PNFX7101 M - Radiation Safety Brief

8/2/2019 PNFX7101 M - Radiation Safety Brief

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ACADEMY OF HEALTH SCIENCES M PNFX7101DEPARTMENT OF PREVENTIVE HEALTH SERVICES 0508

NUCLEAR, BIOLOGICAL, CHEMICAL SCIENCES BRANCH

Radiation Safety Briefing

REFERENCES:

Hall, Eric J.; Radiobiology for the Radiologist, 5th ed., Philadelphia: Lippincott Williams &Wilkins, 2000

AR 11-9, The Army Radiation Safety Program, 28 May, 1999TB MED 521, Management and Control of Diagnostic X-ray, Therapeutic X-ray and Gamma-

beam Equipment, June 1981

TERMINAL LEARNING OBJECTIVE:

Identify the potential radiation hazards in diagnostic radiology and the precautionsnecessary to maintain exposures as low as reasonably achievable as well as describe

recommended measures to maintain total fitness.

ENABLING LEARNING OBJECTIVE:

1. Given a DD 1952, properly complete the Dosimeter Application IAW AR 11-9.

2. Given a list of radiation effects, select the statement which describes that effect IAW Hall.

3. Given a list of statements about radiation protection, select the statement whichdescribes the as-low-as-reasonably-achievable (ALARA) concept IAW AR 11-9.

NOTES

A. DD Form 1952, Dosimeter Application and Record of Occupational Radiation Exposure

1. For the X-ray survey class, complete cells indicated in Figure 1 (left). Under pay grade,civilians should either Check the box or print CIV In the box. For military, print yourgrade (e.g., E-5, O-2). Include the address to send the dosimetery results to, for moststudents, this will be the address of the office where dosimetry results are maintained oryour office address. Turn over form to sign.

2. On the reverse, review the Privacy Act. The only item of concern is the Social SecurityNumber. This number is used to uniquely identify the wearer. For non-US residentswithout an SSN, another unique identifier (e.g., passport number, Social Insurance

Number, etc.) is used. The birthdate is not Privacy Act data, it is used to verify that theapplicant is older than 18 years of age.


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M PNFX70508

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5/23

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M PNFX70508

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9

Chernobyl. Most of these effects require an acute exposure in excess of 2 Gy (200 rad).Some of the well documented deterministic effects include:

a. Acute Radiation Injury - Acute, large doses of radiation may damage a sufficientnumber of radiosensitive cells to produce mild symptoms of radiation sickness withina few days to a few weeks. The immediate somatic effects may include symptomssuch as blood changes, nausea, vomiting, hair loss, diarrhea, dizziness, nervousdisorders, hemorrhage, and maybe death. Without medical care, half of the peopleexposed to a whole body acute exposure of 4 Gy (400 rad) may die within 60 days(LD50/60). Regardless of care, persons exposed to an acute exposure exceeding 7Gy (700 rad) are not likely to survive (LD100). Exposed individuals who survive acutewhole body exposures may also develop other delayed somatic effects such asepilation, cataracts, erythema, sterility and/or cancers.

(1) Hematopoietic syndrome (1 - 8 Gy) - The hematopoietic stem cells are the most

radiosensitive tissues in the body. Radiation doses of 2 Gy (200 rad) or morecan damage the blood forming capability of the body. Acute doses kill some ofthe mitotically active precursor stem cells, diminishing the subsequent supply ofmature red cells, white cells, and platelets. As mature circulating cells die andthe supply of new cells is inadequate to replace them, the physiologicalconsequences of hematopoietic system damage become manifest. TheHematopoietic syndrome includes such symptoms as increased susceptibility toinfection, bleeding, anemia, and lowered immunity. One of the principal causesof death after total-body irradiation is infection. For doses below 7 Gy (700 rad),the hematopoietic syndrome starts about 8 - 10 days post exposure with aserious drop in granulocyte and platelet counts. Pancytopenia (i.e., reduction ofall types of blood cells) follows about 3 - 4 weeks later, becoming complete at

doses above 5 Gy (500 rad). Petechiae (small hemorrhage under the skin) andpurpura are evident, and bleeding may be uncontrolled, causing anemia. Theremay be fever and rises in pulse and respiratory rates due to endogenousbacterial and mycotic infections. The infections may become uncontrolled due toimpaired granulocyte and antibody production. If at least 10% of thehematopoietic stem cells remain uninjured, recovery is possible. Otherwise,death occurs within 4 - 6 weeks.

