Impact of X-Ray Exposure From Computed Tomography on Wearable Insulin Delivery Devices.

BACKGROUND: To investigate the impact of radiation exposure from a computed tomography (CT) scanner on the functional integrity of a wearable insulin delivery system. METHODS: A total of 160 Omnipods and four personal diabetes managers (PDMs) were evenly divided into four groups: (1) control group (no radiation exposure), (2) typical radiation exposure group, (3) 4× typical radiation exposure group, and (4) scatter radiation group. Pods were attached to an anthropomorphic torso phantom on the abdomen (direct irradiation) or shoulder (scatter radiation) region. A third-generation dual-source CT scanner was used to scan the pods using either a typical exposure (used for routine CT abdominal study of a median size patient) or 4× typical exposure. A manufacturer-recommended 20-step functionality test was performed for all 160 Omnipods. RESULTS: The radiation dose (measured in volume CT Dose index) was 16 mGy for a typical exposure, and 64 mGy for 4× typical exposure. The scatter radiation is less than 0.1 mGy. All Pods passed the functionality test except one pod in the scatter radiation group, which sounded an alarm due to occlusion. The blockage to the fluid was due to a kink in the soft cannula, a mechanical issue not caused by the radiation exposure. CONCLUSIONS: This study suggests X-ray exposure levels used in radiological imaging procedures do not negatively impact the functional integrity of Omnipods. This finding may support the potential for the manufacturer to remove the warning that patients should remove the Pod for X-ray imaging procedures, which will have a huge impact on patient care.

Effect of obesity on ability to lower exposure for detection of low-attenuation liver lesions.

PURPOSE: The purpose of this study was to assess the effect of obesity and iterative reconstruction on the ability to reduce exposure by studying the accuracy for detection of low-contrast low-attenuation (LCLA) liver lesions on computed tomography (CT) using a phantom model. METHODS: A phantom with four unique LCLA liver lesions (5- to 15-mm spheres, -24 to -6 HU relative to 90-HU background) was scanned without ("thin" phantom) and with ("obese" phantom) a 5-cm thick fat-attenuation ring at 150 mAs (thin phantom) and 450 mAs (obese phantom) standard exposures and at 33% and 67% exposure reductions. Images were reconstructed using standard filtered back projection (FBP) and with iterative reconstruction (Adaptive Model-Based Iterative Reconstruction strength 3, ADMIRE). A noninferiority analysis of lesion detection was performed. RESULTS: Mean area under the curve (AUC) values for lesion detection were significantly higher for the thin phantom than for the obese phantom regardless of exposure level (P < 0.05) for both FBP and ADMIRE. At 33% exposure reduction, AUC was noninferior for both FBP and ADMIRE strength 3 (P < 0.0001). At 67% exposure reduction, AUC remained noninferior for the thin phantom (P < 0.0035), but was no longer noninferior for the obese phantom (P ≥ 0.7353). There were no statistically significant differences in AUC between FBP and ADMIRE at any exposure level for either phantom. CONCLUSIONS: Accuracy for lesion detection was not only significantly lower in the obese phantom at all relative exposures, but detection accuracy decreased sooner while reducing the exposure in the obese phantom. There was no significant difference in lesion detection between FBP and ADMIRE at equivalent exposure levels for either phantom.

Technical Note: Characterization of x-ray beam profiles for a fluoroscopic system incorporating copper filtration.

PURPOSE: The goal of this study was to investigate x-ray beam profiles at various water depths to characterize the two-dimensional x-ray dose distribution, allowing for off-axis and out-of-field radiation dose estimation for a wide range of x-ray beam spectra commonly encountered in fluoroscopically guided interventional procedures. METHODS: A Siemens Artis interventional fluoroscope was operated in a service mode to generate a continuous x-ray beam at fixed x-ray beam spectra, defined by their kVp and the thickness of additional copper filtration. A PTW scanning water tank with a diode detector was used to measure the x-ray beam profiles at several depths in water at various fields of view and x-ray beam spectra, both parallel and perpendicular to the anode-cathode axis direction. RESULTS: X-ray beam profiles, including out-of-field tails, were characterized for a wide range of beam qualities. The anode heel effect was pronounced even at depth, resulting in large dose variations across the x-ray field; this effect was even more definite at large fields of view, at higher kVps, and in the absence of additional copper filtration. CONCLUSIONS: This study investigated and characterized 2D radiation dose deposition in water from x-ray beam spectra commonly used by modern fluoroscopes in interventional procedures. This knowledge can be applied to manual dosimetry calculations or can be used to refine the accuracy of automated dose mapping tools or Monte Carlo simulations of the radiation dose to soft tissue within the x-ray field and to tissue adjacent to the primary beam. Additionally, this study illustrates a substantial reduction of the anode heel effect by using moderate amounts of additional copper filtration to harden the x-ray beam spectrum.

