Pediatric CT Research Articles

Diagnostic reference levels and achievable doses for common computed tomography examinations: Results from the Japanese nationwide dose survey.

To propose a new set of Japanese diagnostic reference levels (DRLs) and achievable doses (ADs) for 2017 and to verify the usefulness of Japanese DRLs (DRLs 2015) for CT, by investigating changes in the volume CT dose index (CTDIvol) from 2014 to 2017. Detailed information on the CT scan parameters used throughout Japan were obtained by questionnaire survey. The CTDIvol and dose-length product for the 11 commonest adult and 6 commonest paediatric CT examinations were surveyed and compared with 2014 data and DRLs 2015. Evaluations of adult head (helical), and abdomen and pelvis without contrast agent, paediatric chest without contrast agent, and abdomen and pelvis without contrast agent showed a slightly lower mean CTDIvol in 2017 than in 2014 (t-test, p < 0.05). The interquartile range of CTDIvol for all 2017 examinations was lower than in 2014. This study verified the lower mean, 75th percentile, and interquartile range by investigating changes in the CTDIvol from 2014 to 2017. The DRLs 2015 contributed to CT radiation dose reduction. The widespread implementation of iterative reconstruction algorithms and low-tube voltage in CT scanners is likely to facilitate further reduction in the CT radiation dose used in Japan. Although radiological technologists may require further education on appropriate CTDIvol and DLP usage, the DRLs 2015 greatly contributed to the reduction of the CT radiation dose used in Japan.

Radiation Dose Optimization in Pediatric Chest CT: Major Indicators of Dose Exposure in 1695 CT Scans over Seven Years.

To analyze possible influencing factors on radiation exposure in pediatric chest CT using different approaches for radiation dose optimization and to determine major indicators for dose development. In this retrospective study at a clinic with maximum care facilities including pediatric radiology, 1695 chest CT examinations in 768 patients (median age: 10years; range: 2 days to 17.9 years) were analyzed. Volume CT dose indices, effective dose, size-specific dose estimate, automatic dose modulation (AEC), and high-pitch protocols (pitch ≥ 3.0) were evaluated by univariate analysis. The image quality of low-dose examinations was compared to higher dose protocols by non-inferiority testing. Median dose-specific values annually decreased by an average of 12 %. High-pitch mode (n = 414) resulted in lower dose parameters (p < 0.001). In unenhanced CT, AEC delivered higher dose values compared to scans with fixed parameters (p < 0.001). In contrast-enhanced CT, the use of AEC yielded a significantly lower radiation dose only in patients older than 16years (p = 0.04). In the age group 6 to 15 years, the values were higher (p < 0.001). The diagnostic image quality of low-dose scans was non-inferior to high-dose scans (2.18 vs. 2.14). Radiation dose of chest CT was reduced without loss of image quality in the last decade. High-pitch scanning was an independent factor in this context. Dose reduction by AEC was limited and only relevant for patients over 16 years. · The radiation dose of pediatric chest CT was reduced in the last decade.. · High-pitch scanning is an independent factor of dose optimization.. · Dose reduction by AEC is limited and only relevant for older children.. · Esser M, Hess S, Teufel M et al. Radiation Dose Optimization in Pediatric Chest CT: Major Indicators of Dose Exposure in 1695 CT Scans over Seven Years. Fortschr Röntgenstr 2018; 190: 1131 - 1140.

Automated tube voltage selection in pediatric non-contrast chest CT.

BackgroundModern CT scanners provide automatic dose adjustment systems, which are promising options for reducing radiation dose in pediatric CT scans. Their impact on patient dose, however, has not been investigated sufficiently thus far.ObjectiveTo evaluate automated tube voltage selection (ATVS) in combination with automated tube current modulation (ATCM) in non-contrast pediatric chest CT, with regard to the diagnostic image quality.Materials and methodsThere were 160 non-contrast pediatric chest CT scans (8.7±5.4 years) analyzed retrospectively without and with ATVS. Correlations of volume CT Dose Index (CTDIvol) and effective diameter, with and without ATVS, were compared using Fisher’s z-transformation. Image quality was assessed by mean signal-difference-to-noise ratios (SDNR) in the aorta and in the left main bronchus using the independent samples t-test. Two pediatric radiologists and a general radiologist rated overall subjective Image quality. Readers’ agreement was assessed using weighted kappa coefficients. A p value <0.05 was considered significant.ResultsCTDIvol correlation with the effective diameter was r = 0.62 without and r = 0.80 with ATVS (CI: -0.04 to -0.60; p = 0.025). Mean SDNR was 10.88 without and 10.03 with ATVS (p = 0.0089). Readers’ agreement improved with ATVS (weighted kappa between pediatric radiologists from 0.1 (0.03–0.16) to 0.27 (0.09–0.45) with ATVS; between general and each pediatric radiologist from 0.1 (0.06–0.14) to 0.12 (0.05–0.20), and from 0.22 (0.11–0.34) to 0.36 (0.24–0.49)).ConclusionATVS, combined with ATCM, results in a radiation dose reduction for pediatric non-contrast chest CT without a loss of diagnostic image quality and prevents errors in manual tube voltage setting, and thus protecting larger children against an unnecessarily high radiation exposure.

