Exam I Flashcards
(200 cards)
1
Q
What are X-rays?
A
Photons
discrete packets of energy
Electromagnetic Radiation
2
Q
Energy (E)=
A
1/ wavelength
3
Q
shorter wavelengths= _____ energy
A
Shorter wavelength= more energy
4
Q
Examples of high energy wavelengths
A
***x-rays
gamma rays
5
Q
Examples of Electric and Magnetic Fields
A
Radio/TV waves
microwaves
visible light
x-rays
6
Q
What determines energy and character?
A
Wavelength
7
Q
What are some properties of X-rays?
A
No charge, No mass
Invisible, Cannot feel
Travels in straight line
Travels at speed of light
Penetrates all matter
Ionizations
expose photographis emulsions
8
Q
You can measure x-rays with an electrometer.
T/F?
A
False. X-rays have no charge
9
Q
You can detect Lethal doses of x-rays (photons).
T/F?
A
False
can fill room and would never know
10
Q
What are the 3 fates of Ionizations in DNA?
A
Repair
Cell Death
Mutations
11
Q
How would you use photons for tumor cells?
A
Cell Death
12
Q
X-rays are carcinogenic.
T/F
A
True!
can cause tumor dvpt
13
Q
The General public radiation dose limit
A
1mSv/year
14
Q
Medical personell radiation dose limit
A
50 mSv/year
15
Q
Pregnant medical personell dose limit during gestation
A
<5 mSv/year
16
Q
ALARA is used to reduce one’s radiation dose. What does this acronym stand for?
A
As low as reasonably achievable
17
Q
_________ distance between personell and radiation source _________ exposure significantly
A
Increasing distance between personell and radiation sources decreases exposure significantyl
18
Q
The inverse square law states that the intensity of radiation (xrays/unit area) decreases with the distance from the source.
T/F?
A
True
19
Q
The inverse square law states that doubling the distance increases the x-ray intensity to 1/4th (1/2)2
T/F?
A
False. The inverse square law states that doubling the distance decreases the x-ray intensity to 1/4th
20
Q
According to the inverse square law, what does tripling the distance do?
A
Reduces x-ray intensity to 1/9th (1/3)2
21
Q
What is scatter?
A
scattered radiation from x-ray that bounced off the patient.
can hit person or ground and scatter around
22
Q
How can you protect personell against scattered radiation?
A
Use Shielding!
aprons, gloves, thryoid shield, glasses with lead
23
Q
What are the effects of scatter?
A
degrades image and increases personell exposure
24
Q
Collimation reduces scatter
T/F
A
True
beams down on small area that want to examine
25
What is a radiograph?
picture of pattern of x-rays emerging from the patient
26
Differential absorption is needed to create a radiographic image.
T/F?
True
27
How are x-rays produced?
when high speed electrons strike metal in an encased x-ray tube
28
How do you generate X-rays?
Electrons flow from Cathode (-) to Anode (+) through wire filament
29
A wire filament is made from ______ and has a _____ melting point.
A wire filament is made from**Tungsten** and has a **high** melting point.
30
What happens to the current passing through the filament?
It causes heating and electrons will "boil off"
31
How are the # of x-rays quantified?
as mAs
32
The # of X-rays are produced proportional to _________ (mA) and ________ is "on" (s).
The # of X-rays are produced proportional to **filament current** (mA) and **time current** is "on" (s).
33
The number of electrons at the cathode is proportional to mA.
T/F?
True
34
What does the product of (mA) x (s) determine?
the final # of electrons/ the # of x-rays produced
35
Will doubling mAs double the amount of x-rays produced?
Yes
36
What is the Filament Current (mA) limit for most vet machines?
300
37
The anode (+) is also known as the\_\_\_\_\_\_.
Target
38
How is the target quantified?
as kVp
39
Increasing kVp causing a greater voltage difference than increasing mAs.
T/F?
True
40
Why is the anode (+) only half the time? How can it be made (+) all the time?
normal alternating current (AC) makes the anode + only half the time.
Electronic trickery can make it + all the time by increasing x-ray yield= "high frequency"
41
When are x-rays produced at the anode?
when electrons interact/hit tungsten electron shell atoms
42
X-ray production at the anode is very efficient.
