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1
Q

projection

A

It is where the CR enters and exists the patient towards the IR

ex: AP is anterior posterior the CR enters the pt anteriorly and exists posteriorly before it interacts with the IR

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2
Q

Position

A

How the pt body is placed or the placement of the body part in relation to the IR

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3
Q

Axial

A

angulation of the x-ray tube

ex: cephalic (head) or caudal (feet)

if you see the feet angle to the feet

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4
Q

Pt is laying on their back

A

supine

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5
Q

what is the term for laying down?

A

recumbent

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6
Q

Pt is laying on their stomach

A

prone

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7
Q

What is the Sims position?

A

Pt is in left lateral, right leg is moved in front of patient

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8
Q

Trendelenburg

A

Head is lower then the head

“Toes are higher”

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9
Q

Fowlers

A

Feet are lower than the head

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10
Q

In a decubitus position the patient is supine what is this referred to?

A

dorsal

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11
Q

In a decubitus position the patient is prone what is this referred to?

A

ventral

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12
Q

Pt is in a left lateral decubitus what marker do you put?

A

Right- always mark the side up

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13
Q

Pt is in a left dorsal decubitus what marker do you put?

A

Left-mark the side closest to the IR

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14
Q

Plane that divides the body into left and right halves (equal)

A

Mid sagittal

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15
Q

coronal plane

A

divides the body into anterior and posterior parts

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16
Q

What does the prefix “mid” refer to when speaking about body planes

A

means split into equal halves

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17
Q

plane that divides the body into superior and inferior parts

A

transverse or horizontal

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18
Q

movement away from the center of the body

A

abduction

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19
Q

movement toward the midline

A

adduction

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20
Q

Pt is asked to rotate their arm towards the midline of the body what kind of movement is this?

A

medial rotation

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21
Q

RT positions pt’s arm so that it is moving away from midline

A

abduction

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22
Q

In a PA chest why do you have the PT roll their shoulders forward

A

puts the scapulas in a more lateral position which allows better visualization of the lungs