Radiation Dose Reduction at Pediatric CT: Use of Low Tube Voltage and Iterative Reconstruction.

Given the growing awareness of and concern for potential carcinogenic effects of exposure of children to ionizing radiation at CT, optimizing acquisition parameters is crucial to achieve diagnostically acceptable image quality at the lowest possible radiation dose. Among currently available dose reduction techniques, recent technical innovations have allowed the implementation of low tube voltage scans and iterative reconstruction (IR) techniques into daily clinical practice for pediatric CT. The benefits of lowering tube voltage include a considerable reduction in radiation dose and improved contrast on images, especially when an iodinated contrast medium is used. The increase in noise, which is attributed to decreased photon penetration, is a major drawback but is not as severe as that at adult CT because of the small body size of children. In addition, use of IR algorithms can suppress increased noise, yielding wider applicability for low tube voltage scans. However, a careful implementation strategy and methodologic approach are necessary to maximize the potential for dose reduction while preserving diagnostic image quality under each clinical condition. The potential pitfalls of and topics related to these techniques include (a) the effect of tube voltage on the surface radiation dose, (b) the effect of window settings, (c) accentuation of metallic artifacts, (d) deterioration of low contrast detectability at low-dose settings, (e) interscanner variation of x-ray spectra, and (f) a comparison with the use of a spectral shaping technique. Appropriate use of low tube voltage and IR techniques is helpful for radiation dose reduction in most applications of pediatric CT. Online DICOM image stacks are available for this article . ©RSNA, 2018.

Invited Commentary on “Radiation Dose Reduction in Pediatric CT,” with Response from Dr Nagayama et al

Invited Commentary on “Radiation Dose Reduction in Pediatric CT,” with Response from Dr Nagayama et al

Appropriate use of a beta-blocker in paediatric coronary CT angiography.

There is no standard dose or protocol for beta-blocker administration as preconditioning in children undergoing coronary CT angiography. A total of 63 consecutive patients, with a mean age of 10.0±3.1 years, who underwent coronary CT angiography to assess possible coronary complications were enrolled in a single-centre, retrospective study. All patients were given an oral beta-blocker 1 hour before coronary CT angiography. Additional oral beta-blocker or intravenous beta-blocker was given to those with a high heart rate. We compared image quality, radiation exposure, and adverse events among the patients without additional beta-blocker, with additional oral beta-blocker, and with additional intravenous beta-blocker. There were no significant differences in image quality or radiation exposure among the groups. The heart rate just before scanning was significantly correlated with image quality (p<0.001, r=-0.533) but was not correlated with radiation exposure (p=0.45, r=0.096). There were no adverse events related to any allergic reaction, thereby showing the effectiveness of the beta-blocker. Initial oral beta-blocker administration (0.8 mg/kg/dose) should be administered to all children undergoing coronary CT angiography. Additional intravenous beta-blocker should be given to those with poor heart rate control to improve image quality without increasing radiation exposure or allowing adverse events.

P033] Evaluation, comparison and optimization of the effects of manual versus software automated protocols on radiation dose and image quality in paediatric chest computed tomography

