Realization of Passive X-Ray Detection with a Low Detection Limit in Dion-Jacobson Halide Hybrid Perovskite

Halide hybrid perovskites are a kind of intriguing contenders for X-ray detection, and their low detection limits (LoDs) have played a crucial part in X-ray safety inspection and medical examination. However, there is still a significant challenge in manufacturing perovskite X-ray detectors with low LoDs. Herein, attributed to the bulk photovoltaic effect (BPVE) of a Dion-Jacobson (DJ) type 2D halide hybrid perovskite polar structure (3-methylaminopropylamine)PbBr4 (1), self-powered X-ray detection with low detection limit is successfully realized. Specifically, the crystal-based detector of 1 exhibits a low dark current at zero bias, which reduces the noise current (0.34 pA), leading to a low detection limit (58.3 nGyair s-1 ) which is two orders of magnitude lower than that of under external voltage bias. The combination of BPVE and LoDs of halide hybrid perovskite provides an efficient strategy to achieve passive X-ray detection with low doses.

Hematuria as a Sign of Kidney Stone Disease Evaluated Using Computed Tomography: A Review

Kidney stone is a common cause of acute pain in the abdomen in patients presenting to casualty. Being present in roughly 12% of the world's population makes it the most prevalent pathology of the urinary system. The ureters, kidneys, and bladder frequently develop calculi, resulting in hematuria. The most effective imaging technique for evaluating calculi is unenhanced helical computed tomography. The population, intervention, control, and outcomes (PICO)-formatted question was used to generate methodological medical subject heading (MeSH) phrases, which increased the search strategy's sensitivity in finding research. Some of these names ("hematuria") included "renal calculi" (MeSH) and "cone-beam computed tomography" (MeSH). Studies that satisfied these requirements were subjected to critical evaluation. The merits of the listed studies were evaluated using a unique quality assessment scale. The most accurate imaging diagnostic test for people with hematuria is multidetector computed tomography. If a patient over 40 presents with microscopic hematuria, a non-contrast computed tomography or ultrasound study should be performed, and if gross hematuria is observed, cystoscopy should be added. Pre- and post-contrast computed tomography scans and cystoscopy should be carried out on elderly patients.

Comparison of image quality between synthetic and patients' electrocardiogram-gated 320-row pediatric cardiac computed tomography

BACKGROUND

Pediatric cardiac computed tomography (CT) can be acquired without electrode placement by using synthetic electrocardiogram (ECG).

OBJECTIVE

To determine whether the depiction of gross cardiac structures and coronary arteries in 320-row pediatric CT is not inferior when CT is gated with synthetic ECG at 150 beats per minute (bpm), compared to the patients' own ECG.

MATERIALS AND METHODS

Sixty 320-row CT examinations performed in children younger than 3 years old with congenital cardiac anomaly were enrolled in this retrospective study. Thirty examinations were scanned using the children's own ECG for gating and 30 examinations were scanned using synthetic ECG at 150 bpm. The image quality was compared between the two gating modes using a 3-point scale to delineate the following anatomical structures: atrial septum, ventricular septum, right atrium, right ventricle, left atrium, left ventricle, main pulmonary artery, ascending aorta, aortic arch including the patent ductus arteriosus, descending aorta, right coronary artery and left main trunk. Beam-hardening artifacts from contrast enhancement material were evaluated using a 3-point scale, and the overall image quality was evaluated using a 5-point scale.

RESULTS

Synthetic ECG was not inferior to the patients' ECG in depicting each structure, beam-hardening artifact and overall image quality. Average indices were clinically acceptable imaging quality, except for subjective image quality of mid and distal coronary arteries.

CONCLUSION

Pediatric cardiac CT in patients younger than 3 years old can be acquired using synthetic ECG gating, with image quality not inferior to the patients' ECG.

Simple preoperative radiation safety interventions significantly lower radiation doses during central venous line placement in children

PURPOSE

The purpose of this study was to reduce radiation exposure during pediatric central venous line (CVL) placement by implementing a radiation safety process including a radiation safety briefing and a job-instruction model with a preradiation time-out.

METHODS

We reviewed records of all patients under 21 who underwent CVL placement in the operating room covering 22 months before the intervention through 10 months after 2013-2016. The intervention consisted of a radiation safety briefing by the surgeon to the intraoperative staff before each case and a radiation safety time-out. We measured and analyzed the dose area product (DAP), total radiation time pre- and postintervention, and the use of postprocedural chest radiograph.

RESULTS

100 patients with valid DAP measurements were identified for analysis (59 preintervention, 41 postintervention). Following implementation of the radiation safety process, there was a 79% decrease in median DAP (61.4 vs 13.1 rad*cm², P < 0.001) and a 73% decrease in the median radiation time (28 vs 7.6 s, P < 0.001). Additionally, there was a significant reduction in use of confirmatory CXR (95% vs 15%, P < 0.01).