T/F?
False.
it is very ineffient. 99% of electron energy is converted to heat
43
What 2 x-rays are produced at the anode?
1. Characteristic radiation
\*\*\*2. Bremsstrahlungn (braking or stopping)
44
What are the two steps in the Bremsstrahlungn (braking or stopping) x-ray production?
1. The electrons hit the target and encounters tungsten atoms. Electrons from filament bend around nucleus and "brakes" b/c has large difference in electric charge.
2. As electrons slow (brake), it releases energy as an x-ray forms part of the useful x-ray beam
45
What are the 2 steps in characteristic radiation (collisional interaction) x-ray production?
1. Electrons from filaments deposit energy and eject electrons from inner shell. Electron from filament continues at lower energy.
2. Outer shell elecron fills inner shell void and energy deposited by electron from filament is released as a characteristic x-ray that is part of the useful x-ray beam.
46
How are most X-rays produced?
By the Bremsstrahlung (braking or stopping interaction)
47
What does energy in the x-ray beam depend on?
How close it is to the nucleus
48
mAs controls?
=mA + time
of x-rays produced
49
kVp controls?
energy of x rays produced
50
What is wrong with this radiograph?
Underexposed= too light
Either the kVp or the mAs is too low
51
What is wrong with this radiograph?
Overexposed or too dark
kVp or mAs is too high
52
How do you fix an underexposed (too light) radiograph?
Increase mAs (more x-rays and time)
or
Increase kVp (higher energy)
53
To correct underexposure, by how much can you increase mAs?
double
54
To correct underexposure, by how much should you increase kVp and why?
only ~15-20%
more energy can get through patient, it is equivalent to doubling mAs
55
Which radiographic image is high contrast? Which is low contrast?
Left- high contrast (black & white, few grays)
Right- low contrast (many grays, few black & white)
56
Which type of contrast image has a high mAs and low kVp?
What part of the body is this good for?
high contrast image
The abdomen!
57
Which imaging technique is good for the thorax?
Low contrast
low mAs, high kVp
58
Photoelectric effect is desirable in radiographic imaging. As it \_\_\_\_\_\_\_\_, kVp\_\_\_\_\_\_\_\_\_
As photoelectric effect **_decreases_**, kVp **_increases_**
59
Photoelectric effect is dependent on \_\_\_\_\_\_\_\_. This allows increased distinction between tissues. If you have differences in tissues then you will have differences in x-ray \_\_\_\_\_\_\_\_\_.
Photoelectric effect is dependent on **_atomic number_**. This allows increased distinction between tissues. If you have differences in tissues then you will have differences in x-ray **_absorption_**. For example, imaging of the abdomen relies on fat so must maximize the effect to distinguish betwen tissues.
60
Compton scattering is also desirable in radipgraphic imaging.
T/F?
False
61
Compton scattering is atomic number ________ meaning there is ____ distinction between tissues. As it \_\_\_\_\_\_\_\_, kvP \_\_\_\_\_\_\_\_.
Compton scattering is atomic number **_independent_** meaning there is **_less_** distinction between tissues. As it **_increases_**, kvP **_increases_**.
Absorption is similar between tissues so the contrast is reduced and now relying on the p for contrast!
62
Which body parts is compton scattering best used for?
Thorax
63
Low contrast= _____ scale
* X-rays are _____ penetrable
* More ____ Interactions
* Absorption is \_\_\_\_\_\_\_
Low contrast= **_long_** scale
x- rays are **_more_** penetrable
more **_Compton_** interactions
Absoprtion is **_more uniform_**
64
High contrast= ______ scale
* X-rays are _____ penetrable
* More ____ Interactions
* Absorption \_\_\_\_\_\_\_
High contrast= **_short_** scale
X-rays are **_less_** penetrable
More **_Photoelectric_** Interactions
Absorption **_either occurs or not_**
65
What provides contrast in the Thorax? Will you need to maximize this contrast further?
Air
No. already have subject contrast due to air in lungs
66
What provides contrast in the abdomen? Will you need to maximize this contrast further?
Fat.
