Helical CT of the body: are settings adjusted for pediatric patients?

An Overview on the Alignment of Radiation Protection in Computed Tomography with Maqasid al-Shari'ah in the Context of al-Dharuriyat

The increasing utilisation of computed tomography (CT) in the medical field has raised a greater concern regarding the radiation-induced health effects as CT imposes high radiation risks on the exposed individual. Adherence to radiation protection measures in CT as endorsed by regulatory bodies; justification, optimisation and dose limit, is essential to minimise radiation risks. Islam values every human being and Maqasid al-Shari'ah helps to protect human beings through its sacred principles which aim to fulfil human beings' benefits (maslahah) and prevent mischief (mafsadah). Alignment of the concept of radiation protection in CT within the framework of al-Dharuriyat; protection of faith or religion (din), protection of life (nafs), protection of lineage (nasl), protection of intellect ('aql) and protection of property (mal) is essential. This strengthens the concept and practices of radiation protection in CT among radiology personnel, particularly Muslim radiographers. The alignment provides supplementary knowledge towards the integration of knowledge fields between Islamic worldview and radiation protection in medical imaging, particularly in CT. This paper is hoped to set a benchmark for future studies on the integration of knowledge between the Islamic worldview and radiation protection in medical imaging in terms of other classifications of Maqasid al-Shari'ah; al-Hajiyat and al-Tahsiniyat.

The use of MRI in the study of patients with idiopathic scoliosis: a systematic review of the literature

Objective. To analyze the frequency of hidden neuraxial pathology in idiopathic scoliosis (IS), to substantiate the need for MRI in IS and to identify promising areas for the use of MRI in the examination of patients with IS.Material and Methods. The literature review was carried out using the PubMed and Google Scholar databases. Of the 780 papers on the research topic, 65 were selected after removing duplicates and checking for inclusion/exclusion criteria. As a result, 49 original studies were included in the analysis. Level of evidence – II.Results. According to modern literature, the main direction of using MRI in idiopathic scoliosis is the search for predictors of latent pathology of the spinal cord and craniovertebral junction. The frequency of neuraxial pathology in idiopathic scoliosis is 8 % for adolescent IS and 16 % for early IS. The main predictors of neuraxial pathology are male sex, early age of deformity onset, left-sided thoracic curve and thoracic hyperkyphosis. MRI in IS may be a useful addition to radiological diagnostic methods to identify risk factors and to study degenerative changes in the spine.Conclusion. MRI of the spine should be performed in the early stages of IS to detect latent spinal cord tethering. In type I Chiari anomalies, there is a possibility that early neurosurgery can prevent the development of scoliosis. The main signs of latent neuraxial pathology in IS are early progression of spinal deformity, left-sided thoracic curve, male gender and thoracic kyphosis over 40° according to Cobb.MRI can be used as an effective non-invasive tool in research aimed at identifying risk factors for IS, including helping to track early degeneration of intervertebral discs.

The Pattern of CT Scan Use in the Diagnosis of Abdominal Pain in Children Presenting to the Emergency Department of a Tertiary Community Hospital

Background and objective

Pediatric populations are highly sensitive to ionizing radiations and, therefore, are more at risk of their harmful outcomes. Our study aimed to determine the percentage of children who underwent a CT scan after presenting to the ED with abdominal pain. The secondary aim was to determine the change in management related to the CT results. In addition, we also wanted to determine the predictors associated with the use of abdominal CT scans in the evaluation of children presenting to ED with abdominal pain as well as the predictors associated with positive CT scan results in children with abdominal pain.

Materials and methods

We retrospectively reviewed the medical records of children with abdominal pain seen in our ED from 01/01/2011 through 12/30/2012. Patients aged 4-18 years presenting with abdominal pain were identified from the medical records. Data on demographics, clinical characteristics, associated factors, CT use, CT findings, and change in management were collected. Data were analyzed using Chi-square (χ²) analysis and Student’s t-test.

Results

A total of 1,780 charts were reviewed and 1,272 children were included in the study. The mean age of the cohort was 12.6 ± 4.6 years; 62.6% were female and 68.7% were African American. Of note, 14% (181/1,272) of the study group had received a CT scan; change in medical management was noted in 34.8% (63/181) of the scanned patients. Predictors of CT use included older age (p<0.0001), male gender (p<0.0001), white race (p<0.0001), an attending without advanced training in pediatric emergencies (p=0.001), acute onset of symptoms (p<0.0001), higher pain score (p<0.0001), right lower quadrant pain (p<0.0001), abdominal wall rebound tenderness (p<0.0001), abdominal tenderness (p<0.0001), fever (p<0.0001), and absence of constipation (p=0.04). Positive CT scan results were predicted by the presence of fever (p=0.013), lack of constipation (p=0.025), and white race (p=0.022). A multivariate analysis could not be done because not all data were available for each patient.

Conclusion

The use of the CT scan in children with abdominal pain affected the management in one out of three patients (34.8%). Fever, constipation, and white race were the factors associated with an increased likelihood of performing a CT scan and were also linked to positive results.

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.

Differences in radiation dose for computed tomography of the brain among pediatric patients at the emergency departments: an observational study

BACKGROUND

Computed tomography (CT) is associated with a risk of cancer development. Strategies to reduce radiation doses vary between centers. We compared radiation doses of CT brain studies between pediatric and general emergency departments (EDs), and determine the proportion studies performed within the reference levels recommended by the International Commission on Radiological Protection (ICRP).

METHODS

A retrospective review was carried out in a healthcare network consisting of one pediatric ED and three general hospital EDs. Pediatric patients less than 16 years old with CT brain studies performed between 1 January 2015 and 31 December 2018 were included. Information on demographic, diagnosis, volume-averaged computed-tomography dose index and dose length product (DLP) were collected. Effective dose was then calculated from DLP using conversion factors, termed k-coefficients which were derived using a 16 cm head CT dose phantom.

