limits for exposure to ionizing radiation radl 70 kyle thornton
TRANSCRIPT
A Little Background
• Wilhelm Conrad Roentgen discovered x-rays in 1895
• In 1896, Henri Becquerel observed rays coming from a uranium containing substance
• In 1898, Pierre and Marie Curie discovered radium
More Background
• Becquerel noticed a skin reaction (erythema) 2 weeks after carrying radium in his pocket
• In 1896, hair loss was also noted from radiation exposure
• Pierre Curie exposed areas of his own skin to radium to observe the results
• The first fatality connected with radiation exposure was Clarence Daly who worked for Thomas Edison
A Little More Background
• The first safe dose was established in 1902 as 7 minutes to prevent erythema
• Shielding was rarely used• Equipment operators would demonstrate by
exposing themselves to the beam to prove it didn’t hurt
• As a consequence, early radiologists often had multiple amputations of fingers and an increased incidence of leukemia
Skin Erythema Dose
• The skin erythema dose was the unit under which there would be a negligible risk of developing erythema
• It was determined that different individuals were either less or more sensitive to radiation, therefore were more or less inclined to develop erythema
• The Roentgen was formally adopted in 1928
Organizations That Derive Standards
• UNSCEAR, BEIR– Research and report
• ICRP, NCRP, CRCPD– Report, make recommendations
• State and federal regulations, NRC, FDA, EPA, OSHA– Regulatory agencies
UNSCEAR – United Nations Scientific Committee on Effects of Atomic
Radiation• Established in 1955
• Assesses and reports on exposures to humans and the environment to ionizing radiation from natural sources, man-made practices, and accidental releases
• Findings are based on epidemiological and research findings
BEIR – National Academy of Sciences, National Research Council Committee on the
Biological Effects of Ionizing Radiation
• Advisory group to UNSCEAR
• Reviews studies of effects of ionizing radiation on humans
• Formulates reports
ICRP – International Council on Radiological Protection
• Formed in 1928• Considered to be the international authority
on the safe use of sources of ionizing radiation
• Makes recommendations to regulatory agencies based on reports from agencies such as BEIR and UNSCEAR
• Not a regulatory agency
NCRP – National Council on Radiation Protection and Measurement
• A national organization that reviews recommendations from ICRP
• Publishes reports• Not an enforcement agency, makes
recommendations• Many recommendations from this agency
are used as national radiation protection standards
CRCPD – Conference of Radiation Control Program Directors
• Established in 1968 – made up of individuals in state and local government who regulate and control the use of radiation sources
• Developed the Suggested State Regulations for Control of Radiation
Regulatory Agencies
• U.S. Nuclear Regulatory Commission (NRC)• Agreement states – 29 members, California is one
of them• U.S. Environmental Protection Agency (EPA)• U.S. Food and Drug Administration (FDA)• U.S. Occupational Safety and Health
Administration (OSHA)
NRC
• Established in the 1940’s as the U.S. Atomic Energy Commission
• Has the power to enforce radiation protection standards
• Does not regulate or inspect diagnostic imaging facilities
• Oversees the nuclear energy industry• Publishes rules and regulations in Title 10 of U.S.
Code of Federal Regulations
Agreement State
• States that have had the authority to regulate transferred to them by the NRC
• Before transfer can occur, it must be determined that the state’s radiation safety program is compatible with that of the NRC– Must protect public health and safety
EPA
• Established by the executive branch in 1970
• Oversees general area of environmental monitoring
• Provides citations for non-compliance
FDA
• Regulates the design and manufacture of electronic products by virtue of the Radiation Control Health and Safety Act of 1968
• Inspects diagnostic x-ray equipment
• Establishes specific operational standards for x-ray equipment
OSHA
• A monitoring agency in places of employment, mostly in industry
• Regulates occupational exposure to radiation
• Oversees regulations for training programs
• Oversees “right to know” regulations
State Licensure Requirements
• A voluntary process designed to ensure safe operation of radiologic equipment
• As many as half of the operators of radiologic equipment in the U.S. are not certified
• Most studies have proved that licensed operators provide better radiation protection
• The goal is to ensure that operators meet minimum safety standards thereby delivering quality patient care
Radiation Safety Officers and Medical Physicists
• A designated person in an institution approved by the NRC and the state
• Ensures that accepted guidelines for radiation protection are observed and practiced in that institution
• Responsible for the formation of the institutional Radiation Safety Program
Effective Dose Equivalent Limiting System
• Current method for assessing radiation exposure and associated risk to radiation workers and the general public
• The threshold dose that results in a negligible risk of bodily injury or genetic damage
Radiation Control Health and Safety Act of 1968 – Public Law
90-602• Enacted to protect the public from the hazards of
unnecessary radiation exposure from electronic equipment– Includes microwave ovens, color TV’s and diagnostic
x-ray equipment
• Falls under the jurisdiction of the FDA• Includes minimum standards for the manufacture,
installation, assembly, and maintenance of machines used for radiologic procedures
Code of Standards for X-Ray Equipment Since August 1, 1974• Positive beam limitation• Minimal permanent filtration• Exposure reproducibility and linearity• Beam limitation devices for fluoroscopic
spot films• Presence of beam-on indicators• Inclusion of manual backup timers for AEC
should the phototimer fail
Consumer-Patient Radiation Health and Safety Act of 1981 – Title 9 of Public
Law 97-35• Established minimal standards for accreditation of
educational programs for persons who administer radiologic procedures– and
• The certification of such persons• This was to ensure that medical/dental procedures
are consistent with safety precautions and standards
• No penalty exists for state non-compliance
Non-Stochastic Effects
• Deterministic effects• There is a threshold dose for these effects• Early effects – erythema, decreased WBC
count, epilation• Early serious effects – hematopoietic
syndrome, GI syndrome, cerebrovascular syndrome– Acute radiation syndrome
Non-Stochastic Effects
• Late effects– Cataracts– Fibrosis– Organ atrophy– Reduced fertility– Sterility– Loss of parenchymal cells
Stochastic Effects
• Non-threshold, randomly occurring effects
• Includes cancer, and genetic effects
NCRP Recommendations
• TEDE – Total effective dose equivalent– 5 rem annually (50 mSv)
• TED – Lifetime total effective dose– Should not exceed 10 mSv or 1 rem times that
person’s age
Radiation Hormesis
• A beneficial consequence of constant exposure to radiation exposure
• Based on information from many studies• Follows lower-life form animals• Radiation induced mutations that are
advantageous have occurred, i.e., lower incidence of cancer than that of the general population