EARLY NONSTOCHASTIC EFFECTS/LATE STOCHASTIC EFFECTS Sherer Chapter 6, Reference: Bushong, Chapter 36 and 37
EARLY NONSTOCHASTIC EFFECTS/LATE STOCHASTIC
EFFECTS
Sherer Chapter 6,
Reference: Bushong, Chapter 36 and 37
Review of Dose response curves
• Threshold
• Non threshold
• Linear quadratic non threshold curve
• Non linear (s-shaped or sigmoid)
Early, Nonstochastic Effects:
• Soon after Rad. Exposure
• minutes• hours• days• weeks• “x-ray burns”
ACUTE RADIATION SYNDROMES
• Total body exposure
• acute exposure in a matter of minutes• 100’s or 1000’s of rads
RADIATION AND MAMMALS
• 200-1000 rads
• 1000-10,000 rads
• 10,000 +
• Survive a few weeks
• 3-4 days
• few minutes
FOUR STAGESTOTAL BODY IRRADIATION
1) PRODROMAL (NVD SYNDROME)
2)LATENT
3) MANIFEST ILLNESS
4) RECOVERY OR DEATH
1)Prodromal
• Initial
• can occur as low as 100 rads
• within minutes with exposure to 1000 rads
• nausea, vomiting, diarrhea (NVD)
2) Latent period
• Weeks in low dose
• Hours in high dose
• pt appears symptom free
• lethal effects or recovery is beginning
3) Manifest Illness
A) Hematologic
B) Gastrointestinal
C) Cardiovascular
D) Cerebrovascular/
CNS
• Bone Marrow
A) HEMATOLOGIC
• AKA: bone marrow or hemotopoietic syndrome
• Rad exposure-low
• Stages:
• Prodromal (NVD)
• Latent
Mitotic stem cells are sterilized
pancytopenia-diminished supply of blood cells
Death due to dehydration,
electrolyte imbalance
infection
B) GI syndrome
• 600 rads(6 gy)-1000 rads (10 gy)
• prodromal - one day
• latent 3-5 days-deterioration of the lining of the GI tract has begun
• manifest of illness
• death ( dehydration, anorexia ) 3-4 days
• cannot prevent progression of syndrome
CARDIOVASCULAR
• Not a syndrome
• Decreased BP
• Increased pulse rate
• Acute myocardial insufficiency
C) Cerebrovascular/CNS
• 5000 RADS
• Prodromal (nausea and vomiting)
• latent period 6-12 hours
• Death occurs within hours- to several days
• GI and Hemopoietic syndrome occurring simultaneously
L/D
• LD 50/30 (Sherer), LD 50/60 (Bushong)– used in animals– humans tend to survive longer (Chernobyl) – see curve (figure 36-1) on page 519 of Bushong
or LD curve on page 120 Sherer
REPAIR?
• Can occur with sublethal doses but dependent on cell or organ’s potential for recovery.
• 10% of radiation induced damage - irreparable
LOCAL TISSUE DAMAGE
• High doses
• atrophy of organ
• Skin-many x-ray pioneers suffered x-ray burns to skin
Skin layers
• Subcutaneous• middle layer• outer layer (epidermis)• accessory structures
– sensory
– hair
– sebaceous
– sweat
Erythema
• 100-300 rad - mild within 1-2 days• Q:Dose Response curve?• A: Non-linear, threshold• Hair loss –epilation• Q:Dose Response curve?• A: For high dose - Non-linear, threshold• low dose – linear, threshold• severe necrosis rare
Late somatic effects
Months or years after whole or partial ARS
OR
Low doses sustained over a couple of years
WHAT ARE THE THREE MAJOR TYPES OF LATE SOMATIC
EFFECTS?
RISK ESTIMATES
• Low doses (below 10 rem) effect must be estimated
• Risk still exists –controversial concept• Absolute risk –specific # of excess cancers
will result due to exposure• Relative risk - # of excess cancers will
increase as the natural incidence of cancer increases in the population with age
Carcinogenesis
• Distinguishing radiation induced cancer from low doses difficult. Why?
• Epidemiologic studies from high doses are used. Examples include:– Radium watch dial painters– Uranium miners– Early Radiation workers – Infants treated with radiation for enlarged thymus– Children of Marshall Island– Japanese atomic bomb survivors– Evacuees from Chernobyl
Match the pathology (can use more than once)
• Radium dial workers• Uranium miners• Early Medical radiation
workers• Infants treated for
enlarged thymus• Children of Marshall
Islands• Japanese atomic bomb
survivors• Chernobyl
• Thyroid• Leukemia• Breast cancer• Bone cancer• Skin cancer• Lung cancer
EXTREMITIES
• Amputations
• radiodermatitis
• shoe fluoroscopy
• nuc med. techs
• LIFE SPAN SHORTENING
• CATARCTOGENESIS
• GENETIC EFFECTS
American RT’s
• Ongoing study of 146,000 RT’s
• Higher risk of dying?
• Higher risk of dying from leukemia?
• Higher risk of dying from breast cancer?
• When did these risks become less?
GONADS
• Highly sensitive• can pass on effects to
future generations• animal
studies/radiotherapy patients, radiation accident victims, convicts
• oogonia• spermatogonia
TESTES
• 10 rad effect?
• 200-250 rads effect?
• 500-600 rads effect?
OVARIES
• 10 rad effect?• more sensitive in fetus/small children why?• 200 rad effect?• 500-625 rads compare this
range with males why the difference?
A karyotype is
• A) study of the genetics of cells
• B) a new type of karaoke machine
• C) a chromosome map
• D) a chromosome aberration
• Cytogenetic
• Not!!!
• Correct answer. Used for cytogenetic analysis
• Structural damage
To Be continued
• See power point entitled Chapter 8