RESULTS

Four hundred and seventy-nine CT brain studies were performed - 379 (79.1%) at the pediatric ED. Seizure (149, 31.1%), head injury (147, 30.7%) and altered mental status (44, 9.2%) were the top three ED diagnoses. The median effective dose estimates were higher in general than pediatric EDs, particularly for those aged > 3 to ≤6 years old [1.57 mSv (IQR 1.42-1.79) versus 1.93 mSv (IQR 1.51-2.28), p = 0.047], > 6 to ≤10 years old [1.43 mSv (IQR 1.27-1.67) versus 1.94 mSv (IQR 1.61-2.59), p = 0.002) and > 10 years old (1.68 mSv (IQR 1.32-1.72) versus 2.03 mSv (IQR 1.58-2.88), p < 0.001). Overall, 233 (48.6%) and 13 (2.7%) studies were within the reference levels recommended by ICRP 60 and 103 respectively.

CONCLUSIONS

Radiation doses for CT brain studies were significantly higher at general EDs and less than half of the studies were within the reference levels recommended by ICRP. The development of diagnostic reference levels (DRLs) as a benchmark and clinical justification for performing CT studies can help reduce the radiation risks in the pediatric population.

Magnetic Resonance Imaging for the diagnosis and management of acute colonic diverticulitis: a review of current and future use

Diverticular disease is one of the most common causes of outpatient visits and hospitalisations across Australia, North America and Europe. According to the Gastroenterological Society of Australia (GESA, 2010), approximately 33% of Australians over 45 years of age and 66% over 85 years of age have some form of colonic diverticulosis. Patients with colonic diverticulosis are known to develop subsequent complications such as acute colonic diverticulitis (ACD), and when more than one attack of diverticulitis occurs, there is a 70-90% chance that the individual will experience ongoing problems and recurring infections throughout their lifetime. Medical imaging is fundamental in the diagnosis, treatment and ongoing management of ACD and its complications, with Computed Tomography (CT) identified as the prevailing gold standard in the last few decades. Cross-database searching highlighted a large gap in the literature regarding the effectiveness of Magnetic Resonance Imaging (MRI) as a non-ionising radiation alternative imaging tool for ACD imaging after the mid-2000s, despite ongoing technological advancements in this modality. This narrative review identified 13 key publications (11 primary prospective cohort studies, 1 systematic review and 1 meta-analysis) that evaluate MRI for ACD imaging, of which five were published within the last decade. Several existing MRI protocols are deemed suitable for ACD imaging, and it is recommended they be re-evaluated in larger cohorts. Future studies should consider the rapidly growing technological improvements of MRI, its cost efficiency and its applicability in modern day healthcare settings when addressing ACD management. This is especially important considering the gradual rise in radiation dose among the Australian population attributable to increased CT referrals, alongside increased reporting of ACD cases in younger individuals.

Computed tomography associated radiation exposure in children with craniosynostosis

BACKGROUND

The role of computed tomography (CT) for diagnosis and surgical planning for craniosynostosis (CS) is well-established. The aim of this study was to quantify the cumulative medical radiation exposure from CT in patients with CS at a tertiary care children's hospital.

METHODS

Medical records of patients who presented at < 2 years of age and underwent surgical intervention for CS were examined for demographic information. Effective radiation dose (ERD) in mSv was calculated for each head CT. Descriptive statistics and ANOVA were performed. Mean ± SD is reported; p < 0.05 was considered significant.

RESULTS

Two hundred seventy-two patients met inclusion criteria: 241 nonsyndromic and 31 with syndromic diagnoses. For nonsyndromic patients, mean age at first head CT was 6.0 ± 4.9 months, mean number of CT scans obtained was 2.1 ± 1.1, and the mean total combined ERD was 9.1 ± 4.8 mSv. CT scans obtained at < 6 months of age had a significantly greater ERD than those obtained at > 6 months, 5.3 ± 1.9 versus 4.3 ± 1.4 mSv, respectively (p = 0.001).

CONCLUSIONS

Patients with nonsyndromic CS undergo 2 CT scans on average related to their diagnosis, with a mean total ERD of 9.1 mSv; this is equivalent to 1.5 years of the average annual background radiation dose a person living in the USA will encounter from environmental radiation, medical exposures, and consumer products. A CT obtained at < 6 months is associated with a higher ERD; thus, we recommend delaying imaging from the initial presentation to the time of pre-operative planning when possible.

Influence of Different Arm Positions in the Localizer Radiograph(s) on Patient Dose during Exposure-Controlled CT Examinations of the Neck to Pelvis

Our aim was to examine the impact of different arm positions during imaging of the localizer radiograph(s) on effective dose for exposure-controlled computed tomography (CT) (Siemens/Canon) scans of the neck to pelvis. An anthropomorphic whole-body phantom was scanned from the neck to pelvis with the arms positioned in three different ways during the acquisition of the localizer radiograph: (i) above the head, (ii) alongside the trunk, and (iii) along the trunk with the hands placed on the abdomen. In accordance with clinical routines, the arms were not included in the subsequent helical scans. Effective doses were computed to a standard-sized patient (male/female) using a dedicated system-specific Monte Carlo-based software. Effective doses for the Canon CT scanner for the different alternatives (male/female) were (a) 5.3/6.62 mSv, (b) 5.62/7.15 mSv and (c) 5.92/7.44 mSv. For the Siemens CT scanner, effective doses were (a) 4.47/5.59 mSv, (b) 5.4/6.69 mSv and (c) 5.7/6.99 mSv. Arms placed above the head during localizer radiograph imaging in the current CT procedures substantially reduced the total effective dose to the patient.

