Comparison of Different Methods of Calculating CT Radiation Effective Dose in Children
AMERICAN JOURNAL OF ROENTGENOLOGY
Newman, B., Ganguly, A., Kim, J., Robinson, T.
2012; 199 (2): W232-W239
Abstract
CT radiation dose is a subject of intense interest and concern, especially in children. Effective dose, a summation of whole-body exposure weighted by specific organ sensitivities, is most often used to compute and compare radiation dose; however, there is little standardization, and there are numerous different methods of calculating effective dose. This study compares five such methods in a group of children undergoing routine chest CT and explores their advantages and pitfalls.Patient data from 120 pediatric chest CT examinations were retrospectively used to calculate effective dose: two scanner dose-length product (DLP) methods using published sets of conversion factors by Shrimpton and Deak, the imaging performance and assessment of CT (ImPact) calculator method, the Alessio online calculator, and the Huda method.The Huda method mean effective dose (4.4 ± 2.2 mSv) and Alessio online calculator (5.2 ± 2.8 mSv) yielded higher mean numbers for effective dose than both DLP calculations (Shrimpton, 3.65 ± 1.8 mSv, and Deak, 3.2 ± 1.5 mSv) as well as the ImPact calculator effective dose (3.4 ± 1.7 mSv). Mean differences ranged from 10.2% ± 10.1% lower to 28% ± 37.3% higher than the Shrimpton method (used as the standard for comparison). Differences were more marked at 120 kVp than at 80 or 100 kVp and varied at different ages. Concordance coefficients relative to the Shrimpton DLP method were Deak DLP, 0.907; Alessio online calculator, 0.735; ImPact calculator, 0.926; and Huda, 0.777.Different methods of computing effective dose for pediatric CT produce varying results. The method used must be clearly described to allay confusion about documenting and communicating dose for archiving as well as comparative research purposes.
View details for DOI 10.2214/AJR.10.5895
View details for Web of Science ID 000306686200012
View details for PubMedID 22826426
Abstract
The aims of our study are to describe the incidence, clinical profile, and risk factors for pulmonary reperfusion injury after the unifocalization procedure for tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collateral arteries. We hypothesized the following: (1) Pulmonary reperfusion injury is more likely to occur after unifocalization procedures in which a septated circulation is not achieved, (2) pulmonary reperfusion injury is directly related to the severity of stenosis in major aortopulmonary collateral arteries, and (3) pulmonary reperfusion injury leads to longer intubation time and longer hospitalization.Consecutive patients with tetralogy of Fallot/pulmonary atresia/major aortopulmonary collateral arteries who underwent unifocalization procedures over a 5-year period were identified in our institutional database. Chest radiographs before the unifocalization procedure, from postoperative days 0 to 4, and from 2 weeks after the unifocalization procedure or at discharge were evaluated by a pediatric radiologist for localized pulmonary edema. Determination of stenosis severity was based on review of preoperative angiograms. Statistical analyses using multivariate repeated-measures analyses were performed with generalized estimating equations.Pulmonary reperfusion injury was present after 42 of 65 (65%) unifocalization procedures. In 36 of 42 cases of reperfusion injury, unilateral injury was present. Risk factors for the development of reperfusion injury included bilateral unifocalization (P = .01) and degree of stenosis (P = .03). We did not identify an association between pulmonary reperfusion injury and time to tracheal extubation or hospital discharge.Pulmonary reperfusion injury is common after the unifocalization procedure for tetralogy of Fallot/pulmonary atresia/major aortopulmonary collateral arteries. Severity of stenosis and bilateral unifocalization are associated with the development of reperfusion injury.
