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At least 181 records · Page 10Linked to original sources

PubMed1993

An evaluation of two methods of anatomical alignment of radiotherapy portal images.

PURPOSE: Two techniques have been developed at our institution to allow anatomical registration of digitized portal images to a simulation film. Accuracy of the portal image alignment methods is tested and single intrauser and multiple interuser variation is examined using each technique. METHODS AND MATERIALS: Method one requires the identification of anatomical fiducial points on a simulation image and its corresponding portal image. The parameters required to align the corresponding points are calculated by a least squares fit algorithm. Method two uses an anatomical template generated from the simulation image and superimposing it upon a portal image. The template is then adjusted by a computer mouse to obtain the best subjective anatomical fit on the portal image. Megavoltage portal images of a skull phantom with various known shifts and eight clinical image files were aligned by each method. Each data set was aligned several times by both a single user and multiple users. RESULTS: Alignment of the anatomical phantom portal images demonstrates an accuracy of less than 0.8 +/- 0.9 mm and 0.7 +/- 1.0 degrees with either method. As out of plane rotation increased from 0 to 5 degrees, simulating out of plane malpositioning, alignment orthogonal to the plane of rotation worsened to 1.5 +/- 1.1 mm with the point method and 2.4 +/- 1.6 mm with the template method. Alignment parallel to the axis of the gantry rotation was insensitive to this change and remained constant as did the rotational alignment parameters. For the clinical image files the magnitude of variation for a single user is typically less than +/- 1 mm or +/- 1 degree. The magnitude of variation of alignment increased when multiple users aligned the same image files. The variation was dependent upon anatomical site and to a lesser degree the method of alignment used. The root mean square deviation of translational shifts range from +/- 0.68 mm when using the template method in the pelvis to as high as +/- 2.94 mm with the template method to align abdominal portal images. In the thorax and pelvis translational alignments along the horizontal axis were more precise than along the vertical axis. Multiple user variability was in part due to poor image quality, user experience, non rigidity of the anatomical features, and the difficulty in locating an exact point on a continuous anatomical structure. CONCLUSION: In well controlled phantom studies both the fiducial point and template method provide similar and adequate results. The phantom studies show that alignment error and variance increase with distortion in anatomical features secondary to out of plane rotations. In clinical situations intrauser variation is small, however, multiple interuser variation is larger. The magnitude of variation is dependent upon the anatomical site aligned.

Computer Simulation↗

PubMed1995

Early-onset drug use and risk of later drug problems.

Prior research has suggested that among illicit drug users there is an increased risk of drug abuse or dependence problems associated with earlier onset of illicit drug taking. This study examined whether the observed association might be understood best as the result of a process by which earlier onset users accumulate more time during which they can develop a drug problem (that is, more time since first illicit drug taking). Survival data analysis was employed to investigate this issue, with self-report data from 1525 illicit drug using individuals, all of whom were 18-24-year-old participants in the multi-site collaborative Epidemiologic Catchment Area Program. In the first year after initial illicit drug use, there was no appreciable variation in the estimated risk of developing a drug problem. However, with passage of some 5-7 years after initial use, the estimated risk of developing drug problems became clearly greater for youths whose drug taking had started during the pre-adolescent and very early adolescent years. The previously reported relationship between early-onset drug use and subsequent drug problems was not, therefore, an artifact of time. It is possible that duration of drug use should be considered as one 'mechanism' by which early-onset drug users experience greater risk of drug problems, but there also are other interpretations to be investigated in future research.

Adolescent↗

PubMed2005

Assistive devices for balance and mobility: benefits, demands, and adverse consequences.

