FAQ

This is untrue. We probably know more about radiation than any other cancer-producing agent (carcinogen), physical or chemical. Experience goes back about 80 years and the information is probably better documented than that for any other carcinogen. Radiation is, in fact, a relatively weak carcinogen and mutagen.
This is untrue. Radiation is not very effective in causing cancer and even in large populations exposed to high doses of radiation the increase over the normal cancer rate is small. For instance, follow-up studies (through 1978) of 82,000 exposed Japanese A-bomb survivors have produced an estimated 250 radiation-induced cancers.
This is almost always untrue. For individual patients undergoing radiologic procedures related to illness, the benefits of the procedure far outweigh the risks.
No. The radiation dose required to sterilize (500-600 rems) is at least a factor of 100 larger than the gonadal radiation exposure from "several" x-ray exams, even if the exams are directly of the gonadal area. If the x-ray exams are directed at other regions, the radiation exposure to the gonads would be even less.
With the very small amounts of radiation by persons working with x-rays and with the small amounts delivered to patients in typical diagnostic x-ray or nuclear medicine examinations, we expect nothing to happen to patients or personnel. Studies of persons occupationally exposed to x-rays or gamma rays for the past 30 years have not shown an increase in cancer.
The mean lethal dose (L.D. 50/30), or the dose that wound be lethal to 50% of the human population within 30 days after irradiation, is approximately 350 rems of x-rays or gamma rays given in a single exposure to the whole body. The minimum lethal dose which may cause death in a few percent of exposed persons is probably about 250 rems. The mean lethal dose will be considerably higher if only part of the body is irradiated or if the irradiation is spread out over a longer time period, such as 1 week. The administration of special medical care, including infection control and bone marrow transplants, will also increase the LD 50/30.
Obvious injury such as skin burn, loss of hair and cataracts may be produced after doses of several hundred rems have been received in a short time such as one day. At low doses such as a few rems the only possible injury is long delayed cancer, but the possibility is very small. Depending on the assumption made, the risk has been estimated by expert committees as about 2 in 10,000 persons over a lifetime after receiving 1 rem of radiation dose to the entire body.
The "danger" to which an x-ray technician is exposed, resulting from contact with radiation during a working lifetime, is very small. If the typical radiation exposure of about 0.5 rem per year is received, no observable effects are expected.
This is not clearly known but may be true. Even very small amounts of ionizing radiation can produce damage at the sub-microscopic level in some of the exposed cells. Whether this damage affects the properties of the cell, such as its ability to divide or its transformation to a malignant form, depends or many factors including where the damage occurs, the extent of the damage, and healing ability of the cell. It is clear, however, than the malignant transformation of a cell is extremely unlikely at low doses.
In the great majority of persons there is no evident effect, immediate or delayed. However, there is a very small chance that cancer may develop after a delay of several or many years, and that genetic effects may appear in future generations.

The acceptable level depends on who you are, where you are, your age, and a judgment on whether that level can readily be reduced. There are maximum permissible exposure levels which have been promulgated by the International Commission on Radiological Protection and in the USA by the National Council on Radiation Protection and Measurements. These recommended levels have been endorsed by various federal agencies such as the Nuclear Regulatory Commission, by State governments and by numerous employers. There are dose limits for the whole body and for specific organs of the body. The limits are different for persons who are occupationally exposed and persons who are not occupationally exposed but are in the vicinity of radiation sources; for the whole body these limits are 5 rem per year and 0.1 rem per year, respectively. The limit to persons younger than 18 and the fetus in occupationally exposed pregnant women is 0.5 rem per year.

Very few occupationally exposed persons receive the 5 rem limit per year. The national average for occupationally exposed persons is less than 0.5 rem per year. All such persons carry a radiation monitor. It is a requirement of the Nuclear Regulatory Commission that radiation doses received occupationally must be reviewed periodically by radiation safety personnel and that efforts be made to maintain such doses at levels which are "as low as reasonably achievable."

These maximum levels were arrived at by considering combined cancer and genetic risk from radiation and choosing a dose level such that radiation work would carry a risk comparable with the less hazardous occupations in our society. The general public limit has been set somewhat arbitrarily at 50 times less than the occupational limit with an average to the whole population not to exceed 170 millirem per year which is somewhat less than an additional background dose.

Please note that all information about Radiation Safety Training and the ability to register for this training is now available by going to the EHS training website.