The type of radiation that causes immediate tissue damage in humans is called Ionizing radiation. X-rays, gamma rays, and particle bombardment (neutron beam, electron beam, protons, mesons, and others) give off ionizing radiation. Ionizing radiation can be used for medical testing and treatment, industrial and manufacturing purposes, weapons and weapons development, and more.
Radiation sickness is generally associated with a single large exposure (acute) to Ionizing radiation and has a specific set of symptoms that appear in an orderly fashion. A series of small exposures to Ionizing radiation spread over time (chronic) are typically associated with the methods used to treat cancer and premature aging.
The degree of illness is contingent upon the amount and frequency of exposure. Symptoms may include nausea and vomiting (may vomit blood), diarrhea or bloody stool, skin-related issues such as redness, blistering, sloughing, or open sores, fatigue, weakness, tiredness, dizziness or fainting, dehydration, swelling of the exposed areas or bleeding, hair loss, easy bruising, and bleeding from the nose, mouth, gums, and rectum.