Radiation Exposure in the Medical ICU: Predictors and Characteristics.

BACKGROUND: Patients admitted to the medical ICU (MICU) are often subjected to multiple radiologic studies. We hypothesized that some endure radiation dose exposure (cumulative effective dose [CED]) in excess of annual US federal occupational health standard limits (CED ≥ 50 mSv) and 5-year cumulative limit (CED ≥ 100 mSv). We also evaluated the correlation of CED with Acute Physiology and Chronic Health Evaluation (APACHE) III score and other clinical variables. METHODS: Retrospective observational study conducted in an academic medical center involving all adult admissions (N = 4,155) to the MICU between January 2013 and December 2013. Radiation doses from ionizing radiologic studies were calculated from reference values to determine the CED. RESULTS: Three percent of admissions (n = 131) accrued CED ≥ 50 mSv (1% [n = 47] accrued CED ≥ 100 mSv). The median CED was 0.72 mSv (interquartile range, 0.02-5.23 mSv), with a range of 0.00 to 323 mSv. Higher APACHE III scores (P = .003), longer length of MICU stay (P < .0001), sepsis (P = .03), and gastrointestinal disorders and bleeding (P < .0001) predicted higher CED in a multivariable linear regression model. Patients with gastrointestinal bleeding and disorders had an odds ratio of 21.05 (95% CI, 13.54-32.72; P < .0001) and 6.94 (95% CI, 3.88-12.38; P < .0001), respectively, of accruing CED ≥ 50 mSv in a multivariable logistic regression model. CT scan and interventional radiology accounted for 49% and 38% of the total CED, respectively. CONCLUSIONS: Patients in the MICU are exposed to radiation doses that can be substantial, exceeding federal annual occupational limits, and in a select subset, are > 100 mSv. Efforts to justify, restrict, and optimize the use of radiologic resources when feasible are warranted.

Dose Reduction With Dedicated CT Metal Artifact Reduction Algorithm: CT Phantom Study.

OBJECTIVE: The objective of this study was to compare reader accuracy detecting lesions near hardware in a CT phantom model at different radiation exposures using an advanced metal artifact reduction (MAR) algorithm and standard filtered back projection (FBP) techniques and to determine if radiation exposure could be decreased using MAR without compromising lesion detectability. MATERIALS AND METHODS: A CT phantom manufactured with spherical lesions of various sizes (10-20 mm) and attenuations (20-50 HU) embedded around cobalt-chromium spheres attached to titanium rods, simulating an arthroplasty, was scanned on a single CT scanner (FLASH, Siemens Healthcare) at 140 kVp and 0.6-mm collimation using clinical-dose (300 Quality Reference mAs [Siemens Healthcare]), low-dose (150 Quality Reference mAs), and high-dose (600 Quality Reference mAs) protocols. Images reconstructed with iterative MAR, advanced modeled iterative reconstruction (ADMIRE), and FBP with identical parameters were anonymized and independently reviewed by three radiologists. Accuracies for detecting lesions, measured as AUC, sensitivity, and specificity, were compared. RESULTS: Accuracy using MAR was significantly higher than that using FBP at all exposures (p values ranged from < 0.001 to 0.021). Sensitivity was also higher for MAR than for FBP at all exposures. Specificity was very high for both reconstruction techniques at all exposures with no significant differences. Accuracy of low-dose MAR was higher than and not inferior to standard-dose and high-dose FBP. MAR was significantly more sensitive than FBP in detecting smaller lesions (p = 0.021) and lesions near high streak artifact (p < 0.001). CONCLUSION: MAR improves reader accuracy to detect lesions near hardware and allows significant reductions in radiation exposure without compromising accuracy compared with FBP in a CT phantom model.

