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Results for “Dose reduction”

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At least 343 records · Page 19Linked to original sources
PubMed2001

[Spiral CT of the abdomen: weight-adjusted dose reduction].

AIM OF THE STUDY: The influence of weight-adjusted current application in spiral CT of the abdomen on noise was investigated in a clinical study. PATIENTS AND METHODS: In 77 routine abdominal CT investigations (120 kV, 8 mm, pitch 1.5) the patients were divided into three body-weight groups A (< 60 kg), B (60-80 kg), and C (> 80 kg). The tube current was randomized prospectively in low weight group A, either 125 mA or 150 mA, in middle and high weight groups B and C, 150, 175 or 200 mA, with a tube revolution time of one second. The noise was measured in liver, skeleton muscle, fat tissue, and bladder content for evaluation of image quality. RESULTS: The bodyweight groups differ significantly in noise, e.g., in the liver (150 mA): group A: 15.8 HU, group B: 18.9 HU, group C: 21.5 HU. The increase of tube current (150, 175, 200 mA) within a body weight group resulted in a minor decrease of noise (18.9 HU, 17.6 HU, 17.5 HU, respectively, in group B). There is a good correlation of noise with body weight, body mass index and body cross section, but not with body size. CONCLUSION: A body weight adjusted reduction of tube current is possible without an increase of noise.

Adipose Tissue↗
PubMed2004

Multi-detector row CT: effect of iodine dose reduction on hepatic and vascular enhancement.

PURPOSE: To evaluate the impact of different iodine concentrations of intravenous contrast agent on hepatic and vascular enhancement during arterial and porto-venous phase imaging using a 4-channel multi-detector row CT (MDCT). MATERIAL AND METHODS: One hundred consecutive patients referred for triphasic abdominal MDCT were randomly assigned into four groups receiving different iodine concentration (200, 250, 300 or 350 mg/ml). Non-contrast, arterial, and porto-venous phase 4-channel MDCT imaging was performed (VolumeZoom, Siemens, Germany). A fixed volume of 150 ml intravenous contrast agent at a rate of 3 ml/s was injected using an automatic bolus-tracking system (Care Bolus, Siemens, Erlangen). Hepatic and vascular enhancement values were measured over time and non-contrast values were subtracted in order to compute arterial and porto-venous mean hepatic (MHE) and mean aortic (MAE) enhancement for each group. Mean change of enhancement > 80 HU for the aorta and > 40 HU for the liver during porto-venous phase imaging was considered as sufficient enhancement. RESULTS: All groups achieved sufficient vascular enhancement during arterial phase imaging; MAE with 350 mg/ml (222 HU) and 300 mg/ml (213HU) was significantly better than with 250 mg (196HU) and 200 mg/ml (169 HU), whereas MHE showed no statistically significant difference between the groups (range 16 - 25 HU). Porto-venous MHE showed increased enhancement with larger concentrations, with significant differences among the groups. Only the higher concentration groups (350 mg/ml und 300 mg/ml) fulfilled in every individual the guidelines for sufficient porto-venous MHE. In the lower concentration groups, 8 patients with 200 mg/ml and 3 patients with 250 mg/ml showed enhancement values below the required minimum. CONCLUSION: A decrease in iodine contrast agent down to 200 mg/ml concentration is only tenable for propose of vascular aortic and hepatic arterial enhancement, whereas hepatic porto-venous phase imaging still requires concentrations at or above the level of 300 mg/ml.

Adult↗
PubMed2004

Insulin resistance after renal transplantation: the effect of steroid dose reduction and withdrawal.

Cardiovascular disease is a prevalent and serious complication after solid organ transplantation. Treatment with glucocorticoids is associated with increased risk for diabetes mellitus, insulin resistance, weight gain, hypercholesterolemia, and hypertension, all shown to be independent risk factors for cardiovascular disease. We sought to test the hypothesis that tapering of prednisolone (TAP) the first year after renal transplantation improves insulin sensitivity (IS), and to assess the effect of complete steroid withdrawal (SW) on IS in patients on a cyclosporine-based immunosuppressive regimen. All patients (n = 57) completed two consecutive hyperinsulinemic euglycemic glucose clamp procedures, a TAP group (n = 34) and a control group (n = 12) at 3 and 12 mo after transplantation, and a SW group (n = 11) before and 5 mo after SW. The IS index (ISI) was calculated as the glucose disposal rate divided by mean serum insulin the last 60 min of the clamp. In the TAP group, the mean (range) daily prednisolone was reduced from 16 (10 to 30) to 9 (5 to 12.5) mg accompanied by an average increased ISI of 24% (P = 0.008). In contrast, no significant change in ISI was observed in the control group (0%, P = 0.988). In the SW group, withdrawal of 5 mg prednisolone did not influence mean ISI significantly (-8%, P = 0.206). Lowering daily prednisolone toward 5 mg/d has beneficial effects on insulin action after renal transplantation, but withdrawal of 5 mg prednisolone may not influence IS significantly.

Body Weight↗
PubMedDate not supplied

Double-blind dose reduction study of vigabatrin in complex partial epilepsy.

Seventy-five epilepsy patients with at least two complex partial seizures/month were treated with gamma-vinyl GABA (GVG) 3 g/day for 3 months. Forty-one patients (54%) showed a reduction of greater than or equal to 50% in seizures. The median monthly seizure frequency decreased from 11.5 to 4 seizures/month. Twenty percent of patients had an improvement in general performance without a significant reduction in seizures. The responders entered the second phase of the study, in which 28 patients were randomly allocated to 3 g/day and 25 patients to 1.5 g/day GVG under double-blind conditions. The dosage of 3 g/day appeared to be clearly more effective than 1.5 g/day. However, even with 1.5 g/day GVG the seizure frequency was significantly reduced as compared to baseline. Drowsiness was the most commonly observed side effect, and it diminished with continued treatment. In three cases side effects led to the withdrawal of GVG therapy.

Adolescent↗
PubMedDate not supplied

Descriptive ethics and neuroleptic dose reduction.

TOPIC: Descriptive ethics and related concepts of beneficence, justice, and autonomy. PURPOSE: To provide a framework to aid in decision making when neuroleptic drugs are decreased in a vulnerable elderly population. SOURCE: A clinical situation is used to illustrate the ethical issues considered in neuroleptic drug reduction. CONCLUSION: While compassion permeates the ethical concerns of psychiatric mental health nurses, disciplined thought is also needed.

Aged↗
PubMedDate not supplied

Lead shielding thickness for dose reduction of 5 MeV electrons.

The relative percent intensity reduction by lead (Pb) of 5 MeV electrons produced by Siemens Mevatron 77/74 for 5 cm diameter, 10 X 10, 15 X 15, and 20 X 20 cm2 cones both with and without buildup is measured. The thickness of lead (Pb) required to attenuate the intensity of the primary electron beam to 95% and 98% depends upon the cone size and upon the depth in phantom at which transmission measurements are made.

Electrons↗