Cases of radiation induced cancer were described among scientists using x-rays before the end of the 19 th century. Interestingly, dentist William Herbert Rollins, after suffering a burned hand from radiation, became one of the first proponents of radiation safety. He subsequently developed the concept of x-ray beam collimators. During the 1920 s the dangers of ionizing radiation was taken in account and methods to reduce exposures were investigated. Most federal and state laws are based on these recommendations.
Ionizing radiation is harmful.
It produces different effects depending on total dose, the region irradiated, and the rate of administration. There is no evidence that there is a threshold below which no effect will occur. Radiation Units There is a need to measure radiation level to be able to monitor radiation exposure and measure its effects. An exposure of 1 roentgen will liberate 2.58 x 10 -4 coulombs per kilogram of air. The energy deposited by an exposure of 100 R in 1 kg of soft tissue is approximately equal to 1 Gy.