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1.
J Appl Clin Med Phys ; 24(11): e14164, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37787494

RESUMO

The American Association of Physicists in Medicine began the Medical Physics Leadership Academy Journal Club in the fall of 2020. The initiative was launched to provide a forum for medical physicists to learn about leadership topics using published material, discuss and reflect on the material, and consider incorporating the discussed skills into their professional practice. This report presents the framework for the MPLA Journal Club program, describes the lessons learned over the last 2 years, summarizes the data collected from attendees, and highlights the roadmap for the program moving forward.


Assuntos
Liderança , Física , Humanos , Estados Unidos
2.
AJR Am J Roentgenol ; 216(3): 824-834, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33474986

RESUMO

OBJECTIVE. The purpose of this study is to comprehensively implement a patient-informed organ dose monitoring framework for clinical CT and compare the effective dose (ED) according to the patient-informed organ dose with ED according to the dose-length product (DLP) in 1048 patients. MATERIALS AND METHODS. Organ doses for a given examination are computed by matching the topogram to a computational phantom from a library of anthropomorphic phantoms and scaling the fixed tube current dose coefficients by the examination volume CT dose index (CTDIvol) and the tube-current modulation using a previously validated convolution-based technique. In this study, the library was expanded to 58 adult, 56 pediatric, five pregnant, and 12 International Commission on Radiological Protection (ICRP) reference models, and the technique was extended to include multiple protocols, a bias correction, and uncertainty estimates. The method was implemented in a clinical monitoring system to estimate organ dose and organ dose-based ED for 647 abdomen-pelvis and 401 chest examinations, which were compared with DLP-based ED using a t test. RESULTS. For the majority of the organs, the maximum errors in organ dose estimation were 18% and 8%, averaged across all protocols, without and with bias correction, respectively. For the patient examinations, DLP-based ED was significantly different from organ dose-based ED by as much as 190.9% and 234.7% for chest and abdomen-pelvis scans, respectively (mean, 9.0% and 24.3%). The differences were statistically significant (p < .001) and exhibited overestimation for larger-sized patients and underestimation for smaller-sized patients. CONCLUSION. A patient-informed organ dose estimation framework was comprehensively implemented applicable to clinical imaging of adult, pediatric, and pregnant patients. Compared with organ dose-based ED, DLP-based ED may overestimate effective dose for larger-sized patients and underestimate it for smaller-sized patients.


Assuntos
Doses de Radiação , Monitoramento de Radiação/métodos , Tomografia Computadorizada por Raios X , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Pontos de Referência Anatômicos/diagnóstico por imagem , Tamanho Corporal , Osso e Ossos/diagnóstico por imagem , Criança , Feminino , Idade Gestacional , Humanos , Fígado/diagnóstico por imagem , Pulmão/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Pelve/diagnóstico por imagem , Imagens de Fantasmas , Gravidez , Padrões de Referência , Estudos Retrospectivos , Fluxo de Trabalho , Adulto Jovem
3.
J Shoulder Elbow Surg ; 29(3): 491-496, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31519425

RESUMO

HYPOTHESIS: The purpose of this study was to evaluate the association between smoking and postoperative complications following total shoulder arthroplasty. We hypothesized that active smokers would have significantly greater postoperative medical and surgical complications. METHODS: The American College of Surgeons National Surgical Quality Improvement Program database was queried for patients who underwent total shoulder arthroplasties from 2005 through 2016. Patients were stratified based on tobacco use within the past year. Logistic regression was used to assess the relationship between smoking status and postoperative medical and surgical complications. Multivariate logistic regression was used to adjust for demographic and comorbid factors. RESULTS: We identified 14,465 patients, of whom 10.5% were active smokers. Smokers were more likely to be younger, to be female patients, and to have a lower body mass index compared with nonsmokers (P < .001). Univariate analysis demonstrated that smoking was not associated with postoperative medical complications (P > .05) but was associated with an increased risk of overall surgical complications (odds ratio [OR], 3.259; 95% confidence interval [CI], 1.861-5.709; P < .001). Multivariate modeling showed that smoking increased the risk of wound complications (adjusted OR, 7.564; 95% CI, 2.128-26.889; P = .002) and surgical-site infections (adjusted OR, 1.927; 95% CI, 1.023-3.630; P = .042). DISCUSSION AND CONCLUSION: This study demonstrates that smoking is associated with an increased risk of surgical complications following total shoulder arthroplasty. On the basis of our available data, medical complications are not significantly increased. This information can help risk stratify patients prior to their procedures.