Dose Estimation for the European Epidemiological Study on Pediatric Computed Tomography (EPI-CT)

Within the European Epidemiological Study to Quantify Risks for Paediatric Computerized Tomography (EPI-CT study), a cohort was assembled comprising nearly one million children, adolescents and young adults who received over 1.4 million computed tomography (CT) examinations before 22 years of age in nine European countries from the late 1970s to 2014. Here we describe the methods used for, and the results of, organ dose estimations from CT scanning for the EPI-CT cohort members. Data on CT machine settings were obtained from national surveys, questionnaire data, and the Digital Imaging and Communications in Medicine (DICOM) headers of 437,249 individual CT scans. Exposure characteristics were reconstructed for patients within specific age groups who received scans of the same body region, based on categories of machines with common technology used over the time period in each of the 276 participating hospitals. A carefully designed method for assessing uncertainty combined with the National Cancer Institute Dosimetry System for CT (NCICT, a CT organ dose calculator), was employed to estimate absorbed dose to individual organs for each CT scan received. The two-dimensional Monte Carlo sampling method, which maintains a separation of shared and unshared error, allowed us to characterize uncertainty both on individual doses as well as for the entire cohort dose distribution. Provided here are summaries of estimated doses from CT imaging per scan and per examination, as well as the overall distribution of estimated doses in the cohort. Doses are provided for five selected tissues (active bone marrow, brain, eye lens, thyroid and female breasts), by body region (i.e., head, chest, abdomen/pelvis), patient age, and time period (1977-1990, 1991-2000, 2001-2014). Relatively high doses were received by the brain from head CTs in the early 1990s, with individual mean doses (mean of 200 simulated values) of up to 66 mGy per scan. Optimization strategies implemented since the late 1990s have resulted in an overall decrease in doses over time, especially at young ages. In chest CTs, active bone marrow doses dropped from over 15 mGy prior to 1991 to approximately 5 mGy per scan after 2001. Our findings illustrate patterns of age-specific doses and their temporal changes, and provide suitable dose estimates for radiation-induced risk estimation in epidemiological studies.

Clinical concordance with Image Gently guidelines for pediatric computed tomography: a study across 663,417 CT scans at 53 clinical facilities

BACKGROUND

Managing patient radiation dose in pediatric computed tomography (CT) examinations is essential. Some organizations, most notably Image Gently, have suggested techniques to lower dose to pediatric patients and mitigate risk while maintaining image quality.

OBJECTIVE

We sought to validate whether institutions are observing Image Gently guidelines in practice.

MATERIALS AND METHODS

Dose-relevant data from 663,417 abdomen-pelvis and chest CT scans were obtained from 53 facilities. Patients were assigned arbitrary age cohorts with a minimum size of n=12 patients in each age group, for statistical purposes. All pediatric (<19 years old) cohorts at a given facility were compared to the adult cohort by a Kruskal-Wallis test for each of the four scan parameters - (1) x-ray tube kilovoltage (kV), (2) tube-current-by-exposure-time product (tube mAs), (3) scan pitch and (4) tube rotation time - to assess whether the distribution of values in the pediatric cohorts differed from the adult cohort. The same was repeated with volume CT dose index (CTDI_vol) and size-specific dose estimate (SSDE) to assess whether pediatric cohorts received less dose than adult cohorts. A P-value of <0.05 was deemed significant.

RESULTS

Across the 150 pediatric cohorts, 134 had scan parameters that were more child-sized than their adult counterparts. In 128 of these 134 pediatric cohorts, the CTDI_vol was less than the adult counterpart. In 111 of these 128 pediatric cohorts, the SSDE was less than the adult counterpart.

CONCLUSION

The study reaffirms that in practice, Image Gently's suggestions of lowering tube mAs and peak kilovoltage are commonly employed and effective at reducing pediatric CT dose.

Radiation use in diagnostic imaging in children: approaching the value of the pediatric radiology community

Medical imaging is foundational in the care of children, and much of the medical imaging province depends on ionizing radiation: radiography, fluoroscopy, CT and nuclear imaging. Many considerations for this imaging in children are distinct in the domains of appropriate radiation use, other factors that determine examination quality, the opportunities to engage and educate through networking, and the translation of research efforts. Given these needs, it is worth approaching the contributions and their impact by the pediatric radiology community, especially to the enhancement of this value in the care of children.

PEDIATRIC REGIONAL DRL ASSESSMENT IN COMMON CT EXAMINATIONS FOR MEDICAL EXPOSURE OPTIMIZATION IN TEHRAN, IRAN

The main purpose of this pilot study was to assess the regional diagnostic reference level (RDRL) of computed tomography (CT) examinations to optimise medical exposure in five pediatric medical imaging centers in Tehran, Iran where the most frequent CT examinations were investigated. For each patient, CT volume dose indexes (CTDIvol) and dose length product (DLP) in each group were recorded and their third quartile was calculated and set as RDRL. Pediatrics were divided into four age groups (<1; 1-5; 5-10 and 10-15 years). Then, the third quartile values for head, chest and abdomen-pelvic CTs were, respectively, calculated for each group in terms of CTDIvol: 21.3, 24.4, 24.2 and 36.3 mGy; 2.9, 3.2, 3.7 and 5.7 mGy; 3.7, 5.7, 6.3 and 6.8 mGy; and in terms of DLP: 322.2, 390.1, 424.9 and 694.1 mGy.cm; 53.1, 115.2, 145.3 and 167.6 mGy.cm and 128.7, 317.7, 460.2 and 813.8 mGy.cm. Finally, RDRLs were compared with other countries and preceding data in Iran. As a result, CTDIVOL values were lower than other national and international studies except for chest and abdomen-pelvic values obtained in Europe. Moreover, this matter applied to DLP so that other formerly reported values were higher than the present study but European values for chest and abdomen-pelvic scans and also Tehran studies conducted in 2012. Variation of scan parameters (tube voltage (kVp), tube current (mAs) and scan length), CTDIvol and DLP of different procedures among different age groups were statistically significant (P-value < 0.05). The variations in dose between CT departments as well as between identical scanners suggest a large potential for optimization of examinations relative to which this study provides helpful data.

