Welcome to the UA Campus Repository, a service of the University of Arizona Libraries. The repository shares, archives and preserves unique digital materials from faculty, staff, students and affiliated contributors. Contact us at repository@u.library.arizona.edu with any questions.

 

Featured submissions

June 2022

May 2022

April 2022

 

See more featured submissions

  • Burnout and work-work imbalance in radiology- wicked problems on a global scale. A baseline pre-COVID-19 survey of US neuroradiologists compared to international radiologists and adjacent staff

    Chen, James Y.; Vedantham, Srinivasan; Lexa, Frank J.; University of Arizona (Elsevier BV, 2022-01)
    Purpose: Worldwide, radiologists are experiencing increasing clinical workloads with associated increased burnout. This paper will review burnout definitions, prevalence, and causes. We will also share data from a survey of US neuroradiologists as an example of the impact of work-work imbalances from clinical overload. This article examines the impact on several key job indicators and upon the quality of the neuroradiology work environment in one nation. Finally, we will review proposals for ameliorating and preventing radiologist burnout. Method: A survey was sent to members of the American Society of Neuroradiology (ASNR) practicing in the US. Selected measures included workhours and volume, burnout symptoms, subjectively reported errors, participation in non-clinical activities, perceived interpretation quality, results communication, and consideration of early retirement. Results: Survey respondents (n = 412) included 57.5% with teaching responsibilities. Cutbacks in teaching, mentoring, research and/or practice building were reported by 86.2% of respondents. Subjective errors were reported as occurring sometimes or more frequently in the majority of respondents (56.9%) and were increased with faster than optimal speeds of interpretation (P < 0.001) and signing (P < 0.001). At least one burnout measure was reported by 85.2% of respondents. Conclusions: Increasing clinical demands in conjunction with a more challenging work environment impacts the ability of radiologists to perform core non-interpretive duties that are critical for success in both private and academic practice and is associated with burnout symptoms and adverse effects on quality. While this survey does not prove causation, the trends and findings are concerning and warrant both close monitoring and appropriate intervention.
  • Cone-beam breast CT using an offset detector: effect of detector offset and image reconstruction algorithm

    Tseng, Hsin Wu; Karellas, Andrew; Vedantham, Srinivasan; Department of Medical Imaging, The University of Arizona; Department of Biomedical Engineering, The University of Arizona (IOP Publishing, 2022-04-07)
    Objective. A dedicated cone-beam breast computed tomography (BCT) using a high-resolution, low-noise detector operating in offset-detector geometry has been developed. This study investigates the effects of varying detector offsets and image reconstruction algorithms to determine the appropriate combination of detector offset and reconstruction algorithm. Approach. Projection datasets (300 projections in 360°) of 30 breasts containing calcified lesions that were acquired using a prototype cone-beam BCT system comprising a 40 × 30 cm flat-panel detector with 1024 × 768 detector pixels were reconstructed using Feldkamp-Davis-Kress (FDK) algorithm and served as the reference. The projection datasets were retrospectively truncated to emulate cone-beam datasets with sinograms of 768 × 768 and 640 × 768 detector pixels, corresponding to 5 cm and 7.5 cm lateral offsets, respectively. These datasets were reconstructed using the FDK algorithm with appropriate weights and an ASD-POCS-based Fast, total variation-Regularized, Iterative, Statistical reconstruction Technique (FRIST), resulting in a total of 4 offset-detector reconstructions (2 detector offsets × 2 reconstruction methods). Signal difference-to-noise ratio (SDNR), variance, and full-width at half-maximum (FWHM) of calcifications in two orthogonal directions were determined from all reconstructions. All quantitative measurements were performed on images in units of linear attenuation coefficient (1/cm). Results. The FWHM of calcifications did not differ (P > 0.262) among reconstruction algorithms and detector formats, implying comparable spatial resolution. For a chosen detector offset, the FRIST algorithm outperformed FDK in terms of variance and SDNR (P < 0.0001). For a given reconstruction method, the 5 cm offset provided better results. Significance. This study indicates the feasibility of using the compressed sensing-based, FRIST algorithm to reconstruct sinograms from offset-detectors. Among the reconstruction methods and detector offsets studied, FRIST reconstructions corresponding to a 30 cm × 30 cm with 5 cm lateral offset, achieved the best performance. A clinical prototype using such an offset geometry has been developed and installed for clinical trials.
  • X-ray dosimetry in breast cancer screening: 2D and 3D mammography