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23
Q

how many ribs must be seen on a PA chest

A

10 posterior ribs

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24
Q

why is the lateral chest performed on the left

A

heart dips down to the left and it reduces magnification

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25
where is the CR entrance point for a lateral chest
midcoronal plane at the level of T7
26
what is the purpose of the lordotic view
shows apices of the lungs
27
is there a tube angle for lordotic?
No PT takes a few steps forward while having their back against the board 72 inches
28
what makes a good lordotic image
clavicles are projected above the apices clavicles appear to be straight
29
CR of a lordotic chest
3-4 inches below the jugular notch PT is leaning backward 15-20 degrees
30
how many posterior ribs are needed to be seen on an AP portable chest
8-9 posterior ribs
31
for a sthenic pt the top of the IR for a portable AP chest should be placed
1.5 inches (4cm) superior to the soft tissue of the shoulder
32
how do you know if there is rotation in an AP portable chest
asymmetrical ribs and clavicles
33
what is the SID for lateral view of a soft tissue neck?
72 SID ensure that the top of the light field is above the EAM
34
what is a diagnostic lateral soft tissue neck?
air filled trachea from the pharynx to the midthoracic region
35
what is the CR for AP soft tissue neck?
1 inch superior to jugular notch
36
what is the carina associated with?
bifurcation of the trachea
37
how should the Vascular markings of the lungs appear on a PA chest
should appear thin in the superior portion of the lungs
38
what health condition demonstrates absence of the diaphragm contour and blunting of the CP angles
pleural effusion
39
which abnormalities are found in a pt with CHF?
enlarged cardiac size pulmonary edema
40
types of radiation measurements
radiation in the primary beam leakage radiation amount of radiation absorbed by the pt amount of radiation absorbed by the healthcare provider
41
what is leakage radiation measure?
the amount of secondary radiation escaping the x-ray tube
42
what are the common radiation measurements?
exposure air KERMA absorbed dose equivalent dose effective dose
43
what are the two categories of radiation measurement?
air and tissue
44
what does the radiation in air measure?
measures the radiation intensity
45
what are the units used to measure radiation intensity (air)
exposure air KERMA
46
what does the radiation in tissue measure?
measures dose
47
what are the measurements used to determine the effects of radiation on tissue?
absorbed equivalent effective
48
how is the intensity of the X-ray beam measured?
exposure air KERMA tells us how radiation is coming out of the x-ray tube
49
how is the leakage radiation from the tube measured?
exposure air KERMA
50
how is the INITIAL dose the healthcare provider and pt receive called?
absorbed dose
51
what does absorbed dose tell us?
absorbed energy short term effects-skin erythema or hair loss does NOT do a good job of detecting long-term effects such as cancer
52
effective dose
solely used to detect long-term effects such as cancer not used to calculate short-term effects and absorbed energy
53
if mA is increased what happens to intensity, exposure KERMA, and absorbed equivalent, effective doses?
it increases everything because each calculation is influenced by the same variables
54
radiation in the air is measured by
exposure Air KERMA
55
absorbed dose measures
radiation in tissue
56
equivalent dose measures
effects of radiation on tissue
57
what does ESE stand for
entrance skin exposure
58
ESE measures
the intensity or quantity of radiation in air at the level of the patient's skin
59
DAP is used to measure
the total amount of radiation delivered to the patient from diagnostic imaging equipment
60
if kvp is increased what happens to intensity, exposure KERMA, and absorbed equivalent, effective doses?
it increases everything because each calculation is influenced by the same variables
61
if distance is increased what happens to intensity, exposure KERMA, and absorbed equivalent, effective doses?
results in the decrease of all the values due to the inverse square law
62
how does a decrease in kvp affect the absorbed dose to the pt?
decrease in kvp affects the absorbed dose it also decreases the average energy of the x-ray beam and the total number of photons created fewer photons means less dose is absorbed by the pt
63
what are the three types of methods used to quantify radiation in tissue
effective dose absorbed dose equivalent dose
64
radiation that escapes the protective housing of the tube is known as what?
leakage
65
what is another form of secondary radiation?
scatter
66
how is scatter produced?
Compton scattering
67
what is attenuation
is a loss of intensity of the X-ray beam as it passes through matter
68
what is considered primary radiation radiation that: 1. produced within the pt 2.scatter from interactions within the pt 3. that escapes the protective housing 4. exits the window in the tube housing
radiation that exits the window in the tube housing
69
what does an X-ray beam interact with as it interacts with matter?
interact with air molecules and knock out an electron out of its orbit ionization
70
what does exposure measure?
the number of ionizations in air
71
how is the X-ray beam's intensity measured?
through exposure
72
increase in the x-ray beam leads to the increase of what?
ionizations and exposures
72
the number of ionizations is directly proportional to what?
number of photons in the x-ray beam this is the reason why if ionization is increased then exposure (the number of ionization in the air) will increase too
73
what are the units of exposure?
coulombs/kilogram
74
what does Coulombs measure?
measures charged particles
75
1 coulomb is equal to what?
6.242x10^18 ionizations
76
if mA is increased what happens to photons, ionization, exposure
all increased because the same variables influence all the calculations
77
if distance is increased what happens to photons, ionization, exposure
all decrease because the same variables influence all the calculations and due to the inverse square law
78
what does air KERMA measure
measures the energy of ionizations in the air
79
what does KERMA stand for
kinetic energy released per unit mAss
80
if the intensity of the beam is increased what happens to ionization energy and air kerma
it increases
81
what are the units for kerma?
gray
82
what does 1 gray equate to
1 joule/kilogram
83
you can use exposure and air kerma to measure
test radiation coming from the tube measure leakage radiation measure scatter radiation
84
how is exposure different from air kerma?
measures only the # of ions in the air units are coulombs/kilogram
85
how is air kerma different from exposure?
measures the energy of ions units are gray
86
when measuring the intensity of the primary beam what dosimeter position will demonstrate the highest air kerma
the measurement that is closest to the tube
87
primary bi-product of x-ray interactions in air is
free electrons
88
the process that x-rays created charged particles such as free electrons
ionization
89
which of the following best describes radiation exposure quantity of radiation: 1. directed at the pt 2. absorbed in the pt 3. Passing through the pt 4. energy absorbed in the air
quantity of radiation directed at the patient
90
some of the radiation is absorbed by the tissues of the body where does some of this energy go?
it is absorbed in the photoelectric effect and Compton scattering
91
what is the total amount of energy absorbed in the body as a result of Compton scattering and photoelectric effect is known as?
absorbed dose
92
what is the definition of absorbed dose?
energy absorbed in the body per unit mass remember to think of its units joule=energy kilogram=mass
93
The SI unit of measurement for absorbed dose
gray
94
radiation effects on tissue
equivalent dose effective dose
95
absorbed dose formula
joules/kilograms
96
what effects does the equivalent dose take into account?
the effects of different radiation types have on anatomy
97
the type of radiation with the highest equivalent dose
alpha radiation = 2EqD
98
what is the effective dose used for?
used to assess the degree of radiation including biological damage per different tissue types
99
what tissue has the lowest tissue weighting factor?
brain (0.01)
100
what is the weighting factor for X-ray?
1
101
why is the absorbed dose used?
it is used to predict short-term or early radiation injuries
102
examples of short-term radiation injuries
sperm depression skin erythema epilation
103
what kind of tissues absorb more radiation
tissues that have a high atomic number high density
104
when looking at a radiograph what do the dark areas represent?
low absorbtion of the x-ray means it has low z# and low density
105
what are examples of tissues that absorb a minimal amount of radiation?
tissues that have air fat
106
what is an example of a tissue that absorbs a moderate amount of radiation (appears gray on a radiograph)
muscle
107
what is the absorbed dose affected by?
mA kVp distance density and z#
108
what is the definition of linear energy transfer?
the rate at which radiation energy is deposited in matter
109
what causes more biological harm?
higher LET
110
true or false X-rays have a high LET
false
111
true or false alpha particles have a high LET
true
112
what is the formula for an equivalent dose?
EqD=D(absorbed dose) xWr (radiation weighting factor)
113
what happens to relative biological effectiveness, radiation weighting factor, and equivalent dose if LET is increased?
everything is increased
114
what is the purpose of the equivalent dose?
used to compare the biological damage from different radiation types
115
factors that affect equivalent dose?
radiation type absorbed dose mAs kVp exposure time distance
116
units for equivalent doses?
sierverts
117
the formula for effective dose
EfD= D (absorbed dose) x Wr (radiation weighting factor) x Wt (tissue weighting factor)
118
the most sensitive tissue to radiation is
bone marrow
119
the least sensitive tissue to radiation is
brain
120
why are the values of effective dose and equivalent dose different despite having the same value of absorbed dose?
tissues have different sensitivities to radiation therefore they have different tissue weighting factor
121
what is another term for effective dose?
whole body dose
122
why would we use an effective dose?
to compare the risk of cancer based on different radiation types and tissue types identify long-term effects of radiation exposure
123
factors that affect effective dose?
absorbed dose radiation type (Wr) tissue type (Wt) mAs kVp distance
124
what do you do if a question asks you to calculate the effective dose when there are two different types of tissues?
you add the values up and then multiply by the absorbed dose and radiation weighting factor
125
what factors are needed to calculate an effective dose?
absorbed dose exposed tissue types radiation type
126
true or false the skin is sensitive to radiation
false
127
