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Parallel and converging hole collimators are most frequently used in nuclear medicine. Less common is the use of rotating slat collimators for single photon emission computed tomography (SPECT). The higher photon collection efficiency, inherent to the geometry of rotating slat collimators, results in much lower noise in the data. However, plane integrals contain spatial information in only one direction, whereas line integrals provide two-dimensional information. It is not a trivial question whether the initial gain in efficiency will compensate for the lower information content in the plane integrals. Therefore, a comparison of the performance of parallel hole and rotating slat collimation is needed. This study compares SPECT with rotating slat and parallel hole collimation in combination with MLEM reconstruction with accurate system modeling and correction for scatter and attenuation. A contrast-to-noise study revealed an improvement of a factor 2-3 for hot lesions and more than a factor of 4 for cold lesion. Furthermore, a clinically relevant case of heart lesion detection is simulated for rotating slat and parallel hole collimators. In this case, rotating slat collimators outperform the traditional parallel hole collimators. We conclude that rotating slat collimators are a valuable alternative for parallel hole collimators. 相似文献
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Nathalie Roussel Jo Nijs Steven Truijen Liesbet Vervecken Sarah Mottram Gaëtane Stassijns 《European spine journal》2009,18(7):1066-1073
The objective of the study was to evaluate the breathing pattern in patients with chronic non-specific low back pain (LBP)
and in healthy subjects, both at rest and during motor control tests. Ten healthy subjects and ten patients with chronic LBP
participated at this case–control study. The breathing pattern was evaluated at rest (standing and supine position during
both relaxed breathing and deep breathing) and while performing clinical motor control tests, i.e. bent knee fall out and
active straight leg raise. A blinded observer analyzed the breathing pattern of the participants using visual inspection and
manual palpation. Costo-diaphragmatic breathing was considered as optimal breathing pattern. Subjects filled in visual analog
scales for the assessment of pain intensity during the tests. At rest, no significant differences were found between the breathing
pattern of patients and healthy subjects (P > 0.05). In contrast, significantly more altered breathing patterns were observed in chronic LBP-patients during motor control
tests (P = 0.01). Changes in breathing pattern during motor control tests were not related to pain severity (P > 0.01), but were related to motor control dysfunction (P = 0.01). 相似文献
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The aim of this study was to investigate which homogeneous groups, according to teacher reports of attention-deficit/hyperactivity (ADH) Problems on the Teacher's Report Form (TRF), can be identified in a referred sample (n = 4,422; age = 6-18 years; mean age = 9.9 years; 66% boys, 34% girls). Latent class analysis (LCA) was conducted on ADH Problems. In addition, co-morbidity levels in the different ADH Problems groups were compared. LCA yielded three different groups of children and adolescents with both Inattention and hyperactivity-impulsivity, and one group with high scores on Inattention but low scores on hyperactivity-impulsivity. A group of patients with predominantly hyperactivity and impulsivity was not found. Individuals in groups with higher levels of ADH Problems had significantly higher levels of oppositional defiant (OD) and conduct problems, and, although to a lesser extent, significantly higher levels of affective and anxiety problems than individuals in groups with lower levels of ADH Problems. It may not be useful to discern the hyperactive-impulsive type of ADHD. 相似文献
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Cancer-related fatigue (CRF) is a common symptom in patients treated for cancer. For patients receiving chemotherapy, the prevalence is 75% to 90%; in those receiving radiation, 65%. The management of CRF is difficult because its nature is not yet fully explained and it has a variety of causes. The purpose of the review is to identify interventions that can be used by nurses successfully to reduce fatigue during cancer treatment. A search of the medical (PubMed) and nursing (CINAHL) literature (1995 to February 2005) produced 18 studies. In two-thirds of the studies, the populations were breast cancer patients. Half of the studies had a sample size of less then 30 patients. The studies included dealt with sleep promotion (1), instruction and education (5), exercise (10), and distraction and relaxation (2). Significant effects were found in studies promoting exercise. For interventions on sleep promotion and on education and counseling, a positive result was found, but this was not significant. For distraction and relaxation, only an effect until a few hours after the intervention was found. Given the multidimensional nature of CRF, a combination of interventions is most likely to be effective. Thus far, such an approach by nurses during cancer treatment has not been tested. 相似文献