CONCLUSION

A preoperative radiation safety briefing and a radiation safety time-out supported by a job-instruction model were effective in significantly lowering the absorbed doses of radiation in children undergoing CVL insertion.

TYPE OF STUDY

Case-control study.

LEVEL OF EVIDENCE

Level III.

Radiation dose management for pediatric cardiac computed tomography: a report from the Image Gently 'Have-A-Heart' campaign

Children with congenital or acquired heart disease can be exposed to relatively high lifetime cumulative doses of ionizing radiation from necessary medical imaging procedures including radiography, fluoroscopic procedures including diagnostic and interventional cardiac catheterizations, electrophysiology examinations, cardiac computed tomography (CT) studies, and nuclear cardiology examinations. Despite the clinical necessity of these imaging studies, the related ionizing radiation exposure could pose an increased lifetime attributable cancer risk. The Image Gently "Have-A-Heart" campaign is promoting the appropriate use of medical imaging studies in children with congenital or acquired heart disease while minimizing radiation exposure. The focus of this manuscript is to provide a comprehensive review of radiation dose management and CT performance in children with congenital or acquired heart disease.

Role of dual source multidetector row cardiac computed tomography angiography in diagnosis and management of congenital heart disease patients

Introduction

Primary evaluation of patients with congenital heart disease (CHD) traditionally relies on echocardiography and conventional cardiac angiography (CCA), both of which have potential limitations.

Aim

To test the hypothesis that cardiac computed tomography angiography (CCTA) is useful in the diagnosis and management of these patients.

Material and methods

The 3-year observational, analytical, retrospective, cohort study included a total of 111 tomographic studies of patients with congenital heart disease. Computed tomography scans were read twice and medical records were reviewed. The Aristotle complexity was assessed as well as and the contribution of new data in relation to clinical suspicion and diagnostic change was evaluated by two expert readers who were blinded for clinical outcome in consensus reading. The confidence interval was set at 95% and a p-value of < 0.05 was used as the cutoff for statistical significance.

Results

In total, 111 patients were included (56 men and 55 women) with a mean age of 7.2 years (1 day–71 years). The therapeutic procedure was performed without additional tests in 85.8% of patients. New findings were observed in 60.4% of patients and a subsequent change in management in 46.9%. New unexpected findings in CCTA prompted changes in management in 86.8% of patients. There were no significant differences in age between patients with new findings vs. patients without such findings in CCTA suggesting that CCTA-supported diagnosis of CHD is independent of age.

Conclusions

Use of dual-source cardiac computed tomography yields good diagnostic performance in congenital heart disease, prompts changes in management in more than one-third of patients, and reveals new findings in relation to the presumed diagnosis in most patients.

Projected cancer risks potentially related to past, current, and future practices in paediatric CT in the United Kingdom, 1990-2020

BACKGROUND

To project risks of developing cancer and the number of cases potentially induced by past, current, and future computed tomography (CT) scans performed in the United Kingdom in individuals aged <20 years.

METHODS

Organ doses were estimated from surveys of individual scan parameters and CT protocols used in the United Kingdom. Frequencies of scans were estimated from the NHS Diagnostic Imaging Dataset. Excess lifetime risks (ELRs) of radiation-related cancer were calculated as cumulative lifetime risks, accounting for survival probabilities, using the RadRAT risk assessment tool.

RESULTS

In 2000-2008, ELRs ranged from 0.3 to 1 per 1000 head scans and 1 to 5 per 1000 non-head scans. ELRs per scan were reduced by 50-70% in 2000-2008 compared with 1990-1995, subsequent to dose reduction over time. The 130 750 scans performed in 2015 in the United Kingdom were projected to induce 64 (90% uncertainty interval (UI): 38-113) future cancers. Current practices would lead to about 300 (90% UI: 230-680) future cancers induced by scans performed in 2016-2020.

CONCLUSIONS

Absolute excess risks from single exposures would be low compared with background risks, but even small increases in annual CT rates over the next years would substantially increase the number of potential subsequent cancers.

PAEDIATRIC CT EXPOSURE PRACTICE IN THE COUNTY OF RIO DE JANEIRO: THE NEED TO ESTABLISH DIAGNOSTIC REFERENCE LEVELS

A pilot study of dose indicators in paediatric computed tomography (CT) was conducted to prove the need to establish diagnostic reference levels (DRLs) for the county of Rio de Janeiro. The dose descriptors were estimated from the beam dosimetry by applying the protocols used in each examination. The total patient sample included 279 children. Regarding the comparison of the dose-length product values among the hospitals, the high-resolution chest CT scans were distinguished among the three types of examinations, due to the discrepancies of 1148 % (1-5 y age group) and 2248 % (5-10 y age group) presented in Hospital A's dose-length product values relative to Hospital D's dose-length product values. The results showed that without DRL, the dose variation can be significant between hospitals in the same county for the same age group in the same examination.

