Cumulative radiation exposure and cancer risk estimates in emergency department patients undergoing repeat or multiple CT. AJR Am J Roentgenol. 2009;192:887-892. [PMID: 19304691 DOI: 10.2214/ajr.08.1351]

Significant but reasonable radiation exposure from computed tomography-related medical imaging in the ICU

Admission to an intensive care unit (ICU) is associated with increased medical imaging and radiation exposure, yet few studies have estimated the risk of cancer associated with these examinations. The purpose of this study was to review computed tomography (CT) scans performed on patients admitted to two urban academic ICUs, predict their radiation exposure, and calculate their estimated lifetime attributable risk of cancer (LAR). An electronic chart review was performed on all CT scans performed between January 2007 and December 2011. The estimated effective dose of radiation was calculated for each CT, and the LAR for each patient was predicted. Mean radiation exposure was 22.2 ± 25.0 mSv with a mean LAR of 0.1 ± 0.2 % and a median of 0.6 % with a range of <0.001 to 3.4 %. Our cohort received radiation doses higher than recommended by guidelines; however, the critical nature of their admission may have warranted these imaging studies. Estimated risk of cancer in this population was overall low.

Written Informed Consent for Computed Tomography of the Abdomen/Pelvis is Associated with Decreased CT Utilization in Low-Risk Emergency Department Patients

INTRODUCTION

The increasing rate of patient exposure to radiation from computerized tomography (CT) raises questions about appropriateness of utilization. There is no current standard to employ informed consent for CT (ICCT). Our study assessed the relationship between informed consent and CT utilization in emergency department (ED) patients.

METHODS

An observational multiphase before-after cohort study was completed from 4/2010-5/2011. We assessed CT utilization before and after (Time I/Time II) the implementation of an informed consent protocol. Adult patients were included if they presented with symptoms of abdominal/pelvic pathology or completed ED CT. We excluded patients with pregnancy, trauma, or altered mental status. Data on history, exam, diagnostics, and disposition were collected via standard abstraction tool. We generated a multivariate logistic model via stepwise regression, to assess CT utilization across risk groups. Logistic models, stratified by risk, were generated to include study phase and a propensity score that controlled for potential confounders of CT utilization.

RESULTS

7,684 patients met inclusion criteria. In PHASE 2, there was a 24% (95% CI [10-36%]) reduction in CT utilization in the low-risk patient group (p<0.002). ICCT did not affect CT utilization in the high-risk group (p=0.16). In low-risk patients, the propensity score was significant (p<0.001). There were no adverse events reported during the study period.

CONCLUSION

The implementation of ICCT was associated with reduced CT utilization in low-risk ED patients. ICCT has the potential to increase informed, shared decision making with patients, as well as to reduce the risks and cost associated with CT.

Reducing emergency CT radiation doses with simple techniques: A quality initiative project

INTRODUCTION

Use of indication-specific CT protocols and adjustment of scan parameters to decrease radiation exposure may result in significant dose reduction. We implemented these strategies and compare pre- and post-implementation radiation dose in emergency department (ED) patients.

METHOD

This was a descriptive, retrospective study. Patients older than 15 years who had undergone emergency CT examinations of the head, chest, abdomen, pelvis and abdominopelvic region in periods before and after dose-reduction implementation were included. The primary outcome was volume CT dose index (CTDIvol ) and dose length products (DLP).

RESULTS

There were 786 studies in the pre-implementation (group 1) and 955 studies in the post-implementation (group 2) periods. Radiation dose from all CT types significantly reduced in the post-implementation period. Average CTDIvol for head, chest, abdomen, pelvis and abdominopelvic region (doses during pre-implementation period in parentheses) were 51.5 (109), 8.1 (30.4), 13.1 (41.8), 11 (38), 11.2 (41.8) mGy, respectively. Average DLP was also significantly lower (pre-implementation dose in parentheses) in all CT types, which were 943 (2232), 324 (2517), 944 (5605), 280 (4024), 809 (7118) mGy●cm, respectively. Patients' age, gender, body mass index and size were not significantly different between the two groups. Image quality decreased but almost all examinations received an acceptable diagnostic subjective image quality.

CONCLUSION

Simple methods could help significantly reduce CT radiation exposure in ED patients while maintaining an acceptable level of diagnostic image quality.

The Utility of Computed Tomography in Shunted Patients with Idiopathic Intracranial Hypertension Presenting to the Emergency Department

BACKGROUND

Shunted patients with idiopathic intracranial hypertension (IIH) often present to the emergency department (ED) for symptoms related to their disease. Although brain imaging with computed tomography (CT) is often performed, particularly in the current medicolegal environment, its utility during these ED visits is unclear.

METHODS

The ED visits of all shunted adult patients with IIH from 2003-2015 were retrospectively reviewed. ED visits not related to IIH were excluded from our study.

RESULTS

Thirty-one patients visited the ED 171 times for IIH symptoms. Five patients had greater than 10 ED visits. Twenty-five (81%) patients had 131 visits involving a CT scan, while six (19%) patients were not scanned. The majority of scans (n = 126, 96%) showed no change; five (4%) scans detected new noncritical pathologies. On the basis of CT findings alone, treatment changes occurred in three (2.3%) instances. Of the 131 visits with a CT scan, twenty-five (19%) visits resulted in management changes; of the 40 ED visits without a CT scan, four (10%) visits resulted in a management change (P = 0.23).

CONCLUSIONS

In our cohort, CT imaging rarely showed a change in pathology or affected the management of patients with IIH. There was no difference in the rate of management changes between those patients who underwent a CT scan and those who did not. Given the risk of cumulative radiation exposure and cost of CT scans, CT imaging should be used when there is concern for visual dysfunction and the utility of CT imaging in the ED for the workup of other symptoms related to IIH must be explored further.

Age- and gender-specific estimates of cumulative CT dose over 5 years using real radiation dose tracking data in children

BACKGROUND

It is necessary to develop a mechanism to estimate and analyze cumulative radiation risks from multiple CT exams in various clinical scenarios in children.

OBJECTIVE

To identify major contributors to high cumulative CT dose estimates using actual dose-length product values collected for 5 years in children.

MATERIALS AND METHODS

Between August 2006 and July 2011 we reviewed 26,937 CT exams in 13,803 children. Among them, we included 931 children (median age 3.5 years, age range 0 days-15 years; M:F = 533:398) who had 5,339 CT exams. Each child underwent at least three CT scans and had accessible radiation dose reports. Dose-length product values were automatically extracted from DICOM files and we used recently updated conversion factors for age, gender, anatomical region and tube voltage to estimate CT radiation dose. We tracked the calculated CT dose estimates to obtain a 5-year cumulative value for each child. The study population was divided into three groups according to the cumulative CT dose estimates: high, ≥30 mSv; moderate, 10-30 mSv; and low, <10 mSv. We reviewed clinical data and CT protocols to identify major contributors to high and moderate cumulative CT dose estimates.

RESULTS

Median cumulative CT dose estimate was 5.4 mSv (range 0.5-71.1 mSv), and median number of CT scans was 4 (range 3-36). High cumulative CT dose estimates were most common in children with malignant tumors (57.9%, 11/19). High frequency of CT scans was attributed to high cumulative CT dose estimates in children with ventriculoperitoneal shunt (35 in 1 child) and malignant tumors (range 18-49). Moreover, high-dose CT protocols, such as multiphase abdomen CT (median 4.7 mSv) contributed to high cumulative CT dose estimates even in children with a low number of CT scans.

CONCLUSION

Disease group, number of CT scans, and high-dose CT protocols are major contributors to higher cumulative CT dose estimates in children.

