Unit 4

early effects of radiation

Responses in humans to radiation that occur immediately to within a few days or months from exposure

early effects of radiation

tissue effects

deterministic

non-stochastic reactions

early effects of radiation

nonlinear threshold

early effects of radiation

responses depend on the individual’s radiosensitivity, dose amt, shallow or deep, and dose rate

examples of early effects of radiation

erythema

epilation

cataracts

early effects of radiation

highest when high LET is given in a large dose or to a sensitive area

whole body threshold dose (death)

1 Gy

whole body threshold dose (hematologic depression)

0.25 Gy

skin erythema threshold dose

2 Gy

epilation threshold dose

3 Gy

Death threshold dose is low because hematologic syndrome can occur at 1 gy and can lead to death

why is death threshold so low?

acute radiation syndrome

The sequence of events after high level radiation exposure that leads to death within days, weeks, or months

high doses, acute exposure to whole body

hematologic death

GI death

cerebrovascular death

examples of ARS

those exposed to radiation from Chernobyl, Atomic Bomb survivors, Marshal Islanders, Radiation therapy patients (skin)

shortening of life span

what is the main consequence of ARS?

1. prodromal

2. latent

3. manifest illness

4. recovery/ death

what are the stages of acute radiation lethality

prodromal period

Acute clinical symptoms that occur within hours of exposure and continue up to a day or two

prodromal period

Nausea, vomiting, diarrhea, and a reduction in white blood cells

prodromal period

As dose increases symptom severity increases

latent period

period of “well-being”la

latent period

doses from 1-5 Gy occurs within weeks

latent period

doses exceeding 50 Gy occurs within hours or less

manifest illness

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

Symptoms depend on the specific syndrome

near lethal doses

2-3 Gy

highly lethal dose

more than 6 Gy

hematopoietic effects

bone marrow syndrome

hematologic effects

hematopoietic system

Consists of bone marrow, circulating blood, lymphoid tissue/ organs

stem cells in hematopoietic system

pluripotential stem cells

lymphocytes

granulocytes

thrombocytes

erythrocytes

pluripotential stem cell mature into…

lymphocytes

(WBC are leukocytes – lymphocytes are a subgroup) immune response – defend against disease, produce antibodies

granulocytes

subgroup of WBC, stem cells are neutrophils) - used to fight bacteria

thrombocytes

platelets – clotting of blood to prevent hemorrhage

erythrocytes

RBC – transport agents for oxygen

lymphocytes

produced at varying times, have shortest lifespan of all blood cells around 24 hours

granulocytes

take 8-10 days to be produced, last a couple days

thrombocytes

5 days to produce, last 1 week – 1 month

erythrocytes

8-10 days produced, last 4 months

hematopoietic syndrome dose

1-10 Gy

recovery period for hematopoietic syndrome

3 weeks - 6 months

death period for hematopoietic syndrome

10 - 60 days

cell renewal system

Hematopoietic stem cells (HSCs) are a unique population of cells with the remarkable ability to replenish themselves through self-renewal and to give rise to differentiated cell lineages

Destruction of bone marrow

Inadequate blood cell production

Decrease in:

• Red blood cells

• White blood cells

• Platelets

hematopoietic syndrome is characterized by:

lymphocytes

1st cells to become affected (reduced in number) – occurs within minutes, hours, or up to several months

granulocytes

rapid increase, then rapid decrease, then slower decrease. – occurs within 15-20 days, recovery takes several months

thrombocytes

deplete slowly, reach a minimum in 30 days, recovery takes 2 months

erythrocytes

less sensitive than other blood cells, occurs within several weeks, recovery takes 6 months to a year

0.25 Gy

What is the minimum dose necessary for hematologic depression to occur?

non-linear threshold

What does relationship do early effects follow?

increased chance of infection

What occurs in the body when bone marrow cells are destroyed?

destruction of epithelial cells and villi

GI syndrome is characterized by:

GI syndrome dose

10-50 Gy

death occurs within ….. for GI syndrome

4- 10 days

Damage to cerebrovascular structure within the brain

Damage to blood vessels that supply blood to the brain

• Results in fluid leaking into brain, increased intracranial pressure, tissue damage

cerebrovascular syndrome is characterized by:

cerebrovascular syndrome dose

more than 50 Gy

death occurs when for cerebrovascular syndrome

3 days

cerebrovascular syndrome

Radiation damages endothelial cells and breaks down the blood brain barrier

Causing intracranial pressure (brain swelling), vasculitis (inflammation of vessels), fluid leakage, and meningitis

cerebrovascular syndrome

Ultimate cause of death is elevated fluid in the brain

true

T/F: if GI syndrome is occurring so is hematopoietic syndrome

mean survival time

Average length of time from exposure that half of those exposes are still alive

decreases

As whole-body radiation dose increases, the time between exp and death…

lethal dose (LD)

Way to compare sensitivity of tissues, organs, and species

lethal dose (LD)

LD x/y

• x =  % of population expected to die

• y =  number of days measured

LD 50/30

The dose of radiation to the whole body that causes 50% of the subjects to die within 30 days

LD 50/30

3-4 Gy

LD 50/30

nonlinear threshold

LD 50/60

The dose of radiation to the whole body that causes 50% of the subjects to die within 60 days

LD 50/60

3.5 Gy

William Rollins

Who was the first known advocate for radiation exposure protection due to his own experience with radiation burns?

skin effects

nonlinear threshold response

mild erythema dose

2 Gy

epilation dose

3 Gy

permanent epilation dose

7 Gy+

SED50

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

ringworm

What other skin disease was treated with low kVp x-rays causing hair loss?

radiation therapy

cath lab

IR

Early effects on the skin are more likely to occur from procedures in what 3 advanced imaging modalities?

radiation therapy patients

radiation accident victims

volunteer convicts

What 3 groups of humans have been studied for gonadal response to radiation?

female gonads

oogonia → oocytes → ova

male gonads

spermatogonia → spermatocyte → spermatid → sperm

sterility in females

5-10 Gy

sterility in males

5 Gy

basal cells

what are the stem cells of the skin?

erythema

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

skin erythema dose 50

SED50

2 Gy

what threshold dose causes temporary infertility in both males and females?

Goiania Accident

Brazil 1987

two men stole a radioactive canister from an abandoned hospital

4 deaths

20 cases of ARS

Over 250 highly contaminated

Over 100,000 monitored

Hisashi Ouchi

victim of Tokaimura accident in Tokai, Japan

Poured uranium solution into uranium tank creating nuclear fission chain reaction

Received 17 Gy

Immediate pain, bloody diarrhea, vomiting and loss of consciousness, almost zero WBC count, severe skin burns, skin loss, internal organ/muscle damage

Lived 83 days with multiple resuscitations and blood transfusions against his will

alexander litvinenko

Russian spy who pas poisoned by other spies with radiation

demon core

experiment in New Mexico for the atomic bomb

two scientists: Harry Daghlian and Louis Slotin

plutonium experiments

1940s – 1990s

Manhattan project/US Atomic Weapons Programs/NASA/private and public hospitals

• 18 humans purposefully and unknowingly injected after accidents

• 73 disabled children spoon-fed radioactive oatmeal

• 892 pregnant women given radioactive vitamins

Numerous prisoners' testicles radiated

Radiation sickness, cancers, blood disorders, skin damage