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Muhammad Naveed SaeedSenior Cath. Lab. Technician

National Institute of Cardio Vascular Disease

Karachi. Pakistan

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What does the word "ALARA" stand for?

an acronym for

oA As

oL Low

oA As

oR Reasonably

oA Achievable

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Sample Question and AnswerSample Question and Answer

The following slides are example questions using thelayouts in the Quiz Show template. View them in slideshow to see the answer animations.

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ow is ALARA used in the practice ofow is ALARA used in the practice ofadiation protection?adiation protection?

ALARA is a basic radiation protection concept orphilosophy. It is an application of the "Linear NoThreshold Hypothesis," which assumes that there is no"safe" dose of radiation. Under this assumption, theprobability for harmful biological effects increases withincreased radiation dose, no matter how small.Therefore, it is important to keep radiation doses toaffected populations (for example, radiation workers,minors, visitors, students, members of the generalpublic, etc.) as low as is reasonably achievable.

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Is the "no safe dose" assumption valid?Is the "no safe dose" assumption valid?

This assumption is currently being hotly debated in thescientific community. Although the "jury is still out" onthis issue, it appears that there is more evidence thannot that there is, indeed, a safe dose level. It isconceivable that if our knowledge of radiation effectsexpands to the point that a "safe" dose is defined, theALARA philosophy, as we know it today, would beeliminated.

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Why should I be interested in the ALARAWhy should I be interested in the ALARAphilosophy?philosophy?

Even if you are not a radiation worker or have ever visited

a nuclear facility, you should be aware that thephilosophy to keep radiation exposures as low asreasonably achievable is an integral component ofradiation protection programs throughout this countryand the world. While one of its primary aims is to reducethe dose incurred by an occupational worker, another

equally important ALARA goal is to minimizeradiation/radioactivity releases to the environment -your environment! When ALARA goals are realized at thenuclear facility in your "neighborhood", everyonebenefits.

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How did this philosophy develop and become aHow did this philosophy develop and become arequired component of radiation safety or healthrequired component of radiation safety or healthphysics programs?physics programs?

Reducing radiation exposures to levels that are "as low as

reasonably achievable" has long been a goal of radiationsafety programs. The concern over possible geneticeffects (effects that can be passed from adults to theirchildren) in the 1960s led the Atomic Energy Commission(AEC), the predecessor to the Nuclear Regulatory

Commission (NRC) and the Department of Energy (DOE),- two federal regulatory authorities in the United States- to require that human exposures be kept "as low aspracticable" (the "ALAP" philosophy). Although ALARA wasrecognized during this time frame, emphasis was placedon controlling exposures in the workplace within thedose limits, rather than lowering the exposures to levels

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Then what happened?Then what happened?

Emphasis on the ALARA philosophy heightened in the 1970s

when scientists studying Japanese survivors of theatomic bomb blasts noticed an increased incidence ofsolid tumors (i.e., tumors other than leukemia). Similarincreases were also observed in patients undergoingmedical treatments. These increases were associated

with very large radiation doses. Unfortunately, thescientists were not able to say whether the same resultsoccur at small doses.

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Can you explain further?Can you explain further?

An analogy that might help to explain this problem deals

with exposure to the Sun. We all know that prolongedexposure to intense sunlight will cause not only sunburnsbut also increase the likelihood of contracting skindiseases (e.g., cancer) in the future. Scientists can't saywhether less intense exposure will also cause long-term

skin problems. Therefore, they recommend using sunscreen and avoiding exposure to intense sunlight, evenfor brief periods.

Continue

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In a similar manner, the observations of increased cancer

led the International Commission on Radiological Protection(ICRP), a body of recognized radiation experts which offerrecommendations to regulatory agencies around the world,to state that, "As any exposure may involve some degree ofrisk, the Commission recommends that all unnecessaryexposures be avoided, and that all justifiable exposures bekept as low as is reasonably achievable, economic, andsocial considerations being taken into account." Because ofthis and other findings, both the DOE and NRC, for anumber of years, have required an ALARA program atnuclear facilities.

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Why does the ALARA concept include social,Why does the ALARA concept include social,technical, and economic considerations?technical, and economic considerations?

If we had an infinite amount of money, we could think of

all sorts of techniques to reduce radiation dose. Some ofthese techniques may not be technically feasible (e.g.,snuffing out the Sun, since it releases so muchradiation). Some techniques would be so expensive that,even though they might be technically feasible, they

couldn't be justified (e.g., requiring that every home beequipped with a radon interception system withoutconsidering whether radon was a problem or not). Sometechniques simply wouldn't be acceptable to society(e.g., forbidding homes to be built in Denver since itsbackground is higher than areas with lower elevations).