Purpose The aim of this study was to compare software automated versus radiologist manual CT protocols optimization strategies by using a CT phantom with different acquisition parameters and iterative reconstruction (IR) levels in order to maintain high image quality while decreasing dose and image noise. Methods A CATPHAN CT phantom underwent simulated pediatric chest CT scans using both automated and manual parameters optimization approaches performed by a radiologist. Phantom was scanned within different protocols varying kV, mAs, pitch, IR. The subjective and objective image qualities were assessed by both radiologists and software. Computed tomography dose index (CTDI) and dose-length product (DLP) values were collected and analysed. Equivalent dose to organ at risk (OAR) was assessed with a Monte Carlo system using a digital phantom simulating a six year old pediatric patient. Results Dose to OAR, CTDIvol and DLP were substantially lower (90%, 58% and 32% respectively) adopting a manual approach, maintaining a good subjective image quality as demonstrated by a human visual scoring test evaluation on images. Through CT acquisitions, linearity and resolution were constant while image noise (mean −6.4, standard deviation 10.1) and uniformity (mean −6.4, standard deviation 10.1,) varied between scans, as observed by 3 experienced radiologists by visual score analysis. Iterative reconstruction was associated with a further dose reduction using level 3 (max 6) in order to avoid texture effect. Conclusions In a simulated pediatric chest CT study, radiologist guided acquisition resulted the best choice in terms of optimal dose-image quality ratio while maintaining good image quality.

Estimation of conversion coefficients for absorbed and effective doses for pediatric CT examinations in two different PET/CT scanners

Normally, during medical procedures, special attention must be given to pediatric patients when compared to adults. This is specially relevant during procedures involving ionizing radiation, as CT scans, given that children are considerably more sensitive to radiation induced stochastic effects than adults. In order to investigate the radiation doses on radiosensitive organs of pediatric patients, undergoing head, chest and abdomen CT procedures, numerical dosimetry was employed in this work. The novelty is the use of a new set of pediatric virtual anthropomorphic phantoms, coupled with Monte Carlo simulation, to determine the conversion coefficients for absorbed and effective doses. Two CT equipment were simulated, taking into account the main characteristics of those commercially available. The results were converted to conversion coefficients (mGy/100 mA) for several organs and tissues, and the highest values were obtained for the newborn phantom. This numerical approach employed a new and reliable technique for pediatric CT dosimetry.

Reducing the radiation exposure from CT scanning in children with shunts: a nationwide survey and a departmental CT protocol

Introduction: Low dose ionising radiation such as from CT scans carries a low but cumulative risk of cancer and children are particularly sensitive. Children with VP Shunts often undergo multiple CT scans. We developed a CT protocol with reduced radiation for paediatric patients with shunts and compared it with the current practice in the other neurosurgical units in the UK and ROI by conducting a nationwide survey.Methods: An email questionnaire was send to the superintendent radiographer in every Neurosurgical unit in the UK and the ROI.Results: The response rate was 70%. Only 5 (19%) of the responding units used a dedicated CT shunt protocol with reduced radiation. Radiation was reduced by lowering the tube current. In comparison, our protocol uses a combination of less tube current and fewer slices. This reduced the radiation exposure of a CT head significantly with sufficient image quality to make a diagnosis.Conclusion: Radiation from CT for paediatric shunt patients scans can and should be reduced. This can be achieved by using reduced radiation protocols. A national paediatric CT shunt protocol could lead to significant reduction in effective radiation dose.

Multiphase acquisitions in pediatric abdominal-pelvic CT are a common practice and contribute to unnecessary radiation dose.

Many patients at our pediatric hospital have had a contrast-enhanced CT of the abdomen and pelvis performed by an outside imaging facility before admission. We have noticed that many of these exams are multiphase, which may contribute to unnecessary radiation dose. To determine the frequency of multiphase acquisitions and radiation dose indices in contrast-enhanced CTs of the abdomen and pelvis performed by outside imaging facilities in patients who were subsequently transferred to our pediatric hospital for care, and compare these metrics to contrast-enhanced CTs of the abdomen and pelvis performed internally. A retrospective analysis was performed of contrast-enhanced CTs of the abdomen and pelvis from outside imaging facilities uploaded to our picture archiving and communication system (PACS) between January 1, 2012, and December 31, 2015. CT images and dose pages were reviewed to determine the number of phases and dose indices (CT dose index-volume [CTDIvol], dose-length product, size-specific dose estimate). Exams for abdominal or pelvic mass, trauma or urinary leak indications were excluded. Data were compared to internally acquired contrast-enhanced CTs of the abdomen and pelvis by querying the American College of Radiology (ACR) Dose Index Registry. This review was institutional review board and HIPAA compliant. There were 754 contrast-enhanced CTs of the abdomen and pelvis from 104 outside imaging facilities. Fifty-three percent (399/754) had 2 phases, and 2% (14/754) had 3 or more phases. Of the 939 contrast-enhanced CTs of the abdomen and pelvis performed internally, 12% (115) were multiphase exams. Of 88% (664) contrast-enhanced CTs of the abdomen and pelvis from outside imaging facilities with dose data, CTDIvol was 2.7 times higher than our institution contrast-enhanced CTs of the abdomen and pelvis (939) for all age categories as defined by the ACR Dose Index Registry (mean: 9.4 vs. 3.5mGy, P<0.0001). The majority (74%) of multiphase exams were performed by 9 of 104 outside imaging facilities. Multiphase acquisitions in routine contrast-enhanced CT of the abdomen and pelvis exams at outside imaging facilities are more frequent than those at a dedicated pediatric institution and contribute to unnecessary radiation dose. A contrast-enhanced CT of the abdomen and pelvis exam from an outside imaging facility with two passes may have as much as four times to six times the dose as the same exam performed with a single pass at a pediatric imaging center. We advocate for imaging facilities with high multiphase rates to eliminate multiple phases from routine contrast-enhanced CT of the abdomen and pelvis exams in children.

