Age-Dependent Changes in Effective Dose in Pediatric Brain CT: Comparisons of Estimation Methods.

Practical Strategies to Reduce Pediatric CT Radiation Dose

Introduction: Computed tomography (CT) is a medical imaging modality that produces 3-D cross-sectional images of tissues using several X-ray projections at different angles. Since its introduction in the 1970s, CT usage has been on the increase for both adults and pediatrics. A major challenge of this modality is the high doses of radiation exposure to patients, especially in pediatrics, who are more radiosensitive compared to adults. Hence, the need to ensure that radiation safety standards are adhered to. This will go a long way in reducing the adverse effects of radiation. The aim of this study was to assess the level of compliance to international dose reference levels (DRLs) in terms of effective doses in pediatric CT scans conducted in three Iraqi hospitals. Materials and Methods: CT brain and abdomen/pelvis examinations were conducted for pediatric patients aged between few months and 15 years in three Iraqi hospitals (Al Wasiti, Neuroscience and Al Omara). All scans were performed on a Somatom Sensation® 16 multidetector CT (MDCT) scanner with a Straton® X-ray tube (Siemens, Erlangen, Germany) utilising automatic tube current modulation (CARE Dose4DTM; Siemens, Erlangen, Germany). Volumetric CT dose index (CTDIvol) and dose length product (DLP) were collected for 180 patients (60 in each hospital). Afterwards, their effective doses were estimated from DLP values and compared with international DRLs. Results: Brain CT: The DLP values obtained for Al Wasiti, Neuroscience and Al Omara hospitals were in the range; 789-918.8 mGy.cm, 833-874.6 mGy.cm and 627.6-810 mGy.cm respectively, while their corresponding effective doses were in the range; 1.8-2.09 mSv, 1.9- 2.06 mSv and 1.43-1.83 mSv. Abdomen/Pelvis: The DLP values obtained for Al Wasiti, Neuroscience and Al Omara hospitals were in the range; 392.9-425.8 mGy.cm, 355-395 mGy.cm and 314.8-383.6 mGy.cm respectively, while their corresponding effective doses were in the range; 6.65-7.22 mSv, 6- 6.7 mSv and 5.34-6.51 mSv. Using the International Commission on Radiological Protection (ICRP) publication 103 as basis for assessing compliance level, for brain CT we observe slightly higher values in Al Wasiti and Neuroscience hospitals while Al Omara was similar to the international DRLs. However, for abdomen/pelvis CT examinations, the effective doses in all three hospitals were within the acceptable limits of international DRLs. Conclusion: This study has shown an encouraging level of compliance towards adequate radiation protection management in pediatric CT examinations among the three hospitals. Although, the best compliance level was observed in Al Omara hospital. Regular monitoring should be enforced to ensure that CT doses delivered to pediatric patients are as low as reasonably achievable without compromising diagnostic quality.

Establishment of diagnostic reference level for computed tomography of head pediatrics in Morocco: A pilot study

To determine conversion factors for the new International Commission on Radiological Protection (ICRP) publication 103 recommendations for adult and pediatric patients and to compare the effective doses derived from Monte Carlo calculations with those derived from dose-length product (DLP) for different body regions and computed tomographic (CT) scanning protocols. Effective dose values for the Oak Ridge National Laboratory phantom series, including phantoms for newborns; 1-, 5-, and 10-year-old children; and adults were determined by using Monte Carlo methods for a 64-section multidetector CT scanner. For each phantom, five anatomic regions (head, neck, chest, abdomen, and pelvis) were considered. Monte Carlo simulations were performed for spiral scanning protocols with different voltages. Effective dose was computed by using ICRP publication 60 and publication 103 recommendations. The calculated effective doses were compared with those derived from the DLP by using previously published conversion factors. In general, conversion factors determined on the basis of Monte Carlo calculations led to lower values for adults with both ICRP publications. Values up to 33% and 32% lower than previously published data were found for ICRP publication 60 and ICRP publication 103, respectively. For pediatric individuals, effective doses based on the Monte Carlo calculations were higher than those obtained from DLP and previously published conversion factors (eg, for chest CT scanning in 5-year-old children, an increase of about 76% would be expected). For children, a variation in conversion factors of up to 15% was observed when the tube voltage was varied. For adult individuals, no dependence on voltage was observed. Conversion factors from DLP to effective dose should be specified separately for both sexes and should reflect the new ICRP recommendations. For pediatric patients, new conversion factors specific for the spectrum used should be established.

