Will Radiographic Exposures 1 Early Tissue Reactions and their effects on Organ Systems (copy)

Which effect is the biologic effects of radiation that occur relatively soon after humans receive high doses of ionizing radiation?

Early effects

Early tissue reactions appear within what after the time of radiation exposure?

Minutes, hours, days, or weeks

With the exception of certain lengthy high dose rate procedures, diagnostic imaging examinations do not usually what?

Do not usually impose radiation doses sufficient to cause early tissue reactions

What are some examples of early tissue reactions?

Nausea, fatigue, erythema, epilation, etc.

What whole body dose can result in many of the manifestations or organic damage occurring in succession?

6 Gy

What is acute radiation syndrome (ARS)?

Radiation sickness

What are the four major stages of Acute Radiation Syndrome?

Prodromal stage, latent period, manifest illness, recovery/death

What are the 3 separate syndromes that occur with total body acute radiation syndrome?

Hematopoietic, gastrointestinal, and cerebrovascular syndrome

The hematopoietic syndrome has a dose range of what?

1-10 Gy

The gastrointestinal syndrome has a dose range of what?

6-10 Gy

The cerebrovascular syndrome has a dose range of what?

50 Gy or more

What does LD stand for?

Lethal dose

What does LD 50/30 signify?

The whole body dose of radiation that can be lethal to 50% of the exposed population within 30 days

What is the lethal dose of radiation for an adult human?

3-4 Gy

What are some examples of measurable late biologic damage?

Cataracts, leukemia, and genetic mutations

What are the outcomes of long-term radiation exposures called?

Late effects

What does threshold mean?

Point at which a response or reaction to an increasing stimulation first occurs

Referring to ionizing radiation, what does threshold mean?

Below a certain radiation level or dose, no biologic effects are observed

Nonthreshold indicates what?

Radiation absorbed dose of any magnitude has the capability of producing a biologic effect

When living organisms that have been exposed to radiation sustain biologic damage, the effects of this exposure are classified as what effect?

Somatic effects

Somatic effects can be subdivided into what?

Stochastic effects and tissue reactions

What does stochastic effect mean?

The probability that the effect happens depends on the dose received

What does tissue reactions mean?

The probability that the effect happens and the severity depends on the dose received

What are late somatic effects?

Consequences of radiation exposure that appear months or years afterwards

Late somatic effects may result from what?

Previous whole or partial body acute exposure, previous high radiation doses, or long-term low doses over several years

What are the 3 categories of adverse health consequences that require study at low levels of exposures?

Cancer induction, damage to the unborn from irradiation in utero, and genetic (hereditary) effects

What are the major types of late effects?

Carcinogenesis, cataractogenesis, embryologic effects

What is the most important late stochastic effect caused by exposure to ionizing radiation?

Cancer

There is a high probability that a single dose of approximately 2 Gy will induce what in the eyes?

The formation of cataracts

Radiation-induced cataracts follow what dose response relationship?

Threshold, nonlinear

What are the stages in gestation?

Preimplantation, organogenesis, and fetal stage

Radiation-induced hereditary effects in humans has what?

Not been demonstrated

What are the causes for genetic mutation?

Radiation-induced damage to the DNA molecule in sperm or ova, natural spontaneous mutations, and resultant genetic disorders or disease