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Rad Protection Ch.10
Dose Limits for Exposure to Ionizing Radiation
| Question | Answer |
|---|---|
| Dose Limits | - Exposure of the general public, patients, and radiation workers to ionizing radiation must be limited in order to minimize the risk of harmful biologic effects. |
| Dose Limits: | - Occupational and nonoccupational effective dose (EfD) limits and equivalent dose (EqD) limits for tissues and organs such as the lens of the eye, skin, hands, and feet have been developed for radiation safety purposes. |
| Effective Dose Limiting System | A set of numerical dose limits that are based on calculations of various risks of cancer and genetic effects to tissues or organs exposed to radiation. |
| International Commission on Radiological Protection (ICRP) | - Authority of regarding the safe use of sources of ionizing radiation. - They make recommendations, but do not become the enforcement agency. |
| National Council on Radiation Protection and Measurements (NCRP) | - Reviews recommendations formulated by the ICRP. - Determine how recommendations are incorporated in the US. |
| United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) | - Evaluates human & environment ionizing radiation exposures from radioactive materials, radiation producing machines & radiation accidents. - They use epidemiologic data (atomic bomb survivors) and research conclusions to determine risk. |
| National Academy of Sciences/National Research Council Committee on the Biological Effects of Ionizing Radiation (NAS/NRCBEIR) | Advisory group that reviews studies of biological effects (routinely or accidentally exposed) and reports to organizations such as the ICRP for evaluation. |
| Nuclear Regulatory Commission (NRC) | - Federal agency that has the power to control the possession, use and production of atomic energy in the interest of national security. - Their main function is to oversee the nuclear energy industry. |
| Agreement States | - They assume responsibility to enforce radiation protection regulations. - If you are not in an agreement state, the NRC sends agents to inspect equipment. |
| States who have entered into an agreement with the NRC to inspect radiographic equipment and design. | Agreement States. |
| Environmental Protection Agency | Development and enforcement of regulations pertaining to the control of radiation in the environment. |
| EPA also | - Directs federal agencies. - Oversees the general area of environmental control. - Determines actions for RADON levels. |
| Occupational Safety and Health Administration | Monitoring agency concerning the "right to know" of employees with regard to hazards that may be present in the workplace. |
| What are international organizations that deal with radiation safety? | ICRP, NCRP. |
| Radiation Safety Program | - Delegate operational funds. - Oversee development of policies and procedures. - Provides necessary equipment for program. |
| Radiation Safety Committee | NRC mandates that a radiation safety committee be established for facilities to assist in the development of the radiation safety program. |
| Radiation Safety Officer | - Compliance with federal and state guidelines. - Develops radiation safety program. - Maintains records. - Training required. Ex: Medical physicist, health physicist or radiologist. |
| RSO is normally a : | - Medical physicist. - Health physicist. - Radiologist. - Other individual qualified through adequate training and experience. |
| An RSO should : | - Oversee the program's daily operation. - Provide for formal review of the program each year. |
| ________ has been designated by a health care facility and approved by the NRC and the state. | RSO. |
| Radiation Control for Health and Safety Act of 1968 | - Act passed by U.S. Congress in 1968. - Public Law 90-602. |
| Radiation Control for Health and Safety Act of 1968 Purpose of law: | - To protect the public from the hazards of unnecessary radiation exposure resulting from electronic products and diagnostic `x-ray equipment. - Act permitted the establishment of the Center for Devices and Radiological Health (CDRH). |
| Radiation Control for Health and Safety Act of 1968 Reasons of Law: | - Protect public for hazards of unnecessary radiation exposure resulting from such products as microwaves and tv. - Diagnostic equipment is also included. |
| Consumer-Patient Radiation Health and Safety Act of 1981 | Requires minimal standards for accreditation of education programs for those who perform radiographic procedures. |
