Section 3 Exam Flashcards
(81 cards)
1
Q
what percentage of the energy from the tube is released as heat and as x-rays?
A
99% heat, 1% x-rays
2
Q
what spins in the x-ray tube?
A
anode
3
Q
why does the tube have to be vacuum sealed?
A
so electrons don’t interact with air molecules and lose energy
4
Q
Human body consists of six radiographic densities (listed least to most dense)
A
Gas or air
Fat
Water
Muscle
Bone
Tooth enamel
Metal
5
Q
Cathode ____ __ to release _________ to hit spinning _____ to release x-ray
A
heats up, electrons, anode
6
Q
Computed radiography makes use of?
A
photostimulable phosphor
7
Q
X-ray beam collimation is used why?
A
pt dose is decreased, scatter dose is decreased, increases quality of image (all of the above)
8
Q
focal spot is directly related to ______
A
detail
9
Q
small focal spot =
A
sharper lines
10
Q
Do grids help with detail?
A
yes it improves detail and absorbs scatter radiation
11
Q
Greater SID =
A
increased detail
12
Q
Lower OID =
A
reduced magnification
13
Q
What studies the body using radio pharmaceuticals to evaluate?
A
PET scan
14
Q
What is it called when sound is used to visualize internal?
A
sonography
14
Q
What’s a portable fluoroscope called?
A
C-arm
15
Q
Internal preparation would include?
A
contrast media or cleansing enema
16
Q
Iodine contrast can result in:
A
hives, anaphylactic shock
17
Q
You wouldn’t want to use barium if pt has a _____ ___________
Instead you would want to use a water soluble contrast like ___
A
bowel perforation, ISO
18
Q
air used with contrast is called ______________
A
double-contrast
19
Q
What is gradually replacing the barium enema?
A
CT and virtual colonoscopy
20
Q
An x-ray study used to evaluated the patency of the oviduct?
A
hysterosalpingogram
21
Q
Malfunctioning salivary glands may be examined during?
A
sialogram
22
Q
What is it called if you have contrast studies of joints?
A
arthrogram
23
Q
What does 90% of public exposure come from?
A
medical and dental x-rays
24
What does air kerma measure
ionizing radiation in the air
25
absorbed does by patient is measured in:
Gray (Gy)
26
What does the photoelectric effect have to do with?
inner electron shells transferring energy (all of the energy)
27
What does the compton effect have to do with?
outer electron shells (part of the energy)
28
Pair production has to do with:
radiation therapy
29
The law of bergonie and tribondeau implies that radiosensitivity is greatest in?
cells that are rapidly dividing
30
At which stage of life are you most sensitive to radiation?
fetus
31
Minimal total filtration must be _____ aluminum or equivalent
2.5mm
32
A unit used to measure a quantity called exposure.
This can only be used to describe an amount of gamma rays and x-rays, and only in air
roentgen (R)
33
A unit used to measure a quantity called absorbed dose.
This relates to the amount of energy actually absorbed in some material
radiation absorbed dose (rad)
34
A unit used to derive a quantity called equivalent dose.
This relates the absorbed dose in human tissue to the effective biological damage of the radiation
roentgen equivalent man (rem)
35
Effective Dose. Dose equivalent.
Biologic effect
sievert (Sv)
36
The _____ is a unit used to measure a
unit of radioactivity
curie (Ci)
37
equation for the inverse square law
I1 D2 ²
--- = ---
I2 D1
38
Primary items needed for production of x-rays:
Source of electrons
Means to accelerate electrons (Kinetic Energy)
Way to bring electrons to a sudden stop
* Kinetic Energy → X-Ray Energy
39
______ _____ is formed when x-rays pass through
the patient's body and hit the image receptor
Latent image
40
Types of digital imaging:
computed radiography (CR)
direct digital radiography (DR)
41
Latent image is held on a phosphor plate.
Phosphor plate is encased in a cassette.
X-rays strike the plate and are trapped in high-energy state.
Computer processes the image by utilizing a laser beam
scanner.
Digitized
Creates visible image
computed radiography
42
Elements used are: cesium iodide, gadolinium
oxysulfide, and selenium.
