2721 Intro to Radiation Protection

When were x-rays discovered

• 1895 by Wilhelm Roentgen

• X-rays were observed to produce electrically charged particles (ions) along their path. Because of this effect the x-rays were classified as ionizing radiation

Early notable pioneers in Radiation Protection

• Thomas Edison

• William H. Rollins

Early X-ray Uses

• Shoe fitting

  • There were no applicable regulations when shoe fitting fluoroscopes were introduced

• Human Telescopes

  • A crude form of fluoroscope, became fun party toys among the elite, where they offered a new use for those Crooke’s tubes which were ever so popular novelties back then

Properties of X-rays

• Various degrees of penetration

• Invisible

• Electrically neutral - not deflected by magnetic or electric fields

• X-rays will darken film based on the amount or quantity

• Travel in straight lines and at the speed of light

• X-ray has a wide range of energies

• Cannot be focused with a lens

• Will produce charges particles by interaction and an emission of light known as fluoroescence

Two main goals of Radiation Protection

• Protecting ourselves and the community that we serve

• Cause as little biological damage as possible

As a rad tech how to we ensure radiation protection

• We are educated

• We utilize protection methods of time distance and shielding

Diagnostic Efficacy

• The degree to which the diagnostic study accurately reveals the presence or absence of disease in the patient while adhering to radiation safety guidelines

• The right exam, right site, and the right dose

ALARA

• As low as reasonably achievable

• Synonymous with the term optimization for radiation protection (ORP)

Cardinal principles

• Time

• Distance

• Shielding

Cardinal Principles: Time

• Patient

  • Reduce the amount of the x-ray “beam on” time

• Imaging Personnel

  • Shorten the length of time spent in a room where radiation is produced

Cardinal Principles: Distance

• Patient

  • Use as much distance as warranted between the x-ray tube and the patient for the exam

• Imaging Personnel

  • Stand at the greatest distance possible from an energized x-ray beam

Cardinal Principles: Shielding

• Patient

  • Always shield the patient with appropriate gonadal shielding device

• Imaging Personnel

  • Interpose a radiation absorbent shielding material between the radiographer and the source of radiation

Maintaining ALARA in Medical Industry: Facilities must have

• An effective and detailed Radiation Safety Program to ensure adequate safety of patients and radiation workers

• Individuals in executive positions must provide the resources necessary for creating and maintaining this program

• The implementation of an effective program begins with the administration of the facility

• They can:

  • Delegate operational funds in the budget

  • Oversee the development of policies and procedures

  • Provide the equipment necessary for starting and for continuing the program

Maintaining ALARA in Medical Industry: Employers Responsibilities

• Implement and maintain an effective radiation safety program in which to execute ALARA

• Make a written policy statment describing the ALARA program and identifying the commitment of management to keep all radiation exposure ALARA available to all employees in the workplace

• Perform periodic exposure audits to determine how to lower radiation exposure in the workplace

Maintaining ALARA in Medical Industry: Radiation Safety Officer

• Person in charge of making sure this plan is working and upkept

• The NRC mandates that a Radiation Safety Committee (RSC) be established for the facility

• A RSO should also be selected to

  • Oversee the program’s daily operation

  • Provide for formal review of the program each year

• An RSO is normally a medical physicist, health physicist, radiologist, or other individual qualified through adequate training and experience. This person has been designated by a health care facility and approved by the NRC and the state

• Ours is Mrs. Wells

Radiation Safety Officer

• Specifically responsible for developing an appropriate radiation safety program for the facility that follows internationally accepted guidelines for radiation protection

• They are in charge with ensuring that the facility’s operational radiation practices are such that all persons especially those who are or could be pregnant are adequately protected from unnecessary exposure

• Also must review and maintain radiation monitoring records for all personnel and be available to provide counseling for individuals

Allowable Pathways for a RSO to Meet Training and Experience Requirements

• Certification by one of the professional boards approved by the Nuclear Regulatory Commission (NRC)

• Didactic and work experience as described in detail in the regulations

• Identification as an authorized user, authorized medical physicist, or authorized health physicist on the license, with experience in the types of uses for which the individual has radiation safety officer responsibilities

Risk vs. Benefit

• Risk is the possibility of inducing adverse biologic effects such as injury to the skin or induction of cancer or a genetic defect after irradiation

• Patient will more likely accept the risk if the potential benefit to be obtained is greater than the risk involved

• Another way that radiographers can improve understanding and reduce fear and anxiety for the patient is to use the Background Equivalent Radiation Time (BERT) method

• The BERT method compares the amount of radiation received, with natural background radiation received over a specified period

• BERT is not a radiation quantity. It is a method of explaining radiation to the public. Its name is never used in the explanation