(2) Gastrointestinal syndrome (8 - 30 Gy) - At doses above 8 Gy (800 rad), injury tothe gastrointestinal tract contributes increasingly to the severity of the manifest-illness phase. Such high exposures inhibit the renewal of the cells lining thedigestive tract. These cells are short lived and must be renewed at a high rate.

High exposures then lead to depletion of these cells within a few days. Thephysiological consequences of gastrointestinal injury may vary depending uponthe region and extent of damage. The small intestine contains the most sensitiveof these tissues followed by the stomach, colon, and rectum. The mouth andesophagus respond similarly to the skin. Thus, the result of high exposures is abreakdown of the mucosal lining and ulceration of the intestine. As the mucosabreaks down, bacteria can enter the bloodstream and are unchallenged becauseof the curtailed production of granulocytes. Beginning at approximately 12.5 Gy(1250 rad), early mortality occurs due to dehydration and electrolyte imbalance


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10

from leakage through the extensively ulcerated intestinal mucosa. Theseconditions develop over a few days and are characterized by cramping,abdominal pain, and diarrhea, followed by shock and death.

(3) Central nervous system syndrome (> 30 Gy) - CSN symptoms are identifiedalmost immediately and consist of disorientation, apathy, ataxia, prostration andoften tremor and convulsions. The cause of death includes vascular damage,meningitis, myelitis, and encephalitis. Fluid infiltrates into the meninges, brainand choroid plexus causing edema, this pressure may cause pressure on criticalstructures.

b. Cataracts seem to have a threshold of about 2 Gy (200 rad) and are more probablefrom acute neutron doses. They tend to have a long latent period. They can bedistinguished from age-induced cataracts because senile cataracts begin in theanterior pole of the lens whereas radiation cataracts begin as a small dot in the

posterior pole.

c. Hair loss (epilation) can occur after acute doses of 2 - 5 Gy (200 - 500 rad).Temporary hair loss in radiotherapy patients begins in about 3 weeks and hair beginsto return during the second month continuing up to 1 year. Single doses of 7 Gy(700 rad) may cause permanent epilation with a latent period of less than 3 weeks.Hair follicles of children are more sensitive than those of adults. Body hair tends tobe less sensitive than the scalp and beard.

d. Skin erythema (reddening) occurs from a single dose of 6 - 8 Gy (600 - 800 rad) witha threshold of 4 Gy (400 rad) in sensitive individuals. The higher the radiation dose,the more quickly the erythema appears. Early erythema is thought to be due to the

release of vasoactive amines. Erythema increases during the first week and usuallyfades during the second week, only to return and may last for 20 - 30 days.

e. Sterility, depending on dose may be either temporary or permanent in males.Although females require a higher dose, sterility is usually permanent. The femalethreshold for permanent sterility usually requires doses exceeding 2 Gy (200 rad) tothe reproductive cells. Male, temporary sterility may occur at a threshold of 0.5 Gy(50 rad).

13. Stochastic / probabilistic effects have been demonstrated through epidemiological studiesof acutely exposed populations. The two main categories of stochastic effects arecarcinogenic and genetic.

a. Cancer - Radiation is considered a generic carcinogen. That is, while cancersmay be produced by ionizing radiation, the cancers are indistinguishable fromspontaneous or non-radiation cancers. Additionally, there is usually a long,variable latent period (> 5 to 30 years) from radiation exposure to cancermanifestation, making cause and effect difficult to identify. Another reason it isdifficult to pin-point cause is that the normal cancer incidence is relatively high(i.e., the fatal cancer risk from all causes in the U.S. is about 20% or one personin five), the number of cancers expected from radiation exposure are a fraction of


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13/23

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M PNFX70508

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5. Radiation Protection Office Location and Staff

1. RPO: Location: Rm 0410, Willis Hall

2. Telephone: x6011/6632

3. Dosimetry Coordinator: x2614/1869


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APPENDIX AINSTRUCTOR'S GUIDE

EFFECTS ON THE EMBRYO/FETUSOF EXPOSURE TO RADIATION AND OTHER ENVIRONMENTAL HAZARDS

In order to decide whether to continue working while exposed to ionizing radiation during her pregnancy,a woman should understand the potential effects on an embryo/fetus, including those that may beproduced by various environmental risks such as smoking and drinking. This will allow her to comparethese risks with those produced by exposure to ionizing radiation.

