Radiation Biology - Late Effects (RADS 349)

Long or late term effects

cumulative or single exposure causing biologicsal response greater than 6 months

Low dose (terms of dose)

100 rads or 1 Gya

Moderate dose (terms of dose)

100 - 1000 rads or 1 - 10 Gya

High dose (terms of dose)

greater than 1000 rads or 10 Gya

Radiation induced lifespan is...

nonspecific

Humans can expect to reduce life span by...

10 days for every rad or 0.1 Gya they recieve

Life span shortening in humans has not been totally accepted because of what 3 studies?

-Atomic Bomb Survivors - no life span shortening

-Radium Dial Painters - no life span shortening

-R.T.'s from WW2, who use field of x-ray equipment - no life span shortening

-X-ray pt's - no life span shortening

High dose causes changes in pigmentation of skin ex.

-a hypo condition (light spots)

-a hyer condition (dark spots)

-or both

-a weather appearance, crack and flaking skin

Low and moderate dose to skin (late effects)

no late effects on skin

Late Effects - Chromosmes

if exposed in circulating blood it causes chromosome damage to the lymphocytes and may lead to leukemia

Cataracts

an increased opacity of the lens of the eyes (becomes cloudy)

-late effect of the lens of the eye

Latent Period for Cataracts - Lens of the Eye

avg. 15 years, range of 5 - 30 years, shorter if the individual is older

Cataracts were first noticed in...

cyclotron physicists

When it comes to the lens of the eye at high doses 100% of pt's will develop...

cataracts and the older the individual the greater the radiation effects

Late Effects - DIgestive System

None are reported

-studied up to 7000 rads or 70 Gya

Heart - Late Effects

only affected by high doses

-at 4000 rads or 40 Gya produces pericarditis

Blood Vessles - Late Effects

at moderate and high doses, thrombosis and/or sclerosis will occur

-smaller the blood vessles, the more radiosensitive it is

Mature Bones are almost...

completely radioresistant, no late effects

At high doses more than 2000 rads or 20 Gya (Late Effects - Growing Bones)

there will be permanent mitotic loss altering size and shape

At moderate doses of radiation growing bones will have...

division delay

High doses results in... (Late Effects - Hepatic Cells)

improper bile production, while low and moderate doses nothing will occur

High doses results in... (Late Effects - Liver)

ascites and hepatic enlargement, or hepatitis, while low and moderate doses nothing will occur

Doses more than 1000 rads or 10 Gya may produce... (Late Effects - Lungs)

Pneumonia

Doses more than 1000 rads or 10 Gya may produce ______________; while a specific dose of 2800 or 28 Gya over 5 weeks causes ____________ (Late Effects - Kidneys)

radiation nephritis; FATAL radiation nephritis

Studies of major events such as Chernobyl and Hiroshima proves to us that... (Radiation Induced Malignancy)

there is an increased cancer risk from high dose radiation exposure

Leukemia (Radiation Induced Malignancy)

incident of this increases with increasing dose

-studies of this on RT's showed no evidence of this, but studies on radiation therapy patients who were treated for Anklosing Spondylitis showed incidents of leukemia

The effects of Leukemia were _________ times greater 7 years following the Chernobyl accident with a latent period of __________

1.2; 5-7 years

Groups that had Neoplasms of the Thyroid Cancer from radiation exposure (Late Effects - Thyroid Cancer)

-Ann Arbor & Rochester Group (Children)

-Children in Rongelap Atoll (Marshall Islands)

-Radiation Therapy for Tinea Capitis

-Chernobyl (6000 cases in children)

Chief Health issues of the Chernobyl Accident

Leukemia & Cataracts

Two groups linked to Bone Cancer

- Radium Dial Painters

- Patients who were trated with radium for arthritis and tuberculosis

Radium Dial Painters (Radium girls)

ingested radium and it behaves like calcium

-deposits in the bone leading to a very high risk of bone cancer (122:1)

Two groups linked to Skin Cancer

-Early Radiologists

-Radiation Therapy Patients who were treated with Orthrovoltage

Latent Period for Skin Cancer

5-10 years

Relative risk of developing skin cancer for 500-2000 rads or 5-20 Gya is ________, while the relative risk of deloping skin cancer for 6000-10000 rads or 60-100 Gya is _______

4:1; 27:1

-the higher the dose of radiation the higher the risk of getting skin cancer

Two groups linked to Breast Cancer from radiation

-Tuberculosis Patients

-Patients who were treated for post-partum mastitis with x-rays

Tuberculosis Patients were treated in...

sanitariums, using fluoro to iduce artificial pneumothorax to allow the lung to heal

Groups linked to Lung Cancer from radiation

- 50% of Bohemian Pitchblende Miners (died)

- American Uranium Miners

Pitchblende

ore of uranium

As uranium decays it becomes...

radon 222 a gas of alpha radiation that the american miners would inhale leading to lung cancer

Relative risk for Lung Cancer increased for American Uranium Miners if they...

were smokers

-normal - 8:1, smoking - 20:1

What leads to Liver Cancer when it comes to radiation?

Thorostrast was a widely used contrast meadia that was radioactive

-linked to several types of cancers but expeciallt this one

-latent period of 15-20 years

Most radiosensitve stage in life of any organism...

Embryo because cells are rapidly dividing and just starting to be differentiated (making it more sensitive)

Pre-implantation

when fertilized egg is passing through the fallopian tube and has not implanted yet (8-10 days)

Major organogenesis

when the major organs of the body are being completed (2nd-8th wk)

Fetus

when the organs are being completed

Radiosensitivity related to stages of pregnancy:

1st stage - most radiosensitive, then 2nd, then 3rd

Exposure during the early stages, what is the most radiosensitive?

The CNS because neurons are rapidly dividing and are undifferentiated

-this is the oppositite of adults (would be more radioresistant)

The CNS during the pre-implantation stage has show effects in doses as low as...

25 R or 0.02 Gya

Exposure during the pre-implantation stage usually results in...

death at high doses

Exposure during major organogenesis produces...

congenital defects or nronatal death such as anecephaly, hydrocephalus, microcephaly

Exposure during the fetal or final stage results in...

functional defects (dwafism, cancer) at moderate and high doses

Long Term Genetic Effects

affect future offspring, occuring when radiation striked the sperm or egg cells

the more common genetic effect is

an increase in mutation rate specifically DNA mutation, Gene mutation, Chromosome mutation

if the irradiated egg or sperm cell is later used in conception

the mutation are reproduced billions of times

Observable Genetic Effects include (only at high and moderate doses)

Sex Ratio, more females than males

Leukemia

Down Syndrome

It is belives that both male and female would have...

the same genetic mutation to produce an observable effect