BERT

• Background Equivalent Radiation Time

• Does not imply radiation risk; it is simply a means for comparison

• Emphasized that radiation is an innate part of our environment

• Provides an answer that is easy for the patient to comprehend

Image Gently Campaign

• Although radiation dose is important for all patients, there are clear indications that children are significantly more radiation sensitive than adults. That exposure to radiation early in life, at levels found in CT and even lower, leads to a measurable increase in cancer incidence as these individuals age into 50s and 60s

• If a child receives a dose of radiation in a CT scan where adult protocols are used, the child, will receive a higher effective dose than an adult. but the image does not appear overexposed

• Campaign

  • 2008 was initiated

  • Includes dissemination of information on pediatric CT dose reduction among the various medical specialties that refer patients for CT exams or operate their own

  • Radiology departments or individual rad techs can “Pledge” to image gently. It includes

  • Make the image gently message a priority in staff communications each year

  • Review the protocol recommendations and implement adjustments to practice processes

  • Communicate openly with parents

Image Wisely Campaign

• The American College of Radiology (ACR) and the Radiological Society of North America (RSNA) formed the Joint Task Force of Adult Radiation Protection to address concerns about the increase of public exposure to ionizing radiation from medical imaging

• The Joint Task force collaborated with the American Association of Physicists in Medicine (AAPM) and the ASRT to create the Image Wisely Campaign with the objectives of lowering the amount of radiation used in medically necessary imaging studies and eliminating unnecessary procedures

Dose Limits

Exposure of the general public, patients, and radiation workers to ionizing radiation must be limited to minimize the risk of harmful biologic effects

Effective Dose (EfD)

• Scientists have developed occupational and nonoccupational effect dose limits.

• Provides a measure of the overall risk of exposure to ionizing radiation to all organs

Equivalent Dose (EqD)

• Used for radiation protection purposed

• When a person received exposure from various types of ionizing radiation

• Limits for Tissues and organs such as the lens of the eye, skin, hands, and feet

Effective Dose Limiting System

• The EfD limiting system is the current method for controlling risk of biologic damage to radiation workers and the general public from radiation exposure

Effective Dose Limit (EDL)

• The upper boundary dose of ionizing radiation that results in a negligible risk of

  • Bodily Injury

  • Hereditary Damage

Radiation Protection Standards Organizations

• There are four major organizations responsible for evaluating the relationship between radiation EqD and induced biologic effects. The following organizations are concerned with formulating risk estimates of somatic and genetic effects of irradiation

• International Commission on Radiological Protection (ICRP)

• National Council on Radiation Protection and Measurements (NCRP)

• United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)

• National Academy of Sciences/National Research Council Committee on the Biological Effects of Ionizing Radiation (NAS/NRC-BEIR)

International Commission on Radiological Protection (ICRP)

Evaluates information on biologic effect of radiation and provides radiation protection guidance through general recommendations on occupational and public dose limits

National Council on Radiation Protection and Measurements (NCRP)

Reviews regulations formulated by the ICRP and decides ways to include those recommendations in US radiation protection criteria

United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)

Evaluates human and environmental ionizing radiation exposure and derives radiation risk assessments from epidemiologic data and research conclusions: provides information to organizations such as the ICRP for evaluation

National Academy of Sciences/National Research Council Committee on the Biological Effects of Ionizing Radiation (NAS/NRC-BEIR)

Reviews studies of biologic effects of ionizing radiation and risk assessment and provides the information to organizations such as the ICRP for evaluation

US Regulatory Agencies

• After radiation protection standards have been determined, responsible agencies must enforce them for the protection of the general public, patients, and occupationally exposed personnel

• Nuclear Regulatory Commission (NRC)

• Agreement States

• Environmental Protection Agency (EPA)

• US Food and Drug Administration (FDA)

• Occupational Safety and Health Administration (OSHA)

Nuclear Regulatory Commission (NRC)

Oversees the nuclear energy industry, enforces radiation protection standards, publishes its rules and regulations in Title 10 of the US Code of Federal Regulations, and enters into written agreements with state governments that permit the state to license and regulate the use of radioisotopes and certain other material within that state

Agreement States

Enforce radiation protection regulations through their respective health departments

Environmental Protection Agency (EPA)

Facilitates the development and enforcement of regulations pertaining to the control of radiation in the environment

US Food and Drug Administration (USDA)

Conducts an ongoing product radiation control program, regulating the design and manufacture of electronic products, including x-ray equipment

Occupational Safety and Health Administration (OSHA)

Functions as a monitoring agency in places of employment, predominantly in industry

FDA White Paper

• The USFDA supports the premise that “each patient should get the right imaging exam, at the right time, with the right dose”

• This declaration is clearly state in the FDA document known as the White Paper, published in February 2010, when they announced the launch of a a cooperative initiative to reduce unnecessary radiation exposure from medical imaging