Yes. use low kVp and high mAs photoelectric effects
67
This radiograph is\_\_\_\_\_\_\_\_.
What should you do to correct it?
Overexposed
Either decrease mAs by 1/2 or decrease kVp by 15%.
68
This rad was made using 5mAs and 100kVp. What technique should you use to try to correct this?
Can increase kVp by ~15% from 100 to 120kVp.
69
What 2 things are needed to make an image with radiograpy?
Absorption and transmission
70
What problems does scatter cause?
Degradation of image
and
Increases personell dose
71
When do we need to use a grid while taking radiographs?
When the patient is thicker than 10cm b/c they create more scatter.
Grids intercept scatter from the patient before it reaches the film
72
Grids are composed of alternating strips of ______ and \_\_\_\_\_.
lead and aluminum
must be lined up properly
73
When using a grid you need to use 2-3x more photons or a higher mAs due to absorption of the primary beam by lead.
T/F
True
74
Where do you position the grid?
Between the patient and cassette.
75
What 2 main methods do you use to record an image (converting x-ray pattern exiting patient into a visible image)?
1. Analog conversion (film/screen systems)
2. Digital Conversion
76
\>90% blackness is due to light vs x-rays.
T/F?
True
X-ray film is much more sensitive to light
77
What is a digital radiograph?
Converting a recorded map of x ray transmission through a patient to a digital file into a digital image
78
What is a digital image?
Map of x-ray transmission converted to digital matrix
79
Digital radiograph is composed of pixels, each with an assigned shade of gray. In order to see a lesion on the image, the pixels must be _______ than the lesion.
Digital radiograph is composed of pixels, each with an assigned shade of gray. In order to see a lesion on the image, the pixels must be **smaller** than the lesion.
80
Pixels must be _______ and there must be a large number of ______ shades to obtain good contrast resolution.
Pixels must be **small** and there must be a large number of **gray** shades to obtain good contrast resolution
81
In what format are Digital Imaging files?
DICOM
digital imagin communications in medicine
82
What's in a DICOM file?
Image
Header (practice, patient, device info)
83
Why is it important to have digital images in DICOM format?
This is the viewing software to view your images
It provides portability
84
What are the 2 types of digital radiography?
CR= computed radiography
DDR (DX)= Direct Digital radiography
85
An image plate in a cassette like- housing similar to film-screen is characteristic of....?
Computed radiography
86
Use of a flat panel detector with No cassette to process and No plate reader with readily available images is characteristic of ....?
Direct Digital Radiography
87
In order to view the radigraphic image from Computed Radiography (CR), cassettes must be processed in a place reader for 90seconds.
T/F?
True!
88
Besides flat panel, what other type of Direct Digital Radiography is there?
CCD (charge coupled device)
89
How does the CCD radiography system work?
the CCD chip converts light to electrical charge
The image quality is a function of light collection, lens and pixels in a camera chip
90
What is the most crucial component of the CCD system?
light collecion and the lens
91
What are the 2 kinds of flat panel direct digital radiograpy systems?
Indirect & Direct Digital Detectors
92
The difference between indirect & direct flat panel digital radiograph detectors:
Indirect detector has a light intermediary with and intensifying screen
Direct has do NOT have a light intermediary and uses a photoconductor
93
Is there a detectable difference in quality between the indirect and direct digital flat panel systems?
No.
Though direct is theoretically better
94
How many pixels do the flat panel digital images have in each dimesion
\>2000 pixels
95
What are some benefits of flat panel Digital Radiography (DX)?
no cassettes, no camera, no lens
immediate exposure, image ready and viewable QC
excellent quality image, portable image plate
96
With high contrast images bones are _______ and gas is \_\_\_\_\_\_\_
With high contrast images bones are **white** and gas is **dark**
97
With low contrast images, bones are\_\_\_\_\_\_\_ and gas is \_\_\_\_\_\_
With low contrast images, bones are **gray** gas is **gray**
98
Inherent detail of ______ is slightly better than \_\_\_\_\_\_.
Inherent detail of **film** is slightly better than **digital**
BUT digital has better contrast
99
In film the exposure latitude is narrow. What is exposure latitude?