OBJECTIVES: To provide information on the advantages and possible disadvantages of using canes and walkers. DATA SOURCES: English-language articles were identified by searching MEDLINE and PubMed (1966-May 2003) for key words cane or walker , excluding articles unrelated to mobility aids. Bibliographies were reviewed and ISI Web of Science citation searches were run to identify additional references. Over 1000 articles were selected for further evaluation. STUDY SELECTION: We extracted all studies of single-tip canes or pickup walkers addressing: (1) functional, biomechanic, or neuromotor benefits; (2) biomechanic, attentional, neuromotor, metabolic, or physiologic demands; and (3) falls, injuries, or other problems. We included approximately 10% of the articles originally identified. DATA EXTRACTION: The methodology of each selected article, and findings relevant to the benefits, demands, or adverse effects of cane or walker use were summarized. DATA SYNTHESIS: Findings were synthesized by considering their relation to basic biomechanic principles. Some biomechanic findings appear to support the clinical view that canes and walkers can improve balance and mobility for older adults and people with other clinical conditions. However, a large proportion of users experience difficulties, and the use of such devices is associated with increased risk of falling. A small number of studies have characterized some of the specific demands and problems associated with using mobility aids. CONCLUSIONS: Clinical and biomechanic evaluations of canes and walkers confirm that these devices can improve balance and mobility. However, they can also interfere with ones ability to maintain balance in certain situations, and the strength and metabolic demands can be excessive. More research is needed to identify and solve specific problems. Such research may lead to improved designs and guidelines for safer use of canes and walkers.

Adolescent↗

PubMed2025

Outcomes and effectiveness of decision aids for families affected by hereditary cancer syndromes: A scoping review.

PURPOSE: In the past 15 years, numerous decision aids (DAs) have been developed to assist families affected by hereditary cancer syndromes in decision-making for managing inheritance and cancer risk. We identified the range and characteristics of DAs, focusing on their development stage according to guideline recommendations, their outcomes, and effectiveness. METHODS: A comprehensive search was conducted in MEDLINE, EMBASE, Cochrane, CINAHL, and PsycINFO, along with manual searches. Eligible articles reported DAs for supporting families affected by hereditary cancer syndromes, published in English from inception to July 2024. Quality was assessed using the Mixed-Methods Appraisal Tool. RESULTS: From 15,066 records, 32 studies with a moderate risk of bias, reporting 23 unique DAs, were identified. Most DAs targeted women (69.6%) with hereditary breast and ovarian cancer syndrome (73.9%) in North America and Europe (81.3%), primarily supporting decisions on cancer risk-reduction strategies (56.5%) and genetic testing/counseling (47.8%). Only 4 DAs were consistent with guideline-recommended development process, including prototype development, alpha- and beta-testing. Development and alpha-testing outcomes included user experience, understandability, and psychological impact. Beta-testing evaluated decision-making capacity, quality of the decision-making process, psychological impact, and impact on decisions. DAs consistently improved decision-making capacity and quality of the decision-making process but showed variable effects on psychological outcomes and actual decision in risk management. CONCLUSION: DAs are underdeveloped for genetic, racial, or gender minorities, according to guideline-recommended development process. Future research should develop DAs for broader populations and clarify their effectiveness, particularly regarding psychological outcomes.

Humans↗

PubMed2006

District nursing staff and depression: a psychometric evaluation of Depression Attitude Questionnaire findings.

BACKGROUND: Mental health problems such as depression are common in primary care settings and patients with chronic medical problems are at an increased risk. This co-morbidity suggests that district nursing services are particularly likely to encounter psychological problems in their patients. Mental health problems are poorly recognised and inadequately treated in primary care. In part this may be due to stigmatising views of mental illness, which negatively influence help-seeking and user experiences. Likewise providers' attitudes are likely to play a significant part in the management of such problems. OBJECTIVES: The aims of this study were extend knowledge of district nursing staff attitudes to depression and explore the psychometric properties of a depression attitude measure used with this staff group. DESIGN AND SETTINGS: The Depression Attitude Questionnaire (DAQ) was used within a postal questionnaire survey of district nursing services in three areas, Jersey (Channel Islands), Lewisham, and Hertfordshire. PARTICIPANTS: All staff (community nurses, district nurses and home care staff) were contacted; 217 (66%) staff responded to the survey, and 189 (57%) completed the DAQ. RESULTS: Three factors were derived from the DAQ accounting for 47% of the variance. The factor solution appeared stable and provided meaningful dimensions, however the internal consistency of the measure and of its derived subscales was low (Cronbach's alpha between 0.59 and 0.64). The factors were labelled pessimism about depression and its treatment, tendency to defer to specialists, and professional ease in working with depressed patients. Staff responses revealed generally optimistic views concerning depression treatment, strongly rejecting deterministic attitudes to this condition. CONCLUSIONS: The DAQ has been widely employed to measure and compare attitudes of staff from various disciplines and specialisms. The current evaluation has provided a more detailed examination of its psychometric properties than previously available, but low internal consistency levels indicate further examination of this area is warranted.