• FDA intends to take action to

  • Promote safe use of medical imaging devices

  • Support informed clinical decision

  • Increase patient awareness

Radiation Control for Health and Safety Act of 1968

• In 1968 the US congress passed the radiation control for health and safety act (public law 90-602) to protect the public from the hazards of unnecessary radiation exposure resulting from electronic products such as microwaves and TVs

• The act permitted the establishment of the Center for Devices and Radiological Health (CDRH)

• Until 1982 this organization was known as the Bureau of Radiological Health

• CDRH is responsible for setting up standards for the manufacture, installation, assembly, maintenance of machines for radiologic procedures, assessing the biologic effects of ionizing radiation, evaluating radiation emission from electronic products in general and conducting research to reduce radiation exposure

Code of Standards for Diagnostic X-Ray Equipment

• Went into effect August 1, 1974

• Applies to complete systems and major components manufactured after that date

• Equipment in use before does not need to be modified or discarded

Consumer-Patient Radiation Health and Safety Act of 1981

• Provides federal legislation requiring the establishment of minimal standards for the accreditation of education programs for persons who perform radiologic procedures and the certification of such persons

• The purpose of this federal act is the ensure that standard medical and dental radiologic practices adhere to rigorous safety precautions and standards

Limits for Non-Occupationally exposed Individuals

• The NCRP sets limits for non-occupationally exposed individuals who are not undergoing medical imaging procedures

• The NCRP recommended annual EDL is 1 mSv for continuous or frequent exposure from artificial sources other than medical irradiation and natural background and a limit of 5 mSv annually for infrequent exposure

• The 5 mSv annual limit for infrequent exposure is made because “annual exposures in excess of the 1 mSv recommendation usually to a small number of people, need not be regarded as especially significant to the group as a whole provided it does not occur often to the same groups and that the average exposure to individuals in these groups does not exceed an average annual EfD of about 1 mSv

Limits for Pregnant Radiation Workers

To reduce exposure for pregnant radiation workers and control the exposure to the unborn during potentially sensitive periods of gestation, the NCRP now recommends a monthly EqD limit not exceeding 0.5 mSv per month to the embryo fetus and a limit during the entire pregnancy not to exceed 5 mSv after declaration of the pregnancy

Limits for education and training purposes

• The limit for any education and training exposures of individuals under the age of 18 years is EfD of 1 mSv annually

• Occasional exposure for the purpose of education and training is permitted, provided special care is taken to ensure that the annual EfD limit of 1 mSv is not exceeded

Limits for Tissues and Organs Exposed Selectively or Together With Other Organs

• Annual occupational dose limits for tissue reactions, for tissues and organs exposed selectively, or together with other organs have been set to prevent excessive doses to those organs and tissues

• They include 150 mSv to the crystalline lens of the eyes and 500 mSv for localized areas of the skin, the hands and the feet

Negligible Individual Dose

To provide a low exposure cutoff level so that regulatory agencies may consider a level of effective dose as being of negligible risk, an annual negligible individual dose (NID) of 0.01 mSv/year per source or practice has been set. This means that at this EfD level, a reduction of individual exposure is unnecessary

Action Limits

• Hospital normally establish their own internal action limits

• These limits are usually set at levels far below the actual limits, typically a tenth of the limit, but at levels that are still not routinely exceeded by personnel

• The purpose of these action limits is to trigger an investigation when they are exceeded that should uncover the reason for any abnormal exposure

Radiation Hormesis

• The concept of 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 effect, which is a positive consequence of radiaiton for populations continuously exposed to moderately higher levels of radiation than ordinary background levels

• However, until the radiation hormesis theory is proven, the medical radiation industry will continue to follow a rigid principle of ALARA and the no-threshold concept for radiation protection purposes

Occupational Exposures Dose Limits

• Effective dose limits

  • Annual - 50 mSv

  • Cumulative - 10 mSv x age

• Equivalent dose annual limits for tissues and organs

  • Lens of eye - 150 mSv

  • Localized areas of the skin, hands and feet - 500 mSv

• Negligible individual dose (annual)

  • Annual - 0.01 mSv

Education and Training Exposures (Annual)

• Effective dose limit - 1 mSv

• Equivalent dose limit for tissues and organs

  • Lens of eye - 15 mSv

  • Localized areas of the skin, hands, and feet - 50 mSv

Embryo and Fetus Exposures

• Equivalent Dose Limit

  • Monthly - 0.5 mSv

  • Entire Gestation - 5.0 mSv

Public Exposure (Annual)

• Effective dose limit, continuous or frequent exposure - 1 mSv

• Effective dose limit, infrequent exposure - 5 mSv

• Equivalent dose annual limits for tissues and organs

  • Lens of eye - 15 mSv

  • Localized areas of the skin, hands, and feet - 50 mSv

• Remedial action for natural sources

  • Effective dose (excluding radon) - >5 mSv

  • Exposure to radon and its decay products - >26 (J/s)m-3