the risk of radiation-induced stochastic effects is reduced by adherence to which of the following dose limits?
effective dose limits to the whole body
128
why are vital signs important in medical imaging?
helps evaluate the critical functions of the body
129
what is the normal temperature for an adult?
98.6 (oral)
130
how many degrees difference is the tympanic temperature?
+1
131
how many degrees of difference is the axillary temperature?
-1
132
how many degrees difference is the rectal temperature?
+1
133
what is the pulse rate?
the number of pulses per minute
134
what is pulse amplitude?
signifies the strength of the pulse
135
what is the average pulse rate?
60-100bpm
136
what is the definition of blood pressure?
The lateral force exerted on the arterial walls.
137
what is the average blood pressure of a healthy adult?
systolic (contraction)=100 to 120 diastolic(relaxing)= 60-80
138
what is the definition of respiratory rate?
is the number of breath cycles (inspiration and expiration) per minute
139
what is the average respiratory rate?
12-20 breaths per minute
140
what tool is used to measure oxygen saturation in the blood?
pulse oximeter
141
what is the normal percentage of oxygen saturation?
90-100%
141
which blood pressure reading is associated with the left ventricle?
systolic
141
what should a technologist do if you identify an abnormal viral sign in a pt?
stop the procedure help stabilize the pt call for help
141
the diastolic bp is a measurement of the pressure exerted on the arterial walls during
relaxation of the left ventricle
142
In a trauma situation which two arteries are best for assessing a pt pulse due to their larger size?
carotid femoral
143
what is an EKG?
it is an electrical image of the heart
144
what is the P-wave in an EKG?
represents the electrical activity through the atria
145
what is the QRS complex?
movements of electrical pulses through the ventricles aka ventricular systole
146
what is the ST segment?
shows the ventricles contracting but no electrical activity is flowing through it
147
what is the T-wave?
shows when the ventricles are resetting electrically and preparing for their next muscle contraction aka ventricular diastole
148
when is ekg used in medical imaging?
EKG gating it allows images of the heart without motion blur and images are collected in between beats
149
the first phase of contraction of the heart involves the contraction of the
right and left atria
150
from the ventricles, blood is pushed
into the pulmonary artery and aorta
151
how many leads are connected to the pt during an EKG
3
152
what are the two types of lab testing that are used in diagnostic imaging?
kidney function blood clotting
153
what is BUN?
blood, urea, nitrogen normal: 7-21
154
What kind of health condition is associated with a BUN above 21
means the kidneys are struggling to function properly
155
What kind of health condition is associated with a BUN above 50
suspected renal failure do not give intravenous contrast
156
what is creatinine?
chemical byproduct of metabolism (muscles) normal: 0.7-1.5
157
creatine value of 1.5 indicates
pt kidney cant filter iodinated contrast
158
what factors affect the value of creatinine?
age gender muscle mass hydration status
159
why is identifying creatinine levels important in diagnostic imaging?
can be a contraindication for injecting IV contrast ONLY when the level is HIGH
160
what is GFR
glomerular filtration rate estimates the filtration of the kidneys normal: 90-120
161
what does a GFR level below 90 indicate?
pt kidney is not properly functioning to filter out the contrast
162
what factors affect GFR?
age gender muscle mass hydration status
163
what is a pt test?
prothrombin time measures the liquid portion of blood to clot normal: 11-13.5s
164
what contraindication is associated with a patient whose pt is above 13.5s
patient's blood is not clotting properly
165
what is a ptt test?
partial thromboplastin time normal: 25-35s
166
what is an INR test?
international normalized ratio identifies blood coagulation normal: 0.8-1.2s
167
what is the platelets test?
identifies blood coagulation normal: 150k-400k
168
what does a high platelet count indicate?
clotting disorders
169
what does a low platelet count indicate?
bleeding disorders
170
what are the contraindications for interventional or invasive procedures?
PT PTT INR platelets
171
what are the contraindications for intravenous contrast?
BUN Creatinine GFR
172
what information would a GFR test provide?
rate at which the kidneys filter waste from the blood
173
true or false water-soluble iodine is the only contrast that is considered safe for IV injection
true
174
what is an ionic contrast?
when placed in a solution it breaks up into ions (charged) NOT desirable
175
why is ionic contrast not desirable?
due to charged particles, it is highly toxic high osmolarity
176
what does the term osmolarity refer to?
concentration of particles in a solution
177
what factors should be taken into account before a pt is given contrast?
diet renal function allergy premedication
178
what are the diet factors pts need to take into account before contrast injection?
pre-hydrated for 1 day NPO for 1 hour post hydration 1 day- reduces the toxicity of contrast
179
what lab tests need to be done before IV contrast injection?
BUN creatinine GFR
180
what are some medications that are used for pt who have an allergy to iodine?
corticosteroid (prednisone) anti histamines (benadryl)
181
what is the most common complication of IV contrast injection?
extravasation- leakage of contrast outside the vessel
182
what can the pt experience when there is extravasation?
swelling burning tightness
183
what do you do if there is extravasation present?
inform radiologist elevate the extremity hot and cold compress
184
what are some common allergic reactions to contrast (mild)
scattered hives pruritus rhinorrhea coughing
185
what do you do if a pt is experiencing a mild reaction?
monitor 20-30 mins monitor vital signs antihistamines
186
what are examples of a moderate reaction?
diffuse hives persistent vomiting laryngeal edema tachycardia
187
what do you do if a pt is experiencing a moderate reaction?
monitor pt vital signs IV access antihistamines
188
what are examples of a severe reaction?
altered mental status pulmonary edema laryngeal edema tachycardia
189
what do you do if a pt is experiencing a severe reaction?
code blue epinephrine
190
what is nephrotoxicity?
decrease in renal function following contrast administration risk is increased if there are past renal issues
191
what drug is administered to a pt who is experiencing an allergic reaction to iodinated contrast?
diphenhydramine
192
why is barium a common contrast agent?
high atomic number (56) allows for a higher attenuation
193
is barium sulfate water soluble?
No
194
what is it called when barium is introduced into the GI tract?
enteral
195
what is it called when barium is introduced outside the GI tract?
parenteral intrathecal intra-articular intravenous
196
is barium sulfate water safe for parenteral injections?
no
197
what do you do if there is a perforated bowel in the GI tract?
do not use barium only use water-soluble iodinated contrast
198
what is the CR for RAO sternum?
center at T7 and 1 inch from the midsagittal plane
199
what is the recommended SID for an RAO view of the sternum?
30 inches
200
how much rotation is needed for an RAO view of the sternum?
15-20 degrees
201
in a ribs series for a PA view where do you pout the affected side?
place anterior injuries or affected side close to the IR
202
What is the SID for a rib series?
40 inches
203
what is the CR for AP lower ribs?
on the midsagittal plane midway between the xiphoid process and the lower rib margin
204
what ribs need to be included in the lower rib view?
ribs 8-12
205
what ribs need to be included in the upper rib view?
ribs 1-10
206
what is the SID for oblique upper ribs?
72 inches
207
what is the CR for oblique upper ribs?
midway between the jugular notch and xiphoid process then move towards the lateral side in question
208
what is the purpose of doing oblique ribs?
shows the posterior portion
209
what is the appropriate placement of the top of the IR for an AP above ribs?
1.5-2 inches above the shoulder
210
which two views of the following would best demonstrate a pt who is experiencing left anterior rib pain?
PA of the affected side RAO
211
what needs to be demonstrated on a diagnostic AP KUB
lower diaphragm pubic symphysis soft tissue anatomy within the abdominal cavity
212
For AP upright KUB how is the midsaggittal plane positioned?
perpendicular to the IR
213
what is a diagnostic dorsal decubitus KUB?
free of motion superimposed ilia lumbar vertebrae pedicles and open intervertebral foramina
214
what is the CR for dorsal decubitus KUB?
2 inches above the crest
215
when performing a decubitus KUB why do you need to place the pt on a radiolucent pad? (PT is a on a stretcher)
elevates the pt off the stretcher or x-ray table. Ensures that the side down is included in the radiograph
216
why are KUBs ordered?
tube and line placement abdominal pain kidney stones
217
what is the most distal portion of the small bowel?
ileum
218
which quadrant is the gallbladder found in?
RUQ
219
which organ is positioned transversely across the upper abdomen?
pancreas
220
what is a series circuit?
a circuit where all the lines are connected end to end in a line
221
What is the difference between a series and a parallel circuit?
series circuit has one line and the current flows in one direction and is constant but the voltage drops at each resistor. parallel circuit has multiple sections that break off from the main circuit. The current is not constant but the voltage is
222
pro of series circuits?
uses simpler wiring easier detection of faults in a circuit
223
cons of series circuits?
if one component stops working then the entire circuit stops working
224
total current forumla
1. the total current in a series current is the same as any current through any resistor I(t)=I(1)=I(2)=I(3) this is because the current flows in one direction 2. total resistance is equal to the sum of all individual resistances Rt=R1+R2+R3
225
voltage drop
voltage changes at each resistor
226
total voltage
Vt=V1+V2+V3
227
what is Ohm's law?
V(voltage)=I(current) x R(resistance)
228
the resistance of electric flow through a circuit is measured in
ohm
229
a series circuit is a circuit in which components are connected.
to the power source end to end in a line
230
in a series circuit, all resistors share what?
the total voltage of the circuit
231
in a series circuit question when it asks what is the total voltage how do you solve the problem?
multiply the Amps to each of the resistances and then add their values together
232
in a series circuit question when it asks what is the total resistance how do you solve the problem?
you just add up all the resistance
233
what is a parallel circuit?
network of electrical components each connected to the power source by a different path maintains the consistent voltage across the circuit
234
if a component fails in a parallel circuit what happens?
