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 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 Gastrointestinal Cardiovascular Cerebrovascular/ CNS Bone Marrow

A) HEMATOLOGIC Death due to dehydration, electrolyte imbalance 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 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? 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