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To introduce a new grading system of lumbar central canal stenosis, evaluate its reliabilities, and compare it to the cross-sectional area and anterior-posterior diameter of the dural sac.Lumbar central canal stenosis is defined as obliteration of the anterior CSF space in front of the cauda equina. Four musculoskeletal radiologists independently graded lumbar central canal stenosis by this new grading system based on separation degree of the cauda equina on T2-weighted axial images (grade 0 = no lumbar stenosis without obliteration of anterior CSF space; grade 1 = mild stenosis with separation of all cauda equina; grade 2 = moderate stenosis with some cauda equina aggregated; and grade 3 = severe stenosis with none of the cauda equina separated) in 81 patients to determine inter- and intra-reader reliability. One radiologist measured cross-sectional areas and anterior-posterior diameters and compared these to lumbar central canal stenosis grades.Inter-reader reliabilities were substantial to almost perfect (ICC reliability = 0.730-0.953). Intra-reader reliability was almost perfect (kappa value = 0.863-0.900). Cross-sectional areas and anterior-posterior diameters were different according to grades at all levels (p = 0.000-0.049), except between grades 2 and 3 of L2-3. At L5-S1, only anterior-posterior diameter was different between grades 0 and 1 (p = 0.005) and between grades 0 and 2 (p = 0.022).This new grading system may be helpful to clinicians for simple and practical evaluation of lumbar central canal stenosis and for communicating with each other.

Since the ICFA decision on the choice of technology, a world-wide collaboration on the design of the ILC has rapidly progressed. The formation of the GDE will accelerate the work towards a final design. An important technical challenge is obviously the high gradient acceleration but what is similarly challenging is the collision of extremely small beams of a few nanometer size. The latter challenge has three distinct issues: creating small emittance beams, preserving the emittance during acceleration and transport, and focusing the beams to nanometers. Most studies have been done using computer simulations but many issues still remain that require experimental verification. KEK-ATF was built to create small emittance beams, and succeeded in obtaining an emittance that almost satisfies the ILC requirements. In this proposal we present a project, ATF2, which addresses the third issue, namely the focusing of the beam into nanometer spot.ybr> In the longer term, the ATF2 project would also provide invaluable input for the CLIC design of a future multi-TeV collider. The ATF2 project will extend the extraction beamline of the ATF with an ILC-type final focus system to create a tightly focused, stable beam by making use of the small emittance of the ATF.