Digital X-ray imaging technology has advanced rapidly over the past few years. This review, particularly aimed at those involved in using and purchasing such technology, is an attempt to unravel some of the complexities of this potentially confusing subject. The main groups of X-ray imaging devices that are considered are digitisers of conventional radiographs, image-intensifier-based fluorography systems, photostimulable phosphor computed radiography, amorphous selenium-based technology for thorax imaging and flat-panel systems. As well as describing these different systems, we look at ways of objectively assessing their image quality. Concepts that are used and explained include spatial resolution, grey-scale bit resolution, signal-to-noise ratio and detective quantum efficiency. An understanding of these basic parameters is vital in making a scientific assessment of a system's performance. Image processing and techniques are also briefly discussed, particularly with reference to their potential effects on image quality. This review aims to provide a basic understanding of digital X-ray imaging technology and enables the reader to make an independent and educated assessment of the relative merits of each system.

1415 This is the first report on cryopreservation via PVS2 vitrification method on roses using in vitro 16 fragmented explants (IFEs) as the starting material. The aim of this study is to optimize the efficient 17 plant recovery and regeneration system for cryopreservation of Rosa hybrida cv. Helmut Schmidt 18 using IFEs. Some important parameters have been optimized in this study are the effect of ascorbic 19 acid (0.3 mM) examined separately and in combination at all steps in cryopreservation procedure 20 (preculture, loading, unloading and growth recovery), loading type, loading duration, and PVS2 21 duration. The highest growth recovery of 43.33% was obtained when 3-4 mm size IFEs precultured 22 on 0.25 M sucrose media supplemented with full-strength MS for one (1) day, followed by loading 23 treatment supplemented with 1.5 M glycerol + 0.4 M sucrose + 5% DMSO + 0.3 mM ascorbic acid 24 for 20 minutes, dehydration with PVS2 solution for 30 minutes and then treated with unloading 25 solution supplemented with 1.2 M sucrose + 0.3 mM ascorbic acid for 20 minutes. This finding 26 implies that long-term storage of Rosa Hybrida cv. Helmut Schmidt by PVS2 vitrification method 27 was successful with essential biomolecules. 28 29 30 Keywords: In vitro fragmented explants (IFEs), PVS2 vitrification, ascorbic acid, Biomolecules, 31 Rose 32 34 Roses are one of the most important ornamental plants in many parts of the world. This 35 is because they bloom beautiful flowers and as such, they are widely used in the horticultural 36 industry. Cultivation of rose plants via tissue culture micropropagation has disadvantages in 37 terms of contamination, somaclonal variations and also due to biotic stresses [1]. Hence, 38 cryogenic storage offers a stable and safe method for long term storage of plant materials 39 while safeguarding genetic stability [2]. Cryopreservation at temperatures of -196°C has been 40 considered as an ideal means for long term storage of plant germplasm. Through 41 cryopreservation, hybrids that are in danger of being extinct can be conserved with low 42 maintenance apart from being easy for international exchange. Cryopreservation through 43 vitrification reduces injury caused by intracellular crystallization and provides high 44 regeneration rates prior to immersion into liquid nitrogen. Basically, the most appropriate 45 plant part utilized is the meristem culture since it generates virus free lines [3]. For PVS2 46 cryopreservation study in roses, in vitro fragmented explants (IFE) represent a new source of 47 explant as starting material. IFEs were first introduced by authors [4] who conducted research 48 on Vanilla planifolia "Andrews". The study discovered that IFEs allows the production of a 49 larger number of shoots than micro cuttings after 4 months in culture. However, every 50 species of plants has different genetic makeup and respond differently to various treatments. 51 Therefore, improvement of the cryopreservation method is crucial in each step for growth 52 after recovery. Vitrification ...

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