View details for DOI 10.1016/j.jtcvs.2011.12.030
View details for Web of Science ID 000305412200031
View details for PubMedID 22244564
Abstract
Contrast-enhanced cardiac MRA suffers from cardiac motion artifacts and often requires a breath-hold.This work develops and evaluates a blood pool contrast-enhanced combined respiratory- and ECG-triggered MRA method.An SPGR sequence was modified to enable combined cardiac and respiratory triggering on a 1.5-T scanner. Twenty-three consecutive children referred for pediatric heart disease receiving gadofosveset were recruited in HIPAA-compliant fashion with IRB approval and informed consent. Children underwent standard non-triggered contrast-enhanced MRA with or without suspended respiration. Additionally, a free-breathing-triggered MRA was acquired. Triggered and non-triggered studies were presented in blinded random order independently to two radiologists twice. Anatomical structure delineation was graded for each triggered and non-triggered acquisition and the visual quality on triggered MRA was compared directly to that on non-triggered MRA.Triggered images received higher scores from each radiologist for all anatomical structures on each of the two reading sessions (Wilcoxon rank sum test, P?
View details for DOI 10.1007/s00247-011-2196-y
View details for Web of Science ID 000297621800005
View details for PubMedID 21786125
Abstract
A major goal of imaging is to obtain the correct examination to answer the clinical questions with the lowest possible radiation exposure. While CT examination provides essential information in many cases, other modalities that do not entail ionizing radiation exposure may be appropriate substitutes either as an initial screening study or as an alternative to CT. US has become a valuable imaging tool in children encompassing many different clinical scenarios. This manuscript highlights some of the less well-accepted applications of US as the first imaging study in pediatric patients, especially in the emergency room environment. These include evaluation of suspected appendicitis, abdominal mass, pleural effusion/empyema, thymic abnormality vs. mediastinal mass and extremity soft-tissue mass or vessel patency. Adoption of US imaging as a problem-solving tool for issues such as these requires appropriate allocation of resources to ensure high-quality performance and interpretation of pediatric US studies around the clock.
View details for DOI 10.1007/s00247-011-2107-2
View details for PubMedID 21847738
Abstract
Pneumonia is an infection of the lung parenchyma caused by a wide variety of organisms in pediatric patients. The role of imaging is to detect the presence of pneumonia, and determine its location and extent, exclude other thoracic causes of respiratory symptoms, and show complications such as effusion/empyema and suppurative lung changes. The overarching goal of this article is to review cause, role of imaging, imaging techniques, and the spectrum of acute and chronic pneumonias in children. Pneumonia in the neonate and immunocompromised host is also discussed.
View details for DOI 10.1016/j.rcl.2011.06.007
View details for Web of Science ID 000295387500006
View details for PubMedID 21889014
Abstract
This manuscript reviews some of the more controversial dose-related issues in cardiac CT imaging. Discussion covers the relative merits of cardiac CT versus MR, advantages and concerns regarding gated versus nongated cardiac CT and advantages and concerns regarding the use of breast shields in girls undergoing cardiac CT imaging.
View details for DOI 10.1007/s00247-011-2153-9
View details for PubMedID 21847735
Abstract
This article presents an overview of the benign and malignant neoplasms that affect the chest in children and their imaging characteristics. The relative roles of plain film, fluoroscopy, ultrasound, CT, MR imaging, and nuclear imaging in assessing these lesions are reviewed. Areas covered include the mediastinum, heart, lungs, airway, pleura, and chest wall.