Extending the concept of weighted CT dose index to elliptical phantoms of various aspect ratios.

The purpose of this study was to extend the concept of weighted CT dose index ([Formula: see text]) to the elliptical phantoms. Based on the published body dimension data, eight body aspect ratios were chosen between 1 (perfectly circular) and 1.72 (extremely elliptical). For each aspect ratio, two elliptical cylinders were created digitally to represent adult and pediatric bodies. Their cross-sectional areas were identical to the standard 32- and 16-cm CTDI phantoms. For each phantom, [Formula: see text] at center and periphery were simulated for tube voltages between 70 and 140 kVp using a validated Monte Carlo program. The simulations also provided the average dose over the cross-sectional area, [Formula: see text]. Values of [Formula: see text] and [Formula: see text] allowed linear systems of equations to be established, from which central and peripheral weighting coefficients were solved. Regardless of phantom shape, only two weighting coefficients were needed: [Formula: see text] for the central [Formula: see text] and [Formula: see text] for the average of the four peripheral [Formula: see text]'s. Over the full range of aspect ratios, [Formula: see text] increased linearly from 0.37 to 0.46, whereas [Formula: see text] decreased linearly from 0.63 to 0.54, allowing the concept of [Formula: see text] to be readily extended to the elliptical phantoms. When cross-sectional area (hence volume) was kept constant, all phantoms had the same [Formula: see text] regardless of shape.

Tobacco-free policies at worksites in Kansas.

BACKGROUND: This study sought to examine the relationship between tobacco-free policies at worksites to worksite demographics such as company size and geographic location. METHODS: Worksites participating in a worksite wellness workshop were asked to complete a worksite wellness instrument, which provided an assessment of their wellness practices already in place in the worksite, including the degree to which tobacco-free policies were in place at the worksite. RESULTS: At a bivariate level, those more likely to have tobacco-free policies included: urban employers (76.8% versus 50% rural employers, p = 0.0001); large employers (> = 250 employees) (74.3% versus 43.1% small employers (<50 employees), p = 0.0003); and schools (69.4%) and hospitals (61.5%) (versus 35.5%, agricultural/ manufacturing employers, p = 0.0125). At the multivariate level, rural employers (AOR = 0.47, 95% CI 0.23, 0.95) and small employers (AOR = 0.34, 95% CI 0.16, 0.71) had decreased odds, compared to their urban and large employer counterparts, of having tobacco-free policies. CONCLUSIONS: Rural and smaller employers are less likely to have tobacco-free policies than their urban and large counterparts.

Analysis of uncertainties in Monte Carlo simulated organ and effective dose in chest CT: scanner- and scan-related factors.

In Monte Carlo simulation of CT dose, many input parameters are required (e.g. bowtie filter properties and scan start/end location). Our goal was to examine the uncertainties in patient dose when input parameters were inaccurate. Using a validated Monte Carlo program, organ dose from a chest CT scan was simulated for an average-size female phantom using a reference set of input parameter values (treated as the truth). Additional simulations were performed in which errors were purposely introduced into the input parameter values. The effects on four dose quantities were analyzed: organ dose (mGy/mAs), effective dose (mSv/mAs), CTDIvol-normalized organ dose (unitless), and DLP-normalized effective dose (mSv/mGy · cm). At 120 kVp, when spectral half value layer deviated from its true value by ±1.0 mm Al, the four dose quantities had errors of 18%, 7%, 14% and 2%, respectively. None of the dose quantities were affected significantly by errors in photon path length through the graphite section of the bowtie filter; path length error as large as 5 mm produced dose errors of ⩽2%. In contrast, error of this magnitude in the aluminum section produced dose errors of ⩽14%. At a total collimation of 38.4 mm, when radiation beam width deviated from its true value by ± 3 mm, dose errors were ⩽7%. Errors in tube starting angle had little impact on effective dose (errors ⩽ 1%); however, they produced organ dose errors as high as 66%. When the assumed scan length was longer by 4 cm than the truth, organ dose errors were up to 137%. The corresponding error was 24% for effective dose, but only 3% for DLP-normalized effective dose. Lastly, when the scan isocenter deviated from the patient's anatomical center by 5 cm, organ and effective dose errors were up 18% and 8%, respectively.

