Chapter 8 - Dose & Policy
Dose Limits, ALARA and Dosimetry Requirements (Top)
The following table contains terminology associated with this Chapter.
||Used in determining internal exposures, referring to the dose being based on the amount which would be received over the following 50 years to account for doses received later in life from radionuclides still in the body.|
||Hand, elbow, arm below the elbow, foot, knee, and leg below the knee|
||Committed Dose Equivalent
||Dose to individual organs or tissues received over a 50 year period after a radiosotope is inhaled, ingested, or otherwise entered into the body weighted for its effect on the whole body|
||Committed Effective Dose Equivalent
||Sum of doses to organs or tissues, received over a 50 year period after radioisotope is inhaled, ingested, or otherwise entered into the body weighted for its effect on the whole body|
||Deep Dose Equivalent
||External radiation exposure to tissue at a depth of 1 cm|
||Eye Dose Equivalent
||External dose to the lens of the eye at a tissue depth of 0.3 cm|
External to the skin or an extremity at a tissue depth of 0.007 cm averaged over a
1 cm2 area
||Total Effective Dose Equivalent
||Sum of doses received from external sources to the most highly exposed part of the whole body (DDE) and from radionuclides inside the body weighted for its effect on the whole body (CEDE)|
||Total Organ Dose Equivalent
||Sum of doses to individual organs or tissues from external sources (DDE) and from radionuclides inside the body (CDE)|
||Head, trunk (including male gonads), arms above the elbow, and legs above the knee|
Personnel exposure to radiation in any one calendar year must be kept as low as reasonably achievable (ALARA) and specifically below the maximum permissible doses as listed in the following table. (The Maximum Permissible Dose for radiation workers under age 18 is 10 percent of the listed values and the CU ALARA Guidelines apply as listed.) Doses received which exceed the “CU ALARA Guidelines” in the policy are investigated by the RSO and reported to the RSC. The investigation includes the determination of the dose’s source, if the dose was truly received by that individual, and if proper dose reduction techniques have been used.
Anyone with questions or concerns about potential doses or risks may contact EHS at any time.
|Whole body (WB) total effective dose equivalent (TEDE) from internal (CEDE) and external (DDE) sources
Total organ dose equivalent (TODE) from internal (CDE)
and external (DDE) sources
|Lens of the eye dose equivalent (LDE)
Skin, hands, forearms, elbows, knees, leg below the knee, feet and ankles shallow dose equivalents (SDE)
Embryo/Fetus (See following discussion on
declared pregnancies in section 8.3)
|500/gestation period for a declared pregnancy
|Non-radiation workers (non-users), including members of the public
8.3 Pregnant Radiation Workers (Top)
The manner in which the dose limits for the embryo/fetus is handled is at discretion of the pregnant radiation worker. Pregnant radiation workers are encouraged to advise their permit holder and the RSO of any situation that could result in fetal radiation exposure, so that the adequacy of radiation safety precautions can be assessed and pertinent information can be provided to the worker. Information and counseling may be requested at any time from the RSO. Counsel from a reproductive health specialist may be requested (because it is believed that the period of greatest radiation sensitivity for a fetus is from weeks 10 to 17, this assessment should be done as soon as possible). Four options are available to pregnant radiation workers.
8.3.1 Pregnant workers may choose to officially declare their pregnancy, which restricts the dose to the embryo/fetus to 500 mrem during the gestation period. This could result in restrictions in the types of work the declared pregnant worker is allowed to perform. To declare a pregnancy, the worker must submit to her permit holder a "Declaration of Pregnancy" form (available from the RSO) or any other written declaration that states her approximate date of conception and that she wishes to be treated as a pregnant radiation worker for purposes of this section. Declarations of pregnancy may be made at any time during the pregnancy.
8.3.2 Pregnant workers may choose not to declare their pregnancy. If a pregnant worker does not declare her pregnancy, according to NYS DOH regulations, the dose restriction of 500 mrem to the embryo/fetus does not apply, (i.e. the embryo/fetus could have the potential to legally receive a total effective dose equivalent (TEDE) up to 5,000 mrem). If a worker decides not to declare her pregnancy, no restrictions in the types of work she may perform can be imposed based on her pregnancy. The option not to declare is to protect the worker from possible discrimination due to restrictions in work activity. Until a worker officially declares a pregnancy, Cornell University, by law, must assume she is not pregnant.
8.3.3 A radiation worker may declare herself pregnant when, in good faith, she believes there is a potential that she may be pregnant, but her pregnancy has not been confirmed, by following the same procedure for declaring a pregnancy. When the radiation worker has confirmed her pregnancy, she must notify her permit holder and provide any revised estimated date of conception. A declaration of pregnancy will expire ten months after the declared estimated date of conception, unless it has been revised.
8.3.4 A radiation worker who has previously declared herself pregnant may revoke the declaration of pregnancy at any time, in her sole discretion. Since declaration of pregnancy will expire ten months after the declared estimated date of conception, the radiation worker need not revoke her declaration after the expiration date.
