Transcript EARLY EFFECTS OF - Montgomery College
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 • Survive a few weeks • 1000-10,000 rads • 3-4 days • 10,000 + • few minutes
FOUR STAGES TOTAL 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 • Bone Marrow B) Gastrointestinal C) Cardiovascular D) Cerebrovascular/ CNS
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
• 10 rad • 200-250 rads
TESTES
effect?
effect?
• 500-600 rads effect?
OVARIES
• 10 rad • more sensitive in fetus /small children • 200 rad • 500-625 rads effect?
why?
effect?
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 • Cytogenetic • Not!!!
• D) a chromosome aberration • Correct answer. Used for cytogenetic analysis • Structural damage
To Be continued
• See power point entitled Chapter 8