Computed tomography imaging in children with congenital heart disease: Indications and radiation dose optimization

Computed tomography (CT) technology is acquiring a key role in the diagnostic process of complex cardiac congenital anomalies. Recent advances and improvements in spatial and temporal resolution and radiation dose are encouraging the use of CT scanning in children. Paediatric cardiologists should have a good knowledge of the potential of CT techniques and their limitations to plan and properly perform CT examinations without forgetting radiation concerns. In this paper, we will discuss the principal indications for CT scans in newborns and children in our clinical practice. We will also outline the most-used strategies for dose reduction. Basic knowledge about the various CT techniques is crucial, not only to perform, but also to interpret CT results, thus helping the medical and surgical management of patients.

Cumulative radiation exposure and associated cancer risk estimates for scoliosis patients: Impact of repetitive full spine radiography

OBJECTIVE

To quantitatively evaluate the cumulative effective dose and associated cancer risk for scoliotic patients undergoing repetitive full spine radiography during their diagnosis and follow up periods.

METHODS

Organ absorbed doses of full spine exposed scoliotic patients at different age were computer simulated with the use of PCXMC software. Gender specific effective dose was then calculated with the ICRP-103 approach. Values of lifetime attributable cancer risk for patients exposed at different age were calculated for both patient genders and for Asian and Western population. Mathematical fitting for effective dose and for lifetime attributable cancer risk, as function of exposed age, was analytically obtained to quantitatively estimate patient cumulated effective dose and cancer risk.

RESULTS

The cumulative effective dose of full spine radiography with posteroanterior and lateral projection for patients exposed annually at age between 5 and 30 years using digital radiography system was calculated as 15mSv. The corresponding cumulative lifetime attributable cancer risk for Asian and Western population was calculated as 0.08-0.17%. Female scoliotic patients would be at a statistically significant higher cumulated cancer risk than male patients under the same full spine radiography protocol.

CONCLUSION

We demonstrate the use of computer simulation and analytic formula to quantitatively obtain the cumulated effective dose and cancer risk at any age of exposure, both of which are valuable information to medical personnel and patients' parents concern about radiation safety in repetitive full spine radiography.

Radiation dose reduction in paediatric coronary computed tomography: assessment of effective dose and image quality

OBJECTIVES

To assess the impact of different protocols on radiation dose and image quality for paediatric coronary computed tomography (cCT).

MATERIALS AND METHODS

From January-2012 to June-2014, 140 children who underwent cCT on a 64-slice scanner were included. Two consecutive changes in imaging protocols were performed: 1) the use of adaptive statistical iterative reconstruction (ASIR); 2) the optimization of acquisition parameters. Effective dose (ED) was calculated by conversion of the dose-length product. Image quality was assessed as excellent, good or with significant artefacts.

RESULTS

Patients were divided in three age groups: 0-4, 5-7 and 8-18 years. The use of ASIR combined to the adjustment of scan settings allowed a reduction in the median ED of 58 %, 82 % and 85 % in 0-4, 5-7 and 8-18 years group, respectively (7.3 ± 1.4 vs 3.1 ± 0.7 mSv, 5.5 ± 1.6 vs 1 ± 1.9 mSv and 5.3 ± 5.0 vs 0.8 ± 2.0 mSv, all p < 0,05). Prospective protocol was used in 51 % of children. The reduction in radiation dose was not associated with reduction in diagnostic image quality as assessed by the frequency of coronary segments with excellent or good image quality (88 %).

CONCLUSIONS

cCT can be obtained at very low radiation doses in children using ASIR, and prospective acquisition with optimized imaging parameters.

KEY POINTS

• Using ASIR allows 25 % to 41 % reduction in the ED. • Prospective protocol is used up to 51 % of children after premedication. • Low dose is possible using ASIR and optimized prospective paediatric cCT.

Giant coronary aneurysm caused by Kawasaki disease: consistency between catheter angiography and electrocardiogram gated dual-source computed tomography angiography

We present the case of a 5-year-old child with coronary complications due to Kawasaki disease; this patient unintentionally underwent both dual-source computed tomography (DSCT) coronary angiography and invasive coronary angiographic examination in 2 months. This case highlights the strong consistency of the results between DSCT coronary angiography and invasive coronary angiography. Compared to conventional invasive coronary angiography, DSCT coronary angiography offered additional advantages such as minimal invasiveness and less radiation exposure.

Usefulness of 64-detector computed tomography in the diagnosis and management of patients with congenital heart disease

INTRODUCTION AND OBJECTIVES

Although congenital heart defects are the most common major congenital abnormalities, the associated mortality has been decreasing due to improvements in their diagnosis and treatment. We assessed the usefulness of 64-multidetector computed tomography in the diagnosis and management of these patients.

METHODS

This 5-year observational, analytical, retrospective, cohort study included a total of 222 tomographic studies of patients with congenital heart disease. Computed tomography scans were read twice and medical records were reviewed. We assessed the complexity of the disease, patient, and radiological technique, and evaluated the contribution of new data in relation to clinical suspicion and diagnostic change. A confidence interval was set at 95% and a P value of<.05 was used as the cutoff for statistical significance.