Physician Practices Regarding SIDS in Kansas.

Sudden infant death syndrome (SIDS) is the leading cause of death among infants aged 1 to 12 months. The purpose of this study was to assess prenatal and postnatal physicians' knowledge about SIDS in a county with high rates of SIDS deaths. A cross-sectional survey was conducted of pediatricians, family practitioners, and obstetricians in Sedgwick County, Kansas. Most physicians reported correctly that there were effective measures to reduce SIDS. Most respondents agreed it was important to discuss SIDS with parents. Pediatricians were more likely than family practitioners and obstetricians to recognize that pacifier use is important for infants in their first year to reduce SIDS and 2 to 4 months is the age range for peak incidence of SIDS. Pediatricians, family practitioners, and obstetricians are knowledgeable about SIDS and SIDS risk reduction. However, they are not allocating adequate time for discussing SIDS and SIDS reduction efforts with patients.

Percent depth doses and X-ray beam characterizations of a fluoroscopic system incorporating copper filtration.

PURPOSE: In this investigation, we sought to characterize X-ray beam qualities and quantitate percent depth dose (PDD) curves for fluoroscopic X-ray beams incorporating added copper (Cu) filtration, such as those commonly used in fluoroscopically guided interventions (FGI). The intended application of this research is for dosimetry in soft tissue from FGI procedures using these data. METHODS: All measurements in this study were acquired on a Siemens (Erlangen, Germany) Artis zeego fluoroscope. X-ray beam characteristics of first half-value layer (HVL), second HVL, homogeneity coefficients (HCs), backscatter factors (BSFs) and kVp accuracy and precision were determined to characterize the X-ray beams used for the PDD measurements. A scanning water tank was used to measure PDD curves for 60, 80, 100, and 120 kVp X-ray beams with Cu filtration thicknesses of 0.0, 0.1, 0.3, 0.6, and 0.9 mm at 11 cm, 22 cm, and 42 cm nominal fields of view, in water depths of 0 to 150 mm. RESULTS: X-ray beam characteristics of first HVLs and HCs differed from previous published research of fluoroscopic X-ray beam qualities without Cu filtration. PDDs for 60, 80, 100, and 120 kVp with 0 mm of Cu filtration were comparable to previous published research, accounting for differences in fluoroscopes, geometric orientation, type of ionization chamber, X-ray beam quality, and the water tank used for data collection. PDDs and X-ray beam characteristics for beam qualities with Cu filtration are presented, which have not been previously reported. CONCLUSIONS: The data sets of X-ray beam characteristics and PDDs presented in this study can be used to estimate organ or soft tissue doses at depth involving similar beam qualities or to compare with mathematical models.

Attenuation-based kV pair selection in dual source dual energy computed tomography angiography of the chest: impact on radiation dose and image quality.

OBJECTIVES: The purpose of this study was to evaluate the impact of attenuation-based kilovoltage (kV) pair selection in dual source dual energy (DSDE)-pulmonary embolism (PE) protocol examinations on radiation dose savings and image quality. METHODS: A prospective study was carried out on 118 patients with suspected PE. In patients in whom attenuation-based kV pair selection selected the 80/140Sn kV pair, the pre-scan 100/140Sn CTDIvol (computed tomography dose index volume) values were compared with the pre-scan 80/140Sn CTDIvol values. Subjective and objective image quality parameters were assessed. RESULTS: Attenuation-based kV pair selection switched to the 80/140Sn kV pair ("switched" cohort) in 63 out of 118 patients (53%). The mean 100/140Sn pre-scan CTDIvol was 8.8 mGy, while the mean 80/140Sn pre-scan CTDIvol was 7.5 mGy. The average estimated dose reduction for the "switched" cohort was 1.3 mGy (95% CI 1.2, 1.4; p < 0.001), representing a 15% reduction in dose. After adjusting for patient weight, mean attenuation was significantly higher in the "switched" vs. "non-switched" cohorts in all five pulmonary arteries and in all lobes on iodine maps. CONCLUSIONS: This study demonstrates that attenuation-based kV pair selection in DSDE examination is feasible and can offer radiation dose reduction without compromising image quality. KEY POINTS: • Attenuation-based kV pair selection in dual energy examination is feasible. • It can offer radiation dose reduction to approximately 50% of patients. • Approximate 15% reduction in radiation dose was achieved using this technique. • The image quality is not compromised by use of attenuation-based kV pair selection.

