pediatric head CT with preservation of diagnostic image quality.

Relation between age and CT radiation doses: Dose trends in 705 pediatric head CT

PurposeTo evaluate the relationship between patient age and radiation doses associated with routine pediatric head CT performed with automatic tube potential selection and tube current modulation techniques. MethodsWe obtained patient demographics, scan parameters, and radiation dose descriptors (CT dose index volume -CTDIvol and dose length product -DLP) associated with consecutive routine head CT in 705 children (mean age 6.9 ± 5 years). Children were scanned on one of the three multidetector-row CTs (64–128 slices, Siemens) over 6 months period in a tertiary hospital. All head CT exams were performed in helical scan mode using automatic tube potential selection (Care kV) and automatic tube current modulation (Care Dose 4D) techniques. The information was obtained from a radiation dose monitoring software. Data were analyzed using linear correlation and analysis of variance. ResultsMost age-wise median CTDIvol (9−27 mGy; 703/705 pediatric head CT, >99 %) from our institution were lower than the European Diagnostic Reference Levels (EDRL, CTDIvol 24−50 mGy) but median DLP (151−586 mGy cm) from 201/705 children (28 %) was higher than the EDRL (DLP 300−650 mGy cm). Unlike the age-stratified EDRL, a combination of automatic tube potential selection and tube current modulation for pediatric head results in a significant linear correlation between radiation doses and patient age (r2 = 0.66, p < 0.001). ConclusionsRadiation doses for head CT change linearly with children's age. Despite lower CTDIvol and DLP for most children, longer scan length resulted in higher DLP for some pediatric head CT compared to the corresponding EDRL; this result underscores the need to promote clear guidelines for technologists operating CT.

Pengaruh Parameter Milliampere-Second (mAs) terhadap Kualitas Citra Dan Dosis Radiasi Pada Pemeriksaan CT scan Kepala Pediatrik

Radiographers are responsible for administering radiation doses according to the principle of As Low As Reasonably Achievable (ALARA), to optimize the use of CT parameters to produce good image quality by minimizing radiation doses. The purpose of this study was to determine the effect of mAs parameters on image quality and radiation dose received by pediatric CT head examination patients. The research method to perform image processing results of examination using radiant viewer and analysis of value Contrast to noise ratio (CNR) as a parameter of image quality and CTDIvol to determine the estimated radiation dose, then an analysis is performed to determine whether there is an influence of mAs on the CNR and CTDIvol values. The mean value of kV 116 ± 8.28, the mean value of parameter mAs 161.5 ± 63.46, the mean SNR parameter value is 7.5 ± 0.8, the mean return value of CNR parameter was 0.318 ± 0.291, the mean value of the CTDIvol parameter is 18.68 mGy ± 4.55 mGy, the average value of DLP parameters was 408.7 mGy x cm ± 105.2 mGy x cm, the mean value of parameter DLP is 441.2 mGy x cm ± 155.2 mGy x cm. With linear regression analysis of test results between mAs to CNR is R2 = 0.045. then to the results of linear regression between mAs against CTDI is R2 = 0704, the estimated radiation dose limit for the average value of CTDIvol 18.68 mGy and the average value of DLP 408.7 mGy x cm, this means the protocol CT scan of the head of the pediatric use is still within safe limits by Diagnostic Reference Level of BAPETEN in 2018 to pediatric head CT examination

Dose optimisation in paediatric CT examination: Assessment on current scanning protocols associated with radiation dose

Request for paediatric CT imaging has been increasing recently, and thus assessment of current paediatric CT protocols is of crucial importance as to assess the associated potential risk and possibly identify the need to modify the current practice. The aim of this study was to optimize the current local practice through investigation on the radiation dose distribution and existing routine scanning protocols of paediatric head and abdomen CT examinations at Radiology Department, HUSM, Kelantan, Malaysia. A total of 250 paediatric (age between 0‒12 years) CT examinations (134 of head CT and 116 of abdomen CT scans) were retrospectively collected from PACS and further analysed. The dose metrics in volume CT dose index (CTDIvol) and dose length product (DLP) with combination of exposure parameters (kV, mAs, pitch, scan length and acquisition time) for paediatric CT imaging were evaluated. Third quartile values of local dose distribution were then compared with selected international DRLs. The third quartile values for CTDIvol (mGy) and DLP (mGy.cm) for head and abdomen CT scans with respect to the age groups were 0–3 years (32/557 and 7/232), 4–6 years (61/1105 and 9/251), 7–9 years (117/1454 and 11/405), 10–12years (117/2203 and 14/566) respectively. From the comparative study, the local dose received from paediatric head CT scans were higher than the recommended levels. This is mainly due to selection of scanning parameters which were higher than the optimised paediatric protocols. Tube voltage selection was ranged from 100‒120 kV for all age groups except the head CT scan in group 4 that used a constant 120 kV. Applied mAs varied in the ranges from 100‒410 mAs for head CT scan and 35–100 mAs for abdominal CT scans and increases as the paediatric age increased. From the findings, review and optimisation on the current scanning protocols is required especially for head CT scan to complement the corresponding age groups and sizes while maintaining the diagnostic values.