Table 1 provides information on the potential effects resulting from exposure of an embryo/fetus toradiation and nonradiation risks. The second column gives the rate at which the effect is produced bynatural causes in terms of the number per thousand cases. The fourth column gives the number ofadditional effects per thousand cases believed to be produced by exposure to the specified amount of therisk factor.

The following section discusses the studies from which the information in Table 1 was derived. Theresults of exposure of the embryo/fetus to the risk factors and the dependence on the amount of theexposure are explained.

RADIATION RISKS

Childhood CancerNumerous studies of radiation-induced childhood cancer have been performed, but a number of them arecontroversial. The National Academy of Science (NAS) BEIR report reevaluated the data from thesestudies and even reanalyzed the results. Some of the strongest support for a casual relationship isprovided by twin data from the Oxford survey. For maternal radiation doses of 1,000 millirems, theexcess number of deaths (above those occurring from natural causes) was found to be 0.6 death perthousand children.

Mental Retardation and Abnormal Smallness of the Head (Microcephaly)Studies of Japanese children who were exposed while in the womb to the atomic bomb radiation atHiroshima and Nagasaki have shown evidence of both small head size and mental retardation. Most ofthe children were exposed to radiation doses in the range of 1 to 50 rads. The importance of the mostrecent studies lies in the fact that investigators were able to show that the gestational age (age of theembryo/fetus after conception) at the time the children were exposed was a critical factor. Theapproximate risk of small head size as a function of gestational age is shown in Table 1. For a radiationdose of 1,000 millirems at 4 to 7 weeks after conception, the excess cases of small head size was 5 perthousand; at 8 to 11 weeks, it was 9 per thousand.

In another study, the highest risk of mental retardation occurred during the 8 to 15 week period afterconception. A recent EPA study has calculated that excess cases of mental retardation per live birth lie

between 0.5 and 4 per thousand per rad.

Genetic EffectsRadiation-induced genetic effects have not been observed to date in humans. The largest source ofmaterial for genetic studies involves the survivors of Hiroshima and Nagasaki, but the 77,000 births thatoccurred among the survivors showed no evidence of genetic effects. For doses received by thepregnant worker in the course of employment considered in this guide, the dose received by theembryo/fetus apparently would have a negligible effect on descendants.


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NONRADIATION RISKS

Occupation

A recent study involving the birth records of 130,000 children in the State of Washington indicates that therisk of death to the unborn child is related to the occupation of the mother. Workers in the metal industry,the chemical industry, medical technology, the wood industry, the textile industry, and farms exhibitedstillbirths or spontaneous abortions at a rate of 90 per thousand above that of workers in the controlgroup, which consisted of workers in several other industries.

AlcoholIt has been recognized since ancient times that alcohol consumption had an effect on the unborn child.Carthaginian law forbade the consumption of wine on the wedding night so that a defective child mightnot be conceived. Recent studies have indicated that small amounts of alcohol consumption have onlythe minor effect of reducing the birth weight slightly, but when consumption increases to 2 to 4 drinks perday, a pattern of abnormalities called the fetal alcohol syndrome (FAS) begins to appear. This syndromeconsists of reduced growth in the unborn child, faulty brain function, and abnormal facial features. Thereis a syndrome that has the same symptoms as full-blown FAS that occurs in children born to mothers who

have not consumed alcohol. This naturally occurring syndrome occurs in about 1 to 2 cases perthousand.

For mothers who consume 2 to 4 drinks per day, the excess occurrences number about 100 perthousand; and for those who consume more than 4 drinks per day, excess occurrences number 200 perthousand. The most sensitive period for this effect of alcohol appears to be the first few weeks afterconception, before the mother-to-be realizes she is pregnant. Also, 17% or 170 per thousand of theembryo/fetuses of chronic alcoholics develop FAS and die before birth. FAS was first identified in 1973 inthe United States where less than full-blown effects of the syndrome are now referred to as fetal alcoholeffects (FAE).

SmokingSmoking during pregnancy causes reduced birth weights in babies amounting to 5 to 9 ounces on the

average. In addition, there is an increased risk of 5 infant deaths per thousand for mothers who smokeless than one pack per day and 10 infant deaths per thousand for mothers who smoke one or more packsper day.