the circuit continues to operate but because each component is connected to the power separately
235
formula for calculating total resistance in a parallel circuit
1/rotal resistance(Rt)=1/R1 + 1/R2 + 1/R3
236
in a parallel circuit does voltage fluctuate across the circuit?
no
237
which of the following measurements remains constant in a parallel circuit?
volts
238
what is the purpose of Ohm's law?
describes the relationship between voltage, resistance, and current within an electrical current
239
what does Ohm's law state?
current is directly proportional to voltage and inversely proportional to resistance
240
what is voltage
the force that pushes electrons through a circuit
241
what is resistance
the force that slows down electrons in a circuit
242
what is current?
the rate at which electrons flow through the circuit
243
what is the voltage formula?
V= I x R
244
what is the resistance formula?
R= V/I
245
what is the current formula?
I= V/R
246
what is the relationship between current and voltage according to Ohm's law?
as current increases, voltage increases
247
what is the relationship between current and resistance according to Ohm's law?
as current increases, resistance increases
248
in a series circuit, all resistors share which of the following
the total voltage of the circuit
249
what remains constant in a series circuit
current
250
The name of the first X-ray tube?
Crookes tube
251
The modern X-ray tube is based on this type of tube.
Coolidge tube
252
leakage radiation must fall below this number
100m Roentgens /h at one meter (3.2 feet) from the tube
253
The charge of the cathode
negative
254
the charge of the anode
positive
255
the glass envelope of the X-ray tube is composed of
Pyrex glass
256
the filaments are located within
the focusing cup
257
the lowest kv setting possible for producing characteristic radiation
69 kvp
258
what is the purpose of the cathode?
creates free electrons through thermionic emission
259
what is the purpose of the anode?
absorbs electrons and creates X-rays
260
what is the purpose of the glass envelope?
creates an air-free vacuum around the cathode and anode prevents the tube from blowing up or corroding
261
what is the glass envelope made out of?
borosilicate glass (pyrex), metal, or ceramic
262
what is the purpose of the tube housing?
prevents X-rays from being emitted throughout the exam room
263
how much leakage radiation does the tube housing need to keep?
maximum (0.88 mGy/hr)
264
what is the effective limit of mA that can be used?
1000
265
what is it called when a cathode tube has 2 filaments?
dual focus
266
what is the purpose of the small filament (cathode)?
creates a tight and very narrow X-ray beam which allows for high spatial resolution small mA used on small anatomy small exposures
267
A narrow electron beam increases what?
spatial resolution
268
what are the benefits of stationary anode?
simple design used for low exposures
269
what are the cons of stationary anode?
low heat capacity
270
benefits of a rotating anode?
high heat capacity high exposures
271
what is responsible for rotating the anode?
induction motor induces the anode to spin
272
what is the induction motor composed of?
2 stators- electromagnets that help turn the rotor rotor- rotating tube shafe attached to the anode disc bearings- low friction spheres that allow for free rotation of the rotor
273
the term space charge within the X-ray tube refers to
free electrons
274
what are the two interactions that occur on the anode and are responsible for the creation of X-ray photons?
bremsstrahlung radiation and characteristic radiation
275
what is the principal advantage of using the large filament within a dual-focus X-ray tube?
increased heat capacity
276
The typical angulation of the anode is between
6 to 20 degrees
277
what is the purpose of the anode angle?
increases the surface area of the focal spot which increases the ability of the anode to absorb heat decreases focal spot size which increases spatial resolution
278
what are the cons of the anode angle?
causes a variant of the beam intensity higher intensity on the cathode side rather than the anode
279
what is the anode heel effect?
decreased x-ray beam intensity on the anode side of the beam
280
as the anode angle decreases heat dissipation
decreases
281
as the anode angle decreases the heel effect
increases
282
as the anode angle increases spatial resolution
decreases
283
as the anode angle increases the surface area
increases
284
beam intensity is greatest closer to
cathode
285
It is recommended to place the abdomen under the ________ side of the x-ray tube
cathode
286
As SID increases, the heel effect
decreases
287
As field size increases, the anode heel effect
increases
288
how can the anode heel effect be used as an advantage?
In a KUB for example place the thinnest portion of the patient under the anode side of the beam this allows for a more even exposure of the IR
289
the anode heel effect is defined as a variation in which of the following?
beam quality across the X-ray field
290
the use of an X-ray tube with a large anode angle results in
increased focal spot size heat capacity
291
the use of an X-ray tube with a large anode angle results in
decreased: focal spot size heat capacity
292
True or false the cathode side always have a higher intensity than the CR?
true
293
what is a potential negative consequence of an increased anode angle?
increased effective focal spot
294
what happens if the anode angle decreases?
effective focal spot decreases and the heel effect increases
295
what is the line focus principle?
relationship between the actual focal spot on the anode and the effective focal spot that extends from the anode
296
what does the line focus principle affect?
heat capacity, spatial resolution, and beam coverage
297
what is the actual focal spot?
located on the anode the physical area where electrons are converted into X-rays
298
what is the effective focal spot?
the width of the X-ray beam as it is projected at the patient
299
what does an effective focal spot influence?
affects the creation of penumbra and spatial resolution
300
what does a small effective focal spot allow for?
decrease penumbra increase spatial resolution
301
what are the pros of having a smaller anode angle?
very narrow effective focal spot well aligned beam high spatial resolution
302
what are the pros of having a smaller anode angle?
reduces the size of the actual which means more concentrated heat smaller exposure factors smaller field size (beam coverage)
303
when would you use a small anode angle?
extremity imaging dental mammography
304
when would you use a large anode angle?
large exposure techniques and large field size ex: spine, KUB, pelvis
305
does off-focus radiation increase patient dose?
yes because it exposes the pt outside the collimated area
306
does off-focus radiation reduce spatial resolution?
maybe processed as part of the image resulting in decreased spatial resolution caused by failure of histogram analysis
307
how would you fix off-focus radiation?
use post-shuttering to eliminate any miss exposed areas
308
how does off-focus radiation occur?
occurs when electrons collide with tube components outside of the focal spot
309
which component of the X-ray tube contains the focal spot?
anode target
310
during the histogram process, the computer may identify off-focus radiation as
values of interests
311
what areas should be shuttered? (off-focus radiation)
bright white collimator shadows
312
what does tube loading refer to?
refers to the heat created within the X-ray tube
313
what is the equation for heat units?
kvp x mAs x w w=wave form factor
314
what is the purpose of a tube rating?
refers to max exposure allows exposure factors can be safely used without overheating the tube (kvp, mAs)
315
what are the tube loading factors?
exposure time anode angle filament size anode rotation speed
316
if the exposure time was increased and the mA was decreased what happens to the heat capacity?
it increased due to the longer exposure time which gives it more time to dissipate heat
317
what is the waveform factor for a 3-phase six pulse x generator?
1.35
318
you can reduce the chance of excessive heat production and X-ray tube damage by modifying the
filament size
319
what is the purpose of the anode cooling chart?
time before taking another exposure (mAs)
320
when using a large anode angle this results in
increased focal spot (larger) increased heat capacity
321
what is contrast?
visible difference in brightness between two adjacent areas in the image
322
an image with a large number of BLACK and WHITE shades
high contrast short grayscale
323
an image with many shades of grey
low contrast long grayscale-more white or grey
324
short scale
high contrast less shades of gray
325
the material used for strips in grids
lead (most common) tungsten platinum
326
what affects image contrast?
kVp and grids (procedural factors) patient factors (size and pathology) *computer processing* post-processing monitordisplay caibraation
327
what is a part of the computer processing step?
histogram analysis lookup tables both affect contrast if values are wrong
328
which of these terms describes a radiographic image with widely varying brightness
short scale high contrast
329
which factor is the most important factor controlling image contrast in radiography
computer processing
330
what is the grayscale?
total brightness levels visible in the image
331
high contrast is defined by
short grayscale and a few shades of grey
332
low contrast is defined by
long grayscale and many shades of grey
333
which of the following might make it difficult to visualize the anatomy and pathology of the abdomen
long grayscale and many shades of grey
334
long grayscale is synonymous with
low contrast and many shades of grey
335
large visible differences in brightness are defined as
short gray scale high contrast few shades of grey
336
factors that influence image contrast
kVp OID grids filtration collimation
337
decrease OID=______________image contrast
decreased image contrast low contrast
338
high grid ratios=___________image contrast
increased high
339
increased collimation=______________image contrast
increase
340
tight collimation=_____________scatter
decrease
341
increasing exposure field=____________________image contrast
decreased
342
large exposure field=______________scatter
increase
343
decreasing kVp by 15% has what effect on image contrast?
increase image contrast
344
which is preferable in diagnostic images high or low contrast?
high contrast because it makes anatomic structures more visible
345
what are procedural factors?
variables that the technologist can control as part of the exposure
346
true or false procedural factors such as kvp, grid ratio, and collimation have more influence on image contrast
false because computer processing algorithms are good at correcting images
347
why does image contrast exist?
signal differences in the remnant beam called differential attenuation
348
high signal difference=
high contrast
349
what are the signal intensity influencing factors?
kvp grid collimation
350
when changing the kvp what does that affect in terms of image contrast?