To What Extent the Emergency Physicians in Riyadh City Are Aware of Patient Radiation Exposure From Diagnostic Imaging Requested in the Emergency Department

Introduction

Radiological imaging that uses ionizing radiation in emergency departments (EDs) has increased with advances in radiological diagnostic methods. Emergency (ER) physicians’ awareness of the radiation doses and the associated cancer risks that the patients are exposed to was surveyed using a questionnaire.

Aims

To assess the ER physicians’ awareness of radiation doses associated with the diagnostic imaging and to describe their practice about discussing radiation risk with patients at different hospitals in Riyadh city, Saudi Arabia.

Methods

A prospective, questionnaire-based observational study was conducted in 2016 among 176 ER physicians at different hospitals in Riyadh city. The percentage knowledge score and the frequency of discussing radiation risk with patients based on responses to three scenarios were rated on a visual analog scale (VAS), where a score of 100 indicated that physicians would always discuss it.

Results

The overall mean knowledge score was 28% (95% CI: 22-34). None of the studied parameters (gender, experience, country of medical qualification, type of degree, and employment level) showed a significant correlation with the overall awareness of ED physicians about radiation exposure. Over three-quarters of physicians (77%) underestimated the lifetime risk of fatal cancer attributed to a single computed tomography (CT) scan of the abdomen. Majority of physicians (60%) reported never discussing radiation risk with patients. The frequency at which physicians were discussing radiation risk with patients varied greatly depending on the clinical scenario (mean VAS scores between 46 and 82).

Conclusions

ER physicians of different hospitals in Riyadh city had a varied knowledge about the radiation exposure risks, although overall the perception was inadequate. The physicians should receive education, and the diagnostic imaging request may need to include information on radiation doses and risks.

The Value of Low-dose Prospective Dual-energy Computed Tomography with Iodine Mapping in the Diagnosis of Gastric Cancer

OBJECTIVES

This study investigated the radiation dose and value of prospective dualenergy computed tomography (DECT) in the diagnosis of gastric cancer.

METHODS

Sixty patients scheduled for computed tomography (CT) for preoperative staging were divided into two groups. Thirty patients (Group A) underwent a single contrast-enhanced abdominal CT acquisition using a dual-source mode (100 kV/140 kV). Weighted average images of the two-kilovolt acquisitions and iodine maps were created. The remaining 30 patients underwent a standard CT scan (Group B). Two observers performed a blinded read of the images for gastric lesions, evaluating the image quality and recording effective dose.

RESULTS

During the blinded read, observers found 90% (27/30) of the cancers in both groups. The mean imaging quality scores were 2.1±0.9 for Group A, and 2.3±1.1 for Group B. The effective mean doses were 6.59±0.59 mSv and 25.86±0.44 mSv for Groups A and B, respectively. Compared with the control group (B), the imaging quality in the low-dose group decreased a little, but the radiation dose substantially decreased by 74.6%.

CONCLUSION

The new DECT technique is valuable for examining gastric cancer patients. The dualkV scan mode can substantially reduce radiation dose while preserving good diagnostic image quality.

Paediatric computed tomography and subsequent risk of leukaemia, intracranial malignancy and lymphoma: a nationwide population-based cohort study

Red bone marrow and brain tissue are highly radiosensitive in children. We investigate the relationship between childhood computed tomography (CT) exposure and leukaemia, intracranial malignancy and lymphoma. All participants in the study were aged less than 16 years. A total of 1,479 patients in the leukaemia group, 976 patients in the intracranial malignancy group and 301 patients in the lymphoma group were extracted from the Catastrophic Illness Certificate Database in Taiwan as the disease group. In total, 126,677 subjects were extracted from the Longitudinal Health Insurance Database 2010 of the Taiwan National Health Insurance Research Database as the non-disease group. The odds ratios (ORs) and 95% confidence intervals (CIs) for childhood CT exposure and times of childhood CT were estimated. Childhood CT exposure was correlated to the intracranial malignancy group in both one-year (OR = 1.95, 95% CI 1.40-2.71, p < 0.001) and two-year (OR = 1.56, 95% CI 1.04-2.33, p = 0.031) exclusion periods. The time of childhood CT was also correlated to intracranial malignancy in both one-year (OR = 1.69, 95% CI 1.34-2.13, p < 0.001) and two-year (OR = 1.55, 95% CI 1.17-2.04, p = 0.002) exclusion periods. The results indicated that childhood CT exposure was correlated with an increased risk of future intracranial malignancy.

Pediatric CT radiation exposure: where we were, and where we are now

Since the turn of the last millennium, the pediatric radiology community has blazed a patient-quality and safety trail in helping to effectively address the public and the news media's concerns about the implications of ionizing radiation from CT scanners in children. As such, this article (1) reviews the potential deleterious effects of ionizing radiation, (2) discusses why limiting radiation exposure in children is so important, (3) tells the history of pediatric CT radiation exposure concerns, (4) explains the interventions that took place to address these concerns and (5) touches on the current school of thought on pediatric CT dose reduction.