MiscellaneousNumerous other risks affect the embryo/fetus, only a few of which are touched upon here. Most peopleare familiar with the drug thalidomide (a sedative given to some pregnant women), which causes childrento be born with missing limbs, and the more recent use of the drug diethylstilbestrol (DES), a syntheticestrogen given to some women to treat menstrual disorders, which produced vaginal cancers in thedaughters born to women who took the drug. Living at high altitudes also gives rise to an increase in thenumber of low-birth-weight children born, while an increase in Down's Syndrome (mongolism) occurs inchildren born to mothers who are over 35 years of age. The rapid growth in the use of ultrasound inrecent years has sparked an ongoing investigation into the risks of using ultrasound for diagnostic

procedures.


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TABLE 1. EFFECTS OF RISK FACTORS ON PREGNANCY OUTCOME

Effect

Number Occurring

from Natural Causes Risk Factor

Excess Occurrence

from Risk Factor

RADIATION RISK

Childhood Cancer

Cancer death in children 1.4 per thousand Radiation dose of 1000 mremreceived before birth

0.6 per thousand

Abnormalities Radiation dose of 1000 mrem received during specificperiods after conception:

Small head size 40 per thousand 4-7 weeks after conception 5 per thousand

Small head size 40 per thousand 8-11 weeks after conception 9 per thousand

Mental retardation 4 per thousand Radiation dose of 1000 mremreceived 8 to 15 weeks after

conception

4 per thousand

NON-RADIATION RISKS

Occupation

Stillbirth or spontaneousabortion

200 per thousand Work in high-risk occupations(see text)

90 per thousand

Alcohol Consumption

Fetal alcohol syndrome 1 to 2 per thousand 2 - 4 drinks per day 100 per thousand

Fetal alcohol syndrome 1 to 2 per thousand More than 4 drinks per day 200 per thousand

Fetal alcohol syndrome 1 to 2 per thousand Chronic alcoholic (more than10 drinks per day)

350 per thousand

Perinatal infant death(around the time of birth)

23 per thousand Chronic alcoholic (more than10 drinks per day)

170 per thousand

Smoking

Perinatal infant death 23 per thousand Less than 1 pack per day 5 per thousand

Perinatal infant death 23 per thousand One pack or more per day 10 per thousand


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APPENDIX BPREGNANT WORKER'S GUIDE

POSSIBLE HEALTH RISKS TO CHILDRENOF WOMEN WHO ARE EXPOSED TO RADIATION DURING PREGNANCY

During pregnancy, you should be aware of things in your surroundings or in your style of life that couldaffect your unborn child. For those of you who work in or visit areas designated as Restricted Areas(where access is controlled to protect individuals from being exposed to radiation and radioactivematerials), it is desirable that you understand the biological risks of radiation to your unborn child.

Everyone is exposed daily to various kinds of radiation: heat, light, ultraviolet, microwave, ionizing, andso on. For the purposes of this guide, only ionizing radiation (such as x-rays, gamma rays, neutrons, andother high-speed atomic particles) is considered. Actually, everything is radioactive and all humanactivities involve exposure to radiation. People are exposed to different amounts of natural "background"ionizing radiation depending on where they live. Radon gas in homes is a problem of growing concernand is estimated to contribute an average of 150 mrem per year to the average annual dose.

Background radiation comes from three sources (other than radon):

Source Average Annual Dose

Terrestrial -- radiation from soil and rocks 50 millirem

Cosmic -- radiation from outer space 50 millirem

Radioactivity normally found within the humanbody

25 millirem

TOTAL: 125 millirem

Dosage range (geographic and other factors) 75 to 5,000 millirem

NOTE: Radiation doses in this document are described in two different units. The rad is a measure ofthe amount of energy absorbed in a certain amount of material (100 ergs per gram). Equalamounts of energy absorbed from different types of radiation may lead to different biologicaleffects. The rem is a unit that reflects the biological damage done to the body. The millirad andmillirem refer to 1/1000 of a rad and a rem, respectively.

The first two of these sources expose the body from the outside, and the last one exposes it from theinside. The average person is thus exposed to a total dose of about 125 millirems per year from naturalbackground radiation.

In addition to exposure from normal background radiation, medical procedures may contribute to the dosepeople receive. On average, people receive about 40 mrem per year from medical sources, although the

exposure to individuals are highly variable, depending on the specific procedures that the individual hasbeen subjected. The following table lists the average doses received by the bone marrow (theblood-forming cells) from different medical applications.