Noncontrast Head CT in Children: National Variation in Radiation Dose Indices in the United States.

Radiologists should manage the radiation dose for pediatric patients to maintain reasonable diagnostic confidence. We assessed the variation in estimated radiation dose indices for pediatric noncontrast head CT in the United States. Radiation dose indices for single-phase noncontrast head CT examinations in patients 18 years of age and younger were retrospectively reviewed between July 2011 and June 2016 using the American College of Radiology CT Dose Index Registry. We used the reported volume CT dose index stratified by patient demographics and imaging facility characteristics. The registry included 295,296 single-phase pediatric noncontrast head CT studies from 1571 facilities (56% in male patients and 53% in children older than 10 years of age). The median volume CT dose index was 33 mGy (interquartile range = 22-47 mGy). The volume CT dose index increased as age increased. The volume CT dose index was lower in children's hospitals (median, 26 mGy) versus academic hospitals (median, 32 mGy) and community hospitals (median, 40 mGy). There was a lower volume CT dose index in level I and II trauma centers (median, 27 and 32 mGy, respectively) versus nontrauma centers (median, 40 mGy) and facilities in metropolitan locations (median, 30 mGy) versus those in suburban and rural locations (median, 41 mGy). Considerable variation in the radiation dose index for pediatric head CT exists. Median dose indices and practice variations at pediatric facilities were both lower compared with other practice settings. Decreasing dose variability through proper management of CT parameters in pediatric populations using benchmarks generated by data from registries can potentially decrease population exposure to ionizing radiation.

Evaluating Lens Dose Reduction in Pediatric Neuroradiology Examinations Using Automated Kilovoltage Selection Software.

The purpose of this study is to evaluate the potential of an automated kilo-voltage selection software for the reduction of lens dose in pediatric CT scans. Two metal oxide semiconductor field effect transistor (MOSFET) detectors measured the lens dose in two anthropomorphic 1- and 5-year-old phantoms. These phantoms were scanned using a clinical pediatric brain protocol at 120 kVp as a control with the MDCT scanner. Scans were then repeated using automated kilovoltage software. The automated kilovoltage was set to operate at tube potentials of 120, 110, and 100 kVp. Dose savings were compared with the average lens dose of both eyes between automated kilovoltage and the control setting. Image quality was studied by contrast-to-noise ratios (CNRs) for each setting. The mean (± SD) lens dose from the routine brain scan without automated kilovoltage was 0.92 ± 0.03 cGy and 0.81 ± 0.03 cGy for the 1- and 5-year-old phantoms, respectively. Use of the automated kilovoltage software at 120 kVp, 110 kVp, and 100 kVp resulted in dose reductions of 9.8%, 17.4%, and 19.6%, respectively, for the 1-year-old phantom and 1.2%, 8.6%, and 17.3%, respectively, for the 5-year-old phantom. The CNR for all automated kilovoltage scans was within 11% of the control scans for the 1-year-old and within 6% for the 5-year-old phantom. Our results show that automated kilovoltage software is effective for reducing the radiation dose to the lens of the eye in pediatric patients. Furthermore, the image quality by CNR remained acceptable within 11% of the baseline for all kilovoltage settings used.

