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Thomas Edison
discovered fluoroscope. real time. the difference between x-ray and fluoroscope is the dynamic
x-ray tube has two side they are
positive and negative.
negative
cathode-filament
positive
anode-target
the difference between positive and negative is
the kilo-voltage (kVP)= high potential difference
the % of x-ray
1% x-ray
99% heat
common inches and cm of x-ray cassettes
8 x 10 inches multiply by 2.5 = 20x25cm
10 x 12 inches multiply by 2.5=25x30cm
14 x 17 inches multiply by 2.5=35x43
for x-rays to be produced you need 4 things
vacuum=pyrix glass
source of electron=filament
target for electron=anode: the focal spot
high potential difference between the source and the target=negative and positive=kVp
photon
the smallest possible unit of electromagnetic energy. x-ray is a photon
voltage between source and target
the negative will go to the positive. the energy is converted into 99%heat and 1% x-ray
negative and positive is
the potential difference. thermoeotic emission = heat related and form a space charge
the target is the
anode
wavelength
distance from one crest to the next
frequency is the
number of times per second that a crest passes a given point
a increase in frequency will
decrease wavelength and equal more energy
kVp controls
wavelength and frequency
radiation=x-rays they
travel in a straight line
cannot be refracted by a lens
diverges into space from its source
cannot be detected
3 types of x-ray
primary-
what leaves the x-ray tube to the patient
scatter (secondary)
Once
primary beam hits solid matter, what is not absorbed will scatter in many
directions
remnant
-what passes through the body what's left over Remainder of the primary been after its been attenuated Pattern
of intensity is what creates the radiographic image
The beam that passes through the patient and exposes the film is called “Exit
Radiation
”This“Exit” radiation is what creates the image.
White image
on
film is what was absorbed
Black
is what was exposed
Shades of gray
are what was attenuated
LATENT IMAGE
THE INVISIBLE IMAGE ON AN EXPOSED FILM OR PSP PRIOR TO PROCESSING
MANIFEST IMAGE
A VISIBLE IMAGE AFTER PROCESSING
Radiographic Factors
Time (s)
Milliamperes (mA)
Millamperes per second (mAs)
Kilovoltage Peak (kVp)
Distance
time
Duration of the exposure of
radiation
measured in seconds
Effect on Film
Longer
exposure Time will increase
Density of Film & Patient Exposure
Shorter
exposure Time will decrease Density of Film & Patient Exposure
Milliamperage (mA)
the quantity current going to the filament
Milliamperers per second (mAs)
the total amount of radiation expoure
kilovoltage peak (kVp)
controls the energy of the radiation beam. also known as high potential difference. more energy more kVp
distance
is the SID how far away from the source x-ray tube
SID inverse square law
the closer more exposure
farther away less exposure
SID
Source to Image Receptor Distance the x-ray tube to the cassette itself
SOD
Source to Object Distance
OID
Object to Image Receptor Distance
Focal Spot
controls detail
the smaller the focal spot the better the detail
the larger the focal spot the less detail
Four Principles in Image Quality
Density
Contrast
Detail
Distortion
Density
The amount of blackness of an image
Also known as
optical density
Controlled by mAs
Increase mAs = increase blackness
Decrease mAs = decrease blackness
Contrast controlled by kVp
The degree of difference between
the light and dark areas of an x-ray
High contrast
= more black and white
Low contrast
= overall gray appearance
Detail
The degree of sharpness of a structural line on an x-ray Focal spot size
Distortion
Refers to a variation in the size and/or
shape of the image in comparison to the object it represents
misreprensentation of size and shape
size- in x-ray magnification looks bigger than it is
shape - shorting or elongation
Radiation Units/Measurements
Roentgen (R)
Radiation absorbed dose (RAD)
Roentgen equivalent in man (REM)
Roentgen (R)
Amount of radiation in air (not pt. dose)
Radiation absorbed dose (RAD)
radiation dose what goes into the patient
Roentgen equivalent in man (REM)
the biological effect the damage to the body
not all x-rays are equal
x-rays 1 R=1RAD=1REM
at least 6 feet from the beam
3 CARDINAL RULES FOR RADIATION
SAFETY
time
distance
shielding
Inverse Square Law
In regards to radiography
The intensity of the radiation is INVERSELY proportional to the SQUARE of the
Distance
ALARA
As low as reasonably achievable
For X-ray Techs, the maximum radiation dose per year is 5 rem or 50mSv
Applies to workers age 18 and over and
not pregnant.
Device for monitoring radiation exposure.
OSL-optically stimulated luminescence (read by laser)
Imaging Systems
Analog
Film Screen
Digital
CR
DR
Fluoroscopy
Dynamic or real time imaging
(X-ray are static/still images)
Alarm sounds after 5 minutes of total exposure
Author
139shay
ID
281819
Card Set
notebook exam 1
Description
notebook exam 1
Updated
2014-09-01T19:33:25Z
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