    Di Maria, S; Vedantham, S; Vaz, P; Department of Medical Imaging, The University of Arizona (Elsevier Ireland Ltd, 2022-03-29)
    According to the World Health Organization (WHO), at the end of 2020, 7.8 million women alive were diagnosed with breast cancer in the past 5 years, making it the world's most prevalent cancer. It is largely recognized and demonstrated that early detection represents the first strategy to follow in the fight against cancer. The effectiveness of mammography screening for early breast cancer detection has been proven in several surveys and studies over the last three decades. The estimation of the Mean Glandular Dose (MGD) is important to understand the radiation-associated risk from breast x-ray imaging exams. It continues to be the subject of numerous studies and debates, since its accuracy is directly related to risk estimation and for optimizing breast cancer screening programs. This manuscript reviews the main dosimetry formalisms used to estimate the MGD in mammography and to understand the continuing efforts to reduce the absorbed dose over the last forty years. The dosimetry protocols were formulated initially for mammography. Digital breast tomosynthesis (DBT) either in conjunction with synthesized digital mammogram (SDM) or with digital mammography (DM), is routinely used in many breast cancer screening programs and consequently the dosimetry protocols were extended for these techniques.
  • Mechanical behavior of additively manufactured GRCop-84 copper alloy lattice structures

    Hazeli, Kavan; June, Daniel; Anantwar, Prathmesh; Babamiri, Behzad Bahrami; Aerospace and Mechanical Engineering Department, The University of Arizona (Elsevier BV, 2022-08)
    This study investigates the interplay between microstructure, topology and their combined effect on the quasi-static and dynamic behavior of additively manufactured Copper–Chromium–Niobium alloy (GRCop-84) lattice structures. Lattice structures made of GRCop-84 alloys are beneficial for wide range of applications due to the combination of the high strength and thermal conductivity imparted by GRCop-84 while minimizing weight and increasing the energy absorption through the use of the lattice structure. X-ray computed tomography (XCT) and optical microscopy were used to characterize the porosity and grain structure, respectively. Quasi-static and dynamic testing was performed on the as-built (AB) samples at strain rates of 10−1s−1 and 103s−1, respectively. The observations indicated that reducing the unit cell size from 4mm to 2mm led to a 66% reduction in porosity. Depending on the topology of the tested sample, the reduced porosity within the 2mm unit cell samples resulted in a 35% to 60% increase in the compressive yield strength. To understand whether topology is the only driving mechanism that influence the mechanical properties e.g., yield strength, the microstructure was altered through hot isostatic pressing (HIP) heat treatment while the topology was kept constant. It was noted that the 4mm unit cell size was more responsive to HIPing with a 40% reduction in porosity, while the 2mm unit cell size only experienced a 28% reduction in porosity. It was also noticed that there was a 48% reduction in porosity by minimizing the unit cell size from 4mm to 2mm in the case of the HIPed samples. Using this data, a correlation was recognized between microstructure and topology. It was found that HIPed samples experienced more plastic deformation and exhibited stress plateau that is common in cellular solids, indicating improved energy absorbing abilities compared to AB. AB Samples demonstrated higher compressive strength and failed due to the brittle nature of the AB microstructure. Lattice Structures with unit cell sizes of 4mm and 2mm experienced different collapse mechanisms, with 2mm unit cell lattices being topology dependent and 4mm unit cell lattices dependent on microstructure.
  • Learning a typologically unusual reduplication pattern: An artificial language learning study of base-dependent reduplication

    Haugen, Jason D.; Ussishkin, Adam; Dawson, Colin Reimer; Department of Linguistics, University of Arizona (Springer Science and Business Media LLC, 2022-05-31)
    We report on an artificial language learning experiment testing the learnability of a typologically rare pattern of reduplication. Our model comes from syllable-copy reduplication in Hiaki (aka Yaqui, Uto-Aztecan), a base-dependent pattern wherein the shape of reduplication depends crucially on syllabification in the base: coda consonants can copy in reduplication if and only if there is a corresponding coda in the base. Using a controlled artificial language experiment with a forced-choice paradigm, we show that native English speakers who have no prior exposure to any language with a grammar employing syllable-copy reduplication are in many cases able to learn a variable CV or CVC syllable-copying rule as measured by eventual above-chance selection of the correct form. However, compared to participants learning either a consistent CV or CVC copying rule, the performance of participants tasked with learning such a variable syllable-copying rule improves more slowly, and these participants make more errors overall. We suggest that this difference in learnability may be one of a number of factors helping to explain the typological rarity of certain morphological patterns.

View more