RESULTS

In 35.1% of patients, the treatment procedure was performed after computed tomography without other tests. Additional diagnostic catheterization was performed in 12.5% of patients. There were new findings in 77% of patients (82.9% with complex disease), which prompted a change in patient management in 35.6%. All unexpected reports described new findings. No significant differences were found by age, sex, study period, urgency of the test order, patient complexity, or difficulty of the technique.

CONCLUSIONS

Use of 64-detector computed tomography yields good diagnostic performance in congenital heart disease, prompts changes in management in more than one-third of patients, and reveals new findings in relation to the presumed diagnosis in 77% of patients.

Risk of radiation-induced malignancies from CT scanning in children who underwent shunt treatment before 6 years of age: a retrospective cohort study with a minimum 10-year follow-up

OBJECT

A number of mathematical models predict the risk of future cancer from the ionizing radiation exposure of CT scanning. The predictions are alarming. Some models predict 29,000 future cancers and 14,500 deaths in the US will be directly caused by 1 year's worth of CT scanning. However, there are very few clinical data to justify or refute these claims. Young children are theoretically highly susceptible to the damaging effects of radiation. In this study, the authors examined children who underwent CSF shunt placement before 6 years of age. The authors chose to study shunt-treated patients with the assumption that these patients would undergo future imaging, facilitating surveillance. They chose a study period of 1991-2001 to allow more than 10 years of follow-up data.

METHODS

The authors studied 104 consecutive children who underwent CSF shunt placement prior to 6 years of age and who had at least 10 years of follow-up data. Sixty-two of these patients underwent shunt placement prior to 1 year of age. The age at the initial scanning session, the number of future CT scanning sessions, diagnosis, and results of any future studies were recorded. The age-specific radiation dose was calculated for children younger than 1 year. Children younger than 1 year at the time of shunt placement were evaluated separately, based on the assumption that they represented the highest risk cohort. The authors examined all data for any evidence of future leukemia or head/neck tumor (benign or malignant).

RESULTS

These children underwent a total of 1584 CT scanning sessions over a follow-up period of 1622 person-years. A total of 517 scanning sessions were performed prior to 6 years of age, including 260 in the 1st year of life. Children who underwent shunt placement before 1 year of age underwent an average of 16.3 ± 13.5 CT sessions (range 1-41). Children undergoing placement between 1 and 6 years of age received an average of 14.1 ± 12.5 CT studies (range 5-52). There were no subsequent tumors (benign or malignant) or leukemia detected.

CONCLUSIONS

Previously published models predict a significant number of future cancers directly caused by CT scanning. However, there are very few published clinical data. In the authors' study, zero future radiation-induced malignancies were detected after routine CT scanning in a high-risk group. While the authors do not consider their single-institution study adequate to define the actual risk, their data suggest that the overall risk is low. The authors hope this study encourages future collaborative efforts to define the actual risk to patients.

Entrance skin dosimetry and size-specific dose estimate from pediatric chest CTA

BACKGROUND

Size-specific dose estimate (SSDE), which corrects CT dose index (CTDI) for body diameter and is a better measure of organ dose than is CTDI, has not yet been validated in vivo.

OBJECTIVE

The purpose was to determine the correlation between SSDE and measured breast entrance skin dose (ESD) for pediatric chest CT angiography across a variety of techniques, scanner models, and patient sizes.

METHODS

During 42 examinations done on 4 different scanners over 7 years, we measured mid-sternal ESD as an approximation of breast dose with skin dosimeters. We recorded age, weight, effective tube current, kilovoltage potential, console CTDI, and dose-length product, from which we calculated effective dose. We measured effective chest diameter to convert CTDI to SSDE, and we correlated SSDE with measured ESD, using linear regression. We evaluated image quality to answer the clinical question.

RESULTS

Patient mean (±SD) age was 8.4 ± 6.1 years (median, 7.9 years; range, 0.02-19.5 years); mean weight was 35 ± 27 kg (median, 26 kg; range, 3.5-115 kg); effective chest diameter was 20 ± 7 cm (median, 19 cm; range, 10-35 cm). Mean effective dose was 2.9 ± 2.8 mSv (median, 2.2 mSv; range, 0.1-14.4 mSv). We observed a linear correlation (R(2) = 0.98, P < .005) between SSDE (mean, 11 ± 11mGy; median, 7 mGy; range, 0.5-40 mGy) and breast ESD (mean, 12 ± 11 mGy; median, 7 mGy; range, 0.3-44 mGy). Our doses, which compared favorably with those previously reported, decreased significantly (P < .05) during the course of our study, because of the introduction of automatic exposure control, low kilovoltage, and high pitch techniques. All studies were of diagnostic quality.