Assuntos
Artroplastia do Ombro/efeitos adversos , Fumar/efeitos adversos , Deiscência da Ferida Operatória/epidemiologia , Infecção da Ferida Cirúrgica/epidemiologia , Idoso , Estudos de Coortes , Bases de Dados Factuais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Estudos Retrospectivos , Estados Unidos/epidemiologia
4.
Phys Rev Lett ; 122(1): 013402, 2019 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-31012724

RESUMO

We study the loss of atoms in quantum Newton's cradles with a range of average energies and transverse confinements. We find that the three-body collision rate in one-dimension is strongly energy dependent, as predicted by a strictly 1D theory. We adapt the theory to atoms in waveguides, then, using detailed momentum measurements to infer all the collisions that occur, we compare the observed loss to the adapted theory and find that they agree well.

5.
AJR Am J Roentgenol ; 213(4): 889-894, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31180737

RESUMO

OBJECTIVE. Diagnostic reference levels were developed as guidance for radiation dose in medical imaging and, by inference, diagnostic quality. The objective of this work was to expand the concept of diagnostic reference levels to explicitly include noise of CT examinations to simultaneously target both dose and quality through corresponding reference values. MATERIALS AND METHODS. The study consisted of 2851 adult CT examinations performed with scanners from two manufacturers and two clinical protocols: abdominopelvic CT with IV contrast administration and chest CT without IV contrast administration. An institutional informatics system was used to automatically extract protocol type, patient diameter, volume CT dose index, and noise magnitude from images. The data were divided into five reference patient size ranges. Noise reference level, noise reference range, dose reference level, and dose reference range were defined for each size range. RESULTS. The data exhibited strong dependence between dose and patient size, weak dependence between noise and patient size, and different trends for different manufacturers with differing strategies for tube current modulation. The results suggest size-based reference intervals and levels for noise and dose (e.g., noise reference level and noise reference range of 11.5-12.9 HU and 11.0-14.0 HU for chest CT and 10.1-12.1 HU and 9.4-13.7 HU for abdominopelvic CT examinations) that can be targeted to improve clinical performance consistency. CONCLUSION. New reference levels and ranges, which simultaneously consider image noise and radiation dose information across wide patient populations, were defined and determined for two clinical protocols. The methods of new quantitative constraints may provide unique and useful information about the goal of managing the variability of image quality and dose in clinical CT examinations.


Assuntos
Ruído , Doses de Radiação , Tomografia Computadorizada por Raios X/normas , Adulto , Tamanho Corporal , Meios de Contraste , Humanos , Radiografia Abdominal/normas , Radiografia Torácica/normas , Valores de Referência
6.
AJR Am J Roentgenol ; 208(6): 1285-1296, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28350484

RESUMO

OBJECTIVE: The purpose of this study was to conduct longitudinal analyses of radiation dose data from adult patients undergoing clinically indicated, repeat identical thoracoabdominal CT examinations. MATERIALS AND METHODS: Radiation dose data were electronically collected from 2851 subjects undergoing 12,635 repeat identical CT scans (mean number of scans per patient, 4.8; range, 2-33) in one health system. Included CT protocols were chest-abdomen-pelvis with contrast administration (n = 4621 CT studies of 1064 patients), abdomen-pelvis with contrast administration (n = 876 CT studies of 261 patients), renal stone (n = 1053 CT studies of 380 patients), and chest (n = 6085 CT studies of 1146 patients) without contrast administration. A radiation-tracking software infrastructure was adopted to extract data from DICOM headers in PACS. Size-specific dose estimate (SSDE) was calculated. RESULTS: A trend was observed toward global reduction in SSDE values with all protocols investigated (chest-abdomen-pelvis slope, -1.78; abdomen-pelvis slope, -0.82; renal stone slope, -0.83; chest slope, -0.47; p < 0.001 for all comparisons). The intraindividual analyses of radiation dose distribution showed widespread variability in SSDE values across the four protocols investigated (chest-abdomen-pelvis mean coefficient of variance, 14.02 mGy; abdomen-pelvis mean coefficient of variance, 10.26 mGy; renal stone mean coefficient of variance, 34.18 mGy; chest mean coefficient of variance, 6.74 mGy). CONCLUSION: Although there is a trend toward global reduction in radiation doses, this study showed widespread variability in the radiation dose that each patient undergoing identical repeat thoracoabdominal CT protocols absorbs. These data may provide a foundation for the future development of best-practice guidelines for patient-specific radiation dose monitoring.