Preoperative Mapping in Unicompartmental Knee Arthroplasty Using Computed Tomography Scans Is Associated with Radiation Exposure and Carries High Cost

Robotic-assisted knee arthroplasty with some systems requires the use of computed tomography (CT) scans. The associated radiation dose has not been studied. The effective dose (ED, mSv) of radiation was calculated for 236 preoperative CT scans used for planning of robotic assisted surgery. The mean ED was 4.8±3.0 mSv. There was a 3-fold difference in ED between institutions. One or more additional CT scans were obtained in 25% of patients, amounting to a cumulative ED per patient up to 103 mSv. Preoperative CT is a disadvantage of some robotic-assisted knee arthroplasty systems due to additional cost and radiation exposure. Newer image-free robotic technologies are an alternative to CT-dependent surgery if accuracy and safety are not compromised.

Optimizing diagnostic imaging in the emergency department

While emergency diagnostic imaging use has increased significantly, there is a lack of evidence for corresponding improvements in patient outcomes. Optimizing emergency department (ED) diagnostic imaging has the potential to improve the quality, safety, and outcomes of ED patients, but to date, there have not been any coordinated efforts to further our evidence-based knowledge in this area. The objective of this article is to discuss six aspects of diagnostic imaging to provide background information on the underlying framework for the 2015 Academic Emergency Medicine consensus conference, "Diagnostic Imaging in the Emergency Department: A Research Agenda to Optimize Utilization." The consensus conference aims to generate a high priority research agenda for emergency diagnostic imaging that will inform the design of future investigations. The six components herein will serve as the group topics for the conference: 1) patient-centered outcomes research; 2) clinical decision rules; 3) training, education, and competency; 4) knowledge translation and barriers to image optimization; 5) use of administrative data; and 6) comparative effectiveness research: alternatives to traditional CT use.

Estimating the lifetime risk of cancer associated with multiple CT scans

Multiple CT scans are often done on the same patient resulting in an increased risk of cancer. Prior publications have estimated risks on a population basis and often using an effective dose. Simply adding up the risks from single scans does not correctly account for the survival function. A methodology for estimating personal radiation risks attributed to multiple CT imaging using organ doses is presented in this article. The estimated magnitude of the attributable risk fraction for the possible development of radiation-induced cancer indicates the necessity for strong clinical justification when ordering multiple CT scans.

Depiction of branch vessels arising from intracranial aneurysm sacs: Time-of-flight MR angiography versus CT angiography

BACKGROUND

To evaluate the sensitivity, specificity, and accuracy of time-of-flight MR angiography (MRA) compared with CT angiography (CTA) for detection of branch vessels arising from the intracranial aneurysm sac, using a 3-tesla MR scanner and an area detector CT scanner.

METHODS

Fifty patients with an intracranial aneurysm (25 patients with a branch vessel arising from the sac and 25 patients without) underwent rotational intraarterial digital subtraction angiography (rotational DSA), MRA, and CTA. The following six image sets were assessed using a 3-point scale for the existence of a branch vessel: (1) volume rendering with MRA (MRA-VR); (2) CTA-VR; (3) source images with MRA; (4) source images with CTA; (5) VR and source images with MRA ('MRA-VR+source images'); and (6) 'CTA-VR+source images'. Each set comprised the data of all 50 patients. Three radiologists then performed consensus review and calculated the sensitivity, specificity, and accuracy for MRA and CTA; rotational DSA was considered as the gold standard.

RESULTS

Higher accuracies were obtained in review using VR+source compared with both VR and source alone. In addition, higher accuracies were obtained in review using MRA compared with CTA. The highest accuracy of 0.96 was obtained for 'MRA-VR+source images'; in contrast, accuracy on 'CTA-VR+source images' was 0.86.

CONCLUSIONS

The results show that 3-tesla MRA is an ideal non-invasive imaging examination for detection of a branch vessel arising from an intracranial aneurysm sac. Higher accuracy, especially sensitivity, with MRA compared with CTA was found in ICA, but accuracy with MRA was same as that with CTA in MCA.

Cumulative radiation exposure estimates of hospitalized patients from radiological imaging

PURPOSE

To examine the use of inpatient diagnostic imaging and image-guided procedures to estimate cumulative radiation exposure, radiation exposure based on imaging modality, and compare estimated doses based on patient demographics including age, gender, and diagnoses.

METHODS

Two hundred consecutive hospitalized adult patients who underwent diagnostic imaging studies at 2 large, affiliated hospitals were identified, and every study in each patient's electronic record that took place during a single hospitalization was reviewed. Dose estimates were calculated for each CT, fluoroscopy, nuclear medicine, plain film, and interventional radiology study or procedure based on reported dose length product, published reference values, and conversion factors. Medical records were reviewed to determine patient gender, age, diagnoses, length of stay, admitting service, and time in an intensive care unit (ICU).

RESULTS

Two hundred inpatients (46.5% male; mean age, 60.4 years) underwent 2,751 imaging studies (79.3% radiographs, 9.7% CT, 6.1% ultrasound, 2.5% interventional radiology, 2.2% MRI, 0.4% nuclear medicine). The mean dose estimate per patient was 14.8 milliSieverts (mSv) and the range was 0 mSv to 130.5 mSv. Mean cumulative dose estimates were significantly higher for patients whose hospitalizations included time in an ICU (17.9 mSv versus 11.3 mSv [P = .01]). CT examinations accounted for 82.1% of the total radiation dose estimate. Eleven patients (5.5%) received radiation dose estimates ≥ 50 mSv, including 2 ≥ 100 mSv.

CONCLUSIONS

Of imaged inpatients, 62% underwent at least 1 CT and the majority (82.1%) of inpatient radiation exposure was attributable to CT examinations. Mean dose estimate was 14.8 mSv per patient; 5.5% of patients experienced estimated doses ≥ 50 mSv.

The association between advanced diagnostic imaging and ED length of stay

OBJECTIVE

There has been a rise in advanced diagnostic imaging (ADI) use in the emergency department (ED). Increased utilization may contribute to longer length of stay (LOS), but prior reports have not considered improved methods for modeling skewed LOS data.

METHODS

The 2010 National Hospital Ambulatory Medical Care Survey data were analyzed by 5 common ED chief complaints. Generalized linear model (GLM) was compared to quantile and ordinary least squares (OLS) regression to evaluate the association between ADI and ED LOS. Receipt of computed tomography or magnetic resonance imaging was the primary exposure. Emergency department LOS was the primary outcome.

RESULTS

Of the 33,685 ED visits analyzed, 17% involved ADI. The median LOS for patients without ADI was 138 minutes compared to 252 minutes for those who received ADI. Overall, GLM offered the most unbiased estimates, although it provided similar adjusted point estimates to OLS for the marginal change in LOS associated with ADI. The effect of imaging differed by LOS quantile, especially for patients with abdominal pain, fever, and back symptoms.

CONCLUSIONS

Generalized linear model offered an improved modeling approach compared to OLS and quantile regression. Consideration of such techniques may facilitate a more complete view of the effect of ADI on ED LOS.

Familiarity with radiation exposure dose from diagnostic imaging for acute pulmonary embolism and current patterns of practice

OBJECTIVE

To assess the current level of knowledge and practice patterns of emergency physicians regarding radiation exposure from diagnostic imaging modalities for investigating acute pulmonary embolism (PE).

METHODS

An online survey was sent to adult emergency physicians working at two academic tertiary care adult emergency departments (EDs) to determine imaging choices for investigating PE in various patient populations and to assess their current knowledge of radiation doses and risks. A retrospective chart review was performed for all adult patients who underwent computed tomographic pulmonary angiography (CTPA) and/or ventilation-perfusion (V/Q) scanning in the same EDs.