CONCLUSION

SSDE is a valid dose measure in children undergoing chest CT angiography over a wide range of scanner platforms, techniques, and patient sizes, and it may be used to model breast dose and to document the results of dose reduction strategies.

Coronary artery fistulas in children. Evaluation with 64-slice multidetector CT

OBJECTIVES

There are various types of coronary artery fistulas (CAF) with complex shapes. Therefore, it is important to make a correct diagnosis and to understand the relationship of the CAF to the adjacent structures before transcatheter occlusion or surgery. This study evaluated the feasibility of using 64-slice multidetector computed tomography (MDCT) angiography in diagnosing CAF.

METHODS

Two readers who were blinded to the results of echocardiography, intervention, or surgery retrospectively evaluated the coronary MDCT appearances of CAF in 10 patients (4 boys and 6 girls; mean age, 2.9 years; range, 1-6 years). The origin, course, and distal entry site of the fistula were determined. The diameters of the origin and the distal entry site were measured and compared with those seen during intervention or surgery.

RESULTS

The origin, course, and distal vessel entry site of the CAF were clearly outlined in all patients by MDCT. The distal vessel draining site involved a single entry vessel in all patients. Seven fistulas involved the right coronary artery, and three involved the left coronary artery. Four fistulas drained into the right ventricle, four into the right atrium, and two into the left ventricle. The diagnosis of CAF using MDCT was in accordance with diagnoses made during intervention or surgery. There was an excellent correlation between MDCT and transcatheter occlusion in quantifying the diameters of the origin and distal entry site (R = 0.90 and 0.92, respectively, P < 0.05).

CONCLUSION

Coronary 64-slice MDCT angiography depicted the whole shape and course of the CAF as well as of the surrounding structures. It may serve as a noninvasive diagnostic tool when planning a therapeutic strategy.

Computed tomographies and cancer risk in children: a literature overview of CT practices, risk estimations and an epidemiologic cohort study proposal

Radiation protection is a topic of great public concern and of many scientific investigations, because ionizing radiation is an established risk factor for leukaemia and many solid tumours. Exposure of the public to ionizing radiation includes exposure to background radiation, as well as medical and occupational exposures. A large fraction of the exposure from diagnostic procedures comes from medical imaging. Computed tomography (CT) is the major single contributor of diagnostic radiation exposure. An increase in the use of CTs has been reported over the last decades in many countries. Children have smaller bodies and lower shielding capacities, factors that affect the individual organ doses due to medical imaging. Several risk models have been applied to estimate the cancer burden caused by ionizing radiation from CT. All models predict higher risks for cancer among children exposed to CT as compared to adults. However, the cancer risk associated with CT has not been assessed directly in epidemiological studies. Here, plans are described to conduct an historical cohort study to investigate the cancer incidence in paediatric patients exposed to CT before the age of 15 in Germany. Patients will be recruited from radiology departments of several hospitals. Their individual exposure will be recorded, and time-dependent cumulative organ doses will be calculated. Follow-up for cancer incidence via the German Childhood Cancer Registry will allow computation of standardized incidence ratios using population-based incidence rates for childhood cancer. Dose-response modelling and analyses for subgroups of children based on the indication for and the result of the CT will be performed.

Cancer risk related to gastrointestinal diagnostic radiation exposure

Exposure to ionizing radiation is associated with an increased risk of cancer. With the growing use of diagnostic imaging studies, there is concern for increasing the risk of radiation associated malignancy of the gastrointestinal tract. The purpose of this review is to summarize the existing literature for risk of gastrointestinal malignancy after ionizing radiation exposure from diagnostic imaging studies. Estimates of organ specific effective doses of radiation vary widely based on the method of measurement and patient factors. Most of the current data are based on calculations of organ effective doses from anthropomorphic phantoms and estimated cancer risk based on radiation exposure from environmental sources. Radiation associated cancer risk is dependent on both the cumulative radiation dose and the radiosensitivity of the particular organ. The majority of radiation exposure and risk associated with gastrointestinal malignancy comes from CT scans, especially of the abdomen/pelvis. Of the abdominal organs, the colon carries the highest lifetime attributable risk of radiation associated malignancy. The attributable risk of malignancy for an individual diagnostic imaging study is low, but measurable, and therefore imaging studies without radiation such as MRI and ultrasound should be considered, especially in patients who require repeated imaging studies. There is a shortage of epidemiological data and an absence of prospective data with adequate follow-up to describe accurate risk estimates of gastrointestinal cancers after diagnostic imaging. More studies are needed to better determine the risks of malignancy from diagnostic imaging.