Analysis of Variance↗

PubMed2004

Tissue-selective effects of tibolone on the breast.

Hormone treatment with an estrogen plus a progestagen (EPT) increases the risk of breast cancer. Both hormone activities are also induced by tibolone. In order to assess the breast safety of tibolone, it was evaluated in several pre-clinical models. The effects were inconclusive in breast cancer cell lines but, in various in vivo models, it did not stimulate the breast. In the 17,12-dimethylbenz(a)anthracene (DMBA) model, tibolone clearly inhibited the growth of breast tumors and, when given prophylactally, far less tumors developed. Ovariectomized monkeys showed no increase in the expression of the proliferation marker Ki67. The effects of tibolone and its metabolites on the steroid metabolizing enzymes in breast tissues were investigated in order to unravel its mode of action in the breast. Tibolone and its metabolites did not inhibit aromatase, but sulfatase was profoundly inhibited. The sulfated 3alpha-OH tibolone metabolite even showed irreversible inhibition of sulfatase. In addition, 17ss-hydroxysteroid dehydrogenase activities were slightly inhibited and sulfotransferase activity was stimulated at low concentrations. The consequence of these effects is that, for both endogenous estrogens and estrogenic-metabolites of tibolone, the equilibrium is preferential for the sulfated forms. The intracellular hormonal milieu tibolone and its metabolites also influence cellular homeostasis. It inhibits cell proliferation of normal breast epithelial cells and stimulates apoptosis. In this respect, tibolone behaves differently from estrogens. Clinical studies have shown that tibolone users experience less breast tenderness and do not show an increase in mammographic density as found with continuous combined EPT. The data concerning tibolone and breast cancer risk are inconclusive and require further investigation.

Bone and Bones↗

PubMed1997

Three-dimensional ultrasound device for rapid determination of bladder volume.

OBJECTIVES: We sought to assess the accuracy, reliability, and clinical utility of the noninvasive determination of bladder volume using an automated, compact three-dimensional (3-D) ultrasound device. METHODS: We prospectively tested 249 adult outpatients for accuracy (n = 182), by comparing scan versus catheter volumes, or reliability (n = 67), by comparing the scan readings of two independent observers. Two models of the bladder scan device were tested (BVI-2500, 1994 and 1995 models). RESULTS: Scan and catheter volumes were correlated (y = 1.02x + 12.6, R2 = 0.90, P < 0.001) across a range of zero to 1015 cc, regardless of which machine model was used. Scan volume underestimated catheter volume by an average of 10 cc in men and 20 cc in women. If a scan-predicted volume of 100 cc or greater were used as a cutpoint for clinical importance, the device exhibited a sensitivity of 97%, a specificity of 91%, and an overall accuracy of 94%. These results were not affected by age, gender, height, weight, diagnosis, uterine presence/prostate size, or user experience. The two observers, one a graduate physician and the other a college student, achieved essentially the same volume determinations (y = 0.96x + 0.13, R2 = 0.90, P < 0.001). CONCLUSIONS: Volume determinations obtained with the bladder scan device are accurate and reliable in adult outpatients. A special technician is not required. These results may be attributable to use of automated planimetry and 3-D volumetry, rather than a fixed geometric formula, to custom measure each bladder shape.

Adult↗

PubMed1984

The value of the Terry keratometer in predicting postoperative astigmatism.

