Unit 4 - Rad Bio

early effects of radiation

responses in humans to radiation that occur immediately to w/in a few days or months from exposure

deterministic/non-stochastic/tissue reactions

non-linear threshold

radiosensitivty, dose amount, shallow or deep, dose rate

what does the early effects of individual reponses depend on?

whole body

1 Gy

what is the minimum threshold & anatomical site for the effect of death?

whole body

0.25 Gy

what is the minimum threshold & anatomical site for the effect of hematologic depression?

small field

2 Gy

what is the minimum threshold & anatomical site for the effect of skin erythema?

small field

3 Gy

what is the minimum threshold & anatomical site for the effect of epliation?

acute radiation syndrome (ARS)

sequences of events after high level radiation exposure that leads to death w/in days, weeks & months

hematologic death

gastrointestinal (GI) death

cerebrovascular/CNS death

what are the high dose of acute radiation exposure to the whole body results?

prodromal period

acute clinical symptoms that occur w/in hours of exposure & continue up to a day or two

includes raidation sickness effects

nausea, vomitting, diarrhea & reduction in white blood cells

what are the effects of radiation sickness?

severity increase

w/in the prodromal period, as the dose increase, what happens?

latent period

period of “apparent” well-being

doses from 1-5 Gy occurs w/in a week

doses exceeding 50 Gy occurs w/in hours or less

manifest illness

reveals the full, specific organ system damage caused by the radiation

symptoms depend on specific syndrome

hematopoietic

gastrointestinal

cerebrovascular

what are the three symptoms of manifest illness?

2-3 Gy

what is the near lethal dose?

near lethal dose

symptoms are less severe

recovery may occur months to years

highly lethal doses

death occurs in days or weeks

greater than 6 Gy

what is the highly lethal doses?

hematopoietic system

consists of bone marrowing, circulating blood & lymphoid tissue/organs

all cells develop from same type of stem cell

these cells develop at different rates in bone marrow & released in the peripheral blood as mature cells

pluripotential

what is the type of stem cells that the hematopoietic system develop from?

lymphocytes

granulocytes

thrombocytes

erythrocytes

what are the different types of mature cells that can be developed by the hematopoietic system?

lymphocytes

producing at varying times

has shortest lifespan of all blood cellsgr

granulocytes

take 8-10 days to be produced

last a couple of days

thrombocytes

5 days to produce

last 1 week to 1 month

erythrocytes

8-10 days to produce

last 4 months

1-10 Gy

what is the approx dose of hematopoietic syndrome?

mild sickness

what is the effects during the prodromal period of hematopoietic syndrome?

wellness up to 4 weeks

what is the effects during the latent period of hematopoietic syndrome?

nausea, vomitting, diarrhea, malaise, fever, infection

what is the manifest illness effects of hematopoietic syndrome?

recovery begins in 3 weeks

can take about 6 months for full recovery

bone marrow cells can repopulate through a cell renewal system

what happens if the hematopoietic syndrome dose is not lethal?

reduction in blood cells continues until the body has no defense aganist infection

before death = hemorrhage & dehydration

death w/in 10-60 days

what happens if the hematopoietic syndrome dose is lethal?

hematopoietic characterization

destruction of bone marrow

inadequate blood cell production

decrease in red & white blood cells & platelets

lymphocytes hematopoietic reponse to raidiation

1st cell to become affected

occurs w/in mins, hours or up to several months

granulocytes hematopoietic reponse to raidiation

rapid increase → rapid decrease → slower decrease

occurs w/in 15-20 days

recovery takes several months

thrombrocytes hematopoietic reponse to raidiation

deplete slowly

reach a minimum in 30 days

recovery 2 months

erythrocytes hematopoietic reponse to raidiation

less senstitive then other blood cells

occurs w/in several weeks

recovery = 6 months to a year

lymphocytes & spermatogonia

what are the most radiosensitive cells in the body?

gastrointestinal characterizations

destruction of epithelial cells

small bowel

what is the most sensitive part of the GI tract?

10-50 Gy

but can occur as early as 6 Gy

what is the dose approx for gastrointestinal syndrome?

nausea, vomitting, diarrhea

what is the prodomal peroid effects of gastrointestinal syndrome?

3-5 days of wellness

what is the latent period effects of gastrointestinal syndrome?