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X-Ray Procedure Average Dose

Normal chest examination 10 millirem

Normal dental examination 10 millirem

Rib cage examination 140 millirem

Gall bladder examination 170 millirem

Barium enema examination 500 millirem

Pelvimetry examination 600 millirem

NOTE: Variations by a factor of 2 (above and below) are not unusual.

NRC POSITION

NRC regulations and guidance are based on the conservative assumption that any amount of radiation,

no matter how small, can have a harmful effect on an adult, child or unborn child. This assumption is saidto be conservative because there are no data showing ill effects from small doses; the National Academyof Sciences recently expressed "uncertainty as to whether a dose, of say, 1 rad would have any effect atall". Although it is known that the unborn child is more sensitive to radiation than adults, particularlyduring certain stages of development, the NRC has not established a special dose limit for protection ofthe unborn child. Such a limit could result in job discrimination for women of child-bearing age andperhaps in the invasion of privacy (if pregnancy tests were required) if a separate regulatory dose limitwere specified for the unborn child. Therefore, the NRC has taken the position that special protection ofthe unborn child should be voluntary and should be based on decisions made by workers and employerswho are well informed about the risks involved.

For the NRC position to be effective, it is important that both the employee and the employer understandthe risk to the unborn child from radiation received as a result of the occupational exposure of the mother.

This document tries to explain the risk as clearly as possible and to compare it with other risks to theunborn child during pregnancy. It is hoped this will help pregnant employees balance the risk to theunborn child against the benefits of employment to decide if the risk is worth taking. This document alsodiscusses methods of keeping the dose, and therefore the risk, to the unborn child as low as isreasonably achievable.

RADIATION DOSE LIMITS

The NRC's present limit on the radiation dose that can be received on the job is 1,250 millirems perquarter (3 months) (NOTE: The limit is 3,000 millirems per quarter if the worker's occupational dosehistory is known and the average dose does not exceed 5,000 millirems per year.) Working minors(those under 18) are limited to a dose equal to one-tenth that of adults, 125 millirems per quarter.

Because of the sensitivity of the unborn child, the National Council on Radiation Protection andMeasurements (NCRP) has recommended that the dose equivalent to the unborn child from occupationalexposure of the expectant mother be limited to 500 millirems for the entire pregnancy. The 1987Presidential guidance specifies an effective dose equivalent limit of 500 millirems to the unborn child if thepregnancy has been declared by the mother; the guidance also recommends that substantial variations inthe rate of exposure be avoided. The NRC has proposed adoption of the above limits on dose and rate ofexposure.

ADVICE FOR EMPLOYEE AND EMPLOYER


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Although the risks to the unborn child are small under normal working conditions, it is still advisable tolimit the radiation dose from occupational exposure to no more than 500 millirems for the total pregnancy.Employee and employer should work together to decide the best method for accomplishing this goal.Some methods that might be used include reducing the time spent in radiation areas, wearing someshielding over the abdominal area, and keeping an extra distance from radiation sources when possible.The employer or health physicist will be able to estimate the probable dose to the unborn child during thenormal nine-month pregnancy period and to inform the employee of the amount. If the predicted doseexceeds 500 millirems, the employee and employer should work out schedules or procedures to limit thedose to the 500-millirem recommended limit.

It is important that the employee inform the employer of her condition as soon as she realizes she ispregnant if the dose to the unborn child is to be minimized.

INTERNAL HAZARDS

This document has been directed primarily toward a discussion of radiation doses received from sources

outside the body. Workers should also be aware that there is a risk of radioactive material entering thebody in work places where unsealed radioactive material is used. Nuclear medicine clinics, laboratories,and certain manufacturers use radioactive material in bulk form, often as a liquid or a gas. A list of thecommonly used materials and safety precautions for each is beyond the scope of this document, butcertain general precautions might include the following:

1. Do not smoke, eat, drink, or apply cosmetics around radioactive material2. Do not pipette solutions by mouth3. Use disposable gloves while handling radioactive material when feasible4. Wash hands after working around radioactive material5. Wear lab coats or other protective clothing whenever there is a possibility of spills.

Remember that the employer is required to have demonstrated that it will have safe procedures and

practices before the NRC issues it a license to use radioactive material. Workers are urged to followestablished procedures and consult the employer's radiation safety officer or health physicist wheneverproblems or questions arise.

Documents

PNFX7101 M - Radiation Safety Brief