The Utility of Computed Tomography as a Screening Tool for the Evaluation of Pediatric Blunt Chest Trauma

Use of Chest Computed Tomography for Blunt Pediatric Chest Trauma: Does It Change Clinical Course?

INTRODUCTION

Given the concern for radiation-induced malignancy in children and the fact that risk of severe chest injury in children is low, the risk/benefit ratio must be considered in each child when ordering a computed tomography (CT) scan after blunt chest trauma.

METHODS

The study included pediatric blunt trauma patients (age, <15 years) with chest radiograph (CR) before chest CT on admission to our adult and pediatric level I trauma center. Surgeons were asked to view the blinded images and reads and indicate if they felt CT was warranted based on CR findings, if their clinical management change based on additional findings on chest CT, and how they might change management.

RESULTS

Of the 127 patients identified, 64.6% had no discrepancy between their initial CR and chest CT and 35.4% of the children's imaging contained a discrepancy. The majority of the pediatric and general trauma surgeons felt CT was indicated in 6 of 45 patients based on CR. In 87% of patients with a discrepancy in findings on CR and CT, the majority of surgeons agreed that their management would not change based on the additional information. In the 6 patients in which the CT was considered indicated, 4 of the 6 would have triggered a management change.

CONCLUSIONS

Our study suggests that chest CT scans frequently serve as confirmatory diagnostic tools and in the pediatric blunt chest trauma patient and can be withheld in many cases without hindering the management of an injured child.

Blunt traumatic scapular fractures are associated with great vessel injuries in children

BACKGROUND

Patients with stable blunt great vessel injury (GVI) can have poor outcomes if the injury is not identified early. With current pediatric trauma radiation reduction efforts, these injuries may be missed. As a known association between scapular fracture and GVI exists in adult blunt trauma patients, we examined whether that same association existed in pediatric blunt trauma patients.

METHODS

Bluntly injured patients younger than 18 years old were identified from 2012 to 2014 in the National Trauma Data Bank. Great vessel injury included all major thoracic vessels and carotid/jugular. Demographics of patients with and without scapular fracture were compared with descriptive statistics. The χ test was used to examine this association using SAS Version 9.4 (SAS Institute, Inc, Cary, NC).

RESULTS

We found a significant association between pediatric scapular fracture and GVI. Of 291,632 children identified, 1,960 had scapular fractures. Children with scapular fracture were 10 times more likely to have GVI (1.2%) compared to those without (0.12%, p < 0.0001). Most common GVI seen were carotid artery, thoracic aorta, and brachiocephalic or subclavian artery or vein. Children with both scapular fracture and GVI were most commonly injured by motor vehicles (57% collision, 26% struck).

CONCLUSIONS

Injured children with blunt scapular fracture have a 10-fold greater risk of having a GVI when compared to children without scapular fracture. Presence of blunt traumatic scapular fracture should have appropriate index of suspicion for a significant GVI in pediatric trauma patients.

LEVEL OF EVIDENCE

Epidemiologic and prognostic study, level III; Therapeutic, level IV.

Radiation Dose and Image Quality in Pediatric Neck CT

BACKGROUND AND PURPOSE

Optimization of pediatric neck CT protocols is of critical importance in order to maintain good diagnostic image quality while reducing the radiation burden. Our aim was to evaluate the image quality of pediatric neck CT studies before and after the implementation of a low radiation dose protocol.

MATERIALS AND METHODS

We retrospectively reviewed 179 pediatric neck CT studies, 75 before and 104 after the implementation of low-dose protocols, performed in children 0-16 years of age. The 2 cohorts were divided into 3 age groups, 0-4, 5-9, and 10-16 years. The signal-to-noise ratio was calculated using the axial image through the true vocal folds. Three neuroradiologists assessed the image quality of the same CT scan using a 5-point scoring system. We compared the CT dose index volume, dose-length product, image-quality ratings, and SNR of studies conducted at baseline and with low-dose protocols.