Radiation Dose for Pediatric CT: Comparison of Pediatric versus Adult Imaging Facilities

Background The American College of Radiology Dose Index Registry for CT enables evaluation of radiation dose as a function of patient characteristics and examination type. The hypothesis of this study was that academic pediatric CT facilities have optimized CT protocols that may result in a lower and less variable radiation dose in children. Materials and Methods A retrospective study of doses (mean patient age, 12 years; age range, 0-21 years) was performed by using data from the National Radiology Data Registry (year range, 2016-2017) (n = 239 622). Three examination types were evaluated: brain without contrast enhancement, chest without contrast enhancement, and abdomen-pelvis with intravenous contrast enhancement. Three dose indexes-volume CT dose index (CTDI_vol), size-specific dose estimate (SSDE), and dose-length product (DLP)-were analyzed by using six different size groups. The unequal variance t test and the F test were used to compare mean dose and variances, respectively, at academic pediatric facilities with those at other facility types for each size category. The Bonferroni-Holm correction factor was applied to account for the multiple comparisons. Results Pediatric radiation dose in academic pediatric facilities was significantly lower, with smaller variance for all brain, 42 of 54 (78%) chest, and 48 of 54 (89%) abdomen-pelvis examinations across all six size groups, three dose descriptors, and when compared with that at the other three facilities. For example, abdomen-pelvis SSDE for the 14.5-18-cm size group was 3.6, 5.4, 5.5, and 8.3 mGy, respectively, for academic pediatric, nonacademic pediatric, academic adult, and nonacademic adult facilities (SSDE mean and variance P < .001). Mean SSDE for the smallest patients in nonacademic adult facilities was 51% (6.1 vs 11.9 mGy) of the facility's adult dose. Conclusion Academic pediatric facilities use lower CT radiation dose with less variation than do nonacademic pediatric or adult facilities for all brain examinations and for the majority of chest and abdomen-pelvis examinations. © RSNA, 2019 See also the editorial by Strouse in this issue.

Multisection computed tomography: Results from a Chinese survey on radiation dose metrics

BACKGROUND

As multisection spiral computed tomography (MSCT) have been extensively used, it is important to consider the amounts of doses the patients are exposed during a computed tomography (CT) examination. The aim of the current study was to summarize MSCT doses in Chinese patients to establish the diagnostic reference levels (DRLs).

METHODS

Radiation dose metrics were retrospectively collected from 164,073 CT examinations via the Radimetrics Enterprise Platform. Radiation dose metrics (volume CT dose index [CTDIvol], dose-length product [DLP], effective dose [ED], and organ dose) and size-specific dose estimate (SSDE) were calculated for adults and children based on anatomic area and scanner type.

RESULTS

The median CTDIvol and DLP values were highest in the head at 51.7 mGy (interquartile range [IQR], 33.2-51.7 mGy) and 906.5 mGy·cm (IQR, 582.4-1068.2 mGy·cm) and lowest in the chest at 7.9 mGy (IQR, 7.9-10.3 mGy) and 284.8 mGy·cm (IQR, 249.0-412.6 mGy·cm), respectively. The median SSDE values of chest and pelvis were 12.1 mGy (IQR, 10.8-14.1 mGy) and 36.3 mGy (IQR, 34.0-38.9 mGy), respectively. EDs for children were similar to adults except for an increased 1.5-, 0.77-, and 1.7-fold in the chest, neck, and pelvis, respectively (p < 0.001). Furthermore, radiation doses tended to increase with increasing slice number and decrease when exposure reduction techniques were used.

CONCLUSION

Our findings provide a basis for the evaluation of CT radiation doses and evidence for establishment of DRLs in China.

Guidelines on nuclear medicine imaging in neuroblastoma

Nuclear medicine has a central role in the diagnosis, staging, response assessment and long-term follow-up of neuroblastoma, the most common solid extracranial tumour in children. These EANM guidelines include updated information on ¹²³I-mIBG, the most common study in nuclear medicine for the evaluation of neuroblastoma, and on PET/CT imaging with ¹⁸F-FDG, ¹⁸F-DOPA and ⁶⁸Ga-DOTA peptides. These PET/CT studies are increasingly employed in clinical practice. Indications, advantages and limitations are presented along with recommendations on study protocols, interpretation of findings and reporting results.

USEFULNESS OF SIZE-SPECIFIC DOSE ESTIMATES IN PEDIATRIC COMPUTED TOMOGRAPHY: REVALIDATION OF LARGE-SCALE PEDIATRIC CT DOSE SURVEY DATA IN JAPAN

The objective of this research is to calculate the organ equivalent dose and effective dose from the scanning conditions at 165 centers in Japan using computed tomography (CT) Dose software and compare the results with the CT dose index volume (CTDIvol), dose length product (DLP) and size-specific dose estimates (SSDE) to validate the usefulness of SSDE. The CTDIvol and DLP were significantly lower in infants than in children (p < 0.05). No significant differences were found in the bone marrow equivalent dose and effective dose for the torso between infants and children (p > 0.05), and the bone marrow equivalent dose and effective dose for the head were higher in infants than children (p < 0.05). No significant difference was found in SSDE for the torso between infants and children (p > 0.05). Organ equivalent and effective doses for head CT scans are higher in infants than in children (I/P ratio ≥ 1). The I/P ratios of CTDIvol and DLP for chest and abdominal CT scans are also higher in Japan than in other countries. CTDIvol and DLP are not accurate when used as a dose index, and SSDE was considered suitable for dose assessment of the torso. However, for head CT in infants, a further reduction in radiation exposure is required.

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.

Trends in CT Request and Related Outcomes in a Pediatric Emergency Department

OBJECTIVES

To study and to establish the overall trends of computed tomography (CT) use and associated outcomes in the pediatric emergency department (PED) at Royal Hospital, Oman, from 2010 to 2014.

METHODS

The hospital electronic medical record was retrospectively searched to find children (from birth to 12 years old) who had visited the PED and the number of CT requests between 1 January 2010 and 31 December 2014. The types of CT examinations ordered were analyzed according to anatomical location and were as follows; head, abdomen/pelvis, chest, cervical spine/neck, and others.

RESULTS

There were a total of 67 244 PED visits during the study period, 569 of which received 642 CT scans. There was a remarkable rise in CT uses per 1000 visits from 7 in 2010 to 12 in 2014. There was a 56% hike in CT requests from 87 in 2010 to 175 in 2014 while the number of pediatric emergency visits rose by about 28% from 11 721 to 15 052. Although head CT scans were the most common, cervical spine CT scans had the highest rate of increase (600%) followed by the chest (112%), head (54%) and abdomen (13%). There were no significant changes in other CT scan requests. The cost of CT scans increased from $18 096 to $36 400 during the study period, which increased the average PED cost by about $2 per visit. The average time between a CT being requested and then performed was 1.24 hours.