Direct Primary Care in 2015: A Survey with Selected Comparisons to 2005 Survey Data.

INTRODUCTION: Direct primary care (DPC), a fee for membership type of practice, is an evolving innovative primary care delivery model. Little is known about current membership fees, insurance billing status, physician training, and patient panel size in DPC practices. This study aimed to obtain current data for these variables, as well as additional demographic and financial indicators, and relate the findings to the Healthy People 2020 goals. It was predicted that DPC practices would (1) submit fewer claims to insurance, (2) have decreased membership fees, (3) be primarily family medicine trained, and (4) have increased the projected patient panel size since 2005. METHODS: An electronic survey was sent to DPC practices (n = 65) requesting location, membership fees, projected patient panel size, insurance billing status, training, and other demographic and financial indicators. Data were aggregated, reported anonymously, and compared to two prior characterizations of DPC practices done in 2005. RESULTS: Thirty-eight of 65 (59%) practices responded to the 2015 survey. The majority of respondents (84%) reported using an EMR, offering physician email access (82%), 24-hour access (76%), same day appointments (92%), and wholesale labs (74%). Few respondents offered inpatient care (16%), obstetrics (3%), or financial/insurance consultant services. Eighty-eight percent (88%) of practices reported annual individual adult membership rates between $500 and $1,499, decreased from 2005 where 81% reported greater than a $1,500 annual fee. The proportion of practices who submit bills to insurance decreased from 75% in 2005 to 11% in 2015. Fifty-six percent (56%) of practices reported projected patient panel size to be greater than 600, increased from 40% in 2005. Family medicine physicians represented 87% of respondents, markedly different from 2005 when 62 - 77% of DPC respondents were general internal medicine physicians. CONCLUSIONS: Most DPC practices no longer submit to insurance and are family medicine trained. Compared with the previous sampling, DPC practices report decreased membership fees and increased projected panel size. These trends may signify the DPC movement's growth in application and scope.

Infant Mortality and SIDS Perceptions Among Key Healthcare Professional Informants in Sedgwick County, KS.

INTRODUCTION: Sedgwick County, KS, has one of the highest infant mortality rates (IMR) in the USA, of which sudden infant death syndrome (SIDS) is a large component. The purpose of this study was to assess local key informants' awareness of the high IMR overall, their knowledge and beliefs about SIDS risk factors specifically, and their recommendations for ways to increase physician and community awareness of SIDS within Sedgwick County, KS. METHODS: Structured interviews were conducted with key informants from Sedgwick County, KS. RESULTS: Four themes emerged from key informant interviews: low level of awareness of infant mortality and SIDS, target population most at risk for SIDS/infant mortality, and barriers to and importance of SIDS education. Key informants were in consensus that there was a lack of general community awareness surrounding the high IMR in Sedgwick County. Strategies were identified to address this issue, including consistent SIDS education of medical providers and parents, social support to moms, use of social media, and involving the faith community in educating target populations about risk factors. CONCLUSIONS: Health and public health key informants provided an overall view of their perception of the SIDS problem in Sedgwick County, KS. Based on collected interviews, the consensus was there are significant problems within Sedgwick County around the issue of SIDS awareness (severity of the problem), SIDS risk, and barriers to increasing SIDS education among professional and community members. African-Americans were identified as the population with the highest infant mortality and SIDS rates in Sedgwick County by health and public health key informant participants. A concerted, educational approach was recommended as the best way forward to reduce SIDS risk within this community.

Effect of fluoroscopic X-ray beam spectrum on air-kerma measurement accuracy: implications for establishing correction coefficients on interventional fluoroscopes with KAP meters.

