U.S. NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REGULATORY RESEARCH
REGULATORY GUIDE 8.18
(Draft was issued as DG-8037, dated May 2009)
INFORMATION RELEVANT TO ENSURING THAT RADIATION
EXPOSURES AT MEDICAL INSTITUTIONS WILL BE
AS LOW AS IS REASONABLY ACHIEVABLE
This guide is directed specifically toward medical licensees and recommends methods that the
staff of the U.S. Nuclear Regulatory Commission (NRC) considers acceptable to maintain exposures as
low as is reasonably achievable (ALARA) in medical institutions. In a medical institution, certain
persons other than employees are exposed to radiation from licensed radioactive material. These persons
include visitors and patients other than those being treated with radioactive material. This guide
addresses the protection of these individuals. The content of this guide is also applicable to veterinary
medical institutions, insofar as specific diagnostic or therapeutic procedures are performed. Similar
protection practices apply for keeping employee and visitor exposures ALARA, whether the patients are
animal or human.
The regulatory framework that the NRC has established for medical licensees includes Title 10,
Section 20.1101(b), of the Code of Federal Regulations (10 CFR 20.1101(b)) (Ref. 1). In this regulation,
the NRC states that the licensee shall use, to the extent practical, procedures and engineering controls
based on sound radiation protection principles to achieve occupational doses and doses to members of the
public that are ALARA. Regulatory Guide 8.10, “Operating Philosophy for Maintaining Occupational
Radiation Exposures as Low as Is Reasonably Achievable,” issued May 1977 (Ref. 2), provides guidance
for the philosophy and general management policies and programs that licensees should follow to
maintain radiation exposures to employees ALARA. NUREG-1556, Volume 9, Revision 2,
“Consolidated Guidance about Materials Licenses: Program-Specific Guidance about
Medical Use Licenses,” issued January 2008 (Ref. 3), includes information on an acceptable management
program for keeping exposures ALARA, as well as specific examples of radiation protection programs
The NRC issues regulatory guides to describe and make available to the public methods that the NRC staff considers acceptable
for use in implementing specific parts of the agency’s regulations, techniques that the staff uses in evaluating specific problems
or postulated accidents, and data that the staff needs in reviewing applications for permits and licenses. Regulatory guides are not
substitutes for regulations, and compliance with them is not required. Methods and solutions that differ from those set forth in
regulatory guides will be deemed acceptable if they provide a basis for the findings required for the issuance or continuance of a
permit or license by the Commission.
This guide was issued after consideration of comments received from the public.
Regulatory guides are issued in 10 broad divisions: 1, Power Reactors; 2, Research and Test Reactors; 3, Fuels and Materials
Facilities; 4, Environmental and Siting; 5, Materials and Plant Protection; 6, Products; 7, Transportation; 8, Occupational Health;
9, Antitrust and Financial Review; and 10, General.
Electronic copies of this guide and other recently issued guides are available through the NRC’s public Web site under the
Regulatory Guides document collection of the NRC’s Electronic Reading Room at http://www.nrc.gov/reading-rm/
doc-collections/ and through the NRC’s Agencywide Documents Access and Management System (ADAMS) at
http://www.nrc.gov/reading-rm/adams.html, under Accession No. ML102350460. The regulatory analysis may be found in
ADAMS under Accession No. ML10102350474.
and practices acceptable to the NRC’s licensing staff. For recommendations on ALARA levels for
effluents from medical facilities, please refer to Regulatory Guide 8.37, “ALARA for Effluents from
Materials Facilities” (Ref. 4).
Specific guidance on radioactive materials in effluents to unrestricted areas is beyond the scope of
this guide. This topic is mentioned only in connection with actions that influence both occupational
exposure and effluent control. NUREG-1556, Volume 9, provides further details on this subject. In
addition, this guide addresses only radioactive materials subject to licensing by the NRC. The regulations
and recommendations of other agencies should be consulted in regard to controlling radiation exposures
from x-ray machines, other radiation-emitting equipment, and materials not licensed by the NRC.
The NRC issues regulatory guides to describe to the public methods that the staff considers
acceptable for use in implementing specific parts of the agency’s regulations, to explain techniques that
the staff uses in evaluating specific problems or postulated accidents, and to provide guidance to
applicants. Regulatory guides are not substitutes for regulations and compliance with them is not
This regulatory guide contains information collection requirements covered by 10 CFR Part 20,
“Standards for Protection against Radiation,” that the Office of Management and Budget (OMB)
approved under OMB control number 3150-0014. The NRC may neither conduct nor sponsor, and a
person is not required to respond to, any information collection request or requirement unless the
requesting document displays a currently valid OMB control number. The NRC has determined that this
regulatory guide is not a major rule as designated by the Congressional Review Act and verified this
determination with OMB.
Some organizations have recommended that exposures be kept ALARA. In its regulations and
guides, the NRC licensing staff has considered the basic radiation protection philosophy reflected in the
National Council on Radiation Protection and Measurements (NCRP), Report No. 107,
“Implementation of the Principle of As Low As Reasonably Achievable (ALARA) for Medical
and Dental Personnel,” 1990 (Ref. 5);
NCRP Report No. 116, “Limitation of Exposure to Ionizing Radiation,” 1993 (Ref. 6);
National Academy of Sciences, “The Effects on Populations of Exposure to Low Levels of
Ionizing Radiation: 1980” (Ref. 7);
Federal Radiation Council Report No. 5, “Background Material for the Development of Radiation
Protection Standards,” 1964 (Ref. 8);
International Commission on Radiation Protection (ICRP) Publication 60, “1990
Recommendations of the International Commission on Radiological Protection,” 1990 (Ref. 9);
ICRP Publication 103, “The 2007 Recommendations of the International Commission on
Radiological Protection,” 2007 (Ref. 10); and
American Conference of Governmental Industrial Hygienists, Committee on Industrial
Ventilation, “Industrial Ventilation: A Manual of Recommended Practice for Design,”
February 1, 2007 (Ref. 11).
The values proposed for maximum doses present a small risk when compared to the other hazards
of life. Nevertheless, in view of the incomplete evidence upon which the values are based, coupled with
the assumption that certain radiation effects are irreversible and cumulative, the NRC licensing staff
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strongly recommends that every effort be made to reduce exposure to all types of ionizing radiation to the
lowest reasonable level.
