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