Evaluation of organ doses in CT examinations with an infant anthropomorphic phantom

The aim of this study is to evaluate organ doses in infant CT examinations with multi-detector row CT scanners. Radiation doses were measured with radiophotoluminescence glass dosemeters set in various organ positions within a 1-y-old child anthropomorphic phantom and organ doses were evaluated from the measurement values. Doses for tissues or organs within the scan range were 28-36 mGy in an infant head CT, 3-11 mGy in a chest CT, 5-11 mGy in an abdominal-pelvic CT and 2-14 mGy in a cardiac CT. The doses varied by the differences in the types of CT scanners and scan parameters used at each medical facility. Compared with those for children of various ages, the doses in an infant CT protocol were found to be similar to or slightly smaller than those in a paediatric CT for 5- or 6-y-old children.

Electronic decision support for diagnostic imaging in a primary care setting

METHODS

Clinical guideline adherence for diagnostic imaging (DI) and acceptance of electronic decision support in a rural community family practice clinic was assessed over 36 weeks. Physicians wrote 904 DI orders, 58% of which were addressed by the Canadian Association of Radiologists guidelines.

RESULTS

Of those orders with guidelines, 76% were ordered correctly; 24% were inappropriate or unnecessary resulting in a prompt from clinical decision support. Physicians followed suggestions from decision support to improve their DI order on 25% of the initially inappropriate orders. The use of decision support was not mandatory, and there were significant variations in use rate. Initially, 40% reported decision support disruptive in their work flow, which dropped to 16% as physicians gained experience with the software.

CONCLUSIONS

Physicians supported the concept of clinical decision support but were reluctant to change clinical habits to incorporate decision support into routine work flow.

Diagnostic application of multidetector-row computed tomographic coronary angiography to assess coronary abnormalities in pediatric patients: comparison with invasive coronary angiography

BACKGROUND

Multidetector-row computed tomographic (MDCT) coronary angiography has been validated for noninvasive assessment of coronary anatomy. However, we have less experience in diagnosing children with congenital or acquired coronary artery abnormalities by MDCT. We compared the results of MDCT with invasive coronary angiography (ICA) on identifying coronary abnormalities in infants, children, and adolescents with coronary artery abnormalities, including aneurysm, coronary fistula, or anomalous left coronary artery from pulmonary artery (ALCAPA).

METHODS

From January 2002 to December 2009, patients with congenital or acquired coronary abnormalities underwent either ICA, MDCT, or both studies for assessment of coronary anatomy. We reviewed all patients' clinical diagnosis, coronary abnormalities identified by MDCT or ICA, and analyzed the advantages and disadvantages between those two methods.

RESULTS

Thirty-three patients (20 males and 13 females) with a mean age of 10.3 years (range: 18 days to 25 years) had coronary abnormalities, including coronary artery aneurysm in Kawasaki disease (n=15), coronary artery fistula (n=12), myocardial bridge (n=2), and ALCAPA (n=4). In 17 patients only referred for ICA, 5 coronary aneurysms (3 on left main coronary artery, 1 on left anterior descending artery segment proximal, 1 on right coronary artery segment proximal), 11 coronary artery fistulas, and 2 ALCAPAs were detected. Sixteen patients received MDCT study, and 14 coronary artery aneurysms (4 on right coronary artery, 5 on left main coronary artery, 4 on left anterior descending artery, 1 on left circumflex artery), 3 myocardial bridges, 1 coronary artery fistulas, and 2 ALCAPAs were assessed. Ten patients with Kawasaki disease-related coronary lesions received MDCT study, and totally 102 (78.5%) segments permitted visualization with accurate diagnostic image quality. In this study, there were 11 patients with indication for conventional ICA spared invasive angiography after precise assessment by MDCT.

CONCLUSION

We conclude that MDCT is a good and useful modality for assessment of congenital or acquired coronary abnormalities in pediatric patients. However, MDCT cannot replace invasive cardiac catheterization and ICA because of lack of therapeutic role.

A review of patient dose and optimisation methods in adult and paediatric CT scanning

An increasing number of publications and international reports on computed tomography (CT) have addressed important issues on optimised imaging practice and patient dose. This is partially due to recent technological developments as well as to the striking rise in the number of CT scans being requested. CT imaging has extended its role to newer applications, such as cardiac CT, CT colonography, angiography and urology. The proportion of paediatric patients undergoing CT scans has also increased. The published scientific literature was reviewed to collect information regarding effective dose levels during the most common CT examinations in adults and paediatrics. Large dose variations were observed (up to 32-fold) with some individual sites exceeding the recommended dose reference levels, indicating a large potential to reduce dose. Current estimates on radiation-related cancer risks are alarming. CT doses account for about 70% of collective dose in the UK and are amongst the highest in diagnostic radiology, however the majority of physicians underestimate the risk, demonstrating a decreased level of awareness. Exposure parameters are not always adjusted appropriately to the clinical question or to patient size, especially for children. Dose reduction techniques, such as tube-current modulation, low-tube voltage protocols, prospective echocardiography-triggered coronary angiography and iterative reconstruction algorithms can substantially decrease doses. An overview of optimisation studies is provided. The justification principle is discussed along with tools that assist clinicians in the decision-making process. There is the potential to eliminate clinically non-indicated CT scans by replacing them with alternative examinations especially for children or patients receiving multiple CT scans.