influences signal difference in remnant beam
351
why do we use grids?
high signal difference=less scatter increased contrast
352
what is the term to describe the signal difference in the remnant beam?
differential attenuation
353
which tissue type corresponds to the highest signal intensity at the IR
bowel gas has extremely low density which means it attenuates with very little radiation
354
what is the definition of image contrast?
visible difference in adjacent brightness levels within the radiographic image
355
what is the definition of subject contrast?
magnitude of the signal difference in the remnant beam as a result of the different absorption characteristics of the tissues and structures making up the part
356
when looking at the heart on a cxr it will have a low absorption and high signal
no, it will have a high absorption due to its high density and a low signal
357
why is barium used in GI studies?
because the abdomen has uniform moderate absorption which means they have lower image and subject contrast. Barium helps highlight the anatomy.
358
A pt has a bowel obstruction How does that affect image and subject contrast?
both increase due to the large amount of air in the abdomen
359
A pt has bowel ascites (fluid in the abdomen) How does that affect image and subject contrast?
both decrease due to the large amount of liquid in the abdomen
360
when imaging a bariatric pt for a cxr what happens to the subject and image contrast?
decreases causing the image to look more washed out
361
what is the primary factor controlling subject contrast?
the absorption characteristics of the tissues and structures being exposed
362
what term describes a body section that creates a remnant beam having widely varying signal intensities
high subject contrast
363
imaging subject contrast increases the visibility of anatomy and pathology due to
increased brightness differences between adjacent structures
364
which contrast factor has the most influence on the image contrast?
digital factors
365
what is a histogram?
graphical representation of the collection of all exposure frequencies capture by detectors
366
what is a lookup table?
mathematical process that converts low-contrast raw data into high-contrast image data
367
what does window width show?
shows the contrast displayed within the image
368
what happens when the window width is increased?
increases the amount of grey within the image (less contrast)
369
what computer process adjusts raw radiographic data to create more contrast in the processed data?
lookup table application
370
which of the following is an image processing factor that influences radiographic image contrast?
histogram analysis
371
what is the definition of structural resolution?
structural sharpness recorded in the radiographic image differentiate between different anatomy in a certain area
372
what are the units for spatial resolution?
line pair per millimeter (LP/mm)
373
what affects spatial resolution?
patient factors beam geometry IR factors digital image factors digital display factors -pixel size -pixel pitch -matrix size
374
which anatomical parts can be used as an indicator of the spatial resolution recorded in a radiographic image?
trabecular bone
375
what are the patient factors?
-PT size -PT movement
376
what are the beam geometry factors?
-SID -OID -Focal spot size
377
what are the image receptor factors?
-detector element size -pitch -fill factor
378
what are the digital imaging factors?
-pixel size -matrix size
379
what are the digital display factors?
-pixel size -pixel pitch -matrix size -fill factor
380
what happens if OID is increased?
leads to lower spatial resolution which causes blurriness this is known as penumbra
381
what should you do when pt size or pathology is degrading the spatial resolution?
increase SID
382
focal spot blur formula
FSS x (OID/SOD) SOD= SID-OID
383
what is an ideal scenario for maximum spatial resolution?
large SID Small OID small effective focal spot no tube angles
384
decrease in element size would lead to
increase spatial resolution
385
what is pitch
it is the distance between one detector element to the next
386
what is the fill factor?
fraction of the del surface area that is capable of measuring incoming X-ray beams
387
which part of the X-ray beam has different signal intensities that correspond to the anatomy represented on the image IR
remnant beam
388
what does DEL stand for in digital radiography?
detector element
389
which of the following describes the detector element pitch
distance from one DEL to another
390
what is the definition of matrix size?
the number of pixels in an image
391
if the matrix size increases_______________
pixel size decrease
392
what happens to the image if there is a low receptor exposure (fewer photons hit the IR)
quantum mottle
392
what is the recommended size for monitors for routine radiography?
3MP
393
what happens to the image if there is a high receptor exposure
saturation
394
what affects receptor exposure?
prime exposure factors influencing factors
395
what are the prime exposure factors?
mA exposure time kVp SID
396
what are the influencing factors?
AEC Grids filtration collimation anode heel effect patient factors
397
if mAs is increased________________
the number of photons increases which means there will be more photons striking the IR
398
if kVp is increased how does this affect the beam?
adds more penetrability
399
15% rule
increasing kVp by 15% will double receptor exposure
400
a technologist can identify an image with excessively high mAs based on
an exposure indicator outside of the acceptable range
401
if the angle of the tube is increased how does that affect the anode heel effect?
decreases it
402
magnification is the consequence of the
divergent beam
403
factors that affect magnification
OID SID SOD
404
magnification factor formula
SID/SOD tells us the actual size of the object-based image on the radiograph
405
what are the two types of shape distortion?
foreshortening elongation
406
how does foreshortening occur?
when the anatomy is not parallel with the IR
407
how does elongation occur?
tube and receptor are not perpendicular to each other
408
law of isometry
central ray should be set at half of the angle formed between the object and IR
409
what projection has foreshortening
lordotic chest
410
an increase in tube potential would increase receptor exposure by increasing which two of the following?
penetrating ability of the beam number of photons in the beam
411
what is most likely the adverse effect of processing an image under the wrong anatomic part?
incorrect image contrast
412
what term describes the light-emitting components within display monitors?
picture element (pixel)
413
what computer processing features influence radiographic image contrast?
histogram analysis look up table
414
what is referred to as size distortion?
magnification
415
how does increased kvp affect differential attenuation of the X-ray beam
decreased differential attenuation
416
large signal differences in the remnant beam will produce a radiographic image demonstrating
high image contrast
417
how does increasing window width affect the displayed image?
decreased contrast
418
receptor exposure is affected by
generators collimation filtration
419
the distance between the anatomy being imaged and the focal spot within the X-ray tube is called
source to object distance
420
when the anatomy being imaged is PARALLEL to the IR and the beam is angled what type of shape distortion is this?
elongation
421
the term used to describe signal differences in the remnant beam
differential attenuation
422
matrix size increases______________________
increased spatial resolution
423
matrix size increases the size of the pixels_________________
increase
424
grayscale
the total brightness levels that are visible in an image
425
what post-processing factor affects image contrast?
window width
426
what is the CR for AP thumb?
1st MCP joint
427
for PA hand the pts arm should be bent ______________________
90 degrees
428
Coyle method for the coronoid process
Entering the joint at mid-elbow at a 45° angle towards the coronoid process the tube is positioned above pt 80 degree elbow bend
429
Coyle method for radial head
Entering the joint at mid-elbow at a 45° angle towards the radial head tube in front of pt 90 degree elbow bend
430
CR for transthoracic humerus
Injured humerus against the image receptor Perpendicular to the image receptor Level of the surgical neck Mid-coronal plane centered to the midline of the image receptor
431
for transthoracic humerus what must be seen in the lungfield
proximal humerus greater tubercle in profile
432
What is ALARA?
as low as reasoning achievable time distance shielding
433
what is the primary source of occupational dose?
the pt
434
why is lead used for shielding?
high atomic number high mass density high attenuation
435
what is used to measure shielding?
half-value layers
436
what lead thickness equivalence is required for protective lead aprons in surgery, general radiography, and fluoroscopy?
0.50mm lead
437
lead thickness for glasses
0.35mm lead
438
lead thickness for gloves
0.25mm lead
439
lead thickness for bucky slot
0.25mm lead
440
what does positive beam limitation do?
automatically adjusts collimation to adjust to detector size
441
use of lead to reduce the exposure field size has what effect on radiographic image quality?
increase image contrast
441
what material are the collimator blades made out of?
lead
442
positive beam limitation is a safety feature that ensures the size of the X-ray field is no larger than
the detector dimensions
443
the component of the X-ray assembly that is manipulated by the operator to precisely define the size of the X-ray field
adjustable collimation
444
the primary benefit of collimating the exposure field size to the required anatomy is
decrease in pt effective dose
445
entrance skin dose
photons that do not have enough energy to penetrate the pt which are then absorbed in the pt's skin
446
what is the most common filtration material?
aluminum gets rid of low-energy photons
447
why is aluminum used for filtration?
low atomic number absorbs most low-energy photons allows transmission of most high-energy photons
448
inherent filtration
results from the construction of the tube itself and filters the x-ray beam glass envelope insulating oil window mirror
449
inherent + added filtration=
total filtration
450
what is added filtration?
anything added to the X-ray machine ex: aluminum
451
what is the minimum thickness of diagnostic filtration for x-ray tubes operating above 70kvp
2.5mm Al eq
452
the thickness of inherent filtration for general x-ray tube assemble is equal to
0.5mm AL eq
453
the thickness of added filtration for general x-ray tube assemble is equal to
2mm AL eq
454
how does decreasing filtration thickness affect the quantity of the beam
increased quantity
455
What is the CR for external rotation of the shoulder?
1 inch inferior to the coracoid process or 1 inch of light above the shoulder
456
What is seen in profile when performing external rotation of the shoulder?
Greater tubercle