RESULTS

The survey response rate was 72.1% (31 of 43 physicians). For patients < 30 years old, 83.9% of physicians chose V/Q scanning as their test of choice, regardless of gender. Although only a third of respondents knew the estimated radiation dose of a V/Q scan (37.5%) and a CTPA (32%), the majority were aware that V/Q scans involved less ionizing radiation than CTPAs. In the retrospective review, 663 charts were reviewed, including 201 CTPAs and 462 V/Q scans. V/Q scanning was the preferred modality in female patients (75.9% v. CTPA 24.1% [OR 2.1; 95% CI 1.5-2.9]) and in patients < 30 years old (87.9% v. CTPA 12.1% [OR 4.8; 95% CI 2.4-9.4]).

CONCLUSIONS

Although surveyed physicians possessed limited knowledge of radiation doses of CTPA and V/Q scans, they preferentially used the lower radiation V/Q scans in younger patients, particularly females, in both the survey vignettes and in clinical practice. This may reflect efforts to reduce radiation exposures at our institution.

Optimizing the balance between radiation dose and image quality in pediatric head CT: findings before and after intensive radiologic staff training

OBJECTIVE

The purpose of this study was to assess the radiation dose and image quality of pediatric head CT examinations before and after radiologic staff training.

MATERIALS AND METHODS

Outpatients 1 month to 14 years old underwent 215 unenhanced head CT examinations before and after intensive training of staff radiologists and technologists in optimization of CT technique. Patients were divided into three age groups (0-4, 5-9, and 10-14 years), and CT dose index, dose-length product, tube voltage, and tube current-rotation time product values before and after training were retrieved from the hospital PACS. Gray matter conspicuity and contrast-to-noise ratio before and after training were calculated, and subjective image quality in terms of artifacts, gray-white matter differentiation, noise, visualization of posterior fossa structures, and need for repeat CT examination was visually evaluated by three neuroradiologists.

RESULTS

The median CT dose index and dose-length product values were significantly lower after than before training in all age groups (27 mGy and 338 mGy ∙ cm vs 107 mGy and 1444 mGy ∙ cm in the 0- to 4-year-old group, 41 mGy and 483 mGy ∙ cm vs 68 mGy and 976 mGy ∙ cm in the 5- to 9-year-old group, and 51 mGy and 679 mGy ∙ cm vs 107 mGy and 1480 mGy ∙ cm in the 10- to 14-year-old group; p < 0.001). The tube voltage and tube current-time values after training were significantly lower than the levels before training (p < 0.001). Subjective posttraining image quality was not inferior to pretraining levels for any item except noise (p < 0.05), which, however, was never diagnostically unacceptable.

CONCLUSION

Radiologic staff training can be effective in reducing radiation dose while preserving diagnostic image quality in pediatric head CT examinations.

Emergency physicians' attitudes and preferences regarding computed tomography, radiation exposure, and imaging decision support

OBJECTIVES

Although computerized decision support for imaging is often recommended for optimizing computed tomography (CT) use, no studies have evaluated emergency physicians' (EPs') preferences regarding computerized decision support in the emergency department (ED). In this needs assessment, the authors sought to determine if EPs view overutilization as a problem, if they want decision support, and if so, the kinds of support they prefer.

METHODS

A 42-item, Web-based survey of EPs was developed and used to measure EPs' attitudes, preferences, and knowledge. Key contacts at local EDs sent letters describing the study to their physicians. Exploratory principal components analysis (PCA) was used to determine the underlying factor structure of multi-item scales, Cronbach's alpha was used to measure internal consistency of items on a scale, Spearman correlations were used to describe bivariate associations, and multivariable linear regression analysis was used to identify variables independently associated with physician interest in decision support.

RESULTS

Of 235 surveys sent, 155 (66%) EPs responded. Five factors emerged from the PCA. EPs felt that: 1) CT overutilization is a problem in the ED (α = 0.75); 2) a patient's cumulative CT study count affects decisions of whether and what type of imaging study to order only some of the time (α = 0.75); 3) knowledge that a patient has had prior CT imaging for the same indication makes EPs less likely to order a CT (α = 0.42); 4) concerns about malpractice, patient satisfaction, or insistence on CTs affect CT ordering decisions (α = 0.62); and 5) EPs want decision support before ordering CTs (α = 0.85). Performance on knowledge questions was poor, with only 18% to 39% correctly responding to each of the three multiple-choice items about effective radiation doses of chest radiograph and single-pass abdominopelvic CT, as well as estimated increased risk of cancer from a 10-mSv exposure. Although EPs wanted information on patients' cumulative exposures, they feel inadequately familiar with this information to make use of it clinically. If provided with patients' cumulative radiation exposures from CT, 87% of EPs said that they would use this information to discuss imaging options with their patients. In the multiple regression model, which included all variables associated with interest in decision support at p < 0.10 in bivariate tests, items independently associated with EPs' greater interest in all types of decision support proposed included lower total knowledge scores, greater frequency that cumulative CT study count affects EP's decision to order CTs, and greater agreement that overutilization of CT is a problem and that awareness of multiple prior CTs for a given indication affects CT ordering decisions.

CONCLUSIONS

Emergency physicians view overutilization of CT scans as a problem with potential for improvement in the ED and would like to have more information to discuss risks with their patients. EPs are interested in all types of imaging decision support proposed to help optimize imaging ordering in the ED and to reduce radiation to their patients. Findings reveal several opportunities that could potentially affect CT utilization.

Low-dose radiation from 18F-FDG PET does not increase cancer frequency or shorten latency but reduces kidney disease in cancer-prone Trp53+/- mice

There is considerable interest in the health effects associated with low-level radiation exposure from medical imaging procedures. Concerns in the medical community that increased radiation exposure from imaging procedures may increase cancer risk among patients are confounded by research showing that low-dose radiation exposure can extend lifespan by increasing the latency period of some types of cancer. The most commonly used radiopharmaceutical for positron emission tomography (PET) scans is 2-[(18)F] fluoro-2-deoxy-d-glucose ((18)F-FDG), which exposes tissue to a low-dose, mixed radiation quality: 634 keV β+ and 511 keV γ-rays. The goal of this research was to investigate how modification of cancer risk associated with exposure to low-dose ionising radiation in cancer-prone Trp53+/- mice is influenced by radiation quality from PET. At 7-8 weeks of age, Trp53+/- female mice were exposed to one of five treatments: 0 Gy, 10 mGy γ-rays, 10 mGy (18)F-FDG, 4 Gy γ-rays, 10 mGy (18)F-FDG + 4 Gy γ-rays (n > 185 per group). The large 4-Gy radiation dose significantly reduced the lifespan by shortening the latency period of cancer and significantly increasing the number of mice with malignancies, compared with unirradiated controls. The 10 mGy γ-rays and 10 mGy PET doses did not significantly modify the frequency or latency period of cancer relative to unirradiated mice. Similarly, the PET scan administered prior to a large 4-Gy dose did not significantly modify the latency or frequency of cancer relative to mice receiving a dose of only 4 Gy. The relative biological effectiveness of radiation quality from (18)F-FDG, with respect to malignancy, is approximately 1. However; when non-cancer endpoints were studied, it was found that the 10-mGy PET group had a significant reduction in kidney lesions (P < 0.021), indicating that a higher absorbed dose (20 ± 0.13 mGy), relative to the whole-body average, which occurs in specific tissues, may not be detrimental.

Abdominal computed tomography, colonography and radiation exposure: what the surgeon needs to know

AIM

Abdominal computed tomography (CT) improves the accuracy of clinical diagnosis and facilitates patient management. Radiation exposure must be considered by requesting clinicians and is especially relevant owing to the increasing use of CT colonography for diagnosis and screening of colorectal disorders. This review describes the radiation dose of abdominopelvic CT and colonography and attempts to quantify the risk for the clinician.