The Terry keratometer was used immediately before and immediately after cataract surgery. The results were compared with keratometry readings taken before surgery and readings taken on the morning of the first postoperative day. The mean preoperative cylinder in 27 eyes was 1/2 diopter less than that measured prior to the start of surgery. Preoperative readings and readings obtained prior to the start of surgery differed by more than 1 diopter in 37% of eyes. The keratometer readings obtained at the end of the surgery in 63 eyes were flatter than those obtained on the first postoperative day. Forty-four percent of the intraoperative cylinder readings differed from postoperative readings by more than 2 diopters. The factors which can produce errors with the use of this instrument include changes in intraocular pressure, the effect of the lid speculum, rectus suture tension, the alignment of the eye with respect to the keratometer , and user experience.

Aged↗

PubMed2002

To what extent do oral contraceptives influence mood and affect?

BACKGROUND: Studies examining the effects of oral contraceptives (OCs) on mood, affect, and affect variability are reviewed. METHODS: MEDLINE and PsycLIT data bases were examined to identify studies that compared OC users with nonusers using daily ratings of mood, affect, or affect variability. RESULTS: Compared to non-users, OC users experience less variability in affect across the entire menstrual cycle, and less negative affect during menstruation (i.e. withdrawal bleeding). In women with OC-related negative mood and affect change, potential mediators of the relation between OCs and mood or affect were identified: a history of depression, psychiatric symptoms, dysmenorrhea, and premenstrual mood symptoms prior to OC use; a history of pregnancy-related mood symptoms; a family history of OC-related mood complaints; being in the postpartum period; and age. Furthermore, a lower ratio of progesterone to estrogen is associated with more negative mood change in women with a history of premenstrual emotional symptoms, higher progesterone to estrogen ratios are associated with increased negative mood effects in women without such a history, and monophasic OCs have a greater stabilizing effect on mood than triphasic OCs. LIMITATIONS: The 'survivor effect', psychological factors, and indirect pharmacological effects (e.g. weight gain) have not yet been systematically investigated. Furthermore, most studies have examined only negative mood or affect, as opposed to both positive and negative affect and affect variability; and few affect studies have assessed potential mediators of OC-related affect change. CONCLUSIONS: While the only consistent OC-related mood effects experienced by most women are beneficial, a subgroup of women do experience negative mood change. Future research must focus on expounding the individual difference and OC-related risk factors for negative mood change.

Adult↗

PubMed2002

Implementation and utility of a daily ultrasound-based localization system with intensity-modulated radiotherapy for prostate cancer.

PURPOSE: To evaluate the clinical feasibility of daily computer-assisted transabdominal ultrasonography for target position verification in the setting of intensity-modulated radiotherapy (IMRT) for prostate cancer. METHODS AND MATERIALS: Twenty-three patients with clinically localized prostate cancer were treated using a sequential tomotherapy IMRT technique (Peacock) and daily computer-assisted transabdominal ultrasonography (BAT) for target localization. Patients were instructed to maintain a full bladder and were placed in the supine position using triangulation tattoos and a leg immobilizer to minimize pelvic rotation. The BAT ultrasound system is docked to the treatment collimator and electronically imports the CT simulation target contours and isocenter. The system is able to use the machine isocenter as a reference point to overlay the corresponding CT contours onto the ultrasound images captured in the transverse and sagittal planes. A touch screen menu is used to maneuver the CT contours in three dimensions such that they match the ultrasound images. The system then displays the three-dimensional couch shifts required to produce field alignment. Data were prospectively collected to measure the frequency by which useful ultrasound images were obtained, the amount of time required for localization/setup, and the direction/magnitude of the positional adjustments. RESULTS: Of the 23 patients, the BAT ultrasound system produced images of sufficient quality to perform the overlay of the CT contours in 19 patients such that positional verification could be reliably performed. Poor image quality was associated with patient inability to maintain a full bladder, large body habitus, or other anatomic constraints. Of the 19 assessable patients, a total of 185 treatment alignments were performed (mean 8.8/patient). For all cases, the average time required for the daily ultrasound imaging and positional adjustments was 11.9 min. After the initial 5 cases, the user experience skills improved such that the time required for image verification/positional adjustments decreased to a mean of 5.6 min. The average right-left, AP, and cranial-caudal adjustment was 2.6 +/- 2.1 mm, 4.7 +/- 2.7 mm, and 4.2 +/- 2.8 mm, respectively. Positional adjustments >10 mm were infrequent and related primarily to misidentification of the target structures on the ultrasound image, patient movement, or improper registration of the triangulation tattoos. CONCLUSION: Daily computer-assisted BAT ultrasound positional verification of the prostate can be successfully performed through the acquisition of high-quality images in most patients with only a modest increase in treatment setup time. Positional data obtained with this system resulted in clinically meaningful adjustments in daily setup for sequential IMRT that would not be otherwise apparent from other verification modalities.

