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X-ray microscopy. Instrumental and biological applications
Cell Biology
International
Reports,
Vol. 12, No. 11, November
1988
X-ray microscopy. Instrumental and Biological Applications. Edited by Ping-chin Cheng and Gwo-jen Jan. 180 Figures and 16 Plates. Springer Verlag. Berlin, Heidelberg, New York. contributions to the Symposium "X-ray comprises the This volume Microscopy '86" held in Taipei, Taiwan in August 1986. There were 99 participants from many countries. The motivation for holding the Conference in Taiwan was perhaps that construction had just begun on a 3.6 GeV synchrotron storage ring in Hsing-chu, Taiwan. The associated Synchrotron Radiation Research Centre is set to become an Tn the past, important centre for X-ray microscopy in the East. the only shadow projection methods were way to produce X-ray photographs and X-ray projection microscopy has had a long association with biological studies. For some time now, progress has been slow, but recent technological developments in X-ray sources in and image processing techniques have opened up new possibilities X-ray microscopy that seem particularly well adapted to biological investigations. High brightness electron guns with field emission cathodes can now form point sources for projection X-ray microscopy with orders of magnitude reduction of exposure time compared with thermionic cathode guns. Computer-aided data acquisition systems can also make better use of the information contained in the imaging X-rays than is possible by purely photographic methods. However, in spite of Rzntgen's authoritative statement that it would never be possible to focus X-rays, because of the low refractive index of all conceivable lens materials for X-rays, entirely new possibilities For imaging have been opened up by the emergence of dedicated high intensity synchrotron radiation sources (SRS). In such sources, a high energy electron beam travelling in a circular orbit at a speed approaching that of light, with emits a concentrated beam of X-rays considerably brightness greater directional than that 0e conventional X-ray tubes. The detailed behaviour of the X-ray emission from an SRS cannot be explained by classical physics hut relativistic wave mechanics provides plausible explanations that allow the radiated output to be optimised. The powerful X-ray beam, launched in a tangential direction to the electron path, can be channelled into suitable "beam lines" placed around the periphery gf the SRS. Tn particular, the rough1.y parallel X-ray beam in a given beam-line may be focussed to a submicrometre spot by means of a Fresnel zone plate, itself a tour de Eorce of microfabrication technology. The focussed spot can then be scanned mechanically across a specimen in raster fashion; X-rays traversing the specimen, recorded in a suitable detector, form a scanning X-ray image in a manner similar to that of a scanning electron microscope. A resolution better than 50nm. has already been demonstrated in such a microscope. Where synchrotron sources are not available, the less expensive pulsed plasma sources can be employed. The chief attraction of X-ray microscopy is that wet specimens may be examined, with a resolution better than that of the opti.c:al microscope. One way of achieving this is to choose an X-ray wavelength Eor which water, but not protein, is transparent. 0309-1651/881110995-2/$03.00/O
@ 1988Academic
Press
Lttj
996
Cell Biology
International
Reports,
Vol. 12, No. 11, November
1988
Although many of the fundamental developments in X-ray microscopy have been carried out by engineers and physicists, it seems that the time has now come for biologists themselves to play a more decisive role in devising suitable specimen preparation techniques and in learning how to interpret the resulting images. This should enable a comparison to be made with results previously obtained in critical the electron microscope. Although the electron microscope has a much better resolution, allowance has to be made in interpreting the image for dehydration and other artefacts. X-ray microscopy has now to that of the early reached a very interesting stage , quite similar days of transmission and scanning electron microscopy where at successive conferences new ideas emerge and old ideas are questioned as a result of user/designer dialogue. The present Proceedings clearly reflect this situation. Historically oriented chapters indicate how the aspirations of the early pioneers can now be realised by the new technology. Other instrumental contributions survey the basic physics and engineering behind the new technology in a straightforward way without too much technical jargon. The chapters dealing with specimen preparation technique are well illustrated and documented, with copious practical hints that should enable someone in a normal biological or chemistry laboratory to the specimen preparation procedures without too much carry out difficulty. Speculative chapters consider the pros and cons of phase contrast and amplitude contrast X-ray microscopy. For the benefit of both optimists and pessimists in the X-ray microscopy community, "X-ray the speculative chapter by E Spiller is entitled: microholography-Exciting possibility or impossible dream?" The state the point of view of both instrumentally and from of the art, biological significance, of all viable forms of X-ray microscopy, is wide-ranging well set out in this volume. An idea of the participation may be gained from a random but fairly representative selection of the laboratories represented. Department of Oral Tsurimini University, IBM Yorktown Heights Anatomy, Japan; Laboratory USA; Taiwan National University; Laboratory of Molecular Japan; SERC Daresbury Laboratory UK; Azabu University, Biology, London University UK; Australian Physics Dept. Kings College, FRG: Canadian University of G"dttingen, National University; University of Western Ontario and MC Synchrotron Research Facility; Canada; University of Winsconsin USA. The book Masters University, of biological X-ray images of properly concludes with a "Mini-atlas" prepared specimens obtained by various X-ray imaging techniques, state of the art. There is also a from which one can judge the useful list of references covering the main aspects of the subject. This book can be strongly recommended to all who have an interest It is written X-ray are curious about, microscopy. in, or to become acquainted essentially for the microscopist who wishes form of this wide-ranging and challenging with all aspects of microscopy which is now wide open for new enthusiasts to take up the various challenges now before us. T Mulvey