CONCLUSIONS

CT use in the pediatric emergency department has risen significantly at a rate that markedly exceeds the growth of emergency visits. This is associated with an increase in PED costs and longer waiting times.

Staged imaging pathway for the evaluation of pediatric appendicitis

PURPOSE

Despite significant radiation exposure involved with computed tomography (CT) in evaluation of pediatric appendicitis, its use is still widespread. The goal of this study was to assess the effect of a staged imaging pathway for appendicitis to significantly decrease CT use while maintaining diagnostic accuracy.

METHODS

Chart review was performed for patients evaluated for appendicitis over a 12-month period prior to and after pathway implementation.

RESULTS

There was a significant decrease in CT use as initial imaging after implementation of the pathway; 87.1-13.4 % for evaluations positive for appendicitis (decrease 84.6 %, p < 0.0001) and 82.6-9.2 % for evaluations negative for appendicitis (decrease 88.9 %, p < 0.0001). Use of CT during any point in the evaluation decreased from 91.7 to 25.1 % (decrease 72.6 %, p < 0.0001). The negative appendectomy rate was similar; 5.4 % prior, 4.9 % post (p = 0.955). The missed appendicitis rate did not statistically change; 1.1 % prior, 3.7 % post (p = 0.523). The perforation rate was not statistically altered; 6.5 % prior; 9.8 % post (p = 0.421). 350 less patients underwent CT during the year following the pathway.

CONCLUSIONS

The staged imaging pathway resulted in a marked decrease in children exposed to CT without compromising diagnostic accuracy.

Role of Computed Tomography in Pediatric Chest Conditions

CT is the preferred cross-sectional imaging modality for detailed evaluation of anatomy and pathology of the lung and tracheobronchial tree, and plays a complimentary role in the evaluation of certain chest wall, mediastinal, and cardiac abnormalities. The article provides an overview of indications and different types of CT chest, findings in common clinical conditions, and briefly touches upon the role of each team member in optimizing and thus reducing radiation dose.

A Toolkit for Pediatric CT Dose Reduction in Community Hospitals

Pediatric CT radiation dose optimization is a challenging process for pediatric-focused facilities and community hospitals alike. Ongoing experience and trial-and-error approaches to dose reduction in the large academic hospital setting may position these centers to help community hospitals that strive for CT quality improvement. We describe our hands-on approach in a pilot project to create a partnership between an academic medical center and a community hospital to develop a toolkit for implementing CT dose reduction. Our aims were to (1) assess the acceptability of an interactive educational program and electronic toolkit booklet, (2) conduct a limited test of the efficacy of the toolkit in promoting knowledge and readiness to change, and (3) assess the acceptability and practicality of a collaborative approach to implementing dose reduction protocols in community hospitals. In partnering with the community hospital, we found that they had size-specific radiation doses two to three times higher than those at our center. Survey results after a site visit with interactive educational presentations revealed an increase in knowledge, stronger opinions about the health risks of radiation from CT scans, and willingness and perceived ability to reduce pediatric CT doses.

Nanosized Ultrasound Enhanced-Contrast Agent for in Vivo Tumor Imaging via Intravenous Injection

To enhance the detection limit of ultrasound (US) imaging, ultrasound enhanced-contrast agents (UECAs) that can go preferentially to the target tissue such as a tumor and amplify the US signal have been developed. However, nanosized UECAs among various UECAs developed are very limited to clearly demonstrate proper ability for selective tumor detection by US imaging upon their intravenous injection. In this study, we prepared CaCO3 nanoparticles that were formed inside a flexible and biocompatible pluronic-based nanocarrier. This nanosized UECA was stable in serum-containing media and generated CO2, more preferentially at low pH; thus, it could be detected by US imaging. After intravenous injection into tumor-bearing mice, this nanosized UECA showed a significant US contrast enhancement at the tumor site in 1 h, in contrast to no change in the liver, followed by a rapid clearance from the body in 24 h. Therefore, the present nanosized UECA could be applied as an effective diagnostic modality for in vivo tumor imaging by ultrasonography.

Tracking of radiation exposure in pediatric stone patients: The time is now

BACKGROUND

Despite the increasing incidence of pediatric nephrolithiasis, there is little data quantifying the radiation exposure associated with treatment of this disease. In this study, pediatric patients with nephrolithiasis who were managed at a single institution were identified, and the average fluoroscopy time and estimated radiation exposure associated with their procedures were reported.

METHODS

Stone procedures performed on pediatric patients between 2005 and 2012 were retrospectively identified. Procedures were classified as primary ureteroscopy (URS), stent placement prior to ureteroscopy (SURS), percutaneous nephrolithotomy (PCNL), and bilateral ureteroscopy (BLURS). Patient demographic information, stone size, stone location, number of radiographic images, and fluoroscopy times were analyzed.

RESULTS

A total of 152 stone procedures were included in the final analysis (92 URS, 38 SURS, eight BLURS and 14 PCNL). Mean patient age at time of stone treatment was 15.94 ± 4.1 years. Median fluoroscopy times were 1.6 (IQR 0.8-2.4), 2.1 (IQR 1.6-3.0), 2.5 (IQR 2.0-2.9), and 11.7 (IQR 5.0-18.5) minutes for URS, SURS, BLURS and PCNL, respectively. There was a moderate correlation between stone size and fluoroscopy time (r = 0.33). When compared with ureteroscopic procedures, PCNL was associated with a significantly higher fluoroscopy time (11.7 vs 2.1 min, P < 0.001). The estimated median effective dose was 3 mSv for ureteroscopic procedures and 16.8 mSv for PCNL. In addition to radiation exposure during treatment, patients in this cohort were exposed to an average of one (IQR1-3) CT scan and three (IQR 1-8) abdominal X-rays. No new malignancies were identified during the limited follow-up period.