RESULTS

Image-quality ratings were lower in the low-dose than in the baseline cohort in children 10-16 years of age, but not in children 0-4 and 5-9 years of age. The SNR was lower in the low-dose cohort than in the baseline cohort in children 0-4 and 10-16 years of age, but not in children 5-9 years of age. Despite the decrease in image-quality scores in older children, 97% of the studies (73/75) in the baseline cohort and 96% of studies (100/104) in the low-dose cohort were considered of sufficient image quality.

CONCLUSIONS

Images acquired with the low-dose CT protocols were deemed to be of sufficient quality for making a clinical diagnosis. Our initial results suggest that there may be an opportunity for further radiation dose reduction without compromising diagnostic image quality using iterative reconstruction algorithms.

Predicting Thoracic Injury in Children With Multitrauma

OBJECTIVES

Previous pediatric trauma studies focused on predictors of abnormal chest radiographs or included patients with low injury severity. This study identified predictors of thoracic injury (TI) diagnoses in a high-risk population and determined TI rate without predictors.

METHODS

This study was a retrospective trauma registry analysis of previously healthy children aged 0 to 17 years with multisystem blunt trauma requiring trauma team activation and chest radiography who were divided into those with and without TI. Plausible TI predictors included Glasgow Coma Scale score of 13 or less, abnormal thoracic symptoms/signs, abnormal chest auscultation, respiratory distress/ rate higher than the 95th percentile, oxygen saturation less than 95%, abnormal abdominal signs/symptoms, tachycardia higher than the 95th percentile, blood pressure lower than the 5th percentile, and femur fracture.

RESULTS

One hundred forty-one (29%) of 493 eligible patients had TI. Independent TI predictors include thoracic symptoms/signs (odds ratio [OR], 6.0; 95% confidence interval [CI], 3.6-10.1), abnormal chest auscultation (OR, 3.5; 95% CI, 2.0-6.2), saturation less than 95% (OR, 3.1; 95% CI, 1.8-5.5), blood pressure lower than the 5th percentile (OR, 3.7; 95% CI, 1.1-12.2), and femur fracture (OR, 2.5; 95% CI, 1.2-5.4). Six (5%) of 119 children (95% CI, 0.01-0.09) without predictors had TI.

CONCLUSIONS

Predictors of TI include thoracic symptoms/signs, abnormal chest auscultation, saturation less than 95%, blood pressure lower than the 5th percentile, and femur fracture. Because an important portion of children without predictors had TI, chest radiography should remain part of pediatric trauma resuscitation.

RADIATION DOSE AND IMAGE QUALITY IN PEDIATRIC HEAD CT

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

Pediatric Cardiac Trauma in the United States: A Systematic Review

Literature discussing cardiac injuries in children is limited. Systematic search of PubMed identified 21 studies enrolling 1,062 pediatric patients who experienced cardiac trauma in the United States during the period 1961 to 2012. The predominant type of injury was blunt cardiac contusion affecting 59.7% (n = 634/1,062) of the study population. Motor vehicle crashes (53.5%, n = 391/731) were the leading cause of blunt cardiac trauma, while gunshot wounds (50%, n = 150/300) accounted for most penetrating injuries. Overall mortality rate was 35.2% (n = 374/1,062).

Review of Interventions and Radiation Exposure from Chest Computed Tomography in Children with Blunt Trauma

OBJECTIVE

To determine the radiation risk to a child undergoing trauma evaluation with chest computed tomography (CCT) for every clinically actionable injury identified.

STUDY DESIGN

This observational, cross-sectional study included all blunt trauma patients under 18 years of age undergoing CCT in a single urban emergency department. Via a retrospective chart review, therapeutic interventions done exclusively for chest injuries identified on CCT scan were identified. Effective radiation from each CCT was calculated and averaged and the dose required to diagnose 1 management-changing chest injury was determined.

RESULTS

Of 209 children undergoing CCT over a 19-month period, 168 were victims of blunt trauma. Ten required an intervention specifically for a chest injury identified on CCT (suggesting development of 1 malignancy per 37 actionable injures identified). None required an intervention for an injury exclusively noted on CCT, as all 10 actionable injuries were apparent via other modalities (radiograph, ultrasound examination, clinical examination).

CONCLUSION

Although 10 uniquely actionable injuries were identified on CCT, none were found only on CCT. Because CCTs rarely modified management, the amount of radiation administered per management change was sufficiently high to recommend reconsideration of current imaging practice in this single-center study.

