Late Effects Of Radiation

1
Late Effects Of Radiation

• Kyle Thornton
• RADL 70

2
Long Term Effects

• Malignant disease
• Local tissue damage
• Life-span shortening
• Genetic damage
• Potential effects to fetus

3
Modern Radiation Incidents

• Three Mile Island
• U.S 1979
• Chernobyl
• USSR 1986

4
Three Mile Island

• App. 10 MCi of Xenon-133 released into atmosphere
• App. 15 Mci of Iodine-131
• Translates to
• 8 mrem over 10 miles
• 2 mrem over 50 miles

• Expectations
• App. .7 additional cancer deaths/2 million people
  living in that region
• Anti-nuclear backlash caused increase in
  coal-generated electricity

5
Chernobyl

• Tons of uranium dioxide released into atmosphere
• Cesium 137
• Iodine 131
• 203 out of 444 workers suffered ARS
• Most were 25 - 35

• Many individuals in the 400-600 rem dose category
  survived
• Bone marrow transplants were helpful

6
Incidence Of Leukemia Due To Radiation Exposure

• First case of skin cancer due to radiation
  exposure in 1902
• 1911 - First noted case of radiation induced
  leukemia
• Increased incidence of leukemia in atomic bomb
  survivors

7
Bone Cancer

• Radium dial painters
• Ingested radium
• Radium deposited in bones
• Increased incidence of osteogenic sarcoma and
  osteoporosis
• Radon is very high LET radiation
• Alpha and Beta particles emitted

8
Radiologic Technologists And Occupational Exposure

• 104,000 technologists studied
• Cancer found in 3/6 of respondents
• 9 observable birth defects
• 98 wore monitors/ 95 wore lead aprons
• 10 radiographed each other during training
• Technologists found more likely to use radiologic
  services than general public
• Increases overall dose

9
Radon Exposure

• High indoor levels of radon in houses
• Active or passive exposure to cigarette smoking
• EPA attributes 5000 - 20,000 lung cancer deaths
  due to radon/year

10
Thyroid Cancer

• Children treated for for thymus hypertrophy
  experienced higher incidence in thyroid cancer
• Children treated for ringworm showed higher
  incidence in thyroid cancer
• Thyroid follows linear, nonthreshold
  dose-response relationship

11
Studies Showing Evidence Of Carcinogenesis In
Humans

• Atomic Bomb Survivors
• Leukemia, Thyroid, Breast
• Marshall Islanders
• Some thyroid cancer
• Radium Dial Painters
• Bone cancer
• Early Radiologists
• Leukemia, skin cancer
• Multiple Chest Fluoroscopy
• Breast cancer

• Infants W/Enlarged Thymus
• Thyroid cancer
• Thorotrast
• Leukemia, Liver cancer
• In Utero Exposures
• Leukemia
• Iodine 131 Therapy ForThyroid
• Some leukemia
• Uranium Miners
• Lung cancer

12
Conclusions About Radiation-Induced Cancer

• Single exposure can be enough to elevate cancer
  incidence several years later
• There is no radiounique cancer
• Almost all cancers are associated with radiation
• Breast, bone marrow, and thyroid are especially
  radiosensitive
• The most prominent radiogenic tumor is leukemia
• Solid tumors have a latent period of 10 years

• Leukemias latent period is thought to be about 5
  - 7 years
• Age of irradiated individual is most important
  factor
• Percentage increase in cancer incidence/rad
  varies between organs and types of cancers
• Dose-effect curves are best assumed to be linear

13
Skin

• Highly vascular organ
• Basal layer is constantly regenerating
• Most radiosensitive layer
• Late changes in skin
• sunburn, aging
• atrophy
• fibrosis
• change in pigmentation
• ulceration
• necrosis

14
Eyes

• Cataractogenesis
• Latent period may take up to 30 years
• Thought to be threshold, non-linear response
• About 200 rads
• All will develop cataracts at 1000 rads

15
Digestive System

• Small bowel is the most radiosensitive organs of
  the digestive system
• 500 rads
• atrophy, strictures, fibrosis, ulceration
• 1000 rads
• Permanently destroy villi
• ulceration, fibrosis, necrosis

16
Urinary System

• Considered radioresistant
• 2500 rads can lead to renal failure

17
Growing Bone And Cartilage

• 100 rads
• Temporary halt in mitosis of developing bone
  cells
• 1000 rads
• Permanent suppression of mitosis
• Severe impact on both size and shape of bones in
  adulthood

18
Central Nervous System

• Considered radioresistant
• no known effects below 1000 rads

19
Cytogenetic damage

• Increased spontaneous abortions or still birth
• Altered sex ratios
• Leukemia and other neoplasms
• Increased infant mortality
• Increased congenital effects

• Decreased life expectancy
• Dominant inherited diseases
• Dwarfism, Polydactly, Huntingtons Chorea
• Recessive inherited diseases
• Cystic fibrosis, Tay-Sachs, hemophilia, albinism

20
Doubling Dose

• Dose of radiation that will produce twice the
  frequency of genetic mutations than without
  radiation exposure
• Mutations occur in nature with certain frequency

21
Genetically Significant Dose

• The dose equivalent to the reproductive organs
  that would bring about genetic injury to the
  population if received by the total population
• The estimated GSD for the US is about 20 mrem

22
Radiation Effects On Fetal Development

• Three basic stages in development
• Preimplantation
• Conception to 10 days post conception
• Organogenesis
• Cells implanted in uterine wall
• Cells begin differentiating into organs
• Fetal or growth stage
• Sixth week after conception
• Growth rather than new development

23
Principle Effects Of Radiation On Embryo Or Fetus

• Embryonic or fetal death
• Malformations
• Growth retardation
• Congenital defects
• Cancer induction

24
10 - 25 Rule

• Doses of less than 10 rad
• No indication to terminate a pregnancy
• Doses between 10 and 25 rad
• Gray area for terminating pregnancy
• Doses above 25 rad
• Termination should be considered

25
Radiation Damage In Terms Of When Irradiated

• Cataracts
• 0-6 gestation days
• Herniation of the brain
• 0 - 37 days
• Embryonic death
• 4 - 11 days
• Anencephaly or microcephaly
• 9 - 90 days

• Anophthalmia
• 16 - 32 days
• Cleft palate
• 20 - 37 days
• Skeletal disorders
• 25 - 85 days
• Growth disorders
• 54

26
Doses To Embryo Per Procedure

• Based on overhead films only
• Average number of films/examination
• Barium Enema - 800 mrad
• Cholecystrogram - 80 mrad
• IVP - 800 mrad
• Pelvis - 200 mrad
• UGI - 50 mrad