Fully automated tissue classifier for contrast-enhanced CT scans of adult and pediatric patients

To develop a consistent, fully-automated classifier for all tissues within the trunk and to more accurately discriminate between tissues (such as bone) and contrast medium with overlapping high CT numbers.Twenty-eight contrast enhanced NCAP (neck-chest-abdomen-pelvis) CT scans (four adult and three pediatric patients) were used to train and test a tissue classification pipeline. The classifier output consisted of six tissue classes: lung, fat, muscle, solid organ, blood/bowel contrast and bone. The input features for training were selected from 28 2D image filters and 12 3D filters, and one hand crafted spatial feature. To improve differentiation between tissue and blood/bowel contrast classification, 70 additional CT images were manually classified. Two different training data sets consisting of manually classified tissues from different locations in body were used to train the models. Training used the random forest algorithm in WEKA (Waikato Environment for Knowledge Analysis); the number of trees was optimized for best out-of-bag error. Automated classification accuracy was compared with manual classification by calculating dice similarity coefficient (DSC).Model performance was tested on 21 manually classified slices (two adult and one pediatric patient). The overall DSC at image locations represented in the training dataset were—lung: 0.98, fat: 0.90, muscle: 0.85, solid organ: 0.75, blood/contrast: 0.82, and bone: 0.90. The overall DSC for slice locations that were not represented in the training dataset were—lung: 0.97, fat: 0.89, muscle: 0.76, solid organ: 0.79, blood: 0.56, and bone: 0.74. Analyzing the classification maps for the entire scan volume revealed that except for misclassifications in the trabecular bone region of the spinal column, and solid organ and blood/contrast interfaces within the abdomen, the results were acceptable.A fully-automated whole-body tissue classifier for adult and pediatric contrast-enhanced CT using random forest algorithm and intensity-based image filters was developed.

Derivation of new diagnostic reference levels for neuro-paediatric computed tomography examinations in Switzerland

Purpose. Definition of new national diagnostic reference levels (DRLs) for volume computed tomography dose index (CTDIvol) and dose length product (DLP) for neuro-paediatric CT examinations depending on the medical indication. Methods. Paediatric cranial CT data sets acquired between January 2013 and December 2016 were retrospectively collected between July 2016 and March 2017 from eight of the largest university and cantonal hospitals that perform most of the neuro-paediatric CTs in Switzerland. A consensus review of CTDIvol and DLP was undertaken for three defined anatomical regions: brain, facial bone, and petrous bone, each with and without contrast medium application. All indications for cranial CT imaging in paediatrics were assigned to one of these three regions. Descriptive statistical analysis of the distribution of the median values for CTDIvol and DLP yielded values in the minimum, maximum, 25th percentile (1st quartile), median (2nd quartile), and 75th percentile (3rd quartile). New DRLs for neuro-paediatric CT examinations in Switzerland were based on the 75th percentiles of the distributions of the median values of all eight centres. Where appropriate, values were rounded such that the DRLs increase or at least remain constant as the age of the patient increases. Results. Our results revealed DRLs for CTDIvol and DLP up to 20% lower than the DRLs used so far in Switzerland and elsewhere in Europe. Conclusions. This study provides Swiss neuro-paediatric CT DRL values to establish optimum conditions for paediatric cranial CT examinations. Periodic national updates of DRLs, following international comparisons, are essential.

Image based simulation of the low dose computed tomography images suggests 13 mAs 120 kV suitability for non-syndromic craniosynostosis diagnosis without iterative reconstruction algorithms

ObjectivesThe aim of this study was to simulate low dose paediatric head CT images with different noise levels corresponding to various tube current time product values and assess simulated image suitability in non-syndromic craniosynostosis diagnostics. Method29 paediatric patients who underwent head CT examinations for cranial deformity were enrolled in the study. The low dose CT images, corresponding to 120 kV and 120 mAs, 100 mAs, 80 mAs, 50 mAs and 13 mAs settings, were synthesised by adding noise to original data. Three researchers evaluated suitability for diagnostics of original and simulated images by using questionnaire assessing image suitability. Result174 separate cases (containing 1 axial and 1 3D image) were evaluated. Percentage of images evaluated as suitable for diagnosis were 98.9% on original images, 100% on 120 mAs, 100% on 100 mAs, 97.1% on 80 mAs, 96.6% on 50 mAs and 96% on 13 mAs. ConclusionsImages registered with 120 kV 13 mAs can be used to diagnose non-syndromic craniosynostosis with statistically same accuracy as with standard protocol and correspond to decrease of effective dose from 4.98 mSv to 0.33 mSv (median values).

Oral Contrast Agents for Pediatric CT and MR Enterography: It's a Matter of Good Taste.