Limiting thoracic CT: a rule for use during initial pediatric trauma evaluation

BACKGROUND

Despite increases in imaging guidelines for other body-regions during initial trauma assessment and the demonstrated utility of chest radiographs (CXR), guidelines for use of thoracic computed-tomography (TCT) are lacking. We hypothesized that TCT utilization had not decreased relative to other protocolized CTs, and mechanism and CXR could together predict significant injury independent of TCT.

METHODS

We performed a retrospective review of blunt trauma patients ≤18 y.o. (2007-2015) at two level-1 trauma centers who received chest imaging. Baseline characteristics and incidences of body region-specific CT were compared. Injury mechanism, intrathoracic pathology, and interventions among other data were examined (significance: p<0.05).

RESULTS

Although other body-region CT incidence decreased (p<0.05), TCT incidence did not change (p=0.65). Of the 2951 patients, 567 had both CXR and TCT, 933 received TCT-only, and 1451 had CXR-only. TCT altered management in 17 patients: 2 operations, 1 stent-placement, 1 medical management, 9 thoracostomy tube placements, and 4 negative diagnostic workups. All clinically significant changes were predicted by vehicle-related mechanism and abnormal CXR findings.

CONCLUSIONS

TCT utilization has not decreased over time. All meaningful interventions were predicted by CXR and mechanism of injury. We propose a rule, for prospective validation, reserving TCT for patients with abnormal CXR findings and severe vehicle-related trauma.

LEVEL OF EVIDENCE

Diagnostic study, Level III.

Predictors of Intrathoracic Injury after Blunt Torso Trauma in Children Presenting to an Emergency Department as Trauma Activations

BACKGROUND

Thoracic injuries are a major cause of death associated with blunt trauma in children. Screening for injury with chest x-ray study, compared with chest computed tomography (CT) scan, has been controversial, weighing the benefits of specificity with the detriment of radiation exposure.

OBJECTIVE

To identify predictors of thoracic injury in children presenting as trauma activations to a Level I trauma center after blunt torso trauma, and to compare these predictors with those previously reported in the literature.

METHODS

We performed a retrospective chart review of pediatric patients (<18 years of age) who presented to the Emergency Department of a Level I trauma center between June 2010 and June 2013 as a trauma activation after sustaining a blunt torso trauma and who received diagnostic imaging of the chest as part of their initial evaluation.

RESULTS

Data analysis was performed on 166 patients. There were 33 patients (20%) with 45 abnormalities detected on diagnostic imaging of the chest, with the most common abnormalities being lung contusion (36%), pneumothorax (22%), and rib fracture (13%). Statistically significant predictors of abnormal diagnostic imaging of the chest included Glasgow Coma Scale score (GCS) < 15 (27% with abnormality vs. 13% without abnormality), hypoxia (22% vs. 5%), syncope/loss of consciousness (55% vs. 35%), cervical spine tenderness (12% vs. 3%), thoraco-lumbar-sacral spine tenderness (41% vs. 17%), and abdominal/pelvic tenderness (12% vs. 3%).

CONCLUSIONS

Based on our data, predictors of thoracic injury in children after blunt torso trauma include GCS < 15, hypoxia, syncope/dizziness, cervical spine tenderness, thoraco-lumbar-sacral spine tenderness, and abdominal/pelvic tenderness.

Towards evidence-based emergency medicine: best BETs from the Manchester Royal Infirmary. BET: Is CT thorax necessary to exclude significant injury in paediatric patients with blunt chest trauma?

A shortcut review was carried out to establish if CXR had sufficient sensitivity to rule out significant thoracic injury in haemodynamically stable, paediatric patients with a significant mechanism of trauma. No studies were found that directly answered the three-part question, but 13 studies were found which were considered relevant. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these papers are tabulated. The clinical bottom line is that important thoracic injuries may not be clinically apparent and that CT scans have a significantly higher sensitivity than CXR in detecting such injuries.

