Radiation Biology Final

As an ionizing radiation passes through a cell

damage to the cell may not occur

nucleus

The most radiosensitive structures and/or molecules are found

inhibit mitosis

In addition to its ability to kill cells, ionizing radiation can also

cells which are mitotically active are radiosensitive

The law of bergonie and tribondeau states in part that

primitive or undifferentiated cells are radiosensitive

the law of bergonie and tribondeau also states that

rate of energy deposition

linear energy transfer (LET) is

is greater than particulate radiation

LET

the frequency of their occurrence is increased

although radiation-induced genetic mutations are identical to naturally occurring mutations

increases linearly with the dose of radiation

The frequency of radiation-induced genetic mutations

harmful

most of the radiation-induced mutations are

are permanent

radiation-induced genetic mutations

the dose which produces only one mutation is known

there is no threshold dose known for the induction of mutations. this means that

changes in DNA

radiation-induced mutations are a result of

5-8 years

it is believed that the induction of leukemia follows irradiation by

leukemia

the earliest radiation-induced cancer is thought to be

the rate of mutations increases linearly with age

analysis of the chromosomes in lymphocytes of the peripheral circulation in man suggests that

LET

within limits, mutational frequency is directly proportional to

nonspecific life-span shortening

one (some) of the late effects of radiation on living systems is (are)

decreasing the amount of available oxygen, producing hypoxia

The simplest and most effective means of reducing the biological response to radiation is produced by

are highly radiosensitive

bone marrow and lymphoid organs

very radiosensitive as an exception to the law of bergonie and tribondeau

even though the lymphocyte does not undergo mitosis, it is

may be seen months or years following exposure

the late effects of radiation

unlike other carcinogens, only radiation will produce cancer in all species

ionizing radiation is a universal carcinogen because

spontaneous abortion

irradiation of the embryo with small (diagnostic) amounts of radiation may result in

avoided, especially during the first trimester

in a pregnant female, diagnostic procedures involving the use of ionizing radiation should be

the younger the embryo, the more sensitive

radiosensitivity of the embryo changes with age so that

follow the same metabolic processes as their non-radioactive counterparts

once inside the body, radionuclides

very difficult

calculation of the radiation dose from internally located radionuclides is

alpha and beta emitters dissipate most of their energy within a small volume of tissue within a critical organ

internally located alpha and beta emitters are more hazardous than a gamma emitter because

physical half-life

in calculating the effective half-life, which factors must be considered

an estimate of the rate of removal of the element from the tissue

the biological half-life is

physical properties

in order to handle the radionuclide safely, the tech must know the radionuclides

effects from background radiation

the effects of low doses of medical radiation are very difficult to determine because they may be masked by

no amount of radiation is considered safe

very low doses of radiation from medical procedures are considered safe if they

benefit clearly prevails

in evaluation of risk vs. benefit of medical radiation, usually

patients age

one of the factors that may affect the risk of low-level irradiation in nuclear medicine is

are pure gamma emitters

Patients radiation doses from nuclear medicine procedures can be reduced by use of radionuclides which

have little or no effect on cells, tissues, or organs

at a diagnostic level, ultrasound has shown to be

germ and somatic cells

2 categories of cells in the nucleus are

DNA and RNA

2 examples of radionuclides acids

the nucleus

the most radiosensitive part of the cell is

anabolism

buildup inside the cell

catabolism

destruction that occurs outside of the cell

RBC’s

Mature undifferentiated cells performing the function of oxygen carriers

lymphocytes

Most sensitive to radiation

true

ionizing radiation in more effective against cells that are dividing (T/F)

False

cells which are meiotically active are radiosensitive (T/F)

true

a differentiated cell has a specialized function (T/F)

false

the most radiosensitive period for a fetus is the last trimester (T/F)

true

DNA is considered the primary target for radiation induced cell death (T/F)

false

mitosis is the process by which germ cells divide (T/F)

false

DNA is the least likely target for radiation (T/F)

occurs without external influences and can happen naturally

a spontaneous mutation

mutagenesis

the process of DNA becoming modified is called

carcinogen

promotes the development of cancer

germline and somatic

what are the different types of mutations

a change in a gene that occurs in a parents reproductive cells that affects the genetic makeup of the child

germline mutation

a change in a gene that occurs after conception in developing embryo that may become a baby

somatic mutation

DNA bonds and breaks them

when radiation its directly, it affects the

the water molecule surrounding the DNA

when radiation hits indirectly, it affects

there is a defect in the number of chromosomes in a cell of an organisms or in the arrangement of genetic material

chromosome and chromatid abnormalities occur when

23 pairs for a total of 46

how many chromosomes are in a human cell

at or above approximately 0.5 Gy (50 rads)

acute radiation effects

cancer formation and cataracts

chronic effects of radiation

500-800 R

radiation dose directed at the lens of the eye that causes cataracts

50 rads or more

radiation sickness seen in man following whole body exposure at

division delay, reproductive failure, interphase death

3 ways for cellular injury to occur after ionizing radiation exposure

50rads (0.5gy) up to 300rads (3gy)

division delay is seen in doses greater than

anxiety with tachycardia, n/v, diarrhea

the earliest clinical manifestations resulting from whole-body exposure to a large dose of radiation are

Lethal dose of radiation expected to cause death to 50% of the exposed population within 30 days.

LD50/30

400- 450rem (250-450rad) received over a short period of time

LD50/30 dose

average dose to an average individual is 100mrem

gonadal dose

means random in nature, any random occurrence of a disease that can not be attributed solely to radiation

stochastic

stochastic in nature

heredity effects and carcinogenesis are considered to be

little to no effect on cells, tissues, or organs.

ultrasound has

normal attenuation process, it results in gas bubbles present in all fluids. This is used a 1-15MHz

cavitation

bone marrow syndrome occurs when bone marrow is severely damaged by radiation exposure. Radiation dose between 1-8gy (100-800 rad)

hematopoietic syndrome

with increasing radiation dose. Death usually occurs due to complications like infection and hemorrhage, typically between 10 and 30 days after irradiation

The survival rate of individuals with the hematopoietic syndrome decreases with

a serious complication of high dose radiation exposure, typically occurring with doses above 10gy (100rads)

gastrointestinal syndrome

GI death occurs in an individual who dies in 3 to 10 days following an acute whole-body exposure.

GI death

Experiences anorexia, Develops dehydration secondary to Nausea and vomiting, May show signs of infection due to almost total depletion of WBcs

In a true GI syndrome the patient

prodromal, incubation, onset, convalescent

acute radiation syndrome phases

very high doses of radiation, typically 50 Gy or higher, that can result in death within 1-3 days.

Central Nervous System syndrome is a form of acute radiation syndrome caused

causes edema, meningitis, vasculitis

CNS mechanism

n/v, diarrhea, disorientation, impaired balance, neurological effects

CNA syndrome symptoms

occurs within a few hours following 10,000 rads or more of whole body exposure

CNS death

lesions of the lungs

what is cns death associated with

because changes in this organ may not be apparent, it happened to quickly

why would a patient dying from CNS syndrome show an undamaged and intact gut because