Oral Contrast Agents for Pediatric CT and MR Enterography: It's a Matter of Good Taste.

Pediatric CT Protocols From the American Association of Physicists in Medicine Alliance for Quality CT

Pediatric CT Protocols From the American Association of Physicists in Medicine Alliance for Quality CT

RADIATION DOSE AND IMAGE QUALITY IN PEDIATRIC HEAD CT.

Our goal was to define a pediatric head CT protocol able to provide images of diagnostic quality, using the least amount of radiation, in children <10 years of age, while using a filtered back projection reconstruction algorithm. Image quality of 119 pediatric head CTs was assessed using a 5-point scoring system. Exams with scores ≥2.5 were considered of sufficient diagnostic quality. The contrast-to-noise ratio (CNR) was also measured. For children <1 year and 1-9 years, all studies performed with CTDIvol ≥ 20.1 mGy (range: 9-46 mGy) and CTDIvol ≥ 27.5 mGy (range: 15-60 mGy) yielded images of diagnostic quality. All diagnostic studies had a minimum CNR of 1.4. These CTDIvol values represent a good balance between image quality and radiation burden. This information can be helpful in designing pediatric head CT protocols with further dose-reduction, namely, iterative reconstruction algorithms and automated exposure control.

What is the underestimation of radiation dose to the pediatric thyroid gland from contrast enhanced CT, if contrast medium uptake is not taken into account?

PurposeTo assess the underestimation of radiation dose to the thyroid of children undergoing contrast enhanced CT if contrast medium uptake is not taken into account. Methods161 pediatric head, head & neck and chest CT examinations were retrospectively studied to identify those involving pre- and post-contrast imaging and thyroid inclusion in imaged volume. CT density of thyroid tissue in HU was measured in non-enhanced (NECT) and corresponding contrast-enhanced CT (CECT) images. Resulting CT number increase (ΔHU) was recorded for each patient and corresponded to a % w/w iodine concentration. The relation of %w/w iodine concentration to %dose increase induced by iodinated contrast uptake was derived by Monte Carlo simulation experiments. ResultsThe thyroid gland was visible in 11 chest and 3 neck CT examinations involving both pre- and post-contrast imaging. The %w/w concentration of iodine in the thyroid tissue at the time of CECT acquisition was found to be 0.13%–0.58% w/w (mean = 0.26%). The %increase of dose to thyroid tissue was found to be linearly correlated to%w/w iodine uptake. The increase in radiation dose to thyroid due to contrast uptake ranged from 12% to 44%, with a mean value of 23%. ConclusionsThe radiation dose to the pediatric thyroid from CECT exposure may be underestimated by up to 44% if contrast medium uptake is not taken into account. Meticulous demarcation of imaged volume in pediatric chest CT examinations is imperative to avoid unnecessary direct exposure of thyroid, especially in CT examinations following intravenous administration of contrast medium.

Low-dose paediatric cardiac and thoracic computed tomography with prospective triggering: Is it possible at any heart rate?

ObjectiveTo demonstrate that the use of step-and-shoot (SAS) mode in paediatric cardiac CT angiography (CCTA) is possible at heart rates (HR) greater than 65 bpm, allowing low-dose acquisition with single-source 64-slices CT. MethodsWe retrospectively included 125 paediatric patients (0–6 years). CCTA was performed with SAS at diastolic phase in 31 patients (group D, HR < 65 bpm), at systolic phase in 45 patients (group S, HR ≥ 65 bpm) and with non-gated mode in 49 patients (group NG). Effective dose (ED) and image quality using a 3-grade scoring scale (1, excellent; 2, moderate; 3, insufficient) of group S were compared with group D for coronary examinations and group NG for entire thorax vascular anatomy. ResultsFor coronary indications, median ED was 0.6 mSv in group D versus 0.9 mSv in group S (p < 0.01). For whole thorax indications, median ED was 2.7 mSv in group NG versus 1.1 mSv in group S (p < 0.001). The mean image quality score was (1.4 ± 0.6) points in group D, (1.4 ± 0.7) in group S for coronary indications (p = 0.9), (1.3 ± 0.6) in group S for whole thorax indications and (2.0 ± 0.0) in group NG (p < 0.001). ConclusionSAS mode is feasible in children with HR greater than 65 bpm allowing low-dose CCTA. It provided comparable image quality in systole, compared to diastole. SAS at the systolic phase provided better image quality with less radiation dose compared to non-gated scans for whole thorax examinations.