Radiation Control for Health and Safety Act of 1968

Radiation Control for Health and Safety Act of 1968

• Purpose of the law: To protect the public from the hazards of unnecessary radiation exposure resulting from electronic products and diagnostic x-ray equipment
• Established the Center for Devices and Radiological Health (CDRH) under the jurisdiction of the Food and Drug Administration (FDA)
• CDRH is responsible for conducting an ongoing electronic product radiation control program
• Law 90-602 only regulates equipment performance standards, not diagnostic x-ray user practices

Code of Standards for Diagnostic X-Ray Equipment

• Went into effect on August 1, 1974
• Applies to complete systems and major components manufactured after that date

As Low as Reasonably Achievable (ALARA) Concept

• Principle introduced by the NCRP in 1954
• Radiation exposure should be kept "as low as reasonably achievable" with consideration for economic and societal factors
• Described by NCRP as the continuation of good radiation protection programs and practices
• Also known as optimization
• Medical imaging personnel and radiologists share the responsibility to keep occupational and nonoccupational dose limits ALARA
• EfDs and EqDs should be well below maximal allowable levels

Dose Limits

• An EfD limiting system has been incorporated into Title 10 of the Code of Federal Regulations, Part 20
• Rules and regulations of the Nuclear Regulatory Commission (NRC) and fundamental radiation protection standards governing occupational radiation exposure are included in this document
• Basis of the EfD limiting system: concept of radiation exposure and associated risk of radiation-induced malignancy
• Resource for revised recommendations: NCRP Report No. 116 and ICRP Report No. 60
• Future radiation protection standards are expected to continue to be based on risk

Radiation Safety Committee (RSC)

• NRC mandates that an RSC be established for the facility
• Functions of the RSC: provides guidance for the program, facilitates ongoing operation of the program, and selects a qualified person to serve as a radiation safety officer (RSO)

Radiation Safety Officer (RSO)

• An RSO should oversee the program's daily operation, provide for formal review of the program each year
• Typically a medical physicist, health physicist, radiologist, or other individual qualified through adequate training and experience
• RSO has been designated by a health care facility and approved by the NRC and the state
• Responsibilities of the RSO:
  • Develop an appropriate radiation safety program for the facility that follows internationally accepted guidelines for radiation protection
  • Ensure that the facility's operational radiation practices protect people, especially those who are or could be pregnant, from unnecessary exposure
  • Review and maintain radiation-monitoring records for all personnel, be available to provide counseling for individuals
  • Employs proper safety procedures performed by qualified personnel to achieve the ALARA goal

ALARA Concept

• Procedures should be clearly described in a facility's radiation safety program
• Health care facilities usually adopt investigational levels (Level I and Level II) to define ALARA
• A facility's radiation safety program should include a description of procedures to achieve ALARA
• Goal of ALARA can usually be achieved through the employment of proper safety procedures performed by qualified personnel

Model for the ALARA Concept

• An extremely conservative model with respect to the relationship between ionizing radiation and potential risk
• Relationship is assumed to be completely linear and without any threshold
• Risk of injury should be overestimated rather than underestimated

Action Limits

• Personnel dosimeter readings should be well below a tenth of the maximum EfD limits, even for those technologists who receive the most exposure
• Health care facilities establish their own internal action limits, which are set at levels far below the actual limits
• These limits are meant to trigger an investigation that should uncover the reason for any unusually high exposure
• The RSO must be an active participant in an ongoing program designed to prevent personnel from receiving anywhere near the maximum allowed exposures

Radiation Hormesis

• Suggests a beneficial consequence of radiation for populations continuously exposed to moderately high levels of radiation
• There are numerous studies that propose a potential radiation hormesis effect
• Until the radiation hormesis theory is proven, the medical radiation industry will continue to follow the principle of ALARA for radiation protection purposes

Action Limits

• Personnel dosimeter readings should be well below a tenth of the maximum EfD limits, even for technologists who receive the most exposure.
• Health care facilities, such as hospitals, establish their own internal action limits, which are set at levels far below the actual limits.
• These limits trigger an investigation to uncover the reason for any unusually high exposure.

Radiation Hormesis

• There are numerous studies suggesting a potential radiation hormesis effect, which is a beneficial consequence of radiation for populations continuously exposed to moderately high levels of radiation.
• Advantageous genetic mutations caused by radiation exposure may have occurred during human evolution, resembling those that allow lower animals to demonstrate radiation hormesis.
• Until the radiation hormesis theory is proven, the medical radiation industry will continue to follow the principle of ALARA for radiation protection purposes.

Occupational and Nonoccupational Dose Limits

• EfD limits are established as guidelines for the protection of radiation workers and the population as a whole.
• Annual upper boundary limits are designed to limit stochastic (probabilistic) effects of radiation.
• Limits take into account the EqD in all radiation-sensitive organs found in the body.

Occupational and Nonoccupational Dose Limits (Cont.)

• Special limits are set for the crystalline lens of the eye and localized areas of the skin, hands, and feet to prevent deterministic effects.
• This is because the WT factors used for calculating EfD are so small for some organs that an organ with a low WT factor may receive an unreasonably large dose while the EfD remains within the allowable total limit.

EfD Limiting System

• Upper boundary radiation exposure limits for occupationally exposed persons are associated with risks similar to those encountered by employees in other industries considered reasonably safe.
• Radiation risks are derived from the complete injury caused by radiation exposure.

Revised Concepts of Radiation Exposure and Risk

• Changes in NCRP recommendations for limits on exposure to ionizing radiation are responsible for more recent changes in radiation protection standards.
• Many conflicting views exist on assessing the risk of cancer induction from low-level radiation exposure.
• The trend has been to create more rigorous radiation protection standards.
• Adoption of the EfD limiting system is a direct consequence of this conservatism.
• The benefit obtained from any diagnostic imaging procedure must always be weighed against the risk that is taken.

Occupational Risk

• Occupational risk associated with radiation exposure may be equated with occupational risk in other industries considered reasonably safe.
• This risk is generally estimated to be a 2.5% chance of fatal accident over an entire career.

Learn about the Public Law 90-602 of 1968, its purpose, and the establishment of the Center for Devices and Radiological Health (CDRH).