METHOD

Articles were searched in the PubMed and Medline databases using combinations of the MeSH terms 'radiation', 'abdominal computed tomography' and 'colonography'. Electronic English language abstracts were read by two reviewers and the full article was retrieved if relevant to the review.

RESULTS

Abdominopelvic CT and CT colonography convey significant radiation dose to the patient but also have considerable diagnostic potential. In the right clinical context, the radiation risk should not be overestimated. Techniques to reduce the dose should be used. Repeated imaging in certain patients is a concern and should be monitored.

CONCLUSION

Radiation risk can be quantified and presented simply in a manner that both patients and doctors can comprehend and evaluate. This approach will diminish misconceptions and allow a rational choice of diagnostic test.

Head CT scan overuse in frequently admitted medical patients

BACKGROUND

Patients frequently admitted to medical services undergo extensive computed tomography (CT) imaging. Some of this imaging may be unnecessary, and in particular, head CT scans may be over-used in this patient population. We describe the frequency of abnormal head CT scans in patients with multiple medical hospitalizations.

METHODS

We retrospectively reviewed all CT scans done in 130 patients with 7 or more admissions to medical services between January 1 and December 31, 2011 within an integrated health care system. We calculated the number of CT scans, anatomic site of imaging, and source of ordering (emergency department, inpatient floor). We scored all head CT scans on a 0-4 scale based on the severity of radiographic findings. Higher scores signified more clinically important findings.

RESULTS

There were 795 CT scans performed in total, with a mean of 6.7 (± SD 5.8) CT scans per patient. Abdominal/pelvis (39%), chest (30%), and head (22%) CT scans were the most frequently obtained. The mean number of head CT scans performed was 2.9 (SD ± 4.2). Inpatient floors were the major site of CT scan ordering (53.7%). Of 172 head CT scans, only 4% had clinically significant findings (scores of 3 or 4).

CONCLUSIONS

Patients with frequent medical admissions are medically complex and undergo multiple CT scans in a year. The vast majority of head CT scans lack clinically significant findings and should be ordered less frequently. Interdisciplinary measures should be advocated by hospitalists, emergency departments, and radiologists to decrease unnecessary imaging in this population.

Does health information exchange reduce redundant imaging? Evidence from emergency departments

BACKGROUND

Broad-based electronic health information exchange (HIE), in which patients' clinical data follow them between care delivery settings, is expected to produce large quality gains and cost savings. Although these benefits are assumed to result from reducing redundant care, there is limited supporting empirical evidence.

OBJECTIVE

To evaluate whether HIE adoption is associated with decreases in repeat imaging in emergency departments (EDs).

DATA SOURCE/STUDY SETTING

ED discharge data from the State Emergency Department Databases for California and Florida for 2007-2010 were merged with Health Information Management Systems Society data that report hospital HIE participation.

METHODS

Using regression with ED fixed effects and trends, we performed a retrospective analysis of the impact of HIE participation on repeat imaging, comparing 37 EDs that initiated HIE participation during the study period to 410 EDs that did not participate in HIE during the same period. Within 3 common types of imaging tests [computed tomography (CT), ultrasound, and chest x-ray), we defined a repeat image for a given patient as the same study in the same body region performed within 30 days at unaffiliated EDs.

RESULTS

In our sample there were 20,139 repeat CTs (representing 14.7% of those cases with CT in the index visit), 13,060 repeat ultrasounds (20.7% of ultrasound cases), and 29,703 repeat chest x-rays (19.5% of x-ray cases). HIE was associated with reduced probability of repeat ED imaging in all 3 modalities: -8.7 percentage points for CT [95% confidence interval (CI): -14.7, -2.7], -9.1 percentage points for ultrasound (95% CI: -17.2, -1.1), and -13.0 percentage points for chest x-ray (95% CI: -18.3, -7.7), reflecting reductions of 44%-67% relative to sample means.

CONCLUSIONS

HIE was associated with reduced repeat imaging in EDs. This study is among the first to find empirical support for this anticipated benefit of HIE.

Inpatient imaging utilization: trends of the past decade

OBJECTIVE

We have previously reported inpatient imaging utilization trends at our institution from fiscal year (FY) 1984 through FY 2002. In this study, we assessed the trends in imaging utilization for inpatients from FY 2003 through FY 2012.

MATERIALS AND METHODS

In this institutional review board-approved retrospective study performed at a 793-bed tertiary care academic institution, we reviewed imaging utilization in adult inpatients from October 1, 2002, through September 30, 2012 (FY 2003 through FY 2012), and recorded the gross number of imaging studies coded by modality (conventional [radiography and fluoroscopy], ultrasound, nuclear medicine, CT, and MRI) and associated relative value units (RVUs). We used linear regression to assess trends in number of imaging studies and RVUs per case-mix-adjusted admission (CMAA).

RESULTS

The total number of imaging studies, as well as the number of CT, nuclear medicine, and conventional studies adjusted for case mix, decreased (p=0.02, p=0.0006, p=0.0008, and p=0.001, respectively); CT per CMAA increased until FY 2009 and then decreased through FY 2012. Utilization of ultrasound and MRI did not change significantly (p=0.15 and p=0.22, respectively). Unadjusted global RVUs increased until FY 2009 and then showed a slight decrease through FY 2012 (p=0.04), whereas RVUs per CMAA did not change significantly (p=0.18).

CONCLUSION

After decades of continued rise, imaging utilization for inpatients significantly decreased by most measures between FY 2009 and FY 2012. Future studies to evaluate the contribution of various factors to this decline, including efforts to reduce inappropriate use of imaging and concerns about potential harms of radiation exposure, may be helpful in optimizing imaging utilization and resource planning.

The cumulative risk of multiple CT exposures using two different methods

The aim of this study was to compare the summing method (A) with the complement method (B) for calculating the cumulative lifetime-attributable-risk (LAR(tot)) of tumor incidence and mortality of multiple CT exposures. Method A defines LAR(tot) as the summation of the risk of each separate exposure. Method B was defined as the complement of the probability of inducing no cancer in N separate exposures. The risk of each separate exposure was estimated using dose, gender, and age at exposure (BEIR VII phase 2). Both methods were compared in a simulation and applied to a database of 11,884 patients exposed to multiple CTs. The relative difference between the methods was defined as ΔP%. Simulation confirmed that Method A always overestimates LAR(tot). ΔP% was proportional to the dose per exposure and the number of exposures. The differences between Methods A and B were small. Average LAR(tot) of tumor incidence was 0.140% (Method A) and 0.139% (Method B) with maxima of 5.70% and 5.56%, respectively. Average LAR(tot) of mortality was 0.085% for both methods, with maxima of 2.20% and 2.18%, respectively. ΔP% was highest (2.43%) for a female patient (3-y old) exposed to eight recurrent scans and a cumulative dose of 144 mSv. Although Method B is more accurate, both methods can be used to estimate the cumulative risk of multiple CT exposures. These results have to be interpreted, however, in the perspective of the uncertainties in the cancer risk model, which have been estimated at a factor of 2 or 3.

Multimodal MRI-based Imputation of the Aβ+ in Early Mild Cognitive Impairment

Objective

The primary goal of this study was to identify brain atrophy from structural MRI (magnetic resonance imaging) and cerebral blood flow (CBF) patterns from arterial spin labeling perfusion MRI that are best predictors of the Aβ-burden, measured as composite ¹⁸F-AV45-PET (positron emission tomography) uptake, in individuals with early mild cognitive impairment (MCI). Furthermore, another objective was to assess the relative importance of imaging modalities in classification of Aβ+/Aβ− early MCI.

