TYPES OF RADIATION
TYPES OF RADIATION
Radiation is divided into two types based on their effect on living tissue: ionizing and non-ionizing radiation.
Non-ionizing radiation is emitted by radios, televisions, cellular phones, high-voltage power lines, ultrasound and lasers. This class of radiation does not alter the electric charge of molecules (ionize them) and therefore it is considered that they do not affect health at all.
Ionizing radiation does modify the electric charges of molecules and therefore can damage tissues and affect health. The most common source of ionizing radiation, to which we are all exposed, is the environment itself that surrounds us. Small amounts of radioactive materials are found in the ground, plants, rocks and construction materials. They are miniscule quantities, but they affect us every minute of our lives.
Another daily and unavoidable exposure to radiation comes from cosmic radiation that bombards the Earth from space. Together these exposures are called background radiation. Normally a person will receive more radiation during their lifetime from background radiation than from the usual radiographic testing. Since cosmic radiation increases exponentially with altitude it is likely that any pilot during his lifetime will receive more radiation than any patient has accumulated because of diagnostic x-rays. The same can be said of anyone who lives near radioactive mineral mines like those that extract uranium or radon.
The X-rays from radiographs and scanners (CT) and the gamma rays from nuclear medicine tests and radiotherapy for cancer, are also forms of ionizing radiation.
The decisive studies related to the relationship between ionizing radiation and cancer were first done with the survivors of the atomic bombs at Hiroshima and Nagasaki. Later, studies were done with uranium miners and finally with adults whose childhood cancers were cured thanks to radiotherapy.
The general conclusion is that a relationship exists, but the risk is low. It is impossible to take enough radiographs to equal the radiation received by an uranium miner or a patient treated with radiotherapy. Yet, including in these exposed populations cancer caused by radioactivity is rare. In reality, the risk that a patient assumes when taking several dozen radiographs is miniscule.