View details for DOI 10.1016/j.rcl.2011.05.010
View details for Web of Science ID 000294371900005
View details for PubMedID 21807166
Abstract
To evaluate the effectiveness of a staged ultrasonography (US) and computed tomography (CT) imaging protocol for the accurate diagnosis of suspected appendicitis in children and the opportunity for reducing the number of CT examinations and associated radiation exposure.This retrospective study was compliant with HIPAA, and a waiver of informed consent was approved by the institutional review board. This study is a review of all imaging studies obtained in children suspected of having appendicitis between 2003 and 2008 at a suburban pediatric emergency department. A multidisciplinary staged US and CT imaging protocol for the diagnosis of appendicitis was implemented in 2003. In the staged protocol, US was performed first in patients suspected of having appendicitis; follow-up CT was recommended when US findings were equivocal. Of 1228 pediatric patients who presented to the emergency department for suspected appendicitis, 631 (287 boys, 344 girls; age range, 2 months to 18 years; median age, 10 years) were compliant with the imaging pathway. The sensitivity, specificity, negative appendectomy rate (number of appendectomies with normal pathologic findings divided by the number of surgeries performed for suspected appendicitis), missed appendicitis rate, and number of CT examinations avoided by using the staged protocol were analyzed.The sensitivity and specificity of the staged protocol were 98.6% and 90.6%, respectively. The negative appendectomy rate was 8.1% (19 of 235 patients), and the missed appendicitis rate was less than 0.5% (one of 631 patients). CT was avoided in 333 of the 631 patients (53%) in whom the protocol was followed and in whom the US findings were definitive.A staged US and CT imaging protocol in which US is performed first in children suspected of having acute appendicitis is highly accurate and offers the opportunity to substantially reduce radiation.
View details for DOI 10.1148/radiol.10100984
View details for Web of Science ID 000288848800028
View details for PubMedID 21324843
Abstract
To address potential concern for cumulative radiation exposure with serial spiral chest computed tomography (CT) scans in children with chronic lung disease, we developed an approach to match bronchial airways on low-dose spiral and low-dose high-resolution CT (HRCT) chest images to allow serial comparisons. An automated algorithm matches the position and orientation of bronchial airways obtained from HRCT slices with those in the spiral CT scan. To validate this algorithm, we compared manual matching vs automatic matching of bronchial airways in three pediatric patients. The mean absolute percentage difference between the manually matched spiral CT airway and the index HRCT airways were 9.4 ± 8.5% for the internal diameter measurements, 6.0 ± 4.1% for the outer diameter measurements, and 10.1 ± 9.3% for the wall thickness measurements. The mean absolute percentage difference between the automatically matched spiral CT airway measurements and index HRCT airway measurements were 9.2 ± 8.6% for the inner diameter, 5.8 ± 4.5% for the outer diameter, and 9.9 ± 9.5% for the wall thickness. The overall difference between manual and automated methods was 2.1 ± 1.2%, which was significantly less than the interuser variability of 5.1 ± 4.6% (p<0.05). Tests of equivalence had p<0.05, demonstrating no significant difference between the two methods. The time required for matching was significantly reduced in the automated method (p<0.01) and was as accurate as manual matching, allowing efficient comparison of airways obtained on low-dose spiral CT imaging with low-dose HRCT scans.
View details for DOI 10.1007/s10278-009-9199-3
View details for Web of Science ID 000284163300011
View details for PubMedID 19756866
Abstract
Heterotaxy with polysplenia is associated with many cardiovascular anomalies including the occasional occurrence of congenital extrahepatic portosystemic shunts (CEPS). Missing this anomaly can lead to inappropriate and ineffective therapy.To emphasize the importance and associated anatomy of CEPS in conjunction with heterotaxy with polysplenia.Review of three young children who presented with cyanosis and pulmonary hypertension without a cardiac etiology. They were known (1) or discovered (2) to have heterotaxy with polysplenia.There was absence of the intrahepatic inferior vena cava (IVC) with azygos or hemiazygos continuation in all three cases. In spite of normal liver function, they were discovered to have large portosystemic shunts, splenorenal in location, along with diffuse peripheral pulmonary arterial dilatation suggestive of CEPS (Abernethy malformation) with hepatopulmonary or, more accurately, portopulmonary syndrome. All CEPS were ipsilateral to the spleens. Patency of the portal veins in these cases allowed for percutaneous shunt closure with resolution of cyanosis.CEPS is associated with heterotaxy with polysplenia and can be symptomatic because of pulmonary arteriovenous (AV) shunting. Portal and hepatic vein patency are critical for determining feasibility of CEPS closure.