Algorithms↗

PubMed1997

Hormone replacement therapy and risk for breast cancer.

Because breast cancer will develop in one of every nine American women, even a small increase in risk associated with a widespread exposure is of substantial public health concern. Although most studies have not found ever use of estrogens to be a risk factor for breast cancer, it is not yet resolved whether current or long-term users experience some increase in risk. Given the fact that the indications for menopausal estrogen use have changed substantially over time, from short-term use for the relief of menopausal symptoms to long-term use for lifetime reduction of conditions such as cardiovascular disease and osteoporosis, it is imperative that the effects of long-term estrogen replacement on the risk for breast cancer be resolved. These studies are not without associated methodologic difficulties, with the ultimate interpretation of the association possibly dependent on the results of controlled clinical trials. Although such investigations are currently underway, the results will not be available for many years. To address more immediate concerns, continued emphasis should be placed on well-designed case-control and cohort studies. For the results to be reliable, attention must be directed to the effects of selection, recall and surveillance biases, confounding factors, detailed exposure relationships, subgroup variations, and disease associations. In addition, given the increasing trend for estrogens to be prescribed in combination with progestogens, the effects on breast tissue of this combined therapy merit immediate attention.

Breast Neoplasms↗

PubMedDate not supplied

Repetitive strain injury in computer keyboard users: pathomechanics and treatment principles in individual and group intervention.

Computer users experience high rates of injury and disability, broadly termed repetitive strain injury (RSI). With more than 60 million Americans using computers in offices and homes, the potential magnitude of the RSI problem indicates a need for increased attention to prevention and treatment. The purpose of this article is to: 1) present a conceptual model of RSI as a kinetic-chain, multifactorial disorder; 2) outline the salient features of the clinical evaluation of the RSI patient; 3) describe the role of postural deviation in the pathogenesis of RSI; 4) present the principles of individual manual therapy; and 5) discuss the rationale, admission criteria, educational principles, and outcome of a multidisciplinary group intervention.

Biomechanical Phenomena↗

PubMed2006

Stochastic approach to data analysis in fluorescence correlation spectroscopy.

Fluorescence correlation spectroscopy (FCS) has emerged as a powerful technique for measuring low concentrations of fluorescent molecules and their diffusion constants. In FCS, the experimental data is conventionally fit using standard local search techniques, for example, the Marquardt-Levenberg (ML) algorithm. A prerequisite for these categories of algorithms is the sound knowledge of the behavior of fit parameters and in most cases good initial guesses for accurate fitting, otherwise leading to fitting artifacts. For known fit models and with user experience about the behavior of fit parameters, these local search algorithms work extremely well. However, for heterogeneous systems or where automated data analysis is a prerequisite, there is a need to apply a procedure, which treats FCS data fitting as a black box and generates reliable fit parameters with accuracy for the chosen model in hand. We present a computational approach to analyze FCS data by means of a stochastic algorithm for global search called PGSL, an acronym for Probabilistic Global Search Lausanne. This algorithm does not require any initial guesses and does the fitting in terms of searching for solutions by global sampling. It is flexible as well as computationally faster at the same time for multiparameter evaluations. We present the performance study of PGSL for two-component with triplet fits. The statistical study and the goodness of fit criterion for PGSL are also presented. The robustness of PGSL on noisy experimental data for parameter estimation is also verified. We further extend the scope of PGSL by a hybrid analysis wherein the output of PGSL is fed as initial guesses to ML. Reliability studies show that PGSL and the hybrid combination of both perform better than ML for various thresholds of the mean-squared error (MSE).