Assuntos
Centros Médicos Acadêmicos/estatística & dados numéricos , Doses de Radiação , Exposição à Radiação/estatística & dados numéricos , Radiografia Abdominal/estatística & dados numéricos , Radiografia Torácica/estatística & dados numéricos , Tomografia Computadorizada por Raios X/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , North Carolina/epidemiologia , Radiometria/estatística & dados numéricos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Adulto Jovem
7.
Radiology ; 279(1): 269-77, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26536403

RESUMO

PURPOSE: To determine the variance in virtual monochromatic computed tomography (CT) numbers from the same lesion, comparing the two clinically available dual-energy multidetector CT hardware implementations (single-source projection-based and dual-source image-based), in a phantom-based simulated abdominal environment. MATERIALS AND METHODS: This phantom-based study was exempt from institutional review board oversight. Polyethylene terephthalate spheres (15 and 18 mm) with two iodine-to-saline dilutions (0.8 and 1.2 mg of iodine per millilliter) were serially suspended in a cylindrical polypropylene bottle filled with diluted iodinated contrast material. The bottle was placed into a 36-cm-wide torso-shaped water phantom simulating the abdomen of a medium-sized patient. Dual-energy (80/140 kVp) and single-energy (100 and 120 kVp) scans were obtained with single-source and dual-source multidetector CT implementations. Virtual monochromatic images were reconstructed at energy levels of 40-140 keV (in 10-keV increments) in either the projection-space or image-space domain. A multivariate regression analysis approach was used to investigate the effect of energy level, lesion size, lesion iodine content, and implementation type on measured CT numbers. RESULTS: There were significant differences in the attenuation values measured in the simulated lesions with the single-source projection-based platform and the dual-source image-based implementation (P < .001 for all comparisons). The magnitude of these differences was greatest at lower monochromatic energy levels and at lower iodine concentrations (average difference at 40 keV: 25.7 HU; average difference at 140 keV: 7 HU). The monochromatic energy level and the lesion iodine concentration had a significant effect on the difference in the measured attenuation values between the two implementations, which indicates that the two imaging platforms respond differently to changes in investigated variables (P < .001 for all comparisons). CONCLUSION: There is a statistically significant variance in virtual monochromatic CT numbers from the same lesion examined with single-source projection-based and dual-source image-based implementations. The magnitude of the variance is a function of the selected energy level and the lesion iodine content.


Assuntos
Tomografia Computadorizada Multidetectores/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Cor , Meios de Contraste , Humanos , Imagens de Fantasmas , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos
8.
Eur Radiol ; 26(1): 157-66, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25991484

