AP chest x-rays are harder to read than PA x-rays and are therefore generally reserved for situations where it is difficult for the patient to get an ordinary chest x-ray, such as when the patient is bedridden. In this situation, mobile X-ray equipment is used to obtain a lying down chest x-ray (known as a supine film).
An MRI system requires helium to keep its magnet cool, especially when imaging a patient, and continues to consume helium to remain cool when the magnet is idling. An MRI system must be cooled to 4.2 K, or -452Â° F, and liquid helium is the most effective way to sufficiently cool the magnet to that temperature.
Because liquid nitrogen instantly freezes anything on contact, dermatologists can use it to simply dry out unwanted tissue and let it fall off. Surgeons also use cryotherapies to eliminate cancerous cells. In the kitchen, liquid nitrogen is used to make ice cream, flash-freeze herbs or freeze alcohol. Bartenders will swirl it around glasses to chill them, so that the supercooled glass will emanate a dramatic-looking vapor. (Liquid nitrogen creates a fog when exposed to air.)