C. REGULATORY POSITION
The NRC will consider a licensee’s radiation protection program to be in compliance with the ALARA
requirements in 10 CFR Part 20 if the licensee has adopted and implemented the major principles and
practices identified below as part of its policies and programs.
Management Philosophy and Organization
The radiation protection responsibility of licensee management1 at a medical institution is to
maintain exposures ALARA for employees, visitors, students, and patients who do not receive
radiation or radioactive materials as part of their hospital care. The licensee should carry out this
responsibility with respect to employees and staff by the following means:
(1) information and policy statements2 to the medical and hospital staff;
(2) periodic management audit of operational efforts to maintain exposures ALARA;
(3) continuing management evaluation of radiation safety staffing, program, and budget
(4) management programs to ensure that all staff and employees who may be exposed to
radiation receive appropriate briefings and training in radiation safety, including ALARA
(5) delegation of sufficient authority to the Radiation Safety Officer (RSO) to enforce regulations
and administrative policies regarding radiation safety; and
(6) administrative direction to ensure that any new hospital facilities or equipment that may
affect radiation protection are planned or designed in consultation with the RSO.
Appendix M, “Model Procedures for an Occupational Dose Program,” to NUREG-1556,
Volume 9, presents a model program for implementing this management philosophy.
Radiation Safety Officer Functions
This guide uses the term “Radiation Safety Officer” (or RSO) to indicate the individual who
should be appointed, as provided in 10 CFR 35.24(b) (Ref. 12), to be responsible for implementing the
radiation protection program.
Staffing and Organizational Requirements
Appendix A to this guide presents a sample outline of the various tasks of a typical radiation
safety office. The time and effort required for each of the listed tasks vary widely depending on the size
of the medical institution and the nature and extent of radioactive material usage. Management should
(1) review the staffing requirements for each of these tasks and provide the necessary personnel to
establish and carry out radiation protection program requirements and (2) evaluate them annually.
Radiation Safety Personnel Qualifications
“Management” means the chief executive officer or other individual having the authority to manage, direct, or
administer the licensee’s activities, or those persons’ delegate or delegates.
Policy statements should include a detailed set of radiation exposure investigational levels, as presented in Appendix M
to NUREG-1556, Volume 9.
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Management should select an RSO who meets the requirements of 10 CFR 35.50, “Training for
Radiation Safety Officer,” and of 10 CFR 35.59, “Recentness of Training.” Management should carefully
review radiation protection personnel qualifications, based on the nature of the radiation safety program
and the extent of effort and expertise required to carry out the tasks noted in Appendix A to this guide.
Management should select radiation safety personnel appropriate to the radiation safety program
after careful review of the nature of the program and the extent of effort and expertise required to carry
out the tasks noted in the appendix.
Space and Equipment
The radiation safety office should have adequate equipment and space in appropriate locations to
allow the RSO to carry out the following functions:
(1) maintain, repair, and perform electronic calibrations on radiation safety equipment;
(2) calibrate radiation safety equipment with radioactive sources and check the calibrations of
other hospital sources (e.g., cobalt-60 if radiation safety and medical physics functions are
(3) stock radiation safety supplies for labeling, surveys, decontamination, and personnel
protection and monitoring;
(4) conduct radiometric measurement of smear tests from contamination surveys and source leak
(5) store radioactive waste and sources not in use;
(6) decontaminate personnel, clothing, and equipment;
(7) process orders for licensed radioactive materials and receive and distribute such materials;
(8) receive, process, and file regulations and licensing correspondence;
(9) prepare reports and records of surveys and personnel monitoring as required by
10 CFR Part 20; and
(10) instruct and brief personnel as required by 10 CFR Part 19, “Notices, Instructions and
Reports to Workers: Inspection and Investigations” (Ref. 13).
In addition, licensees should examine the tasks listed in the appendix to this guide for other
activities that may require specific space allocations for radiation safety offices in larger
Tasks and Procedures
The RSO and the radiation safety staff are responsible for conducting surveillance programs and
investigations to ensure that occupational exposures are ALARA. In addition, they should be vigilant in
seeking new and better ways to reduce doses for jobs involving radiation exposure. The appendix to this
guide, as well as NUREG-1556, Volume 9, provides a list of the types of tasks carried out by a radiation
safety office to ensure good radiation safety surveillance and to meet regulatory and license conditions.
For medical institutions that have a full or part-time professional health physics staff, this staff
should coordinate the planning of radiation safety procedures with management to ensure optimum
efficiency and exposures that are ALARA. This coordination should extend to the implementation of the
ongoing radiation protection program by the professional health physicists under the general supervision
of the RSO.
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The radiation safety office, supervised by the RSO, should carry out the radiation protection
program, including the tasks listed in the appendix to this guide. In accordance with 10 CFR 35.24(e), the
licensee shall establish the authority, duties, and responsibilities of the RSO in writing. The licensee’s
designation should include authority for the RSO to communicate directly with the level of management
that is able to take corrective action when needed to enforce rules and procedures pertaining to the
institution’s radiation protection program. The RSO should also be granted administrative authority to
suspend certain activities temporarily when necessary in emergencies to avoid immediate danger to life or
health. However, the RSO should exercise his or her authority to suspend activities only when their
suspension will not interfere with life-saving medical procedures that warrant an overriding priority and
that cannot await alleviation of the radiation safety problems.
Radiation Safety Committee
Licensees that are authorized for two or more different types of uses of byproduct material under
Subparts E, F, and H of 10 CFR Part 35, “Medical Use of Byproduct Material,” or two or more types of
units under Subpart H, shall, under 10 CFR 35.24(f), establish a radiation safety committee to oversee all
uses of byproduct material permitted by the license. As required by 10 CFR 35.24(f), the Committee
must include an authorized user of each type of use permitted by the license, the RSO, a representative of
the nursing service, and a representative of management who is neither an authorized user nor an RSO.
The Committee may include other members whom the licensee considers appropriate.
Facility and Equipment Design: General Considerations
The design of facilities and equipment required for the medical uses of radioactive materials
depends not only on hospital and medical care considerations but also on the nature and quantity of
radioactive materials involved and the relative potential for external and internal radiation exposure.
