https://padlet.com/leilaquezada26/c3bvd4mzezjac2qj en-us 2023-01-19 14:06:04 UTC 2023-01-19 14:38:33 UTC hello@padlet.com leilaquezada26 https://padlet.com/leilaquezada26/c3bvd4mzezjac2qj/wish/2449877920 1. Discuss rotating anode xray tubes. 
Rotating anode xray tubes produce heterogenous beam of radiation from a larger-diameter anode disk with focal spot sizes to facilitate the spatial resolution requirements of the scanner. It is made of rhenium, tungsten and molybdenum alloy with a small target angle of 12 degrees. Also, it has a rotation speed of 3,600 to 10,000 revolutions per minute. 
2. Discuss xray tubes in helical/spiral
A volume of tissue is scanned by moving the patient continuously through the gantry of the scanner while the x-ray tube and detectors rotate continuously for several rotations. Helical/spiral scanners sustain higher power levels, withstand additional heat generation, expand heat storage and increase heat dissipation. 
3. Discuss tube envelope, anode assembly 
The CT, x-ray tube envelope provides structural support of anode and cathode structures and high-voltage insulation between the anode and cathode. It ensures a vacuum and consists of tubes with metal envelopes. It increases storage capacity, allows for higher tube currents, and heat dissipation rate improvement. The anode assembly consists of a disk such as, a conventional all-metal disk, a brazed graphite disk and a chemical vapor deposition graphite disk. It includes a rotor—a copper cylinder brazed to an inner steel cylinder with a ceramic coating around the outside. The rotor stud and hub prevent the transmission of heat from the disk to the bearings. The bearing assembly has possible rotation speeds of 10,000 rpm. The liquid-bearing method ensures smooth rotation of the anode disk. 
4. Discuss Filtration
Filtration removes long-wavelength xrays that do not play a role in CT image formation. It produces a harder beam and reduces patient dose. Inherent filtration shapes the energy distribution across the radiation beam to produce uniform beam hardening. Added filtration in the way of beam shaping filters helps solve beam hardening effect for the CT detector system. 


]]> 2023-01-19 14:38:33 UTC https://padlet.com/leilaquezada26/c3bvd4mzezjac2qj/wish/2449877920