Optimised paediatric CT dose at a tertiary children's hospital in Japan: a 4-y single-centre analysis

Since diagnostic reference levels (DRLs) for children are not currently established in Japan, the authors determined local DRLs for the full range of paediatric CT examinations in a single tertiary care children's hospital. A retrospective review of 4801 CT performance records for paediatric patients (<15 y old) who had undergone CT examinations from 2008 to 2011 was conducted. The most frequent examinations were of the head (52 %), followed by cardiac (15 %), temporal bone (9 %), abdomen (7 %), chest (6 %) and others (11 %). Approximately one-third of children received two or more CT scans. The authors' investigation showed that mean CTDIvol and DLP for head, chest and abdomen increased as a function of age. Benchmarking of the results showed that CTDIvol, DLP and effective dose for chest and abdomen examinations in this hospital were below average, whereas those for the head tended to be at or slightly above average of established DRL values from five countries. The results suggest that CT examinations as performed in a tertiary children's hospital in Japan are well optimised.

The effects of changes in utilization and technological advancements of cross-sectional imaging on radiologist workload

RATIONALE AND OBJECTIVES

To examine the effect of changes in utilization and advances in cross-sectional imaging on radiologists' workload.

MATERIALS AND METHODS

All computed tomography (CT) and magnetic resonance imaging (MRI) examinations performed at a single institution between 1999 and 2010 were identified and associated with the total number of images for each examination. Annual trends in institutional numbers of interpreted examinations and images were translated to changes in daily workload for the individual radiologist by normalizing to the number of dedicated daily CT and MRI work assignments, assuming a 255-day/8-hour work day schedule. Temporal changes in institutional and individual workload were assessed by Sen's slope analysis (Q = median slope) and Mann-Kendall test (Z = Z statistic).

RESULTS

From 1999 to 2010, a total of 1,517,149 cross-sectional imaging studies (CT = 994,471; MRI = 522,678) comprising 539,210,581 images (CT = 339,830,947; MRI = 199,379,634) were evaluated at our institution. Total annual cross-sectional studies steadily increased from 84,409 in 1999 to 147,336 in 2010, representing a twofold increase in workload (Q = 6465/year, Z = 4.2, P < .0001). Concomitantly, the number of annual departmental cross-sectional images interpreted increased from 9,294,140 in 1990 to 94,271,551 in 2010, representing a 10-fold increase (Q = 8707876/year, Z = 4.5, P < .0001). Adjusting for staffing changes, the number of images requiring interpretation per minute of every workday per staff radiologist increased from 2.9 in 1999 to 16.1 in 2010 (Q = 1.7/year, Z = 4.3, P < .0001).

CONCLUSIONS

Imaging volumes have grown at a disproportionate rate to imaging utilization increases at our institution. The average radiologist interpreting CT or MRI examinations must now interpret one image every 3-4 seconds in an 8-hour workday to meet workload demands.

Thyroid doses and risk to paediatric patients undergoing neck CT examinations

OBJECTIVE

To estimate thyroid doses and cancer risk for paediatric patients undergoing neck computed tomography (CT).

METHODS

We used average CTDI(vol) (mGy) values from 75 paediatric neck CT examinations to estimate thyroid dose in a mathematical anthropomorphic phantom (ImPACT Patient CT Dosimetry Calculator). Patient dose was estimated by modelling the neck as mass equivalent water cylinder. A patient size correction factor was obtained using published relative dose data as a function of water cylinder size. Additional correction factors included scan length and radiation intensity variation secondary to tube-current modulation.

RESULTS

The mean water cylinder diameter that modelled the neck was 14 ± 3.5 cm. The mathematical anthropomorphic phantom has a 16.5-cm neck, and for a constant CT exposure, would have thyroid doses that are 13-17% lower than the average paediatric patient. CTDI(vol) was independent of age and sex. The average thyroid doses were 31 ± 18 mGy (males) and 34 ± 15 mGy (females). Thyroid cancer incidence risk was highest for infant females (0.2%), lowest for teenage males (0.01%).

CONCLUSIONS

Estimated absorbed thyroid doses in paediatric neck CT did not significantly vary with age and gender. However, the corresponding thyroid cancer risk is determined by gender and age.