Regulatory Positions 10–21 below discuss the major aspects of planning and design that the licensee
The licensee should plan the facility layout to maintain employee exposures ALARA, while at the
same time ensuring that actions taken to achieve this objective do not increase exposure to other persons
in restricted or unrestricted areas. Considerations should include the following:
the need for access to radiation or radioactive material areas by medical staff, employees,
patients, visitors, and others, while providing optimum separation between work areas with
frequent occupancy and radiation sources or contamination;
ventilation requirements, including whether to maintain lower pressures in rooms in which
radioactive gases may possibly be spilled or volatilized;
floor loading for heavily shielded sources;
receipt and shipment of radioactive material, including radiation surveys of the shipping
ingress and egress of some radiation therapy and nuclear medicine outpatients, including parking;
the need to protect supplies of stored diagnostic films from radiation exposure.
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Permanent shielding may be needed in some cases for walls, floors, and ceilings to protect against
radiation associated with radioactive materials currently housed in the institution, as well as radioactive
materials that might be introduced into the area by future medical care requirements. Regulatory
Position 19 of this guide discusses permanent shielding for radiation therapy facilities. In shielding
calculations for a radiation therapy facility, the licensee should consider occupancy and use factors, as
recommended in NCRP handbooks, but such factors should be chosen with the principle of ALARA in
mind. The licensee should consult the NRC licensing staff during the planning and design stage to obtain
guidance on acceptable use and occupancy factors in shielding design.
Caution Signs and Interlocks
The licensee should use caution signs, alarm, electronic surveillance, and locks, as required by
10 CFR Part 20 and 10 CFR Part 35, to control or restrict access to certain areas.
To the extent possible, the licensee should take the following actions:
Provide any necessary local exhaust ventilation (such as chemical hoods) or general ventilation,
as recommended by professional health physicists, for areas where breathable concentrations of
radioactive material may be present.
Locate exhaust vents so as to provide meteorological diffusion and dilution adequate to meet
10 CFR Part 20 requirements for effluents to unrestricted areas and ALARA exposure
considerations for the public, as well as to avoid recirculating contaminated exhaust air into the
Where appropriate, include specific types of filters or air cleaners for the exhaust air.
Maintain rooms in which radioactive gases may be released at negative pressure with respect to
adjacent rooms by appropriate exhaust ventilation.
Licensees should consider the need for personnel to exit and close the facility to prevent the
spread of radioactive material for areas in which laboratory procedures could result in dispersal of
radioactive material in the event of a fire. Licensees should provide local showers and fire extinguishers,
where necessary. For the vast majority of medical institutions, emergency procedures and training should
include immediate fire control as a priority item.
Special Laboratory Design Features
Licensees should consider providing laboratory surfaces that may be easily cleaned and
decontaminated daily to maintain minimal contamination levels and radiation exposures, as well
as minimal interference with medical and clinical procedures. Laboratory needs may also include
(1) provision for appropriate placement of radiation- and contamination-monitoring instruments,
(2) designated sinks for rinsing and disposing of minor quantities of radioactive wastes (within
10 CFR Part 20 limits),
(3) special plumbing and waste storage provisions, and
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(4) adequate separation between areas occupied by personnel and radiation sources or
In general, no hospital procedure should use quantities of radioactive material that, because of
their radiotoxicity, could result in potential air concentrations approaching the concentration
values given in 10 CFR Part 20. Licensees should design ventilation and contamination control
to maintain air concentrations and contamination levels ALARA.
Storage, Source Control, and Inventory
In institutions ordering a number and variety of radioactive material sources, it is often easier,
less costly, and more secure to provide a centralized storage room for radioactive materials not in use or
used only occasionally. Such a facility is also helpful in keeping exposures ALARA, since it may result
in a decrease in the amount of radioactive material stored in laboratories occupied by personnel.
Shipping and Receiving
Medical institutions should take the following actions:
Plan specific radioactive material storage areas for day, night, and weekend deliveries, so that
deliveries of radioactive materials may be received at any time and placed in a secure locked
location where they may not cause unnecessary exposure to personnel while awaiting survey by
the radiation safety staff or the user. The licensee should ensure that a written procedure for
receipt, survey, and storage of deliveries is provided to anyone responsible for the receipt or
delivery of radioactive material.
Handle packages in such a way as to maintain exposures ALARA. For example, when packages
may expose couriers to measurable radiation, provide a cart or carrier that maintains an adequate
distance between the person transporting the material and the package to keep exposures
Locate shipping and receiving areas and access to them near areas where radioactive materials are
used to (1) minimize the time required for transporting radioactive material to areas where it is to
be used and (2) avoid the need to transport radioactive materials through crowded areas or areas
occupied by personnel, patients, or visitors.
Licensees should employ the following general features when using equipment to handle or
contain radioactive materials:
Surfaces should be easy to clean and decontaminate, in case unsealed radioactive material is
Equipment should be designed to optimize the ease of carrying out procedures where personnel
are exposed to radiation, thereby minimizing working times, and to maximize distances of
personnel from the radioactive materials with which they are working, to an extent consistent
with the purposes of the procedure.
Equipment should operate in such a fashion that it would not damage radiation sources and
release radioactive materials if it were to fail.
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Adequate shielding should be provided as part of the equipment, where feasible, to keep
Appropriate caution signs, symbols, signals, and alarms should be provided as part of the
equipment to meet the requirements of 10 CFR Part 20 and recommended standards of the
medical physics profession.
Radiation Therapy Equipment and Facilities
The NRC licensing staff provides specific licensing guides for licensed radiation therapy
programs and reviews the safety aspects of facilities and equipment before issuing a license. In designing
shielding for radiotherapy treatment rooms (e.g., teletherapy and gamma stereotactic radiosurgery units,
high-dose-rate brachytherapy, and gamma knife), the medical institution should consult NCRP
Report No. 151, “Structural Shielding Design and Evaluation for Megavoltage X- and Gamma-Ray
Radiotherapy Facilities,” issued in 2005 (Ref. 14), for recommended design details; specifications;
methods of shielding against direct, scattered, and leakage radiation; and general principles of radiation
In addition, the institution should protect each radiotherapy treatment room from inadvertent
entry by the following means:
(1) Provide a door interlock that allows a “Beam On” condition only when the door is closed and
turns the beam off if the door is opened.
(2) Provide independent backup caution lights on the console, above the door, and inside the
treatment room to indicate the “Beam On” condition to radiotherapy technologists and other
staff members. Independent audible signals provide added safety if the caution lights fail.