The effect of heart rhythm on patient radiation dose with dual-source cardiac computed tomography

BACKGROUND

To lower the radiation exposure associated with cardiac CT, it is essential to identify all factors that influence radiation dose.

OBJECTIVES

We explored the effect of heart rhythm during scan acquisition on radiation dose with a 64-slice dual-source cardiac CT.

METHODS

Patient and scan data were collected prospectively in 302 consecutive patients referred for a clinical dual-source cardiac CT. Electrocardiograms recorded during acquisition were interpreted by a cardiologist and categorized as (1) normal sinus rhythm (NSR), (2) premature atrial contraction (PAC) or premature ventricular contraction (PVC), or (3) atrial fibrillation or flutter.

RESULTS

Of the 302 patients, 227 (75.2%) were in NSR and had no ectopy, 55 (18.2%) had PAC/PVC, and 20 (6.6%) had atrial fibrillation or flutter during the scan. Patients with irregular rhythm (PAC/PVC and atrial fibrillation or flutter) were older than patients with regular rhythm (61.0 vs 54.8 years; P = 0.006). Patients with NSR had the lowest estimated radiation dose, followed by PAC/PVC and atrial fibrillation/flutter (9.4, 14.5, 20.9 mSv; P < 0.001). The difference remained significant after adjustments for differences in examination type, tube current and voltage, scan length, pitch, and use of tube current modulation (9.8, 14.1, 17.9 mSv; P < 0.001). No significant association was observed between heart rhythm and subjective image quality although scans with regular rhythm and no ectopy had higher signal-to-noise and contrast-to-noise ratios (P < 0.01).

CONCLUSION

Compared to patients with NSR, patients with atrial fibrillation/flutter had the highest radiation exposure, followed by those with PAC/PVC. Even after adjustment for factors associated with radiation exposure, a significant difference in radiation dose persisted. These findings can be used to identify patients who are more likely to receive higher radiation dose when undergoing cardiac CT and to develop future more-efficient scanner algorithms for use in patients with arrhythmias.

Use of medical imaging procedures with ionizing radiation in children: a population-based study

OBJECTIVE

To determine population-based rates of the use of diagnostic imaging procedures with ionizing radiation in children, stratified by age and sex.

DESIGN

Retrospective cohort analysis.

SETTING

All settings using imaging procedures with ionizing radiation.

PATIENTS

Individuals younger than 18 years, alive, and continuously enrolled in UnitedHealthcare between January 1, 2005, and December 31, 2007, in 5 large US health care markets.

MAIN OUTCOME MEASURES

Number and type of diagnostic imaging procedures using ionizing radiation in children.

RESULTS

A total of 355 088 children were identified; 436 711 imaging procedures using ionizing radiation were performed in 150 930 patients (42.5%). The highest rates of use were in children older than 10 years, with frequent use in infants younger than 2 years as well. Plain radiography accounted for 84.7% of imaging procedures performed. Computed tomographic scans-associated with substantially higher doses of radiation-were commonly used, accounting for 11.9% of all procedures during the study period. Overall, 7.9% of children received at least 1 computed tomographic scan and 3.5% received 2 or more, with computed tomographic scans of the head being the most frequent.

CONCLUSIONS

Exposure to ionizing radiation from medical diagnostic imaging procedures may occur frequently among children. Efforts to optimize and ensure appropriate use of these procedures in the pediatric population should be encouraged.

Safety and efficacy of a drug regimen to control heart rate during 64-slice ECG-gated coronary CTA in children

BACKGROUND

The adult practice for ECG-gated single-source 64-slice coronary CTA (CCTA) includes administering beta-blockers to reduce heart rate. There are limited data on this process in children.

OBJECTIVE

To evaluate the safety and efficacy of a drug regimen to decrease heart rate before performing CCTA in children.

MATERIALS & METHODS

IV remifentanil and esmolol infusion were chosen to decrease heart rate in 41 children (mean age 6.5 years) while they were under general anesthesia (GA) for CCTA. Drug doses, changes in heart rate and procedural complications were recorded. CCTA image quality was graded on a scale of 1 to 5. The relationships between image quality and heart rate and image quality and age were evaluated. Patient effective radiation doses were calculated.

RESULTS

Heart rates were lowered utilizing esmolol (4 children), remifentanil (2 children) or both (35 children); 26 children received nitroglycerin for coronary vasodilation. The mean decrease in heart rate was 26%. There were no major complications. The average image-quality score was 4.4. Higher heart rates were associated with worse image quality (r = 0.67, P < 0.0001). Older age was associated with better image quality (r = 0.66, P < 0.0001). Effective radiation doses were 0.7 to 7.0 mSv.

CONCLUSION

Heart rate reduction for pediatric CCTA can be safely and effectively achieved while yielding high-quality images.