457
What is seen in profile for a internal rotation of the shoulder?
Lesser tubercle
458
How is the hand position for an AP neutral view of the shoulder?
It is the palm of the hand is on the hip
459
How is the pt positioning for the Lawrence view?
Pt is spine Affected arm is abducted (sticking out) and externally rotated resting on a sponge CR enters the axila Tube is turned 30 degrees to the table IR and tube are parallel to each other
460
What is the purpose of doing the inferosuperior axial or Lawrence method (shoulder)
Demonstrates the relationship of the lateral humerus to the Scapulohumeral joint.
461
When performing the shoulder Y view where is the CR
Scapulohumeral joint
462
How do you position AP scapula?
40 SID CR: 2 inches inferior to the coracoid process or put the top of the light field 2 inches above the shoulder Place arm above arm to remove scapula from ribs Exposed on slow respiration
463
How is lateral scapula positioned?
Affected side against IR CR at medial aspect of scapula If affected arm is placed behind back supinated=coracoid and acromion Across chest= body of scapula
464
Appropriate criteria for a lateral view of scapula
Scapular body free of rib superimposition Humerus does not superimpose area of interest
465
Why must a pt arm be abducted 90 degrees for AP scapula
Moves the scapula laterally to minimize superimposition of ribs
466
What is the breathing technique for AP clavicle?
Taken on expiration
467
What is the angle for AP axial clavicle?
15-30 degrees cephalad
468
What is the breathing technique for AP axial clavicle?
Inspiration
469
What is the SID for bilateral AC joints?
72 inches
470
What is the CR for bilateral AC joints?
CR is at the jugular notch
471
For weighed AC joints what breathing technique is used?
Exposed on expiration
472
What cassette size do you use for bilateral AC joints?
17x14
473
What breathing technique is used for AP external rotation of the shoulder
Suspend respiration
474
For AP hip why do we invert the pt feet?
Elongates the neck of the femur and puts the greater trochanter in profile
475
Where is the CR for unilateral frog leg hip?
Midway between the ASIS and pubic symphysis
476
What is the tube angle for danielus miller method
15 degrees posteriorly perpendicular to femoral neck
477
Positioning for AP axial anterior pelvis outlet view
Cepahilic angle: 20-35 men, 30-45 female CR:1-2 inches distal to the superior border of pubic symphysis
478
Positioning for pelvis inlet view
40 degree cuadal CR: at ASIS
479
what anatomic structures should be included in an AP axial outlet projection Taylor method?
pubic and ischial bones magnified with pubic bones superimposed over the sacrum and coccyx
480
what anatomy needs to be seen on the superior inferior axial inlet projection Bridgman method?
superimposed superior and inferior rami of the pubic bones and anterior pelvic bones
481
what are the requirements for x-ray production?
source of electrons acceleratation of electrons deceleration of electrons
482
where are the electrons produced in the tube?
the filament (cathode)
483
how are the electrons accelerated?
an electron voltage (kVp) is applied and causes a strong negative charge moving the electrons to the anode side
484
how are the electrons decelerated?
they strike the anode and release heat and X-ray
485
an increase in mA increases the number of ________________ and the number of _____________
electrons and photons
486
an increase in kVp increases the of ________________ and increases _____________
the energy of electrons and x-ray energy
487
true or false exposure time increases then the number of X-ray photons
true
488
what is the definition of exposure time?
the amount of time that the electrons are flowing through the tube and the x-rays are being created
489
the term of electron production
thermionic emission
490
what is the charge of the filament?
negative
491
the measurement of tube current
mA
492
the controller of X-ray intensity (quantity)
mAs
493
the controller of photon penetrability (energy)
kVp
494
what condition is required to induce thermionic emission within the cathode filament?
high current
495
when imaging an obese patient what technical factor needs to be increased?
kVp
496
a chest x-ray demonstrates excessive exposure. How do you decrease the intensity of the beam while maintaining the same beam energy?
decrease mA
497
brem radiation is produced
by slowing of an incident electron
498
the inner shell of an atom
k-shell
499
brem radiation involves
an incident electron and the nucleus of an atom
500
a brem photon is the result of
energy difference between the incident electron as it passes near the nucleus
501
the closer the incident electron passes to the nucleus
the higher the energy of the brem photon
502
how does brems radiation start?
high energy electrons interact with the nucleus of the tungsten atom
503
bremsstrahlung radiation is created within the X-ray tube when high-energy electrons interact with
electric field of the nucleus
504
the maximum energy of bremsstrahlung photon that can created during an x-ray exposure is equal to
the energy of the incident photon
505
the maximum amount of energy of bremsstrahlung photon is controlled by which technical factor
tube potential
506
the energy of the bremsstrahlung x-ray photon is equal to the
difference between the incoming and outgoing electron energy
507
the closer to the electron is to the nucleus
the stronger the binding energy
508
a characteristic X-ray can be defined as
total removal of an electron
509
Characteristic X-ray production involves
incident electron and inner shell of the electron
510
cascade effect
movement of an electron from an outer shell into an inner shell
511
the binding energy and unit of a tungsten atom's inner shell
69 kEV
512
lowest kv setting possible for producing characteristic radiation
69 kVp
513
what technical factor is primarily responsible for controlling the energy of the x-ray beam
mA
514
what is the definition of attenuation?
a reduction in the x-ray beam intensity as a result of absorption and scatter in matter
515
what are the 3 x-ray interactions with matter?
transmission absorbed scattered
516
what does intensity refer to?
the number of x-ray photons
517
after the primary beam has interacted with the patient what is the x-ray beam called?
remnant beam
518
what are the 3 attenuation reactions?
photoelectric coherent scattering compton scattering
519
what does attenuation mean?
a reduction in the x-ray beam intensity as a result of absorption and scatter in matter
520
photoelectric absorption
then use of ionization to remove an electron in the inner shell and bring a photon in
521
coherent scattering
x-ray photon enters then is absorbed by the ENTIRE atom then the energy of photon is released in a different direction
522
Compton scattering
x-ray photon enters and is partially absorbed by outer electron and ionization takes place. Then remaining energy of the photon is released in a different direction
523
amount of attenuation is dependent on
part thickness tissue density atomic number beam energy
524
an increase in anatomy thickness leads to increased_________________
attenuation
525
which radiographic projection results in the highest percentage of x-ray attenuation?
pelvis because it has more bone
526
true or false: coherent scattering does have an effect on pt dose?
false no ionization no biological harm
527
true or false: coherent scattering does have an effect on occupational dose dose?
false scatter is directed toward IR
528
how does coherent scatter affect the image?
creates scatter decreases contrast in the image
529
when does coherent scattering occur?
when there is low photon energy least likely
530
true or false: photoelectric absorption does have an effect on pt dose dose?
true ionization-damaging
531
true or false: photoelectric absorption does have an effect on occupational dose dose?
false no scatter
532
true or false: photoelectric absorption does have an effect on image quality?
good effect because it creates contrast
533
what are the two products of PE interaction?
free electron characteristic photon
534
how does increasing kVp affect the proportion of photoelectric absorption events that occur in pt tissues?
increasing kvp decreases the proportion of PE absorption
535
what the products of Compton scattering?
free electron scattered photon
536
what is the product of coherent scattering?
scattered photon
537
true or false: Compton scattering is a benefit to pt, occupational dose, and image quality
false due to the ionization and the end product of scatter leads to an increase in exposure to both the pt and healthcare worker
538
more matter means____________
more scatter
539
how to reduce Compton scatter
decrease part thickness use smallest field size collimate Use lower kVp
540
when imaging AP toes how much of an angle do you add to view the joint spaces?
15 cephalad
541
where do you center for an oblique toe?
MTP joint
542
how do you position for a lateral toe?
have the pt position like a lateral foot and then use tape to pull the toe in question outwards
543
how do you position tangential view of the toes?
wrap tape around pt toes and have them pull toes backwards. CR at first metastarsal
544
what is the recommended collimation for the tangential projection of sesamoids
1-2 inches on either side of the foot
545
positioning parameters for plantodorsal view of the calcaneus?
40 degree cephalic angle CR to the base of the third metatarsal dorsiflex foot
546
why is there a tube angle for AP foot?
to be perpendicular to the metatarsal joint space
547
why do we internally rotate 30 degrees for medial oblique foot?
to reduce superimposition of the cuboid
548
how much do you angle for AP knee
3-5 degrees caudal if ASIS measurement is greater than 19cm no angulation 19-24cm 3-5 cephalad measurement of 24cm of less
549
what is the CR for lateral knee?
1 inch inferior to the lateral epicondyle of the femur angle tube 15-20 degrees
550
tangential settlegast view Knee
patient is positioned like a sunrise tube matches angle of the IR (upwards) CR at the knee joint
551
for the tunnel view of the knee how much should the knee be flexed?
40-60 degrees
552
for AP proximal femur how should the IR be placed?
top of the IR at the level of ASIS
553
lateral distal femur how should the IR be placed?
bottom of IR 2 inches distal to the patellar apex
554
x-ray photon
lots of energy no mass no charge travels at the speed of light
555
what is wavelength?
measure of one peak to the next
556
true or false a decreased in wavelength results in an increase in crease frequency with means more energy
true
557
what units are used for frequency?
hertz
558
the x-ray beam is composed of one singular energy source
false because it is polyenergetic
559
what does the term quality refer to
average energy of x-rays
560
true or false x-ray beams travel out of the tube in all directions
true it is isotropic
561
electromagnetic spectrum
full range of photon energies
562
what is frequency
number of wave cycles per second
563
tube current refers to
flow rate of electrons
564
exposure time refers to
