Abstract: A new type x-ray image intensifier has a specially developed x-ray sensit photocathode which has a low/high density alkali halogenide structure and therefore has high conversion efficiency of converting x-ray directly into photoelectrons or a field-assisted x-ray photocathode which has an extracting field and therefore is able to provide a high conversion efficiency of x-ray to photoelectron and high spatial resolution, even high time resolution. The new type x-ray image intensifier consists of the x-ray photocathode, a MCP and a phosphor screen, forming a proximity focus type photoelectric imaging device.A new portable x-ray diagnosis unit has the new type x-ray image intensifier and a new type compact x-ray source that has a very small volume, 30-90 kv acceleration voltage and a cone protective cover at the outlet of x-ray.