| Radiation Hormesis: | Is that there exists a beneficial aspect or result to groups of individuals from continuing exposure to small amounts of radiation. |
| Radiation Hormesis | - Hypothesis that a positive effect exists for certain populations that are continuously exposed to moderate levels of radiation. - Not proven. |
| Action Limits | - Healthcare facilities have to set their own internal standards for a dose of radiation in which they consider and action limit. - Usually 1/10 the maximum dose limit - Designed so that the maximum dose for employees will not be reached. |
| Occupational Dose Limits | 50mSv (5 rem) per year whole body occupational dose limit. |
| Negligible Individual Dose | 0.01mSv/yr. |
| Tissues & Organs | - 150mSv (15 rem) to the lens of the eyes. - 500mSv (50 rem) skin, hands & feet. |
| Pregnant Female Radiation Workers | Monthly dose not exceeding 0.5 mSv (0.05 rem) per month to the embryo-fetus and a limit during the entire pregnancy 5.0mSv (.50 rem). |
| Non-occupational Exposure | - Spouse, parent or guardian with a patient. - 1mSv (0.1 rem) for continuous exposures from artificial sources and 5 mSv (0.5 rem) annually for infrequent exposure. |
| ICRP revision for Annual Effective Dose: | Want reduction of annual effective dose limit for occupationally exposed persons from 50mSv to 20mSv. |
| 1.ICRP revision for Annual Effective Dose: | 1.The revised risk estimates derived from the recent reevaluations of dosimetric studies on the atomic bomb survivors. 2.The appearance of increase numbers of solid tumors in the survivors. |
| Annual Occupational Effective Dose | - 50mSv 5 rem (not including medical & natural background exposure). - With the recommendation the lifetime effective dose should not exceed 10 times the occupationally exposed person's age in years. |
| 1.Determination of potential risk: | 1.The tissue weighting factor was put into place because tissues and organs do not have the same degree of sensitivity. |
| 2.Determination of potential risk: | 2.This indicates the ratio of the risk of stochastic effects attributable to irradiation of a given organ or tissue to the total risk when the whole body is uniformly irradiated. |
| Cumulative (Lifetime effective dose) | 10mSv times age (age times 1 rem) and pertains to whole body. |
| Effective Dose Limiting System | - Method for assessing radiation exposure and risk of biological damage. - Determines the upper boundaries for "safe" exposure to ionizing radiation. - Takes into account exposure and risk, occupational risk and radiation exposure to Embryo-Fetus. |
| Current Radiation Protection Philosophy | - No amount of radiation is "safe" (Linear non-threshold). - Ionizing radiation posses a beneficial and a destructive potential. - Benefits must outweigh the risk. |
| Basis of the Effective Dose Limiting System | Any organ is vulnerable. |
| Objectives of Radiation Protection: | - By adhering to dose limits that are beneath the threshold levels. - To a conservative level as weighed against societal needs, values, benefits acquired and economic considerations. |
| ALARA | - Established in 1954. - Accepted by all regulatory agencies in 1987. - As low as reasonably achievable. |
| ALARA: | - Techs and radiologists share responsibility. - Keeps occupational and non-occupational dose limits ALARA. - Also known as Optimization for Radiation Protection (ORP). |
| Objectives of Radiation Protection: | - To prevent non-stochastic effects. - To limit risk of stochastic effects. |
| Tissue Reactions | - Formally called Non-stochastic response. Is a deterministic response: - May be categorized as an early effect or a late effect. - The amount of radiation and body part exposed determines the effect. |
| Stochastic Effects | - Probabilistic effects. - Randomly occurring biologic somatic changes. |
| 1.CODE OF STANDARDS FOR DIAGNOSTIC XRAY EQUIPMENT: | 1. - Established in 1974, equipment made prior is exempt from law. - Positive beam limitation. - Minimum filtration. - Reproducibility (consistency - variations of 5% or less is acceptable.). |
| 2.CODE OF STANDARDS FOR DIAGNOSTIC XRAY EQUIPMENT: | 2. - Beam limitations for spot films, - Indicators for visible warnings when x-rays are in progress. - Back up timer to control the stopping of exposure. |
| Consumer-Patient Radiation Health and Safety Act of 1981 | Requires minimal standards for accreditation of education programs for those who perform radiographic procedures. |
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