(3) Establish a procedure for determining whether everyone except the patient is out of the
treatment room before the door is closed and the beam is turned on.
(4) Install independent gamma-ray-sensing caution lights or signals near the entry inside the
treatment rooms to warn the radiotherapy technologist or others entering the room in case the
door interlock system fails when the beam is in the “on” condition.
(5) Provide a scram button for emergency shutdown of the source from inside the room and
provide audio communication into the room from the outside control panel.
The institution should consider leakage through the radiotherapy unit with the source in the “on”
position when designing shielding. Data provided by the manufacturer of the radiotherapy unit
and NCRP recommendations can be used for this purpose.
The institution should design areas adjacent to the treatment room that will be occupied by
personnel, patients, or visitors who are not associated with the radiation therapy department so
that exposures to these areas are maintained ALARA. Reduction of occupational exposures to
radiation therapy personnel should be achieved by design provisions, procedures, or beam
orientations that are directed toward unoccupied or low-occupancy areas. The design should
ensure that dose rates will not exceed 0.002 rem (0.02 millisievert) in 1 hour and 0.05 rem
Rev. 2 of RG 8.18, Page 8
(0.5 millisievert) in a year (see 10 CFR 20.1301, “Dose Limits for Individual Members of the
Public”) in restricted or unrestricted areas adjacent to the radiotherapy treatment rooms.
Nuclear Medicine Facilities
To ensure that exposures are ALARA, the layout and design for new nuclear medicine facilities
and equipment should accomplish the following:
Allow sufficient space for personnel operating nuclear medicine equipment to be at least 1 meter,
and preferably 2 meters, from any patient undergoing imaging, whenever the condition of the
patient and other conditions permit, or provide adequate portable shields.
Allow adequate space for stretcher patients awaiting scans, as well as for outpatients. Dosed
patients awaiting scans may generate radiation levels on the order of 0.010 rem (0.10 millisievert)
or more near the edge of the stretcher. These patients may need to be segregated from the general
waiting area to reduce radiation exposure to receptionists and persons passing through the area,
such as technologists and aides.
Locate physicians’ offices and other occupied areas within easy access to needed
radiopharmaceuticals, but allow enough distance (several meters is usually sufficient) to
minimize exposures from stored radiopharmaceuticals and radioactive wastes.
Provide adequate shielding for stored radiopharmaceuticals and adequate body shielding for
employees preparing dosages for patients.
Supply an adequate number of syringe shields and vial shields (as well as appropriate tongs or
forceps) near the place of dosage preparation.
Provide adequate exhaust ventilation (see Ref. 11) in the laboratory near or in the
radiopharmaceutical storage and dose preparation areas to protect against airborne radioactive or
toxic materials that might result from accidental release or spill of radiopharmaceuticals.
Include a special shielded waste receptacle for used syringes and other radioactive wastes in the
nuclear medicine laboratory near the dosage preparation area.
Locate a permanently fixed radiation counter or rate meter near the entrance to the nuclear
medicine preparation laboratory for employees to check regularly for hand or clothing
contamination when leaving the department. A portable survey meter available at a convenient
location should also help keep exposures ALARA.
Provide individual labeled lockers and change areas for segregating laboratory coats that may be
contaminated from other clothing when operations are such that contamination levels on persons
or clothing may exceed the action levels of Regulatory Guide 8.23, “Radiation Safety Surveys at
Medical Institutions” (Ref. 15).
Provide finger badges or dosimeters, as well as body dosimeters, to monitor the occupational
exposure of personnel involved in dose preparation and the injection and handling of patients.
In Vitro Clinical and Research Laboratories
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Many of the design considerations for in vitro clinical and research laboratories are similar to
those already stated for other facilities. Special considerations include the following:
easily discarded bench paper, absorbent on the top surface only, for catching and easily disposing
of small amounts of contamination that may drip or be removed from laboratory apparatus and
suitable, easily cleaned drip trays for manipulating radioactive materials where spillage may
protective clothing, including disposable gloves (which should be changed frequently), for
persons working with radioactive materials.
In addition, the licensee should provide equipment for monitoring clothing before laundering.
Radioactive laundry and radioactive wastes should be turned over to the radiation safety office for further
disposition when surveys indicate contamination levels that may exceed 5000 dpm per 100 square
NCRP Report No. 105, “Radiation Protection for Medical and Allied Health Personnel,” issued in
1989 (Ref. 16), provides additional information on carrying out in vivo experiments with animals.
Safe Work Practices and Procedures: General Principles
The NRC staff recommends, as a minimum, the safe work practices and procedures contained in
this section for handling radioactive materials in medical institutions. Regulatory Guide 8.23 and
NUREG-1556, Volume 9, contain additional information.
Periodic Inventory and Control of All Radiation Sources
Many of the more serious occupational exposures, as well as patient exposures, have resulted
from misplaced or lost radioactive material, which may inadvertently expose unsuspecting persons or may
be subject to improper use by unauthorized persons. Licensees should use the following procedures to
guard against these problems:
According to 10 CFR 35.67(g), a licensee in possession of sealed sources or brachytherapy
sources, except for gamma stereotactic radiosurgery sources, shall conduct a semiannual physical
inventory of all such sources in its possession. The licensee shall retain each inventory record in
accordance with 10 CFR 35.2067(b). The inventory should be combined with an inspection to
ensure proper labeling (see 10 CFR 35.69, “Labeling of Vials and Syringes,” and
10 CFR 20.1902, “Posting Requirements”).
Sources should be secured within locked rooms or storage areas when authorized users or their
responsible employees are not present (see Regulatory Position 16 of this guide). Licensees
should provide special shielded vaults or containers in the storage area for sealed sources.
Authorized persons should be required to sign for the removal and return of each source. The
radiation safety office staff should regularly check the source log.
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All radioactive material not in use should be shielded so that exposure rates in any area that may
be occupied by personnel should be well below (i.e., ALARA) the levels for unrestricted areas given in
10 CFR Part 20. Whenever radioactive materials are in use, the material should be unshielded only in the
direction necessary for its use and to the extent that accessibility to the source is necessary.