RESUMO

OBJECTIVES: To assess the effect of automatic tube potential selection (ATPS) on radiation dose, image quality, and lesion detectability in paediatric abdominopelvic CT and CT angiography (CTA). METHODS: A paediatric modular phantom with contrast inserts was examined with routine pitch (1.4) and high pitch (3.0) using a standard abdominopelvic protocol with fixed 120 kVp, and ATPS with variable kVp in non-contrast, contrast-enhanced, and CTA mode. The volume CT dose index (CTDIvol), contrast-to-noise ratio (CNR) and lesion detectability index (d') were compared between the standard protocol and ATPS examinations. RESULTS: CTDIvol was reduced in all routine pitch ATPS examinations, with dose reductions of 27-52 % in CTA mode (P < 0.0001), 15-33 % in contrast-enhanced mode (P = 0.0003) and 8-14 % in non-contrast mode (P = 0.03). Iodine and soft tissue insert CNR and d' were improved or maintained in all ATPS examinations. kVp and dose were reduced in 25 % of high pitch ATPS examinations and in none of the full phantom examinations obtained after a single full phantom localizer. CONCLUSIONS: ATPS reduces radiation dose while maintaining image quality and lesion detectability in routine pitch paediatric abdominopelvic CT and CTA, but technical factors such as pitch and imaging range must be considered to optimize ATPS benefits. KEY POINTS: ATPS automatically individualizes CT scan technique for each patient. ATPS lowers radiation dose in routine pitch pediatric abdominopelvic CT and CTA. There is no loss of image quality or lesion detectability with ATPS. Pitch and scan range impact the effectiveness of ATPS dose reduction.


Assuntos
Angiografia/instrumentação , Pelve/diagnóstico por imagem , Imagens de Fantasmas , Radiografia Abdominal/instrumentação , Tomografia Computadorizada por Raios X/instrumentação , Abdome , Criança , Desenho de Equipamento , Humanos , Doses de Radiação
10.
Radiology ; 272(3): 895-902, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24814182

RESUMO

PURPOSE: To determine whether virtual monochromatic imaging from a dual-energy acquisition can improve patient-to-patient uniformity of aortic enhancement during multi-detector row computed tomographic (CT) angiography. MATERIALS AND METHODS: This retrospective single-center HIPAA-compliant study was approved by the institutional review board, with a waiver of informed consent. A proprietary tapered hollow phantom that contained a bone-mimicking insert and a hollow tube insert that mimicked the aorta was used. The aortic insert was filled with different iodine dilutions to mimic various degrees of enhancement. The phantom was imaged with both dual-energy and single-energy multi-detector row CT at four energy levels (80, 100, 120, and 140 kVp). Dual-energy multi-detector row CT was also performed in 62 patients (38 men; mean age, 60 years ± 12.7 [standard deviation]). For both the phantom and the patients, virtual monochromatic images were reconstructed from 40 to 140 keV, at 20-keV increments. The relationship between aortic attenuation and effective diameter was assessed by using a statistical model. RESULTS: For all polychromatic data sets, the mean aortic attenuation decreased proportionally to the effective diameter of the phantom (slope, ≥3.0 HU/cm). For virtual monochromatic data sets ranging from 80 to 140 keV, the regression slopes of aortic attenuation as a function of the phantom's effective diameter were negligible (slope, <1.0 HU/cm) for all iodine-to-water dilutions. In patients, the slope of the regression lines was also negligible (-0.69 < slope < 0.16) for virtual monochromatic data sets ranging from 100 to 140 keV. CONCLUSION: Within an energy range of 100-140 keV, virtual monochromatic images improve patient-to-patient uniformity of aortic enhancement compared with conventional polychromatic acquisitions.


Assuntos
Aorta Abdominal/diagnóstico por imagem , Aortografia/métodos , Intensificação de Imagem Radiográfica/métodos , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos , Tomografia Computadorizada por Raios X/métodos , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Estatísticos , Imagens de Fantasmas , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade
11.
Radiology ; 272(3): 767-76, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24844472

