A Focused Ultrasoft X-Ray Microbeam for Targeting Cells Individually with Submicrometer Accuracy

Abstract

The application of microbeams is providing new insights into the actions of radiation at the cell and tissue levels. So far, this has been achieved exclusively through the use of collimated charged particles. One alternative is to use ultrasoft X rays, focused by X-ray diffractive optics. We have developed a unique facility that uses 0.2-0.8-mm-diameter zone plates to focus ultrasoft X rays to a beam of less than 1 microm diameter. The zone plate images characteristic K-shell X rays of carbon or aluminum, generated by focusing a beam of 5-10 keV electrons onto the appropriate target. By reflecting the X rays off a grazing-incidence mirror, the contaminating bremsstrahlung radiation is reduced to 2%. The focused X rays are then aimed at selected subcellular targets using rapid automated cell-finding and alignment procedures; up to 3000 cells per hour can be irradiated individually using this arrangement.

Development of a Soft X-ray Microprobe for Radiobiology Studies

“…-instating the MKI is based on the work done by Folkard [6,9,10] and Schettino et al [11,12]. The renovation of the MKI will provide ultra-soft X-rays to investigate spatial aspects of the interaction of ionizing with biological samples.…”

“…Currently, there are three microbeam facilities routinely used for biological experiments, which employ X-rays: two are based on laboratory bench X-ray * corresponding author; e-mail: indika.pathirana@kcl.ac.uk sources (MKII) (Queen's University Belfast and Nagasaki University, Japan) and one has been developed around synchrotron X-ray beams (Photon Factory in Tsukuba, Japan). These previous focused X-rays from continuous- Recent development of laboratory microfocus X-ray sources with ecient optics [8] is playing an increasingly important role in understanding of the mechanistic aspects of ionizing radiation eects on DNA double strand breaks [3,4,6,8]. The main challenge with this technique is the focusing of the electrons onto a small focal spot on the target to generate X-rays with small focal spot for irradiating part of cellular materials.…”

New challenges in radiobiology research with microbeams

“…However, several other applications were soon introduced and technologies rapidly improved. With the introduction of soft X-ray microbeams (Folkard et al 2001), it became possible to compare low-and high-LET radiation and to improve the subcellular resolution. Some of these new topics and their current status are summarized below.…”

A nanotube based electron microbeam cellular irradiator for radiobiology research

“…1,2 The prospect of studying the responses of cells to targeted radiation in real time provides great potential for understanding the elusive microprocesses taking place at the cellular level. Several microbeam irradiation methods have been developed, including charged particle irradiation, [3][4][5] x-ray irradiation, 6 as well as electron irradiation. [7][8][9] A charged particle microbeam system utilizes a particle accelerator to create a collimated beam of ions such as alpha particles, while an x-ray tube is commonly used to produce an x-ray microbeam through collimation.…”