The extent to which a film, image plate of flat panel can be over or underexposed to radiation and still get a good image
100
Digital Exposure Latitude also has a narrow margin of error.
T/F?
False!
With digital, you do not hve to be that precise with mAs and kVp.
101
Which images were taken with Analog, which with digital?
A B C taken with analog, D E F taken with digital all with different exposures
102
Since Detail is slightly better with film images, what happens if a digital image is underexposed or has low exposure?
The image looks grainy and has more "noise"= loose detail
103
There is also a limit to plate overexposure in digital imaging. What happens if the digital image is overexposed?
the plate becomes 'saturated' and the anatome 'disappears'.
The computer cannot compensate anymore so everywhere that is overexposed appears black
104
Define Contrast Optimization:
the range of light intensities a medium can capture
105
Explain Contrast optimization with application of additionaly processing that 'normalizes' the image
Dark regions are made lighter and lighter regions made darker
= smooth 'wide latitude' radiograph
106
What is post processing and when should it be done?
the ability to change image contrast and blackness after acquisition
done with digital
107
What are some common misconceptions about Digital Radiography?
Lower exposure factors than film
Artifacts and other technical problems are less
108
What is the PACS system?
**P**icture **A**rchive and **C**ommunication **S**ystem
host of technologies that contribute to image creation/disribution/viewing/archiving
109
110
What are components of the basic PACS?
Device, Network, Image Archive 'server', Work stations, Communication protocol (DICOM), redundancy/disaster recovery
111
Which has the best detail? Contrast resolution?
Radiograph, CT, or MRI
Radiography has the best detail
MRI has the best contrast resolution!
112
Define Spatial Resolution
the ability of an imaging system to differentiate between two adjacent objects
113
The small differences in spatial resolution between radiography, CT, and MRI is offset by the huge differences in contrast resolution.
T/F?
True
114
Can contrast resolution be manipulated in CT and MRIs like it can in digital rads (DR)?
Yes with post processing
115
The term that describes sophisticated radiographic sliced images from a patient created from digital information
Computed Tomography
116
How does computed tomography work with the x-ray tube?
The x-ray tubes circles around the patient and the attenuation of the beam is measured as it rotates around the patient and the computer creates sliced images of that
117
Which component of the computed tomography deals with quantification of x-ray attenuation?
Computed
118
Which component of computed tomography solves the problems related to compression of 3D to 2D?
Tomography
119
Describe how the image is produced based on x-ray attenuation?
x-ray beam tube rotates around patient
transmitted beam intensity measured by detectors
computer reconstructs image
120
Which image describes helical mode?
B
A is single slice mode
121
How would you describe helical mode?
with a continuous table and x-ray tube movement that allows faster scanning
122
Describe a multislice (multidetector) CT
can get more than one slice per tube revolution
can image entire thorax in \<5s into thin slices and still retain tremendous detail
123
Can you reformat original images into other viewing planes with tomographic CT?
Yes
124
What does 2D reformatting allow you to do?
Build images in other planes from transverse data
125
Definition of medical contrast medium
substance used to enhance the contrast of structures or fluids withing the body in medical imaging
126
For which structures of the body are medical contrast mediums commonly used to enhance?
blood vessels, vascular leaks, GI tract
127
Describe IV Contrast mediums used for CT
are iodinated, given IV, attenuates x-rays, creates hyperattenuation in vessels or if there are leaks in tissue
128
Can you use IV contrast medium for CT to visualize vascular permeability or increased vascularity?
Yes
129
How could you use IV contrast medium for CT to evaluate brain tumors?
Brain tumors alter the BBB. If you give IV iodinated substance the substance will show up as a different opacity in the image because with a tumor it will leak out
130
Name some uses for CT
Nasal Disease, Thoracic masses; resectable, fragmented medial coronoid process, radiation therapy planning, portal vein anomalies
131
The contrast resolution is greater in CT than MRI.
T/F?
False
Contrast resolution is much greater with MRI
132
In a MRI the image appearance is dependent upon\_\_\_\_\_\_\_\_
chemical composition
133
Two 2 chemical compositions are used to create MRI images?
Water ( free and tissue)
Fat
134
With a MRI, are you able to reformat planes?
No.