RESUMO

PURPOSE: To investigate whether dual-energy multi-detector row computed tomography (CT) with virtual monochromatic imaging can overcome renal cyst pseudoenhancement in a phantom experiment and a clinical study. MATERIALS AND METHODS: This retrospective single-center HIPAA-compliant study was approved by the institutional review board, with waiver of informed consent. Four renal compartments inserted into torso phantoms were filled with saline to simulate the unenhanced state and with iodinated solutions to simulate the three levels of renal parenchyma enhancement (140, 180, and 240 HU). Saline-filled spheres simulating renal cysts (15 and 18 mm in diameter) were serially suspended in the renal compartments and imaged with dual-energy and single-energy multi-detector row CT at four different energy levels (80, 100, 120, and 140 kVp). In addition, 28 patients (mean age, 66 years ± 10; mean body mass index, 31.3 kg/m(2) ± 6.2) with 34 intrarenal cysts were included. Virtual monochromatic images were reconstructed in 10-keV increments at energy levels ranging from 40 to 140 keV. Phantom and clinical data were analyzed by using multivariate regression analysis. RESULTS: In the phantom experiment, all polychromatic image data sets showed pseudoenhancement (postcontrast attenuation increase >10 HU) in all investigated conditions, with a significant effect on cyst size (P <.001), location (P <.001), and renal background attenuation level (P <.001). Virtual monochromatic images at energy levels ranging from 80 to 140 keV did not show pseudoenhancement, with the minimum attenuation increase (mean, 6.1 HU ± 1.6; range, 1.6-7.7 HU) on 80-keV images. In patients, pseudoenhancement never occurred on virtual monochromatic images at energy levels ranging from 90 to 140 keV. Patient body size had a significant effect (P = .007) on selection of the optimal monochromatic energy level. CONCLUSION: Dual-energy multi-detector row CT with reconstruction of virtual monochromatic images at an optimal energy level can overcome renal cyst pseudoenhancement.


Assuntos
Algoritmos , Doenças Renais Císticas/diagnóstico por imagem , Tomografia Computadorizada Multidetectores/métodos , Intensificação de Imagem Radiográfica/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Simulação por Computador , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Teóricos , Tomografia Computadorizada Multidetectores/instrumentação , Imagens de Fantasmas , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/instrumentação , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade
12.
AJR Am J Roentgenol ; 203(6): 1257-64, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25415703

RESUMO

OBJECTIVE: The purpose of this article is to investigate the effect of body size on the selection of optimal monochromatic energy level for maximizing the conspicuity of hypervascular liver tumors during late hepatic arterial phase using dual-energy MDCT. MATERIALS AND METHODS: An anthropomorphic liver phantom in three body sizes and iodine-containing inserts simulating low- and high-contrast hypervascular lesions was imaged with dual- and single-energy MDCT at various energy levels (80, 100, 120, and 140 kVp). Dual-energy MDCT was also performed in 48 patients with 114 hypervascular liver tumors; virtual monochromatic images were reconstructed at energy levels from 40 to 140 keV. The effect of body size and lesion iodine concentration on noise and tumor-to-liver contrast-to-noise ratio was compared among different datasets for phantoms and patients. RESULTS: The highest tumor-to-liver contrast-to-noise ratio was noted at 80 kVp for all phantom sizes. On virtual monochromatic images, the minimum noise was noted at 70 keV for small and medium phantoms and at 80 keV for the large phantom. Tumor-to-liver contrast-to-noise ratio was highest at 50 keV for small and medium phantoms and at 60 keV for the large phantom (p<0.0001). Compared with 80-kVp images, an optimal monochromatic energy level yielded a significantly higher (p<0.0001) tumor-to-liver contrast-to-noise ratio for high-contrast lesions in the large body size and for low-contrast lesions in all phantom sizes. In patients, the optimal monochromatic energy level for tumor-to-liver contrast-to-noise ratio increased proportionally along with body size (p<0.0001). CONCLUSION: Selection of the optimal monochromatic energy level for maximizing the conspicuity of hypervascular liver tumors is significantly affected by patient's body size.


Assuntos
Tamanho Corporal , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/fisiopatologia , Tomografia Computadorizada Multidetectores/métodos , Neovascularização Patológica/diagnóstico por imagem , Neovascularização Patológica/fisiopatologia , Intensificação de Imagem Radiográfica/métodos , Humanos , Neoplasias Hepáticas/complicações , Tomografia Computadorizada Multidetectores/instrumentação , Neovascularização Patológica/complicações , Imagens de Fantasmas , Doses de Radiação , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/instrumentação , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Razão Sinal-Ruído
13.
J Appl Clin Med Phys ; 13(3): 3724, 2012 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-22584168