KEY POINTS

• Thyroid doses can be estimated from the CTDI(vol) in paediatric neck CT . • Scan length, neck size, and radiation intensity variation should be accounted for. • Estimated absorbed thyroid doses did not significantly vary with age and gender. • Thyroid cancer incidence risk is primarily determined by gender and age.

Nuking the radiation: minimizing radiation exposure in the evaluation of pediatric blunt trauma

PURPOSE OF REVIEW

Our objective is to highlight recent literature investigating low-radiation diagnostic strategies in the evaluation of pediatric trauma.

RECENT FINDINGS

In the area of minor head injury, research has focused on implementation of validated clinical decision rules into practice to reduce unnecessary computed tomography scans. Clinical observation may also serve as an adjunct to initial assessment and a potential substitute for computed tomography imaging. Subgroups of children with special needs or severe injury mechanisms may also be safely characterized by the clinical decision rule and spared radiation exposure. Physical examination techniques may be useful in diagnosing mandibular fractures. In addition, evidence suggests that plain radiography for evaluation of blunt thoracic trauma may be sufficient in many cases, and computed tomography could be reserved for those with abnormal radiographs, high-risk mechanisms, or abnormal physical findings. Clinical decision rules are able to predict intra-abdominal injury with high sensitivity. Data suggest that skeletal surveys may be modified to limit radiation exposure in the case of suspected nonaccidental trauma.

SUMMARY

More research is needed in development of pediatric-specific clinical decision rules and risk stratification and in testing low-radiation diagnostic modalities in the pediatric trauma population.

Acute Chest Diseases: Infection and Trauma

Acute chest diseases include clinical situations with infectious and traumatic etiology. Pulmonary infection is the most common indication for performing chest radiography. Radiological imaging often confirms the diagnosis and allows the evaluation of the location and extent of infection. Chest radiography is the primary imaging procedure and the starting point for the evaluation of all children with acute chest disease. Accurate interpretation of pediatric chest films also requires a basic understanding of the physiologic and anatomic differences among adults, neonates, and infants and their most important differences will be referred. Characterization of pulmonary infiltrates is important, because patterns of abnormality suggest specific organisms and aetiologies. Although providing evidence suggestive of the causative agent, the chest radiograph cannot confirm viral infection, confirm or exclude bacterial etiology. In fact, in infancy, pneumonia usually produces a combination of alterations of the airspace and interstitium. However, some aspects may be useful in distinguishing between viral and bacterial pneumonia. Close attention to CT technique is crucial for imaging evaluation of pneumonia in pediatric patients, namely those with persistent symptoms and/or progressive symptoms despite medical or surgical therapy, or in immunocompromised patients. CT with low radiation dose technique should be carefully performed in these cases. CT examination with IV contrast is very useful for the evaluation of complications of chest infection. Thoracic trauma in children is rare, only 4–6 % of children are hospitalized following severe trauma. Only a small number of children with trauma have thoracic injury (14 %), but the injuries tend to be of serious nature. About 25–50 % of thoracic trauma cases occur in combination with other trauma locations. Pulmonary contusion and lacerations, tracheobronchial injuries, pneumothorax, and esophageal rupture are referred as the main consequences of trauma. The decision for the appropriate use of imaging techniques must consider the specific case under review. Chest radiography should be the initial screening method. The decision to use CT is determined by the nature of the trauma, the clinical circumstances, and the prediction of future revaluation, always taking into account the radiation dose applied to the child.

CT use in hospitalized pediatric trauma patients: 15-year trends in a level I pediatric and adult trauma center

PURPOSE

To evaluate the 15-year trend in the use of computed tomography (CT) in hospitalized pediatric trauma patients admitted to Harborview Medical Center (HMC) from 1996 to 2010.

MATERIALS AND METHODS

This Health Insurance Portability and Accountability Act-compliant retrospective study was approved by the institutional review board. The requirement for informed consent was waived. The HMC trauma registry was linked to the billing department data, and patient and injury-related characteristics were extracted, in addition to type and frequency of CT procedures. Patients discharged from the emergency department and patients hospitalized for less than 24 hours were not included in this study. Patients were classified into three categories according to age: 0-14 years, 15-18 years, and 19-54 years (reference group). Multivariate negative binomial regression was used to compare CT usage among different age groups by adjusting for patient sex, race and/or ethnicity, insurance status, mechanism of injury, injury severity, final disposition (dead vs alive), and year of admission. The trend for CT use in children and teenagers was also evaluated.