Children are more radiosensitive than adults, making dose optimisation in paediatric computed tomography (CT) essential. Although Diagnostic Reference Levels (DRLs) are internationally recommended as optimisation tools, national DRLs for paediatric CT in Jordan remain limited and outdated. This study aimed to establish national DRLs for six paediatric CT protocols, evaluate inter-hospital and age-related dose variations, and compare results with international benchmarks. A retrospective multicentre study was conducted across six Jordanian hospitals between December 2023 and September 2025, including 3794 paediatric patients stratified into four age groups (< 1, 1-4, 5-10, and 11-18years). Volumetric CT dose index (CTDIvol) and dose-length product (DLP) data were collected for six protocols: brain, chest, abdomen-pelvis, chest-abdomen-pelvis, sinuses, and contrast-enhanced neck soft tissue. DRLs were defined as the 75th percentile of institutional median CTDIvol and DLP values. Inter-hospital and age group variations were analysed, and univariable regression analyses assessed acquisition parameters associated with dose variation. Dose increased with patient age for trunk protocols, whereas brain, sinuses, and neck CT showed comparatively stable patterns. Substantial inter-hospital variability was observed across protocols, with institutional median CTDIvol differing markedly between centres, particularly for trunk examinations in younger age groups. In univariable regression analyses, all four acquisition parameters (kVp, mAs, pitch, and slice thickness) were significantly associated with CTDIvol and DLP (p ≤ 0.001), with kVp demonstrating the strongest association (R2 = 0.603 for CTDIvol; R2 = 0.630 for DLP). Compared with published international DRLs, Jordanian brain CT dose metrics were higher in multiple age groups; chest comparisons should be interpreted cautiously where international benchmarks are weight-banded. This study established national paediatric CT DRLs for Jordan, highlighting the need for standardised protocols and periodic DRL review to enhance radiation protection.

Differences in using the international commission on radiological protection’s publications 60 and 103 for determining effective dose in paediatric CT examinations

Innovative Protocol Optimization for Radiation Dose Reduction in Pediatric Head CT Scan.

The aim of this study was to determine the conversion factors for the effective dose (ED) per dose length product (DLP) for various computed tomography (CT) protocols based on the 2007 recommendations of the International Commission on Radiological Protection (ICRP). CT dose data from 369 CT scanners and 13,625 patients were collected through a nationwide survey. Data from 3793 patients with a difference in height within 5% of computational human phantoms were selected to calculate ED and DLP. The anatomical CT scan ranges for 11 scan protocols (adult-10, pediatric-1) were determined by experts, and scan lengths were obtained by matching scan ranges to computational phantoms. ED and DLP were calculated using the NCICT program. For each CT protocol, ED/DLP conversion factors were calculated from ED and DLP. Estimated ED conversion factors were 0.00172, 0.00751, 0.00858, 0.01843, 0.01103, 0.02532, 0.01794, 0.02811, 0.02815, 0.02175, 0.00626, 0.00458, 0.00308, and 0.00233 mSv∙mGy−1∙cm−1 for the adult brain, intra-cranial angiography, C-spine, L-spine, neck, chest, abdomen and pelvis, coronary angiography, calcium scoring, aortography, and CT examinations of pediatric brain of <2 years, 4–6 years, 9–11 years, and 13–15 years, respectively. We determined ED conversion factors for 11 CT protocols using CT data obtained from a nationwide survey in Korea and Monte Carlo-based dose calculations.