RESUMO

Target localization using single photon emission computed tomography (SPECT) and planar imaging is being investigated for guiding radiation therapy delivery. Previous studies on SPECT-based localization have used computer-simulated or hybrid images with simulated tumors embedded in disease-free patient images where the tumor position is known and localization can be calculated directly. In the current study, localization was studied using scanner-acquired images. Five fillable spheres were placed in a whole body phantom. Sphere-to-background 99mTc radioactivity was 6:1. Ten independent SPECT scans were acquired with a Trionix Triad scanner using three detector trajectories: left lateral 180°, 360°, and right lateral 180°. Scan time was equivalent to 4.5 min. Images were reconstructed with and without attenuation correction. True target locations were estimated from 12 hr SPECT and CT images. From the 12 hr SPECT scan, 45 sets of orthogonal planar images were used to assess target localization; total acquisition time per set was equivalent to 4.5min. A numerical observer localized the center of the targets in the 4.5 min SPECT and planar images. SPECT-based localization errors were compared for the different detector trajectories. Across the four peripheral spheres, and using optimal iteration numbers and postreconstruction smoothing, means and standard deviations in localization errors were 0.90 ± 0.25 mm for proximal 180° trajectories, 1.31 ± 0.51 mm for 360° orbits, and 3.93 ± 1.48 mm for distal 180° trajectories. This rank order in localization performance is predicted by target attenuation and distance from the target to the collimator. For the targets with mean localization errors < 2 mm, attenuation correction reduced localization errors by 0.15 mm on average. The improvement from attenuation correction was 1.0 mm on average for the more poorly localized targets. Attenuation correction typically reduced localization errors, but for well-localized targets, the detector trajectory generally had a larger effect. Localization performance was found to be robust to iteration number and smoothing. Localization was generally worse using planar images as compared with proximal 180° and 360° SPECT scans. Using a proximal detector trajectory and attenuation correction, localization errors were within 2 mm for the three superficial targets, thus supporting the current role in biopsy and surgery, and demonstrating the potential for SPECT imaging inside radiation therapy treatment rooms.


Assuntos
Algoritmos , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Humanos , Aumento da Imagem/métodos , Imagens de Fantasmas , Radioterapia Guiada por Imagem
14.
Violence Against Women ; 27(14): 2664-2686, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-33529567

RESUMO

Half of today's domestic violence (DV) advocates are survivors of intimate partner violence (IPV) or other forms of abuse. Yet, little is known about the experiences of those who are both survivors and advocates, especially regarding organizational relationships, policies, and culture, and how these factors shape well-being. This grounded theory study of 12 survivor-advocates identified three dimensions of organizational support that contribute survivor-advocates' well-being: acknowledging their trauma-related needs, fostering belonging, and honoring strengths. In each case, these organizational factors contribute to well-being through the mechanism of validating their identities as survivors. Suggestions for organizations to better support survivor-advocates are discussed.


Assuntos
Violência Doméstica , Violência por Parceiro Íntimo , Teoria Fundamentada , Humanos , Organizações , Sobreviventes
15.
AJR Am J Roentgenol ; 195(2): 310-20, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20651185

RESUMO

OBJECTIVE: There is growing interest in using PET/CT for evaluating early response to therapy in cancer treatment. Although widely available and convenient to use, standardized uptake value (SUV) measurements can be influenced by a variety of biologic and technologic factors. Many of these factors can be addressed with close attention to detail and appropriate quality control. This article will review factors potentially affecting SUV measurements and provide recommendations on ways to minimize when using serial PET to assess early response to therapy. CONCLUSION: Scanner and reconstruction parameters can significantly affect SUV measurements. When using serial SUV measurements to assess early response to therapy, imaging should be performed on the same scanner using the same image acquisition and reconstruction protocols. In addition, attention to detail is required for accurate determination of the administered radiopharmaceutical dose.