Continue

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Most scientists and all standard-setting bodies feel that the

radiation limits currently in force are safe. They feel that itis prudent, however, to reduce radiation doses below theselimits when it makes sense. This concept is captured in theALARA philosophy by incorporating the word "reasonable"into its definition. Of course, we must determine whatconstitutes a "reasonable" approach. Certainly, this couldwell be subject to widely different interpretations!

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What kind of interpretations?What kind of interpretations?

For example, suppose your entire community supported

the construction of a lead-lined dome over your homesto reduce the natural background dose received fromcosmic radiation each and every day. While this iscertainly possible from a technical standpoint (i.e., sucha dome could conceivably be built), and from a social

perspective (since it has been found to be acceptable tothe community), is it nonetheless "reasonable" to build itif the cost for such a dome is several billion dollars?Probably not, in this instance, since it would afford verylittle reduction in the natural background radiationdose . . . certainly nothing observable. Therefore,several factors are, by design, involved in the

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Is the ALARA concept affiliated with a particularIs the ALARA concept affiliated with a particulardose limit.?dose limit.?

No. ALARA is not a dose limit, but rather a goal. It

exemplifies a mind set to achieve radiation exposureswhich are as far below the applicable limits as isreasonably achievable.

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Where are ALARA principles utilized?Where are ALARA principles utilized?

ALARA principles can be utilized in an infinite number of

situations. For example, the proper design of a nuclearfacility depends on ALARA considerations (e.g., can theaddition of more shielding to an area be justified interms of the lower doses it will achieve?). In addition,designing an x-ray facility for medical applications

requires consideration of the amount of shielding neededto ensure that individuals located near the facility (e.g.,on the other side of the wall from the x-ray unit) do notreceive any more dose than is really necessary duringoperation of the x-ray device.

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Why is emphasis regarding ALARAWhy is emphasis regarding ALARAimplementation placed first on physical designimplementation placed first on physical designfeatures at a nuclear facility rather than onfeatures at a nuclear facility rather than onprocedures, administration, or personalprocedures, administration, or personalpractices?practices?

The design of a nuclear facility is very important in the

eventual success of an effective ALARA program. Ifdesigned satisfactorily, worker doses and releases ofradioactivity to the environment can not only becontrolled but reduced. An improperly designed facility,on the other hand, may require subsequent

modifications, often at considerable expense to reachthe desired dose rates and with a corresponding impacton existing operations. While procedures, etc. areimportant as well, they represent a secondary, ratherthan primary, layer of support.

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What are the essential components in an ALARAWhat are the essential components in an ALARAprogram?program?

Generally speaking, a successful ALARA program requires

an appreciation, understanding, and acceptance fromeach individual involved in work with radioactivity andradiation-producing machines. More specifically, anALARA program must have some (preferably all) of thefollowing: a strong commitment from facility

management at all levels and throughout the entireorganization, dedicated staff, an ALARA program manualor approved program procedures, education and trainingprograms, a well-defined ALARA organization withestablished responsibilities, a Radiological SafetyCommittee which reports to upper management onALARA issues, and routine internal and external audits of

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How can the source of radiation be eliminated?How can the source of radiation be eliminated?(ALARA Principle #1)(ALARA Principle #1)

Eliminating the source of radiation can be accomplished by

substituting other appropriate technologies or materials.For example, using an ultrasound exam (sonogram) inprenatal examinations, rather than an x-ray exam, is amuch preferred practice due to the type of radiationreceived by the fetus.

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What do we mean by "source reduction"?What do we mean by "source reduction"?(Continuation of ALARA Principle #1)(Continuation of ALARA Principle #1)

Source reduction is a reduction in the dose rate (the time

over which the dose is delivered). Several methods areavailable. These include installing filtration andprocessing equipment to capture radioactive sourcesbefore they can reach populated areas, removal of non-essential radioactive materials or equipment from the

vicinity of personnel, selection of appropriate materialsto minimize radioactivity depositing on surfaces,

Continue.

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Is there an example showing an ALARAIs there an example showing an ALARAconsideration in equipment decontamination?consideration in equipment decontamination?

Yes. In this case, the method chosen to reduce the dose

(internal and external) to the worker during thedecontamination must be given some thought, while atthe same time, reducing the volume of radwasteproduced and the cost of the decontamination. In manyradiological situations, not every method selected is

appropriate for a particular radionuclide or surface.

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Can I accomplish source reduction in any otherCan I accomplish source reduction in any otherway?way?

Yes. If practical, allow the radionuclide source(s) to decay

for several half-lives. This is a passive (rather thanactive) approach relying on the nuclide's radioactiveproperties. It is feasible in those situations where thehalf-life is short enough (e.g., minutes, days) to produceacceptable results in a short period of time.