Methods

Sixty-seven Alzheimer's Disease Neuroimaging Initiative (ADNI)-GO/2 participants with early MCI were included. Voxel-wise anatomical shape variation measures were computed by estimating the initial diffeomorphic mapping momenta from an unbiased control template. CBF measures normalized to average motor cortex CBF were mapped onto the template space. Using partial least squares regression, we identified the structural and CBF signatures of Aβ after accounting for normal cofounding effects of age, gender, and education.

Results

¹⁸F-AV45-positive early MCIs could be identified with 83% classification accuracy, 87% positive predictive value, and 84% negative predictive value by multidisciplinary classifiers combining demographics data, ApoE ε4-genotype, and a multimodal MRI-based Aβ score.

Interpretation

Multimodal MRI can be used to predict the amyloid status of early-MCI individuals. MRI is a very attractive candidate for the identification of inexpensive and noninvasive surrogate biomarkers of Aβ deposition. Our approach is expected to have value for the identification of individuals likely to be Aβ+ in circumstances where cost or logistical problems prevent Aβ detection using cerebrospinal fluid analysis or Aβ-PET. This can also be used in clinical settings and clinical trials, aiding subject recruitment and evaluation of treatment efficacy. Imputation of the Aβ-positivity status could also complement Aβ-PET by identifying individuals who would benefit the most from this assessment.

Radiation risks associated with serial imaging in colorectal cancer patients: Should we worry?

To provide an overview of the radiation related cancer risk associated with multiple computed tomographic scans required for follow up in colorectal cancer patients. A literature search of the PubMed and Cochrane Library databases was carried out and limited to the last 10 years from December 2012. Inclusion criteria were studies where computed tomographic scans or radiation from other medical imaging modalities were used and the risks associated with ionizing radiation reported. Thirty-six studies were included for appraisal with no randomized controlled trials. Thirty-four of the thirty-six studies showed a positive association between medical imaging radiation and increased risk of cancer. The radiation dose absorbed and cancer risk was greater in children and young adults than in older patients. Most studies included in the review used a linear, no-threshold model to calculate cancer risks and this may not be applicable at low radiation doses. Many studies are retrospective and ensuring complete follow up on thousands of patients is difficult. There was a minor increased risk of cancer from ionizing radiation in medical imaging studies. The radiation risks of low dose exposure (< 50 milli-Sieverts) are uncertain. A clinically justified scan in the context of colorectal cancer is likely to provide more benefits than harm but current guidelines for patient follow up will need to be revised to accommodate a more aggressive approach to treating metastatic disease.

Diagnostic radiation exposure of injury patients in the emergency department: a cross-sectional large scaled study

In contrast to patients with underlying cancer or chronic disease, injury patients are relatively young, and can be expected to live their natural lifespan if injuries are appropriately treated. Multiple and repeated diagnostic scans might be performed in these patients during admission. Nevertheless, radiation exposure in injury patients has been overlooked and underestimated because of the emergent nature of such situations. Therefore, we tried to assess the cumulative effective dose (cED) of injury patients in the emergency department. We included patients who visited the emergency department (ED) of a single tertiary hospital due to injury between February 2010 and February 2011. The cED for each patient was calculated and compared across age, sex and injury mechanism. A total of 11,676 visits (mean age: 28.0 years, M:F = 6,677:4,999) were identified. Although CT consisted of only 7.8% of total radiologic examinations (n=78,025), it accounted for 87.1% of the total cED. The mean cED per visit was 2.6 mSv. A significant difference in the cED among injury mechanisms was seen (p<0.001) and patients with traffic accidents and fall down injuries showed relatively high cED values. Hence, to reduce the cED of injury patients, an age-, sex- and injury mechanism-specific dose reduction strategy should be considered.

A descriptive study of access to services in a random sample of Canadian rural emergency departments

OBJECTIVE

To examine 24/7 access to services and consultants in a sample of Canadian rural emergency departments (EDs).

DESIGN

Cross-sectional study-mixed methods (structured interview, survey and government data bases) with random sampling of hospitals.

SETTING

Canadian rural EDs (rural small town (RST) definition-Statistics Canada).

PARTICIPANTS

28% (95/336) of Canadian rural EDs providing 24/7 physician coverage located in hospitals with acute care hospitalisation beds.

MAIN OUTCOME MEASURES

General characteristics of the rural EDs, information about 24/7 access to consultants, equipment and services, and the proportion of rural hospitals more than 300 km from levels 1 and 2 trauma centres.

RESULTS

Of the 336 rural EDs identified, 122 (36%) were randomly selected and contacted. Overall, 95 EDs participated in the study (participation rate, 78%). Hospitals had, on an average, 23 acute care beds, 7 ED stretchers and 13 500 annual ED visits. The proportion of rural hospitals with local access to the following 24/7 services was paediatrician, 5%; obstetrician, 10%; psychiatrist, 11%; internist, 12%; intensive care unit, 17%; CT scanner, 20%; surgeon, 26%; ultrasound, 28%; basic X-ray, 97% and laboratory services, 99%. Forty-four per cent and 54% of the RST EDs were more than 300 km from a level 1 and level 2 trauma centre, respectively.

CONCLUSIONS

This is the first study describing the services available in Canadian rural EDs. Apart from basic laboratory and X-ray services, most rural EDs have limited access to consultants, advanced imaging and critical care services. A detailed study is needed to evaluate the impact of these limited services on patient outcomes, costs and interfacility transport demands.

Nonconcordance between Clinical and Head CT Findings: The Specter of Overdiagnosis

Background. It is unclear whether history and physical examination findings can predict abnormalities on head computed tomography (CT) believed to indicate increased risk of lumbar-puncture- (LP-) induced brain herniation. The objectives of this study were to (1) identify head CT findings felt to be associated with increased risk of brain herniation and (2) to assess the ability of history and physical examination to predict those findings. Methods. Using a modified Delphi survey technique, an expert panel defined CT abnormalities felt to predict increased risk of LP-induced brain herniation. Presence of such findings on CT was compared with history and physical examination (H&P) variables in 47 patients. Results. No H&P variable predicted “high-risk” CT; combining H&P variables to improve sensitivity led to extremely low specificity and still failed to identify all patients with high-risk CT. Conclusions. “High-risk” CT is not uncommon in patients with clinical characteristics known to predict an absence of actual risk from LP, and thus it may not be clinically relevant. “Overdiagnosis” will be increasingly problematic as technological advances identify increasingly subtle deviations from “normal.”

Neuroimaging predictors of brain amyloidosis in mild cognitive impairment

OBJECTIVE

To identify a neuroimaging signature predictive of brain amyloidosis as a screening tool to identify individuals with mild cognitive impairment (MCI) that are most likely to have high levels of brain amyloidosis or to be amyloid-free.

METHODS

The prediction model cohort included 62 MCI subjects screened with structural magnetic resonance imaging (MRI) and (11) C-labeled Pittsburgh compound B positron emission tomography (PET). We identified an anatomical shape variation-based neuroimaging predictor of brain amyloidosis and defined a structural MRI-based brain amyloidosis score (sMRI-BAS). Amyloid beta positivity (Aβ(+) ) predictive power of sMRI-BAS was validated on an independent cohort of 153 MCI patients with cerebrospinal fluid Aβ1-42 biomarker data but no amyloid PET scans. We compared the Aβ(+) predictive power of sMRI-BAS to those of apolipoprotein E (ApoE) genotype and hippocampal volume, the 2 most relevant candidate biomarkers for the prediction of brain amyloidosis.

RESULTS

Anatomical shape variations predictive of brain amyloidosis in MCI embraced a characteristic spatial pattern known for high vulnerability to Alzheimer disease pathology, including the medial temporal lobe, temporal-parietal association cortices, posterior cingulate, precuneus, hippocampus, amygdala, caudate, and fornix/stria terminals. Aβ(+) prediction performance of sMRI-BAS and ApoE genotype jointly was significantly better than the performance of each predictor separately (area under the curve [AUC] = 0.88 vs AUC = 0.70 and AUC = 0.81, respectively) with >90% sensitivity and specificity at 20% false-positive rate and false-negative rate thresholds. Performance of hippocampal volume as an independent predictor of brain amyloidosis in MCI was only marginally better than random chance (AUC = 0.56).