Can be produced by direct and indirect
methods
digital radiography
43
X-rays interact directly with the element selenium creating an electric charge
direct digital radiography
44
X-rays first converted to light, then converted to an electrical signal
indirect digital radiography
45
subject density and thickness factors affecting the image
air, water, contrast, metal, pathologies
46
x-ray exposure factors
mAs, kVp, distance
47
Determines the wavelength of radiation, energy of the x-rays (penetration)
kilovoltage (kVp)
48
Exposure rate is directly proportional
Determines amount of x-rays per unit of time
milliamperage (mA)
49
As this distance decreases, detail decreases.
This distance should be kept at a maximal practical
level to keep images sharp and detailed
focal-object distance
50
As SID increases, level of detail ________
increases
51
Cross-sectional views
Eliminates need for exploratory surgery
Computer reconstructs information into an image
Computed Tomography (CT)
52
Also cross-sectional views
Utilizes manipulation of magnetic field and radio waves (no
radiation)
Magnetic Resonance Imaging (MRI)
53
Radiopharmaceutical agent injection
Physiologic condition or function
Cross-sectional images
Positron Emission Tomography (PET)
54
Radioactive materials introduced
into the body
Images of major organs
Nuclear Medicine (NM)
55
Brings digital imaging together with hospital and radiology information systems.
Total management of patient's case
Digital network can be accessed in a variety of authorized stations
Picture Archiving and Communication System (PACS)
56
has high-atomic number, shows up white on radiographic procedures
Commonly introduced intravenously to visualize blood vessels and organs
Adverse Reactions
Non-ionic contrast reduces occurrence of reactions
iodine-based contrast media
57
Similar contrast qualities as iodine.
Cannot be absorbed by the body
Great for gastrointestinal studies
Allergic reactions are rare
barium-based contrast media
58
Chest Radiography
Used with barium or iodine studies to produce a "double-contrast"
air contrast media
59
Early measurement used
to measure the amount of radiation to turn the skin red
Erythema dose
60
Ionizing radiation that
produces ions in 1 cubic centimeter of air
Air Kerma
61
Becquerel:
Activity
62
dose limit for radiation workers
50 mSv per year (annual effective dose - whole body)
63
dose limit for general public (frequent exposure)
1 mSv rems per year
64
dose limit for general public (infrequent exposure)
5 mSv rems per year
65
dose limit for embryo or fetus
0.5 mSv per month during gestation
66
dose limit for embryo or fetus
5 mSv total for gestation
67
Three main types of photon interactions that are important in radiology:
Photoelectric Effect
Compton Scatter
Pair Production
68
Most common
Knocks out inner-shell electron and transfers all energy.
Usually occurs with low- energy photons.
Photoelectric Effect interaction
69
▸ Incoming photon interacts with orbital
electron.
▸ Portion of energy is transferred.
▸ Classic (or unmodified) Scattering
▸ Entering photon changes direction
but does not transfer energy.
▸ Modified Scattering
▸ Collision occurs and partial energy is
transferred by photon
Compton Scatter interaction
70
▸ Photon of extremely high energy approaches the nucleus.
▸ Both positive electron (positron) and negative electron formed.
▸ Both positron and electron ionize other atoms.
▸ Annihilation reaction
▸ Positron reacts with orbital electron and both particles disappear and create two photons that move in the opposite direction.
▸ Does not occur in diagnostic radiography (may occur in Radiation Therapy)
Pair Production interaction
71
Cells for reproduction
germ cells
72
cells that perform all other body functions
somatic cells
73
When radiation hits a cell, there are 4 possible results:
▸ Pass through without any damage
▸ Temporary damage, but cell regains normal functions.
▸ Damage cell without cell recovering.
▸ Kill the cell
74
Ionizing radiation interacts directly with the DNA molecule and breaks in the "rung" of the DNA "ladder" occur
Direct-hit theory
75
Cells are most sensitive to ionizing radiation when they are
rapidly dividing
76
Time between initial radiation and occurrence of any biological change
latent period
77
Occurs within minutes, hours, days, or weeks (short term)
Large dose is received by the entire body over a short period of time (larger than 1 Gy)
acute radiation syndrome
78
Somatic-General body cells
Cancer, cataracts, life-span shortening
long-term effects
79
Germ cells-sexual reproduction
Transmitted to future generations and therefore not evident to the individual that was exposed
genetic
80
Measurement of radiation
dose to an individual
Dosimetry
