The Biological and Medical Effects of Radiation

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The Biological and Medical Effects of Radiation

The Biological and Medical

Effects of Radiation

By

James Waris

Rene Alonso


Atomic Bomb in Hiroshima

• Video


Types of Radiation

There are many types of radiation.

• Different wavelengths across electromagnetic

spectrum

Thermal, residual, ionizing

• Ionizing radiation is what is dangerous to living

cells.

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What is Ionizing Radiation?

• High energy radiation

• Can penetrate matter

• Ejects electrons from atomic orbits

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Types of Ionizing Radiation

• Gamma Rays

• X-Rays

• Alpha Particles

• Beta Particles

• Neutrons

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Effects of Radiation on Cells

• Living tissues are injured due to the

transfer of energy to the molecules in the

cellular structure.

These molecules become excited and the

following can result:

• Production of free radicals

• Breakage of chemical bonds

• Damage to molecules that regulate

essential processes (ie. DNA and RNA)


Effects of Ionizing Radiation

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Effects on Different tissues

• Cells with a high rate of

division are most

vulnerable to damage by

radiation

• Blood-forming organs and

reproductive organs are

most vulnerable.

• Skin, bone and teeth, and

muscle intermediate

• Nervous system is the

least vulnerable

• Developing embryos most

sensitive

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Background Radiation

We are constantly surrounded and exposed to low

levels of radiation on a daily basis. In the US, we

receive a dose of around 100 mrem of radiation from

the environment each year. (Although this can very

greatly depending on where you live.) This comes from

a variety of sources:

•Cosmic Rays from Space

~44mrem

•Gamma radiation from external

radioactivity ~40 mrem

•Internal radiation ~18 mrem


Medical Radiation

• In addition to the radiation we receive from

the environment, we also receive an

annual dose of around 50 mrem from

medical sources.

• This includes techniques such as x-rays

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Danger of Low Dose Radiation

• Low dose radiation sustained over a long

period of time may increase risk of cancer.

• Difficult to determine effects, because

levels l so similar il to background levels.

l

• If risks exist they are minimal

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Putting Danger into Perspective

The following all have a

one in a million chance of

death.

• Exposure to 10 mrem

dose of radiation

• Smoking 1.4 cigarettes in

a lifetime (lung cancer)

• Spending two days in New

York City (air pollution)

• Driving 40 miles in a car

(accident)

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Putting Risk into Perspective

• A 1991 NRC draft guide attempted to place an estimate

on the loss of life expectancy from exposure to 300mrem

of radiation (average occupational exposure).

• Dose of 300 mrem/year – 15 days

• Smoking 20 cigarettes a day – 6 years

• Overweight by 15% - 2 years

• All accidents – 207 days

• Alcohol (US average) – 1 year

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High Dose Exposure

• Acute Whole-body exposure to high doses

of radiation results in irreversible damage

to cells. The exact consequences depend

on the amount and length of exposure.

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Acute Effects of Whole Body

Exposure

Dose

(Rem)

5-20

Effect

20 Possible Chromosome damage

Goldman, 1982

20-100

100 Temporary Reduction in Leukocytes

>50 = temporary sterility in men

100- Mild Radiation sickness (vomiting, diarrhea,

200 fatigue, reduced d immune)

200- Serious Radiation sickness (above plus bone

300 marrow sickness and hemorrhage h LD 10-35/30)


Dose

(Rem)

300-400

400

1000

Acute Effects of Whole Body

Exposure

Effect

400 Serious Radiation Sickness plus bone-marrow and

intestine destruction. Sterility in women.

LD 50-70/30

400- Acute illness, early death; LD 60-95/30

1000

5000

>5000

1000- Acute illness, death in days. LD 100/10

>5000 Acute illness, death in hours-days; central nervous

syndrome. LD 100/2

Goldman, 1982


Lethal Doses

• Mammals LD 50 =350-800 rem

• Bacteria LD 50 ~5000 rem

• Lethal dose for insects shows a lot of

variability. As high as 100-500 kilorems

for some species.