The first goal of this study was to investigate the accuracy of the displayed reference plane air kerma (Ka,r) or air kerma-area product (Pk,a) over a broad spectrum of X-ray beam qualities on clinically used interventional fluoroscopes incorporating air kerma-area product meters (KAP meters) to measure X-ray output. The second goal was to investigate the accuracy of a correction coefficient (CC) determined at a single beam quality and applied to the measured Ka,r over a broad spectrum of beam qualities. Eleven state-of-the-art interventional fluoroscopes were evaluated, consisting of eight Siemens Artis zee and Artis Q systems and three Philips Allura FD systems. A separate calibrated 60 cc ionization chamber (external chamber) was used to determine the accuracy of the KAP meter over a broad range of clinically used beam qualities. For typical adult beam qualities, applying a single CC deter-mined at 100 kVp with copper (Cu) in the beam resulted in a deviation of < 5% due to beam quality variation. This result indicates that applying a CC determined using The American Association of Physicists in Medicine Task Group 190 protocol or a similar protocol provides very good accuracy as compared to the allowed ± 35% deviation of the KAP meter in this limited beam quality range. For interventional fluoroscopes dedicated to or routinely used to perform pediatric interventions, using a CC established with a low kVp (~ 55-60 kVp) and large amount of Cu filtration (~ 0.6-0.9 mm) may result in greater accuracy as compared to using the 100 kVp values. KAP meter responses indicate that fluoroscope vendors are likely normalizing or otherwise influencing the KAP meter output data. Although this may provide improved accuracy in some instances, there is the potential for large discrete errors to occur, and these errors may be difficult to identify.

Imaging of Arthroplasties: Improved Image Quality and Lesion Detection With Iterative Metal Artifact Reduction, a New CT Metal Artifact Reduction Technique.

OBJECTIVE: The purpose of this study was to compare iterative metal artifact reduction (iMAR), a new single-energy metal artifact reduction technique, with filtered back projection (FBP) in terms of attenuation values, qualitative image quality, and streak artifacts near shoulder and hip arthroplasties and observer ability with these techniques to detect pathologic lesions near an arthroplasty in a phantom model. MATERIALS AND METHODS: Preoperative and postoperative CT scans of 40 shoulder and 21 hip arthroplasties were reviewed. All postoperative scans were obtained using the same technique (140 kVp, 300 quality reference mAs, 128 × 0.6 mm detector collimation) on one of three CT scanners and reconstructed with FBP and iMAR. The attenuation differences in bones and soft tissues between preoperative and postoperative scans at the same location were compared; image quality and streak artifact for both reconstructions were qualitatively graded by two blinded readers. Observer ability and confidence to detect lesions near an arthroplasty in a phantom model were graded. RESULTS: For both readers, iMAR had more accurate attenuation values (p < 0.001), qualitatively better image quality (p < 0.001), and less streak artifact (p < 0.001) in all locations near arthroplasties compared with FBP. Both readers detected more lesions (p ≤ 0.04) with higher confidence (p ≤ 0.01) with iMAR than with FBP in the phantom model. CONCLUSION: The iMAR technique provided more accurate attenuation values, better image quality, and less streak artifact near hip and shoulder arthroplasties than FBP; iMAR also increased observer ability and confidence to detect pathologic lesions near arthroplasties in a phantom model.

The Effect of Implementing Gene Expression Classifier on Outcomes of Thyroid Nodules with Indeterminate Cytology.

Thyroid nodules are classified into six cytological categories under the Bethesda classification system. Two of these categories, atypical of undetermined significance (AUS) and suspicious for a follicular neoplasm (SFN), are further labeled as "indeterminate" diagnosis. Starting in June, 2012, Kansas University-Wichita Endocrine clinic implemented Afirma® Gene Expression Classifier (AGEC) to evaluate the need for surgical resection of thyroid nodules in patients with an indeterminate diagnosis. Electronic medical records of patients who underwent thyroid nodule fine-needle aspiration from 2004-2014 were reviewed. The aim of this study was to find whether implementing AGEC was associated with decreased surgical recommendation rate, decreased cost, and increased incidence of thyroid malignancy diagnosed by surgery in patients with indeterminate diagnosis. A total of 299 consecutive patients' charts were screened. Sixty-one (20 %) patients had an indeterminate diagnosis. Out of these, 27 (44 %) patients underwent evaluation before and 34 (56 %) patients underwent evaluation after AGEC implementation, respectively. Surgical recommendation for patients with indeterminate finding decreased from 81.5 to 50 % (p = 0.01) after AGEC implementation. Surgical pathology was read as malignant in 20 and 85.7 % (p < 0.01) of patients before and after AGEC implementation, respectively. Primary cost-benefit estimate showed implementing AGEC has saved $1048/patient in medical evaluation and initial management of patients with indeterminate diagnosis. AGEC implementation has decreased the number of surgical recommendations, has lowered financial burden, and has increased incidence of thyroid malignancy diagnosed by surgical pathology in patients with indeterminate diagnosis of thyroid nodules.