You can image in any plane but no reformatting. you must image in the plane you desire
135
How does the MRI work?
Very Strong Magnetism!
136
How does the MRI magnet compare to refrierator magnetism of 50 Gauss?
It has 300x more magnetic field .
The earth's magnetic field is only 0.5 gauss
137
The only hazard with the MRI is ionizing radiation.
T/F?
False!
There is no radiation hazard with MRI. Only the dangers of flying objects from the strong magnetism
138
With MRI image types, what creates a high signal?
Water
139
What color will Increased signal, due to water for example, make the MR image appear?
white
140
Most lesions are what type of composition? Water or Fat?
Water
So want to look for signs of water/ increased signal when looking for lesions
141
Low signal strength on an MR appears.....?
black
142
Water's Hydrogen protons behave like ______ in the MRI. The main magnet causes these protons to ______ while radio wave (RF) causes protons to \_\_\_\_\_\_\_.
Water's Hydrogen protons behave like **little magnets** in the MRI. The main magnet causes these protons to **align with field** while radio wave (RF) causes protons to **knock out of alignment in X-Y plane**
143
\_\_\_\_\_\_\_\_\_\_ protons rotate and create signal in receiving coil
misaligned
144
Name the 5 common proton sequences of the MRI
proton density, T1, T2, FLAIR, STIR
145
In T1 proton sequence the magnet primarily "hears"......
protons in fat
146
In proton density sequence the magnet primarily "hears".....
all protons!
147
In T2 proton sequence the magnet primarily "hears".....
protons in free water, tissue water, and fat
(fat and water have high signal)
148
In FLAIR proton sequence the magnet primarily "hears"......
protons in tissue water
149
In STIR proton sequence the magnet primarily "hears".....
nulls signal from fat (gets rid of the signal from fat) so hears free water and tissue water
150
What color are bones in CT, rads, and MRI?
white bones- CT and rads
black bones- MRI
151
Why are bones black in the MRI?
not enough protons in bone to get a signal so appears black in a MRI
152
What proton sequence does this MRI image depict?
PD (proton density)
the magnet "hears" all protons from bone, fat, CSF
153
Which proton sequence does this MRI image depict?
T2
2 signals (water and fat)
free water & tissue water, fat
154
Which proton sequence does this MRI image depict?
T1
1 signal
protons in fat, high signal
155
Which proton sequence does this MRI image depict?
FLAIR
nulls signal from fat
156
Most lesions, such as this infarct, result in increased \_\_\_\_\_\_\_. Which proton sequence was used in this MRI image?
tissue water
T2
157
FLAIR stands for _________________ and nulls signal from \_\_\_\_\_\_\_\_.
FLAIR stands for **fluid attenuated inversion recovery** and nulls signal from **free fluid**
helps see lesions better in the tissue b/c does NOT null tissue fluid
158
STIR stands for _____________ and nulls signal from \_\_\_\_\_\_\_\_\_\_
STIR stands for **Short Tau Inversion Recovery** and nulls signal from **fat**
right image rids fat from medullary cavity and makes lesion more obvious
159
What is Gadolinium and with which proton sequence can you use it with?
IV Contrast medium for MRI. Paramagnetic compound that speeds up proton relaxation. Used to detect defective BBB or inflammation
Only used with T1
160
For what do we mostly use neuroimaging in vet medicine?
Brain and Spine
161
What kind of image is this?
CT
bones are white
162
What type of MR image is this?
T2 weighted
fat and water signals
163
What are the 5 opacities in radiographic imaging?
Air\> Fat\> Water\> Bone\> Metal
Black\> Dark Gray\> Gray\> Light Gray\> White
Increasing opacity & rad density, decreasing radiolucency
164
Why are opacities important?
different structures can be identified and differentiated
165
What are the issues of 2-D rads?
magnification/distortion, loss of depth perception, superimposition & summation shadows
166
What happens when you magnify the radiographic image?
image is large but less sharp
167
Where if there is unequal magnification like in the case if you cannot fully extend one hip for a rad b/c it is painful or fibrotic causing it not to extend?
The image becomes distorted
168
How would you define superimposition?
a structure that appears in an unexpected location and misinterpreted as a lesion.