• Plants: LD 50 is in the kilorads

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Atomic Blast

(Hiroshima/Nagasaki)

• Types of Radioactive

Exposure:

Thermal Burns (infrared

heat radiation)

• Beta Burns (ionizing

radiation on fallout

particles)

• Gamma Burns (highly

penetrating)


Different Stages

– Initial Stage

• First 1-2 weeks.

• Greatest number of deaths.

• 90% due to thermal burns/ blast effects

• 10% due to superlethal radiation exposure

• Blast Effects- pressure over .8 bar

destroys most buildings.

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Different Stages

– Intermediate

• Deaths occurring after 3-8 weeks

• Deaths due to ionizing radiation in median

lethal range

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Different stages - Late

• Period 8-20 weeks after blast

• Characterized by improvement in survivors

conditions


Different Stages - Delayed

• 20+ weeks after blast.

• Complications from wounds

• Infertility

• Blood Disorders

• Genetic effects

• Birth Defects

• Cancer

• Cataracts

t

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Levels at Hiroshima/Nagasaki

1 Sievert =

100 Rem


A-bomb Survivors

• Almost half of all leukemia cases in A-

bomb survivors were attributable to

radiation from the blast.

• As of 1990, 4,565 solid cancer deaths.

8% attributable to radiation.

• As much as 70% of cancers from A-bomb

radiation are expected to appear in the

next 20 years.


Famous Survivors

• Sadako Sasaki

• 2 years old in 1945

• Exposed to Hiroshima

Radiation

• 1954- red/purple spots

appear (symptoms of

Leukemia)

• 1000 paper cranes

• Dies 1955

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Chernobyl – 1986 Ukraine

• Plutonium, noble

gases, and fission

products released into

environment

• Iodine and strontium

most dangerous (food

chain)

• 56 direct deaths.

• According to WHO

estimates, as many as

4,000 extra cancer

deaths caused by

radiation.


• Hundreds of times

more radioactivity

released than

Hiroshima bomb

• Radioactivity longer

lived

• Thousands of years

before accident site

will be completely

safe.

• ~200 years before it

will be safe to resume

agriculture in the

surrounding area.

Chernobyl


Biological Effects

• Radioactive Reaction products released

(included I-131, Cs-137, Sr-90)

• Most dangerous accumulate in food chain

• I-131 accumulates in Thyroid gland

• Thyroid- endocrine gland, controls how fast body

uses energy, rate of protein production, and how

sensitive body is to other hormones

• Hyperthyroidism

• Thyroid Cancer


Questions

• Should the US government pay for medical

treatment costs of Hiroshima and Nagasaki

survivors?

• What should the future of nuclear power be?

Should we expand the industry even though

there have been accidents in the past?

• Reactor accidents have the potential to affect

those in other countries? Do you think that

nuclear power should be under international

regulation and inspection or should it be left up

to the individual country?


Radiation Poisoning

• Illness and symptoms resulting from

excessive exposure to radiation.

Exposure may be accidental or intentional.

• Due to two types of radiation

• Ionizing: produces immediate chemical effects

on human tissue (rays, gamma rays, and

particle bombardment). Can be used for

medical testing and treatment, industrial and

manufacturing purposes, weapons and

weapons development, etc.


Continued

• Nonionizing: radiation from light, radio waves,

microwaves and radar. Usually no harm to tissue.

Radiation exposure:

• Acute:

• single large exposure

• Usually associated with radiation sickness

• Chronic:

• A series of small exposures spread over time

• Associated with delayed medical problems such as cancer

and premature aging.


Acute

• Mild exposure (1-2 Gy) doses of

radiation

• Moderate exposure (2-3.5 Gy) doses

of radiation

• Severe exposure (3.5-5.5 5.5 Gy) doses

of radiation

• Very severe (5.5-8 5 Gy) doses of radiation

• X-rays or Gamma Rays

• 1 Gy causes radiation sickness

• 4 Gy causes radiation sickness and death in half of

individuals.

• Without medical treatment almost all exposed will die within 30

days.

• 1000 Gy immediate unconsciousness and death within an

hour.


Symptoms

• Appear sooner with higher doses of exposure.

• Become more serious as the dosage of radiation

increases.

• Main symptoms are nausea and vomiting.

• 24-4848 hours in mild exposure.