Control of Contamination
Licensees should ensure that radioactive materials in unsealed form or undergoing chemical or
physical processing should be handled only in properly designed facilities (as described in Regulatory
Position 20 of this guide) and with proper procedures to avoid transferring radioactive material to the air
or to surfaces if inhalation or ingestion of the material by personnel is possible. Heat sterilization should
be avoided if it might rupture the source. If necessary to ensure that exposures are ALARA, licensees
should conduct preliminary tests of procedures with nonradioactive simulated materials or colored liquids
to check provisions for containment, handling, and ventilation. The radiation safety office staff may
make preliminary estimates of job exposure commitments using tracer levels of radioactive material.
Trays and absorbent materials should be used as a backup to catch and limit the spread of
radioactive contamination whenever a possibility exists that planned procedures may fail to contain the
Personnel should wear protective clothing appropriate to the type and quantity of the radioactive
material being processed whenever escape of radioactive contamination is considered possible.
Proper Work Habits
In general, licensees should train all personnel handling radioactive materials to use appropriate
shielding materials, maintain as much distance as possible from radiation sources, and limit the
time of exposure to radiation sources to the time necessary to carry out the required task or
The following good work habits are particularly important in ensuring that exposures are
(1) Except for very low level sources, such as flood sources or other sources designed for manual
use in checking instrumentation, sealed or unsealed sources should not be touched or held with
the fingers, but only with tongs or tweezers appropriate to the operation.
(2) Personnel who are handling or manipulating unsealed or unshielded sources with tongs or
forceps or who are holding partially shielded containers of radioactive material with their
hands should wear finger dosimeters,3 as well as body dosimeters. However, these
dosimeters are not needed for personnel handling only the types of sources used for tracerlevel in vitro studies or if dose rates are less than 5 millirem (0.05 millisievert) per hour at
(3) Special attention should be given to instructing all nursing staff and others coming in contact
with a patient who may be excreting radioactive material that they may need to follow
precautions to avoid contaminating themselves and others.
With some finger dosimeters, labels may wash off or the badge may rip protective gloves. In these cases, wrist badges
may be preferable. In any case, the user should be aware that neither of these dosimeters will measure very high
finger-contact doses, and handling unshielded syringes or bottles with the fingers should absolutely be avoided.
Rev. 2 of RG 8.18, Page 11
(4) When working with unencapsulated radioactive materials, personnel should wear disposable
gloves and other special clothing.
(5) Care should be taken to avoid needless contamination of objects such as light switches, taps,
or door knobs.
(6) Radioactive solutions should never be pipetted by mouth.
(7) Eating, smoking, drinking, and application of cosmetics should be prohibited in laboratories
where radioactive materials are handled.
(8) Special precautions should be taken to avoid the possibility of small amounts of radioactive
material entering cuts.
(9) The use of containers or glassware with sharp edges should be avoided. Care should be taken
to avoid bites or scratches when working with animals to which radioactive materials have
(10) Food and drink should not be stored in the same place (e.g., the refrigerator) with radioactive
(11) Radioactive materials should be secured (e.g., placed in a locked room) when personnel are
(12) Surveillance of individual operations, such as “milking” generators, should be provided to
ensure that workloads are distributed so that individual employee doses are kept ALARA.
(13) Hand lotion may be used after removing disposable gloves and washing hands.
(14) Training and education on good practice (e.g., procedure planning, repeating procedures
using nonradioactive sources) should be provided to the workers.
(15) All tools increasing the distance (e.g., forceps) between the hand/finger and the source are
very effective for dose reduction.
(16) Use of shields or increasing the distance is more effective than accelerating the work speed.
Radiation or Radioactivity Monitoring
Section C.2 of this guide discusses the independent radiation surveys, inspections, inventories,
and smear tests to be carried out by the radiation safety office staff. In addition, each user of radioactive
materials should survey radiation and radioactivity levels at the end of each day of use (10 CFR 35.70(a))
within his or her own operations to help maintain exposures ALARA. A simple logbook of readings or
general levels of radiation or contamination maintained by the user may help to indicate any changes in
radiation or radioactivity levels that show a need to modify procedures or equipment to meet ALARA
radiation exposure objectives. Regulatory Guide 8.23 and NUREG-1556, Volume 9, offer further
guidance on radiation surveys in medical institutions and nuclear pharmacies.
In hospital situations in which higher exposure rates may occur (e.g., in teletherapy rooms where,
in an accident, the limits of 10 CFR Part 20 could be approached before an indication is provided by
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routine personnel monitoring devices), self-reading devices that the wearer may read at least daily, as well
as warning devices worn on the body, may help to maintain exposures ALARA.
Licensees should make employees aware of the ALARA provisions of 10 CFR Part 20 and the
guidance of Regulatory Guide 8.10. Employees should be instructed in the philosophy and
recommendations of Regulatory Guide 8.13, “Instruction Concerning Prenatal Radiation Exposure”
(Ref. 17), whenever there is a possibility that pregnant women may be exposed to radiation.
Employees should be acquainted with their individual institution’s own procedures for handling
radioactive sources and radioactive materials and with NRC licenses and their radiation safety provisions
(including license conditions incorporated from license applications and correspondence). Licensees
should make available copies of these procedures, licenses, and related correspondence for review by
employees as part of their orientation to radiation safety requirements. Licensees should also support
professional education and development to ensure that staff members are up to date on radiation safety
Licensees should consult this regulatory guide and NUREG-1556, Volume 9, for topics important
in training radiation workers.
This guide provides recommendations for maintaining exposures ALARA in three subdivisions
of radiation therapy:
Radiotherapy—the treatment of patients with high-energy beams from shielded equipment
containing sources of high gamma-ray emission rates
Brachytherapy—the treatment of patients by insertion of sealed sources such as needles or tubes
for interstitial or intracavitary irradiation or by surface application
Radiopharmaceutical therapy—the injection or oral administration of solutions or radioactive
pharmaceuticals that tend to concentrate in and irradiate the organs in which they are dispersed or
Radiation protection measures in radiotherapy should rely primarily on the adequacy of facilities
and equipment, since very intense radiation levels are generated. Nevertheless, the licensee
should use the following basic and routine operating principles for maintaining occupational
With the aid of the maintenance and operating manuals provided by the manufacturer of the
radiotherapy unit, procedures for routine maintenance and checking of safety-related features of
the teletherapy unit should be established.