CONCLUSIONS

Radiation exposure during treatment of pediatric stone disease is not trivial, and is significantly greater when PCNL is performed. Given the recommended maximum effective dose of 50 mSv in any one year, urologists should closely monitor the amount of fluoroscopy used, and consider the potential for radiation exposure when choosing the operative approach. Prospective studies are currently underway to elucidate precise dose measurements and localize sites of radiation exposure in children during stone treatment.

Variation in Pediatric Cervical Spine Computed Tomography Radiation Dose Index

OBJECTIVES

The objective was to evaluate variation in the current estimated radiation dose index for pediatric cervical spine (c-spine) computed tomography (CT) examinations.

METHODS

This was a retrospective analysis of pediatric (age younger than 19 years) c-spine CT examinations from the American College of Radiology Dose Index Registry, July 2011 through December 2014. We used the volume CT dose index (CTDIvol) as the radiation dose estimate and used summary statistics to describe patient and hospital characteristics.

RESULTS

There were 12,218 pediatric CT c-spine examinations performed across 296 participating hospitals. Fifty-six percent were in male patients, and 79% were in children older than 10 years. Most hospitals (55%) were community hospitals without trauma designations, and the largest proportion of examinations (41%) were performed at these hospitals. The median CTDIvol was 15 mGy (interquartile range = 9 to 23 mGy) representing a more than 2.5-fold difference between the 25th and 75th percentiles. Pediatric hospitals (both trauma and nontrauma centers) delivered the lowest CTDIvol across all age groups and showed the least amount of variability in dose.

CONCLUSIONS

There is significant variation in the radiation dose index for pediatric c-spine CT examinations. Pediatric hospitals practice at lower CT dose estimates than other hospitals. Individual hospitals should examine their practices in an effort to ensure standardization and optimization of CT parameters to minimize radiation exposures to pediatric patients.

EPI-CT: design, challenges and epidemiological methods of an international study on cancer risk after paediatric and young adult CT

Computed tomography (CT) has great clinical utility and its usage has increased dramatically over the years. Concerns have been raised, however, about health impacts of ionising radiation exposure from CTs, particularly in children, who have a higher risk for some radiation induced diseases. Direct estimation of the health impact of these exposures is needed, but the conduct of epidemiological studies of paediatric CT populations poses a number of challenges which, if not addressed, could invalidate the results. The aim of the present paper is to review the main challenges of a study on the health impact of paediatric CTs and how the protocol of the European collaborative study EPI-CT, coordinated by the International Agency for Research on Cancer (IARC), is designed to address them. The study, based on a common protocol, is being conducted in Belgium, Denmark, France, Germany, the Netherlands, Norway, Spain, Sweden and the United Kingdom and it has recruited over one million patients suitable for long-term prospective follow-up. Cohort accrual relies on records of participating hospital radiology departments. Basic demographic information and technical data on the CT procedure needed to estimate organ doses are being abstracted and passive follow-up is being conducted by linkage to population-based cancer and mortality registries. The main issues which may affect the validity of study results include missing doses from other radiological procedures, missing CTs, confounding by CT indication and socioeconomic status and dose reconstruction. Sub-studies are underway to evaluate their potential impact. By focusing on the issues which challenge the validity of risk estimates from CT exposures, EPI-CT will be able to address limitations of previous CT studies, thus providing reliable estimates of risk of solid tumours and leukaemia from paediatric CT exposures and scientific bases for the optimisation of paediatric CT protocols and patient protection.

Hospital-level factors associated with use of pediatric radiation dose-reduction protocols for head CT: results from a national survey

OBJECTIVES

To examine hospital-level factors associated with the use of a dedicated pediatric dose-reduction protocol and protective shielding for head CT in a national sample of hospitals.

METHODS

A mixed-mode (online and paper) survey was administered to a stratified random sample of US community hospitals (N = 751). Respondents provided information on pediatric head CT scanning practices, including use of a dose-reduction protocol. Modified Poisson regression analyses describe the relative risk (RR) of not reporting the use of a pediatric dose-reduction protocol or protective shielding; multivariable analyses adjust for census region, trauma level, children's hospital status, and bed size.

RESULTS

Of hospitals that were contacted, 38 were ineligible (no CT scanner, hospital closed, do not scan infants), 1 refused, and 253 responded (35.5% response rate). Across all hospitals, 92.6% reported using a pediatric dose-reduction protocol. Modified Poisson regression showed that small hospitals (0-50 beds) were 20% less likely to report using a protocol than large hospitals (>150 beds) (RR: 0.80, 95% confidence interval [CI]: 0.65-0.99; adjusted for covariates). Teaching hospitals were more likely to report using a protocol (RR: 1.10, 95% CI: 1.02-1.19; adjusted for covariates). After adjusting for covariates, children's hospitals were significantly less likely to report using protective shielding than nonchildren's hospitals (RR: 0.64, 95% CI: 0.56-0.73), though this may be due to more advanced scanner type.

CONCLUSION

Results from this study provide guidance for tailored educational campaigns and quality improvement interventions to increase the adoption of pediatric dose-reduction efforts.

Toward Large-Scale Process Control to Enable Consistent CT Radiation Dose Optimization

OBJECTIVE

This article reviews the concepts of CT radiation dose optimization and process control, discusses how to achieve optimization and how to verify that it is consistently accomplished, and proposes strategies to move toward large-scale application.

CONCLUSION

CT dose optimization is achieved when the least amount of radiation necessary is used to achieve adequate image quality. The key to consistent optimization is minimization of unnecessary variation. This minimization is accomplished through local process control mechanisms.

Lower radiation exposure from body CT imaging for trauma at a dedicated pediatric hospital

PURPOSE

We compare radiation exposure from body CT imaging for blunt trauma performed at outside hospitals (OH) versus our children's hospital (CH).