Ex: looks like a lytic lesion on ischium, but just overlying anal sac
169
Does this right lateral view depict a lung nodule or due to metastases or is this a product of superimposition?
The VD view shows NO "lung nodule" it was superimposition from a tick
170
How would you define summation sign?
it's a special case of superimposition where overlapping structures create a summation opacity that is not really present in the patient
171
What type of summation does this rad of swiss cheese depict?
Negative summation
the overlapping areas are more radiolucent
172
Define the silhouette sign
the effacement of the border of two structures of the same radiographic opacity that are in contact
173
Which vessel is an example of the silhouette sign in the thoracic cavity? Which vessels can be seen?
Coronoary artery cannot be seen on myocardium
Pulmonary arteries CAN be seen on the lungs
174
What vessel is depicted by the arrows in the image?
Pulmnary artery
Cannot say coronary artery b/c remember it has the same opacity as the mediastinum. If the coronary artery were mineralized you could say that.
175
In which positional view will fluid surround the heart if there is a pleural effusion?
In which positional view will the lungs surround the heart if there is a pleural effusion?
DV: fluid surrounds heart
VD: lungs surround heart
176
In which positional view can you see the heart with a pleural effusion? When it is surrounded by fluid or the lungs?
Can see heart when surrounded by lungs in VD view when there is a pleural effusion.
Cannot see when surrounded by fluid b/c of the silhouette
177
What is the ONLY way to name radiographs?
First Word= point of entry
2nd word= point of exit
178
You can look at a radiograph and tell which it was taken.
T/F?
FALSE!
You think you can but you can't!
179
What is the ONLY way to orient images?
Anima's head always to left
cranial or proximal to top
No convention for extremities regarding lateral or medial
180
What are Roetgen Signs?
6 standard terms used to describe changes in structure in a radiograph
181
What are the 5 Roetgnen signs?
Size, Shape, Number, Location, Margination, Opacity
182
Is this the correct orientation of the radiograph?
No.
Cranial should be oriented to the left (patellar left)
183
This cat has fluid in peritoneal space that resulted in reduced visualization of abnormal organ. This is an example of.......?
Silhouette Sign
184
Abdominal Radiography depends on ______ for contrast
Abdominal Radiography depends on **fat** for contrast
185
What technique with kVp and mAs should you use with film?
low kVp and high mAs
186
Inclusion of which boundaries comprise a complete examination?
Cranial edge of diaphragm
Caudal greater trochanter of femurs
Lateral dorsal and ventral soft tissue boundaries
187
For survery rads do you need to fast or use enemas with the patient?
No
188
In which view will the fundus be down and filled with fluid and the pyloric antrum on top and filled with gas?
RL or LL?
Right Lateral
189
In which view will the fundus and the body of the stomach fill with fluid and the pyloric antrum fill with gas?
VD or DV?
VD when patient is in dorsal recumbency
190
In which view is gas located in the pyloric antrum and fluid in the fundus?
VD or DV?
VD
191
What technique do you use to see the urethral and perienal region?
pull pelvic limbs cranially
192
Why is it good to look at the urethra in male dogs?
Good to look for calculi in the urethra. The os penis narrows further down and calculi like to lodge through here in the urethra
193
What are the differences in peritoneal fat, pancreas, spleen, stomach wall fat, position of pylorus, and cecum size in dogs vs. cats
Cats
more perioneal fat so you will have better radiographic detail; pancreas extended to left; smaller spleen; more fat in stomach wall; more medial pylorus; can't really see cecum
194
What shape does the cat spleen look liek radiographically?
Small triangle
195
Can you use medial displacement of the pylorus as a sign of hepatomegaly in the cat?
No because in the cat the pylorus is closer to the center
But you can in the dog
196
What does the cecal junctions does the dog have that the cat does not?
cecocolic sphincter or junction
Cat Does have a ileocolic junction
197
In a VD view the cecum is located on the ______ of the abdomen
n a VD view the cecum is located on the **right** of the abdomen
198
What are some common adominal rad summation shadows that can fake you out?
Prepuce
Gas in anal sacs
199
Prepuce, skin folds, and gas distended in anal sacs can fake you out?
True
200