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By what means can radioactivity be controlledBy what means can radioactivity be controlledand contained? (ALARA Principle #2)and contained? (ALARA Principle #2)

This ALARA principle can be considered a subset of the first

principle and involves containment, ventilation, andfiltration.

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What is containment?What is containment?

Containment involves using leak-tight or controlled-

opening enclosures to prevent radioactive materialsfrom migrating to areas where we don't want them.Containment may be used temporarily and then removedafter the job is complete, or be a permanent component(as, for example, from a structural standpoint).

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What is the principle behind ventilation?What is the principle behind ventilation?

Ventilation is the flow of air and other gases in a certain

direction and rate such that radioactive airborneparticles and gases are captured and directed tocollection filters, followed by release to the atmosphereonce appropriate release limits have been met. A well-designed ventilation system will go a long way in limiting

the potential for intakes of radioactive material. Forexample, designing the flow of air containing radioactivematerials so that it moves away from people will help toensure that they don't receive unnecessary exposure.

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What is filtration?What is filtration?

Filtration ("filtering") is the capture of airborne particles

on a medium (like a vacuum cleaner bag), which canthen be disposed of in an acceptable manner.

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What protective designs are used in containmentWhat protective designs are used in containmentand confinement?and confinement?

To meet ALARA objectives in a radiation protection

program, it may be necessary to use some or all of thefollowing items: ventilated fume hoods, gloveboxes(used to handle radioactive materials), exhaust systems,water filtration and processing systems, ventilationcleanup systems, and double-walled pipes and tanks,

leak-tight valves, etc.

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What is the importance of time and itsWhat is the importance of time and itsrelationship to ALARA? (ALARA Principle #3)relationship to ALARA? (ALARA Principle #3)

Simply put, the less time spent in a radiation field, the

lower the dose. To meet ALARA goals, no more timeshould be spent in a radiation field than is necessary toperform the required tasks. There are several designfactors which can be utilized in a nuclear facility topromote this principle. For example, personnel who have

to work in the vicinity of radioactive sources oftenconduct rehearsals in low dose areas to ensure that theykeep their time in the area to a minimum, that theyhave all the tools they need, etc. (The concept ofexposure time is discussed in further detail in thewebpage chapter entitled "External Exposure Control".)

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How is distance incorporated into ALARAHow is distance incorporated into ALARAplanning? (ALARA Principle #4)planning? (ALARA Principle #4)

In the case of distance, the further away from a radiation

source you are, the lower the dose. This is especiallytrue for "point" sources of radiation which follow theinverse-square law. As with time, several design factorsare available to aid in maximizing the distance fromradioactive sources. (The concept of distance is also

discussed in further detail in the chapter on "ExternalExposure Control".)

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Explain the concept of shielding (ALARAExplain the concept of shielding (ALARAPrinciple #5)Principle #5)

Shielding involves the use of different materials placed

between the worker and the source to absorb theradiation. The choice of shielding depends on the type ofradiation and may either be temporary or permanent. Aswith time and distance, several design factors areavailable to reduce worker dose. (Once again, be sure to

review the webpage chapter on "External ExposureControl" for more information about shielding.)

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What do we mean by "Optimization"? (ALARAWhat do we mean by "Optimization"? (ALARAPrinciple #6)Principle #6)

Optimization sounds impressive and maybe a little

intimidating when you first hear it, but the concept (notnecessarily the application!) is pretty straightforward. Inan ALARA design, cost-benefit analyses are performed tobalance economic considerations with the expectedbenefits. Optimization is used to demonstrate that any

expenses involved - in terms of money, time spent bypersonnel, dose received, etc. - is justified in terms ofthe benefit received. In so doing, reducing radiationexposures can be weighed against competing conflicts(technical considerations, social, operational, andeconomic).

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In general, what three phases in the ALARAIn general, what three phases in the ALARAprocess are examined in performing workprocess are examined in performing workactivities in a radiological area?activities in a radiological area?

Working in an area containing radiation and/or radioactive

materials requires pre-job planning (the extent of whichdepends on the complexity of the job), implementationof pre-established ALARA controls and tracking of workerdoses, and a post-job review to evaluate the "lessonslearned". These steps allow the application of ALARA

principles before the job is started, ensure that theprinciples are being applied correctly, and assist inimproving performance on future jobs.

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Where can I obtain more information about theWhere can I obtain more information about theALARA concept?ALARA concept?

There are a number of excellent references that discuss

ALARA, its basis and its implementation in great detail.Quite a few of them are listed in the "Bibliography" thatis located in this web page's "Tool Box" (press the redbutton on the left). If you don't find the information youneed there, please don't hesitate to "Ask a CHP".

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Session for

QuestionQuestion

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TRUE or FALSE?TRUETRUE or FALSE?SpecialT

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Mr.Muahamma

dAshfaqIncharge

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