To develop a set of conversion factors from dose length product (DLP) to effective dose (E) for pediatric and adult reference individuals undergoing computed tomography (CT) examinations. This study used 12 hybrid computational phantoms representing reference pediatric and adult individuals in compliance with the International Commission on Radiological Protection (ICRP) reference data. The phantoms were combined with a model of the Siemens Sensation 16 scanner, to compute organ doses from CT examinations using a radiation transport code, MCNPX2.7. Effective doses based on ICRP 60 and 103 tissue weighting factors were calculated. The DLP was derived from the scan length and Computed Tomography Dose Index (CTDI)vol. The resulting DLP-to-E conversion factors were analyzed. The results consist in a set of DLP-to-E conversion factors for head, chest, abdomen, abdomen-pelvis, and chest-abdomen-pelvis CT examinations for newborn, 1-, 5-, 10-, 15-year-old and adult reference phantoms, for 80, 100 and 120 kVp and for ICRP 60 and 103 tissue weighting factors. The DLP-to-E factors decrease with smaller tube potential, with the greatest decrease for the head examinations for which values at 80 kVp are 20% smaller than at 120 kVp on average. The ICRP 103 weighting factors, compared to ICRP 60, Result in variations of DLP-to-E from 0.8 to 1.2-fold with a systematic increase for the chest, 1.14- fold on average, due to the increased breast weighting factor. The DLP-to-E factors for the body examinations are relatively similar to each other but 5 to 12-fold higher than for the head exam. The factors decrease with age until 15 years and then slightly increase for adult except for head. An updated set of DLP-to-E conversion factors were established based on more realistic human phantoms and provide an improved accuracy to obtain effective dose from DLP for patients undergoing CT examinations.

The Image Gently in Dentistry campaign: promotion of responsible use of maxillofacial radiology in dentistry for children.

Background.Patients, especially children, are exposed to substantially high doses of ionising radiation during computed tomography (CT) procedures. Children are several times more susceptible to ionising radiation than adults. Diagnostic reference levels (DRLs) are an important tool for monitoring and optimising patient radiation exposure from radiological procedures. The aim of this study is to estimate the ionising radiation exposure doses and set local DRLs for head CT examinations according to age and to compare local DRLs with national and European DRLs and with literature data in other countries.Materials and methods.Scan parameters of single-phase head CT examinations were collected. Patients were grouped by age in the following intervals: <1, 1−5, 5−10, 10−15 and 15−18 years. Local age-based DRLs set as the 3rd quartile of the median dose-length product (DLP) were calculated. Literature analysis was performed on PubMed search engine on inclusion criteria: publication date 2015–2020, used keywords paediatric computed tomography, paediatric CT, diagnostic reference levels (DRLs). The 23 articles discussing paediatric DRLs were further analysed.Results.Data was collected from 194 paediatric head CT examinations performed in 2019. The median DLP values for head CT were 144.3, 233.7, 246.4, 288.9, 315.5 for <1, 1−5, 5−10, 10−15 and 15−18 years old groups. Estimated local DRLs for head CT examinations are 170, 300, 310, 320, 360 mGy*cm for <1, 1−5, 5−10, 10−15 and 15−18 years age groups respectively and 130, 210, 275, 320 mGy*cm for 0−3 months, 3 months−1 year, 1−6 years and ≥ 6 years age groups respectively. Conclusions.Results of this study showed that settled new local DRLs of head CT examinations were 2–4 times lower than national DRLs and about 2 times lower than European DRLs. Moreover, the study indicated that paediatric head CT doses are significantly lower in comparison with those indicated in the majority of published data from other hospitals over the last 6 years. Patient dose assessment and local DRLs establishment plays important role in future exposure optimisation.

Evaluation of age-based radiation dose in paediatric patients received from head CT examination at a tertiary hospital, Nigeria