METHODS

We performed a retrospective chart review of all children transferred to our facility for management of trauma after undergoing a body CT scan at an OH from June 2011 to August 2013. Radiation from OH images was compared to our CH by matching to age, gender, and nearest date. Radiation measures included dose length product (DLP), computed tomography dose index (CTDI), and size-specific dose estimate (SSDE).

RESULTS

Fifty-one children were transferred from 39 OH. Abdomen/pelvis and chest/abdomen/pelvis imaging was performed in 30 and 21 children, respectively. Demographics are shown in Table 1. Results are illustrated in Tables 2 and 3. Contrast was utilized in 45 (1 oral, 41 IV, 3 both) and 51 (49 IV, 2 both). CT scans were performed at OH and CH, respectively (P=0.03).

CONCLUSIONS

Children receive significantly less radiation exposure with body CT imaging for blunt trauma when performed at our dedicated CH. CT scans were significantly more likely to be ordered with appropriate contrast at our CH.

Variation in the documentation of findings in pediatric voiding cystourethrogram

BACKGROUND

Few standards exist for reporting results of voiding cystourethrogram (VCUG).

OBJECTIVE

To assess the variation in reporting of VCUG findings from different facilities using a standardized assessment tool.

MATERIALS AND METHODS

VCUG reports were evaluated for demographic, technical, anatomical and functional information. Reports were categorized by age, gender, indication and vesicouretal reflux (VUR) status. Institutions were classified as a free-standing pediatric hospital (n = 3), pediatric hospital within a hospital (n = 11), or non-pediatric facility (n = 24) and reports were classified as having been read by a pediatric radiologist or not. Each category of outside reports (n = 152) was randomly matched with a twice-larger group of Hospital A reports from the same category (n = 304). Multivariate linear regression was used to analyze the association between the primary outcome (percentage of items described in dictated VCUG report) and the type of radiologist and institution.

RESULTS

Of the 456 studies, 66% were in girls, 56% were in those <12 months old, and the indication was urinary tract infection (UTI) in 81%. The mean percentage of items reported was 67 ± 14% (74 ± 7% at free-standing pediatric hospitals, 61 ± 10% at pediatric hospitals within a hospital, and 48 ± 11% at non-pediatric facilities). In multivariate analysis, VCUG reports generated at non-pediatric facilities had 17% fewer items included (95% CI: 14.5-19.7%, P < 0.0001), and pediatric hospitals within a hospital had 9% fewer items included (5.9-12.5%, P < 0.0001) when compared to free-standing pediatric hospitals. Reports read by a pediatric radiologist had 12% more items included (9.1-15.3%, P < 0.0001) compared to those read by a non-pediatric radiologist.

CONCLUSION

More complete VCUG reports were observed when generated at free-standing pediatric hospitals and when interpreted by a pediatric radiologist.

Boots on the ground: how to influence your local radiology departments to use appropriate CT dose

Most pediatric CT examinations (as many as 85%) are performed at non-pediatric-focused facilities. In contrast to children's hospitals and pediatric emergency departments, the number of CT examinations is increasing at these non-pediatric facilities. Compliance with diagnostic reference levels (DRLs) for dose has been shown to be poor at several metropolitan centers. Several high-yield interventions are worth exploring in an effort to achieve more optimal imaging care of children, such as electronic transfer of images to prevent duplication of examinations as well as personal feedback to referring institutions on dose, indications and quality by the pediatric referral center.

γ-H2AX foci are increased in lymphocytes in vivo in young children 1 h after very low-dose X-irradiation: a pilot study

BACKGROUND

Computed tomography (CT) is an imaging modality involving ionizing radiation. The presence of γ-H2AX foci after low to moderate ionizing radiation exposure has been demonstrated; however it is unknown whether very low ionizing radiation exposure doses from CT exams can induce γ-H2AX formation in vivo in young children.

OBJECTIVE

To test whether very low ionizing radiation doses from CT exams can induce lymphocytic γ-H2AX foci (phosphorylated histones used as a marker of DNA damage) formation in vivo in young children.

MATERIALS AND METHODS

Parents of participating children signed a consent form. Blood samples from three children (ages 3-21 months) undergoing CT exams involving very low blood ionizing radiation exposure doses (blood doses of 0.22-1.22 mGy) were collected immediately before and 1 h post CT exams. Isolated lymphocytes were quantified for γ-H2AX foci by a technician blinded to the radiation status and dose of the patients. Paired t-tests and regression analyses were performed with significance levels set at P < 0.05.

RESULTS

We observed a dose-dependent increase in γ-H2AX foci post-CT exams (P = 0.046) among the three children. Ionizing radiation exposure doses led to a linear increase of foci per cell in post-CT samples (102% between lowest and highest dose).

CONCLUSION

We found a significant induction of γ-H2AX foci in lymphocytes from post-CT samples of three very young children. When possible, CT exams should be limited or avoided by possibly applying non-ionizing radiation exposure techniques such as US or MRI.

Developing patient-specific dose protocols for a CT scanner and exam using diagnostic reference levels

The management of image quality and radiation dose during pediatric CT scanning is dependent on how well one manages the radiographic techniques as a function of the type of exam, type of CT scanner, and patient size. The CT scanner's display of expected CT dose index volume (CTDIvol) after the projection scan provides the operator with a powerful tool prior to the patient scan to identify and manage appropriate CT techniques, provided the department has established appropriate diagnostic reference levels (DRLs). This paper provides a step-by-step process that allows the development of DRLs as a function of type of exam, of actual patient size and of the individual radiation output of each CT scanner in a department. Abdomen, pelvis, thorax and head scans are addressed. Patient sizes from newborns to large adults are discussed. The method addresses every CT scanner regardless of vendor, model or vintage. We cover adjustments to techniques to manage the impact of iterative reconstruction and provide a method to handle all available voltages other than 120 kV. This level of management of CT techniques is necessary to properly monitor radiation dose and image quality during pediatric CT scans.