Assuntos
Algoritmos , Fluordesoxiglucose F18/farmacocinética , Interpretação de Imagem Assistida por Computador/métodos , Neoplasias/diagnóstico por imagem , Neoplasias/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Humanos , Aumento da Imagem/métodos , Modelos Biológicos , Compostos Radiofarmacêuticos/farmacocinética , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
16.
Med Phys ; 47(4): 1633-1639, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32040862

RESUMO

PURPOSE: Phantoms are useful tools in diagnostic CT, but practical limitations reduce phantoms to being only a limited patient surrogate. Furthermore, a phantom with a single cross sectional area cannot be used to evaluate scanner performance in modern CT scanners that use dose reduction techniques such as automated tube current modulation (ATCM) and iterative reconstruction (IR) algorithms to adapt x-ray flux to patient size, reduce radiation dose, and achieve uniform image noise. A new multisized phantom (Mercury Phantom, MP) has been introduced, representing multiple diameters. This work aimed to ascertain if measurements from MP can predict radiation dose and image noise in clinical CT images to prospectively inform protocol design. METHODS: The adult MP design included four different physical diameters (18.5, 23.0, 30.0, and 37.0 cm) representing a range of patient sizes. The study included 1457 examinations performed on two scanner models from two vendors, and two clinical protocols (abdominopelvic with and chest without contrast). Attenuating diameter, radiation dose, and noise magnitude (average pixel standard deviation in uniform image) was automatically estimated in patients and in the MP using a previously validated algorithm. An exponential fit of CTDIvol and noise as a function of size was applied to patients and MP data. Lastly, the fit equations from the phantom data were used to fit the patient data. In each patient distribution fit, the normalized root mean square error (nRMSE) values were calculated in the residuals' plots as a metric to indicate how well the phantom data can predict dose and noise in clinical operations as a function of size. RESULTS: For dose across patient size distributions, the difference between nRMSE from patient fit and MP model data prediction ranged between 0.6% and 2.0% (mean 1.2%). For noise across patient size distributions, the nRMSE difference ranged between 0.1% and 4.7% (mean 1.4%). CONCLUSIONS: The Mercury Phantom provided a close prediction of radiation dose and image noise in clinical patient images. By assessing dose and image quality in a phantom with multiple sizes, protocol parameters can be designed and optimized per patient size in a highly constrained setup to predict clinical scanner and ATCM system performance.


Assuntos
Imagens de Fantasmas , Doses de Radiação , Razão Sinal-Ruído , Tomografia Computadorizada por Raios X/instrumentação , Humanos
17.
Science ; 367(6485): 1461-1464, 2020 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-32217723

RESUMO

The wave function of a Tonks-Girardeau (T-G) gas of strongly interacting bosons in one dimension maps onto the absolute value of the wave function of a noninteracting Fermi gas. Although this fermionization makes many aspects of the two gases identical, their equilibrium momentum distributions are quite different. We observed dynamical fermionization, where the momentum distribution of a T-G gas evolves from bosonic to fermionic after its axial confinement is removed. The asymptotic momentum distribution after expansion in one dimension is the distribution of rapidities, which are the conserved quantities associated with many-body integrable systems. Our measurements agree well with T-G gas theory. We also studied momentum evolution after the trap depth is suddenly changed to a new nonzero value, and we observed the theoretically predicted bosonic-fermionic oscillations.

18.
Med Phys ; 45(10): 4377-4391, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30053326

RESUMO

PURPOSE: The purpose of this study was to determine whether a proposed suite of objective image quality metrics for digital chest radiographs is useful for monitoring image quality in a clinical setting unique from the one where the metrics were developed. METHODS: Seventeen gridless AP chest radiographs from a GE Optima portable digital radiography (DR) unit ("sub-standard" images; Group 2) and 17 digital PA chest radiographs ("standard-of-care" images; Group 1) and 15 gridless (non-routine) PA chest radiographs (images with a gross technical error; Group 3) from a Discovery DR unit were chosen for analysis. Group 2 images were acquired with a lower kVp (100 vs 125) and shorter source-to-image distance (127 cm vs 183 cm) and were expected to have lower quality than Group 1 images. Group 3 images were expected to have degraded contrast vs Group 1 images. Images were anonymized and securely transferred to the Duke University Clinical Imaging Physics Group for analysis using software described and validated previously. Individual image quality was reported in terms of lung gray level, lung detail, lung noise, rib-lung contrast, rib sharpness, mediastinum detail, mediastinum noise, mediastinum alignment, subdiaphragm-lung contrast, and subdiaphragm area. Metrics were compared across groups. To improve precision of means and confidence intervals for routine exams, an additional 66 PA images were acquired, processed, and pooled with Group 1. Three observer studies were conducted to assess whether humans were able to identify images classified by the algorithm as abnormal. RESULTS: Metrics agreed with published Quality Consistency Ranges with three exceptions: higher lung gray level, lower rib-lung contrast, and lower subdiaphragm-lung contrast. Higher (stored) bit depth (14 vs 12) accounted for higher lung gray level values in our images. Values were most internally consistent for Group 1. The most sensitive metric for distinguishing between groups was mediastinum noise, followed closely by lung noise. The least sensitive metrics were mediastinum detail and rib-lung contrast. The algorithm was more sensitive than human observers at detecting suboptimal diagnostic quality images. CONCLUSIONS: The software appears promising for objectively and automatically identifying suboptimal images in a clinical imaging operation. The results can be used to establish local quality consistency ranges and action limits per facility preferences.