INTERPRETATION

As one of the first attempts to use an imaging technique that does not require amyloid-specific radioligands for identification of individuals with brain amyloidosis, our findings could lead to development of multidisciplinary/multimodality brain amyloidosis biomarkers that are reliable, minimally invasive, and widely available.

Cumulative radiation dose in patients with hereditary hemorrhagic telangiectasia and pulmonary arteriovenous malformations

PURPOSE

To determine the cumulative effective dose (CED) of radiation from medical imaging and intervention in patients with hereditary hemorrhagic telangiectasia (HHT) who have pulmonary arteriovenous malformations and to identify clinical factors associated with exposure to high levels of radiation.

METHODS

All patients with at least 1 pulmonary arteriovenous malformation were identified from the dedicated patient database of a tertiary HHT referral centre. Computerized imaging and electronic patient records were systematically examined to identify all imaging studies performed from 1989-2010. The effective dose was determined for each study, and CED was calculated retrospectively.

RESULTS

Among 246 patients (mean age, 53 years; 62.2% women) with a total of 2065 patient-years, 3309 procedures that involved ionizing radiation were performed. CED ranged from 0.2-307.6 mSv, with a mean of 51.7 mSv. CED exceeded 100 mSv in 26 patients (11%). Interventional procedures and computed tomography (CT) were the greatest contributors, which accounted for 51% and 46% of the total CED, respectively. Factors associated with high cumulative exposure were epistaxis (odds ratio 2.7 [95% confidence interval, 1.1-6.3]; P = .02), HHT-related gastrointestinal bleeding (odds ratio 2.0 [95% confidence interval, 1.0-3.8]; P = .04) and number of patient-years (P < .0001).

CONCLUSIONS

Patients with HHT are exposed to a significant cumulative radiation dose from diagnostic and therapeutic interventions. Identifiable subsets of patients are at increased risk. A proportion of patients receive doses at levels that are associated with harm. Imaging indications and doses should be optimized to reduce radiation exposure in this population.

Radiation exposure among patients with the highest CT scan utilization in the emergency department

The risk of cancer from computed tomography (CT) scan radiation is a rising concern in the medical field. Our objectives were to determine how many patients received more than ten CT scans in an academic emergency department (ED) over the course of 7 years and to quantify their radiation exposure and lifetime attributable risk of cancer. An electronic chart review was performed at our urban academic institution with an annual census of 110,000 patients. All patients who underwent a CT scan performed during ED management between the dates of January 2001 and December 2007 were identified. Specific predetermined data elements (e.g., subject demographics, type of CT scan) were extracted by two researchers blinded to hypothesis, using a preformatted data form. After identifying patients with more than ten CTs performed during the study period, radiation exposure was calculated based on accepted and reported radiation doses for the respective anatomic CTs, and lifetime attributable cancer risk was calculated based on the seventh report of the Biological Effects of Ionizing Radiation (BEIR VII) projections. Over the 7-year study period, 24,393 patients received 34,671 CT scans. The vast majority of patients (17,909) received a single CT. Twenty-six (0.1 %) patients received more than ten CTs totaling 374 scans with an average radiation exposure of 83.4 mSv. The maximum lifetime attributable risk for any individual in this cohort was 1.7 % above the baseline cancer risk. Among those undergoing CT imaging in our ED, high-exposure patients (greater than ten scans) constituted a significant minority, while more than one in four patients underwent more than one CT scan during the study period. While the presumed overall risk of radiation-induced cancer continues to be low, it is important for the emergency physician to use clinical knowledge as well as concern for the patient when utilizing radiographic imaging. Increasing attributable cancer risk may have important public health implications in the future, regardless of the low individual risk.

Airway, breathing, computed tomographic scanning: duplicate computed tomographic imaging after transfer to trauma center

BACKGROUND

Trauma patients imaged at community hospitals often receive duplicate computed tomographic (CT) imaging after transfer to regional trauma centers (RTCs). CT scanning is expensive, is resource intensive, and has acknowledged radiation risk to the patient. The objective of this study was to review and evaluate the frequency, indications, impact on patient management, as well as associated radiation and charges for duplicate CT imaging of trauma patients transferred to our RTC from outside hospitals (OSH).

METHODS

Patients transferred to our RTC between September 2009 and August 2010 were evaluated prospectively. The OSH patients' charts and provider interviews were used to determine the reasons for repeated scans. The primary outcome was frequency of duplicate CT scan, defined as a repeated CT image of the same body part within 24 hours. The reason for duplicate imaging and impact on patient management was categorized. Radiation exposure and charges for duplicate scans were also determined.

RESULTS

Of the 185 patients transferred to our facility, 177 were eligible. CT examinations at the OSH were performed on 137 patients (77%). A duplicate CT examination occurred in 38 patients (28%). The most common reason for duplicate CT scanning was lack of thin-section multiplanar data, on images sent via CD-ROM (37%). There was a change in management in 16 patients (42%). The patients with duplicate scanning received a median of 10.2 mSv (interquartile range, 6.6-15.7 mSv) of additional radiation, with a median charge of $409 (interquartile range, $307-$734).

CONCLUSION

More than one third of duplicated scans performed on transferred trauma patients were potentially avoidable, primary owing to inadequate transfer of data from the OSH CT scan. The capacity of a single CD-ROM is insufficient to contain full imaging data from a trauma scan, and establishing direct links to imaging data from OSHs would decrease the number of repeated CT scans performed on transferred trauma patients.

LEVEL OF EVIDENCE

Care management study, level III.

Cumulative radiation dose from medical imaging in chronic adult patients

Chronic patients require ongoing care that results in repeated imaging and exposure to ionizing radiation for both diagnostic and therapeutic purposes. This is of concern due to the long-term effects of radiation exposure, namely the association between radiation and increased cancer risk. In this study, the scientific literature on cumulated dose of radiation accrued from medical imaging by 4 cohorts of chronic patients (cardiac disease, end-stage kidney disease, inflammatory bowel disease, and patients undergoing endovascular aortic repair) was systematically reviewed. We found that the cumulative effective dose is moderate in cardiac and inflammatory bowel disease patients, high in end-stage kidney disease patients, and very high in endovascular aortic repair patients. We concluded that radiation burden of medical imaging is high in selected cohorts of chronic patients. Efforts should be implemented to reduce this cumulative dose and its potential attendant risks.

Parental knowledge of radiation exposure in medical imaging used in the pediatric emergency department

OBJECTIVES

We sought to quantify the knowledge base among parents and legal guardians presenting to our pediatric emergency department regarding radiation exposure during medical imaging and potential risks to children resulting from ionizing radiation. We sought to examine if a child's previous exposure to medical imaging changed caregiver knowledge base and discern caregivers' preference for future education on this topic.

METHODS

A prospective convenience sample survey was performed of caregivers who presented with their child to our tertiary pediatric emergency department. Parents or legal guardians (18-89 years) who accompanied a child (0-17 years) were eligible for inclusion and approached for enrollment. A structured questionnaire was administered by trained interviewers, and a chart review was conducted to ascertain if their child had a history of previous imaging.

RESULTS

Sixty percent of caregivers interviewed (n = 205 of 340) did not associate any long-term negative effects with medical imaging. Among participants who did express a perceived risk from medical imaging radiation exposure, only 50% could indicate a known negative effect from exposure. We found no significant association between a child having had documented imaging studies and awareness of long-term negative effects (P = 0.22). Participants preferred to learn more about this topic from an Internet-based resource (50%), informational pamphlet (38%), or via treating physician (33%).

