Search results for "Photon"
showing 10 items of 3171 documents
The population-based prevalence of osteoporotic vertebral fracture and densitometric osteoporosis in postmenopausal women over 50 in Valencia, Spain …
2010
Purpose: To estimate the prevalence of vertebral fracture and densitometric osteoporosis in postmenopausal women over the age of 50 in Valencia, Spain. Methods: This cross-sectional study was conducted in 2006-2007. An age-stratified population-based random sample of 824 postmenopausal women over the age of 50 answered a questionnaire and received a densitometric examination of the lumbar spine and hip with dual-energy X-ray absorptiometry and a lateral X-ray of the thoracic spine and lumbar regions. Osteoporosis was defined as a T-score less than or equal to -2.5 compared to a population of young women, and the presence of vertebral fractures was classified according to Genant's semiquanti…
Radiation transmission data for radionuclides and materials relevant to brachytherapy facility shielding
2008
To address the limited availability of radiation shielding data for brachytherapy as well as some disparity in existing data, Monte Carlo simulation was used to generate radiation transmission data for 60Co, 137CS, 198Au, 192Ir 169Yb, 170Tm, 131Cs, 125I, and 103pd photons through concrete, stainless steel, lead, as well as lead glass and baryte concrete. Results accounting for the oblique incidence of radiation to the barrier, spectral variation with barrier thickness, and broad beam conditions in a realistic geometry are compared to corresponding data in the literature in terms of the half value layer (HVL) and tenth value layer (TVL) indices. It is also shown that radiation shielding calc…
Effects of calcium, dairy product, and vitamin D supplementation on bone mass accrual and body composition in 10-12-y-old girls: a 2-y randomized tri…
2005
Little is known about the relative effectiveness of calcium supplementation from food or pills with or without vitamin D supplementation for bone mass accrual during the rapid growth period.The purpose was to examine the effects of both food-based and pill supplements of calcium and vitamin D on bone mass and body composition in girls aged 10-12 y.This placebo-controlled intervention trial randomly assigned 195 healthy girls at Tanner stage I-II, aged 10-12 y, with dietary calcium intakes900 mg/d to 1 of 4 groups: calcium (1000 mg) + vitamin D3 (200 IU), calcium (1000 mg), cheese (1000 mg calcium), and placebo. Primary outcomes were bone indexes of the hip, spine, and whole body by dual-ene…
Optical analysis to predict outcomes after implantation of a double intraocular lens magnification device.
2007
Purpose To analyze the effect of different optical parameters of the eye on the outcomes of implantation of a double intraocular lens (IOL) magnification device in patients with low vision. Setting Fundacion Oftalmologica del Mediterraneo, Valencia, Spain. Methods The eye's refraction and magnification before and after surgery were evaluated using a theoretical eye model based on paraxial optics approximation. Four parameters on which refraction and magnification are dependent were evaluated: anterior chamber depth (ACD), axial length (AL), mean keratometry (Km), and the distance between the 2 implanted IOLs. The 4 variables were analyzed separately in the first stage. Next, different combi…
New Trends in Detectors for Medical Imaging
2010
The improvement of medical imaging instrumentation is based both on the enhancement of the performance of the detectors employed in their construction and on the development of novel techniques and methods that allow full exploitation of the advantages of the new instrumentation.
Effect of 2 years of endurance and high-impact training on preventing osteoporosis in postmenopausal women: randomized clinical trial.
2018
The aim of the study was to analyze the effects of endurance and high-impact training oriented toward preventing osteoporosis in postmenopausal women with calcium and vitamin D supplementation.This study was a randomized clinical trial. Thirty-six postmenopausal women were randomized to the control and experimental groups. Thirty-four women completed the 2-year interventions. The control group training involved walking at an intense pace. The experimental group conducted high-impact training specifically oriented to prevent osteoporosis. Dual-energy x-ray absorptiometry was used to estimate the T-scores of the lumbar spine and femoral neck.The fast-walking group showed constant T-scores in …
D2-receptor imaging with [123I]IBZM and Single Photon Emission Tomography in psychiatry: a survey of current status
1995
D2-dopamine receptors can be visualized in the human brain in vivo by Single Photon Emission Tomography (SPECT) and the radiolabeled benzamide [123I]IBZM. The present paper reviews the current status of this type of functional brain imaging with respect to basic methodological aspects, data analysis and quantification. The results from published clinical studies in different psychiatric patient populations and normal controls with [123I]IBZM are reviewed. [123I]IBZM-SPECT is a powerful tool for the investigation of D2-dopamine receptor status in psychiatric disorders, different types of drug treatment as well as therapeutic and side effects of pharmacologic agents. However, there still is a…
Sentinel Node Identification in Melanoma: Current Clinical Impact, New Emerging SPECT Radiotracers and Technological Advancements. An Update of the L…
2020
Background: Melanoma is the most lethal skin cancer with a mortality rate of 262 cases per 100.000 cases. The sentinel lymph node (SLN) is the first lymph node draining the tumor. SLN biopsy is a widely accepted procedure in the clinical setting since it provides important prognostic information, which helps patient management, and avoids the side effects of complete lymph node dissection. The rationale of identifying and removing the SLN relies on the low probability of subsequent metastatic nodes in case of a negative histological exam performed in the SLN. Discussion: Recently, new analytical approaches, based on the evaluation of scintigraphic images are also exploring the possibility …
Effect of CYP1A1 Gene Polymorphisms on Estrogen Metabolism and Bone Density
2004
UNLABELLED: In this study, we evaluated the effect of polymorphisms of the CYP1A1 gene, linked to hormone-related cancers, on estrogen metabolism and BMD. We found that variants carrying the A allele (CA and AA) for the C4887A polymorphism have a significantly higher degree of estrogen catabolism and lower femoral BMD. INTRODUCTION: Polymorphisms of the CYP1A1 gene, one of the key enzymes that metabolize estrogen, have been linked with hormone-related cancers. We investigated the impact of these polymorphisms on estrogen metabolism and BMD, which is another hormone-dependent health issue. MATERIALS AND METHODS: One hundred seventy postmenopausal women (mean age, 63.5 +/- 0.6 years) particip…
GEC-ESTRO ACROP recommendations on calibration and traceability of LE-LDR photon-emitting brachytherapy sources at the hospital level
2019
Prostate brachytherapy treatment using permanent implantation of low-energy (LE) low-dose rate (LDR) sources is successfully and widely applied in Europe. In addition, seeds are used in other tumour sites, such as ophthalmic tumours, implanted temporarily. The calibration issues for LE-LDR photon emitting sources are specific and different from other sources used in brachytherapy. In this report, the BRAPHYQS (BRAchytherapy PHYsics Quality assurance System) working group of GEC-ESTRO, has developed the present recommendations to assure harmonized and high-quality seed calibration in European clinics. There are practical aspects for which a clarification/procedure is needed, including aspect…