A coded aperture microscope for X-ray fluorescence full-field imaging.

The design and construction of an instrument for full-field imaging of the X-ray fluorescence emitted by a fully illuminated sample are presented. The aim is to produce an X-ray microscope with a few micrometers spatial resolution, which does not need to scan the sample. Since the fluorescence from a spatially inhomogeneous sample may contain many fluorescence lines, the optic which will provide the magnification of the emissions must be achromatic, i.e. its optical properties must be energy-independent. The only optics which fulfill this requirement in the X-ray regime are mirrors and pinholes. The throughput of a simple pinhole is very low, so the concept of coded apertures is an attractive extension which improves the throughput by having many pinholes, and retains the achromatic property. Modified uniformly redundant arrays (MURAs) with 10 µm openings and 50% open area have been fabricated using gold in a lithographic technique, fabricated on a 1 µm-thick silicon nitride membrane. The gold is 25 µm thick, offering good contrast up to 20 keV. The silicon nitride is transparent down into the soft X-ray region. MURAs with various orders, from 19 up to 73, as well as their respective negative (a mask where open and closed positions are inversed compared with the original mask), have been made. Having both signs of mask will reduce near-field artifacts and make it possible to correct for any lack of contrast.

Menarcheal age of mothers and daughters: Tehran lipid and glucose study.

There is some evidence for a decreasing age of menarche in many populations. This study examined the secular trend of age at menarche among Iranian women. Age at menarche based on recall information was recorded for 770 pairs of mother and daughters. Between 1930 and 1990 mean menarcheal age of this cohort of women decreased from 13.88 to 12.98 years (-0.15 years per decade) and mean height of the cohort increased from 152.33 to 158.43 cm (+0.99 cm per decade). There was a significant correlation between menarcheal age of mothers and their daughters (r = 0.27). Year of birth, mother's menarcheal age and daughter's height were significant predictors of daughter's menarcheal age.

Menarcheal age of mothers and daughters: Tehran Lipid and Glucose Study

There is some evidence for a decreasing age of menarche in many populations. This study examined the secular trend of age at menarche among Iranian women. Age at menarche based on recall information was recorded for 770 pairs of mother and daughters. Between 1930 and 1990 mean menarcheal age of this cohort of women decreased from 13.88 to 12.98 years [-0.15 years per decade] and mean height of the cohort increased from 152.33 to 158.43 cm [+0.99 cm per decade]. There was a significant correlation between menarcheal age of mothers and their daughters [r = 0.27]. Year of birth, mother's menarcheal age and daughter's height were significant predictors of daughter's menarcheal age

Applications of fluorodeoxyglucose positron emission tomography in the diagnosis of infection.

The purpose of this study was to assess the accuracy of fluorodeoxyglucose positron emission tomography (FDG PET) in diagnosing infection in a large population of patients and in a variety of clinical circumstances where the performance of conventional imaging modalities has been questioned. We retrospectively analysed 167 FDG PET scans obtained to evaluate 175 anatomical sites for the presence of infection. The major indications for the scans were (1) complicated orthopaedic hardware (n=97), (2) chronic osteomyelitis (n=56), and (3) other (n=14: six fever of unknown origin, three vascular grafts, and five soft tissue). We assessed the overall diagnostic accuracy of FDG PET for each of these indications. In addition, we further analysed this modality's effectiveness by grouping the scans into specific clinical situations. A final diagnosis was made on the basis of surgical pathology and clinical follow-up for a minimum of 6 months. The overall accuracy of FDG PET in evaluating orthopaedic hardware was 96.2% for hip prosthesis, 81% for knee prosthesis, and 100% in 15 patients with other orthopaedic devices. Among the patients in our sample suspected of having chronic osteomyelitis, the accuracy was 91.2%. FDG PET was inaccurate in three cases of fever of unknown origin and accurate in all vascular graft and soft tissue infections. In 49 patients with a clinically apparent soft-tissue infection, FDG PET was able to detect or exclude underlying osteomyelitis with an accuracy of 92.3%. Among the 23 patients who had recent orthopaedic procedures, FDG PET imaging was accurate in 87% of cases. It is concluded that FDG PET is a highly effective imaging modality in the assessment of patients with suspected infection.