A daily morning checkout procedure should be established and posted for the therapy
technologist to carry out simple operational checks of indicator lights, caution lights and signs,
key and door interlocks, gamma radiation-level indicators, timer operation, and interlock
Rev. 2 of RG 8.18, Page 13
A general safety check, including a spot or point radiation output check and a check on beam
alignment and confining devices, should be made and recorded at least monthly. All records of
the monthly output and safety check, as well as the morning checkouts, should be signed and
dated by the persons carrying out the tests.
During patient treatment or operation of the radiotherapy unit for calibration or maintenance
procedures, care should be taken to follow written instructions and to use installed safety devices
to ensure that no personnel except the patient to be exposed are in the treatment room during the
“Beam On” condition. These procedures are also important when personnel carry out test
procedures with phantoms on the treatment table.
During “Beam On” operation, the operator at the console should remain in a position of lowest
radiation intensity, while maintaining vigilance of the console and the patient during treatment, as
advised by the radiation safety office staff using the post installation radiation survey. In a welldesigned facility, the shielding provides a very high degree of protection at the location of the
console. However, all persons not required to remain near the console should remain or work in
areas of lower radiation intensity while the radiotherapy unit is in operation. During “Beam Off”
conditions, treatment setup should be accomplished with minimum occupancy of the room and
minimum time spent near the source to keep exposures from leakage radiation ALARA.
Emergency procedures established as required by NRC regulations or license conditions should
be tested by regular familiarization sessions or by staging mock emergencies for the training of
NCRP Report No. 40, “Protection Against Radiation from Brachytherapy Sources,” issued in
1972 (Ref. 18), provides detailed recommendations for reducing radiation exposures in brachytherapy,
and NCRP Report No. 155, “Management of Radionuclide Therapy Patients,” issued in 2006 (Ref. 19),
contains additional recommendations pertinent to brachytherapy, as well as to radiopharmaceutical
therapy. The licensee should also consider the following important practices for maintaining exposures
Afterloading devices should be used wherever medically acceptable. Remote afterloaders are
particularly effective in keeping exposures ALARA.
Jigs or remote afterloaders should be prepared and tested for ease in loading sources into
afterloading devices in the patient’s room.
When manual afterloading is used, jigs for loading the afterloaders should be set up behind
shields with lead-glass viewing windows, and auxiliary lead-brick shielding should be provided
to shield the arms of the personnel loading the afterloaders for as much of the duration of the
procedure as possible.
When the radiation sources of afterloading sleeves or ovoids are loaded, they should be placed in
adequately shielded carts or transport devices for liquid sterilization or transport to the patient’s
room when the physician is ready to insert the afterloaders. These carts should be properly
tagged and should, at all times, be under the supervision of the radiation physicist, the radiation
safety staff, or a member of the radiotherapy staff.
Rev. 2 of RG 8.18, Page 14
Similar protection should be provided for use in threading radioactive needles for implant
While manipulating sources, loading the afterloaders, and threading needles, personnel should be
provided with tongs and surgical clamps to maintain the distance of the fingers at least
30 centimeters from these sources.
Personnel should wear finger dosimeters, as well as body dosimeters, when they are loading or
preparing sources for insertion. Also, the radiation safety office staff should periodically survey
the loading procedures and provide job-time and exposure information to help employees
maintain exposures ALARA. Use of a gamma alarm monitor in the storage or loading area will
indicate when radiation sources are outside their shields and help to avoid inadvertent exposures
resulting from lost or misplaced sources (see 10 CFR 20.1101(b) and 10 CFR 20.1601, “Control
of Access to High Radiation Areas”).
A continuing list and count of removals and returns of individual sources from the storage
containers should be maintained to help ensure against inadvertent loss of sources and exposure
Sources maintained in fixed position for a constancy check on the operation of any intracavitary
ion chambers should be kept within shielded wells in constant geometry so they can be used for a
rapid and safe check of ion chamber operation before the treatment of each patient.
The radiation safety staff should carry out job-time/exposure studies on typical surgical implants
and typical insertions of radioactive sources—either in the operating room or by afterloading in
the patient’s room. These time/exposure studies should be recorded and reported to the personnel
involved to maintain an awareness of radiation exposures resulting from these procedures.
The radiation safety office staff or the radiation therapy staff should directly supervise the
transport of a patient containing radioactive material to areas outside the operating room and to
his or her room. Also, radiation safety office staff or radiation therapy staff should check and
supervise the transport of afterloading sources and supplies for the insertion of applicators, lead
bedside shields for the nurses, and any other supplies and equipment required for expediting an
efficient afterloading procedure. Radiation surveys should also be carried out on a sample basis
and recorded to maintain an awareness of the exposures resulting from these procedures.
Nursing personnel should be provided with personnel dosimeters (when required by
10 CFR Part 20) and should be trained in their use.
Radiation safety staff or radiation therapy staff should survey patients after removal of
brachytherapy sources and before discharge as a final step to check against incomplete removal of
these sources from the patient, leakage of contamination from sources, or inadvertent loss of
sources. All linens and waste should remain in the room until checked by a survey meter or until
all sources are accounted for.
Radiopharmaceutical Therapy (Nuclear Medicine Therapy with Unsealed Radioactive Materials)
Where feasible and in the best interests of the patient, licensees should ensure that administration
of the types of radioactive drugs used for therapy of specific diseases is carried out in a specific area or
room separate from other nuclear medicine or radiotherapy operations. However, this special area or
room should be in the general vicinity of the laboratory where the radiopharmaceuticals are stored to
Rev. 2 of RG 8.18, Page 15
eliminate the need to transport these materials over long distances or through other areas of the institution.
When these materials must be transported to a patient’s room for administration, good radiation safety
practice and efficient medical procedures often dictate that the radiation safety staff or nuclear medicine
therapy staff monitor and assist in the preparation of the materials and supplies, the transport of the
materials to the patient’s room, and the administration of the radioactive drugs, as directed by the
physician in charge. When therapy is carried out with potentially volatile radioiodine compounds,
licensees should consult Regulatory Guide 8.20, “Applications of Bioassay for I-125 and I-131”
(Ref. 20), to determine whether employees who have participated in the radioiodine administration should
be sampled for bioassay.