CONCLUSIONS

Parents and legal guardians are largely unaware that exposure to radiation during medical imaging carries an inherent risk for their child. Health care providers wishing to educate caregivers should utilize reliable Internet sources, educational pamphlets, and direct communication.

Strategies for Reducing Radiation Exposure from Multidetector Computed Tomography in the Acute Care Setting

Many tools and strategies exist to enable reduction of radiation exposure from computed tomography (CT). The common CT metrics of x-ray output, the volume CT dose index and the dose-length product, are explained and serve as the basis for monitoring radiation exposure from CT. Many strategies to dose-optimize CT protocols are explored that, in combination with available hardware and software tools, allow robust diagnostic quality CT to be performed with a radiation exposure appropriate for the clinical scenario and the size of the patient. Specific emergency department example protocols are used to demonstrate these techniques.

Radiation-induced tumours of meninges. Report on eight cases and review of the literature

BACKGROUND AND PURPOSE

Despite their rarity, post-radiation meningeal tumours seem to be a growing problem due to the increasing application of radiation therapy. The aim of the study was to ascertain the specific features of these tumours.

MATERIAL AND METHODS

Among 433 intracranial meningeal tumours treated from 2000 to 2008, eight cases (2%) have been presumed to be associated with high-dose therapeutic radiation for previous neoplasm of the head (7) or neck (1). On average, tumours were diagnosed 24 years after irradiation. All patients had a solitary meningeal tumour, but two of them also developed other neoplasms in the irradiated area.

RESULTS

All tumours were microsurgically removed. The post-operative course was uncomplicated in two cases only. In the remaining 6 (75%), complications included liquorrhoea (2), brain oedema (1), venous thrombosis (1), bleeding into the tumour bed (1) and focal deficit due to manipulation (3). Most tumours (5) were WHO grade I meningiomas. These benign meningiomas exhibited some peculiar histological features, including focal increase of cellularity, focal enhancement of proliferation index, pleomorphism of nuclei, occasional mitotic figures and, in one case, evidence of brain invasion. One meningioma was assigned to WHO grade II, one to WHO grade III and one appeared to be meningeal fibrosarcoma. The event-free survival and overall survival rate at 4.4 years of follow-up were 63% and 75%, respectively.

CONCLUSIONS

Radiation-induced tumours of the meninges show certain characteristic histopathological features, which may promote invasiveness of the tumour and higher risk of malignancy.

Utility of repeated abdominal CT scans after prior negative CT scans in patients presenting to ER with nontraumatic abdominal pain

PURPOSE

The purpose of this study was to analyze diagnostic yield of repeat computed tomography (CT) after negative initial CT versus yield of initial CT in patients presenting repeatedly to emergency room (ER) for nontraumatic abdominal pain. Medical costs and radiation exposure from repeat CT could be reduced if repeat CT after negative initial CT has a low diagnostic yield.

METHODS

Patients included consecutive adults presenting to William Beaumont Hospital, from 2007 to 2010, undergoing abdominal CT for nontraumatic abdominal pain retrospectively identified by medical diagnostic and CT procedural codes. Exclusion criteria were prior abdominal trauma, recent abdominal surgery, and known chronic gastrointestinal disease. The CT was labeled "positive" if findings explained patient's abdominal pain or was clinically significant. Positivity rate was compared for repeat versus initial CT.

RESULTS

Among 200 consecutive patients undergoing (659) multiple CTs (mean age = 45.7 years, 74 % female), positivity rate for initial CT (22.5 %) was significantly higher than positivity rates for CT#2 (8.4 %, p = 0.002), for CT#3 (4.9 %, p = 0.005), and for CT ≥ #4 (5.9 %, p = 0.006). Generally, CT positivity rate declined with increasing number of prior negative CTs. CT positivity rate was significantly higher in 100 patients undergoing single CT versus 155 patients undergoing repeat CTs (46.5 vs. 6.5 %, p = 0.0001). Positive repeat CT findings included intestinal mural thickening/mass (7), colitis (5), appendicitis (4), and other (14). Among 15 analyzed clinical parameters, two significantly predicted repeat CT positivity, namely, leukocytosis (p = 0.03) and APACHE-II-score >5 (p = 0.01). Repeat CTs constituted 47 % of all CTs.

CONCLUSIONS

Repeat abdominal CT after initially negative CT(s) performed for nontraumatic abdominal pain has a low diagnostic yield. Leukocytosis and APACHE-II score might help predict CT scan positivity. Data suggest restricted abdominal CT utilization in ER patients with multiple prior negative CTs. Findings warrant confirmation in prospective studies.

Real practice radiation dose and dosimetric impact of radiological staff training in body CT examinations

OBJECTIVES

To evaluate the radiation dose of the main body CT examinations performed routinely in four regional diagnostic centres, the specific contribution of radiologists and technologists in determining CT dose levels, and the role of radiological staff training in reducing radiation doses.

METHODS

We retrospectively evaluated the radiation dose in terms of dose-length product (DLP) values of 2,016 adult CT examinations (chest, abdomen-pelvis, and whole body) collected in four different centres in our region. DLP values for contrast-unenhanced and contrast-enhanced CT examinations performed at each centre were compared for each anatomical area. DLP values for CT examinations performed before and after radiological staff training were also compared.

RESULTS

DLP values for the same CT examinations varied among centres depending on radiologists' preferences, variable training of technologists, and diversified CT image acquisition protocols. A specific training programme designed for the radiological staff led to a significant overall reduction of DLP values, along with a significant reduction of DLP variability.

CONCLUSIONS

Training of both radiologists and technologists plays a key role in optimising CT acquisition procedures and lowering the radiation dose delivered to patients.

MAIN MESSAGES

• The effective dose for similar CT examinations varies significantly among radiological centres. • Staff training can significantly reduce and harmonise the radiation dose. • Training of radiologists and technologists is key to optimise CT acquisition protocols.

Radiology stewardship and quality improvement: the process and costs of implementing a CT radiation dose optimization committee in a medium-sized community hospital system

PURPOSE

The aims of this study were to measure the effectiveness of a multidisciplinary CT dose optimization committee and estimate its costs and to describe a radiation stewardship quality improvement initiative in one CT department at a medium-sized community hospital system that used a participatory design committee methodology.

METHODS

A CT dose optimization committee was conceived, funded, and formed, consisting of the following stakeholders: radiologists, technologists, consultant medical physicists, and an administrator. Volume CT dose index (CTDIvol) and repeat rate were monitored for 1 month, for one scan type, during which iterative protocol adjustments were made through committee interaction. Effects on repeat rate and CTDIvol were quantified and benchmarked against national diagnostic reference levels after retrospective medical record review of 100 consecutive patients before and after the intervention. Labor hours were reported and wage resources estimated.

RESULTS

Over 3 months, the committee met in person twice and exchanged 128 e-mails in establishing a process for protocol improvement and measurement of success. Repeat rate was reduced from 13% (13 of 100) to 0% (0 of 100). Scans meeting the ACR reference level for CTDIvol (75 mGy) improved by 34% (38 of 100 before, 51 of 100 after; Fisher's exact 2-tailed P = .09), and those meeting ACR pass/fail criterion (80 mGy) improved by 29% (58 of 100 before, 75 of 100 after; Fisher's exact 2-tailed P = .01). Committee evolution and work, and protocol development and implementation, required 57 person-hours, at an estimated labor cost of $12,488.

CONCLUSIONS

An efficient process was established as a proof of concept for the use of a multidisciplinary committee to reduce patient radiation dose, repeat rate, and variability in image quality. The committee and process ultimately improved the quality of patient care, fostered a culture of safety and ongoing quality improvement, and calculated costs for such an endeavor.