2nd wave of nausea, vomiting, diarrhea w/ loss of appetite, lethargy & shock

rapid progression of symptoms

death occurs w/in 4-10 days

dose exceeds threshold = hematologic syndrome also occurring

what is the manifest illness effects of gastrointestinal syndrome?

minimal shortening & sloughing of villi

what happens to the small intestine after 5 Gy of raidation?

blunt villi

atypical epithelial cells

what happens to the small intestine after 10 Gy of raidation?

absence of crytps

sloughing of edma & villi

atypical epithelial cells

what happens to the small intestine after 20 Gy of raidation?

cerebrovascular characterization

damage to cerebrovascular strcuture w/in the brain

damage to blood vessels that supply blood to brain

results in fluid leaking into brain

increases intracranial pressure & tissue damage

what happens when fluid leaks into the brain?

greater than 50 Gy

what is dose for cerebrovascular syndrome?

severe nausea, vomiting, diarrhea

what is the prodomal period effects of cerebrovascular syndrome?

can last up to 12 hours

what is the latent period effects of cerebrovascular syndrome?

prodromal symptoms return more severly

includes disorientation, loss of muscle coordination, seizures, lethary & coma

what is the manifest illness effects of cerebrovascular syndrome?

cerebrovascular syndrome

death w/in 3 days of exposure

raidation damages endothelial cells & breaks down the blood-brain barrier

causes intracranial pressure, vasculitis (inflammation of the vessels)

all other organs are damaged severely

isn’t enough time between exposure & death

why is there no occurrance of hematopoietic or GI effects during the cerebrovascular syndrome?

mean survival time

average length of time from exposure that half of the those exposure are still alive

as whole body raidation dose increases, time between exposure & death decreases

decrease in latent period & time until death

if the dose increases, what happens according to the mean survival time?

2-8 weeks

what is the survival time for hematoloic syndrome w/ the dose of 1-10 Gy?

3-10 days

what is the survival time for GI syndrome w/ the dose of 6-50 Gy?

0-3 days

what is the survival time for cerebrovascular syndrome w/ the dose of greater than 50 Gy?

lethal dose (LD)

way to compare sensitivity of tissues, organs & specific

LD = X/Y

x → % of population expected to die

y → # of days measured

what is the lethal dose formula?

LD 50/30

the dose of radiation to the whole body that causes 50% of the subjects to die w/in 30 days

considered to be about 3-4 Gy

non-linear threshold

LD 50/60

the dose of radiation to the whole body that causes 50% of subjects to die w/in 60 days

more accurate & meaningful for humans

considered by 3.5 Gy

10/30

100/60

what are other lethal dose quoted examples?

william rollings

first known adovcate for radiation exposure protection due to own experience w/ radiation burns

skin

consist of 3 layers & accessory structures

epidermis consists of several layers containing skin stem cells

basal layer

what is the lowest layer of the skin?

early mainfestation of injury

what happens if there is damage to the skin’s stem cells?

skin/local effects

non-linear threshold repsonse → 2 Gy

mild erythema occurs w/in 1-2 days

2nd wave w/ max intensity in about 1-2 weeks

shedding of the outer layer of skin

what is desquamation?

hair loss

what is epilation?

clinical tolerance from rad therapy

what causes moist desquamation?

3 Gy

what is the dose for temporary epilaion?

7 Gy or higher

what is the dose for permanent epilation?

erythema

1st observed biological response to radiation exposure (due to short SSD)

SED 50 (skin erythema dose)

dose required to produce erythema 50% of those irradiated is approx 5 Gy

ringworm

what is a skin disease is treated using low kVp?

rad therarpy

cardiovascular lab

interventional rad

where are early skin effect most likely to occur?

rad therapy pts

rad accident victims

volunteer convicts

how is gonadal effect studied?

gondal cells

produce germ (reproductive) cells that control fertility & heredity

gametogenesis

the process of overies & testes producing oogonia & spermatogonia which mature into ovum & sperm

2 Gy

what is the temporary infertility dose for both genders?

5-10 Gy

what is the permanent sterility dose for females?

5 Gy

what is the permanent sterility dose for males?

female gonads

before birth, oogonia multiply to reach several million & begin to decrease

oocytes reamin inactive until puberty w/ reducing numbers

after puberty, oocytes mature into ova

only about 400-500 are ever available for fertilization

before puberty

when are female most radiosensitive?

male gonads

always radiosensitive

spermatogenia are continually being produced from stem cells

spermatogenia mature into spermatocytes, which develop into spermatids

spermatid matures into sperm → process = 3-5 weeks

goiania accident

brazil 1987

4 deaths

20 causes of ARS

over 250 highly contaminated

over 100,000 monitored

tokaimura accident

Hisashi Ouchi

poured uranium solution into uranium tank creating a nuclear fission chair reaction

recieved 17 Gy = hemapoietic & GI effects

lived 83 days w/ multiple resusations & blood transfusions aganist his will

alexander litvinenko

spy posioned by drinking plutonium in tea

plutonium experiments

18 human unknowingly injected after accidents

73 disabled children spoon fed radioactive oatmeal

892 pregnant women given radioactive vitamins

derministic/non-stochastic

predictable

only occurs at specific dose thresholds -> minimum dose threshold is reached

affect specific tissues

have known threshold doses for results of effects

severity of the illness depends on the dose