Compact X-Ray Tube With Ceramic Vacuum Seal for Portable and Robust Dental Imaging

A major challenge for glass X-ray tube makers is the reduction in the tube size for portable or handheld applications. Size reduction is difficult mainly due to contact size restrictions for glass-to-metal welding. In high-voltage (60-70 kV) portable applications such as dental imaging, a distance of at least 5 mm should be maintained between the anode and the glass envelope to prevent the latter from burnout, which further limits reduction in the tube's diameter. In this study, reduction in the size of a dental X-ray tube by approximately 43% is achieved by replacing the glass envelope with ceramic. Instead of welding, the ceramic body permits the use of brazing, which supports extremely small contact sizes. Additionally, due to the higher dielectric constant of ceramic, even less than 1 mm spacing is permissible between the envelope and the anode, enabling further size reduction. Despite the 43% reduction in size, limiting spatial resolutions of approximately 8 and 7 lines per mm are obtained for the ceramic and glass sealed tubes, respectively. Moreover, the two tubes obtain similar X-ray images of human teeth, verifying the potential of the compact-size ceramic X-ray tube in dental imaging.