Absorption microanalysis with a scanning soft X‐ray microscope: mapping the distribution of calcium in bone

Abstract

SUMMARYThis article describes the scanning transmission X‐ray microscope operated at the National Synchroton Light Source. The application of the instrument to elemental analysis is detailed. In particular, qualitative results on the calcium distribution in human skull tissue are presented.

Soft X-ray microscopes and their biological applications

“…From a pair of images, one on a resonance peak, and another away from resonance, the distribution of the element can be determined. This approach was used by Kenney, Cinotti and collaborators (Kenney et al 1985;Cinotti et al 1987) to map bone calcium distribution in biopsy sections from patients suffering from osteoporosis. Recently, Buckley has further developed the calcium mapping technique on mineralized tissues to provide high signal-to-noise maps with improved quantification and sensitivity (Buckley et al 1995 a).…”

Soft X‐ray Scanning Microscopy: Its Practical Use for Elemental Mapping at the NSLS U15 Beamline

“…Moreover, calcium has large atomic resonances (near the L I11 edge, at 3.58 nm) in the region of the spectrum that is readily accessible to our microscope. To date, we have produced elemental maps of calcium with a spatial resolution of 0.2 p m , detecting concentrations of as little as S percent by weight in specimens 0.2 p. m thick (Kenney et al, 1985). Figure 2 shows some of these results.…”

A new sample preparation method for biological soft X‐ray microscopy: nitrogen‐based contrast and radiation tolerance properties of glycol methacrylate‐embedded and sectioned tissue

“…Although other investigators have used dual-and multiwavelength imaging at the carbon K-shell and calcium l-shell absorption edges to obtain contrast and map tissue components (Kenney et al, 1985;Zhang et al, 1996;Buckley et al, 1998), this is the first work to use dualwavelength imaging at the nitrogen K-shell edge in a high resolution X-ray optical microscope. Using an X-ray contact microradiographic system, Ito et al (1996) were able to obtain spectromicrographs of cultured cells across a large part of the soft X-ray spectrum (including the nitrogen edge) at a resolution comparable to that of a visible light microscope.…”

“…In general, embedding tissue in some form of matrix is needed for sectioning, although with more limitations frozen, hydrated samples can be sectioned as well. Epoxy‐embedded and sectioned mineralized samples such as bone, cartilage and calcified tendon have been imaged with element‐specific contrast in an X‐ray microscope (Kenney et al ., 1985; Buckley et al ., 1998). However, until recently, attempts to image soft tissues have had little success, apparently due to a lack of image contrast (C. J. Jacobsen, personal communication, 1999; P. Sicurello, personal communication, 1999).…”