Substantial decreases in the growth of outpatient CT and US procedure volume coincident with ROE implementation (supplemented by DS for CT) were observed. The utilization of outpatient MR imaging decreased less impressively, with only the rate of growth being significantly lower after interventions were in effect.

ObjectiveTo assess effects of off-centering, automatic exposure control, and padding on attenuation values, noise, and radiation dose when using in-plane bismuth-based shields for CT scanning.Materials and MethodsA 30 cm anthropomorphic chest phantom was scanned on a 64-multidetector CT, with the center of the phantom aligned to the gantry isocenter. Scanning was repeated after placing a bismuth breast shield on the anterior surface with no gap and with 1, 2, and 6 cm of padding between the shield and the phantom surface. The "shielded" phantom was also scanned with combined modulation and off-centering of the phantom at 2 cm, 4 cm and 6 cm below the gantry isocenter. CT numbers, noise, and surface radiation dose were measured. The data were analyzed using an analysis of variance.ResultsThe in-plane shield was not associated with any significant increment for the surface dose or CT dose index volume, which was achieved by comparing the radiation dose measured by combined modulation technique to the fixed mAs (p > 0.05). Irrespective of the gap or the surface CT numbers, surface noise increased to a larger extent compared to Hounsfield unit (HU) (0-6 cm, 26-55%) and noise (0-6 cm, 30-40%) in the center. With off-centering, in-plane shielding devices are associated with less dose savings, although dose reduction was still higher than in the absence of shielding (0 cm off-center, 90% dose reduction; 2 cm, 61%) (p < 0.0001). Streak artifacts were noted at 0 cm and 1 cm gaps but not at 2 cm and 6 cm gaps of shielding to the surface distances.ConclusionIn-plane shields are associated with greater image noise, artifactually increased attenuation values, and streak artifacts. However, shields reduce radiation dose regardless of the extent of off-centering. Automatic exposure control did not increase radiation dose when using a shield.

ObjectiveTo compare the interpretation times between conventional screening mammography and screening combined tomosynthesis and conventional 2D mammography in a large academic center with multiple participating radiologists with a wide range of experience for determining the effect of implementing a screening tomosynthesis program. Materials and MethodsImages from 3665 examinations (1502 combined and 2163 digital mammography) from July 2012 to January 2013 were prospectively read by 10 radiologists from screening mammography or screening combined tomosynthesis conventional 2D mammography in at least five sessions per radiologist per modality (each session was 1-hour-long uninterrupted time). The number of cases reported for each reader during each session was recorded and the experience level for each radiologist was also correlated to the average number of cases reported per hour. Statistical analysis was used to assess the number of studies interpreted per hour and to evaluate correlation between breast imaging experience and time taken to interpret images from both modalities. ResultsApproximately 24 studies were interpreted per hour for combined tomosynthesis and mammography and 34 for digital mammography alone. The mean interpretation time for combined tomosynthesis and mammography was 47% longer than that for digital mammography. The overall interpretation time for combined tomosynthesis and mammography examinations decreased with the increase in years of breast imaging experience. ConclusionThe mean interpretation time for combined tomosynthesis and mammography was longer than that for digital mammography by 47% and the overall interpretation time decreased with increase in years of breast imaging experience. This increase in interpretation time may be within acceptable limits, given the technology has other associated benefits, such as increased cancer detection, reduced false-positive rates, and streamlined diagnostic workflow.

Purpose To determine whether the rates and tumor characteristics of screening-detected and interval cancers differ for two-dimensional digital mammography (DM) versus digital breast tomosynthesis (DBT) mammography. Materials and Methods Consecutive screening mammograms from January 2009 to February 2011 (DM group, before DBT integration) and from January 2013 to February 2015 (DBT group, after complete DBT integration) were reviewed. Cancers were considered screening detected if diagnosed within 365 days of a positive screening examination and interval if diagnosed within 365 days of a negative screening examination. Z tests were used to compare cancers on DM versus DBT examinations. Results A total of 948 breast cancers were diagnosed after 78 385 DM and 76 896 DBT examinations. Although the overall rate of screening-detected cancers was similar with DM and DBT (5.0 vs 5.0 per 1000 examinations, P = .98), a higher proportion of screening-detected cancers were invasive rather than in situ with DBT (74.2% [287 of 387] vs 66.0% [260 of 394], P = .01). There were no significant differences in tumor characteristics, including size at pathologic examination, grade, hormone receptor status, and nodal status, between the screening-detected invasive cancers on DM versus DBT (P = .09-.99). The rate of interval cancers was similar with DM and DBT (1.1 vs 1.1 per 1000 examinations, P = .84). Compared with symptomatic interval cancers, magnetic resonance imaging-detected interval cancers were more likely to be minimal cancers. Conclusion The overall rates of screening-detected and interval cancers are similar with DM and DBT, but a higher proportion of screening-detected cancers are invasive rather than in situ with DBT. RSNA, 2017.

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