RESULTS

A total of 64 425 trauma patients 0-54 years of age were admitted during the study period. Compared with CT usage in adults 19-54 years old, usage in children up to 15 years of age was significantly lower for spine (incidence rate ratio [IRR], 0.89; 95% confidence interval [CI]: 0.85, 0.92), maxillofacial (IRR, 0.89; 95% CI: 0.81, 0.97), and thoracic (IRR, 0.91; 95% CI: 0.84, 0.99) CT. Increased use of head CT was observed in children up to 15 years old (IRR, 1.09; 95% CI: 1.05, 1.13) and 15-18 years old (IRR, 1.08; 95% CI: 1.04, 1.13). From 2008 to 2010, usage rates in children up to 15 years old and 15-18 years old was relatively unchanged or slightly decreased for almost all CT types.

CONCLUSION

A decreasing or unchanged trend was observed in CT usage in hospitalized pediatric trauma patients in recent years. © RSNA, 2013.

CT Scans in Young People in Great Britain: Temporal and Descriptive Patterns, 1993-2002

Background. Although using computed tomography (CT) can be greatly beneficial, the associated relatively high radiation doses have led to growing concerns in relation to potential associations with risk of future cancer. Very little has been published regarding the trends of CT use in young people. Therefore, our objective was to assess temporal and other patterns in CT usage among patients aged under 22 years in Great Britain from 1993 to 2002. Methods. Electronic data were obtained from the Radiology Information Systems of 81 hospital trusts within Great Britain. All included patients were aged under 22 years and examined using CT between 1993 and 2002, with accessible radiology records. Results. The number of CT examinations doubled over the study period. While increases in numbers of recorded examinations were seen across all age groups, the greatest increases were in the older patients, most notably those aged 15-19 years of age. Sixty percent of CT examinations were of the head, with the percentages varying with calendar year and patient age. Conclusions. In contrast to previous data from the North of England, the doubling of CT use was not accompanied by an increase in numbers of multiple examinations to the same individual.

Pneumomediastinum in blunt trauma: A review

Pneumomediastinum (PM) is an uncommon finding after blunt trauma to the neck or chest. Motor vehicle collisions are the most common cause in adults, while falls are the most common in children. The majority of traumatic PM results from medial tracking of air from a concomitant pneumothorax. The Macklin effect, of air tracking medially along peribronchial sheaths from alveolar rupture, is responsible for most other cases. Chest pain is the most common symptom, and crepitus the most common sign. The majority of PM will resolve spontaneously, and requires no specific intervention. Only 1—6% of cases result from rupture of the larynx, trachea, bronchi or oesophagus. Hoarseness, dyspnea, persistent lung collapse or air leak should increase suspicion for aerodigestive injury. Computed tomography (CT) can help differentiate benign etiology from those that require surgical correction. High suspicion for aerodigestive injury based on clinical and/or CT findings should prompt diagnostic bronchoscopy and/or oesophagram.

CT scans in young people in Northern England: trends and patterns 1993-2002

BACKGROUND

Although CT can be greatly beneficial, its relatively high radiation doses have caused public health concerns.

OBJECTIVE

To assess patterns in CT usage among patients aged less than 22 years in Northern England during the period 1993-2002.

MATERIALS AND METHODS

Electronic data were obtained from radiology information systems of all nine National Health Service trusts in the region.

RESULTS

A total of 38,681 scans had been performed in 20,483 patients aged less than 22 years. The number of CT examinations rose, with the steepest increase between 1997 and 2000. The number of patients scanned per year increased less dramatically, with 2.24/1,000 population aged less than 22 years having one scan or more in 1993 compared to 3.54/1,000 in 2002. This reflects an increase in the median number of scans per patient, which rose from 1 in 1993 to 2 by 1999. More than 70% of CT examinations were of the head, with the number of head examinations varying with time and patient age.

CONCLUSION

The frequency of CT scans in this population more than doubled during the study period. This is partly, but not wholly, explained by an increase in the number of scans per patient.