total amount of time that electrons are flowing
565
a tech is attempting to increase the x-ray beam intensity without modifying the overall energy of the x-ray beam they should
increase mA will increase the the quantity of photons but it won't affect the overall energy of the x-ray beam
566
a tech is attempting to decrease the beam intensity and decrease the penetrability of the beam they should
decrease kVp
567
true or false if distance is increased then the beam quantity decreases
false
568
all technical modifications that will increase the beam quantity
increase mA increase time increase kVp decrease distance decrease filtration
569
decreasing SID will result in
increased concentration of photons
570
beam energy is measured in
Kev kiloelectron volt
571
beam quality is influenced by
kVp beam filtration
572
which of the following will add to the pt dose but not to diagnostic quality of the image
low energy photons
573
In a fluoro exam where is the x-ray tube positioned?
behind the pt
574
When using a C-arm when should the backwards R button be used
pt is prone looking away from the smiley face indicator
575
true or false pediatric fluoro is a sub category of conventional fluoro
true
576
what are the components of the IR in fluroro?
input phosphor photocathode focusing lenses electrostatic anode output phosphor
577
what is the input phosphor composed of?
cesium iodide
578
what is the purpose of cesium iodide
helps improve spatial resolution of the image
579
what is the purpose of electrostatic focusing lenses of a fluoro tube?
helps funnel the photoelectrons into a concentrated stream
580
what is the output phosphor of the fluoro tube made out of?
zinc cadmium sulfide
581
what is flux gain?
kinetic energy gained during acceleration from photocathode to output phosphor
582
minification gain
concentration of photoelectrons from the input phosphor to the output phosphor
583
what is the flow of energy conversions in fluoro
1.digital signal 2. analog signal 3. light photons 4. photo electrons 5. light photons 6.x-rays
584
what happens at the input phosphor?
x-ray photons are converted into light photons
585
what happens at the photocathode
light photons>>>>photoelectrons
586
what does the electrostatic lenses do?
focus photoelectrons to anode
587
what does the output phosphor do>
photoelectrons>>>light electrons
588
what is the purpose of the IR in fluoro imaging?
brightens the fluoroscopic image so that it can be of diagnostic value
589
what is the role of the anti scatter grid on the IR of the fluoro tube
increase image contrast
590
which component collects light photons from the output phosphor and converts them to electrons?
charge coupled device
591
what kind of grids does interventional radiology?
crossed hatched grid
592
why does fluoro use a lower grid ratio (less space in between)
uses higher kVP to penetrate contrast and lower mA to limit overexposure
593
where is the grid located in a fluoro tube?
in front of the input phosphor
594
brightness gain
measure of the ability of the image intensifier to increase the brightness level of them image
595
conversion factor
percentage that measures the efficiency of the image intensifier
596
formula for flux gain
output light photons/input x-ray photons
597
minification gain formula
D^2i/D^2o i=input phosphor o=output phosphor D=diameter
598
brightness gain formula
flux gain x minification gain
599
conversion factor formula
intensity of light at the output phosphor/intensity of radiation at the input phosphor
600
during a fluoro exam what is the purpose of automatic brightness control?
adjusts exposure factors to deliver constant signal intensity to the image receptor
601
vignetting
decrease in image brightness around the edges of the image due to large OID
602
how is vignetting fixed?
image processing adjusting image intensifier reduce OID
603
pincushioning
parts of the image appear curved or bent inward towards the center of the image caused my external magnetic fields
604
how is pin cushioning fixed?
post processing
605
the components of flat panel detector
scintillation photodiode thin film transistor
606
what is RIS
radiology information system is like cerner and allows them to generate accession numbers
607
what is HIS
hospital information system manages operational and healthcare data
608
DICOM
digital imaging and communications medicine is universal language to exchange medical information
609
MIMPS
medical image management and processing system functions like PACS
610
components of a CR cassette
2 protective layers photostimulable phosphor- store and release energy conductive- increases spatial resolution by absorbing light support reflective
611
raster pattern
related to the processing of CR cassette mirror and image plate rapid back and fourth pattern
612
components of DR IR
photoconductor Thin film transistor ADC
613
indirect conversion DR systems
x rays visible light electronic signals
614
direct conversion DR systems
x-rays to electronic signal
615
what is the purpose of a TFT in DR
after the light photons are converted to electrical signal from the photodiode the electrical signal is then sent to ADC
616
formula for pixel size
field of view/matrix size
617
bit depth
total # of possible brightness levels that can be assigned to any given pixel in the digital image
618
quantiziation
process of assigning brightness levels
619
modulation transfer function
measures the accuracy of the image compared to the actual object measures spatial resolution
620
dynamic range
range of exposures that can be captured by an IR
621
exposure latitude
range of exposures that produces quality images at an appropriate patient dose
622
detective quantum efficiency
a score that describes the ability of the imaging system to convert the remnant x-ray beam into a high quality image
623
capture efficiency
percentage of photons that get absorbed by the detector chin to chest
624
what is the purpose of flexing for the C-spine
opens up the space between the spinous process
625
what is the purpose of extension for C-spine
closes spaces between the spinous processes
626
true or false when performing flexion of C-spine you do not need the body of the mandible
false
627
what is the SID for swimmers view?
40
628
what is the CR for swimmers view?
C7
629
what SID is used when performing a x-table spine
72
630
what is the CR for AP T spine
halfway between the jugular notch and the xiphoid process aligned with the midsagittal plane
631
what is the CR for lateral T spine
T7-arm pit level make sure to have 1.5 inches above the shoulder
632
what is the CR for L5S1
1.5 inches inferior crest 2 inches posterior to ASIS
633
what is the CR for lateral coccyx
3.5 inches posterior from ASIS and 2 inches inferior from ASIS
634
what is CR for SI joints AP
2.5 inches inferior to ASIS 30 Cephalad tube angle
635
what is the CR for oblique SI joints
At ASIS and go 1 inch medial
636
obliquity for SI joints
25-30 degrees
637
CR for oblique L spine
1.5 inches superior of crest and 2 inches medial from ASIS
638
stochastic effects
Ex: cancer random and unpredictable probability increases as the dose increases but not the severity AKA non threshold dose
639
deterministic effects
cataracts, epilation, ,diminished sperm count only occur when specific dose thresholds are reached severity of illness increases with the dose
640
dose for decreased sperm count
150 mGy
641
dose for epilation
3000 mGy
642
true or false? cancer be caused by any dose of radation
true
643
what is the chief biological cause of radiation?
Ionization
644
target theory
adverse radiation effects are only observed when sensitive target molecules in the cells are affected
645
what is direct action?
it is when x-ray photon or free electron interacts differently with DNA RARE
646
what is indirect action?
AKA radiolysis x-ray photon interacts with water which breaks into ions that can cause biological damage
647
double strand breaks
are difficult to repair low probability of completely fixing
648
how are double stand breaks caused
indirect action
649
what are the 3 forms of DNA damage
base pair lesion single strand breaks double strand breaks
650
what is the product of indirect action?
free radicals
651
early effects
manifests soon after exposure
652
examples of early effects
skin burns hair loss diminished sperm count AKA deterministic effects
653
skin erythema occurs
2 Gy or more
654
late effects
manifests after years of exposure delayed effects
655
late effects examples
cataracts and cancer
656
latency period
period of time between exposure and when symptoms start occuring
657
true or false late effects are considered deterministic
true
658
why doesn't ARS occur in diagnostic imaging?
the entire body needs to be exposed to a very high dose of radiation
659
hematopoietic syndrome occurs at
at least 1 Gy
660
Gi syndrome occurs at
at least 10 Gy
661
cerebrovascular syndrome occurs at
at least 50 Gy
662
hematopoietic syndrome
inadequate blood cell production/destruction of bone marrow
663
GI syndrome
destruction of GI tract pt often die of dehydration and electrolyte balance
664
cerebrovascular syndrome
damage to the cerebrovascular structures of the brain
665
prodromal phase
body's initial reaction to high doses of radiation exposure
666
latent phase
initial illness appears to resolve inverse related to the dose
667
manifest illness
full onset of systemic illness directly related to dose
668
what is used to determine how often pt die from ARS
LD50/60 lethal dose of radiation that kills 50% of the population within 60 days
669
what are the four stages of disease progression
prodromal latent manifest recovery/death
670
law of bergonie and tibondeau
the most radiosensitive cells are: immature unspecialized rapidly dividing
671
in the fetal cycle which part of the cycle is the most radiosensitive
pre implantation stage 100 mGy
672
physical malformations tend to develop in which part of the fetal cycle
organogensis
673
cerebral effects tend to occur in which part of the fetal cycle
fetal period
674
variables that affect radiosensitivity
age tissue type gender type of radiation rate of exposure
675
tissue radiosensitivity is important when determining which form of measurement
effective dose
676
densely ionizing
high LET deposits energy within a shorter distance causes more damage
677
oxygen enhancement ratio
the difference in biological harm for each radiation type
678
which type of cell is the most radiosensitive?
hypoxic cells
679
fractionation
tumor is exposed to numerous small doses rather than one large dose
680
what is the OER of x-ray
3x
681
LET is commonly measured in units of
kiloelectron volts/micrometer
682
relative biological effectiveness
radiations ability or effectiveness in causing biological damage
683
What happens if the image is underexposed?
Mottle Grainy image Increase kVp and mAs
684
Receptor exposure
The amount of radiation striking the receptor
685
Exposure indicator
Numerical expression of the receptor exposure
686
the process that converts original radiographic histogram to the expected histogram
rescaling
687
the process that identifies the values of interest in a radiographic histogram
histogram analysis