Assuntos
Tórax/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Automação , Humanos , Controle de Qualidade
19.
Am J Orthopsychiatry ; 86(3): 286-96, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27196389

RESUMO

Over the last 4 decades, domestic violence (DV) programs-both residential and nonresidential-have sprung up in communities across the country with the aim of helping survivors become safe. These programs place strong emphasis on the relationship between the advocate and survivor as critical to becoming safer and healing from the trauma of abuse. Yet little research has demonstrated the extent to which specific aspects of the advocate-survivor alliance are related to specific indicators of survivor well-being, nor shown what factors might mediate that relationship. This study explored in a sample of help-seeking survivors (N = 370) whether the strength of the alliance between survivors and their advocates is related to lower symptoms of depression and posttraumatic stress disorder (PTSD) and whether this association is mediated by survivors' sense of empowerment in the domain of safety. The structural equation model we tested also controlled for variables that might influence these relationships, including race/ethnicity, financial strain, and length of stay in the program. As expected, stronger alliance was associated with reduced symptoms of both depression and PTSD, through the mechanism of empowerment in the domain safety. These findings provide direction to programs seeking to establish a theory of change and point the way toward longitudinal research on the nature and function of the alliance as a potential contributor to healing. (PsycINFO Database Record


Assuntos
Violência Doméstica/psicologia , Saúde Mental/etnologia , Poder Psicológico , Sobreviventes/psicologia , Adulto , Estudos Transversais , Depressão/etnologia , Depressão/psicologia , Violência Doméstica/etnologia , Feminino , Humanos , Masculino , Apoio Social , Transtornos de Estresse Pós-Traumáticos/etnologia , Transtornos de Estresse Pós-Traumáticos/psicologia
20.
Am J Orthopsychiatry ; 85(6): 586-99, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26594925

RESUMO

Three out of 10 women and 1 out of 10 men in the United States experience violence at the hands of an intimate partner-often with devastating costs. In response, hundreds of residential and community-based organizations have sprung up to support survivors. Over the last decade, many of these organizations have joined other human service systems in adopting trauma-informed care (TIC), an approach to working with survivors that responds directly to the effects of trauma. Although there have been various efforts to describe TIC in domestic violence (DV) programs, there is a need to further synthesize this discourse on trauma-informed approaches to better understand specific applications and practices for DV programs. This study aimed to address this gap. The authors of this study systematically identified key documents that describe trauma-informed approaches in DV services and then conducted a qualitative content analysis to identify core themes. Results yielded 6 principles (Establishing emotional safety, Restoring choice and control, Facilitating connection, Supporting coping, Responding to identity and context, and Building strengths), each of which comprised a set of concrete practices. Despite the common themes articulated across descriptions of DV-specific trauma-informed practices (TIP), we also found critical differences, with some publications focusing narrowly on individual healing and others emphasizing the broader community and social contexts of violence and oppression. Implications for future research and evaluation are discussed. (PsycINFO Database Record


Assuntos
Violência Doméstica , Serviços de Saúde Mental , Trauma Psicológico/reabilitação , Humanos
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