Computer Simulation↗

PubMed2000

Exploring the effects of icon characteristics on user performance: the role of icon concreteness, complexity, and distinctiveness.

Because icons, signs, and symbols are now widely used to communicate information, it is essential for system designers to know what makes them easy to use and interpret. The authors report a series of studies that examine characteristics considered central to icon usability. After quantifying the properties of icon concreteness, complexity, and discriminability, the authors assessed each property's effects on user performance when user experience, task demands, and presentation context were systematically varied. Findings indicated that the effects of icon concreteness were primarily associated with the initial grasp of meaning, whereas complexity effects were found to persist longer and to be associated with search efficacy. The effects of icon distinctiveness were complex, but distinctiveness was enhanced by using both semantic and visual contrasts. The implications of these findings for interface design are discussed.

Adult↗

PubMed1982

Overamplification: a well-documented case report.

A well-documented case report is presented in which the use of a high-output hearing aid over a 10-year period resulted in significant threshold shifts in the aided as compared to the unaided ear. At no time did the user experience loudness discomfort and she consistently wanted more gain from the hearing aid, indicating that there is no relationship between loudness discomfort levels and the sound pressure levels at which damage to the auditory system occurs. Difficulties in detecting the cause of the threshold shifts and recommendations for case management are discussed.

Adult↗

PubMed1996

Health status at entry to methadone maintenance treatment using the SF-36 health survey questionnaire.

This study used the SF-36 general health questionnaire to measure the health status of heroin users at entry to a public methadone maintenance programme. Their results were compared to those from the general population and from three clinical groups: patients with minor medical, major medical and psychiatric problems. One hundred consecutive clients were interviewed in the first week on the programme using the SF-36 health questionnaire. Data were also gathered on their drug use, use of medical services and HIV risk behaviour. The results showed that heroin users at entry to the methadone maintenance programme had significantly worse physical and psychological health than the general population. Their scores were most similar to the psychiatrically depressed patients, although they had worse physical health than this comparison group. The greater the amount of heroin used by clients before entering the programme, the more pain they reported. Alcohol and marijuana use were associated with better social and physical health. The relationship between general health status and amount or frequency of drug use is not a clear one. Heroin users experience severe emotional and physical problems at the time of entering methadone maintenance treatment.

Adolescent↗

PubMed1999

Discourses on empowerment.

The discourse community of British psychiatric and mental health nursing is a contested realm. The 'Big Stories' of policy and planning of services are clearly articulated in disputes in journals, but the 'Little Stories' of nurses' work and patients' or users' experiences may be ignored or under-valued. This paper illustrates how the Big Story of a central theme in current policy--empowerment--is articulated in the realm of research funding and design, and how it is articulated by practitioners. The paper focuses attention on the responsibilities faced by researchers, in relating the Little Stories of practice and the Big Story of policy. It reports early and tentative findings from a study of community psychiatric nurses' empowerment of people with enduring mental disorders. The paper suggests ways in which strategies for analysis of qualitative data from interviews with CPNs may be informed by ideas drawn from the field of discourse analysis; reflexively examining how researchers' discourses relate to those of policy makers and mental health nursing practitioners. This paper is based on a presentation at the Network for Psychiatric Nursing Research Conference, Napier University, Edinburgh, 17 September 1997.

Attitude of Health Personnel↗

PubMed2006

Ultrasound-guided breast interventions: accuracy of biopsy techniques and applications in patient management.

Ultrasound (US) provides a versatile approach for guiding biopsies and other breast interventions. The wide availability, real-time capability, technical improvements, and increasing user experience have greatly expanded the role of US-guided interventions in the diagnosis and management of breast disease. This article reviews the accuracy of US-guided fine-needle aspiration biopsy, automated core biopsy, and vacuum-assisted biopsy. Some of the more specialized procedures that reflect the growing role of US-guided interventions in patient management will also be discussed.

Biopsy↗