• 12-2424 hours in moderate exposure

• Less than 1 hour in severe exposure

• Less than 30 minutes in very severe exposure.


Symptoms by severity

• Mild

• Nausea and vomiting, headaches, fatigue, and weakness

• Moderate

• All symptoms of mild, fever, hair loss, infections, bloody vomit

and stools, poor wound healing.

• Severe

• All symptoms of lower levels, diarrhea, high fever

• Very Severe

• All symptoms of lower levels, dizziness, disorientation, low blood

pressure

• Fatal about 50% of the time.


Syndromes

• Prodromal Syndrome

• 15G

1.5 Gy

• causes gastrointestinal distress such as anorexia, nausea, fatique, and

diarrhea

• Bone Marrow Death

• 2 to 10 Gy

• Production of red and white blood cells and platelets is stopped by

division of precursor stem cells.

• Loss of platelets greatly increases the chance of fatal hemorrhage.

• Gastrointestinal Death

• 1 to 5 Gy

• Causes damage to epithelial cells lining gastrointestinal tract

• Death in 7-14 days from loss of water and electrolytes

• Central Nervous System Death

• Main cause of death in 24-4848 hours


Short Term Effects (6-8 Wks)

• Skin

• Germinal layer is the principal i site of damage

• Initial response is erythema (reddening)

• Due to blood vessel congestion and edema

• Lungs

• Most radiosensitive organ to radiation

Radiation pneumonitis

• Leads to pulmonary insufficiency and death in few months

• Ovaries

• Single dose 1-2 Gy will cause temporary sterility. Suppress

menstruation for up to 3 yrs. 4 Gy will cause permanent sterility.

• Testicles

• 0.1 Gy will cause low sperm count for up to a year.

• 2.5 Gy will cause sterility for 2 to 3 years or more.

• 4 Gy will cause permanent sterility.


Long Term Effects

• Cataract Induction

• Average time of development 2 to 3 years.

• 2 Gy of gamma rays cause opacities in few

• 6-7 Gy seriously impair vision and cause cataracts

• Cancer Induction

• Most significant risk of long exposure

• 1 in 80 exposed will die from cancer

• 1 in 40 will develop cancer

• Utero Effects

• 1 Gy dose will cause 0 to 20 extra cases of perinatal mortality per 1000

births.

• .05 Gy will increase death due to cancer 10 times per 1000 births.

• 1 Gy antenatal dose in first trimester causes the risk of fatal cancer to

increase to 100% of cases.


Long term Effects caused by

• Caused by

• Contaminated water

• Untreated sewage

• Crowded living conditions

• Poor standard of living

• Lack of vaccines

• Infectious Diseases caused by blast

• Dysentery

• Infectious hepatitis

• Salmonellosis:

ll • Cholera

• Menigococcal meningitis

• Tuberculosis

• Diphtheria

i

• Whooping Cough

• Polio

• Pneumonia

Nuclear Blast.


Testing and Diagnosis

• Known Exposure

• Details about distance from the source of radiation and duration of exposure

• Vomiting and other symptoms

• Time between radiation exposure and the onset of vomiting

• Shorter onset means higher dose of exposure

• Blood Tests

• Blood tests over several days

• Details drop in white blood cells and abnormal changes in DNA of

blood cells

• Dosimeter

• Indicate degree of bone marrow damage

• Device that can measure the absorbed dose of radiation but only

if it was exposed to radiation at the same time the person was

exposed.

• Survey Meter

• Device that can be used to survey people to determine the body

location of radiactive particles

• Type of radiation

• Provides guide to decisions for treating people with radiation sickness


First Aid to Radiation Exposure

• Only provide medical treatment if appropriate protective

gear is worn

• Check person’s breathing and pulse

• Start CPR, if necessary

• Remove clothing and seal in container

• Vigorously wash body with soap and water

• Dry body and wrap with soft, clean blanket

• Take person to nearest emergency medical facility

• Report Exposure to Emergency official.

• DO NOT

• Remain in area

• Apply ointments to burned areas

• Remain in contaminated clothing

• Refuse to see medical treatment


Treatments and Drugs

• Goals

• To prevent further radioactive contaminations,

ti

treat damaged organs, reduce symptoms, and

manage pain

• Decontamination

• Remove clothing and shoes to eliminate about

90% of external contamination.