Every effort must be made to avoid substantial variation above a uniform monthly dose rate to a declared pregnant woman. If at the time of declaration, the dose to the embryo/fetus has exceeded 450 mrem since the estimated date of conception, the embryo/fetus will be limited to a dose of no more that 50 mrem for the remainder of the pregnancy. The declared pregnant radiation worker must be required to wear a radiation badge in the abdominal region to evaluate doses to the embryo/fetus separately from the doses to the chest. The fetal badge must be worn under any protective clothing and the badging frequency must be monthly.
It is important for pregnancy workers to understand that fetal dose from any beta emitters, including P-32, will be zero from all external exposures. The only way to exposure the fetus is through radioactive material taken into the body (internal contamination), or from exposure to photon sources (gamma or x-rays) or neutron sources.
Individuals involved in the following activities must wear the prescribed monitoring equipment, such as badges and rings, as required by the provisions listed below:
18.104.22.168 Operators and users of x-ray diffraction equipment used in an open beam configuration must wear a whole body badge and a ring badges.
8.4.1 Badge requirements for ensuring that doses are maintained ALARA for anyone handling radioactive materials, sealed or unsealed, are the following:
22.214.171.124 Users of beta emitters with energies less than 200 keV are not required to wear badges, because these energies are too low to be measured by these devices.
126.96.36.199 Users of beta emitters with energies greater than or equal to 200 keV and an activity of 1 mCi or greater must wear a whole body badge and a ring badge on each hand.
188.8.131.52 Users of any gamma emitter with an activity of 1 mCi or greater must wear a whole body badge and a ring badge on each hand.
8.4.2 Users of RPE must wear badges for ensuring that doses are maintained ALARA under the following conditions:184.108.40.206 Operators and users of x-ray diffraction equipment used in an open beam configuration must wear a whole body badge and a ring badges.
220.127.116.11 Individuals who work near accelerators who could be exposed to a dose rate in excess of 2.0 mrem/h must wear a whole body badge.
18.104.22.168 Individuals who remain in the room during the use of radiographic equipment must wear a whole body badge.
8.4.3 Any individual who performs veterinary fluoroscopic procedures must wear a whole body badge and a ring badge on each hand in compliance with NYS DOH regulation.
8.4.4 Any individual who holds animals or films during veterinary radiography must wear a whole body badge in compliance with NYS DOH regulation.
8.4.5 Anyone working in areas greater than 2.0 mrem/h must wear a whole body badge to ensure that doses are maintained ALARA.
8.4.6 Any individual entering high or very high radiation areas must wear a whole body badge for compliance with NYS DOH regulation.
8.4.7 Any individual who is likely to receive an external dose in excess of ten percent of the applicable "Maximum Permissible Dose" specified in section 8.2 of this chapter must wear badges appropriate to the type of dose for compliance with NYS DOH regulation.
8.4.8 Individuals who do not fall within these categories may be issued a whole body badge or both a whole body badge and a ring badge for each hand upon request. Ring badges will not be issued without a body badge, and rings will always be issued in pairs.
A BODY BADGE IS USED WITH RINGS IN THE EVENT SOME WORK IS NOT DONE BEHIND A BETA SHIELD OR CONTAMINATED EQUIP NEEDS TO BE CLEANED. Also the body limit is lower than the hand dose limit so it is possible that the body limit could be exceeded before the hand limit.
8.4.9 Monitoring frequency, normally two-month periods, must be at the discretion of the RSO.
8.4.10 Badges, except visitor badges, issued for any reason, whether required or requested, must be worn whenever a possibility for exposure exists, i.e. whenever near any source of radiation.
8.4.11 The RSO may modify the requirements above based on potential exposure assessments and the likelihood of actual exposures. For example, the use of extensive body and finger shielding with high activity P-32 may result in very low actual exposures. In this case dosimetry may not be needed.
8.5.1 Access to an individual's dose records must be restricted to that individual and to individuals with responsibility for ensuring radiation safety at the University. These individuals include the RSO, the RSC members, the badged individual's permit holder, department safety offier, principal investigator, and/or supervisor and their designees. Access to other parties may be granted only with written authorization from the badged individual.
8.5.2 Doses for each calendar year will be made available online to each badged individual. Except when required by a regulatory agency, individuals who leave Cornell prior to receiving the report have the option to receive one if they provide a forwarding address to the RSO. Except when required by a regulatory agency, visitors will not be sent a report unless one is specifically requested in writing to the RSO.
8.5.3 Individuals may obtain their dose records at any time upon written request to the RSO.
8.5.4 Individuals who have been monitored previously at other institutions must provide a cumulative record of previous radiation exposure to the RSO or authorization (including an address) for the RSO to request those results from the other institution.
8.5.5 Individuals monitored at other institutions during the current calendar year must provide the radiation exposure results from the other institution in writing to the RSO as soon as they are available.