Image Noise, CNR, and Detectability of Low-Contrast, Low-Attenuation Liver Lesions in a Phantom: Effects of Radiation Exposure, Phantom Size, Integrated Circuit Detector, and Iterative Reconstruction.

Purpose To assess image noise, contrast-to-noise ratio (CNR) and detectability of low-contrast, low-attenuation liver lesions in a semianthropomorphic phantom by using either a discrete circuit (DC) detector and filtered back projection (FBP) or an integrated circuit (IC) detector and iterative reconstruction (IR) with changes in radiation exposure and phantom size. Materials and Methods An anthropomorphic phantom without or with a 5-cm-thick fat-mimicking ring (widths, 30 and 40 cm) containing liver inserts with four spherical lesions was scanned with five exposure settings on each of two computed tomography scanners, one equipped with a DC detector and the other with an IC detector. Images from the DC and IC detector scanners were reconstructed with FBP and IR, respectively. Image noise and lesion CNR were measured. Four radiologists evaluated lesion presence on a five-point diagnostic confidence scale. Data analyses included receiver operating characteristic (ROC) curve analysis and noninferiority analysis. Results The combination of IC and IR significantly reduced image noise (P < .001) (with the greatest reduction in the 40-cm phantom and at lower exposures) and improved lesion CNR (P < .001). There was no significant difference in area under the ROC curve between detector-reconstruction combinations at fixed exposure for either phantom. Reader accuracy with IC-IR was noninferior at 50% (100 mAs [effective]) and 25% (300 mAs [effective]) exposure reduction for the 30- and 40-cm phantoms, respectively (adjusted P < .001 and .04 respectively). IC-IR improved readers' confidence in the presence of a lesion (P = .029) independent of phantom size or exposure level. Conclusion IC-IR improved objective image quality and lesion detection confidence but did not result in superior diagnostic accuracy when compared with DC-FBP. Moderate exposure reductions maintained comparable diagnostic accuracy for both detector-reconstruction combinations. Lesion detection in the 40-cm phantom was inferior at smaller exposure reduction than in the 30-cm phantom. (©) RSNA, 2016 Online supplemental material is available for this article.

Approaches to interventional fluoroscopic dose curves.

Modern fluoroscopes used for image-based guidance in interventional procedures are complex X-ray machines, with advanced image acquisition and processing systems capable of automatically controlling numerous parameters based on defined protocol settings. This study evaluated and compared approaches to technique factor modulation and air kerma rates in response to simulated patient thickness variations for four state-of-the-art and one previous-generation interventional fluoroscopes. A polymethyl methacrylate (PMMA) phantom was used as a tissue surrogate for the purposes of determining fluoroscopic reference plane air kerma rates, kVp, mA, and variable copper filter thickness over a wide range of simulated tissue thicknesses. Data were acquired for each fluoroscopic and acquisition dose curve within each vendor's default abdomen or body imaging protocol. The data obtained indicated vendor- and model-specific variations in the approach to technique factor modulation and reference plane air kerma rates across a range of tissue thicknesses. However, in the imaging protocol evaluated, all of the state-of-the-art systems had relatively low air kerma rates in the fluoroscopic low-dose imaging mode as compared to the previous-generation unit. Each of the newest-generation systems also employ Cu filtration within the selected protocol in the acquisition mode of imaging; this is a substantial benefit, reducing the skin entrance dose to the patient in the highest dose-rate mode of fluoroscope operation. Some vendors have also enhanced the radiation output capabilities of their fluoroscopes which, under specific conditions, may be beneficial; however, these increased output capabilities also have the potential to lead to unnecessarily high dose rates. Understanding how fluoroscopic technique factors are modulated provides insight into the vendor-specific image acquisition approach and may provide opportunities to optimize the imaging protocols for clinical practice.