International
Reports,
Vol. 12, No. 11, November
1988
X-ray microscopy. Instrumental and Biological Applications. Edited by Ping-chin Cheng and Gwo-jen Jan. 180 Figures and 16 Plates. Springer Verlag. Berlin, Heidelberg, New York. contributions to the Symposium "X-ray comprises the This volume Microscopy '86" held in Taipei, Taiwan in August 1986. There were 99 participants from many countries. The motivation for holding the Conference in Taiwan was perhaps that construction had just begun on a 3.6 GeV synchrotron storage ring in Hsing-chu, Taiwan. The associated Synchrotron Radiation Research Centre is set to become an Tn the past, important centre for X-ray microscopy in the East. the only shadow projection methods were way to produce X-ray photographs and X-ray projection microscopy has had a long association with biological studies. For some time now, progress has been slow, but recent technological developments in X-ray sources in and image processing techniques have opened up new possibilities X-ray microscopy that seem particularly well adapted to biological investigations. High brightness electron guns with field emission cathodes can now form point sources for projection X-ray microscopy with orders of magnitude reduction of exposure time compared with thermionic cathode guns. Computer-aided data acquisition systems can also make better use of the information contained in the imaging X-rays than is possible by purely photographic methods. However, in spite of Rzntgen's authoritative statement that it would never be possible to focus X-rays, because of the low refractive index of all conceivable lens materials for X-rays, entirely new possibilities For imaging have been opened up by the emergence of dedicated high intensity synchrotron radiation sources (SRS). In such sources, a high energy electron beam travelling in a circular orbit at a speed approaching that of light, with emits a concentrated beam of X-rays considerably brightness greater directional than that 0e conventional X-ray tubes. The detailed behaviour of the X-ray emission from an SRS cannot be explained by classical physics hut relativistic wave mechanics provides plausible explanations that allow the radiated output to be optimised. The powerful X-ray beam, launched in a tangential direction to the electron path, can be channelled into suitable "beam lines" placed around the periphery gf the SRS. Tn particular, the rough1.y parallel X-ray beam in a given beam-line may be focussed to a submicrometre spot by means of a Fresnel zone plate, itself a tour de Eorce of microfabrication technology. The focussed spot can then be scanned mechanically across a specimen in raster fashion; X-rays traversing the specimen, recorded in a suitable detector, form a scanning X-ray image in a manner similar to that of a scanning electron microscope. A resolution better than 50nm. has already been demonstrated in such a microscope. Where synchrotron sources are not available, the less expensive pulsed plasma sources can be employed. The chief attraction of X-ray microscopy is that wet specimens may be examined, with a resolution better than that of the opti.c:al microscope. One way of achieving this is to choose an X-ray wavelength Eor which water, but not protein, is transparent. 0309-1651/881110995-2/$03.00/O
@ 1988Academic
Press
Lttj
996
Cell Biology
International
Reports,
Vol. 12, No. 11, November
1988
Although many of the fundamental developments in X-ray microscopy have been carried out by engineers and physicists, it seems that the time has now come for biologists themselves to play a more decisive role in devising suitable specimen preparation techniques and in learning how to interpret the resulting images. This should enable a comparison to be made with results previously obtained in critical the electron microscope. Although the electron microscope has a much better resolution, allowance has to be made in interpreting the image for dehydration and other artefacts. X-ray microscopy has now to that of the early reached a very interesting stage , quite similar days of transmission and scanning electron microscopy where at successive conferences new ideas emerge and old ideas are questioned as a result of user/designer dialogue. The present Proceedings clearly reflect this situation. Historically oriented chapters indicate how the aspirations of the early pioneers can now be realised by the new technology. Other instrumental contributions survey the basic physics and engineering behind the new technology in a straightforward way without too much technical jargon. The chapters dealing with specimen preparation technique are well illustrated and documented, with copious practical hints that should enable someone in a normal biological or chemistry laboratory to the specimen preparation procedures without too much carry out difficulty. Speculative chapters consider the pros and cons of phase contrast and amplitude contrast X-ray microscopy. For the benefit of both optimists and pessimists in the X-ray microscopy community, "X-ray the speculative chapter by E Spiller is entitled: microholography-Exciting possibility or impossible dream?" The state the point of view of both instrumentally and from of the art, biological significance, of all viable forms of X-ray microscopy, is wide-ranging well set out in this volume. An idea of the participation may be gained from a random but fairly representative selection of the laboratories represented. Department of Oral Tsurimini University, IBM Yorktown Heights Anatomy, Japan; Laboratory USA; Taiwan National University; Laboratory of Molecular Japan; SERC Daresbury Laboratory UK; Azabu University, Biology, London University UK; Australian Physics Dept. Kings College, FRG: Canadian University of G"dttingen, National University; University of Western Ontario and MC Synchrotron Research Facility; Canada; University of Winsconsin USA. The book Masters University, of biological X-ray images of properly concludes with a "Mini-atlas" prepared specimens obtained by various X-ray imaging techniques, state of the art. There is also a from which one can judge the useful list of references covering the main aspects of the subject. This book can be strongly recommended to all who have an interest It is written X-ray are curious about, microscopy. in, or to become acquainted essentially for the microscopist who wishes form of this wide-ranging and challenging with all aspects of microscopy which is now wide open for new enthusiasts to take up the various challenges now before us. T Mulvey