• Lowers the risk of internal contamination from

inhalation, ingestion or open wounds.

• Treatment for damaged bone marrow

• Use of protein granulocyte colony-stimulating

factor

• Promotes the growth of white blood cells

• Neupogen and Neulasta

• Blood transfusions for

severe damage


Treatment continued

• Internal contamination

• Potassium Iodide

• Prevents absorption of radioiodine by thyroid.

• Allows for radioiodine to be cleared in urine

• Prussian blue

• Binds to particles of radioactive elements (Cesium and

thallium)

• Allows for excretion of radioactive elements

• Speeds up elimination and reduces the amount of radiation

cells absorb

• DTPA

• Binds to radioactive elements such as plutonium, americium,

curium.


Supportive Treatment

• Additional medications or interventions to treat:

• Bacterial infections

• Headaches

• Fever

• Diarrhea

• Nausea and Vomiting

• Dehydration

• End of life care

• Usually people who have absorbed radiation greater than 8 Gy.

• Control pain

• Nausea and vomiting

• Diarrhea


Benefits of Radiation

Therapy


What is Radiation Therapy?

Radiation therapy uses high powered x-rays or

radioactive seeds to kill cancer cells.

• Most harmful to cancer cells than normal cells.

• Prevents cancer cells from growing and dividing

• It is used to fight many types of cancer

• Used to shrink tumor before surgery.

• Used to prevent the return of cancer cells after

surgery

• Can be used to provide temporary relief of symptoms

or to treat malignancies that cannot be removed with

surgery


Radiation Therapy

• Three Types

• External beam radiation

• Most common form

• Uses high powered x-rays aimed directly at the tumor from the

outside of the body

• Kilovoltage x-rays

• Megavoltage x-rays

• Internal radiotherapy (Brachytherapy)

Radiation source placed inside

or next to the area requiring

treatment

• Commonly used in treating cervical, prostate,

breast.

• Unsealed source radiotherapy

• Use of soluble forms of radioactive substances

either by injection or ingestion.


Side Effects of Radiation Therapy

• Depend on the person, dose, and frequency of therapy.

• Hair loss

• Skin pain

• Red burning skin

• Increased skin coloring

• Itching

• Fatigue

• Low blood counts

• Edema

• Erythema

• Anorexia

• Increased susceptibility to infection

• Fetal Damage in pregnant women


Exposure

• Varies depending on the type and stage of cancer being

treated.

• Typical dose for a solid epithelial tumor ranges from 60 to 80 Gy,

• Lymphoma tumors treated with 20 to 40 Gy.

• Doses are spread out over a period of time (Fractions).

• Allows normal cells time to recover

• Allow tumor cells to develop into a radiation sensitive phase of

the cycle before next fraction.

• Typical fractionation schedule for adults is 1.8 to 2 Gy per day,

five days a week.


Effects on Cancer

• Response based on cancers

radiosensitivity.

• Highly radiosensitive cancer are rapidly killed

my modest doses of radiation. (Leukemia,

lymphomas, and germ cell tumors)

• Epithelial l cancers are moderately

radiosensitive.

• Need higher dose (60-70 Gy)

• Melanoma and Renal cell cancer

• Highly radioresistant


Radiation Therapy Accidents

• 1985-19871987 Radiation therapy machine Therac-

25

• Patients given up to 100 times the intended dose

• 2 people killed

• 2005-20102010

• Missouri hospital overexposed 76 patients during 5yr

period.

• Due to incorrect set up of equipment

• 2009 Los Angeles Hospitals

• 200 patients were exposed to dangerous levels of

radiation during brain scans


Discussion

• Should physicians continue to use radiation

therapy knowing the side effects that are known

and new effects which are being discovered in

the survivors of Hiroshima and Nagasaki?

• Passengers on commercial airliners are

exposed to larger amounts of radiation. Should

the government place restrictions on the number

of hours individuals can fly?

• Should higher quality standards be placed

on the radiation i therapy machines that are being

used in hospitals to prevent patients from being

overexposed to radiation?

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