Clergy Wellness: An Assessment of Perceived Barriers to Achieving Healthier Lifestyles.

This study sought to obtain a better understanding of how clergy view their health and to investigate their self-reported health status. Additionally, this study sought to explore personal and professional barriers among clergy to living a healthier life. An electronic 32-item survey was sent to all practicing clergy in Kansas East and West conferences of United Methodist church by the Kansas Area Office of the United Methodist Church. Survey items included participants' demographic information and health conditions (e.g., diabetes, heart disease, high blood pressure, high cholesterol). The self-reported general health, mental health, and physical health data were also collected to compare to the general population in Kansas. Clergy were also asked to identify perceived barriers to health. A total of 150 clergy participated in the survey. The majority (93.7 %) self-reported their health as good, very good, or excellent. Participating clergy self-reported a higher prevalence of chronic diseases (diabetes, heart disease, high blood pressure, and high cholesterol) than the Kansas general population, but those differences were not statistically significant. More than three-fourths (77.4 %) of the participating clergy reported weights and heights that classified them as either overweight or obese. Lack of family time was the most frequently reported personal barrier to achieving a healthier lifestyle. An unpredictable work schedule was reported as the most frequent professional barrier to achieving a healthier lifestyle. This study suggests that Kansas clergy generally view their overall health status favorably despite being overweight or obese. Clergy also self-reported higher prevalence of chronic diseases than the general Kansas population, though the prevalence was not statistically different. This study provides additional insight into clergy health and offers suggestions to address the barriers preventing clergy from working toward better health.

Adult abdomen-pelvis CT: Does equilibrium dose-pitch product better account for the kVp dependence of organ dose than conventional CTDI?

PURPOSE: In CT imaging, a desirable quality assurance dose quantity should account for the dose variability across scan parameters and scanner models. Recently, AAPM Task Group 111 proposed to use equilibrium dose-pitch product (Dˆeq), in place of CT dose index (CTDI100), for scan modes involving table translation. The purpose of this work is to investigate whether this new concept better accounts for the tube voltage (kVp) dependence of organ dose than the conventional CTDI100. METHODS: Three extended cardiac-torso patient models were included in this study. They represented normal-weight, overweight, and obese patients with abdomen-pelvis diameters ranging between 23 and 36 cm and body mass indices ranging between 20 and 42. A Monte Carlo program developed and validated for a 128-slice CT system was used to simulate organ dose for abdomen-pelvis scans at five tube voltages (70, 80, 100, 120, 140 kVp) with a pitch of 0.8 and a collimation of 38.4 mm. The same Monte Carlo program was also used to obtain CTDI100 and Dˆeq as well as their volume-averaged values, CTDIvol and Dˆeq,vol. RESULTS: With other scan parameters kept constant, organ dose itself depended strongly on kVp. For the normal-weight patient model, the coefficient of variation (COV) across the five kVp values ranged between 72% and 75% for nine organs (liver, spleen, stomach, pancreas, kidneys, colon, small intestine, bladder, and ovaries) fully encompassed by the primary radiation beam. The COV generally increased with increasing patient size, ranging between 72%-77% and 76%-81% for the overweight and obese patient models, respectively. One-way analysis of variance for the effect of kVp was highly significant for all patient models (p<2×10(-26)). When organ dose was normalized by CTDIvol, the COV across kVps reduced to 5%-11%, 6%-15%, 12%-22% for the normal-weight, overweight, and obese patients, respectively. The effect of kVp was still highly significant (p=0.0001-0.004). When organ dose was normalized by Dˆeq,vol, the COV further reduced to 1%-8%, 3%-11%, 9%-19%, respectively. The effect of kVp was still significant for the obese patient model (p=0.004), but no longer significant for the normal-weight and overweight patient models (p=0.4 and 0.09, respectively). Finally, if organ dose conversion factors obtained at 120 kVp were used to approximate the values at 70 and 80 kVp, the resulting errors in the estimated organ dose were significantly reduced when the conversion factors were based on Dˆeq,vol instead of CTDIvol. CONCLUSIONS: In adult abdomen-pelvis CT, equilibrium dose-pitch product better accounts for the kVp dependence of organ dose than CTDI100.