Exposure Exam 1

when were x-rays discovered?

December 8, 1895

the first radiograph produced by dr. roentgen was of ____.

his wife’s hand

who brought attention to the dangers of x-rays?

thomas edison

mass, length, and time are considered ____ quantities.

fundamental

velocity, acceleration, and work are considered ___ quantities.

derived

exposure, dose, and dose equivalent are considered ____ quantities.

radiologic

what is the british system unit for mass?

pound

what is the british system unit for length?

foot

what is the british system unit for time?

second

what is the SI System unit for mass?

kilogram

what is the SI System unit for length?

meter

what is the SI System unit for time?

second

meters per second square is the unit measure of ___.

acceleration

what is the unit measure of force?

newton

kilograms-meters per second (kg-m/s) is the unit measure of ___.

momentum

joule is the unit of measure of __.

work

the property of an object with mass that resists a change in its state of motion

inertia

the ability to do work

energy

energy in a stored state

potential energy

list 4 different types of energy (not including KE or PE)

electromagnetic, electrical, chemical, and thermal

E=MC^2 demonstrates the relationship between what two properties?

mass and energy

what is the standard radiologic unit that quantifies radiation intensity?

C/kg

what is the standard radiologic unit that quantifies the biological effect of radiation on humans and animals?

mSv

what is the standard radiologic unit that quantifies occupational exposure or dose equivalent?

Sv

the ____ is the SI equivalent to the rad.

gray

1 rad = ___ Gy

0\.01

1 rem = ___ Sv

0\.01

The ___ is the SI equivalent to the rem.

Sv

1 R = ____ C/kg

2\.58x10^-4

an expression of the relative risk to humans of exposure to ionizing radiation

effective dose

the positive electrode of the x-ray tube

anode

where is the anode located?

over the right end of the table (caudal)

the negative electrode of the x-ray tube

cathode

where is the cathode located?

over the left end of the table (cephalic)

what is the x-ray tube housing filled with?

lead lining

what is the device that restricts the x-ray beam to the area of interest?

collimator

what is the purpose of the mirror inside the collimator?

to reflect the light

what principle articulates the radiographer’s responsibility to minimize radiation exposure to the patient, oneself, and others?

ALARA

what conditions must exist for x-rays to be produced?

source of electrons, deceleration, acceleration

what are the basic parts of a cathode assembly?

filaments, source of electrons, focusing cups, negative end of tube

what is the purpose of the focusing cup?

focuses electrons as a cloud via electrostatic repulsion

what is the space charge effect?

limit on how many electrons can be produced

why is tungsten the best metal for the x-ray source?

high melting point, high atomic number

what is the line-focus principle?

describes the relationship between the actual and effective focal spots

how does the anode heel effect affect radiation intensity?

the angle effects the effective focal spot and absorbs some of the electrons so the beam isn’t as intense

what is the advantage of a high-speed rotor?

promotes heat dissipation

why is it necessary for a vacuum to exist within the envelope?

lets electrons travel from cathode to anode without interacting with gas atoms/air

define leakage radiation.

radiation from x-ray tube that does not exist from collimator opening, but rather penetrates protective tube housing and some of the sides of the collimator

how is off-focus radiation produced?

when the electrons don’t hit the anode target (doesn’t strike the IR where it should)

what is the function of rating charts and cooling curves?

to protect the machine from overheating

define a heat unit.

tells us how much heat is produced during an exposure

what are the three prime factors that affect x-ray emission?

mAs, time, distance

what is the unit of measurement for x-ray quantity?

roentgen (R)

define an ampere.

amount of current flowing per second

what is the relationship between mAs and IR exposure?

directly proportional; mAs is used as a primary controller of IR exposure, as long as mAs is unchanged, IR exposure remains the same

what effect does increased kVp have on the speed and energy of the electrons in the x-ray tube?

directly proportional; if kVp is high, high energy electrons; kVp is low, low energy electrons

what is the relationship between kVp and IR exposure?

mAs is the controlling factor for density, or IR exposure; kVp when increased by 15% has the same effect as doubling the mAs

state the inverse square law.

intensity of radiation at a given distance is inversely proportional to the square of distance

what is the relationship between distance and IR exposure?

increased distance = decreased intensity = decreased receptor exposure

who discovered nearly every known property of x-rays?

Dr. Roentgen

when was the first radiograph produced?

December 22, 1895

early use of radiation could cause what?

radiation burns and operator electrocutions

what were unusual applications of early x-ray?

use of fluoroscope for fitting shoes

formula for velocity

v=d/t

(unit is m/s)

formula for acceleration

a=Vf-Vo/t

(unit is m/s^2)

formula for force

F=ma

(unit is N)

formula for momentum

p=mv

(unit is kg-m/s)

formula for work

w=Fd

(unit is J)

formula for power

p= w/t

(unit is W)

what are the 2 states of energy?

kinetic and potential

energy being expended

kinetic energy

british system = R

SI system =

C/kg

british system = rad

SI system =

gray (Gy)

british system = rem

SI system =

sievert (Sv)

SI system = C/kg

british system =

R

SI system = Gy

british system =

rad

SI system = Sv

british system =

rem

1 C/kg = ___ R

3876

1 R = ___ C/kg

2\.58x10^-4

1 Gy = ___ rad

100

1 rad = ___ Gy

0\.01

1 Sv = ____ rem

100

1 rem = ____ Sv

0\.01

measure of ionizations in air

exposure

what is exposure expressed as?

C/kg

what is air kerma?

kinetic energy released per unit mass

energy of radiation in air

air kerma

what is air kerma measured in?

Gray

what is the unit for absorbed dose?

gray (1 Gy=1J/kg)

an expression of the quantity of radiation energy absorbed by tissues being irradiated

absorbed dose

used to quantify occupational exposure or dose equivalent

Sievert

what unit specifically addresses the different biologic effects of different types of ionizing radiation to which a radiation worker may be exposed?

occupational exposure/dose equivalent

what is the standard unit for occupational exposure or dose equivalent?

rem

what unit is an expression of a quantity of radioactive material, not the effect of the radiation emitted from it?

Becquerel

what is the Becquerel quantifying?

the number of individual atoms decaying per second

amount of energy deposited by radiation in mass

absorbed dose

calculated for individual organs; based on absorbed dose but accounts for types of radiation

equivalent dose

calculated for whole body; add up equivalent doses to all organs and adjust for organ sensitivity

effective dose

absorbed dose is measured in..

mGy

equivalent dose is measured in…

mSv