ObjectivesThe objectives of this study were to: 1) evaluate patient radiation exposure in CT and 2) establish CT Diagnostic Reference Levels (DRL)s based on clinical indication (CI) in Qatar. Materials and MethodsPatient data for 13 CIs were collected using specially designed collection forms from the dose management software (DMS) of Hamad Medical Corporation (HMC), the main Qatar healthcare provider. The methodology described in the International Commission on Radiological Protection (ICRP) Report 135 was followed to establish national clinical DRLs in terms of Volumetric Computed Tomography Dose Index (CTDIvol) and total Dose Length Product (DLPt). Effective dose (Ef) was estimated by DMS using DLPt and appropriate conversion factors and was analyzed for comparison purposes. ResultsData were retrospectively collected for 896 adult patients undergoing CT examinations in 4 hospitals and 7 CT scanners. CT for Diffuse infiltrative lung disease imparted the lowest radiation in terms of CTDIvol (5 mGy), DLPt (181 mGy.cm) and Ef (3.6 mSv). Total body CT for severe trauma imparted the highest DLPt (3137 mGy.cm) and Ef (38.6 mSv) of all CIs with a CTDIvol of 15 mGy. Rounded Third quartile CTDIvol and DLPt values were defined as the Qatar CT clinical DRLs. Comparison was limited due to sparse international literature. When this was possible data were lower or comparable with other studies. ConclusionsThis is the first study reporting national clinical DRLs in Asia and second one internationally after UK. For accurate comparison between studies, systemized CI nomenclature must be followed by researchers.

Currently, computed tomographic (CT) imaging of the heart is mainly used for the quantification of coronary artery calcification as an indirect measure of coronary plaque burden1,2 and, less frequently, for minimally invasive coronary angiography.3 CT imaging of the heart and coronary arteries without unsharpness due to motion artifact first became possible with the introduction of electron beam computed tomography (EBCT) in 1983.4 More recently, so-called multislice spiral computed tomographic (MSCT) scanners with gantry rotation speeds fast enough to produce diagnostic images of the heart under certain conditions have become widely available.5 As a consequence, cardiac CT imaging, most often performed for the purpose of calcium scoring,2 is increasingly applied to the general public. In many centers, patients have access to such studies without physician referral. This has created concerns for public health because of the radiation dose associated with CT imaging.6–8 Many clinicians and researchers working with patients with cardiovascular diseases may yet be unfamiliar with the radiation doses that are received during various cardiac CT imaging protocols and how they differ between the various scanner types that are currently used. To further complicate matters, radiation dose estimates can be expressed in various ways. For these reasons, the doses reported in previous publications on cardiac CT have varied widely, and it is not always clear what parameters were being reported.3,9–11 The purpose of this article is to discuss the current concepts of radiation dose measurement and estimation in CT imaging and to provide comparative estimates for radiation doses received during cardiac examinations with use of EBCT or MSCT. This information may be helpful to physicians who perform calcium scoring, counsel patients contemplating cardiac calcium scoring, or are considering referring their patients for such studies. EBCT scanners acquire 1 scan at a time, using …

The purpose of this study is to determine the conversion factors that enable accurate estimation of the effective dose (ED) used for cardiac 64-MDCT angiography performed for children. Anthropomorphic phantoms representative of 1- and 10-year-old children, with 50 metal oxide semiconductor field-effect transistor dosimeters placed in organs, underwent scanning performed using a 64-MDCT scanner with different routine clinical cardiac scan modes and x-ray tube potentials. Organ doses were used to calculate the ED on the basis of weighting factors published in 1991 in International Commission on Radiological Protection (ICRP) publication 60 and in 2007 in ICRP publication 103. The EDs and the scanner-reported dose-length products were used to determine conversion factors for each scan mode. The effect of infant heart rate on the ED and the conversion factors was also assessed. The mean conversion factors calculated using the current definition of ED that appeared in ICRP publication 103 were as follows: 0.099 mSv · mGy-1 · cm-1, for the 1-year-old phantom, and 0.049 mSv · mGy-1 · cm-1, for the 10-year-old phantom. These conversion factors were a mean of 37% higher than the corresponding conversion factors calculated using the older definition of ED that appeared in ICRP publication 60. Varying the heart rate did not influence the ED or the conversion factors. Conversion factors determined using the definition of ED in ICRP publication 103 and cardiac, rather than chest, scan coverage suggest that the radiation doses that children receive from cardiac CT performed using a contemporary 64-MDCT scanner are higher than the radiation doses previously reported when older chest conversion factors were used. Additional up-to-date pediatric cardiac CT conversion factors are required for use with other contemporary CT scanners and patients of different age ranges.