688
the process of adding brightness and contrast to exposure values within a radiographic range
look up table conversion
689
the lowest readings on a histogram represent
collimated tissue
690
coincidence testing assess
light field accuracy
691
actual exposure time must be within_______of the indicated exposure time
5%
692
the actual kVp must be within ___________ of the assigned kVp
5%
693
the light field must correspond to the actual exposure field with the tolerance of
2%
694
mGy/mAs measurement between adjacent mA stations should not vary by more than `
10%
695
x-ray systems must demonstrate consistent exposure reproducibility within a tolerance of
2%
696
the CR indicator must align to the actual center of the x-ray field within the tolerance of
1%
697
SID range should be
2%
698
exposure linearity error range
10%
699
positioning parameters for lateral skull
anterior oblique CR: 2 inches above EAM IPL perpendicular to the edge of the IR
700
what makes a diagnostic lateral skull x-ray
superimposition of the orbital roofs and greater sphenoid wings sella turcica in profile
701
what makes a diagnostic PA skull
symmetric petrous ridges orbits filled by petrous ridges
702
postponing parameters for AP Townes skull
30 degrees caudal 2.5 inches above glabella OML is perpendicular
703
positioning for AP Townes skull if pt can't bend chin
bend chin put 37 tube angle and use IOML
704
diagnostic PA caldwell skull
petrous pyramids sitting at the lower 1/3 portion of the orbit
705
positioning parameters for SMV skull
IOML is parallel to the IR CR: 0.75 inches anterior to EAM
706
for SMV skull the CR should enter where?
sella turcica
707
positioning parameters for lateral facial bones
Anterior oblique IPL perpendicular to IR mid sagittal plane is plane to IR CR: between the EAM and outer canthus
708
diagnostic lateral facial bones
superimposed mandibular rami and oribital roofs sella turcica in profile
709
for waters (pariteocanthial) facial bones how much of angle does the OML make?
37 degrees
710
diagnostic lateral facial bones
petrous ridges below maxillary sinus
711
for facial bones waters the OML forms what angle to the IR
55 degrees is the only one that has this
712
positioning for lateral nasal bones
anterior oblique IPL is perpendicular IOML perpendicular to front edge of IR CR: 0.5 inch inferior to nasion
713
CR for lateral sinus
midway between outer canthus and EAM
714
what 2 sinuses are shown on an SMV
sphenoid and ethmoid
715
what 2 sinuses are shown on a waters
sphenoid and maxillary
716
millamperage formula
mA x s= mAs
717
Ma in the x-ray tube is the unit of measure describing
tube current
718
exposure time
electrons are flowing through the tube
719
in order to decrease motion blur on an image what should you do?
decrease mA and increase exposure time
720
SID is defined as the distance from the
anode focal spot to the IR
721
mA in the x-ray tube is the measurement of
tube current
722
AEC
provides x-rays with consistent receptor exposure automatically adjusts exposure time reduces the chance of over exposing pts
723
what do ionization chambers do?
measure receptor exposure
723
true or false AEC controls the mAs
true
724
when using AEC what does the tech need to adjust
SID kVp mA
725
to change the receptor exposure for the chambers what do you need to do?
adjust the density setting
726
if there is motion in the radiograph how do you fix it?
increase mA and lower exposure time
727
when using a grid what technical factor needs to be increased?
mAs in order to maintain appropriate receptor exposure
728
grid conversion formula
mAs2= mAs1 x GCF2/GCF1 GCF2 is the new grid conversion factor GCF1 is the old grid conversion factor
729
when should grids be used?
when the atomic body part exceeds 10cm in thickness
730
grid ratio
Height of lead strips (h) divided by distance (D). h/D
731
Increase in grid ratio
Increase in image contrast Increase in needed mAs value Increase in patient dose
732
Material used for strips in grid
Lead (most common) Tungsten Platnium
733
using the incorrect SID with a focused grid results in
grid cut off because focused grids are designed to be used with specific SID
734
if you angle the tube which type of grid can not be used
crossed because the body part must be perfectly positioned
735
off level grid error
grid is not perpendicular to CR lead strips are not in line with path of useful beam
736
off level grid errors affect:
focused and non focused grids
737
off center grid error
only affects focused grids grid is not placed directly under the CR
738
off focus grid error
SID does not match the design of the focused grid only affects focused grids
739
off angulation grid error
x-ray beam is angled against the direction of the grid lines affects focused and non focused grids
740
upside down grid error
focused grid is placed upside down only affects focused grids
741
inverse square law defines the relationship between
distance and beam intensity
742
off center grid errors result in
decreased receptor exposure across the entire radiograph
743
autonomy
Patients have the right to make decisions about their healthcare
744
tort
A civil wrong that can result in legal liability
745
who is required to wear a personal dosimeter
anyone who is exposed to a dose exceeding an occupational dose of 5 mSv
746
positive beam limitation
Automatically adjusts the collimation to match the detector size
747
what material is used within collimator blades
lead
748
what is the most common material used for filters
aluminum
749
why is alluminum used for filtration
Relatively low automatic number Absorbs low-energy electrons Allows transmission of most high-energy photons
750
electronic intensificaiton
electrons are moved at a highspeed from photocathode to the output phosphor
751
the transformer core is made out of
iron due to its ferromagnetic properties
752
decrease in anode angles result in
lowest x-ray beam intensity better spatial resolution
753
what area of the x-ray tube is struct by electrons during x-ray exposure
actual focal spot
754
in DR thin film transistors do what?
collect electrical charge
755
poor IR exposure in a digital image results in
loss of information in the image
756
what is saturation of an image?
loss of information of an image due to overexposure image has no shades of grey (black)
757
what does quantum mottle look like on an image
image has a grainy texture underexposure
758
exposure latitude
range of exposures that produces quality images at an appropriate patient dose
759
purpose of ADC in CR
convert electrical signals into binary signals
760
what increases the severity of the anode heel effect
decrease SID when the anode heel degree is lessened increase field size
761
large detector element pitch results in
low spatial resolution
762
what is pitch
the distance between detector elements
763
veil glare
fall off in brightness at the periphery of an image intensifier image
764
vignetting
fall off in brightness at the periphery of an image
765
components of a transformer
core primary coil secondary coil
766
purpose of a rectifier
alternating current to direct current
767
which of the following will determine the average pixel value
region of interest
768
what is histogram anaylsis
the process used to identify the usual exposure values in the digital image
769
what do changes in SID affect?
size
770
electronic masking
elimination of extraneous light from the edges of a digital radiographic image
771
what changes are used to improve spatial resolution of an image
decreased focal spot size decreased OID increased SID
772
what is a focal spot?
is the area of the anode surface which receives the beam of electrons from the cathode. It is the apparent source of x-rays.
773
which two radiation interactions with matter will not result in ionization?
coherent scattering transmission
774
what conditions are considered somatic effects of radiation?
cataracts cancer fetal effects
775
the majority of x-ray photons in an x-ray beam are produced by
bremsstrahlung radiation
776
the primary barriers in an x-ray room must have the thickness of
1/16 or 1.6mm lead
777
who is required to wear a dosimeter
anyone who may be exposed to an annual occupational dose of 5 mSv
778
a 0.25mm lead apron will attenuate what percentage of the beam at 75 kVp?
66%
779
a 0.25mm lead apron will attenuate what percentage of the beam at 50 kVp?
97%
780
a 0.25mm lead apron will attenuate what percentage of the beam at 100 kVp?
51%
781
a 0.5mm lead apron will attenuate what percentage of the beam at 75 kVp?
88%
782
a 0.5mm lead apron will attenuate what percentage of the beam at 50 kVp?
99%
783
a 0.5mm lead apron will attenuate what percentage of the beam at 100 kVp?
75%
784
exposure maintenance formula
mAs2= mAs1 x (D2)^2/(D1)^2
785
if SID is doubled intensity is ___________
decreased four times
786
if distance is halved intensity _________________
increases 4 times
787
if mAs are double mAs must _______________
increase 4 times
788
if mAs is halved mAs must______________
decrease by a factor of 4 times
789
what controls contrast resolution
bit depth number of bits per pixel
790
subject contrast
the remnant beam after interacting with the patient
791
Nyquist frequency
highest spatial resolution that can be recorded, controlled by pixel pitch
792
rheostat
regulates thermionic emission
793
what is the thin film transistor made out of
cesium iodide
794
what is the purpose of the scintillation layer in indirect conversion
converts x-ray photons to light
795
what is the purpose of the photodiode in indirect conversion?
converts light into electrical charge composed of amorphous silicon
796
what is the purpose of the TFT layer in indirect conversion
comprised of small detector elements that capture the electrical charge and convert it into an image
797
for direct conversion what material is used?
amorphous selenium
798
QC test: filtration
annually tolerance: 2.5mm AL
799
QC test: collimation
semi-annually tolerance: 2% of SID
800
QC test: focal spot
annually tolerance: 50%
801
QC test: kVp
annually tolerance: 10%
802
QC test: timer
annually tolerance: 5% (10ms)
803
QC test: exposure linearity
annually tolerance: 10%
804
QC test: exposure reproducibility
annually tolerance: 5%
805
QC test: focal spot equipment
slit camera star test pinhole
806
QC test: exposure linearity equipment
step wedge dosimeter
807
sampling frequency (CR)
performed by laser number of times data is recorded on a digital plate when being read fast sampling frequency----small pixel pitch----increased spatial resolution
808
duodenal bulb hypersthenic
T11 or T12
809
duodenal bulb shtenic
L1 or L2
810
Aesthenic or hypersthenic
L3 or L4
811
secondary barrier lead
1/32mm Lead
812
personal dosimetry tracks radiation dose to occupational workers
exceed 10% of annual limit must wear dosimeter
813
Sthenic pt duodenal bulb location
T2-L1
814
Sthenic pt stomach location
T11-L2
815
Hypersthenic stomach location
T9-T12
816
Hypersthenic duodenal bulb location
T11-T12
817
Hyposthenic and aesthetic duodenal bulb location
T11-L5
818
Hyposthenic and aesthetic stomach bulb location
L3-L4

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