Correlation between age and head diameters in the paediatric patients during CT examination of the head

Abstract An estimate of patient dose, patient size should be used to normalise the output dose of CT machine in the terms of volume CT dose index, CTDIvol. There are two metrics to characterise the patient size, i.e. the effective diameter (Deff) and the water-equivalent diameter (Dw). These two metrics could be estimated by patient age. However, to date, relationships between the age and head patient size (Deff and Dw) have not been established for the pediatric patients. The aim of this study was to establish the relationships between the age and head patient size (Deff and the Dw) as the basis for calculating the size-specific dose estimate (SSDE) for paediatric head CT examination. The data were retrospectively collected from serial images of the CT head in the DICOM file from one hundred and thirteen paediatric patients aged 0-17 years (63 male and 50 female patients) underwent head CT examinations. The patient’s sizes (Deff and Dw) were calculated from the patient’s images using the IndoseCT version 15a software. The Deff and Dw values were correlated with age of patients using regression analysis. It was found that patient size (Deff and Dw) correlated well with the age of the patient with R2 more than 0.8. The size of the Dw is bigger than the Deff. The Deff values for male patients are 12.38 to 16.21 cm, and Dw values are 11.96 to 18.16 cm, respectively. For female patients, the values of Deff are from 11.54 to 16.87 cm, and the values of Dw are from 11.60 to 17.86 cm, respectively.

How patient off-centering impacts organ dose and image noise in pediatric head and thoracoabdominal CT.

To assess the impact of patient off-centering on organ dose and image noise for head and thoracoabdominal CT in a pediatric phantom. An anthropomorphic phantom simulating a 5-year-old child was used. Semiconductor dosimeters were placed in various cranial and thoracoabdominal organs. Head and thoracoabdominal CT were performed using automatic tube current modulation (ATCM) and default bowtie filters. The phantom was imaged repeatedly at vertical table positions ranging from - 6 to + 6cm from the 0-position. Tube current time products (TCTP), organ doses, and image noise were recorded. Scatter radiation was measured in the thyroid for head CT. The effect of ATCM and bowtie filters was assessed. Depending on patient position, organ doses differed up to 22% for the supratentorial brain, 34% for the infratentorial brain, 19% for the eyes, 28% for the lungs, 25% for the stomach, and 22% for the liver compared with those in the 0-position. The relation between position and dose was linear and mainly affected by the bowtie filter in head CT, while it was quadratic and affected by ATCM and bowtie filter in thoracoabdominal CT. It further depended on the relative position of each organ to the isocenter. An inverse relation was found between position and image noise. Scatter radiation was not significantly related to patient positioning (p = 0.21). In pediatric CT, vertical patient positioning had a substantial impact on radiation dose with differences of up to 34%, depending on the body region and location of each individual organ. • Patient off-centering has a substantial impact on organ radiation dose and image noise in pediatric CT. • Impact of patient off-centering on radiation dose and noise differs between head and thoracoabdominal CT. • Differences are caused by both ATCM and bowtie filter in thoracoabdominal CT, but mainly by bowtie filter in head CT.

LOCAL DRLS FOR PAEDIATRIC CT EXAMINATIONS BASED ON SIZE-SPECIFIC DOSE ESTIMATES IN KERMANSHAH, IRAN.

Due to the radiosensitivity of paediatric patients to X-ray, it is necessary to survey the paediatric DRLs using size-specific dose estimates (SSDE). In the present study, we determined the local diagnostic reference levels (DRLs) for paediatric chest, head and abdomen-pelvis CT examinations and their Surview scans in Kermanshah city, Iran. For ≤1 year, 1-5 years, 5-10 years and 10-15 years the DRLs (mGy) based on SSDE were determined N/A, 6.00, 6.25, 8.27 for abdomen-pelvis, and 8.74, 7.45, 11.15, 10.45 for chest and 19.05, 18.33, 18.22, 20.14 for head examinations, respectively. The differences between body size and default phantom defined in CT scanners are significant and should be considered when determining the DRLs. Based on our findings, use of CTDIv and SSDE parameters for determining DRLs leads to significant different results in children; thus SSDE is suggested as a more accurate index than CTDIV for establishing DRLs in paediatric CT examinations.