View details for DOI 10.1007/s00247-009-1508-y
View details for Web of Science ID 000278582300007
View details for PubMedID 20069288
Abstract
In 1971, the Swedish radiologist Ulf Rudhe wrote a provocative paper on right middle lobe emphysema in infants with left-to-right shunts in which he suggested cardiac surgery rather than lung resection. At the time, this was counter to accepted medical practice. Earlier diagnosis and better medical management of ventricular septal defect in infants has proved Rudhe correct. However, two current cases of large left-to-right shunts in infants with emphysema of the right middle lobe prompt this historical review of what seemed a closed-episode in pediatric cardiac surgery.
View details for DOI 10.1007/s00247-009-1530-0
View details for Web of Science ID 000276149500016
View details for PubMedID 20135111
Abstract
The purpose of our study was to quantify the effect of changes made to the CT chest protocol on patient dose, image quality, and image noise when using a kilovoltage (kVp)-lowering strategy.We retrospectively selected 120 children who underwent chest CT: 60 in 2006 and 60 in 2008. In each group there were 30 children weighing less than 15 kg and 30 between 15 and 60 kg. In 2006 the CT protocol was 120 kVp and the reference current (mAs) was 65. In 2008, the kVp was 80 for < 15 kg and 100 for 15-60 kg, with reference mAs of 55. For each examination, the volume CT dose index (CTDI(vol)) and dose-length product (DLP) were recorded. Effective dose (ED) was estimated using the DLP method. Image noise was measured. Overall image quality was subjectively evaluated.For a weight < 15.0 kg, the CTDI(vol), DLP, and ED were reduced by 73%, 75%, and 73%, respectively (p < 0.05). For the weight range 15-60 kg, the CTDI(vol), DLP, and ED were reduced by 45%, 44%, and 48%, respectively (p < 0.05). Measured noise increased by 55% in the younger children and 41% in the older group (p < 0.05). All studies were considered diagnostically adequate.Significant radiation dose reduction can be achieved for routine pediatric chest CT by weight-based decreases in kVp in addition to low mAs. Increased noise was considered an acceptable trade-off for decreased dose, and image quality was acceptable.
View details for DOI 10.2214/AJR.09.3726
View details for Web of Science ID 000276906400005
View details for PubMedID 20410401
Abstract
Distinctive imaging findings are present when the left pulmonary artery (LPA) arises from the right pulmonary artery and forms a sling around the airway passing between airway and esophagus to reach the left lung. It is important to recognize the 2 distinct types of pulmonary sling. The less complex type I is associated with tracheobronchomalacia and is often managed successfully by LPA reimplantation. The more common and more complex type II is strongly associated with long segment tracheal stenosis. Appropriate management needs to address the airway abnormality in addition to the aberrant LPA. Both types, especially type II, are associated with cardiovascular, pulmonary, and other abnormalities that also need to be considered in therapeutic decisions. The role of imaging is to identify, define, and display the relevant anatomic relationships to facilitate appropriate management. Recent surgical advances have increased the likelihood of success of surgical correction of long segment airway stenosis.
View details for DOI 10.1053/j.sult.2010.01.004
View details for Web of Science ID 000276295500009
View details for PubMedID 20304323
Abstract
We report a case with initial misinterpretation of the radionuclide angiocardiographic study that was obtained in a child with persistent tachypnea and concern for residual left to right shunt after prior repair of total anomalous pulmonary veins and an atrial septal defect.Ultrasound, radionuclide angiocardiogram, and magnetic resonance imaging studies were obtained.The radionuclide study was ordered after an unremarkable ultrasound. Unsuspected severely reduced left pulmonary arterial flow associated with high-grade ipsilateral pulmonary venous obstruction led to misinterpretation of the radionuclide study as a large residual shunt. Later replotting of the graphic data using each lung separately corrected the error. Magnetic resonance played a key role in making the correct diagnosis.Significant asymmetric pulmonary flow due to vascular obstruction is an important additional potential pitfall to recognize in interpreting radionuclide angiocardiographic studies.
View details for Web of Science ID 000258941600001
View details for PubMedID 18645367