Coronary artery visibility in free-breathing young children with congenital heart disease on cardiac 64-slice CT: dual-source ECG-triggered sequential scan vs. single-source non-ECG-synchronized spiral scan

BACKGROUND

The potential impact of dual-source ECG-triggered sequential CT scan on coronary artery visibility has not been evaluated in free-breathing young children.

OBJECTIVE

To compare coronary artery visibility in free-breathing young children with congenital heart disease on cardiac 64-slice CT between dual-source ECG-triggered sequential (DSET) scan and single-source non-ECG-synchronized spiral (SSNE) scan.

MATERIALS AND METHODS

In 93 young children, 108 cardiac 64-slice CT examinations were performed during free-breathing. Visibility of coronary arteries and side branches was compared between SSNE and DSET scans. Heart rates and trigger delays for DSET scan were recorded. Effective dose of each scan technique was calculated.

RESULTS

Visual grades were significantly higher (P<0.001 or =0.011) on DSET scan than on SSNE scan except for the distal left anterior descending artery. Coronary arteries were traceable in 79.3% on DSET scan and 54.3% on SSNE scan in the overlapped scan range (P<0.0001), and 97.1% and 71.9% for the origins and proximal segments (P<0.0001). Visibility of side branches was improved on DSET scan by a factor of 2.0. Heart rates and trigger delays for DSET scan were 131±24 beats per min and 199±44 ms, respectively. Effective doses of DSET and SSNE scans were 0.36±0.12 mSv and 0.99±0.23 mSv, respectively.

CONCLUSION

DSET scan improves visibility of coronary arteries on cardiac 64-slice CT in free-breathing young children with congenital heart disease, compared with SSNE scan.

Radiation dose and cancer risk in retrospectively and prospectively ECG-gated coronary angiography using 64-slice multidetector CT

This study aimed to estimate the radiation dose and cancer risk to adults in England, the USA and Hong Kong associated with retrospectively and prospectively electrocardiogram (ECG)-gated coronary computed tomography angiography (CTA) using currently practised protocols in Hong Kong. The doses were simulated using the ImPACT spreadsheet. For retrospectively ECG-gated CTA with pitches of 0.2, 0.22 and 0.24, the effective doses were 27.7, 23.6 and 20.7 mSv, respectively, for males and 23.6, 20.0 and 18.8 mSv, respectively, for females. For prospectively ECG-gated CTA, the effective dose was 3.7 mSv for both males and females. A table of lifetime attributable risks (LAR) of cancer incidence was set up for the English population for the purpose of estimating cancer risk induced by low-dose radiation exposure, as previously reported for US and Hong Kong populations. From the tables, the LAR of cancer incidence for a representative 50-year-old subject was calculated for retrospectively ECG-gated CTA to be 0.112% and 0.227% for English males and females, respectively, 0.103% and 0.228% for US males and females, respectively, and was comparatively higher at 0.137% and 0.370% for Hong Kong males and females, respectively; for prospectively ECG-gated CTA, the corresponding values were calculated to be 0.014% and 0.035% for English males and females, respectively, and 0.013% and 0.036% for US males and females, respectively, and again were higher at 0.017% and 0.060% for Hong Kong males and females, respectively. Our study shows that prospectively ECG-gated CTA reduces radiation dose and cancer risks by up to 87% compared with retrospectively ECG-gated CTA.

Radiation dose and cancer risk from pediatric CT examinations on 64-slice CT: a phantom study

OBJECTIVE

To measure the radiation dose from CT scans in an anthropomorphic phantom using a 64-slice MDCT, and to estimate the associated cancer risk.

MATERIALS AND METHODS

Organ doses were measured with a 5-year-old phantom and thermoluminescent dosimeters. Four protocols; head CT, thorax CT, abdomen CT and pelvis CT were studied. Cancer risks, in the form of lifetime attributable risk (LAR) of cancer incidence, were estimated by linear extrapolation using the organ radiation doses and the LAR data.

RESULTS

The effective doses for head, thorax, abdomen and pelvis CT, were 0.7mSv, 3.5mSv, 3.0mSv, 1.3mSv respectively. The organs with the highest dose were; for head CT, salivary gland (22.33mGy); for thorax CT, breast (7.89mGy); for abdomen CT, colon (6.62mGy); for pelvis CT, bladder (4.28mGy). The corresponding LARs for boys and girls were 0.015-0.053% and 0.034-0.155% respectively. The organs with highest LARs were; for head CT, thyroid gland (0.003% for boys, 0.015% for girls); for thorax CT, lung for boys (0.014%) and breast for girls (0.069%); for abdomen CT, colon for boys (0.017%) and lung for girls (0.016%); for pelvis CT, bladder for both boys and girls (0.008%).

CONCLUSION

The effective doses from these common pediatric CT examinations ranged from 0.7mSv to 3.5mSv and the associated lifetime cancer risks were found to be up to 0.16%, with some organs of higher radiosensitivity including breast, thyroid gland, colon and lungs.