Emergency department visits, use of imaging, and drugs for urolithiasis have increased in the United States

The occurrence of urolithiasis in the United States has increased; however, information on long-term trends, including recurrence rates, is lacking. Here we describe national trends in rates of emergency department visits, use of imaging, and drug treatment, primarily using the National Hospital Ambulatory Medical Care Survey to describe trends and the National Health and Nutrition Examination Survey to determine the frequency of lifetime passage of kidney stones. Emergency department visit rates for urolithiasis increased from 178 to 340 visits per 100,000 individuals from 1992 to 2009. Increases in visit rates were greater in women, Caucasians, and in those aged 25-44 years. The use of computed tomography in urolithiasis patients more than tripled, from 21 to 71%. Medical expulsive therapy was used in 14% of the patients with a urolithiasis diagnosis in 2007-2009. Among National Health and Nutrition Examination Survey participants who reported a history of kidney stones, 22.4% had passed three or more stones. Hence, emergency department urolithiasis visit rates have increased significantly, as has the use of computed tomography in the United States. Further research is necessary to determine whether recurrent stone formers receive unnecessary radiation exposure during diagnostic evaluation in the emergency department and allow development of corresponding evidence-based guidelines.

Computed Tomography Associated Cancers and Cancer Deaths Following Visits to U.S. Emergency Departments

We estimated the number of future cancers and cancer deaths following computed tomography scans (CTs) performed in U.S. emergency departments annually and determined whether increases in the proportion of visits resulting in CTs over the past decade were accompanied by changes in markers of severity of illness or primary reason for visit. We applied national estimates of effective dose to adult emergency department visits in the 2008 National Hospital Ambulatory Medical Care Survey. We utilized the Biologic Effects of Ionizing Radiation Model VII to estimate the number of future cancers and cancer deaths caused by CTs performed in U.S. emergency departments. We calculated the proportion of visits resulting in CTs from 1998 to 2008. In 2008, 16,406,921 CTs were performed nationally on adults, which will cause an estimated 3,750 cancers and 1,994 cancer deaths. The increasing proportion of emergency department visits resulting in CTs was not accompanied by proportional increases in markers of severity of illness or primary reason for visit. The substantial number of future cancers and cancer deaths attributable to CTs and increases in CTs without accompanying increases in markers of severity or changes in primary reason for visit highlight the importance of examining the benefits of CTs.

Radiation dose from medical imaging: a primer for emergency physicians

Introduction

Medical imaging now accounts for most of the US population's exposure to ionizing radiation. A substantial proportion of this medical imaging is ordered in the emergency setting. We aim to provide a general overview of radiation dose from medical imaging with a focus on computed tomography, as well as a literature review of recent efforts to decrease unnecessary radiation exposure to patients in the emergency department setting.

Methods

We conducted a literature review through calendar year 2010 for all published articles pertaining to the emergency department and radiation exposure.

Results

The benefits of imaging usually outweigh the risks of eventual radiation-induced cancer in most clinical scenarios encountered by emergency physicians. However, our literature review identified 3 specific clinical situations in the general adult population in which the lifetime risks of cancer may outweigh the benefits to the patient: rule out pulmonary embolism, flank pain, and recurrent abdominal pain in inflammatory bowel disease. For these specific clinical scenarios, a physician-patient discussion about such risks and benefits may be warranted.

Conclusion

Emergency physicians, now at the front line of patients' exposure to ionizing radiation, should have a general understanding of the magnitude of radiation dose from advanced medical imaging procedures and their associated risks. Future areas of research should include the development of protocols and guidelines that limit unnecessary patient radiation exposure.

Changing Radiation Dose from Diagnostic Computed Tomography Examinations in Saskatchewan

Purpose

Follow-up study to observe if provincial mean effective radiation dose for head, chest, and abdomen-pelvis (AP) computed tomographies (CTs) remained stable or changed since the initial 2006 survey.

Methods

Data were collected in July 2008 from Saskatchewan's 13 diagnostic CT scanners of 3358 CT examinations. These data included the number of scan phases and projected dose length product (DLP). Technologists compared projected DLP with 2006 reference data before scanning. Projected DLP was converted to effective dose (ED) for each head, chest, and AP CT. The total dose that the patients received with scans of multiple body parts at the same visit also was determined.

Results

The mean (± SD) provincial ED was 3.4 ± 1.6 mSv for 1023 head scans (2.7 ± 1.6 mSv in 2006), 9.6 ± 4.8 mSv for 588 chest scans (11.3 ± 8.9 mSv in 2006), and 16.1 ± 9.9 mSv for 983 AP scans (15.5 ± 10.0 mSv in 2006). Single-phase multidetector row CT ED decreased by 31% for chest scans (9.5 ± 3.9 mSv vs 13.7 ± 9.7 mSv in 2006) and 17% for AP scans (13.9 ± 6.0 mSv vs 16.8 ± 10.6 mSv in 2006) and increased by 19% for head scans (3.2 ± 1.2 mSv vs 2.7 ± 1.5 mSv in 2006). The total patient dose was highest (33.8 ± 10.1 mSv) for the 20 patients who received head, neck, chest, and AP scans during a single visit. Because of increased utilisation and the increased CT head dose, Saskatchewan per capital radiation dose from CT increased by 21% between 2006 and 2008 (1.14 vs 1.38 mSv/person per year).

Conclusion

Significant dose and variation reduction was seen for single-phase CT chest and AP examinations between 2006 and 2008, whereas CT head dose increased over the same interval. These changes, combined with increased utilisation, resulted in per capita increase in radiation dose from CT between the 2 studies.

Benefit of the Vittel criteria to determine the need for whole body scanning in a severe trauma patient

OBJECTIVE

To evaluate the use of the Vittel criteria in addition to a clinical examination to determine the need for a whole body scan (WBS) in a severe trauma patient.

MATERIALS AND METHODS

Between December 2008 and November 2009, 339 severe trauma patients with at least one Vittel criterion were prospectively evaluated with a WBS. The following data were collected: the Vittel criteria present, circumstances of the accident, traumatic injury on the WBS, and irradiation. The original intent to prescribe a computed tomography (CT) scan (whole body or a targeted region), based solely on clinical signs, was specified.

RESULTS

Injuries were diagnosed in 55.75% of the WBS (n=189). The most common Vittel criteria were "global assessment" (n=266), "thrown, run over" (n=116), and "ejected from vehicle" (n=94). The multivariate analysis used the following as independent criteria for predicting severe traumatic injury on the WBS: Glasgow score less than 13, penetrating trauma, and colloid resuscitation greater than 11. Based solely on clinical factors, 164 patients would not have had any scan or (only) a targeted scan. In that case, 15% of the severe injuries would have been missed.

CONCLUSION

Using the Vittel criteria to determine the need for a WBS in a severe trauma patient makes it possible to find serious injuries not suspected on the clinical examination, but at the cost of an increased number of normal scans.

Research and technology in neurocritical care

The daily practice of neurointensivists focuses on the recognition of subtle changes in the neurological examination, interactions between the brain and systemic derangements, and brain physiology. Common alterations such as fever, hyperglycemia, and hypotension have different consequences in patients with brain insults compared with patients of general medical illness. Various technologies have become available or are currently being developed. The session on "research and technology" of the first neurocritical care research conference held in Houston in September of 2009 was devoted to the discussion of the current status, and the research role of state-of-the art technologies in neurocritical patients including multi-modality neuromonitoring, biomarkers, neuroimaging, and "omics" research (proteomix, genomics, and metabolomics). We have summarized the topics discussed in this session. We have provided a brief overview of the current status of these technologies, and put forward recommendations for future research applications in the field of neurocritical care.