Licensees must follow the requirements in 10 CFR 35.75, “Release of individuals containing
unsealed byproduct material or implants containing byproduct material,” in authorizing the release from
control of any individual who has been administered unsealed byproduct material or implants containing
byproduct material. The patient release criteria used for the patient and the instructions given on ways to
minimize contamination of the environment and exposure to members of the public should be also in
accordance with Regulatory Guide 8.39, “Release of Patients Administered Radioactive Materials”
After treatment, all articles such as bedding, clothing, food, towels, and food trays should be
surveyed for possible contamination before they are released from the room. Contaminated articles must
be held for decay or disposal according to 10 CFR 35.92, “Decay-in-Storage.” The patient should be
surveyed before release and should be instructed on ways to minimize contamination of the environment
and exposure of other members of the public.
In supervising the administration of radiopharmaceuticals to patients, the physician in charge and
the radiation safety staff may use many of the principles given for brachytherapy in Regulatory
Position 31 of this guide, as well as principles and practices presented in NCRP Report No. 155. The use
of these procedures should help to ensure that exposures to hospital staff and private-duty nurses are
ALARA, not only during the administration of the dosage to the patient but also during any hospital care
of the patient, during and after discharge of the patient, and in the event of any later surgery, autopsy, or
burial of the patient. NUREG-1556, Volume 9, provides additional guidance.
Diagnostic Nuclear Medicine
Many of the principles of radiation protection practice in diagnostic nuclear medicine and general
principles of safe work practices in handling radioactive materials were discussed in previous sections on
recommendations for nuclear medicine facilities and equipment and general principles of safe work
practices in handling radioactive materials. Additional recommendations include the following:
Use syringe shields for administering all injections of radioactive material; only compromise this
procedure on rare occasions when absolutely necessary. Use disposable gloves to protect against
possible hand contamination.
Place radionuclide generators in a remote, well-shielded enclosure to reduce external exposure to
Use samples in shielded bottles for checking the assay of eluates in the nuclear medicine dose
calibrator or other suitable assay system. Calibration procedures with a smaller quantity of
radioactive material may sometimes reduce exposures to the staff.
Rev. 2 of RG 8.18, Page 16
Shield chamber calibrators, where possible, to maintain employee exposures ALARA and reduce
background radiation while nuclear medicine doses are being calibrated. Recalibrate refitted
chambers as necessary.
Use fume hoods (see Ref. 11) and good contamination control principles in situations that involve
potential airborne radioactive materials.
Consistent with ease of disposal, keep shielded radioactive waste cans for used syringes and other
radioactive wastes at the greatest distance from those areas in the laboratory most frequently
occupied by personnel.
Use protective lead screens to shield employees and other patients during procedures using
technetium-99m (Tc-99m) or other gamma emitters if the screens do not interfere with the
diagnostic tests. Portable screens of lead only 2 millimeters thick will reduce Tc-99m gamma-ray
exposure rates to less than 1 percent of those without the screens.
In lung perfusion or ventilation studies with xenon-133 (Xe-133), use additional lead shielding
1.6 millimeters thick (or appropriate thicknesses for other radioactive gases or aerosols) around
the absorber canister, oxygen bag, and waste receptacle to reduce occupational exposures when
undertaking frequent procedures. Use proper equipment to prevent leakage or contamination
from the radioactive material being used. Installation of a Xe-133 monitor in the room where
ventilation studies are performed should warn of any leakage of Xe-133.
In addition to regular nursing staff members who receive personnel monitoring, private-duty
nurses and others who may come in close contact with patients who have been administered
radiopharmaceuticals for diagnostic or therapeutic purposes should receive appropriate
instructions and briefings on radiation protection procedures.
Low-Level Clinical or Medical Research Laboratory Activities
Laboratories in medical institutions that use tracer amounts of the less radiotoxic nuclides may
keep exposures ALARA by using the recommendations contained in regulatory positions previously
described in this guide. Many of the radionuclides used for in vitro clinical tests, such as
radioimmunoassay, and other low-level in vitro or animal studies involve pure beta emitters or weak
gamma emitters, with individual personnel handling and processing only microcurie or submicrocurie
quantities at any one time. External and internal radiation exposures to personnel in such laboratories
should ordinarily be maintained well below 10 percent of the permissible occupational exposure limits of
10 CFR Part 20 through careful initial planning of laboratory facilities, equipment, and procedures by the
laboratory supervisor, in conjunction with qualified health physics personnel.
Management Audit and Inspection of the Radiation Protection Program
The governing body of the hospital bears the ultimate responsibility for the establishment and
continuation of an adequate radiation protection program in a medical institution. The administrator
reporting to this governing body should be sufficiently informed at all times to ensure that all regulations
are faithfully adhered to and that radioisotopes are properly used and safely handled to maintain
The hospital administration should perform an annual audit of the radiation protection program in
cooperation with members of the radiation safety committee and the radiation safety office. The results
of this audit may then be discussed at a radiation safety committee meeting to ensure that all users and
Rev. 2 of RG 8.18, Page 17
responsible staff are aware of current policies and procedures and methods for their improvement.
NUREG-1556, Volume 9, contains a sample checklist of items that may be inspected by the
administration during this annual audit. The radiation safety office should maintain a report of the results
of the audit for possible use in expediting any inspections by regulatory or accrediting agencies, as well as
for reference in further audits and for improving the ALARA program.
The purpose of this section is to provide information to applicants and licensees regarding the
NRC’s plans for using this regulatory guide. The NRC does not intend or approve any imposition or
backfit in connection with its issuance.
In some cases, applicants or licensees may propose an alternative method for complying with
specified portions of the NRC’s regulations. Otherwise, the methods described in this guide will be used
in evaluating compliance with the applicable regulations for license applications, license amendment
applications, and amendment requests.
Rev. 2 of RG 8.18, Page 18
10 CFR Part 20, “Standards for Protection against Radiation,” U.S. Nuclear Regulatory
Commission, Washington, DC.
Regulatory Guide 8.10, “Operating Philosophy for Maintaining Occupational Radiation
Exposures as Low as Is Reasonably Achievable,” U.S. Nuclear Regulatory Commission,
NUREG-1556, Volume 9, Revision 2, “Consolidated Guidance about Materials Licenses:
Program-Specific Guidance about Medical Use Licenses,” U.S. Nuclear Regulatory Commission,
Washington, DC, January 2008.
Regulatory Guide 8.37, “ALARA for Effluents from Materials Facilities,” U.S. Nuclear
Regulatory Commission, Washington, DC.
NCRP Report No. 107, “Implementation of the Principle of As Low As Reasonably Achievable
(ALARA) for Medical and Dental Personnel,” National Council on Radiation Protection and
Measurements, Bethesda, MD, 1990.5
NCRP Report No. 116, “Limitation of Exposure to Ionizing Radiation,” National Council on
Radiation Protection and Measurements, Bethesda, MD, 1993.
“The Effects on Populations of Exposure to Low Levels of Ionizing Radiation: 1980,” National
Academy of Sciences—National Research Council, Washington, DC, 1980.6
Report No. 5, “Background Material for the Development of Radiation Protection Standards,”
Federal Radiation Council, Washington, DC, 1964.7
ICRP Publication 60, “1990 Recommendations of the International Commission on Radiological
Protection,” Pergamon Press, Oxford, 1990.
ICRP Publication 103, “The 2007 Recommendations of the International Commission on
Radiological Protection,” Pergamon Press, Oxford, 2007.
Publicly available NRC published documents listed herein are available electronically through the Electronic Reading
room on the NRC’s public Web site at: http://www.nrc.gov/reading-rm/doc-collections/. The documents can also be
viewed on-line or printed for a fee in the NRC’s Public Document Room (PDR) at 11555 Rockville Pike, Rockville,
MD; the mailing address is USNRC PDR, Washington, DC 20555; telephone (301) 415-4737 or (800) 397-4209; fax
(301) 415-3548; and e-mail [email protected]
Copies may be purchased from the National Council on Radiation Protection and Measurements (NCRP), 7910
Woodmont Avenue, Suite 400, Bethesda, MD 20814-3095 (telephone: (301) 657-2652). Purchase information is
available through the NCRP Web site at http://www.ncrppublications.org/Reports/.
Copies of National Academy of Science reports may be found at The National Academies Web site at
Copies of Federal Radiation Council reports may be found at the U.S. Environmental Protection Agency Web site at
“Industrial Ventilation: A Manual of Recommended Practice for Design,” American Conference
of Governmental Industrial Hygienists, Committee on Industrial Ventilation, Cincinnati, OH,
February 1, 2007.8
10 CFR Part 35, “Medical Use of Byproduct Material,” U.S. Nuclear Regulatory Commission,
10 CFR Part 19, “Notices, Instructions and Reports to Workers: Inspection and Investigations,”
U.S. Nuclear Regulatory Commission, Washington, DC.
NCRP Report No. 151, “Structural Shielding Design and Evaluation for Megavoltage X- and
Gamma-Ray Radiotherapy Facilities,” National Council on Radiation Protection and
Measurements, Bethesda, MD, 2005.
Regulatory Guide 8.23, “Radiation Safety Surveys at Medical Institutions,” U.S. Nuclear
Regulatory Commission, Washington, DC.
NCRP Report No. 105, “Radiation Protection for Medical and Allied Health Personnel,” National
Council on Radiation Protection and Measurements, Bethesda, MD, 1989.
Regulatory Guide 8.13, “Instruction Concerning Prenatal Radiation Exposure,” U.S. Nuclear
Regulatory Commission, Washington, DC.
NCRP Report No. 40, “Protection Against Radiation from Brachytherapy Sources,” National
Council on Radiation Protection and Measurements, Bethesda, MD, 1972.
NCRP Report No. 155, “Management of Radionuclide Therapy Patients,” National Council on
Radiation Protection and Measurements, Bethesda, MD, 2006.
Regulatory Guide 8.20, “Applications of Bioassay for I-125 and I-131,” U.S. Nuclear Regulatory
Commission, Washington, DC.
Regulatory Guide 8.39, “Release of Patients Administered Radioactive Materials,” U.S. Nuclear
Regulatory Commission, Washington, DC.
Copies may be purchase from the American Conference of Governmental Industrial Hygienist website at
RADIATION SAFETY TASKS INVOLVED IN KEEPING
OCCUPATIONAL EXPOSURES AS LOW AS IS REASONABLY
Surveys of Radioactivity Areas
radioactive waste disposal and storage
other research and clinical laboratories using radioactive materials
Survey of Diagnostic and Therapeutic Machines and Generators
teletherapy sources and machines
positron emission tomography cameras
review of personnel exposure data and reports
review of reports required by regulations
filing, collecting, and mailing personnel monitoring devices (including late and lost)
special investigations of exposure and notifications to regulatory agencies where appropriate
calibration of personnel monitoring dosimeters, including commercially supplied film badge
Radiation Safety Instrument Calibration and Maintenance
Licensees should ensure that radiation safety instruments are properly calibrated and maintained
using the following methods:
battery replacement and adjustment
pocket chamber and thermoluminescence dosimeter calibration
minor repair (electronic)
instrument selection and distribution
Decontamination and Waste Disposal Practices
collection and packaging
decontamination of surgical instruments, rooms, and laboratories
Techniques for Leak-Testing of Radioactive Sources
Means of Evaluating Internal Exposure
collection of samples, including air samples, where applicable
radiochemical or scintillation bioassay analysis
in vivo counting
computer analysis of results
Special Surveys of Patients and Rooms for Implant, Intracavitary, or Unsealed
room preparation and protective covering
labeling (bed, chart, door)
nursing staff and housekeeping staff briefings
source insertion and afterloading surveys
surveys of patients in operating and recovery rooms
placing of lead barriers
recovery of sources and wastes surveys of room cleanup and decontamination instructions to
patient and to family of patient, as appropriate
measurement of radiation from cadavers and briefings to pathology staff and funeral directors,
Administration and Consultation
approval of facilities, equipment, and procedures used in areas where radioactive materials are
preparation of license applications and amendments
preparation of hazard evaluation reports for licensing
programming of routine required surveys
supervision of routine radiation safety operations
revisions to radiation safety manual
periodic radiation safety instruction for hospital staff and administration
training of residents and medical staff
conferences with physicians and other safety staff
coordination of radiation safety committee meetings and minutes
inspections and discussions with Government regulatory agency representatives
selection and ordering of equipment and supplies
planning and budgeting
facility and shield design and meetings with architects
records maintenance and related computer programming
planning for prompt, effective response to incidents and emergencies involving radiation
provision of instruction or direction for outside persons (e.g., firefighters) who would
respond to an emergency situation involving or potentially involving radiation
preparation of radiation safety office reports to hospital administration